U.S. patent application number 09/063323 was filed with the patent office on 2001-11-22 for rotary magnetic head apparatus having reproduction signal wiring power-supply wiring and recording signal wiring sections in a rotor and a stator arranged in a predetermined manner.
Invention is credited to IKEGAMI, TOMOHIRO, OZUE, TADASHI, SHIRAI, TOSHIO.
Application Number | 20010043421 09/063323 |
Document ID | / |
Family ID | 14512027 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010043421 |
Kind Code |
A1 |
OZUE, TADASHI ; et
al. |
November 22, 2001 |
ROTARY MAGNETIC HEAD APPARATUS HAVING REPRODUCTION SIGNAL WIRING
POWER-SUPPLY WIRING AND RECORDING SIGNAL WIRING SECTIONS IN A ROTOR
AND A STATOR ARRANGED IN A PREDETERMINED MANNER
Abstract
A rotary magnetic head apparatus is provided which can be formed
into a small size even if a plurality of reproduction heads are
provided. The rotary magnetic head apparatus includes a rotary drum
having a rotor of a transmission apparatus and a plurality of
reproduction heads, a fixed drum having a stator of the
transmission apparatus and a plurality of reproduction heads, a
reproduction signal selection device for selecting a reproduction
signal of an information recording medium, which signal is obtained
by each of the reproduction heads and for arranging the
reproduction signal in sequence, a rotor reproduction signal wiring
section which is disposed in the rotor and to which is supplied the
reproduction signal of each of the reproduction heads, which
reproduction signal is sent from the reproduction signal selection
device, and a stator reproduction signal wiring section, which is
disposed in the stator, for receiving the reproduction signal from
the rotor reproduction signal wiring section without contact.
Inventors: |
OZUE, TADASHI; (KANAGAWA,
JP) ; SHIRAI, TOSHIO; (KANAGAWA, JP) ;
IKEGAMI, TOMOHIRO; (CHIBA, JP) |
Correspondence
Address: |
FROMMER LAWRENCE & HAUG
745 FIFTH AVENUE- 10TH FL.
NEW YORK
NY
10151
US
|
Family ID: |
14512027 |
Appl. No.: |
09/063323 |
Filed: |
April 20, 1998 |
Current U.S.
Class: |
360/61 ;
G9B/15.016; G9B/15.018 |
Current CPC
Class: |
G11B 2005/0016 20130101;
G11B 15/12 20130101; G11B 15/14 20130101 |
Class at
Publication: |
360/61 |
International
Class: |
G11B 015/12; G11B
015/14 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 25, 1997 |
JP |
9-109507 |
Claims
What is claimed is:
1. A rotary magnetic head apparatus which records a signal onto a
tape-like information recording medium and reproduces a signal of a
tape-like information recording medium, said rotary magnetic head
apparatus comprising: a transmission apparatus for transmitting
power and signals in a non-contact manner between a rotor and a
stator; a rotary drum having a rotor of a transmission apparatus
and a recording head; a fixed drum of the rotary magnetic head
apparatus having a stator of the transmission apparatus and a
plurality of reproduction heads; reproduction signal selection
means for selecting a reproduction signal of the information
recording medium, which reproduction signal is obtained by each
reproduction head and for arranging the reproduction signal in
sequence; a rotor reproduction signal wiring section which is
disposed in the rotor and to which is input a reproduction signal
of each reproduction head, which reproduction signal is sent from
the reproduction signal selection means; and a stator reproduction
signal wiring section, which is disposed in the stator, for
receiving a reproduction signal in a non-contact manner from the
rotor reproduction signal wiring section.
2. A rotary magnetic head apparatus according to claim 1, wherein
the reproduction signal selection means comprises: rotation
detection means for detecting a rotation of the rotary drum; and
selection signal generation means for generating a selection signal
for selecting a reproduction signal of each reproduction head in
accordance with a detection signal generated by the rotation
detection means.
3. A rotary magnetic head apparatus according to claim 2, wherein
the rotation detection means comprises: a magnet mounted to the
rotary drum; and a magnetic sensor, which is provided in the rotary
drum, for detecting the magnetism of the magnet.
4. A rotary magnetic head apparatus according to claim 1, wherein
the rotary drum includes a plurality of recording heads, the stator
of the transmission apparatus includes: a stator reproduction
signal wiring section, a stator power-supply wiring section for
supplying power, and a plurality of stator recording signal wiring
sections, which are disposed between the stator reproduction signal
wiring section and the stator power-supply wiring section, to which
is input a recording signal for each recording head, and the rotor
of the transmission apparatus includes: a rotor reproduction signal
wiring section, a rotor power-supply wiring section for
transmitting power, and a plurality of rotor recording signal
wiring sections, which are disposed between the rotor reproduction
signal wiring section and the rotor power-supply wiring section,
for receiving a recording signal from each stator recording signal
wiring section without contact.
