U.S. patent application number 10/943460 was filed with the patent office on 2005-02-24 for dental apparatus.
This patent application is currently assigned to J. Morita Manufacturing Corporation. Invention is credited to Katsuda, Naoki, Matoba, Kazunari, Nakai, Teruji.
Application Number | 20050042572 10/943460 |
Document ID | / |
Family ID | 26614634 |
Filed Date | 2005-02-24 |
United States Patent
Application |
20050042572 |
Kind Code |
A1 |
Katsuda, Naoki ; et
al. |
February 24, 2005 |
Dental apparatus
Abstract
A dental equipment for cutting teeth, forming root canals and so
on. The dental apparatus includes: an actuator for actuating a
cutting tool; a load sensor for sensing a load worked in the
cutting tool; and a load indicator for making an operator know the
load sensed by the load sensor visually, aurally and/or
tactily.
Inventors: |
Katsuda, Naoki; (Kyoto,
JP) ; Matoba, Kazunari; (Kyoto, JP) ; Nakai,
Teruji; (Kyoto, JP) |
Correspondence
Address: |
KODA & ANDROLIA
2029 CENTURY PARK EAST
SUITE 1430
LOS ANGELES
CA
90067-3024
US
|
Assignee: |
J. Morita Manufacturing
Corporation
|
Family ID: |
26614634 |
Appl. No.: |
10/943460 |
Filed: |
September 17, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10943460 |
Sep 17, 2004 |
|
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|
10134218 |
Apr 29, 2002 |
|
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Current U.S.
Class: |
433/98 ;
433/102 |
Current CPC
Class: |
A61C 19/042 20130101;
A61C 1/0015 20130101; A61C 1/186 20130101; A61C 19/041 20130101;
A61C 3/00 20130101 |
Class at
Publication: |
433/098 ;
433/102 |
International
Class: |
A61C 001/02; A61C
005/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 2, 2001 |
JP |
2001-135129 |
Apr 26, 2002 |
JP |
2002-126446 |
Claims
1-26. (canceled).
27: A dental apparatus comprising: a driving device for driving a
cutting tool; a root canal length measuring device for measuring a
root canal length; and a control device for controlling the driving
device so that a driving force of the cutting tool changes
depending on a measurement value of the root canal length measured
by the root canal length measuring device, wherein the control
device controls `the driving device to perform one of stopping a
rotation of the cutting tool; reversing the rotation thereof;
decreasing a speed of the rotation thereof; and repeating forward
and backward rotations thereof.
28: The dental apparatus as claimed in claim 27, wherein the
control device includes a rotation control device for controlling
the driving device so that the rotation of the cutting tool changes
depending on the measurement value of the root canal length
measured by the root canal length measuring device.
29: The dental apparatus as claimed in claim 28, wherein the
rotation control device controls the driving device so that the
rotation speed of the cutting tool changes from a reference
rotation speed to a preset rotation speed depending on the
measurement value of the root canal length measured by the root
canal length measuring device.
30: The dental apparatus as claimed in claim 28, wherein the
rotation control device controls the driving device so that the
rotation speed of the cutting tool changes from a reference
rotation speed at a preset reduction rate depending on the
measurement value of the root canal length measured by the root
canal length measuring device.
31: The dental apparatus as claimed in claim 29, further comprising
a setting device for setting the reference rotation speed and the
preset rotation speed.
32: The dental apparatus as claimed in claim 30, further comprising
a setting device for setting the reference rotation speed and the
reduction rate
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon application No. 2001-135129
filed in Japan, the contents of which are hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a dental apparatus. More
particularly, it relates to the dental apparatus capable of cutting
teeth, forming root canals and applying to dental implant, for
example, by driving a cutting tool.
[0004] 2. Description of the Related Arts
[0005] Conventionally, a dental apparatus wherein the rotation of
its cutting tool (file) is controlled depending on the load torque
applied to the cutting tool to prevent the breakage of the cutting
tool when expanding a root canal, for example, has been proposed.
In this dental apparatus, the cutting tool rotates reversibly or
stops when the load torque reaches a reference torque or more (for
example, Japanese Non-examined Patent Publication No. Hei
9-38108).
[0006] If a root canal is bent for example, however, the load
increases spontaneously even when the operator has no intention of
increasing the load, and the rotation of the cutting tool stops or
reverses unexpectedly. Hence, the operator is required to carry out
cutting while being fully careful so that the load torque does not
reach a reference load torque. However, the smaller the load, the
lower the efficiency of the cutting. On the other hand, if the load
is increased so as to be nearly equal to the reference load torque,
the cutting tool stops or reverses frequently, thereby lowering the
efficiency of the cutting in some cases. In other words, it was
impossible to carry out the cutting at an appropriate load not
exceeding the reference load efficiently without worries.
