U.S. patent application number 11/637220 was filed with the patent office on 2007-06-28 for position input device and computer system.
Invention is credited to Yuji Katsurahira, Masaki Matsubara.
Application Number | 20070146351 11/637220 |
Document ID | / |
Family ID | 38193046 |
Filed Date | 2007-06-28 |
United States Patent
Application |
20070146351 |
Kind Code |
A1 |
Katsurahira; Yuji ; et
al. |
June 28, 2007 |
Position input device and computer system
Abstract
A position input device is provided in which signals are
transmitted from a position indicator, and signals transmitted from
the position indicator are received by a position detector device.
According to certain embodiments, an electrical double-layer
capacitor, a charging circuit which charges the electrical
double-layer capacitor, and a power transmission unit which relays
and supplies to the charging circuit power supplied from a power
supply unit external to the position indicator, are provided in the
position indicator. In other embodiments the position input device
has a built-in power supply unit, transmitting units, and a control
unit for switching the transmitting units between energized and
de-energized states. Also provided are position input systems and
computer systems including the position input device, and methods
of operating the position input device and the systems.
Inventors: |
Katsurahira; Yuji; (Saitama,
JP) ; Matsubara; Masaki; (Tokyo-to, JP) |
Correspondence
Address: |
BERENATO, WHITE & STAVISH, LLC
6550 ROCK SPRING DRIVE
SUITE 240
BETHESDA
MD
20817
US
|
Family ID: |
38193046 |
Appl. No.: |
11/637220 |
Filed: |
December 12, 2006 |
Current U.S.
Class: |
345/179 |
Current CPC
Class: |
G06F 3/04162 20190501;
G06F 3/04166 20190501; G06F 3/03545 20130101; G06F 3/04886
20130101; G06F 3/0442 20190501 |
Class at
Publication: |
345/179 |
International
Class: |
G06F 3/033 20060101
G06F003/033 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 12, 2005 |
JP |
P2005-357965 |
Mar 16, 2006 |
JP |
P2006-073102 |
Claims
1. A position input system, comprising: a position indicator for
transmitting signals; and a position detector device for receiving
signals transmitted from the position indicator, wherein said
position indicator comprises an electrical double-layer capacitor,
a charging circuit which charges the electrical double-layer
capacitor, and a power transmission unit which relays power
supplied from a power supply unit external to the position
indicator to said charging circuit.
2. The position input system according to claim 1, wherein said
power supply unit is external to said position detector.
3. The position input system according to claim 2, wherein: a coil
is in said position indicator, and said external power supply unit
is an AC magnetic field generation unit.
4. The position input system according to claim 3, wherein said
power supply unit comprises a stand housing said AC magnetic field
generation unit, wherein the stand is configured to enable setting
of said position indicator.
5. The position input system according to claim 4, wherein said
stand comprises a detector switch for selectively supplying current
to said power supply unit only when said position indicator is
received by said stand.
6. The position input system according claim 3, wherein the power
supply unit is incorporated into said position detector device for
permitting charging of the double-layer capacitor when said
position indicator is placed above said position detector
device.
7. The position input system according to claim 1, further
comprising a power supply assistance unit for receiving power from
said electrical double-layer capacitor and supplying a prescribed
voltage to said position indicator.
8. The position input system according to claim 1, wherein said
position detector device detects signals transmitted from said
position indicator based on an electrostatic coupled state with
said position indicator.
9. The position input system according to claim 1, wherein said
position detector device detects signals transmitted from said
position indicator based on electromagnetic coupling with said
position indicator.
10. The position input system according to claim 9, wherein said
position indicator comprises a resonance circuit comprising a coil
and capacitor.
11. The position input system according to claim 1, wherein said
position indicator comprises: a voltage detection unit for
detecting when the voltage across said electrical double-layer
capacitor has dropped to or below a prescribed voltage value, and
an information transmission unit for transmitting information
indicating the detection of the drop in voltage by said voltage
detection unit to said position detector device.
12. A computer system, comprising: a position input system
comprising a position indicator for transmitting signals, and a
position detector device for receiving signals transmitted from the
position indicator; a display device; and a computer for processing
positions detected by said position input device, wherein said
position indicator comprises an electrical double-layer capacitor;
a charging circuit for charging the electrical double-layer
capacitor; and a power transmission unit for relaying and
supplying, to said charging circuit, power from a power supply unit
external to the position indicator.
13. The computer system according to claim 12, further comprising:
a voltage detection unit for detecting when the voltage of said
electrical double-layer capacitor has dropped to or below a
prescribed voltage value; and an information transmission unit for
transmitting to said position detector device information
indicating detection of the voltage drop by the voltage detection
unit.
14. The computer system according to claim 13, further comprising
an AC magnetic field generation unit as said power supply unit,
wherein a coil is provided in said position indicator, and wherein
said computer is operable, upon reception by said position detector
device of the information indicating detection of the voltage drop
transmitted from said information transmission unit, to supply
current to said AC magnetic field generation unit.
15. The computer system according to claim 13, wherein the computer
is operable, based on the information indicating detection of the
voltage drop transmitted from said information transmission unit,
to cause a report to be displayed by said display device.
16. The computer system according to claim 13, further comprising
an AC magnetic field generation unit as said power supply unit,
wherein a coil is provided in said position indicator, and wherein
said computer is operable to supply current to said AC magnetic
field generation unit when a prescribed time has elapsed from the
previous supply of current to said AC magnetic field generation
unit.
17. The computer system according to claim 13, further comprising a
prompt to notify a user, based on the information indicating
detection of the voltage drop transmitted from said information
transmission unit, to charge said electrical double-layer
capacitor, wherein said prompt is located on the position
indicator.
18. The computer system according to claim 13, further comprising a
prompt to notify a user, based on the information indicating
detection of the voltage drop transmitted from said information
transmission unit, to charge said electrical double-layer
capacitor, wherein said prompt is located on the position detector
device.
19. The computer system according to claim 13, further comprising a
prompt to notify a user, based on the information indicating
detection of the voltage drop transmitted from said information
transmission unit, to charge said electrical double-layer
capacitor, wherein said prompt is located on the power transmission
unit.
20. The computer system according to claim 13, further comprising
an AC magnetic field generation unit as said power supply unit,
wherein a coil is provided in said position indicator, and wherein
said computer is operable to supply current to said AC magnetic
field generation unit when the information indicating detection of
the voltage drop transmitted by said information transmission unit
is not received by said position detector device within a
prescribed time from the previous passage of current to said AC
magnetic field generation unit.
21. The computer system according to claim 12, further comprising
an AC magnetic field generation unit as said power supply unit,
wherein a coil is provided in said position indicator, and wherein
said computer is operable to issue a charging request and supply
current to said AC magnetic field generation unit when a prescribed
time has elapsed from the previous supply of current to said AC
magnetic field generation unit.
22. The computer system according to claim 12, further comprising
an AC magnetic field generation unit as said power supply unit,
wherein a coil is provided in said position indicator, and wherein
said power supply unit comprises a detection switch which is
activated when said position indicator is placed in a charging
position with respect to said power supply unit.
23. The computer system according to claim 12, wherein said power
supply unit is integrated into said position detector device.
24. A method of charging a position indicator of a position input
system comprising the position indicator for transmitting signals
and a position detector device for receiving signals transmitted by
the position indicator, said method comprising the steps of:
providing a position indicator with an electrical double-layer
capacitor, a charging circuit which charges the electrical
double-layer capacitor, and a power transmission unit; and
supplying power from a power supply unit external to the position
indicator, and causing the power transmission unit to relay the
power to the charging circuit.
25. A method of operating a computer system, comprising the steps
of: providing a position input system comprising a position
indicator for transmitting signals, and a position detector device
for receiving signals transmitted from the position indicator;
providing a computer for processing information based on positions
detected by said position input device; and supplying power from a
power supply unit external to the position indicator, and causing
the power transmission unit to relay the power to the charging
circuit.
26. The method according to claim 25, including the further steps
of: detecting when the voltage of the electrical double-layer
capacitor has dropped to or below a prescribed voltage value; and
transmitting to the position detector device information indicating
detection of the voltage drop.
27. A position pointing device for transmitting a positioning
signal to a position detecting tablet, the position pointing device
comprising: An integrated power supply unit; a plurality of signal
transmitting units provided at a plurality of portions of a
position pointing device; and a control unit for switching said
plurality of signal transmitting units between energized and
de-energized states.
28. A position pointing device according to claim 27, wherein said
plurality of signal transmitting units comprises first and second
signal transmitting units respectively provided at opposite end
portions of said position pointing device.
29. The position pointing device according to claim 28, wherein
said first and second signal transmitting units transmit a
pen-point signal and an eraser signal, respectively.
30. A position pointing device according to claim 27, wherein said
control unit alternately switches said signal transmitting units
between an energized state and a de-energized state.
31. A position pointing device according to claim 27, further
comprising: a direction detecting unit for detecting the direction
in which said position pointing device is arranged relative to the
position detecting tablet, and wherein said control unit energizes
whichever of the signal transmission units faces towards the
position detector tablet based on a detected result of said
direction detecting unit.
32. A position pointing device according to claim 31, wherein said
direction detecting unit comprises a stylus pressure detecting
unit, and wherein said control unit is operable to energize
whichever of the signal transmission units touches the position
detector tablet based on detection by the stylus pressure detecting
unit of a load greater than a predetermined load.
33. A position pointing device according to claim 32, wherein said
control unit is operable to sequentially operate said plurality of
signal transmitting units if it is determined by the stylus
pressure detecting unit that a load greater than said predetermined
load is not detected from any one of said plurality of signal
transmitting units.
34. A position pointing device according to claim 31, wherein said
direction detecting unit is a touch-sensitive sensor and said
control unit is operable to energize whichever of said signal
transmission units is associated with an end of the position
pointing device which touches the position detecting tablet.
35. A position pointing device for transmitting a positioning
signal to a position detecting tablet, the position pointing device
comprising: a built-in power supply unit; a plurality of signal
transmitting units provided at a plurality of portions of said
position pointing device; and a power control unit for switching
magnitude of transmission power of said signal transmitting units
between at least two power levels.
36. A position pointing device according to claim 35, wherein first
and second signal transmitting units of said plurality of signal
transmitting units are disposed at opposite end portions of said
position pointing device to transmit a pen-point signal and an
eraser signal, respectively.
37. A position pointing device according to claim 35, further
comprising a direction detecting unit for detecting the direction
of said position pointing device relative to a position detecting
tablet, wherein said power control unit is operable to increase,
based on a detected result of the direction detecting unit, a
magnitude of transmission power from whichever of said signal
transmitting units is located on a side of said positioning
pointing device nearer to the position detecting tablet, so that
the magnitude of transmission power from said signal transmitting
unit located on the side nearer to the position detecting tablet is
greater than a magnitude of transmission power from whichever of
said signal transmitting units is on the opposite side of said
positioning pointing device.
38. A position pointing device according to claim 35, wherein said
control unit alternately switches said signal transmitting units
between the energized state and the de-energized state.
39. A position input system, comprising: a position pointing device
for transmitting positioning information signals, said position
pointing device comprising a built-in power supply unit, a
plurality of signal transmitting units provided at a plurality of
portions of said position pointing device, and a power control unit
for controlling transmission power of each of said plurality of
signal transmitting units; a position detecting tablet for
receiving the positioning information signals from the position
pointing device; and a discriminating unit for discriminating the
positioning information signals from said plurality of signal
transmitting units.
40. A position input system according to claim 39, wherein said
discriminating unit comprises a first discriminating unit provided
at a first end portion of said position pointing device to
discriminate a pen-point signal, and wherein said position input
system further comprises a second discriminating unit provided at a
second end portion of said position pointing device to discriminate
an eraser signal.
41. A position input system according to claim 39, wherein said
control unit alternately switches said signal transmitting units
between the energized state and the de-energized state.
42. A computer system, comprising: a position pointing device for
transmitting positioning signals, the position pointing device
comprising a built-in power supply unit, a plurality of signal
transmitting units provided at a plurality of portions of said
position pointing device, and a power control unit for controlling
transmission power of each of said plurality of signal transmitting
units; a position detecting tablet for receiving the positioning
signals from the position pointing device; a discriminating unit
for discriminating the positioning signals from said plurality of
signal transmitting units; and a computer for processing the
positioning signals from said position pointing device and
discrimination information from said discriminating unit.
43. A computer system according to claim 42, wherein said
discriminating unit comprises a first discriminating unit provided
at a first end portion of said position pointing device to
discriminate a pen-point signal, and wherein said computer system
further comprises a second discriminating unit provided at a second
end portion of said position pointing device to discriminate an
eraser signal.
44. A computer system according to claim 42, wherein said control
unit alternately switches said signal transmitting units between
the energized state and the de-energized state.
45. A method for charging a position pointing device, comprising
the steps of: providing a position pointing device for transmitting
a positioning signal to a position detecting tablet, the position
pointing device comprising a built-in power supply unit, a
plurality of signal transmitting units provided at a plurality of
portions of said position pointing device, and a control unit; and
switching said plurality of signal transmitting units between
energized or de-energized states.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS AND CLAIM TO PRIORITY
[0001] The present application claims the benefit of Japanese
Application No. P2005-357965, filed on Dec. 12, 2005, which
application is incorporated herein by reference and to which
priority is claimed.
[0002] The present application also claims the benefit of Japanese
Application No. P2006-073102 filed on Mar. 16, 2006, which
application is incorporated hereby by reference and to which
priority is claimed.
