JPS6239485B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tone arm feeding device for a so-called electronically controlled record player in which the tone arm provided in the record player is fed by a drive motor such as a linear motor. The present invention relates to a feeding device in which a speed feedback servo is applied to a drive motor that performs a feeding operation to damp low-frequency resonance of a tone arm and perform speed servo.

In general, the tone arm installed in a record player is the main factor that determines the bass characteristics of the record player's playback characteristics, and is also an important factor in applying appropriate stylus pressure to the pick-up cartridge and tracing the sound groove correctly. It is one component. For example, the bass reproduction limit frequency of a pickup is 4Hz due to the resonance characteristics of the tonearm.
It is determined by the arm resonance frequency of ~15Hz. Also, record discs usually have eccentricity or warpage, and extra stylus pressure is required for the tonearm to follow such eccentricity or warpage. Depends on impedance.

Incidentally, normally, a tone arm often exhibits sharp resonance characteristics at the arm resonance frequency, and in terms of reproduction characteristics, it is desirable to damp the resonance to make the characteristics flat. Conventionally, in electronically controlled record players, speed proportional servo control is applied to the drive means for driving the tone arm, thereby damping the resonance of the tone arm near the arm resonance frequency. Efforts are being made to suppress resonance and improve characteristics. However, in order to sufficiently suppress the above-mentioned resonance, if the servo gain of the speed proportional servo control is increased, the tone arm will be moved by the sound groove of the record disc during performance, or by the lead-out groove of the record disc. Due to relatively fast movement of the tone arm, a force in the direction opposite to the direction of groove movement is applied to the tip of the reproduction stylus, similar to when the horizontal sensitivity is reduced. The generation of such force deteriorates the sound quality during performance, and causes various problems such as the inability to trace the lead-out groove with the playback stylus especially if the stylus pressure is light during lead-out.

In view of the above-mentioned problems, an object of the present invention is to provide a record player that can sufficiently damp the resonance of the tone arm near the arm resonance frequency to obtain flat characteristics and realize good playback characteristics. It is something to do. Another object of the present invention is to equivalently prevent deterioration of horizontal sensitivity during performance or derivation, so that the tone groove or derivation groove can be correctly traced even with a light stylus pressure.
Furthermore, another object of the present invention is to prevent deterioration of reproduction characteristics due to eccentricity, warpage, etc. of a record disc. Furthermore, another object of the present invention is to
The purpose is to dampen the resonance of the tone arm. Another object of the present invention is to enable the tone arm to be accurately moved to a desired position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings showing an embodiment of an electronically controlled record player constructed by applying the present invention.

As shown in the block diagram of FIG. 1, the electronically controlled record player in this embodiment is program-controlled by a system control circuit (hereinafter simply referred to as system controller) 11 having a program control function using a microprocessor or the like.
It includes a horizontal control system and a vertical control system for the tone arm 100, and includes a horizontal drive motor 40 in the horizontal control system.
The vertical drive motor 50 in the vertical control system performs vertical drive operations such as up and down operations of the tone arm 100. It is configured as follows.

A horizontal drive control circuit 20 that supplies a drive current to the horizontal drive motor 40 is program-controlled by a horizontal control signal from the system controller 11, and controls the horizontal drive motor so as to move the tone arm 100 to a desired horizontal position. The horizontal drive motor 40 is controlled by a speed detection signal from a horizontal speed detector 60 that detects the horizontal movement speed of the tone arm 100. speed feedback control is performed. Furthermore, the horizontal drive control circuit 2
0 is the inside hose cancel circuit 15 during the performance operation by the control signal from the system controller 11.
The IFC signal is supplied from the
The horizontal drive motor 40 generates the signal according to the signal. Further, a vertical drive control circuit 30 that supplies a drive current to the vertical drive motor 50 is program-controlled by a horizontal control signal from the system controller 11, and is configured to move the tone arm 100 to a desired vertical position. In addition to controlling the drive motor 50, the speed feedback control of the vertical drive motor 50 is performed based on a speed detection signal from a vertical speed detector 70 that detects the vertical movement speed of the tone arm 100. Further, the vertical drive motor 50 is supplied with a stylus pressure signal from the stylus pressure application circuit 17 during performance operation in response to a control signal from the system controller 11, and generates a force to apply stylus pressure in accordance with this stylus pressure signal. is generated by the vertical drive motor 50. The horizontal and vertical operating positions of the tone arm 100 driven and operated by the horizontal drive motor 40 and the vertical drive motor 50 are determined by the horizontal position detector 80 and the vertical position detector 9.
Detected by 0. Each of the above position detectors 80,
Each position detection signal from 90 is sent to the system controller 11.
is supplied as a data signal to This system controller 11 is pre-installed with control programs for various operation modes of the record player, and controls predetermined program operations selected according to the mode command signal from the operation mode setter 13 to Each position detection signal from the vertical position detector 90 is processed as a data signal, and various control signals are output.