[0007] Furthermore, the operator is required to carry out the
cutting while simultaneously checking the measurement result of a
root canal length and the torque. In the conventional dental
apparatus, these values were not displayed so as to be checked
simultaneously, whereby the efficiency of the cutting was low.
SUMMARY OF THE INVENTION
[0008] Accordingly, it is an object of the present invention to
provide a dental apparatus capable of carrying out cutting
efficiently without worries.
[0009] In order to achieve the above object, according to one
aspect of the present invention, there is provided a dental
apparatus comprising: a driving device for driving a cutting tool;
a load detector for detecting a load applied to the cutting tool;
and a load information device for informing an operator of the load
detected by the load detector by means of at least one of view
(sight), sound and vibration.
[0010] In the above-mentioned configuration, in the case when the
driving device such as a motor rotates the cutting tool, the load
detector detects a drive torque produced when the driving device
rotates the cutting tool as a load. In the case when the driving
device such as that used for a scaler vibrates the cutting tool in
its axial direction, the load detector detects a braking force
required to stop the vibration as a load. In the case of the
rotation of the motor, the load may be detected directly from the
cutting tool itself by using a strain gauge attached to the cutting
tool.
[0011] With the above-mentioned configuration, the operator can
check the load applied to the cutting tool by using the load
information device, visually, aurally and/or tactily.
[0012] Hence, the operator can carry out cutting efficiently
without worries.
[0013] Preferably, the dental apparatus is provided with reference
load information device for informing the operator of a reference
load by means of at least one of view, sound and vibration.
[0014] With the above-mentioned configuration, the operator can
check the difference (margin) between the load applied to the
cutting tool and the reference load, visually, aurally and/or
tactily. Hence, the operator can easily make an adjustment so that
an appropriate load applies to the cutting tool. This makes the
dental apparatus convenient.
[0015] Further, preferably, the dental apparatus further comprises
provided with a reference load setting device for setting the
above-mentioned reference load.
[0016] With the above-mentioned configuration, the operator can set
the reference load as desired. This makes the dental apparatus easy
to use.
[0017] Preferably, the dental apparatus further comprises a control
device for controlling the driving device so that the load applied
to the cutting tool decreases when the load detected by the load
detector exceeds the reference load.
[0018] In the above-mentioned configuration, when the detected load
exceeds the reference load, the control device controls the driving
device and appropriately changes its drive state, for example,
stops the cutting tool, rotates the cutting tool backward,
decreases the rotation speed of the cutting tool or repeat the
forward and backward rotation of the cutting tool. Hence, the load
applied to the cutting tool can be decreased.
[0019] With the above-mentioned configuration, the load applied to
the cutting tool is prevented from exceeding the reference load,
thereby preventing the breakage of the cutting tool.
[0020] Preferably, the load information device is provided with
plural segments for indicating the load detected by the load
detector, said segments being arranged in correspondence with a
value of the load. The reference load information device selects
and displays at least one of the segments of the load information
device or at least one of the other segments disposed near the
segments of the load information device in order to indicate the
reference load in accordance with substantially the same
relationship as the relationship between the position of the
segments of the load information device and the load. Load
indicating state in which the load information device indicates the
load differs from reference load indicating state in which the
reference load information device indicates the reference load.
[0021] In the above-mentioned configuration, the load displayed by
the load information device and the reference load displayed by the
reference load information device are based on the same standard.
At this time, the displaying method for the load displayed by the
load information device differs from the displaying method for the
reference load information device. The two can be distinguished
easily, and the inequality relationship between the two can be
recognized easily. For example, the load and the reference load are
displayed by flashing display dots or by changing the colors
thereof.
[0022] The load information device may display the load detected by
the load detector immediately or at constant intervals (for
example, every second).
[0023] Preferably, the load information device displays for a
constant period a maximum value of the load detected by the load
detector within a predetermined period.
[0024] With the above-mentioned configuration, the load information
device has a peak-hold function to prevent the display from
changing frequently. For this reason, the display of the load is
easy to see.
[0025] Preferably, the load information device changes load
indicating state in which the load information device indicates the
load detected by the load detector, when the load detected by the
load detector exceeds a second reference load smaller than a first
reference load.
[0026] With the above-mentioned configuration, when the load
detected by the load detector exceeds the second reference load and
approaches the first reference load, the load information device
changes the state of displaying the load by flashing display dots
or by changing the colors thereof. It is thus possible to call the
attention of the operator to the display visually.
[0027] Preferably, the dental apparatus further comprises a sound
alarm for giving a sound when the load detected by the load
detector exceeds a second reference load smaller than a first
reference load.