5. A rotary magnetic head apparatus according to claim 4, wherein
the times that each recording head contacts a tape-like information
recording medium do not overlap each other.
6. A rotary magnetic head apparatus according to claim 1, wherein
in the reproduction signal selection means for selecting a
reproduction signal of each reproduction head, a plurality of
output sections of a reproduction amplifier having incorporated
therein an output enable logic circuit are connected directly in
parallel to the rotor reproduction signal wiring section on the
rotor side of the transmission apparatus.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a rotary magnetic head
apparatus comprising a non-contact-type transmission apparatus for
use in an information writing apparatus, such as a video tape
recorder.
[0003] 2. Description of the Related Art
[0004] Apparatuses for recording information onto a magnetic tape
and reproducing information of a magnetic tape include video tape
recorders, tape streamers, and the like. Such types of information
writing apparatus comprise a rotary magnetic head apparatus for the
purpose of recording a signal onto a magnetic tape and reproducing
a signal of a magnetic tape.
[0005] The rotary magnetic head apparatus includes a rotary drum
and a fixed drum, and the rotary drum includes a recording head and
a reproduction head. The recording head is a head for recording a
signal onto a magnetic tape, and the reproduction head is used to
reproduce a signal recorded on a magnetic tape.
[0006] The rotary drum, which houses the recording head and the
reproduction head, is rotated by the actuation of a motor with
respect to the fixed drum, causing the recording head or the
reproduction head to scan the magnetic tape, for example, by a
helical scan method. Thus, information can be recorded onto a
magnetic tape or information of a magnetic tape can be reproduced
along the recording tracks by a tracking reproduction method.
[0007] By adopting such a helical scan method, high-density
recording of a signal onto a magnetic tape is made possible, and
the relative speed between the magnetic tape and the magnetic head
can be increased.
[0008] In the rotary magnetic head apparatus of a helical scan
method, since the recording head and the reproduction head are
housed inside the rotary drum, signals and power must be exchanged
between this rotary drum and a fixed drum by a non-contact method;
for example, in the case when a reproduction signal obtained from
the reproduction head is transmitted from the rotary drum to the
fixed drum in a non-contact manner, or when power for a circuit
substrate is supplied from the fixed drum to the rotary drum.
[0009] In this type of rotary magnetic head apparatus used in the
conventional art, non-contact-type transmission of a signal system
uses a rotary transformer dedicated to the signal system, and in
order to supply power without contact, another rotary transformer
for power supply is required. The reason why a rotary transformer
of a signal system and another rotary transformer for power supply
are prepared in this manner is to prevent crosstalk of a
transmission signal used for the rotary transformer for power
supply to the rotary transformer side of the signal system.
[0010] This crosstalk refers to leakage of a signal due to a
leakage magnetic-field between the adjacent signal system and
power-supply system or between different signal systems.
[0011] However, the rotary magnetic head apparatus comprising two
rotary transformers is enlarged, the cost increases, and in
addition it is difficult to mount two rotary transformers to a
small rotary magnetic head apparatus.
[0012] Also, in the rotary transformer, often, one transmission
channel of the rotary transformer is assigned to a respective
reproduction heads and a reproduction signal system thereof.
However, while there has been a demand for an increase in the
amount of recording data and a higher transfer rate, it is expected
that the number of reproduction heads mounted in a rotary drum and
the number of channels of the reproduction signal system will be
greater in the future. In the current situation where one
transmission channel of the rotary transformer is assigned to one
reproduction head and one reproduction signal system, the rotary
transformer is enlarged, causing the rotary drum to is enlarged.
Therefore, it is difficult to mount such a rotary magnetic head
apparatus including a plurality of reproduction heads and
reproduction head signal systems to a small information apparatus,
and greater costs are incurred.
SUMMARY OF THE INVENTION
[0013] Accordingly, an object of the present invention, the
achievement of which solves the above-described problems, is to
provide a rotary magnetic head apparatus which can be formed into a
small size even if a plurality of reproduction heads are
provided.
[0014] To achieve the above-described object, according to the
present invention, there is provided a rotary magnetic head
apparatus which records a signal onto a tape-like information
recording medium and reproduces a signal of a tape-like information
recording medium, said rotary magnetic head apparatus comprising: a
transmission apparatus for transmitting power and signals in a
non-contact manner between a rotor and a stator; a rotary drum
having a rotor of a transmission apparatus and a recording head; a
fixed drum having a stator of a transmission apparatus and a
plurality of reproduction heads; reproduction signal selection
means for selecting a reproduction signal of the information
recording medium obtained by each reproduction head and for
arranging the reproduction signal in sequence; a rotor reproduction
signal wiring section which is disposed in the rotor and to which
is input a reproduction signal of each reproduction head, which
reproduction signal is sent from the reproduction signal selection
means; and a stator reproduction signal wiring section, which is
disposed in the stator, for receiving a reproduction signal without
contact from the rotor reproduction signal wiring section.
