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JPS4933641

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DESCRIPTION JPS4933641
■ Pick-up device ■ Japanese Patent Application No. 45-96422 [Phase] Application No. 45
(1970) November 4 @ inventor Watanabe Shoji Shin-shiko-cho 33, Shishi-ku, Yokohama-shi
Tokyo Shibaura Electric Co., Ltd. Sound factory in Shibata Electric Co., Ltd. Hiroyuki Imazeki ■
Applicant Tokyo Shibaura Electric Co., Ltd. Kawasaki City, Kawasaki-ku Horikawacho, 72 [Fa]
Agent Attorney Akira Tomioka 3 people
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing an embodiment of a
pickup device according to the present invention, FIGS. 2 and 3 are a bottom view and a front
view of the same, and FIG. The figure is a perspective view of the outer housing, FIG. 6 is a
perspective view showing the support upside down, and FIG. 7 is a perspective view showing the
mechanical support upside down with the fixed pole attached, FIG. FIGS. 10A and 10B are a
bottom view, a side view and a rear view showing an opposing state of the movable pole and the
fixed pole, and FIG. 11 is a perspective view showing the conversion mechanism part upside
down.
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pickup device
for a record player, and more particularly to a pickup device of a capacitor type. In a capacitor
type pickup device, electromechanical conversion is carried out utilizing the change in the
electrical properties of the capacitor, for example, the capacity or impedance, in response to the
change in the relative positional relationship between the two electrode plates forming the
capacitor. Use the nature of a capacitor-type transducer that Conventionally, there are various
problems [111111] in the case of constructing a pickup device using this capacitor type
transducer, and it has been extremely difficult to obtain stable performance with a simple
structure. For example, in the case of utilizing the property that the capacitance of the capacitor
changes in response to a mechanical change in the relative positional relationship of the
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electrode plates, an alternating current system is used which forms a resonant circuit with the
coil and frequency modulates the resonant frequency. However, in such an alternating current
system, the resonance frequency is easily fluctuated (the performance is extremely unstable) due
to the surrounding thermal factor and the like. Further, in the case of a direct current method
using impedance change, the impedance of the capacitor itself is extremely high impedance, so
that in the prior art it is easy to pick up external induction noise etc. (and a circuit for requiring a
DC bias power supply added to the capacitor) Had the drawback of becoming complicated. The
present invention has been made in view of the disadvantages of the conventional pickup device
of this type, and uses a direct current method utilizing impedance change to eliminate the
conventional defects found in this method, and has a stable performance and an extremely
simple structure. A pickup device having a novel structure in which the capacitor section is
sufficiently reduced in external inductive noise accompanied by high impedance and the
impedance at the output end is lowered to improve the SN ratio It is. Hereinafter, an embodiment
of a pickup rod according to the present invention will be described with reference to the
drawings. That is, as shown in FIG. 1 to FIG. 3, the pickup device of this embodiment is
detachably supported by a base portion 先端 attached to the tip end portion of a pickup arm (not
shown) And a conversion mechanism unit. The base 1 has wings 4 and 4 for attachment to a
pickup arm on both sides, and terminal pins 5 and 5 for power supply and signal extraction at
the rear. At the bottom of the conversion mechanism, a cantilever 6 protruding forwardly and
obliquely projecting at the bottom is vibratably supported by a damper 7, and needle protection
portions 9, 9 for protecting the record needle 8 attached to the tip of the cantilever 6, The
bottom of the conversion mechanism 3 [111111] EndPage: 1 is formed on both sides of the
cantilever.