[0028] With the above-mentioned configuration, when the load
detected by the load detector exceeds the second reference load and
approaches the first reference load, the sound alarm generates a
sound, such as a chime sound and a buzzer sound. It is thus
possible to call the attention of the operator to the display
audibly.
[0029] Preferably, the dental apparatus further comprises a
rotation speed control device for controlling the driving device to
gradually decrease a rotation speed of the cutting tool when the
load detected by the load detector approaches a reference load.
[0030] If the rotation speed decreases after the load exceeded the
reference load just as in the case of the conventional device, the
load exceeding the reference load is applied to the cutting tool.
In the case of the above-mentioned configuration, however, when the
load approaches the reference load, the rotation speed of the
cutting tool decreases, and the load applied to the cutting tool is
reduced. It is thus possible to prevent a load larger than the
reference load from applying to the cutting tool. Hence, it is
possible to prevent the breakage of the cutting tool more
securely.
[0031] Preferably, the load information device is provided with
plural segments arranged in one direction in correspondence with
value of the load so that the positions of displayed segments among
the plural segments indicate the load detected by the load
detector.
[0032] With the above-mentioned configuration, the plural segments
are disposed in a line or a curve, just like a bar graph or a
meter, for example. The load can be displayed intuitively in
accordance with the positions of the segments that are lit.
[0033] Preferably, the dental apparatus further comprises at least
one of a visual direction indicator for indicating driven direction
of the cutting tool visually and of an audible direction indicator
for indicating driven direction of the cutting tool audibly.
[0034] With the above-mentioned configuration, when the driving
device rotates the cutting tool, and when the load of the cutting
tool increases and the cutting tool reverses automatically, the
operator can recognize the rotation direction of the cutting tool
visually or audibly. Hence, the operator can carry out operation
smoothly. Furthermore, when the driving device advances or-
retracts the cutting tool, the operator can also carry out
operation smoothly.
[0035] The driving direction of the cutting tool may be displayed
(or notified by a sound) at all times or displayed (or notified by
a sound) only when the driving direction is changed. In the later
case, the driving direction may be displayed (or notified by a
sound) only for an appropriate period after the change of the
driving direction.
[0036] Preferably, the load information device is provided with a
display portion placed on a handpiece in which the driving device
and the load detector are disposed.
[0037] With the above-mentioned configuration, the cutting tool
driven by the driving device is provided in the handpiece. When the
operator looks away from the cutting tool and looks at the display
portion during cutting operation, the movement of the line of sight
is limited in a short distance. Hence, the operator can easily look
at the display portion. The dental apparatus can thus be easy to
use.
[0038] The handpiece may be connected to the controller of the
dental apparatus via a tube. Instead of this configuration, a
cordless handpiece provided with the driving device, the load
detector and the load information device and including a battery
might also be used. In this case, the operator can hold and use the
handpiece without restraint. The dental apparatus can thus be used
conveniently.
[0039] Preferably, the dental apparatus further comprises a root
canal length measuring device and plural segments arranged
two-dimensionally in a first direction and in a second direction
nearly perpendicular to the first direction. The load information
device indicates the root canal length measured by the root canal
length measuring device in accordance with the positions of at
least one of displayed segments among the plural segments arranged
in the first direction. The load information device indicates the
load detected by the load detector in accordance with the width of
displayed segments among the plural segments arranged in the second
direction.
[0040] With the above-mentioned configuration, the root canal
length measured by the root canal length measuring device and the
load detected by the load detector are displayed simultaneously at
one area so as to be related to each other. Hence, the operator can
recognize them easily.
[0041] The cutting tool may be used as an electrode for the root
canal length measurement.
[0042] Furthermore, according to another aspect of the present
invention, there is provided a dental apparatus configured as
described below.
[0043] The dental apparatus comprises a driving device for driving
a cutting tool; a root canal length measuring device for measuring
a root canal length; and a control device for controlling the
driving device so that a driving force of the cutting tool changes
depending on a measurement value of the root canal length measured
by the root canal length measuring device.
[0044] In the above-mentioned configuration, when the driving
device, such as a motor, rotates the cutting tool, the control
device controls the rotation speed, rotation direction, driving
torque, etc. of the cutting tool driven by the driving device. In
the case when the driving device such as that used for a scaler
vibrates the cutting tool, the control device controls vibration
amplitude, vibration cycle, vibration waveform, vibration
generating force (or braking force required to stop vibration),
etc.
[0045] With the above-mentioned configuration, the cutting tool can
be driven in optimum conditions depending on the position of the
cutting tool in the direction of the root canal length.
[0046] The cutting tool may be used as an electrode for measuring
the root canal length.