FIELD OF THE INVENTION
[0003] Aspects of this invention relate to a battery-free position
pointing device (also referred to herein as a position indicator),
a position input system, and a computer system which detect
position by transmitting and receiving signals between the position
indicator and the position detection device, and to related
methods.
[0004] Additional aspects of the present invention relate to a
position pointing device with a built-in power source, a position
input system, and a computer system suitable for use in detecting
position, preferably by electromagnetic induction, and preferably
in a manner in which the service life of the built-in power supply
of the position pointing device is prolonged.
BACKGROUND OF THE INVENTION
[0005] Position input systems, also known as pen tablets or
tablet/digitizers, have seen widespread use as input devices for
computers, for example. The position input system generally
comprises a pen-type or stylus-type position indicator (also
referred to herein as a position pointing device) for indicating a
position on a tablet, and a position detection device. In such a
position input system signals transmitted from the position
indicator are received by the position detection device to detect
the position on the tablet indicated by the position indicator. So
far various technologies have been developed for detecting the
position designated on the tablet. Of these various kinds of
developed technologies, an electromagnetic induction system
position detecting apparatus like the invention described in
Japanese Published Patent Application No. 2-53805 is known for
detecting the position designated on the tablet.
[0006] In recent years, position input systems have appeared which
are integrated with a liquid crystal display device, and which
enable operation of the position indicator on a display screen.
Generally in such a position input system, electric waves are
transmitted to the position indicator from the position detector
device integrated with the display screen, and these electric waves
are utilized to transmit signals from the position indicator. In
such a position input system, because the signals transmitted from
the position indicator to the position detection device are
comparatively weak, the sensitivity and precision of the position
detector device may be reduced in an environment of intense
electromagnetic noise, such as may be generated by the liquid
crystal display device or other sources. As a countermeasure, the
signals transmitted from the position detector device may be
strengthened. However, strengthening of the signals is problematic
inasmuch as power consumption by the position detector device is
increased.
[0007] It has been proposed to incorporate a battery into the
position indicator, so that the transmission of signals from the
position detector device becomes unnecessary. Using such a method,
strong signals can be transmitted from the position indicator with
low power consumption.
[0008] However, the use of batteries can also raise problems. In
the case of the above-described position indicator, replacing the
battery is time consuming and troublesome. Also, if the intensity
of signals transmitted from the position indicator is to be
increased, power consumption is increased and battery depletion
occurs in a short length of time, so that the batteries built into
the position indicator may need to be replaced frequently, causing
further inconvenience. In addition, the weight of a position
indicator incorporating a battery is increased significantly, and
there is the further problem that operating properties are severely
degraded.
[0009] Recently, it has been known to provide position pointing
devices with tuning circuits at both ends of their pen-like bodies.
The tuning circuit at the first end is able to transmit written
information, and the tuning circuit at the other or second end is
able to transmit other information, such as the erasing of
information. See Japanese Published Patent Application No. 8-96350.
It has been proposed to provide such position pointing devices with
built-in power supply units and oscillation units to increase the
magnitude of transmission output, and thereby improve accuracy in
detecting position. See Japanese Published Patent Application No.
10-214148.
[0010] However, if a position pointing device possesses a built-in
power supply unit (i.e., a battery) and a plurality of oscillation
units instead of the above-discussed tuning circuits, then power
consumption of the built-in power supply unit is increased by a
multiple equal to the number of oscillation units in the position
pointing device, e.g., if the position pointing device contains two
oscillation units, then power consumption is doubled. Accordingly,
the time period during which the position pointing device may be
operated prior to consumption of all of the power in the built-in
power supply is lessened correspondingly. As a result, the battery
must be replaced or recharged more frequently, inconveniencing the
operator.
SUMMARY OF THE INVENTION
[0011] Aspects of this invention were devised in light of the above
circumstances, and certain aspects have as an object the provision
of a position indicator device capable of stable position detection
without readily being affected by external noise even under low
power consumption, which is lightweight, and which does not require
battery replacement. It is another object of the invention to
provide a position input system and a computer system to which this
position indicator device is applied.
[0012] A first aspect of the invention provides a position input
system comprising a position indicator for transmitting signals and
a position detector device for receiving the signals transmitted
from the position indicator. The position indicator comprises an
electrical double-layer capacitor, a charging circuit to charge the
electrical double-layer capacitor, and a power transmission unit to
relay and supply the charging circuit with power supplied from a
power supply unit external to the position indicator.
[0013] According to a preferred implementation of this first aspect
of the invention, signals can be transmitted using an electrical
double-layer capacitor provided in the position indicator, so that
there is greater freedom with respect to power consumption for
signal transmission. For example, compared with a case in which
signals are transmitted to the position indicator from the position
detector device, according to this implementation of the first
aspect of the invention signals transmitted from the position
indicator can be more reliably detected by the position detector
device even at extremely low power consumption, thus permitting
power consumption by the position detector device to be greatly
reduced. As a result, signals are transmitted reliably from the
position indicator to the position detector device with low power
consumption and without easily being affected by external noise.
Further, strong signals can be reliably received within the
position detector device, so that the position indicated by the
position indicator can be detected.
[0014] Further, by using an electrical double-layer capacitor,
short-duration charging is possible, and a position indicator with
the advantages of light weight and compactness can be realized.
That is, the position indicator of the position input system of
this aspect of the invention differs from a position indicator
incorporating a primary battery in that troublesome and
time-consuming battery replacement is not required. Further,
because charging is possible in an extremely short time, there is
little inconvenience arising from an inability to use the position
indicator until charging is complete. The light weight of the
position indicator also affords excellent operating properties.
[0015] According to another implementation of this first aspect of
the invention, the position input system further comprises an
external power supply unit. The inclusion of the external power
supply unit provides various benefits, such as the simplification
of charging of the electrical double-layer capacitor, and
enhancement of the usability of the system.
[0016] According to another implementation of this first aspect of
the invention, a coil is provided in the position indicator, and an
AC magnetic field generation unit is provided as the power supply
unit. In this case, by using the AC magnetic field generation unit
to generate a magnetic field, an induced current flows in the coil,
causing the electrical double-layer capacitor to be charged. Power
can be supplied through this magnetic field without requiring
contact, so that freedom of design of the position indicator is
enhanced, and the durability of the position indicator and the
power supply unit can be improved.
[0017] According to still another implementation of this first
aspect of the invention, as the power supply unit, the AC magnetic
field generation unit is provided in a stand in which the position
indicator can be set. By setting the position indicator in the
stand, the electrical double-layer capacitor can be charged, so
that operation related to charging becomes extremely simple, and
operability is improved.
[0018] According to yet another implementation of this first aspect
of the invention, a power supply assistance unit for receiving
power from the electrical double-layer capacitor and supplying a
prescribed voltage to the position indicator is provided in the
position indicator. The voltage across the terminals of the
electrical double-layer capacitor is high immediately after
charging, and is expected to decline as power is consumed. The
power supply assistance unit preferably is operable to supply a
prescribed voltage based on the power of the electrical
double-layer capacitor, so that when various circuitry is
incorporated into the position indicator, stable operation of the
circuitry is assured.
[0019] According to a further implementation of this first aspect
of the invention, the position detector device detects signals
transmitted from the position indicator based on a static coupled
state with the position indicator. Moreover, the position detector
device may be a device which detects signals transmitted from the
position indicator based on electromagnetic coupling with the
position indicator. Further, the position indicator may employ a
configuration comprising a resonance circuit comprising a coil and
a capacitor.
[0020] According to still a further implementation of the first
aspect of the invention, the position indicator comprises a voltage
detection unit and an information transmission unit. The voltage
detection unit detects when the voltage of the electrical
double-layer capacitor has fallen to or below a prescribed voltage
value. The information transmission unit transmits information
indicating detection by the voltage detection unit of the fallen
voltage to the position detector device. The transmission of this
information allows the position detector device to automatically
detect and notify the user of the need for charging.
[0021] It should be understood that the above implementations of
the first aspect may be practiced in various combinations.
[0022] According to a second aspect of the invention, a computer
system is provided. The computer system comprises a position input
system, a display device for displaying screens, and a computer for
processing information based on positions detected by the position
input system. The position input device comprises a position
indicator which transmits signals, and a position detector device
which receives signals transmitted from the position indicator. The
position indicator contains an electrical double-layer capacitor, a
charging circuit for charging the electrical double-layer
capacitor, and a power transmission unit for relaying and supplying
the charging circuit with power supplied from a power supply unit
external to the position indicator.
[0023] According to the second aspect of the invention, preferably
signals can be transmitted using the electrical double-layer
capacitor provided in the position indicator. As a consequence,
power consumption for signal transmission is greatly reduced, and
the position indicator may be operated without significant
impediment from external noise. In this system, the time and
trouble otherwise that would be involved in the replacement of a
battery in the position indicator may be avoided. Moreover by using
the electrical double-layer capacitor, the position indicator can
be charged in an extremely short time. Further, the position
indicator can be made lightweight, for excellent operability.
[0024] According to an implementation of the second aspect of the
invention, the position indicator may further include a voltage
detection unit which detects when the voltage of the electrical
double-layer capacitor has fallen to or below a prescribed voltage
value, and an information transmission unit which transmits to the
position detector device information indicating detection by the
voltage detection unit of the fallen voltage.
[0025] According to this implementation of the second aspect of
this invention, the need to charge the position indicator may be
detected in the position detector device when the voltage of the
electrical double-layer capacitor in the position indicator has
fallen below the prescribed voltage value, and the position
indicator can be recharged.
[0026] According to another implementation of this second aspect of
the invention, the computer system further comprises an AC magnetic
field generation unit as the power supply unit, and a coil is
provided in the position indicator. The computer is operable to use
the position detector device to receive information transmitted by
the information transmission unit provided in the position
indicator. When, based on the information from the information
transmission unit, it is determined that the electrical
double-layer capacitor must or should be charged, current is
supplied to the AC magnetic field generation unit.
[0027] In this implementation, current is supplied to the AC
magnetic field generation unit which charges the electrical
double-layer capacitor of the position indicator only when the
information transmission unit reports the drop in the voltage of
the electrical double-layer capacitor. Power consumption can be
thereby rendered efficient by avoiding the unnecessary supply of
current to the AC magnetic field generation unit, i.e., when the
voltage of the electrical double-layer capacitor has not fallen. In
addition, charging can be performed rapidly when necessary.
[0028] According to another implementation of this second aspect of
the invention, the computer is operable to determine, based on
information transmitted from the position indicator and received by
the position detector device, whether the electrical double-layer
capacitor must or should be charged, and to cause a report to be
generated and displayed by the display device. The report may
notify the user that the position indicator requires charging, so
the user views the report and performs charging. Thus, the user can
concentrate on operation of the device without paying special
consideration to the timing of charging, for greater convenience to
the user.
[0029] According to still another implementation of this second
aspect of the invention, the computer system further comprises an
AC magnetic field generation unit employed as the power supply
unit, with a coil provided in the position indicator. The computer
is operable to supply current to the AC magnetic field generation
unit when a prescribed time has elapsed from the previous supply of
current to the AC magnetic field generation unit. According to a
preferred practice of this implementation, after the AC magnetic
field generation unit is supplied with current, an estimated timing
value is determined to anticipate a drop in the voltage of the
electrical double-layer capacitor. Current is again supplied to the
AC magnetic field generation unit upon expiration of the estimated
timing value. In this manner, power consumption can be rendered
efficient, without unnecessarily supplying unneeded current to the
AC magnetic field generation unit. In addition, charging can be
performed rapidly when necessary. Further, current can be supplied
to the AC magnetic field generation unit with appropriate timing
without performing complex processing, thereby enabling transition
to the charged state.
[0030] According to yet another implementation, a configuration may
be employed in which the computer system further comprises an AC
magnetic field generation unit as the power supply unit, with a
coil provided in the position indicator. According to this
implementation, current is supplied to the AC magnetic field
generation unit within a timing which anticipates a drop in the
voltage of the electrical double-layer capacitor, without waiting
for transmission of information from the position indicator. More
specifically, the computer causes current to be supplied to the AC
magnetic field generation unit during the interval before or when a
prescribed time has elapsed from the previous supply of current to
the AC magnetic field generation unit, even if the position
detector device has not yet received information indicating
detection of the voltage drop transmitted from the information
transmission unit provided in the position indicator. Accordingly,
charging can be performed rapidly when necessary, for example, even
when for example the voltage across the electrical double-layer
capacitor drops sharply and the above information cannot be
transmitted to the position detector device.
[0031] According to additional implementations of this second
aspect of the invention, the computer system comprises a prompt for
notifying the operator to charge the electrical double-layer
capacitor. The prompt may be located on the position indicator,
position detector device, and/or the power transmission unit.
[0032] According to yet an additional implementation of the second
aspect, the power supply unit is integrated on or into the position
detector device to form a unitary piece.
[0033] It should be understood that the above implementations of
the second aspect may be practiced in various combinations.
[0034] According to a third aspect of the invention, a method is
provided for charging a position indicator of a position input
system, which comprises a position indicator for transmitting
signals and a position detector device for receiving signals
transmitted by the position indicator. The position indicator
includes an electrical double-layer capacitor, a charging circuit
which charges the electrical double-layer capacitor, and a power
transmission unit. Power is supplied from a power supply unit
external to the position indicator, and the power transmission unit
relays the power to the charging circuit.
[0035] A fourth aspect of the invention provides a method of
operating a computer system. A position input system comprises a
position indicator for transmitting signals, a position detector
device for receiving signals transmitted from the position
indicator is provided, and a computer for processing information
based on positions detected by said position input system. Power is
supplied from a power supply unit external to the position
indicator, and the power transmission unit relays the power to the
charging circuit.