Since the record needle 8 is positioned somewhat lower than the tip of the needle protection unit
9, 9 at the time of normal record board tracing, the record board can be traced normally, but the
operation is erroneously recorded Since a large amount of force is applied to the needle 8 and
the record needle 8 can escape between the needle protection portions 9 and 9, the needle
protection portions 9 and 9 function to prevent damage to the record needle 8 and hence to the
record board. To A more detailed configuration of the pickup device according to the present
embodiment is shown in FIG. That is, in FIG. 4, 10 forms an outer casing of the base portion 1,
and this outer casing 10 has a box shape having a top, a bottom, and a rear open as shown in
FIG. It is usually molded of plastic together with the wings 4, 4 formed. A conductive inner
cylinder 11 having a bottom and a rear opening is fitted to the outer casing 10, and the terminal
pin 5 is formed along a guide 12 formed on the rear inner circumferential surface of the outer
casing 10, A terminal plate 13 to which 5 is attached is inserted, and the rear portion of the
casing 10 is closed by the terminal plate 13. The upper portion of the outer casing 10 is closed
by the inner cylindrical body 11 with the large hole, but is further completely closed by the
upper lid 14. The upper lid 14 is bent in an L-shape at the front to abut on the front of the casing
10 and is also used for decoration. In the inner cylindrical body 11, a support 15 is fixed at y
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level. The support 15 has projections 16.degree. 17 on the upper and lower surfaces of the front
part, and a body 18 is fixed to the rear part in the vertically penetrating conductive screw
receptacle. In the screw holder, the body 18 protrudes somewhat above the support 15, and the
circuit board 19 is attached by fitting the protrusion and the protrusion 16. A printed circuit (not
shown) is formed on one surface or both surfaces of the circuit board 19, and a part of the
printed circuit and the screw receiver are conductively coupled to each other by soldering or the
like. Further, circuit elements 20 are mounted on the circuit board 19 to form a predetermined
electric circuit together with the printed circuit, and the electric circuit is connected to the
terminal pins 5 and 5 by the connection 21.21. Electrically connected to A part of the circuit
elements 20, 20 on the circuit board 19 has a part of the terminals, that is, an input terminal
22.22 left unfixed to the circuit board 19, facing the input terminal 22.22. Through holes 23 and
24 are formed in the circuit board 19 and the support 15. The hole 24 of the support 15 is
formed in a step-like hole having a small opening on the upper surface and a large opening on
the bottom as shown in FIG.
The MLL-shaped relay terminal 25 is inserted from below into these holes 23 and 24, and the
cylindrical portion 26 formed at the upper end of the relay terminal 25 is fitted and fixed to the
circuit element 200 input terminal 22. . The vertical portion of the L-shaped relay terminal 25
approaches or contacts the upper portion of the stepped side surface of the hole 240 of the
support 15, and the L-shaped corner portion 27 is arced outward along the stepped side surface.
Curved formed. Therefore, a large elasticity is given to this corner, and a large displacement in
the vertical direction is allowed in the horizontal part of the relay terminal 25. The base unit 1 is
configured as described above, and the conversion mechanism unit that is detachably attached to
the base unit 1 next is a mechanism unit support and the hole 29 and the screw that are fitted
with the lower projections 17 of the support 15. The receptacle has a through hole 30 facing the
body 18 and a recess 31 is formed at the bottom. A fixed pole 32 made of an electret material
and constituting one pole of a capacitor is attached to the inner surface of the recess 31 and
electrically connected to a terminal pin 33 embedded in the mechanism support 28. The upper
end of the terminal pin 33 protrudes from the upper surface of the mechanism support 28 and
abuts on the horizontal portion of the relay terminal 25. Therefore, the fixed pole 32 is
electrically connected to the circuit element 200 Å power terminal 22 through the terminal pin
32 and the relay terminal 25. For stereo reproduction, as shown in FIG. 7 (the two fixed poles 32
and 32 form g 90 °), they are arranged in a letter shape and fixed to the inner surface of the
recess 31 of the mechanism support 28. A needle support 34 made of a box-like conductive
material is fixed to the mechanism support 28 so as to cover the bottom and both the front and
rear surfaces and both side surfaces of the mechanism support 28. An opening 35 is formed at
the bottom of the needle support 34 so as to face the recess 31 of the mechanism support 28,
and the opening D 35 is closed by the damper 5. Therefore, a sealed space mainly composed of
the recess 31 is formed between the mechanism support 28 and the needle support 34. The
cantilever 5 is supported by the damper 5 through the center of y. The cantilever 6 is made of a
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conductive material, and a thin wire 36 made of the same conductive material and extending
backward along the length 11111111 EndPage: 2 direction is conductively fixed to the rear
portion. The thin wire 36 has optical flexibility and tensile strength, and is electrically conductive
to the needle fixing portion 37 formed at the bottom of the needle support 34 with a
predetermined length between the cantilever 6 and the thin wire. It is fixed to For the conductive
fixing, for example, the use of the conductive adhesive 38 is effective in terms of workability.