[0047] Preferably, the control device includes a rotation control
device for controlling the driving device so that the rotation of
the cutting tool changes depending on the measurement value of the
root canal length measured by the root canal length measuring
device.
[0048] With the above-mentioned configuration, cutting can be
carried out while changing the rotation speed and direction of the
cutting tool depending on the distance to the apex and while
carefully advancing the cutting tool little by little when the
cutting tool approaches the apex, for example.
[0049] Preferably, the rotation control device controls the driving
device so that the rotation speed of the cutting tool changes from
a reference rotation speed to a preset rotation speed depending on
the measurement value of the root canal length measured by the root
canal length measuring device.
[0050] With the above-mentioned configuration, cutting can be
carried out efficiently at the reference rotation speed until the
cutting tool approaches the apex. When the cutting tool approaches
the apex, the rotation speed is changed so that cutting can be
carried out carefully.
[0051] Preferably, the rotation control device controls the driving
device so that the rotation speed of the cutting tool changes from
a reference rotation speed at a preset reduction rate depending on
the measurement value of the root canal length measured by the root
canal length measuring device.
[0052] With the above-mentioned configuration, by setting the
reference rotation speed, the rotation speed of the cutting tool
near the apex can be set eventually. The reduction rate may change
stepwise or continuously depending on the measurement value of the
root canal length.
[0053] Preferably, the dental apparatus further comprises a setting
device for setting the reference rotation speed and the preset
rotation speed.
[0054] With the above-mentioned configuration, the driving
conditions of the cutting tool can be set and changed as desired.
The dental apparatus can thus be used conveniently.
[0055] Furthermore, according to still another aspect of the
present invention, there is provided a dental apparatus configured
as described below.
[0056] The dental apparatus comprises a driving device for rotating
a cutting tool; a load torque detector for detecting a load torque
applied to the cutting tool; and a control device for performing
one of stooping a rotation of the cutting tool; reversing a
direction of the rotation; decreasing a speed of the rotation; and
repeating a forward rotation thereof and a backward rotation
thereof, when the load torque detected by the load torque detector
exceeds a first reference load, and for controlling the driving
device to perform one of increasing the speed of the
rotation;-rotating the cutting tool forward; and vibrating the
cutting tool by applying a predetermined force, when the load
torque detected by the load torque detector reaches a second
reference load smaller than the first reference load.
[0057] With the above-mentioned configuration, when the load
applied to the cutting tool exceeds the first reference load, the
load is decreased. When the load applied to the cutting tool is
smaller than the second reference load, the load is increased.
Hence, the load can be set at a value between the first and second
reference loads.
[0058] Furthermore, according to still another aspect of the
present invention, there is provided a dental apparatus configured
as described below.
[0059] The dental apparatus comprises a driving device for driving
a cutting tool; a load detector for detecting a load applied to the
cutting tool; a load information device for informing an operator
of the load detected by the load detector by means of at least one
of view, sound and vibration; a root canal length measuring device
for measuring a root canal length by using the cutting tool; and a
root canal length information device for informing the operator of
the root canal length detected by the root canal length measuring
device by means of at least one of view, sound and vibration,
wherein the load and the root canal length are informed
simultaneously by the load information device and the root canal
length information device.
[0060] With the above-mentioned configuration, the operator can
carry out operation while simultaneously checking the measurement
result of the root canal length and the load applied to the cutting
tool, visually, aurally and/or tactily. The operator can thus work
efficiently.
BRIEF DESCRIPTION OF THE DRAWINGS
[0061] This and other objects and features of the present invention
will become clear from the following description taken in
conjunction with the preferred embodiment thereof with reference to
the accompanying drawings.
[0062] FIG. 1 is a circuit diagram of a dental apparatus in
accordance with an embodiment of the present invention.
[0063] FIG. 2 is an external view showing the dental apparatus
shown in FIG. 1.
[0064] FIG. 3 is a plan view showing a LCD panel on a display
portion of the dental apparatus shown in FIG. 1.
[0065] FIGS. 4A, 4B and 4C are views illustrating examples of
display as displayed on the LCD panel.
[0066] FIG. 5 is a view illustrating another example of display as
displayed on the LCD panel.
[0067] FIG. 6 is a view illustrating still another example of
display as displayed on the LCD panel.
[0068] FIG. 7 is a view illustrating a further example of display
as displayed on the LCD panel.
[0069] FIG. 8 is an example of a flowchart for the control of the
dental apparatus.
[0070] FIG. 9 is another example of a flowchart for the control of
the dental apparatus.
[0071] FIG. 10 is still another example of a flowchart for the
control of the dental apparatus.
[0072] FIG. 11 is a still further example of a flowchart for the
control of the dental apparatus.