[0036] According to an implementation of this fourth aspect of the
invention, the method further comprises detecting when the voltage
of the electrical double-layer capacitor has dropped to or below a
prescribed voltage value, and transmitting to the position detector
device information indicating detection of the voltage drop.
[0037] Advantageously, in preferred aspects and implementations of
this invention described above, an electrical double-layer
capacitor serves as a power storage of the position indicator, so
that there is no need to supply power to the position indicator
from the position detector device. Strong signals can be received
from the position indicator by the position detector device with
low power consumption and without easily being affected by external
noise. Further, no time or trouble need be taken to replace
batteries in the position indicator, and charging can be performed
in an extremely short time. Moreover, the electrical double-layer
capacitor is lighter than ordinary batteries while affording high
capacity, so that the position indicator enjoys the advantages of
light weight and excellent operability. As a result, a position
input system comprising a position indicator with light weight and
excellent operability, as well as a computer system comprising the
position input system, can be realized.
[0038] Another object of the present invention is to provide a
position pointing device having a built-in battery, a position
input system comprising a position pointing device having a
built-in battery and a position detecting apparatus, and a computer
system possessing one or more of the following advantages: an
efficient power consumption, even when a plurality of oscillation
units is provided; and a lower frequency of operational disruptions
(e.g., battery changes and recharges) than is encountered relative
to conventional devices containing a built-in battery.
[0039] A fifth aspect of the invention is directed to a position
pointing device for transmitting a positioning signal to a position
detecting tablet. The position pointing device includes a built-in
power supply unit, signal transmitting units provided at a
plurality of portions of the position pointing device, and a
control unit for switching the signal transmitting units between
energized or de-energized states.
[0040] According to an exemplary implementation of this fifth
aspect of the invention, the plurality of signal transmitting units
includes first and second signal transmitting units respectively
provided at opposite end portions of the position pointing device,
preferably to transmit a pen-point signal and an eraser signal,
respectively.
[0041] In another implementation of the position pointing device of
the fifth aspect of the invention, the control unit alternately
switches the signal transmitting units between the energized and
de-energized states.
[0042] According to still another implementation of the fifth
aspect of the invention, the position pointing device further
includes a direction detecting unit for detecting the direction in
which the position pointing device is arranged relative to the
position detecting tablet. The control unit is operable to energize
whichever of the signal transmission units faces the position
detecting tablet based on a detected result of the direction
detecting unit.
[0043] According to still another implementation of the position
pointing device of the fifth aspect of the invention, the direction
detecting unit is a stylus pressure detecting unit and the control
unit is operable to energize whichever of the signal transmission
units is determined to be in use based on detection by the stylus
pressure detecting unit of a load greater than a predetermined
load. At the same time, preferably the control unit de-energizes
the signal transmission unit determined not to be in use.
[0044] In further implementation of the fifth aspect of the
invention, the control unit is operable to sequentially operate the
plurality of signal transmitting units if it is determined by the
stylus pressure detecting unit that a load greater than the
predetermined load is not detected from any one of the signal
transmitting units.
[0045] In still a further implementation of the fifth aspect of the
invention, the direction detecting unit is a touch-sensitive sensor
and the control unit is operable to energize whichever of the
signal transmission units is associated with an end of the position
pointing device which touches the position detecting tablet.
Preferably, the control unit de-energizes whichever of the signal
transmission units is associated with an end of the position
pointing device which does not touch the position detecting
tablet.
[0046] It should be understood that the above implementations of
the fifth aspect of the invention may be practiced in various
combinations.
[0047] A sixth aspect of the invention is directed to a position
pointing device for transmitting a positioning signal to a position
detecting tablet. This position pointing device includes a built-in
power supply unit, a plurality of signal transmitting units
provided at a plurality of portions of the position pointing
device, and a power control unit for switching magnitude of
transmission power of said signal transmitting units between at
least two levels.
[0048] In accordance with an implementation of the sixth aspect of
the invention, first and second signal transmitting units of the
plurality of signal transmitting units are respectively provided at
opposite end portions of the position pointing device to transmit a
pen-point signal and an eraser signal, respectively.
[0049] In the position pointing device according to another
implementation of the sixth aspect of the invention, the position
pointing device further includes a direction detecting unit for
detecting the direction of the position pointing device relative to
the position detecting tablet. The power control unit is operable
to increase, based on a detected result of the direction detecting
unit, a magnitude of transmission power from whichever of the
signal transmitting units is located on a side of the position
pointing device nearer to the position detecting tablet, so that
the magnitude of transmission power from the signal transmitting
unit located on the side nearer to the position detecting tablet is
greater than the magnitude of transmission power from whichever of
the signal transmitting units is on the opposite side of the
position pointing device.
[0050] A seventh aspect of the invention is directed to a position
input system including a position pointing device for transmitting
positioning information signals. The position pointing device
includes a built-in power supply unit, a plurality of signal
transmitting units provided at a plurality of portions of the
position pointing device, and a power control unit for controlling
the transmission power of each of a plurality of signal
transmitting units. The position input system further includes a
position detecting tablet for receiving the positioning signals
from the position pointing device. A discriminating unit
discriminates the signals from the signal transmitting units.
[0051] In an exemplary implementation of the position input system
of the seventh aspect of the invention, the discriminating unit is
a first discriminating unit provided at a first end portion of the
position pointing device to discriminate a pen-point signal, and
the position input system further includes a second discriminating
unit provided at a second end portion of the position pointing
device for discriminating an eraser signal.
[0052] The eighth aspect of the present invention is directed to a
computer system including a position pointing device for
transmitting positioning signals. The position pointing device
includes a built-in power supply unit, a plurality of signal
transmitting units provided at a plurality of portions of the
position pointing device, and a power control unit for controlling
transmission power of each of a plurality of signal transmitting
units. The computer system further includes a position detecting
tablet for receiving positioning signals from the position pointing
device. A discriminating unit discriminates the signals from a
plurality of signal transmitting units. A computer is provided for
processing the positioning information from the position pointing
device and discrimination information from the discriminating
unit.
[0053] In an exemplary implementation of the system of the eighth
aspect of the invention, the discriminating unit is a first
discriminating unit provided at a first end portion of the position
pointing device to discriminate a pen-point signal, and the system
further includes a second discriminating unit provided at a second
end portion of the position pointing device for discriminating an
eraser signal.
[0054] A ninth aspect of the invention provides a method for
charging a position pointing device used for transmitting a
positioning signal to a position detecting tablet. The position
pointing device comprises a built-in power supply unit, a plurality
of signal transmitting units provided at a plurality of portions of
the position pointing device, and a control unit. The control unit
switches the plurality of signal transmitting units between
energized or de-energized states.
[0055] According to the position pointing device, the position
detecting apparatus, the computer system, and method encompassed in
the fifth to ninth aspects of the present invention, the position
pointing device has a built-in power supply unit so that accuracy
in detecting position can be improved. Even when the position
pointing device includes a plurality of oscillation circuits, power
consumption by the position pointing device can be reduced. Also,
the battery change and recharge frequency can be reduced, and the
position detecting apparatus can be used without significant
interruption.
BRIEF DESCRIPTION OF THE DRAWINGS
[0056] The accompanying drawings are incorporated in and constitute
a part of the specification. The drawings, together with the
general description given above and the detailed description of the
preferred embodiments and methods given below, serve to explain the
principles of the invention. In such drawings:
[0057] FIG. 1 is a simplified diagram of a system of a first
embodiment of the invention;
[0058] FIG. 2 is an oblique view of a position indicator;
[0059] FIG. 3 is an electrical diagram of an internal circuit
incorporated in a position indicator;
[0060] FIG. 4 is an electrical diagram of an internal circuit
incorporated in a tablet;
[0061] FIG. 5 is a timing chart illustrating transmission operation
by a position indicator, in which (A) illustrates the output from
terminal P0 of a controller, (B) illustrates the voltage across the
terminals of a resonance circuit, (C) shows the operating state,
and (D) shows data;
[0062] FIG. 6A is an oblique, cross-sectional view of a charger,
and FIG. 6B is a functional block diagram for the charger;
[0063] FIG. 7 is a functional block diagram showing the
configuration of the control system of a computer main unit;
[0064] FIG. 8 is a flowchart showing charging control processing
executed in the computer main unit;
[0065] FIG. 9 illustrates an example of a charge request message
displayed on a monitor during charging control processing;
[0066] FIG. 10A shows an example of a light-emitting portion on a
position indicator;
[0067] FIG. 10B shows an example of a light-emitting portion on a
tablet;
[0068] FIG. 10C is a cross-sectional view of a light-emitting
portion on a charger;
[0069] FIG. 11 is a flowchart illustrating charging control
processing in a modified example of the first embodiment;
[0070] FIG. 12 is a flowchart illustrating charging control
processing in another modified example of the first embodiment;
[0071] FIG. 13A is an oblique, cross-sectional view of a charger of
a second embodiment of the invention, and FIG. 13B is a functional
block diagram for the charger;
[0072] FIG. 14 is an oblique view illustrating the tablet of a
third embodiment of the invention;
[0073] FIG. 15 is an oblique view of a tablet of a fourth
embodiment of the invention;
[0074] FIG. 16 illustrates a tablet-type computer of a fifth
embodiment of the invention;
[0075] FIG. 17 is a diagram of the internal circuitry of a position
indicator of a sixth embodiment of the invention;
[0076] FIG. 18 is a diagram of the internal circuitry of a tablet
of the sixth embodiment of the invention;
[0077] FIG. 19 is an electrical block diagram illustrating a
position pointing device according to a seventh embodiment of the
present invention;
[0078] FIG. 20 is an electrical block diagram showing illustrating
a position pointing device according to an eighth embodiment of the
present invention;
[0079] FIG. 21 is a perspective, fragmentary cross-sectional view
of a position pointing stylus pen serving as the above-mentioned
position pointing device of the eighth embodiment of the present
invention;
[0080] FIGS. 22A, 22B, and 22c are diagrams of waveforms of signals
to which reference will be made in explaining operations of the
position pointing device according to the eighth embodiment of the
present invention;
[0081] FIG. 23 is an electrical block diagram illustrating a
position pointing device according to a ninth embodiment of the
present invention;
[0082] FIGS. 24A and 24B are waveform diagrams of signals to which
reference will be made in explaining operations of the position
pointing device according to the ninth embodiment of the present
invention;
[0083] FIG. 25 is a perspective view of a position pointing stylus
pen serving as the above-mentioned position pointing device
according to the ninth embodiment of the present invention;
[0084] FIG. 26 is an electrical block diagram illustrating a
position pointing device according to a tenth embodiment of the
present invention; and
[0085] FIG. 27 is an electrical block diagram illustrating a
position detecting apparatus and a computer according to an
eleventh embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) AND PREFERRED
METHOD(S)
[0086] Reference will now be made to the presently preferred
embodiments and methods of the invention as illustrated in the
accompanying drawings, in which like reference characters designate
like or corresponding parts throughout the drawings. It should be
noted, however, that the invention in its broader aspects is not
limited to the specific details, representative devices and
methods, and illustrative examples shown and described in this
section in connection with the preferred embodiments and methods.
The invention according to its various aspects is particularly
pointed out and distinctly claimed in the attached claims read in
view of this specification, and appropriate equivalents.
First Embodiment
[0087] FIG. 1 shows an overview of a computer system 10 of a first
embodiment of the invention.
[0088] In computer system 10 shown in FIG. 1, a monitor 12 and a
keyboard 13 are connected to a computer main unit 11. An LCD
(Liquid Crystal Display) or other display screen is integrated with
a tablet 20 into the monitor 12 to perform position input using a
position indicator 30, such as a pen. In addition, a charger 50, as
best shown in FIG. 6A as a stand or holder, to charge the position
indicator 30, described below, is connected to the computer main
unit 11.
[0089] The tablet 20 (position detector device) functions as part
of a position input system through use in conjunction with the
position indicator 30, and detects a position indicated by the
position indicator 30 on an input area 20A of the screen of the
monitor 12, and outputs information, e.g., the position coordinates
to the computer main unit 11.
[0090] The charger 50 is used to charge the position indicator 30,
and is supplied with power by the computer main unit 11.
[0091] FIG. 2 shows an external view of the position indicator 30.
A core 32 protrudes from the tip of a case 31. Two switches 33, 34
are positioned on a side face of the case 31, and an internal
circuit 40, as best shown in FIG. 3, to transmit signals to the
tablet 20 is housed within the case 31.
[0092] The switches 33, 34 illustrated in FIG. 2 are represented by
the same reference numerals, i.e., 33 and 34, respectively, in the
diagram of the internal circuit 40, as illustrated in FIG. 3. The
core 32 shown in FIG. 2 is linked to a variable-capacitance
capacitor 425 in the internal circuit 40, as best shown in FIG. 3.
While the position indicator 30 is used in operations in the
display area (input area 20A) of the monitor 12, when pressure is
applied to the core 32, the pressure on the core 32 is transmitted
to the variable-capacitance capacitor 425, and the capacitance of
the variable-capacitance capacitor 425 changes according to the
magnitude of the pressure. The switches 33, 34 are operated by the
user as desired.
[0093] FIG. 3 shows the configuration of the internal circuit 40 of
the position indicator 30. The internal circuit 40 comprises a
controller (microprocessor) 401, and operates according to a
prescribed program. In FIG. 3, an oscillator 421 generates a clock
signal to cause operation of the controller 401.