Therefore, the cantilever 6 is supported by the damper 5 so as to be able to vibrate in a direction
perpendicular to its axis, and is supported by the thin wire 36 against the weak axial tensile force
when the damper 5 is supported. The cantilever 6 can not be displaced with respect to the tensile
force in the axial direction of the cantilever 6 which is received when the needle 8 traces the
recording board (trace distortion due to this cause can be prevented. A movable pole 35 facing
the fixed pole 32 and forming a capacitor with the fixed plate 32 is provided at the rear of the
cantilever 6. The movable pole 39 is formed by bending the rear portion of the cylindrical
cantilever 6 as shown in FIGS. 8 to 10 into a roof type whose cross section is y90 °, and the
respective flat sections forming the roof type Constitute two movable poles 39. 39 for stereo
reproduction. Each movable pole 39 ° 39 is opposed to the two fixed poles 32. 32 to form two
capacitors. The opposing state of the fixed pole 32 and the movable pole 39 in each capacitor is
in the vicinity of the cantilever 6 as shown in FIG. 9 and FIG. The extension surfaces of the poles
32 and 39 pass through the vibration center point of the cantilever 6. Therefore, the change in
the distance between the movable electrode 39 and the fixed plate 32 when the cantilever 6
vibrates is set so that the rate of change in each part is constant y. The conversion mechanism
unit 3 configured in this way is made detachable with respect to FIG. The needle protection
portions 9 and 9 are formed to project from the bottom front of the needle support 34, and a
hole 40 is provided at the rear of the bottom of the needle support 34 to face the through hole
30 of the mechanism support 28. . The screw receiver inserted into the hole 40 and the through
hole 30 of the mechanism support 28 and fixed to the support 15 is screwed into the body 18 by
the conductive screw 2 and the conversion mechanism unit 3 is Body portion 1 “auxiliary
material is in contact with the corresponding portion to obtain electrical conduction between
them, and the needle support 34 is electrically conducted to the printed circuit of the circuit
board 19 through the screw 2 The screw holder is electrically connected to the printed circuit of
the circuit board 19 by being electrically connected to the body 18. Therefore, since the movable
pole 39 provided at the rear of the cantilever 6 to form a capacitor opposite to the fixed pole 32
is electrically conducted to the needle support 34 through the thin wire 36, further The circuit is
also electrically conducted to the printed circuit of the circuit board 19, and the fixed electrode
32 is also connected to the circuit board 19 via the terminal pin 33 and the relay terminal 25.
The circuit is also connected to the circuit board 19 via the terminal pin 33 and the relay
terminal 25. Electrically conductive with the input terminal 22 of the element 20, an electrical
signal circuit is formed between the capacitor and the circuit on the circuit board 19.
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A high impedance state in the capacitor portion is converted to a low impedance state on the
circuit board 19 by the circuit element 20 or the like and is led to the terminal pins 5 and 5 for
signal extraction. Since one embodiment of the pickup device according to the present invention
is configured as described above, the performance is stable and the configuration is extremely
simplified, and external noise associated with the high impedance state in the capacitor portion is
sufficiently reduced. That is, the pickup device in the embodiment column is an active circuit in
which the impedance between the fixed pole 32 and the movable pole 39 constituting the
capacitor is constituted by, for example, the impedance conversion circuit or the amplifier circuit
by the circuit element 20 etc. It functions as a human-powered impedance, and the polarization
voltage of the electret constituting the fixed electrode 32 functions as a manual bias voltage of its
active circuit, and the change in distance between the movable electrode 39 and the fixed
electrode 32 due to the vibration of the cantilever 6 The capacitor type pickup apparatus of the
direct current type is configured such that the mechanical vibration state of the cantilever 6 is
converted into an electrical signal in the form of the change in impedance accompanying with.
Therefore, in such a pickup device, there is no factor such as thermal fluctuation of frequency
W111111EndPage: 3 in the AC system which performs frequency modulation using capacity
change as in the conventional device, etc. (The impedance of the capacitor is extremely stable
thermally. Therefore, extremely stable performance can be obtained at this point. One of the
problems with the direct current method of utilizing impedance change is that moisture or dust
intrudes between the electrodes of the capacitor to change the impedance, but the fixed electrode
32 and the movable electrode forming the capacitor as described above Since 39 is housed in a
closed space mainly composed of the recess 31 of the bottom of the needle support 34 and the
bottom of the mechanism support 28 closed by the damper 5, moisture and dust are hardly
intruded. Can be completely prevented. Further, the lower limit of the pass band of the signal
frequency in the active circuit matured on the circuit board 19 is determined by the capacity and
impedance of the input circuit, and the area of the movable electrode can be made sufficiently
wide for weight reduction of the movable body mass. In the case of transducers for pickup
applications where capacitance is as small as at most 1 pF and only 2.5 pF can be obtained in the
input circuit including other stray capacitances, the lower limit of the passband is, for example,
10 Hz. In order to reduce the frequency to f, f is a lower limit frequency (Hz), C is a capacity, and
2 is an extremely high impedance of about 1010 Ω or more as calculated from the impedance
00 equation.