[0073] FIG. 12 is an example showing an operation of a sound alarm
provided with the dental apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0074] Before the description of the preferred embodiment according
to the present invention proceeds, it is to be noted that like or
corresponding parts are designated by like reference numerals
throughout the accompanying drawings.
[0075] A dental apparatus in accordance with the embodiment of the
present invention will be described below referring to FIGS. 1 to
10.
[0076] FIG. 1 is a circuit diagram of a dental apparatus in
accordance with a preferred embodiment of the present invention.
Reference numeral 1 designates a CPU for controlling the overall
operation of the dental apparatus. Reference numeral 2 designates a
motor for driving a cutting tool 17. Reference numeral 3 designates
a transistor switch. Reference numeral 4 designates a driver
circuit for driving the transistor switch. Reference numeral 5
designates a rotation direction selection switch. Reference numeral
6 designates a resistor for detecting a load torque. Reference
numeral 7 designates a root canal length measurement circuit.
Reference numeral 8 designates a display device. Reference numeral
11 designates a variable resistor for setting a reference load
torque. Reference numeral 12 designates a variable resistor for
setting a duty ratio. Reference numeral 13 designates a variable
resistor for setting a reference position. Reference numeral 14
designates a battery. Reference numeral 15 designates a main
switch. Reference numeral 17 designates the cutting tool. These are
connected to the CPU 1 as shown in the figure.
[0077] The driver circuit 4 is activated by a control signal output
from the terminal 4a of the CPU 1 and turns ON/OFF the transistor
switch 3. The CPU 1 outputs a control signal that is a pulse signal
having a constant cycle and a duty ratio depending on the setting
of the variable resistor 12. The motor 2 rotates depending on the
output corresponding to the duty ratio.
[0078] The CPU 1 measures the voltage at the terminal 6a of the
resistor 6 to detect the load torque of the motor 2. Furthermore,
the voltage at the terminal 5a of the CPU 1 is changed to Lo/Hi,
whereby the rotation direction selection switch 5 is activated and
the motor 2 can be rotated forward and backward. The CPU 1 detects
the reference load torque, duty ratio and reference position preset
by the variable resistors 11, 12 and 13.
[0079] FIG. 2 is an external view showing a cordless dental
apparatus 21 comprising the components of the circuit shown in FIG.
1. In this embodiment, a dental handpiece 23 is shown. At the tip
of the head 22 of the dental handpiece 23, a root canal forming
file (hereafter referred to as the file 17) is mounted as the
cutting tool 17. The file 17 is electrically connected to the
measurement terminal of the root canal length measurement circuit 7
via a conductive member inside the handpiece 23 so as to be used as
an electrode for root canal length measurement. A grounding
electrode 18 is electrically connected to the grounding terminal of
the root canal length measurement circuit 7 via a lead wire 18a.
Reference numeral 11a designates a reference load torque setting
device. Reference numeral 12a designates a rotation speed setting
device. Reference numeral 13a designates a reference position
setting device for controlling the driving device for the cutting
tool depending on the output of the root canal length measurement
circuit 7. In this embodiment, the reference load torque setting
device 11a, the rotation speed setting device 12a and the reference
position setting device 13a are mounted on the handpiece 23.
However, in a configuration wherein a separate controller is
connected to the handpiece 23 via a cord, the setting device 11a,
12a and 13a may be mounted on the separate controller.
[0080] FIG. 3 shows an example of a LCD (Liquid Crystal Display)
panel 50 mounted on the display device 8.
[0081] The LCD panel 50 comprises a dot display portion 52
including numerous segments for minutely displaying a measured root
canal length, a zone display portion 54 for displaying the measured
root canal length stepwise in divided zones, a boundary display
portion 56 for displaying the boundaries of the zones and an
attainment rate display portion 58 for displaying the rate of
attainment to an apex. As the measured root canal length increases,
the segments are lit sequentially downward.
[0082] Furthermore, the LCD panel 50 is provided with a dot display
portion 60 including numerous segments for displaying a measured
load torque and a zone display portion 62 for displaying the load
torque stepwise in divided zones. As the measured load torque
increases, the segments are lit sequentially downward.
[0083] For example, the diagonally shaded segments 60a of the dot
display portion 60 are lit depending on the measured load torque. A
peak-hold function is provided to prevent the display from changing
frequently. In other words, the maximum of the load torque measured
within a predetermined time is displayed for a constant time.
[0084] Among the segments of the dot display portion 60, a segment
60b corresponding to the reference load torque that is preset by
using the variable resistor 11 is also lit. Hence, the margin
between the measured load torque and the reference load torque can
be recognized at a glance.