The horizontal drive control circuit 20 has a specific configuration, for example, as shown in FIG. Position feedback control according to the position detection signal from the horizontal position detector 80 is performed on the tone arm 100 that is horizontally operated by the horizontal drive motor 40.
That is, in FIG. 2, the horizontal drive control circuit 2
0 converts the control signal from the system controller 11 into an analog signal and controls the tone arm 1 by position feedback control.
A digital-to-analog converter DA that generates a position target signal indicating the target stop position of 00, and a position feedback control according to the position target signal and speed feedback control according to the speed detection signal from the horizontal speed detector 60. a servo amplifier AMP _S , and an output amplifier AMP _D that supplies drive current to the horizontal drive motor 40.
and the above servo amplifier AMP _S and output amplifier AMP _D
and an amplitude limiter LMT provided between. The servo amplifier AMP _S has its positive input terminal T _S1 connected to the detection coil 6 of the horizontal speed detector 60.
4, and its negative input terminal T _S2 is grounded through a resistor R ₁ having a resistance value R ₁ , and its output terminal T _S0 and the negative input terminal T A feedback resistor with a resistance value of _R2 between _S2 and
R ₂ is connected. The output terminal T _S0 of the servo amplifier AMP _S is connected to a resistor with a resistance value of _R3 .
Positive input terminal T _D1 of output amplifier AMP _D via R ₃
It is connected to the. The above output amplifier AMP _D has its positive input terminal T _D1 connected to each diode for amplitude limiting.
Amplitude limiter consisting of D ₁ and D ₂ connected in parallel in opposite directions
It is grounded via the LMT, and its negative input terminal T _D2 is grounded via a resistor R _S having a resistance value R _S , and its output terminal T _D0 and the negative input terminal T A drive coil 44 of the horizontal drive motor 40 is connected between D2 and _D2 .

The negative side input terminal T _S2 of the servo amplifier AMP _S receives a position target signal obtained by converting the control signal from the system controller 11 into an analog signal by the digital-to-analog converter AD, and a position target signal from the inside hose cancel circuit 15. IFC signals are supplied via resistors R ₅ and R ₆ , respectively.

In the horizontal drive control circuit 20 having such a configuration, the voltage of the speed detection signal proportional to the moving speed of the tone arm 100 obtained by the horizontal speed detector 60 is set as _eio , and each diode D of the amplitude limiter LMT is set as eio. ₁ and D ₂ are V _D and the drive current supplied from the output amplifier AMP _D to the drive coil 44 of the horizontal drive motor 40 is i, then the amplification degree A _S of the servo amplifier AMP _S is A Since _S = R ₂ /R ₁ , the voltage at the positive input terminal T _S1 of the output amplifier AMP _D is the limited voltage V _P by the amplitude limiter LMT, that is, each diode D ₁ , D _{2 .} A driving current i of i=R ₂ /R ₁ ·e _io /R ₃ is supplied until the forward voltage V _D exceeds the forward voltage V _D
In this case, a drive current i of i=V _D /R ₃ is supplied.

In such a horizontal drive control circuit 20,
A tone arm 100 that can obtain a speed detection signal within the amplitude limit range by the amplitude limiter LMT.
For the horizontal movement speed of Control is performed to reduce the torque of the horizontal drive motor 40 by limiting the voltage at the negative input terminal T _D2 of the output amplifier AMP _D by the amplitude limiter LMT, thereby sufficiently preventing the tone arm 100 from eccentricity and warpage. can be made to follow.

The above amplitude limiter LMT is connected to a feedback resistor connected to the servo amplifier AMP _S , as shown in Figure 3.
It may be connected in parallel to _R2 . In the horizontal drive control circuit 20A shown in FIG. 3, a drive voltage e _put as shown in FIG. 4 is applied to the drive coil 44 of the horizontal drive motor 40, and the amplitude limiter LMT
For a speed detection signal equal to or higher than the voltage V _P determined by , a drive voltage e _put of e _put ≈V _D +e _io is applied to the drive coil 44 . In addition, the above amplitude limiter LMT
As shown in FIG. 5, the point of change in the speed feedback control characteristic, that is, the control voltage V _P is determined by the resistors R ₃ and R ₄ connected in series between the output terminal T _S0 of the servo amplifier AMP _S and the ground. By supplying the voltage obtained at the midpoint of the connection of each resistor R ₃ , R ₄ of value to the positive input terminal T _D1 of the output amplifier AMP _D , V _P =R ₄ /R ₃ +R ₄ - It can be set to any voltage that can be expressed by the formula V _D. In the horizontal drive control circuit 20B shown in FIG. 5, for the speed detection signal of the signal voltage e _io corresponding to the predetermined voltage V _P or more, i=V _P /R _S =R ₄ /R _S・V _D /R ₃ +
The horizontal drive motor 40 is driven by a drive current i of _R4 . In addition, this horizontal drive control circuit 2
At 0B, switch SW is applied to the amplitude limiter LMT.
are connected in series, and by closing the switch SW during the performance operation of the record player, a change point V _P is given to the speed feedback control characteristic by the operation of the amplitude limiter LMT, and the tone arm 1
00's low frequency resonance and speed servo, and by keeping the switch SW open when the record player is not playing, the tone arm 10 has excellent responsiveness due to speed proportional feedback control.
0 lead-in or lead-out operation is performed.