[0094] A resonance circuit 410 resonates at a prescribed frequency,
and is connected via a capacitor 406 to the terminal P0 of the
controller 401. A signal with the same frequency as the resonance
frequency of the resonance circuit 410 is output from the terminal
P0 of the controller 401 with timing as best shown in FIG. 5, to
cause radiation of an AC magnetic field from the resonance circuit
410. An electrical double-layer capacitor 403 supplies power to the
controller 401 via a switch 404. A capacitor 405 stabilizes the
voltage supplied to the controller 401. An aluminum electrolytic
capacitor of a value of, for example, several tens to several
hundreds of microfarads is appropriate for capacitor 405.
[0095] A voltage detector 407 detects whether the voltage across
the capacitor 405 is equal to or greater than a prescribed value,
which in this embodiment is 1.8 V, although other values may be
used. If the voltage is 1.8 V or higher, a high level voltage
(e.g., a voltage substantially equal to the voltage across the
capacitor 405) is output. If the voltage is less than 1.8 V, a low
level voltage (e.g., 0 V) is output. The switch 404 is switched to
the "on" state or the "off" state by a control signal output from
terminal P2 of the controller 401. As with an ordinary capacitor,
the voltage held by the electrical double-layer capacitor 403
declines with discharge. In order to hold constant the level of the
AC magnetic field transmitted from the resonance circuit 410, the
level of the signal output from terminal P0 of the controller 401
is held constant, and, to this end, the power supply voltage of the
controller 401, that is, the voltage across the capacitor 405, is
held constant. To achieve this, in the present embodiment, a power
supply assistance unit, described below, is used.
[0096] The controller 401 repeats the operation to transmit signals
from terminal P0 with the timing shown in FIG. 5. By detecting the
presence or absence of signals from terminal P1 periodically during
this interval, the voltage across the capacitor 405 is evaluated to
determine whether it is at 1.8 V or higher. When the voltage is
less than 1.8 V, the controller 401 outputs a control signal from
terminal P2, and turns switch 404 on for a prescribed time (for
example, approximately 1 .mu.s to approximately 80 .mu.s). If a
voltage higher than 1.8 V is held by the electrical double-layer
capacitor 403, then a portion of the charge held by the electrical
double-layer capacitor 403 moves via the switch 404 to the
capacitor 405, and so the voltage of the capacitor 405 rises to 1.8
V or higher. By thus periodically monitoring the terminal P1, the
of the capacitor 405 remains substantially in the vicinity of 1.8
V. As the voltage on the electrical double-layer capacitor 403
approaches 1.8 V, the above-described operation causes the extent
of the increase in the voltage of the capacitor 405 to become
smaller, and the switch 404 is turned on more frequently. When this
turning-on occurs at a frequency equal to or greater than a fixed
value (for example, once every two times monitored), the controller
401 adjusts the time over which the switch 404 is turned on to be
somewhat longer.
[0097] According to the above-described operation, the power supply
voltage of the controller 401 in this embodiment is always held at
a fixed value, so that the strength of signals transmitted from the
resonance circuit 410 can be held constant. Further, unnecessary
increases in the power supply voltage of the controller 401 are
avoided, so there is the further advantage that current consumption
is reduced.
[0098] A determination that the voltage on the electrical
double-layer capacitor 403 has fallen close to 1.8 V may be drawn
if the time which the switch 404 is turned on is set to a long
value (for example, 80 .mu.s), and the frequency with which the
switch 404 is turned on reaches or exceeds a constant value (for
example once every two times monitored). Under these circumstances,
the controller 401 transmits information (a charging request)
indicating that the power supply voltage of the position indicator
30 has fallen, as indicated by the operation of FIG. 5.
[0099] When a charging request indicating that the power supply
voltage has fallen is transmitted from the position indicator 30,
notification is provided to the user by an operation described
below. Upon receiving the notification, the user knows to mount the
position indicator 30 in the charger 50.
[0100] FIG. 6A shows an oblique, cut-away view of the configuration
of the charger 50 connected to the computer main unit 11. FIG. 6B
is a functional block diagram for operation of the charger 50. An
insertion opening 52 provides access to an area into which the
position indicator 30 is inserted. A support portion 53 supports
the position indicator 30. A power supply coil 54 is wound about
the support portion 53. The power supply coil 54 is connected to a
charging control circuit 55, and the charging control circuit 55 is
connected to the computer main unit 11. The charging control
circuit 55 generates an AC voltage at the same frequency as the
resonance frequency of the resonance circuit 410 by means of power
supplied by the computer main unit 11, and applies the AC voltage
to the power supply coil 54. In this manner, an AC magnetic field
is generated in the hollow portion of the support portion 53.
[0101] When the position indicator 30 is inserted into the
insertion opening 52 of charger 50, an induced voltage occurs in
the resonance circuit 410 of the position indicator 30. This
induced voltage is rectified by a diode 402, as best shown in FIG.
3, causing the electrical double-layer capacitor 403 to be
charged.
[0102] The position indicator 30 and the charger 50 which operate
as explained above contain the following circuits and units: a
charging circuit formed by the resonance circuit 410 and the diode
402; an information transmission unit formed by the resonance
circuit 410, controller 401 and capacitor 406; a voltage detection
unit formed by the voltage detector 407 and controller 401; a power
supply assistance unit formed by the capacitor 405, switch 404,
voltage detector 407 and controller 401; an AC magnetic field
generation unit formed by the power supply coil 54 and charging
control circuit 55; and a power transmission unit formed by the
resonance circuit 410.
[0103] In this embodiment, a power supply assistance unit is
provided such that operation is always normal when the voltage
across the electrical double-layer capacitor 403 is equal to or
greater than the operating voltage (here 1.8 V) of the controller
401. By providing a configuration which causes the voltage across
the electrical double-layer capacitor 403 to be increased, a
constant voltage can be supplied to the controller 401 even when
voltage across the electrical double-layer capacitor 403 falls
below the operating voltage of the controller 401.
[0104] FIG. 4 shows the internal configuration (tablet circuit 21)
of the tablet 20. The tablet circuit 21 is a circuit which receives
signals transmitted from the internal circuit 40 (FIG. 3) of the
position indicator 30, and detects the position indicated by the
position indicator 30. The tablet circuit 21 includes a CPU
(Central Processing Unit) 22 which exercises control over each of
the components illustrated in FIG. 4.
[0105] As best shown in FIG. 4, 21A and 21B are loop coil groups,
and are embedded in the input area 20A (FIG. 1) of the tablet 20.
In the input area 20A, a virtual X-Y orthogonal coordinate system
is set. The loop coil group 21A comprises a plurality of loop coils
arranged in the X direction, and the loop coil group 21B comprises
a plurality of loop coils arranged in the Y direction. Each of the
loop coils comprised by the loop coil groups 21A and 21B is
connected to a selection circuit 23. The selection circuit 23
selects one loop coil from among the loop coils of the loop coil
groups 21A and 21B, according to control of the CPU 22. An
amplifier 24 amplifies the signals received by the loop coils
selected by the selection circuit 23. A BPF (Band Pass Filter) 25
passes the component of the signal amplified by the amplifier 24 in
a specific frequency band. The signal component passed by the BPF
25 is converted into a voltage by a detector circuit 26, and is
input to a sample/hold circuit (S/H) 27. The voltage held by the
sample/hold circuit 27 is output to an AD conversion circuit (A/D)
28, and the CPU 22 reads the value output from the AD conversion
circuit 28, and stores the value as the level of the signal read
from the position indicator 30.
[0106] FIG. 5 is a timing chart showing transmission operations by
the position indicator 30 to transmit signals to the tablet 20. In
the figure, (A) illustrates output signals at terminal P0 of the
controller 401, (B) illustrates signals of the resonance circuit
410, (C) indicates the state of operation in the controller 401,
and (D) shows the contents of response data. The transmission
operation shown in FIG. 5 broadly comprises a continuous
transmission interval (times T1 to T2), and a data response
interval (T2 to T3).
[0107] In the continuous transmission interval from times T1 to T2,
a signal is output intermittently for a prescribed time (for
example 2 ms) or longer from terminal P0 of the controller 401.
This prescribed time is set to be sufficiently longer than the
transmission time per bit of the data response interval. Employing
this continuous transmission operation, an AC magnetic field is
radiated intermittently from the resonance circuit 410 during the
prescribed time. When the prescribed time elapses, the controller
401 halts output of the signal from terminal P0. After waiting for
a time, for example about 200 .mu.s, until the resonance circuit
signal has attenuated and has substantially vanished, the
controller 401 shifts into the operation of the data response
interval (T2 to T3). In the data response interval, 300 .mu.s are
allocated to one bit; here, 12 bits of data are transmitted. When
the response data is "0", a signal is output for 100 .mu.s from
terminal P0, and output is halted for the remaining 200 .mu.s. When
the response data is "1", output from terminal P0 is halted for 300
.mu.s. The 12 bits of data comprise nine bits of a stylus pressure
value, obtained when the controller 401 detects the discharge time
upon discharge through the resistance 424 of the
variable-capacitance capacitor 425, as best shown in FIG. 3, the
capacitance of which changes according to pressure applied to the
core 32; two bits of switch information, resulting from detection
of the operation states of the switches 33 and 34; and the
above-described one bit of charging request information.
[0108] Operation of the tablet circuit 21 when the position
indicator 30, operating in this manner, is placed on the input area
20A of the tablet, is described below.
[0109] First, the CPU 22 detects the received signal level while
switching in order among single loop coils in the loop coil group
21B (indicator detection step). Here, if the position indicator 30
is placed at a position which is closest to, for example, loop coil
Y7 among the loop coil group 21B, then the CPU 22 detects the
strongest signal level when loop coil Y7 is selected. Next, the Y7
loop coil for which the strongest signal level was detected is
selected, and the CPU 22 detects the signal level over a period
which is short compared with the data response period (300 .mu.s)
of the position indicator (continuous transmission detection step).
Here, when a signal at or above a prescribed level is detected
continuously over a longer interval than the data response period
(300 .mu.s), operation proceeds to the coordinate detection step
described below.
[0110] When a signal is detected at or above a prescribed level,
continuously over an interval longer than the data response period
(300 .mu.s), the position indicator 30 has entered into the
continuous transmission interval. A stabilized signal is radiated
from the position indicator 30 for a period of time.
[0111] The CPU 22 detects the approximate X-axis position in the
input area 20A. The CPU 22 detects the received signal level while
switching and selecting in order one loop coil from among the loop
coil group 21A (X-axis position detection step). Here, if the
position indicator 30 is placed in a position which is closest to
the loop coil X14 of the loop coil group 21A, then the CPU 22
detects the strongest signal level when the loop coil X14 is
selected. Next, the CPU 22 detects the signal level while switching
in order between a plurality of (for example, five) loop coils
centered on X14 and Y7. Here, a strong signal is detected from the
loop coils X14 and Y7 which are closest to the position indicator
30, and the further from these loop coils, the weaker is the
signal. The CPU 22 performs interpolation calculations between
coils based on the signal level distribution detected for the X
axis and Y axis, to accurately calculate the indicated position in
the input area 20A (coordinate calculation step). The interpolation
calculation is performed in a manner known in the art.
[0112] When the coordinate calculation step ends, the CPU 22 then
proceeds to a continuous transmission end detection step. The CPU
22 causes the selection circuit 23 to select Y7. In this state, the
CPU 22 detects the signal level continuously in periods as short as
possible (for example, at 5 .mu.s intervals). When continuous
transmission by the position indicator 30 ends, the signal from the
resonance circuit 41 is gradually attenuated. The CPU 22 detects
the fact that the reception level has fallen to or below a
prescribed value, and detects the timing with which continuous
transmission ends. When the reception level falls to or below the
prescribed value, the CPU 22 saves this time as the continuous
transmission end time, and then proceeds to a data reception
step.
[0113] Based on the continuous transmission end time, the CPU 22
performs signal detection 12 times with the same period as the data
response period of the position indicator 30 (300 .mu.s). In this
signal detection, the delay time from the continuous transmission
end time is adjusted in advance such that detection occurs
precisely when the signal generated in the resonance circuit 410
when there is a data "0" response from the position indicator 30 is
maximum.
[0114] In accordance with the above-described operation, the 12
bits of data transmitted from the position indicator 30 can be
accurately detected by the CPU 22 as the presence or absence of a
detection signal.
[0115] FIG. 7 is a block diagram showing the functional
configuration of the control system 100 of the computer main unit
11.
[0116] The control system 100, as best shown in FIG. 7, comprises a
CPU 101 which executes a program to perform data computation
processing; ROM (Read-Only Memory) 102 which stores programs, data
and similar; RAM (Random Access Memory) 103 which temporarily
stores programs executed by the CPU 101, data and similar used in
computation processing; a storage portion 104 which stores various
data; an input portion 105, to which a keyboard 13 and the tablet
20 are connected; a display portion 106 to which is connected the
monitor 12; and an interface portion 107. Each of these portions is
connected to a bus 108.
[0117] In this embodiment, the interface portion 107 is connected
to external equipment. In addition to performing functions to send
and receive various data to and from the external equipment, the
interface portion 107 has a function of supplying power to external
equipment. The charger 50 is connected to the interface portion
107, and the interface portion 107 supplies power to the charger 50
under control of the CPU 101.
[0118] Further, when a charging request, which requests charging of
the position indicator 30, is input from the tablet 20 via the
input portion 105, the CPU 101 executes charging control
processing, as best shown in FIG. 8, in concert with the tablet 20
and charger 50, to cause charging of the position indicator 30.
[0119] FIG. 8 is a flowchart showing charging control processing
executed in the system 10.