[0015] In the present invention, the rotary drum of the rotary
magnetic head apparatus includes a rotor of a transmission
apparatus and a recording head. The fixed drum of the rotary
magnetic head apparatus includes a stator of the transmission
apparatus and a plurality of reproduction heads. The reproduction
signal selection means is capable of selecting a reproduction
signal of an information recording medium, which reproduction
signal is obtained by each reproduction head. Supplied to the rotor
reproduction signal wiring section is a reproduction signal of each
reproduction head, which signal is sent from the reproduction
signal selection means. The stator reproduction signal wiring
section is designed to receive the reproduction signal from each
rotor reproduction signal wiring section without contact.
[0016] As a result of the above, since the reproduction signal
obtained by a plurality of reproduction heads is selected and
arranged in sequence by the reproduction signal selection means, it
is not necessary to provide rotor reproduction signal wiring
sections and stator reproduction signal wiring sections
corresponding to the number of reproduction heads. That is, since
the reproduction signal transmission system for a reproduction
signal from each reproduction head, which reproduction signal is
arranged by the reproduction signal selection means, needs to be
prepared, for example, for one channel, it is possible to decrease
the number of channels of the rotor reproduction signal wiring
section and the stator reproduction signal wiring section for the
purpose of transmission without contact.
[0017] The above and further objects, aspects and novel features of
the invention will become more apparent from the following detailed
description when read in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a perspective view showing a rotary magnetic head
apparatus of the present invention.
[0019] FIG. 2 is a plan view showing an example of an information
writing apparatus including the rotary magnetic head apparatus of
FIG. 1.
[0020] FIG. 3 shows an example of the construction of the rotary
magnetic head apparatus of FIG. 1, in which an incorporated rotary
transformer is of a plane-opposing type.
[0021] FIG. 4 shows another example of the construction of the
rotary magnetic head apparatus of FIG. 1, in which an incorporated
rotary transformer is of a cylindrical type.
[0022] FIG. 5 is a perspective view showing the rotary transformer
of FIG. 3.
[0023] FIG. 6 is a perspective view showing the rotary transformer
of FIG. 4.
[0024] FIG. 7 is a partly omitted, sectional view showing an
example of the construction of the rotary transformer of FIG.
5.
[0025] FIG. 8 shows the rotary transformer of FIG. 7, and the
surrounding arrangement of the rotary transformer.
[0026] FIG. 9 shows selection signal generation means for
generating a select signal SE of a reproduction head, a plurality
of reproduction heads, and the like in the rotary magnetic head
apparatus of the present invention.
[0027] FIG. 10 shows examples of the waveform of the select signal
SE, and select signals SEA and SEB of the reproduction head in FIG.
9.
[0028] FIGS. 11A, 11B, and 11C show examples of an output from a
magnetic sensor, an output after waveform is shaped, an output from
a delay circuit, and an output from a monostable multivibrator
circuit.
[0029] FIG. 12 shows examples of a magnetic sensor provided in a
rotary drum and a magnet provided in a fixed drum.
[0030] FIG. 13 shows an example of the arrangement of the magnet of
the fixed drum, and an example of the relationship between a delay
time d and an angle .theta..
[0031] FIGS. 14A and 14B show an example in which reproduction
signals obtained by a plurality of reproduction heads are
synthesized for one channel.
[0032] FIG. 15 shows another embodiment of the rotary magnetic head
apparatus of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] The preferred embodiments of the present invention will be
described below in detail with reference to the accompanying
drawings.
[0034] Since the embodiments to be described below are preferred
specific examples of the present invention, various technically
preferred limitations are imposed. However, the present invention
is not limited to these embodiments unless a description limiting
the present invention is given in the following description.
[0035] FIG. 1 shows a preferred embodiment of a rotary magnetic
head apparatus of a tracking method comprising a non-contact-type
transmission apparatus of the present invention. FIG. 2 shows an
example of an information writing apparatus comprising a rotary
magnetic head apparatus 10.
[0036] The rotary magnetic head apparatus 10 of FIGS. 1 and 2 is
applicable to a video tape recorder, a data streamer, a digital
audio system, and the like, and is used to record a signal onto
recording tracks of a magnetic tape TP which is a tape-like
recording medium by a tracking method and to reproduce information
recorded on the magnetic tape TP.
[0037] The rotary magnetic head apparatus of FIGS. 1 and 2 includes
a fixed drum 1, a rotary drum 2, and a motor M.
[0038] The rotary drum 2 has, for example, two reproduction heads
RH1 and RH2, and two recording heads WH1 and WH2. Each of the
reproduction heads RH1 and RH2 has a phase difference of 90
degrees, and each of the recording heads WH1 and WH2 has a phase
difference of 90 degrees. The rotary drum 2 rotates in the
direction of the arrow R with respect to the fixed drum 1 by the
actuation of the motor M. The rotary drum 2, and the recording head
WH and the reproduction head RH rotate in the R direction. The
magnetic tape TP is fed obliquely along a tape feeding direction E
from an entry side IN to an exit side OUT along a lead guide
section 3 of the fixed drum 1.