[0085] In addition, numeral 64 designates a numeric value display
portion for displaying the numeric values of rotation speed and
load. Reference numeral 68 designates a rotation display portion
for displaying the direction of rotation and the slow/rapid
distinction of rotation speed.
[0086] The measured load torque and the preset reference load
torque can be displayed in various ways as described below.
[0087] Alternatively, for example, when segments arranged
one-dimensionally are used, display can be carried out as shown in
the schematic views of FIGS. 4A, 4B and 4C.
[0088] In an example 100 of display shown in FIG. 4A, segments 102
are lit in green sequentially downward depending on the measured
load torque. A segment 106 corresponding to the preset reference
load torque is lit in red. The other segments 104 and 108 are not
lit.
[0089] In an example 110 of display shown in FIG. 4B, segments 112
are lit in green sequentially downward depending on the measured
load torque. Segments 116 for displaying a torque larger than the
preset reference load torque are lit so as to flash in red. The
other segments 114 are not lit.
[0090] In an example 120 of display shown in FIG. 4C, segments are
divided into three zones and lit in three colors depending on the
preset reference load torque. For example, segments 122 for
displaying torques sufficiently smaller than the preset reference
load torque are lit in green. Segments 124 for displaying torques
close to the preset reference load torque is lit in yellow.
Segments 126 for displaying torques larger than the preset
reference load torque are lit in red. In addition, a segment 122a
corresponding to the preset reference load torque flashes.
[0091] FIG. 5 shows an example 200 of display wherein plural
segments 210 are arranged two-dimensionally to display the result
of root canal length measurement, as well as a measured load torque
and the preset reference load torque.
[0092] Segments 210 are arranged in matrix on a LCD panel between
display portions 202 and 204 that schematically indicate a tooth.
As the formation of a root canal advances and as the length of the
root canal becomes larger and the end of the root canal approaches
the apex, lower segments are lit. The larger the load torque, the
wider the segments horizontally arranged from each of the center
column segments 212 are lit in the horizontal direction. For
example, diagonally shaded segments 215 are lit in green. The
vertical position of the segments 215 indicates the distance
between the end of the root canal and the apex. Furthermore, the
horizontal length (width) of the segments 215 corresponds to the
measured load torque. In the same row as that of the segments 215,
two diagonally shaded segments 216a and 216b are lit in red. From
the segments 216a and 216b, segments are disposed linearly in the
vertical direction. The distance between the two segments 216a and
216b indicates the preset reference load torque. The distance from
the segments 215 to the segments 216a and 216b indicates a margin
to the reference load torque.
[0093] In this example, the remaining distance to the apex and the
difference between an actual load torque and the reference load
torque are displayed on a single display area, thereby enhancing
convenience.
[0094] Furthermore, in this example, the change of the load torque
with respect to the root canal length is stored sequentially and
displayed continuously. However, instead of storing the change
sequentially and displaying it continuously, only the current root
canal length and the load torque corresponding thereto may be
displayed in real time. In addition, instead of the segments 216a
and 216b, printed continuous solid lines may be used.
[0095] FIG. 6 shows another example 300 of display for displaying
the result of root canal length measurement and load torque.
[0096] The root canal length is displayed by an analog indication
needle 304 rotating around a shaft 302. Reference numeral 306
designates a scale for the indication needle 304. The load torque
is displayed by segments 310 arranged below the scale 306. As the
segments 310 are lit wider in a clockwise direction, a larger load
value is displayed. Among the segments 310, only the segments 312a
corresponding to the detected load torque are lit. The segments 310
may be divided in colors depending on the reference load torque.
For example, segments 312 for displaying torques sufficiently
smaller than the preset reference load torque are lit in green.
Segments 314 for displaying torques close to the preset reference
load torque are lit in yellow. Segments 316 for displaying torques
larger than the preset reference load torque are lit in red.
[0097] FIG. 7 shows another example 400 of display for displaying
the result of root canal length measurement and the load torque.
The root canal length is displayed by an analog indication needle
304 rotating around a shaft 302. Reference numeral 306 designates a
scale for the indication needle 304. The load torque is displayed
by a scale 310 disposed below the scale 306. As an analog
indication needle 313 moves in a clockwise direction, a larger load
value is displayed. The load torque obtained at a specific root
canal length is displayed by the analog indication needle 313 and
the scale 310. As described above, the result of the root canal
length measurement and the load torque are displayed
simultaneously. Hence, the operator can carry out treatment while
checking situations wherein the cutting tool is approaching the
apex and the torque is changing. For this reason, the root canal
can be expanded smoothly without damaging the cutting tool. In
addition, these two display means can be mounted on a cordless
handpiece.
[0098] Next, the control of the dental apparatus 21 will be
described below referring to FIGS. 8 to 10.