[0120] Charging control processing is started when the tablet 20
receives charging request data "1" transmitted from the position
indicator 30 (step S1). As explained above, charging request data
"1" is data indicating that the position indicator 30 requests
charging of the electrical double-layer capacitor 403. Upon
receiving the charging request data "1", the tablet 20 transmits a
charging request to the computer main unit 11 (step S2).
[0121] The CPU 101, upon receiving the charging request from the
tablet 20 (step S3), displays a charging request message on the
monitor 12 (step S4). This charging request message is a message
requesting that the user operating the position indicator 30 set
the position indicator 30 in the charger 50 in order to allow
charging to occur. The charging request message may for example be
displayed in a charging guidance screen 109 as shown in FIG. 9.
[0122] Next, the CPU 101 causes the start of the supply of power to
the charger 50 from the interface portion 107 (step S5), and, after
a prescribed time has elapsed, causes the supply of power to the
charger 50 to be stopped (step S6), and then returns to step
S1.
[0123] In this way, the charger 50 generates an AC magnetic field
in the vicinity of the coil 412 of the internal circuit 40 (FIG.
3), and thus the electrical double-layer capacitor 403 is charged.
Compared with a so-called secondary battery (nickel-cadmium battery
or similar), charging of the electrical double-layer capacitor 403
is completed in an extremely short amount of time (for example,
approximately 10 to 50 seconds). Hence, the time required for
supplying power to the charger 50 from the interface portion 107,
including the time required for the user to set the position
indicator 30 in the charger 50, is about two to about three minutes
or so.
[0124] In charging control processing, when the voltage across the
electrical double-layer capacitor 403 falls during use of the
position indicator 30 by the user, a display on the monitor 12
provides guidance to charge the position indicator 30, so that the
user can charge the position indicator 30 according to this
guidance. Charging of the position indicator 30 is performed in a
very short time simply by inserting the position indicator 30 into
the insertion opening 52 of the charger 50, so that the user
performs only an extremely simple operation, without diminution of
operability.
[0125] In the position input system of this embodiment, signals are
transmitted by power accumulated in the electrical double-layer
capacitor 403. Compared with known devices in which signals are
transmitted from the tablet, in the present embodiment strong
signals can be received by the tablet 20 from the position
indicator even under extremely low power consumption. Consequently,
strong signals can be initiated by and received from the position
indicator 30 even in the presence of noise from external sources,
and in particular noise from an integrated LCD, so advantageously
coordinate position and data can be detected with stability.
[0126] Further, the electrical double-layer capacitor 403 does not
require battery replacement as in the case of known devices which
incorporate primary batteries. Moreover, charging can be performed
in an extremely short time compared with other secondary batteries
having comparable capacities, so that the user is not
inconvenienced for a prolonged period while the position indicator
recharges.
[0127] When charging the electrical double-layer capacitor 403 of
the position indicator 30, charging can be performed extremely
easily, merely by setting the position indicator 30 in the charger
50. This charging is performed by causing the power supply coil 54
of the charger 50 to generate an AC magnetic field in the vicinity
of the coil 402. The power supply coils 54 and 412 do not make
contact. As a result of this contact-free configuration, there is
greater freedom of design of the charger 50 and position indicator
30, and durability can be further enhanced.
[0128] In the above first embodiment, an example was explained in
which, by displaying a charging guidance screen 109 or similar
notification on the monitor 12 the user is prompted to perform
charging. However, the invention is not limited to such a
configuration. For example, the need for charging can be reported
through the position indicator 30, tablet 20, or charger 50. This
reporting by the position indicator 30, tablet 20 and charger 50
may be performed independently, or may be performed in combination
with one another and optionally simultaneously, or may be performed
in place of a charging request message displayed on the monitor 12
in the above-described charging control processing, or may be
performed in conjunction with display of the charging request
message.
[0129] For example, as best shown in FIG. 10A, a light-emitting
portion 39 is provided in the case 31 of the position indicator 30.
When the controller 401 determines that charging of the electrical
double-layer capacitor 403 is necessary, the light-emitting portion
39 is caused to light or to flash under control of the controller
401. The light-emitting portion 39, for example, may be an LED
(light-emitting diode).
[0130] As another example, as shown in FIG. 10B, a light-emitting
portion 29 configured as an LED similarly to the light-emitting
portion 39 may be provided in the housing of the tablet 20. In this
example, when the tablet receives a charging request data "1"
transmitted from the position indicator 30, the light-emitting
portion 29 is caused to light under control of the CPU 22.
[0131] As a further example, as shown in FIG. 10C, a light-emitting
portion 59 configured as an LED similarly to the light-emitting
portions 29 and 39 may be provided in the housing 51 of the charger
50. The light-emitting portion 59 may be caused to light or to
flash while power is being supplied from the interface portion 107
of the computer main unit 11 to the charger 50. In this case, in
step S5 of the charging control processing (FIG. 8), the
light-emitting portion 59 is caused to light or to flash when power
supply to the charger 50 is started, and the light-emitting portion
59 is extinguished when power supply to the charger 50 is stopped
in step S6.
[0132] Alternatively, the light-emitting portion 59 may be caused
to light or to flash when power is received from the interface
portion 107 of the computer main unit 11, separately from the
charging control circuit 55 of the charger 50. In this case, when
in step S3 of the charging control processing, the CPU 101 receives
a charging request from the tablet 20, and power is supplied from
the interface portion 107 to the light-emitting portion 59.
[0133] In all of the above examples, the user is notified of the
need to charge the position indicator 30 through the lighting or
flashing of the light-emitting portion 59, permitting the user to
promptly charge the position indicator 30.
[0134] In the above first embodiment, an example was explained in
which the computer main unit 11 supplies power to the charger 50
when the charging request data transmitted from the position
indicator 30 is "1"; but the invention is not limited to such a
configuration. For example, control may be executed in which power
is supplied to the charger based on the time elapsed since the
previous charging. Below, such cases are explained as modified
examples 1 and 2 of this embodiment.
Modified Example 1
[0135] FIG. 11 is a flowchart showing charging control processing
in a modified example of the above first embodiment. The
configuration of this modified example is similar to that of the
computer system 10 of the above first embodiment, except for the
operation of charging control processing.
[0136] In the charging control processing shown in FIG. 11, the CPU
101 of the computer main unit 11 counts the time elapsed from the
previous charging of the position indicator 30 (step S11), and when
this elapsed time has reached a prescribed time (step S11: Yes), a
charging request message is displayed on the monitor 12 (step S12),
and causes the supply of power from the interface portion 107 to
the charger 50 to be started (step S13). Then, after a prescribed
time has elapsed, the CPU 101 stops the supply of power to the
charger 50 (step S14), returns to step S11, and counts the elapsed
time.
[0137] In this case, even when the tablet 20 has not received
charging request data from the position indicator 30, the user is
prompted to charge the position indicator 30. Hence when charging
request data is not received from the position indicator 30, the
user can still be informed of the need to charge the position
indicator 30. Situations in which the charging request data cannot
be received may include, for example, when the voltages on the
electrical double-layer capacitor 403 and capacitor 405 have fallen
to extremely low levels and the controller 401 cannot operate at
all, or when some obstacle exists or the distance between the
position indicator 30 and tablet 20 is too great, so that data
cannot be transmitted from the position indicator 30 to the tablet
20.
Modified Example 2
[0138] FIG. 12 is a flowchart showing charging control processing
in another modified example of the above first embodiment. The
configuration of this modified example is similar to that of the
system 10 of the above-described first embodiment, except for the
operation of charging control processing.
[0139] In the charging control processing shown in FIG. 12, the CPU
101 of the computer main unit 11 counts the time elapsed from the
previous charging of the position indicator 30 (step S21). When
this elapsed time has reached a prescribed time (step S21: Yes),
the CPU 101 determines whether the tablet 20 is able to receive
signals transmitted from the position indicator 30 (step S22).
[0140] When no signals transmitted from the position indicator 30
are being received by the tablet 20 (step S22: No), the controller
401 displays a charging request message on the monitor 12 (step
S23) and starts the supply of power from the interface portion 107
to the charger 50 (step S24). After a prescribed time has elapsed,
the controller 401 stops the supply of power to the charger 50
(step S25), and returns to step S21 to begin counting elapsed
time.
[0141] On the other hand, when after the prescribed time has
elapsed from the previous charging, signals from the position
indicator 30 are received by the tablet 20 (step S22: Yes), the
controller 401 determines whether signals received by the tablet 20
comprise the charging request data "1" (step S26). When the
charging request data "1" is present (step S26: Yes), the
controller 401 proceeds to step S23 and causes charging to be
performed. On the other hand, when the charging request data "1" is
not present (step S26: No), the controller 401 returns to step
S21.
[0142] In the example shown in FIG. 12, even when charging request
data is not received by the tablet 20 from the position indicator
30, the user can be prompted to charge the position indicator 30.
For example, even when charging request data cannot be received
from the position indicator 30, the user can be made to charge the
position indicator 30 to return to a state in which use is
possible. Further, when signals are transmitted from the position
indicator 30 to the tablet 20 and moreover there is no charging
request data "1" from the position indicator 30 even after the
prescribed time has elapsed from the previous charging, that is,
when adequate charge remains on the electrical double-layer
capacitor 403 in the position indicator 30, no charging is
performed, and so unnecessary charging can be avoided.
[0143] In the above first embodiment and modified examples,
configurations were explained in which the supply of power to the
charger 50 is started and stopped under control of the CPU 101.
However, the invention is not limited to such a configuration, and
for example a switch may be provided on the charger 50. Such a case
is explained as a second embodiment.
Second Embodiment
[0144] FIG. 13A shows an oblique, cross-sectional view of a charger
50A (stand) of a second embodiment of the invention, and FIG. 13B
is a functional block diagram for operation of the charger 50A.
[0145] The computer system 10 of this second embodiment has a
configuration common with that of the above first embodiment except
for the charger 50A shown in FIG. 13A, and so common portions are
omitted from the drawings and the detailed description
hereinbelow.
[0146] As best shown in FIG. 13A, the charger 50A of this second
embodiment is provided with a detection switch 56 in the portion
between the inner side of the insertion opening 52 and the inside
of the support portion 53. The detection switch 56 is configured so
as to move when pressure is applied, and an internal electrical
contact is closed upon movement of switch 52 to a closed
position.
[0147] As shown in FIG. 13B, the detection switch 56 is connected
to the charging control circuit 55. The charging control circuit 55
passes a current to the power supply coil 54 only in the state in
which the detection switch 56 is closed.
[0148] In this configuration, when the position indicator 30 (FIG.
2) is inserted into the insertion opening 52 of the charger 50A,
the detection switch 56 is pressed by the case 31, and current
begins to be supplied to the power supply coil 54. In this state,
an AC magnetic field is generated by the power supply coil 54 in
the vicinity of the position indicator 30, and an induced voltage
appears in the coil 412 (FIG. 3), so that the electrical
double-layer capacitor (FIG. 3) is charged. When the position
indicator 30 is removed from the insertion opening 52, current to
the power supply coil 54 is stopped. Hence, when charging the
position indicator 30, it is sufficient to insert the position
indicator 30 into the insertion opening 52, wait for a prescribed
length of time (for example, approximately 10 to 50 seconds), and
then remove the position indicator 30.
[0149] In this case, even when power is constantly supplied to the
charger 50A from the computer main unit 11, current is passed to
the power supply coil 54 only when the position indicator 30 is
actually set in the charger 50A and the position indicator 30 is
being charged, so that unnecessary power consumption can be
avoided. Further, there is no longer a need for the computer main
unit 11 to control current flow to the charger 50A, so that more
efficient control is possible.
[0150] In the above first and second embodiments and in the
modified examples, configurations were described in which the
position indicator 30 was charged by chargers 50, 50A; but a tablet
which integrates the functions of these chargers 50, 50A can be
used as explained below with regard to third and fourth embodiments
of the invention.
Third Embodiment
[0151] FIG. 14 is an oblique view showing the tablet 61 of a third
embodiment of the invention.
[0152] The computer system 10 of this third embodiment comprises
the tablet 61 shown in FIG. 14 in place of the tablet 20 and
charger 50 shown in FIG. 1. Except for this tablet 61, the
configuration of the computer system 10 is common to that of the
above first embodiment, and so common portions are omitted from the
drawings and the detailed description provided hereinbelow.
[0153] The tablet 61 shown in FIG. 14 has a configuration in which
an input area 61A is provided on the upper face of a substantially
planar housing. The tablet 61 incorporates an internal circuit 21
(FIG. 4) similar to that of the tablet 20, and in the input area
61A are embedded loop coil groups 21A, 21B. On the outside of the
input area 61A is positioned a charging portion 62 (stand) on the
upper face of the tablet 61. The charging portion 62 has an outer
casing which is substantially dome-shaped, and an insertion opening
63 is formed integrally in the upper end of this outer casing. The
insertion opening 63 has a diameter enabling insertion of at least
the tip portion of the position indicator 30 (FIG. 2), and is
connected to a hole extending to the interior of the charging
portion 62.
[0154] The charging portion 62 incorporates a power supply coil 54
(FIG. 6) and charging control circuit 55 (FIG. 6) similar to the
charger 50. The power supply coil 54 is wound around the outside of
the hole connected to the charging portion 62.
[0155] when current is supplied to the power supply coil 54
incorporated into the charging portion 62, by inserting the
position indicator 30 into the insertion opening 63, an AC magnetic
field is generated in the vicinity of the coil 412 (FIG. 3) of the
position indicator 30. The electrical double-layer capacitor 403
(FIG. 4) is charged by the current flowing in this coil 412 which
is induced by the AC magnetic field.