[0039] In the information recording apparatus in FIG. 2, the
magnetic tape TP is brought into close contact with almost 180
degrees of the rotary drum 2 and the fixed drum 1, after being
through rollers 4a, 4b, and 4c from a supply reel 4, and can be
taken up by a take-up reel 5 after being through the rollers 4d,
4e, 4f, and 4g. A capstan 4h is provided so that it corresponds to
the roller 4f, and this capstan 4h is rotated by a capstan motor
M1.
[0040] As a result, when the motor M is actuated and the rotary
drum 2 is rotated in the R direction, the recording heads WH1 and
WH2 and the reproduction heads RH1 and RH2 are brought into contact
with the magnetic tape TP by a helical scan method and guided. The
magnetic tape TP is fed obliquely along the lead guide section 3 of
the fixed drum 1.
[0041] An example of the construction of this rotary magnetic head
apparatus 10 is shown in FIGS. 3 and 4.
[0042] The rotary magnetic head apparatus 10 of FIG. 3 comprises a
rotary transformer T which is a non-contact-type transmission
apparatus. This rotary transformer T is disposed between the rotary
drum 2 and the fixed drum 1. That is, the rotary transformer T is
incorporated within the rotary magnetic head apparatus 10.
[0043] The rotary magnetic head apparatus 10 is also called a
rotary drum apparatus, and two bearings 1b are disposed within a
sleeve 1a of the fixed drum 1. The fixed drum 1 has fixed thereto a
stator core 20 which is a stator of the rotary transformer T.
[0044] The rotary drum 2 has a flange 2a, and this flange 2a is
fixed to the upper end portion of the shaft 5 by press-fitting or
bonding. The lower end portion of the shaft 5 is fixed to a rotor
MR of the motor M. The motor M includes the rotor MR and a stator
MS. The rotor MR is provided with, for example, a driving magnet 6,
and the stator MS is provided with a driving coil 7. By supplying
power to this coil 7 in a predetermined pattern, the rotor MR of
the motor M is rotated continuously.
[0045] The intermediate portion of the shaft 5 is rotatably
supported by bearings 1b and 1b. Inside the flange 2a, a rotor core
30, which is a rotor of the rotary transformer T, is fixed.
[0046] The rotary transformer T of FIG. 3 is formed of a stator
core 20 (stator) and a rotor core 30 (rotor), which are each a
circular-plate-shaped core as shown in FIG. 5, and is made from a
magnetic-permeable material, such as ferrite.
[0047] The stator core 20 and the rotor core 30 are formed in a
ring form so that the sleeve 1a of FIG. 3 can be passed
therethrough. Channels CH1 to CH4 for signal transmission are
disposed in a ring form on the internal surface (the top surface in
FIG. 3) of the stator core 20 and on the internal surface (the
bottom surface in FIG. 3) of the rotor core 30 with the shaft 5 as
the center, as will be described later.
[0048] The wiring section where these channels CH1 to CH4 are
formed may be formed by winding a conventional, insulated wire
material in a ring form, or a printed-wiring board may be used.
[0049] As a result, when power is supplied to the coil 7 of the
stator MS of the motor M, the rotor MR of the motor M, the shaft 5,
the flange 2a, the rotary drum 2, and the rotor core 30 of the
rotary transformer T rotate with respect to the fixed drum 1 and
the stator core 20. The rotor core 30 and the stator core 20 are
disposed in such a manner as to oppose each other in a non-contact
manner.
[0050] Meanwhile, in the rotary magnetic head apparatus 10 of FIG.
4, a cylindrical stator core 120 such as that shown in FIG. 6 is
fixed to the fixed drum 1. A rotor core 130 of a rotary transformer
T1 is fixed to the flange 2a of the rotary drum 2. The stator core
120 and the rotor core 130 are disposed coaxially with the shaft 5
as the center, and the outside diameter of the stator core 120 is
set to be smaller than the internal diameter of the rotor core 130.
As a result, the outer surface of the stator core 120 and the inner
surface of the rotor core 130 are placed in a non-contact manner
with a predetermined gap. The channels CH1 to CH4 of the rotary
magnetic head apparatus 10 of FIG. 4 are formed in a ring form in
an axial direction.
[0051] When power is supplied in a predetermined power-supply
pattern to the coil 7 of the stator MS of the motor M, the rotor MR
of the motor M, the shaft 5, the flange 2a, and the rotor core 130
of the rotary transformer T1 rotate in a non-contact manner with a
predetermined gap with respect to the fixed drum 1 and the stator
core 120.
[0052] The non-contact-type transmission apparatus of the present
invention can be applied to both the plane-opposing-type rotary
transformer T such as that shown in FIG. 3 and the cylindrical-type
rotary transformer T1 such as that shown in FIG. 4.