[0099] FIG. 8 is a flowchart for the control of the dental
apparatus 21 depending on the result of root canal length
measurement. The CPU 1 repeatedly carries out the control flow
shown in the figure at appropriate timing.
[0100] First, the CPU 1 determines whether root canal length
measurement is possible or not (at step #10). When the measurement
is impossible (NO at step #10), the CPU 1 stops the motor 2 (at
step #20). When the measurement is possible (YES at step #10), the
CPU 1 determines whether the end of the root canal has reached a
position up to 4 mm to the apex or not (at step #12). Until the end
of the root canal reaches the position up to 4 mm to the apex (NO
at step #12), the CPU 1 drives the motor 2 so that the file 17
rotates at 1000 rpm (at step #19).
[0101] When the end of the root canal reaches the position up to 4
mm to the apex (YES at step #14), the CPU 1 determines whether the
end of the root canal has reached a position up to 1.5 mm to the
apex or not (at step #14). Until the end of the root canal reaches
the position up to 1.5 mm to the apex (NO at step #14), the CPU 1
drives the motor 2 so that the file 17 rotates at 400 rpm (at step
#18).
[0102] When the end of the root canal reaches the position up to
1.5 mm to the apex (YES at step #14), the CPU 1 drives the motor 2
so that the file 17 rotates at 150 rpm (at step #16).
[0103] By the control shown in FIG. 8, the motor speed is
automatically set at the high speed so that the cutting tool can
carry out efficient cutting at the upper portion of the root canal.
When the end of the root canal approaches the apex, the motor speed
is automatically changed to the low speed to prevent the breakage
of the file 17. Hence, the operator is not required to change the
setting of the rotation speed depending on the position of the end
of the root canal, whereby the operation can be carried out
efficiently and conveniently.
[0104] The preset distances (4 mm and 1.5 mm) up to the apex in
FIG. 8 and the rotation speeds (1000 rpm, 400 rpm and 150 rpm) of
the motor 2 may be changed as desired by the operator. In addition,
the rotation speed of the motor 2 may be changed continuously.
[0105] Furthermore, intermediate rotation speeds may be set by
multiplying the initial rotation speed (maximum speed) of the motor
2 by preset coefficients.
[0106] FIG. 9 is another flowchart for the control of the dental
apparatus 21 depending on the result of the root canal length
measurement. The CPU 1 repeatedly carries out the control flow
shown in the figure at appropriate timing.
[0107] First, the CPU 1 determines whether root canal length
measurement is possible or not (at step #30). When the measurement
is impossible (NO at step #30), the CPU 1 stops the motor 2 (at
step #44). When the measurement is possible (YES at step #30), the
CPU 1 determines whether the end of the root canal has reached a
position up to 5 mm to the apex or not (at step #32). Until the end
of the root canal reaches the position up to 5 mm to the apex (NO
at step #32), the motor 2 rotates forward (at step #44).
[0108] When the end of the root canal reaches the position up to 5
mm to the apex (YES at step #32), the CPU 1 determines whether the
end of the root canal has reached a position up to 3 mm to the apex
or not (at step #34). Until the end of the root canal reaches the
position up to 3 mm to the apex (NO at step #34), the motor 2
rotates 15 degrees backward and 90 degrees forward repeatedly (at
step #42).
[0109] When the end of the root canal reaches the position up to 3
mm to the apex (YES at step #34), the CPU 1 determines whether the
end of the root canal has reached a position up to 2 mm to the apex
or not (at step #36). Until the end of the root canal reaches the
position up to 2 mm to the apex (NO at step #36), the motor 2
rotates 30 degrees backward and 90 degrees forward repeatedly (at
step #40).
[0110] When the end of the root canal reaches the position up to 2
mm to the apex (YES at step #36), the motor 2 rotates 90 degrees
backward and 90 degrees forward repeatedly (at step #38).
[0111] By the control shown in FIG. 9, when the end of the root
canal reaches the apex, the motor 2 rotates backward and forward
repeatedly, whereby it is possible to prevent the breakage of the
file 17.
[0112] FIG. 10 is a flowchart for the control of the dental
apparatus 21 depending on the result of load torque measurement.
The CPU 1 repeatedly carries out the control flow shown in the
figure at appropriate timing.
[0113] First, the CPU 1 compares the measurement value of the load
torque with a preset reference load torque (referred to as "first
reference" in FIG. 10)(at step #50). When the measurement value of
the load torque is larger than the reference load torque (YES at
step #50), the CPU 1 stops the rotation of the motor 2 (at step
#56). Instead of stopping the rotation of the motor 2 at step #56,
the motor 2 may be rotated backward.