[0156] That is, the tablet 61 combines the functions of the tablet
20 for performing position input operations using the position
indicator 30 and the functions of the charger 50 to perform
charging of the position indicator 30. Hence, according to this
third embodiment, advantageously the computer system 10 can be
installed in a smaller space. Further, the computer main unit 11
and tablet 61 can be connected by what appears to be a single
cable, so that cable layout is simplified, thereby easing
installation.
Fourth Embodiment
[0157] FIG. 15 is an oblique view showing the configuration of the
tablet 65 of a fourth embodiment of the invention.
[0158] The computer system 10 of this fourth embodiment comprises
the tablet 65 shown in FIG. 15 in place of the tablet 20 and
charger 50 shown in FIG. 1. Except for this tablet 65, the
configuration of the computer system 10 is common to that of the
above first embodiment, and so common portions are omitted from the
drawings and detailed description provided hereinbelow.
[0159] The tablet 65 shown in FIG. 15 has a configuration in which
an input area 65A is provided on the upper face of a substantially
planar housing. The tablet 65 incorporates an internal circuit 21
(FIG. 4) similar to that of the tablet 20, and in the input area
65A are embedded loop coil groups 21A, 21B. On the outside of the
input area 65A is embedded a power supply coil 66 (AC magnetic
field generation unit) for the tablet 65. The power supply coil 66
is, for example, a loop coil positioned in a plane parallel to the
upper face of the tablet 65, and more specifically, is mounted by
means of a printed board or similar structure having a plurality of
layers.
[0160] The tablet 65 incorporates a charging control circuit 55
(FIG. 6) similar to that of the charger 50. The charging control
circuit 55 is connected to the power supply coil 66. Hence an AC
voltage is applied to the power supply coil 66 under control of the
charging control circuit 55, and an AC magnetic field appears in
the direction perpendicular to the plane of the power supply coil
66.
[0161] According to this configuration, by incorporating the
charging control circuit 55 in the tablet 65, when the tip of the
position indicator 30, that is, the coil 412 (FIG. 4), is brought
close to the power supply coil 66 when current is being supplied to
the power supply coil 66, an AC magnetic field is generated in the
vicinity of the coil 412. The electrical double-layer capacitor 403
(FIG. 4) is charged by the current flowing in the coil 412 induced
by this AC magnetic field. Hence merely by performing the simple
operation of, for example, standing or otherwise positioning the
position indicator 30 above the power supply coil 66, the position
indicator 30 can be charged.
[0162] Further, the tablet 65 combines the functions of the tablet
20 to perform position input operations using the position
indicator 30 and the functions of the charger 50 to charge the
position indicator 30. Consequently, the system 10 advantageously
can be installed in a smaller space. Further, the computer main
unit 11 and tablet 65 can be connected by what appears to be a
single cable, so that cable layout is simplified, and installation
is made easier.
[0163] It is of course possible to provide, by printing or other
means, a display on the upper face of the tablet 65 indicating the
location in which the power supply coil 66 is embedded, and to
provide guidance, in a charging request message displayed on the
monitor 12, for charging the position indicator 30 using this
printed display as a guide.
Fifth Embodiment
[0164] FIG. 16 is an oblique view showing the configuration of the
tablet-type computer 70 of a fifth embodiment of the invention.
[0165] The tablet-type computer 70 of this fifth embodiment is a
portable-type computer incorporating a battery (not shown) as a
power supply, and has functions similar to those of the systems 10
in the above first through fourth embodiments and in the modified
examples.
[0166] The tablet-type computer 70 incorporates the control system
100 of the computer main unit 11 in a substantially board-shaped
case 71. A liquid crystal display panel 72 (display device) is
positioned on the surface of the case 71, and below the liquid
crystal display panel 72 is housed an internal circuit 21 (FIG. 4)
incorporated within the tablet 20, with loop coil groups 21A, 21B
embedded. That is, the liquid crystal display panel 72 also
functions as an input area, and position input operations using the
position indicator 30 can be performed on the liquid crystal
display panel 72.
[0167] Further, the functional configuration of the tablet-type
computer 70 is similar to that of the control system 100 of the
computer main unit 11 in FIG. 7, and various basic control programs
and application programs are executed based on input operations by
the position indicator 30.
[0168] An indicator housing portion 73 which houses the position
indicator 30 (FIG. 2) is formed in the case 71 of the tablet-type
computer 70. The indicator housing portion 73 is a tube-shaped
structure, linked to an insertion opening 74 which opens onto a
side face of the case 71. The depth and inner diameter of the
insert opening 74 are sized to enable housing of the case 31 of the
position indicator 30. Hence by inserting the position indicator 30
into the insertion opening 74, the position indicator 30 can be
housed within the indicator housing portion 73. Further, a power
supply coil 75 (AC magnetic field generation unit) is wound around
the outside of the region of the indicator housing portion 73
housing the tip portion of the position indicator 30. An AC voltage
is applied to the power supply coil 75 by a charging control
circuit, not shown. By use of this AC voltage, an AC magnetic field
is generated within the indicator housing portion 73.
[0169] In the tablet-type computer 70 configured as described above
and illustrated in FIG. 16, when the position indicator 30 is not
in use and is housed in the indicator housing portion 73, the
position indicator 30 is charged. Hence the position indicator 30
is maintained in a constantly charged state, and there is the
advantage that the position indicator 30 can be used simply by
removal from the indicator housing portion 73. Further, while there
is a limit to the capacity of the battery in the tablet-type
computer 70, if, as in the above first embodiment and modified
examples, current is supplied to the power supply coil 75 only when
the position indicator 30 must be charged, power consumption can be
greatly reduced, with no effect on the availability for use of the
tablet-type computer 70.
[0170] In the tablet-type computer 70, the position indicator 30
and the loop coil groups 21A, 21B are opposed on either side of the
liquid crystal display panel 72, and there is the possibility that
signals transmitted from the position indicator 30 may be affected
by electromagnetic noise. But because, as described above, the
position indicator 30 can transmit signals efficiently and at high
power, signals from the position indicator 30 can be received
satisfactorily by the loop coil groups 21A, 21B. As a result,
positions input using the position indicator 30 can be detected
precisely and with stability, and satisfactory operability is
secured.
[0171] In the above first through fifth embodiments and the
modified examples, examples were explained in which a method of
generating an AC magnetic field in the vicinity of the coil 412 was
used as the method of charging the electrical double-layer
capacitor 403 incorporated within the position indicator 30. But
the invention is not limited to such a method. For example, exposed
terminals electrically connected to both ends of the electrical
double-layer capacitor 403 may be provided in the case 31, so that
by connecting the exposed terminals to a power supply device
external to the position indicator 30, the electrical double-layer
capacitor 403 can be charged.
[0172] Further, in the above first through fifth embodiments and
the modified examples, an electrostatic coupling method may be used
to detect the position of the position indicator 30 using the
tablet 20.
[0173] Below, an example of this is explained as a sixth
embodiment.
Sixth Embodiment
[0174] FIG. 17 shows the configuration of the internal circuit 43
of the position indicator of a sixth embodiment. FIG. 18 shows the
configuration of the internal circuit 44 in the tablet of the sixth
embodiment. In the internal circuit 43 and internal circuit 44
shown in FIG. 17 and FIG. 18, respectively, portions which are
configured similarly to those in the internal circuit 40 (FIG. 3)
and the internal circuit 21 (FIG. 4) are assigned the same symbols,
and explanations provided above are not repeated below.
[0175] In this sixth embodiment, the position indicator 30
incorporating the internal circuit 43 and the tablet 20
incorporating the internal circuit 44 perform detection of
indicated positions by electrostatic coupling. A non-equilibrium
signal voltage is applied as a reference to the tip conductor 434
of the conductive core 435, as best shown in FIG. 17, which
protrudes from the tip of the case 31 (FIG. 2) in the position
indicator 30. When an operation is performed in which this
conductive core 435 is brought into contact with the surface of the
tablet 20, that is, with the input area 20A (FIG. 1), loop coils in
the tablet 20 are electrostatically coupled with the conductive
core 435. Here, a potential difference appears at each loop coil in
the tablet 20, and these potential differences correspond to the
distance from the conductive core 435, so that the position of the
conductive core 435 can be detected based on the potential
differences of a plurality of loop coils.
[0176] The configuration of the internal circuit 43 in FIG. 17 is
explained.
[0177] In the internal circuit 43, a voltage conversion circuit 431
(voltage supply assistance unit) is connected in series between the
electrical double-layer capacitor 403 and the power supply terminal
Vcc of the controller 401. The voltage conversion circuit 431 is a
circuit which converts the voltage across the electrical
double-layer capacitor 403 and supplies a power supply voltage to
the Vcc terminal of the controller 401. If the rated power supply
voltage of the controller 401 is 1.5 V, and if the voltage across
the electrical double-layer capacitor 403 is 2.5 V, then the
voltage conversion circuit 431 steps down this voltage to 1.5 V,
and applies the stepped-down voltage to the power supply terminal
Vcc. Also, when for example the voltage across the electrical
double-layer capacitor 403 falls to 0.5 V, the voltage conversion
circuit 431 steps up this voltage to 1.5 V and supplies the
stepped-up voltage to the power supply terminal Vcc.
[0178] Control signals from the terminal P1 of the controller 401
are input to the voltage conversion circuit 431, and signals can be
transmitted from the voltage conversion circuit 431 to the terminal
P2 of the controller 401. When a control signal is input from the
terminal P1 of the controller 401, the voltage conversion circuit
431 detects the voltage across the electrical double-layer
capacitor 403, and outputs a signal indicating the voltage value to
the terminal P2. In this manner, the controller 401 can determine
whether charging of the electrical double-layer capacitor 403 is
necessary.
[0179] In the internal circuit 43, a charging terminal 432 (power
transmission unit) is connected to the electrical double-layer
capacitor 403. This charging terminal 432 comprises a contact point
exposed from the case 31 (FIG. 2) of the position indicator 30.
This contact point is connected to a power supply device external
to the computer system 10. Hence the electrical double-layer
capacitor 403 is charged by this external power supply device.
[0180] Upon receiving a power supply voltage from the electrical
double-layer capacitor 403, the controller 401 applies a sinusoidal
voltage from the terminal P0 to the conductive core 435 protruding
from the tip of the case 31 (FIG. 2), based on a clock pulse
generated by an oscillator 421. A capacitor 433 is connected in
series between the terminal P0 and the conductive core 435, and
only a sine-wave component is applied to the conductive core 435.
Here, a tip conductor 434 is positioned on the periphery of the
conductive core 435, and this tip conductor 434 is connected to a
GND terminal of the controller 401.
[0181] On the other hand, in the internal circuit 44 incorporated
within the tablet 20, each of the loop coils of the loop coil
groups 21A, 21B is connected to the multiplexer 444, and this
multiplexer 444 is connected to a differential amplifier 441,
band-pass filter (BPF) 442, and control portion 443, as best shown
in FIG. 18.
[0182] The differential amplifier 441 amplifies the differences in
the input signals from each loop, connected via the multiplexer
444, and outputs the result to the band-pass filter 442. After
removal of noise components from this signal by the band-pass
filter 442, the signal is input to the control portion 443. The
control portion 443 detects the position of the conductive core
435, that is, the position indicated using the position indicator
30, based on the input signal.
[0183] In this way, the invention can be applied in cases of
position detection using an electrostatic coupling method. In such
cases also, the internal circuit 43 of the position indicator 30
has an electrical double-layer capacitor 403, and this electrical
double-layer capacitor 403 can be used as a power supply to drive
the controller 401, so that sufficiently strong signals can be
transmitted from the internal circuit 43, and moreover battery
replacement and other troublesome maintenance is unnecessary.
[0184] Further, when a charging terminal 432 to charge the
electrical double-layer capacitor 403 is provided, as in the sixth
embodiment, by connecting a device which supplies a prescribed DC
voltage as an external power supply device to the charging terminal
432, the electrical double-layer capacitor 403 can be charged
rapidly. As explained above, the electrical double-layer capacitor
403 can be charged in an extremely short time, and so the external
power supply device need only be connected to the charging terminal
432 for a short time. Hence charging is easily performed, and there
is no need to provide a special mechanism or the like to maintain
contact between the external power supply and the charging terminal
432, and the device can easily be realized at extremely low
cost.
[0185] In this sixth embodiment, the loop coil groups 21A, 21B may
be embedded in the tablet 20 as described above; however, loop
coils which do not detract from the viewability of the liquid
crystal screen of the tablet 20 may be positioned at the surface of
the tablet 20. In this case, there is the advantage that the
position indicated by the position indicator 30 incorporating the
internal circuit 43 can be detected more stably and reliably.
[0186] In the above first through sixth embodiments and the
modified examples, the position indicator 30 has been illustrated
and discusses as having a pen-type case 31. The invention is not
limited to such a configuration, and for example a configuration
may be employed using an air-brush type, digitizer cursor type, or
mouse-type position indicator or similar, a smaller indicator with
a ring shape, or other suitable configurations and designs.
Moreover, the position of the coil 412 in the position indicator
30, the position, shape and number of the switches 33 and 34, and
other structural features are arbitrary and may be modified without
departing from the principals of the invention, as may other
details of the configuration be modified.
Seventh Embodiment
[0187] FIG. 19 of the accompanying drawings is a block diagram
showing an arrangement of a position pointing device according to a
seventh embodiment of the present invention. In the embodiments
which will follow, it is assumed that the position pointing device
has two kinds of functions: a pen-point function, characterized by
an ability to write information, and an eraser function,
characterized by an ability to erase written information. These
writing and erasing functions are applicable to a variety of
different colors and stroke thicknesses. Although the below
description is restricted to dual-function position pointing
devices in the interest of brevity, it should be understood that
the position pointing devices may be capable of performing three or
more functions. It should also be understood that other functions
may be practiced in addition to or as alternatives of writing and
erasing.