[0053] Next, referring to FIGS. 7 and 8, a description will be
given of an example of the wiring construction of the rotary
transformer T shown in FIGS. 3 and 5, and the surrounding
arrangement of the rotary transformer T.
[0054] Since the right and left portions of the rotary transformer
T shown in FIG. 7 are symmetrical, a part thereof is omitted, the
stator core 20 and the rotor core 30 are disposed opposite to each
other, and a predetermined gap CM is set.
[0055] The internal surface 21 of the stator core 20 is formed
with, for example, four grooves 21a, 21b, 21c, and 21d coaxially
with the center axis CL as the center from the inner peripheral
side to the outer peripheral side. Similarly, an internal surface
31 of the rotor core 30 is formed with, for example, grooves 31a,
31b, 31c, and 31d coaxially with the center axis CL as the center.
These grooves 21a to 21d and the grooves 31a to 31d are at opposing
positions to each other.
[0056] Reproduction signal transmission rings RR are disposed in
the grooves 21a and 31a, and recording signal transmission rings WR
are disposed in the grooves 21b and 31b. Recording signal
transmission rings WR are disposed in the grooves 21c and 31c, and
power transmission rings PR are disposed in the grooves 21d and
31d.
[0057] The reproduction signal transmission rings RR, the recording
signal transmission rings WR and WR, and the power transmission
rings PR are each produced by winding, for example, an insulating,
coated wire material into a ring form for a plurality of times. The
rotor core 30 and the stator core 20 themselves are produced into a
circular-plate form or a ring form in a magnetic-permeable
material, such as ferrite. The reproduction signal transmission
rings RR and the recording signal transmission rings WR are a
signal transmission system, and the power transmission rings are a
power-supply system.
[0058] FIG. 8 shows the rotary transformer T, and the functional
portions surrounding the rotary transformer T.
[0059] The rotary transformer T of FIG. 8 is shown differently to
the rotary transformer T of FIG. 7, and the channels CH1 to CH4 are
drawn in the vertical direction in FIG. 8.
[0060] As shown in FIGS. 8 and 7, the feature is that in the rotary
transformer T, two areas, a power-supply area for the power
transmission rings PR, a signal area for the reproduction signal
transmission rings RR and the recording signal transmission rings
WR are present separately. The area for the power transmission
rings PR, and the reproduction signal transmission ring RR are
separated by the area of the two recording signal transmission
rings WR and WR.
[0061] These two recording signal transmission rings WR and WR
serve as a crosstalk prevention section of the rotor core 30 and a
crosstalk prevention section of the stator core 20 for preventing
crosstalk in the area between the power transmission ring PR and
the reproduction signal transmission ring RR.
[0062] In FIG. 8, the power transmission ring PR of the stator core
20 inside the power transmission ring PR of the channel CH4 is
connected to an oscillator 41 via a power drive 40. The direct
current with a high frequency generated by this oscillator 41 is
converted into an alternating current, and the power drive 40
supplies the alternating current to the power transmission ring PR
of the stator core 20. The power transmission ring PR of the stator
core 20 transmits the alternating current to the power transmission
ring PR of the rotor core 30 in a non-contact manner, the
transmitted alternating current is rectified into direct current by
a rectifier 42, and the direct current is set to a desired voltage
by a regulator 43a.
[0063] The current set to the voltage from the regulator 43a is
preferably supplied to the reproduction amplifiers 43A and 43B of
the reproduction heads RH and used to amplify the reproduction
current obtained by the reproduction heads RH1 and RH2. Also, the
current of the regulator 43a can be supplied to reproduction signal
selection means 200, which will be described later.
[0064] The reproduction heads RH1 and RH2 reproduce information of
the magnetic tape TP of FIG. 1 and sends the reproduction signal RS
to the reproduction amplifiers 43A and 43B, and the reproduction
signal RS amplified by the reproduction amplifiers 43A and 43B is
sent to the reproduction signal transmission ring RR of the rotor
core 30 of the channel CH1. The amplified reproduction signal RS is
sent from the reproduction signal transmission ring RR of the rotor
core 30 without contact to the reproduction signal transmission
ring RR of the stator core 20. On the stator core 20 side, the sent
reproduction signal RS is further amplified by the reproduction
amplifier 44.
[0065] A recording amplifier 45 on the fixed drum 1 side of FIG. 8
sends recording current from the recording signal source to the
recording signal transmission rings WR and WR of the channels CH2
and CH3 of the stator core 20. When the recording signal WS is sent
from the recording signal transmission ring WR of the stator core
20 to the recording signal transmission ring WR of the rotor core
30, this recording current is directly sent from the recording
signal transmission ring WR of the rotor core 30 to the recording
heads WH1 and WH2.
[0066] Since, as described above, the recording heads WH1 and WH2
are directly connected to the recording signal transmission ring WR
of the rotor core 30, it is possible to decrease the impedance in
the low-frequency region in the recording signal system formed of
the recording heads WH1 and WH2 in the low-frequency region and the
recording signal transmission ring WR of the rotor core 30.