[0114] When the measurement value of the load torque is not larger
than the reference load torque (NO at step #50), the measurement
value of the load torque is compared with a value (referred to as
"second reference "in FIG. 10) that is smaller than the reference
load torque by a predetermined value (at step #52). When the
measurement value of the load torque is smaller than the second
reference (YES at step #52), the rotation speed of the motor 2 is
increased (at step #54).
[0115] Hence, the load torque is controlled so as to be set at a
value between the first reference and the second reference. The
cutting can thus be carried out efficiently while preventing the
breakage of the file 17.
[0116] FIG. 11 is another flowchart for the control of the dental
apparatus 21 depending on the result of load torque measurement.
The CPU 1 repeatedly carries out the control flow shown in the
figure at appropriate timing.
[0117] First, the CPU 1 compares the measurement value of the load
torque with a preset reference load torque (at step #60). When the
measurement value of the load torque is larger than the reference
load torque (YES at step #60), the CPU 1 stops the rotation of the
motor 2 (at step #66). Instead of stopping the rotation of the
motor 2 at step #66, the motor 2 may be rotated backward.
[0118] When the measurement value of the load torque is not larger
than the reference load torque (NO at step #60), the difference
(hereafter referred to as "torque difference") between the
measurement value of the load torque and the reference load torque
is obtained (at step #62). The motor 2 is rotated at a rotation
speed proportional to the torque difference (at step #64).
[0119] In other words, the rotation speed N of the motor 2 is
represented by the following equation (1).
N=.alpha.{N.sub.0.times.(T.sub.0-T)/T.sub.0} (1)
[0120] wherein T.sub.0 is the reference load torque, T is the
measurement value of the load torque, N0 is the maximum speed (1000
rpm for example) of the motor 2, and .alpha. is a constant.
Although the constant a is generally a fixed value, it may be
varied.
[0121] Hence, as the measurement value T of the load torque
approaches the preset reference load torque TO, the rotation speed
N of the motor 2 decreases gradually.
[0122] As described above, the measurement result of the root canal
length and the torque are displayed simultaneously during the
operation of the dental apparatus. The operator can thus carry out
cutting efficiently without worries while checking the displayed
values.
[0123] Although the present invention has been fully described in
connection with the preferred embodiment thereof with reference to
the accompanying drawings, it is to be noted that various changes
and modifications are also apparent to those skilled in the
art.
[0124] For example, instead of using the display device 8, or
combining with the display device 8, a sound alarm, which changes
the sound depending on detected load and/or measured root canal
length, may be used.
[0125] FIG. 12 shows an embodiment schematically. A sound alarm
generates two types of sound, one of which informs an operator of
the root canal length information, another of which informs the
operator of the load information. Reference numeral 500 designates
a crown of a tooth. Reference numeral 504 designates an apex of the
tooth. Reference numeral 502 designates a reference position short
of the apex 504 by a distance, which can be set and changed as
desired.
[0126] As for the root canel information, one type of sound
generated by the sound alarm is relatively high, until the end of
the root canel reaches the reference position 502, or when the tip
17a of a cutting tool 17 is placed in a section as shown by
reference numeral 510. After reaching the reference position 502,
or when the tip 17a is placed in a section as shown by reference
numeral 512, one type of sound becomes relatively low.
[0127] As for the load information, another type of sound generated
by the sound alarm stops until detected load torque exceeds a first
reference value 522, or when detected load torque is placed in a
section as shown by reference numeral 530. After detected load
torque exceeds the first reference value 522 and until detected
load torque exceeds a second reference value 524 smaller than the
first reference value 522, or when detected load torque is placed
in a section as shown by reference numeral 532, another type of
sound sounds interruptedly. After detected load torque exceeds the
second reference value 524, or when detected load torque is placed
in a section as shown by reference numeral 534, another type of
sound sounds continuously. The first reference value 522 and the
second reference value 524 can be set and changed as desired.
[0128] In addition, depending on measured root canel length and/or
detected load torque, the cutting tool 17 may be driven. For
example, when the end of the root canel (the tip 17a of the cutting
tool 17) reaches the reference point 502, and/or when detected load
torque is placed in the section 532 and/or the section 534, it is
possible to be controlled so as to perform stopping the cutting
tool 17, reversing the rotation thereof, decreasing a speed of the
rotation thereof, or repeating forward and backward rotation
thereof.
[0129] In the embodiment, the operator does not need to watch any
display or indication of the apparatus in order to know the root
canel information and the load information. Hence the operator can
treat the tooth accurately and precisely, watching only the treated
area.
[0130] Furthermore, a vibrator, which an operator can feel, may be
used in order to inform the operator of the load information and/or
the root canal length information, instead of using the display
device 8 and/or the sound alarm, or combining therewith.
* * * * *