[0188] As shown in FIG. 19, the position pointing device according
to the seventh aspect of the present invention includes at its
pen-point side a signal transmission unit composed of a position
pointing coil 211 and an oscillation circuit 212 with an
oscillation frequency f1. This position pointing device further
includes at its eraser side a signal transmission unit composed of
a position pointing coil 213 and an oscillation circuit 214 with an
oscillation frequency f2. Also, the position pointing device
includes a timing circuit (oscillator) 215 to generate a
square-wave signal with a predetermined frequency of which the duty
ratio is nearly 50%. An output signal from the timing circuit 215
is directly supplied to the oscillation circuit 212 as a driving
signal, and the output signal is also supplied through an inverter
216 to the oscillation circuit 214.
[0189] In this circuit, electric power is supplied from a battery
(not shown) to respective units of the circuit to permit operation
of the respective units. The timing circuit 215 is adapted to
generate a clock signal with a frequency having a period
sufficiently longer than the time required by the tablet side to
detect coordinates of the position pointed by the position pointing
device, for example, a clock signal with a frequency of
approximately 100 Hz. Thus, when the clock signal from the timing
circuit 215 is held at a high level, the oscillation circuit 212 on
the pen-point side may be operated. When on the other hand the
clock signal is held at a low level, the oscillation circuit 214 on
the eraser side may be operated. Accordingly, in this circuit, it
is possible to reduce power consumption of the pen-point side or
the eraser side, either of which may be alternately de-energized
when not in operation so that only one side is energized at a
time.
[0190] More specifically, in the seventh embodiment of the present
invention, primary factors affecting power consumption are electric
power consumed by the oscillation circuit 212 and the position
pointing coil 211 connected to the oscillation circuit 212, and
electric power consumed by the oscillation circuit 214 and the
position pointing coil 213 connected to the oscillation circuit
214. On the other hand, according to the seventh embodiment of the
present invention, because the pen-point side and the eraser side
are controlled so as to alternately operate, the side not in use is
de-energized, and power consumption can be decreased. As a result,
an operator is able to freely select the pen-point or the eraser
when the position pointing device is in use, while reducing power
consumption at the non-selected side. In this manner, the life of
the battery can be prolonged.
Eighth Embodiment
[0191] Next, FIG. 20 shows an arrangement of a position pointing
device according to an eighth embodiment of the present invention.
As shown in FIG. 20, the position pointing device according to the
eighth embodiment of the present invention includes at its
pen-point side a resonance circuit 221 with a predetermined
resonance frequency f2. The resonance circuit 221 is composed of a
coil 221a and a capacitor 221b. Also, the position pointing device
of FIG. 20 includes at its eraser side a resonance circuit 222 with
a predetermined resonance frequency f0. The resonance circuit is
composed of a coil 222a and a capacitor 222b. A microprocessor,
generally depicted by reference numeral 223 in FIG. 20, includes a
ROM (read-only memory) and a RAM (random-access memory), although
not shown, and this microprocessor 223 is able to operate in
accordance with previously-set predetermined programs.
[0192] Also, an oscillator 224 with the above-described frequency
f0 is connected to the microprocessor 223 to generate a driving
clock signal of the microprocessor 223 and signals with the
frequency f0 which are radiated from the resonance circuits 221 and
222. As a result, while the signal with the above-described
frequency f0 is outputted from a terminal P0 of the microprocessor
223 at predetermined timing, the output signal from the terminal P0
is supplied at any one time to only one of the resonance circuit
221 of the pen-point side and the resonance circuit 222 of the
eraser side.
[0193] In the embodiment illustrated in FIG. 20, detecting units
226 and 227 are adapted to detect the pressure that the operator
puts on the stylus pen when touching the position detecting tablet
with the stylus pen. This pressure will hereinafter be simply
referred to as a "stylus pressure" and the detecting units 226 and
227 will hereinafter be referred to as a "stylus pressure detecting
unit 226" and a "stylus pressure detecting unit 227," respectively.
The stylus pressure detecting units 226 and 227 are connected to
the microprocessor 223. These stylus pressure detecting units 226
and 227 may output detected stylus pressures in the form of 8-bit
digital values and the microprocessor 223 may be operated so as to
regularly read these digital values. The microprocessor 223 outputs
a signal to control an analog switch 225 to a terminal P1 based on
the read signals. In FIG. 20, reference numerals 228 and 229 denote
coupling capacitors, respectively.
[0194] Consequently, the analog switch 225 supplies a signal to the
pen-point side when the signal from the terminal P1 of the
microprocessor 223 is held at a low level, and analog switch 225
supplies a signal to the eraser side when the signal from the
terminal P1 is held at a high level. In this circuit, respective
units are supplied with and energized by electric power from a
battery, not shown. Accordingly, also in this circuit, power
consumption by the sides which are alternately de-energized can be
reduced. Thus, the operator can freely choose between the pen-point
side and the eraser side when the position pointing device is in
use. Also, power consumption can be decreased and life of the
battery can be prolonged by de-energizing the unselected (pen-point
or eraser) side.
[0195] FIG. 21 is a cross-sectional view partially in perspective
showing a specific arrangement of a position pointing stylus pen
which may serve as the above-mentioned position pointing device of
the eighth embodiment of the present invention. As shown in FIG.
21, a pen-point 230 is provided at the lower left end portion of
FIG. 21 and an eraser 231 is provided at the upper right end
portion of FIG. 21. It should be noted that the illustrated
pen-point 230 and eraser 231 imitate writing instrument components.
The pen point 230 and eraser are preferably formed of resin
materials. Coils 221a and 222a, which serve as position pointing
coils, are provided in the vicinity of the pen-point 230 and eraser
231, respectively.
[0196] The pen-point 230 and eraser 231 are connected at their
inner end portions to the stylus pressure detecting units 226 and
227, respectively. Stylus pressures obtained when the pen-point 230
and the eraser 231 are depressed are transmitted to the stylus
pressure detecting units 226 and 227 and thereby the stylus
pressures can be detected. Then, the thus detected stylus pressures
are converted into 8-bit digital values, for example, and supplied
to the microprocessors 223 (not shown in FIG. 21) provided on a
circuit board 232. It should be noted that the illustrated position
pointing stylus pen includes a built-in battery 233 to supply
electric power to suitable units such as the microprocessor 223 on
the circuit board 232.
[0197] Operations of the position pointing device according to the
eighth embodiment of the present invention will be described with
reference to waveform diagrams of FIGS. 22A, 22B and 22C.
[0198] FIG. 22A is a diagram of a waveform of signals to which
reference will be made in explaining operations of the position
pointing device when the operator operates the pen-point side. The
microprocessor 223 reads output data from the stylus pressure
detecting unit 226. If the stylus pressure of the pen-point side is
greater than a predetermined stylus pressure, then the
microprocessor 223 fixes the terminal P1 at a low level and outputs
a signal from the terminal P0 at timing shown in FIG. 22A. This
signal outputted from the terminal P0 is a signal with a frequency
nearly equal to the resonance frequency f0 of the resonance circuit
221 as mentioned hereinbefore. This signal is intermittently
transmitted at the cycle of 150 .mu.s after the continuous
transmission period in which the above signal is continuously
transmitted during the period longer than a constant period.
[0199] This intermittent transmission period occurs 9 times per
cycle in which 1 bit to distinguish the pen-point side and the
eraser side is added to 8 bits of stylus pressure information,
i.e., 9 bits in total are transmitted consecutively. As shown in
FIG. 22A, according to this embodiment, a signal is transmitted if
transmitted data is "0" and a signal is not transmitted if
transmitted data is "1". Thus, "0" or "1" may be represented.
Accordingly, the tablet side is able to receive signals in
accordance with these timings and it is able to detect transmitted
data from the position pointing device in response to "0" obtained
if a signal is detected and "1" obtained if a signal is not
detected.
[0200] Also, FIG. 22B is a diagram of waveforms of signals to which
reference will be made in explaining operations of the position
pointing device when the operator operates the eraser side. The
microprocessor 223 reads output data from the stylus pressure
detecting unit 227. If the stylus pressure of the eraser side is
greater than a predetermined stylus pressure, then the
microprocessor 223 fixes the terminal P1 at a high level and
outputs a signal from the terminal P0 at timing shown in FIG. 22B.
This signal is supplied to the resonance circuit 222 (FIG. 2) at
exactly the same timing as that shown in FIG. 22A and then it is
radiated. The operations shown in FIG. 22B differ from the
operations of the pen-point side shown in FIG. 22A only in that the
final bit of the transmitted data is "1".
[0201] Consequently, the tablet side is able to determine that the
received result of this final data is "1" and further is able to
recognize that the received signal should be transmitted from the
eraser side.
[0202] FIG. 22C is a diagram of signal waveforms to which reference
will be made in explaining operations of the position pointing
device when the stylus pressure detects, for both the pen-point
side and the eraser side, results that are less than the
predetermined value. The position pointing device may alternately
carry out the operations of the pen-point side (FIG. 22A) and the
operations of the eraser side (FIG. 22B) by alternately switching
the terminal P1 to the high level and the low level. However, 8
bits of stylus pressure information shown in FIG. 22C are all
"0".
[0203] As described above, according to this embodiment, because
the one-bit portion of the signal is intermittently transmitted
after the continuous transmission period in which the 8-bit portion
of the signal is continuously transmitted during a time period
longer than the constant time, the tablet side is able to easily
operate with timing matched with that of the position pointing
device. Also, the pen-point side and the eraser side can be
distinguished from one another by only one frequency. The pen-point
side and the eraser side are alternately operated when the operator
operates neither the pen-point side nor the eraser side.
Accordingly, the tablet side is able to detect which of the
pen-point side or the eraser side is operated irrespective of which
side is operated first and hence the operator can choose from the
pen-point and the eraser freely when the position pointing device
is in use.
[0204] In the above-mentioned position pointing device, a primary
source of the consumption of electric power is the electric power
supplied to and consumed by the resonance circuits 221 and 222 from
the terminal P0 of the microprocessor 223 through the analog switch
225. This problem is largely overcome by the present embodiment.
Because at any time only one of the resonance circuits 221 or 222
is energized and the other is de-energized under control of the
analog switch 225, power consumption of the position pointing
device can be decreased and life of the battery can be
prolonged.
[0205] When the pen-point side stylus pressure and the eraser side
stylus pressure both are less than a predetermined value, the
position pointing device may, after a given or predetermined time
period, move to the alternate operations mode shown in FIG. 22C.
The reason for movement to the alternate operations mode is that,
when the position pointing device is in ordinary use, the operator
is unable to suddenly switch the pen-point side to the eraser side.
In actual manipulation, the operator may frequently and repeatedly
use the position pointing device in such a manner as to operate the
pen-point side or the eraser side with or without stylus pressure
greater than the constant value. As a result of the alternate
operations mode, the operator is able to operate the position
pointing device smoothly.
[0206] Further, while the pen-point side and the eraser side are
switched under control of the analog switch 224 in this embodiment
of the present invention, the present invention is not limited
thereto. For example, the microprocessor 223 may include two
terminals by which the signal with the frequency f0 can be
outputted and the signal may be outputted from either one of the
two terminals. In that case, the microprocessor 223 may switch
therein the outputs to the two terminals by using the signal
outputted to the terminal P1. In this case, extra analog switch 225
need not be provided and the microprocessor 223 may have the same
number of terminals as sides.
[0207] While switching between the pen-point side and the eraser
side is based on detections of the stylus pressures in the
above-described eighth embodiment of the present invention, the
present invention is not limited thereto. Switching can be switched
based on other detectors, as described below.
Ninth Embodiment
[0208] FIG. 23 shows an arrangement of a position pointing device
according to a ninth embodiment of the present invention using
touch-sensitive sensors as the above-mentioned detectors. In FIG.
23, elements and parts identical to those of FIG. 20 are denoted by
identical reference numerals and therefore the description of
common features is not repeated hereinbelow.
[0209] Specifically, as shown in FIG. 23, the position pointing
device according to this ninth embodiment includes electrodes 234
and 235 serving as touch-sensitive sensors, and square-wave output
signals are supplied from the terminals P2 and P4 of the
microprocessor 236 to these electrodes 234 and 235, respectively.
The electrodes 234 and 235 are connected to terminals P3 and P5,
respectively, of the microprocessor 236 and thereby electric
potential is detected. Also in this circuit, electric power is
supplied from a battery, not shown, and thereby respective units of
the microprocessor 236 and the like can be operated.
[0210] Examples of the operation of this ninth embodiment of the
present invention are described below. If the operator's hand is
not near the electrode 234, then the square-wave signal outputted
from the terminal P3 is slightly deteriorated in waveform, as shown
in FIG. 24A. This deterioration is detected at the terminal P3. On
the other hand, if the operator's hand is near the electrode 234,
then the square-wave signal outputted from the terminal P2 is
considerably deteriorated in waveform, as shown in FIG. 24B, and
the deterioration is detected at the terminal P3. Accordingly, it
is possible for the microprocessor 236 by analyzing the change of
the waveform to determine which of the electrodes 234 and 235 is
near the hand of the operator.
[0211] FIG. 25 is a perspective view showing an example of a
position pointing stylus pen 239 serving as the above-mentioned
position pointing device of the ninth embodiment of the present
invention. Specifically, as shown in FIG. 25, the position pointing
stylus pen 239 includes the above-mentioned electrodes 234 and 235
provided near the pen-point 230 and the eraser 231, respectively.