[0067] The recording signal transmission rings WR and WR disposed
in the channels CH2 and CH3 are capable of preventing crosstalk
between the reproduction system of channel CH1 and the
power-transmission system of channel CH4. That is, the recording
signal transmission rings WR and WR reduce crosstalk from the
power-transmission system of the channel CH4 to the reproduction
signal system of the channel CH1.
[0068] Switching means 50 of FIG. 8 is a switching means for
turning on/off the actuation of the oscillator 41. This switching
means 50 turns on or off the oscillation actuation for supplying
power by turning on or off the oscillator 41. The reason why the
oscillator 41 is turned on/off in this manner is as follows.
[0069] When the recording heads WH1 and WH2 are in contact with the
magnetic tape TP (during signal recording), the switching means 50
turns off the oscillator 41, and when the recording heads WH1 and
WH2 are not in contact with the magnetic tape TP (during signal
reproduction), the switching means 50 turns on the oscillator
41.
[0070] When the recording heads WH1 and WH2 are in contact with the
magnetic tape TP, that is, when the recording heads WH1 and WH2 are
recording a signal onto the magnetic tape TP, the reproduction
heads RH1 and RH2 are not reproducing a signal of the magnetic tape
TP. Therefore, since there is no need to supply power to the
reproduction amplifier 43 of FIG. 8 from the oscillator 41, the
oscillator 41 is turned off. In comparison, when the recording
heads WH1 and WH2 are not in contact with the magnetic tape TP,
that is, when the reproduction heads RH1 and RH2 are reproducing a
signal of the magnetic tape TP, the oscillator 41 is turned on and
power is supplied from the regulator 43a to the reproduction
amplifier 43, making it possible to amplify the reproduction signal
RS of the reproduction heads RH1 and RH2.
[0071] Therefore, since in a state in which the recording heads WH1
and WH2 are in contact with the magnetic tape TP, the oscillator 41
is turned off, it is possible to reliably prevent crosstalk from
the power system of the channel CH4 to the reproduction signal
system of the channel CH1 in FIG. 8.
[0072] In the oscillator 41, in the case where direct current is
converted into alternating current and the alternating current is
converted again into direct current by the rectifier 42, a method
of preventing crosstalk from the power system of the channel CH4 to
the recording signal system (the reproduction signal system of the
channel CH1) of the channels CH2 and CH3 can be adopted in such a
way that the highest frequency band of the alternating current (AC)
does not overlap with the frequency band of the recording signal of
the channels CH2 and CH3.
[0073] Referring to 8, a description will be given of the
reproduction heads RH1 and RH2 and the channel CH1 of the
reproduction system in more detail.
[0074] The two reproduction heads RH1 and RH2 are connected to the
reproduction amplifiers 43A and 43B, respectively. The reproduction
heads RH1 and RH2 can transmit the reproduction signal RS from the
tape-like information recording medium (magnetic tape TP) to the
reproduction amplifier 43A or 43B. The output terminals of the
reproduction amplifiers 43A and 43B are each electrically connected
to one reproduction signal transmission ring RR of the rotor core
30. Also, the reproduction signal transmission ring RR of the
stator core 20 is connected to the reproduction amplifier 44, and
this reproduction amplifier 44 is connected to a signal processing
section at a stage after an adjustment circuit.
[0075] As shown in FIGS. 8 and 9, in the reproduction signal
selection means 200 for selecting reproduction signals RS and RS of
each of the reproduction heads RH1 and RH2, the output section of a
plurality of ICs (integrated circuits) of the reproduction
amplifiers 43A and 43B having an output enable logic circuit
incorporated therein is directly connected in parallel to the
reproduction signal transmission ring RR (the rotor reproduction
signal wiring section) of the rotor core 30 (on the rotor side) of
the transmission apparatus.
[0076] The particular feature in FIG. 8 is that the reproduction
signal selection means 200 is connected to the reproduction
amplifiers 43A and 43B. This reproduction signal selection means
200 is a means for selecting the reproduction signals RS and RS of
the tape-like information recording medium obtained by each of the
reproduction heads RH1 and RH2 and arranging the reproduction
signals in sequence.
[0077] This reproduction signal selection means 200 has the
following elements. A magnetic sensor 201 and a magnet 202 form
rotation detection means 203 for detecting the rotation of the
rotary drum 2. The magnetic sensor 201 of this rotation detection
means 203 is fixed to the rotary drum 2, as shown in FIG. 12, and
the magnet 202 is fixed to the fixed drum 1. As a result of the
magnetic sensor 201 rotating with respect to the fixed drum 1
together with the rotary drum 2 and detecting the magnetism of the
magnet 202, a magnetic sensor output MSA shown in FIG. 11A can be
output for each rotation. As shown in FIG. 13, the distance between
the magnet 202 fixed to the fixed drum 1 and the center CL of the
fixed drum 1 is indicated by a letter a. Also, as shown in FIG. 12,
the angle between the magnetic sensor 201 of the rotary drum 2 and
the reproduction head RH1 is indicated by .theta.. As shown in FIG.