The impedance inserted in parallel with the capacitor formed of the fixed electrode 32 and the
movable electrode 39 between the input terminals of the active circuit in such a point, for
example, the impedance of the fixed electrode 32 and the circuit element 20 The human body
impedance is regulated by the insulation resistance exhibited by the structure supporting body
28 which is in contact with the terminal pin 33 and the relay terminal 25 electrically connected
to the input terminal 22, and the fixed electrode 32 and the movable electrode It is required that
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at least one of the conductive paths for conducting 39 and the active circuit be provided in a
non-contact state with the low insulation resistance structure. To this end, the mechanism
support 28 in which the terminal pin 32 is embedded and the support 15 which is possible when
the relay terminal 25 comes into contact with Teflon (insulation resistance 1018 to 20 Ω-α or
less same) (brand name [111111] Materials having very high insulation resistance such as
polyphenylene oxide (1016 Ω-cIrL), polycarbonate (1018 Ω-crIL), polyethylene (1018 Ω- 鑞),
polyethylene (1016 Ω-Crn) are used. Further, since the circuit board 19 easily absorbs moisture
from the upper end face in the manufacturing process, and the insulation resistance is
considerably low such as about 10 @ 7 .OMEGA. Due to the surface treatment agent, as described
above (the circuit element 200 is connected to the circuit board 19). The manual impedance of
the active circuit is obtained by connecting the input terminal 22 and the relay terminal 25
without fixing and connecting the hole 23 provided in the circuit board 19 with the circuit board
19 in a non-contact manner. Maintained in high impedance state. Although in practice the human
impedance is lower than the insulation resistance of the structure itself because some moisture
remains on the surface of the structure, the pickup device of the above structure manufactured
by the inventors et al. Has an input of 1010 Ω to 10 11 Ω. The impedance can be obtained, and
the lower limit of the passband of the signal frequency in the active circuit can be 10 Hz or less,
and in the direct current method, the input impedance in the input circuit of the active circuit, ie,
the fixed electrode 32 and the movable electrode There is a problem in that the external
induction noise can be easily picked up and the S / N ratio is lowered because the impedance of
the capacitor portion which is formed by V. 39 and its conductive path is extremely high. In this
respect, the capacitor portion and the like are first covered with the needle support 34 made of a
conductive material and the same in the upper direction (the inner cylinder 11 and the upper lid
14 made of a conductive material are covered y Because it is housed in a box-like body made
entirely of a conductive material, externally induced noise is shielded by setting a predetermined
circuit portion on the circuit board 19 on which the needle support 34 is conductive to the
ground potential. can do.
Further, the signal in the high impedance state in the input circuit such as the capacitor unit is
subjected to impedance conversion by the active circuit on the circuit board 19 by the circuit
element 20 etc. to convert it into a signal in the low impedance state. External induced noise
intrusion at the terminal pin 5 can be almost eliminated. In the embodiment of the present
invention, a conversion mechanism for converting mechanical vibration into an electric signal is
also a novel and effective mechanism to enable high-fidelity electro-mechanical conversion. That
is, the movable electrode 39 which forms a condenser [111111] EndPage: 4 sensor facing the
fixed electrode 32 is separately provided and is not coupled to the cantilever 6 via an armature
or the like to vibrate, but the cantilever Since the rear portion of 6 is formed integrally with the
cantilever 6, no new weight is added and the movable electrode 39 can be made lightweight, so
that the weight of the mechanical vibration part is reduced and the high frequency band
Vibration characteristics are improved. For example, in an actual production example, a record
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disc recording signal of about 40 kHz can be reproduced. Further, the movable electrode 39 can
be vibrated almost in unison with the vibration of the cantilever 6 without being affected by the
vibration such as the natural vibration of the inclusion generated when the armature or the like
is interposed, and the recording disk recording signal SN Hira (Can be played. Further, the two
movable electrodes 39.degree. 39 opposed to the two fixed electrodes 32. 32 to form two
capacitors for stereo reproduction are integrally formed by bending in a roof shape as described
above. Be done. Therefore, it is extremely easy to arrange and maintain an optimal angular state
for reproducing a stereo signal, as compared to the case where the two movable electrodes 39
are arranged individually. Such a configuration can be realized by using both of the two movable
electrodes 39.degree. 39 at the ground potential, and by using at the ground potential, the
conductive path from the movable electrodes 39. 39 can be obtained. The formation can be
achieved with a very simple construction which conductively secures the wire 36 to the needle
carrier 34. As described above in detail, the present invention provides a direct-current capacitor
type pickup device having a simple configuration, stable performance, and a high SN ratio. The
present invention is not limited to the above-described embodiment, and can be variously
modified and implemented within the scope of the present invention.
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