The electrode 234 is positioned where the fingers of the operator
grip the position pointing stylus pen 239 for writing mode, and the
electrode 235 is situated where the fingers of the operator grip
the position pointing stylus pen 239 for erasing mode. The
remainder of the inside structure of this position pointing stylus
pen 239 is substantially equivalent to the position pointing stylus
pen described above, e.g., in which the microprocessor 236 is
provided on the circuit board 235, with the exception that the
stylus pressure detecting units 226 and 227 present in the
arrangement shown in FIG. 21 are excluded and therefore need not be
illustrated and described with respect to this embodiment.
[0212] Accordingly, in the ninth embodiment of the present
invention, when the operator operates the position pointing device
239 to employ the pen-point 230 or the eraser 231, the location at
which the operator's fingers grip the device 239, i.e., near the
electrode 234 or 235, determines the side of the device 239 which
is being used on the tablet. As a result, the position pointing
device 239 can execute processing operations similar to those
described above with reference to FIGS. 22A, 22B, and 22C. It
should be noted that the direction of the pen-point 230 or the
eraser 231 can be determined by changing the oscillation
frequency.
Tenth Embodiment
[0213] Further, FIG. 26 is a block diagram showing an arrangement
of a position pointing device according to a tenth embodiment of
the present invention. In the following description with reference
to FIG. 26, elements and parts identical to those of FIG. 20 are
denoted by identical reference numerals.
[0214] Specifically, as shown in FIG. 26, the pen-point side
includes the resonance circuit 221 with the predetermined resonance
frequency f0. The resonance circuit 221 includes the coil 221a and
the capacitor 221b. The eraser side includes the resonance circuit
222 with the predetermined frequency f0. The resonance circuit 222
includes the coil 222a and the capacitor 222b. Further, a
microprocessor, generally depicted by reference numeral 240 in FIG.
26, includes a ROM (read-only memory) and a RAM (random-access
memory), although not shown. The microprocessor 240 can be operated
in accordance with previously-set predetermined programs.
[0215] Also, the oscillator 224 with the above-described frequency
f0 is connected to this microprocessor 240 to generate a driving
clock signal of the microprocessor 240 and to generate the signal
with the frequency f0 which is to be radiated from the resonance
circuits 221 and 222. As a consequence, the signals with the
above-described frequency f0 are outputted from the terminals P0
and P6 of the microprocessor 240 at predetermined timings, and the
output signals from these terminals P0 and P6 are supplied through
capacitors 228 and 229, respectively, to the pen-point side
resonance circuit 221 and the eraser side resonance circuit 222,
respectively.
[0216] Further, capacitors 241 and 242 are respectively connected
to the above-mentioned capacitors 228 and 229, and analog switches
243 and 244 are respectively connected to the capacitors 241 and
242 in series. The analog switches 243 and 244 are driven under
control of the signals from the terminals P1 and P7 of the
microprocessor 240. It should be noted that the analog switches 243
and 244 are respectively energized when the signals from the
terminals P1 and P7 of the microprocessor 240 are held at a high
level.
[0217] The microprocessor 240 is connected to the stylus pressure
detecting unit 226 for detecting the stylus pressure obtained when
the operator operates the position pointing device at its pen-point
side. The microprocessor 240 is also connected to the stylus
pressure detecting unit 227 for detecting the stylus pressure
obtained when the operator operates the position pointing device at
its eraser side. These stylus pressure detecting units 226 and 227
each are adapted to output detected stylus pressures in the form of
8-bit digital values, and the microprocessor 240 is adapted to
regularly read these values. The microprocessor 240 outputs signals
to control the analog switches 243 and 244 to the terminals P1 and
P6 based on the read out signals.
[0218] When the signal from the terminal P1 of the microprocessor
240 is held at a low level, the analog switches 243 and 244 allow
the capacitors 228 and 241 to be connected in parallel to each
other to thereby raise the signal supplied to the resonance circuit
221 of the pen-point side in level. When the signal from the
terminal P7 of the microprocessor 240 is held at a low level, the
analog switches 243 and 244 allow the capacitors 229 and 242 to be
connected in parallel to each other to thereby raise the signal
supplied to the resonance circuit 222 of the eraser side in level.
It should be noted that, also in the circuit shown in FIG. 26,
electric power for operation of the units is supplied from a
battery (not shown) to the respective units.
[0219] Operations of the position pointing device having the
above-mentioned arrangement according to the tenth embodiment of
the present invention will be described below. The signal with the
frequency f0 is outputted from the terminal P0 of the
microprocessor 240 at the same timing as that shown in FIG. 22A,
and the signal is supplied through the capacitor 228 to the
resonance circuit 221. In a like manner, the signal with the
frequency f0 also is outputted from the terminal P6 of the
microprocessor 240 at the same timing as that shown in FIG. 22B and
the signal is supplied through the capacitor 229 to the resonance
circuit 222. The signals from these terminals P0 and P6 are
outputted at the same time and the signal with the frequency f0 is
constantly supplied to the resonance circuits 221 and 222.
[0220] Then, in this embodiment, the detected result obtained by
the stylus pressure detecting unit 226 is transmitted from the
terminal P0 and the detected result obtained by the stylus pressure
detecting unit 227 is transmitted from the terminal P6. While the
signals are transmitted from both of the pen-point side and the
eraser side, the tablet is able to detect a signal with the higher
level from either the pen-point side or the eraser side.
[0221] In this embodiment, the capacitor 241 is connected in
parallel to the capacitor 228 through the analog switch 243.
Similarly, the capacitor 242 is connected in parallel to the
capacitor 229 through the analog switch 244. Further, the
microprocessor 240 regularly reads an output value from the stylus
pressure detecting unit 226 that detects pressure of the pen-point
applied when the operator operates the position pointing device at
its pen-point side, and an output value from the stylus pressure
detecting unit 227 that detects pressure of the eraser applied when
the operator operates the position pointing device at its eraser
side.
[0222] Accordingly, if the stylus pressure of the pen-point side
(output value from the stylus pressure detecting unit 226) is
greater than a predetermined value, then the microprocessor 240
sets the terminal P1 to a high level to energize the analog switch
243. As a result, capacitive coupling generated when the signal
outputted from the terminal P0 is supplied to the resonance circuit
221 is increased. Power of the signal transmitted from the
resonance circuit 221 is thereby increased.
[0223] On the other hand, if the stylus pressure of the eraser side
(output value from the stylus pressure detecting unit 227) is
greater than a predetermined value, then the microprocessor 240
sets the terminal P7 to a high level to energize the analog switch
244. As a result, capacitive coupling generated when the signal
outputted from the terminal P6 is supplied to the resonance circuit
222 is increased. Power of the signal transmitted from the
resonance circuit 222 is thereby increased.
[0224] Accordingly, in this embodiment, transmission power of the
operated side can be increased by the aforementioned operations and
hence it is possible for the tablet side to detect a signal stably.
Also, because power of the side which is not operated can be
suppressed to the minimum, power consumption can be decreased and
life of the battery can be prolonged. It should be noted that, if
the stylus pressure of one side is greater than a predetermined
value, then transmission of a signal from the other side may be
stopped completely.
[0225] However, in this embodiment, if transmission of a signal
from one side is stopped completely, then when the position
pointing device is quickly switched in operation from the pen-side
to the eraser side or vice versa, a problem arises. Specifically,
the tablet side becomes unable to detect a signal obtained
immediately after switching from one side to another, because the
side switched to is not sending any signal. That is, the position
pointing device experiences a delay in the recognition of the
switch operation. However, if a signal is transmitted with small
power from the side not in operation, then the position pointing
device can manage the above-mentioned quick switching of operation
and hence the device can recognize switching of operation
immediately. It should be noted that, although stability of
detected coordinates is lowered during the first very short time
period, stability of detected coordinates can be improved as the
position pointing device transitions to ordinary power.
Eleventh Embodiment
[0226] FIG. 27 is a block diagram showing arrangements of a
position input system and a computer system according to an
eleventh embodiment of the present invention. The position input
system and computer system of FIG. 27 are compatible with the
position pointing devices of various embodiments described above,
including, but not necessarily limited to, the seventh to tenth
embodiments.
[0227] As best shown in FIG. 27, the position detecting apparatus
according to this embodiment includes a sensor coil group 201
composed of a plurality of loop coils, for example. In this sensor
coil group 201, in order to detect the position in the X-axis
direction and the position in the Y-axis direction, long sides of
loop coils (shown by only lines for simplicity) for effecting
electromagnetic induction are provided so as to cross each other as
shown in FIG. 27. It should be noted that solid-line (X-axis) loop
coils and broken-line (Y-axis) loop coils in FIG. 27 are provided
on different layers. The position pointing pen 239 having the
above-mentioned pen-point 230 and eraser 231 is moved close to the
sensor coil group 201 when this position input system is in
use.
[0228] Also, a plurality of loop coils forming the sensor coil
group 201 is sequentially provided in an overlapping fashion such
that wirings of coils are provided at a predetermined pitch.
Further, end portions of the loop coils in each layer are connected
to a selecting circuit 204X or a selecting circuit 204Y and hence
those loop coils are sequentially selected, scanned and driven by
the selecting circuit 204X or 204Y. It should be noted that the
selecting circuit 204X or 204Y may select those loop coils in
accordance with a control signal from a control circuit 205.
Accordingly, the control circuit 205 is able to constantly
recognize the position of the loop coil selected within the sensor
coil group 201.
[0229] A signal received at the loop coil selected by the
above-mentioned selecting circuit 204X or 204Y is supplied through
a common amplifier 251 to a bandpass filter (BPF) 252 which passes
the above-mentioned specific frequency f0, and a signal passed
through the bandpass filter 252 is supplied to a detector 253.
Further, a signal detected by the detector 253 is supplied through
a sample-and-hold (S/H) circuit 254 to an analog-to-digital (A/D)
converter 255, and a signal, which was converted from an analog
signal to a digital signal by the A/D converter 255, is inputted to
the control circuit 205. As a result, the control circuit 205 can
recognize magnitude of a received signal and the position of the
loop coil which receives a signal.
[0230] Therefore, according to the arrangement shown in FIG. 27,
the control circuit 205 can detect the position at which the
position pointing pen 239 is moved close to the sensor coil group
201 and can function as the position detecting apparatus. Also, if
the control circuit 205 is provided as a central processing unit
(CPU) for carrying out processing based on an arbitrary program,
then the position detecting apparatus can constitute part of a
computer system for carrying out processing for detecting the
position at which the position pointing pen 239 approaches the
sensor coil group 201. In this case, if the resonance circuits
built into the position pointing pens 239 are operated one at a
time under the control of the control circuit 205, then power
consumption can be decreased and the life of the built-in battery
can be prolonged.
[0231] As described above, the position pointing device of several
of the above-described embodiments of the present invention
includes a built-in power supply unit for transmitting a signal to
point at least the position to a position detecting tablet. This
position pointing device includes signal transmitting units
provided at a plurality of portions of the position pointing device
and a control unit for controlling a plurality of signal
transmitting units such that the units are in an energized or
de-energized state. Consequently, power consumption in the position
pointing device can be decreased and life of the built-in battery
can be prolonged.
[0232] Also, according to the position pointing device of several
of the above-described embodiments of the present invention, a
built-in power supply unit transmits a signal to point at least the
position of the position pointing device to a position detecting
tablet. This position pointing device includes signal transmitting
units provided at a plurality of portions of the position pointing
device and a power control unit for controlling transmission power
of a plurality of signal transmitting units at least in two levels.
Consequently, power consumption in the position pointing device can
be decreased and life of the built-in battery can be prolonged.
[0233] Further, according to the position detecting apparatus of
several of the above-described embodiments of the present
invention, the position input system includes a position pointing
device having a built-in power supply unit to transmit a signal to
provide positioning information to a position detecting tablet, a
plurality of signal transmitting units provided at a plurality of
portions, and a power control unit for controlling transmission
power to a plurality of signal transmitting units. The position
detecting tablet includes a discriminating unit for discriminating
signals from the plurality of signal transmitting units, and the
position detecting apparatus outputs information based on the
positioning information from the position pointing device and
discrimination information from the discriminating unit. Thus,
power consumption in the position pointing device can be decreased
and life of the built-in battery can be prolonged.
[0234] Furthermore, according to several of the above-described
embodiments of the present invention, a computer system is provided
which includes a position pointing device having a built-in power
supply unit to transmit a signal identifying at least the position
of the position pointing device relative to a position detecting
tablet, signal transmitting units provided at a plurality of
portions, a power control unit for controlling transmission power
to a plurality of signal transmitting units, the position detecting
tablet, and a computer. The position detecting tablet includes a
discriminating unit for discriminating each of signals from a
plurality of signal transmitting units and the computer executes
processing corresponding to positioning information from the
position pointing device and based on discrimination information
from the discriminating unit.
[0235] It should be noted that the present invention is not limited
to the above-described embodiments. Also, the two
functions--pen-point function (writing of information) and the
eraser function (erasing of written information) of this position
pointing device--are compatible with written information of
different colors and of different thickness. Furthermore, the
position pointing device according to the various embodiments of
the present invention can include two, three, or more than three
functions, with each "side" operated alternately so that only one
side is powered at an operational level at a time, and so that the
other side(s) is either not powered or operated at a decreased
power.
[0236] It should be understood by those skilled in the art that
various modifications, combinations, sub-combinations and
alterations may occur depending on design requirements and other
factors, insofar as they are within the scope of the appended
claims or the equivalents thereof.
* * * * *