13, while the rotary drum 2 is rotating at a fixed speed v, the
relationship between a delay time d and an angle .theta. between
the magnetic sensor 201 and the reproduction head RH1 is as
follows:
d=(2.pi.a.times..theta./360.degree.)/v.
[0078] This delay time d is a time for making a delay from the rise
time T1 of the magnetic sensor output MSA, as shown in FIG.
11C.
[0079] Referring back to FIG. 8, the magnetic sensor 201 of the
reproduction signal selection means 200 is connected to selection
signal generation means 205, as shown in FIGS. 8 and 9. This
selection signal generation means 205 includes a shaping circuit
206, a delay circuit 207, and a monostable multivibrator circuit
208.
[0080] Referring to FIGS. 9 and 11, the magnetic sensor output MSA
that the magnetic sensor 201 detects the magnetism of the magnet
202 of FIG. 12 and outputs is input to the shaping circuit 206 of
the selection signal generation means 205, and an output SA after
the waveform, shown in FIG. 11B, is shaped is output.
[0081] The delay circuit 207 of FIG. 9 outputs an output DA after
the delay circuit, shown in FIG. 1C, at a time T2 delayed by a
delay time d from the time T1.
[0082] The monostable multivibrator circuit 208 outputs an output
MAO after the monostable multivibrator circuit, shown in FIG. 11D,
in accordance with this output DA after the delay circuit. This
output MAO after the monostable multivibrator circuit is a
rectangular waveform having a predetermined pulse width PW, and an
output MAO (+) after the monostable multivibrator circuit is a
select signal SE of the reproduction head shown in FIG. 9 for
selecting the reproduction heads RH1 and RH2. This select signal SE
of the reproduction head is directly input as a select signal SEA
to the reproduction amplifier 43A of the reproduction head RH1, as
shown in FIGS. 8 and 9, and the select signal SE of the
reproduction head is also input as a select signal SEB to the
reproduction amplifier 43B of the reproduction head RH2 via an
inverter IVT.
[0083] As shown in FIG. 10, this select signal SEA is a pulse
synchronized with the select signal SE of the reproduction head,
whereas the select signal SEB is a signal inverted with respect to
the select signal SE of the reproduction head.
[0084] As a result, the reproduction signals RS of the reproduction
heads RH1 and RH2 are supplied to the reproduction signal
transmission ring RR which is a rotor reproduction signal wiring
section shown in FIGS. 8 and 9 in such a way that the reproduction
signals are arranged alternately in sequence in the manner shown in
FIGS. 14A and 14B. From the reproduction signal transmission ring
RR of the rotor core 30 which is a rotor reproduction signal wiring
section, the reproduction signals of the two reproduction heads RH1
and RH2 can be sent without contact to the reproduction signal
transmission ring RR of the stator core 20 which is a stator
reproduction signal wiring section in such a way that the
reproduction signals are arranged in sequence. That is, even if
there are two reproduction heads RH1 and RH2, if there is one
channel CH1 of the reproduction system, it is possible to send the
reproduction signal RS to the reproduction amplifier 44.
[0085] FIGS. 14A and 14B show an example in which the reproduction
signals RS obtained by the two reproduction heads RH1 and RH2 in
this way are arranged into one channel.
[0086] In FIGS. 2 and 8, the reproduction head RH1 (R+) and the
reproduction head RH2 (R-) show that the magnetic gaps thereof have
a +azimuth angle and a -azimuth angle, respectively. Also, the
recording head WH1 (W+) and the recording head WH2 (W-) show that
the magnetic gaps thereof have a +azimuth angle and a -azimuth
angle, respectively.
[0087] Next, another embodiment of the present invention will be
described briefly with reference to FIG. 15.
[0088] Since the embodiment of FIG. 15 is substantially the same as
the embodiment of FIG. 8, components in FIG. 15 which are the same
as those in FIG. 8 are given the same reference numerals, and a
description thereof has been omitted.
[0089] The difference of the embodiment of FIG. 15 from the
embodiment of FIG. 8 is that short rings SR and SR which are
crosstalk prevention sections are actively disposed between the two
recording heads WH1 and WH2 (the recording channels CH2 and CH3),
and the power transmission channel CH5. That is, the short ring SR
is disposed in the rotor core 30, and the short ring SR is also
disposed in the stator core 20.
[0090] The short rings SR and SR disposed in this channel CH4 are
each a short-circuit-type ring, which can prevent crosstalk between
the reproduction system of the reproduction channel CH1 of the
channel CH1, and the power transmission system of the recording
heads WH1 and WH2 and the channel CH4. As is well known, these
short rings SR and SR can cancel a leakage magnetic-field between
the adjacent power transmission channel CH5 and the reproduction
channel CH1 or the recording channels CH2 and CH3, and suppress
leakage of a signal (commonly called crosstalk) from the power
transmission channel CH5 with a large power to the reproduction
channel CH1 and the channels CH2 and CH3 with a small power.
[0091] Although the above embodiments of the present invention
describe a plane-opposing-type rotary transformer T shown in FIG.
2, in addition to this, the above-described embodiments are
applicable to the cylindrical-type rotary transformer T1 shown in
FIGS. 4 and 6.
[0092] In the rotary transformer which is a non-contact-type
transmission apparatus of the embodiment of the present invention,
since both a signal area and a power area are provided, and a
crosstalk prevention section is provided between them, it is
possible to transmit both signals and power reliably without
contact. As a result, a first-stage reproduction amplifier may be
provided in the drum of the rotary magnetic head apparatus so as to
prevent deterioration of the S/N ratio.
[0093] In the embodiments shown in the figures, since the
construction is formed such that power is supplied from the power
system to the reproduction amplifier 43 of the reproduction system,
as the reproduction head RH, for example, a magneto-resistive
element head (MR) may be used. The magneto-resistive element head
(MR) for reproduction always requires a bias current when a
reproduction signal is to be obtained, and by sending a bias from
the regulator 43a to the reproduction amplifier 43, the
magneto-resistive element head can be operated to obtain the
reproduction signal. This magneto-resistive element head is a head
for causing variation the resistance when the magnetic field is
varied. The magneto-resistive element head converts variation in
the signal magnetic-field (input signal) into resistance variation
and pick it up as a variation in the reproduction output signal
(voltage).
[0094] This magneto-resistive element head is capable of obtaining
a highly stable reproduction output signal without depending upon
the speed of the magnetic tape TP.
[0095] In the embodiments of the present invention, the design is
formed such that the times in which the plurality of reproduction
heads RH1 and RH2 contact a tape-like information recording medium
do not overlap with each other, and an amplifier for reproduction
is connected to each of the reproduction heads RH1 and RH2. After
the reproduction signal RS is amplified by this amplifier, the
reproduction signal is arranged in sequence as the reproduction
signal RSA arranged as shown in FIG. 14B by the reproduction signal
selection means 200 functioning as a switching circuit and formed
into the reproduction signal of one channel. After being formed
into the reproduction signal of one channel, the reproduction
signal of one channel is sent to the signal processing section side
without contact via the rotary transformer.
[0096] That is, since the contact of the plurality of reproduction
heads RH1 and RH2 with the tape-like information recording medium
is independent in relation to time, the reproduction signal RS can
be formed into one channel by switching the reproduction signal RS
after being amplified.
[0097] As described in FIGS. 11A and 11B to 13, the magnetic sensor
201 at a position of an angle .theta. from one reproduction head
RH1 causes the output SA after the waveform is shaped to be delayed
by a delay time d, which can be computed on the basis of the
positional relationship of the magnetic sensor 201, as shown in
FIG. 11B by the delay circuit 207 shown in FIG. 9, and the output
DA after the delay circuit is obtained. The select signal SE of the
reproduction head, which is an output after the monostable
multivibrator circuit, shown in FIG. 1D, is output in
synchronization with this output DA after the delay circuit. By
appropriately adjusting the duty of the high portion corresponding
to the reproduction head RH1 of the select signal SE of this
reproduction head to the low portion corresponding to reproduction
head RH2, optimization is possible by causing select signals SE of
the two reproduction heads RH1 and RH2 to have the same width.
[0098] As described above, the reproduction signal selection means
200 shown in FIGS. 8 and 9 is designed to output a select signal
having an output of commonly called exclusive OR.
[0099] When the plurality of recording heads of FIG. 8 do not
require a RSW (Read after Write) mode, the recording heads are
designed to interpose a plurality of recording channels between the
power channel and the reproduction channels by using the fact that
the times in which each recording head contacts the tape are
independent in relation to time. This RSW mode is a mode in which
after information is recorded, the recorded information is
immediately reproduced and confirmed. The reproduction signal
selection means 200 such as that shown in FIG. 8 can be realized
with a relatively simple circuit.
[0100] Although the embodiments of the present invention describe
an example in which two reproduction heads are used, in addition to
this example, it is a matter of course that the present invention
is applicable to a case in which three or more reproduction heads
are provided. Also, although two recording heads are shown in the
figures, in addition to this example, it is a matter of course that
the present invention is applicable to a case in which three or
more recording heads, or only one recording head is used.
[0101] Many different embodiments of the present invention may be
constructed without departing from the spirit and scope of the
present invention. It should be understood that the present
invention is not limited to the specific embodiments described in
this specification. To the contrary, the present invention is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the invention as hereafter
claimed. The scope of the following claims is to be accorded the
broadest interpretation so as to encompass all such modifications,
equivalent structures and functions.
* * * * *