In addition, as in the implementation of the horizontal drive control circuit 20C shown in FIG.
Zener diodes ZD ₁ and ZD ₂ may be connected in series to D ₁ and D ₂ , respectively, and the limiting voltage _VP may be determined based on each Zener voltage V _Z.

In the embodiments of the water drive control circuits 20, 20A, 20B, and 20C shown in FIGS. 2 to 6 above, common components are given the same reference numerals in each figure.

Next, the mechanical configuration of this example will be explained in the seventh section.
This will be explained using FIGS. 11 to 11. First, the tone arm 100 is attached via a support mechanism 120 to the upper end of a center shaft 102 that is rotatably and upright supported by an arm base 101 fixed to the top panel 131 of the player body 130. . The tone arm 100 is arranged in a vertical direction (vertical direction) with axes that are orthogonal to each other, with the axis of the support shaft of the support mechanism 120 being a horizontal axis, and the axis of the center shaft 102 being a vertical axis. and horizontally pivotably supported. A cartridge shell 103 provided at the tip of the tone arm 100 includes a turntable 13.
A pick-up cartridge 105 is attached with a playback needle 104 that traces the sound groove of a record disc 133 placed on the top of the record disc 133. Further, a balance weight 106 for balance adjustment is attached to the rear end side of the tone arm 100 so as to be movable and adjustable along the axial direction of the tone arm 100.

A horizontal drive motor 40 for horizontally operating the tone arm 100 includes a magnetic circuit section 43 having a permanent magnet 41 curved in an arc shape around the vertical axis, and a drive coil 44 wound around a bobbin 45. The magnetic circuit section 43 is fixed to the arm base 101 via a fixed arm 141, and the bobbin 45 around which the drive coil 44 is wound is connected to the tone arm 100 via a rotating arm 142. It is attached to a center shaft 102 that rotates integrally horizontally. The magnetic circuit section 43 includes a frame-shaped yoke 42 having two horizontal rods 42a and 42b curved into an arc shape similar to the permanent magnet 41, and the above-mentioned It is formed by fixing a permanent magnet 41. The permanent magnet 41 is magnetized in its upper and lower thickness directions, that is, in the vertical direction. The yoke 42 forms a closed magnetic path through which the magnetic flux generated from the permanent magnet 41 passes. Further, a predetermined interval is provided between the other horizontal rod 42b of the yoke 42 and the permanent magnet 41, and the bobbin 45 around which the drive coil 44 is wound is attached to the horizontal rod 42b.
b, and is arranged so as to be freely rotatable in the horizontal direction along the horizontal rod 42b. A drive current from the horizontal drive control circuit 20 is passed through the drive coil 44 wound around the bobbin 45 in a direction perpendicular to the direction of the magnetic flux generated from the permanent magnet 41 .

The horizontal drive motor 40 having such a configuration has a direction (sixth direction) of the drive current flowing through the drive coil 44.
Depending on the direction of the arrow a or the direction of the arrow in the figure),
A driving force in the direction of arrow b or arrow in FIG. 6 is generated according to Fleming's left-hand rule, and by applying this driving force to the center shaft 102, the tone arm 100 is moved in the lead-in direction or the lead-out direction. Can be rotated.

The vertical drive motor 50 for vertically operating the tone arm 100 is, in principle, the same as the horizontal drive motor 40 described above, but is arranged vertically. That is, in this example, the eighth
As shown in the figure, a yoke member 52A having an E-shaped longitudinal section
and an I-shaped yoke member 52B, and a pair of permanent magnets 51A and 51B that face each other are fixed to a yoke 52 that faces each other with a vertical rod 52b at the center of the E-shaped yoke member 52A. Part 53
and a drive coil 54 wound around a bobbin 55 which is fitted around the vertical rod 52b and is relatively movable along the vertical rod 52b.
is connected to the center shaft 10 via the rotating arm 143.
2, and a bobbin 55 around which the drive coil 54 is wound is arranged and fixed at the center of a mounting frame 144 provided at the rear end of the tone arm 100. The permanent magnets 51A, 51B forming the magnetic circuit section 53 and the vertical rods 52a, 52b, 52c of the yoke 52 are curved in an arc shape with the horizontal axis of the support mechanism 120 as the center. . In addition, each of the above permanent magnets 51A, 51
B is magnetized in its left and right thickness direction, that is, in the horizontal direction, so that the horizontal magnetic flux generated therefrom flows through a closed magnetic path formed via the moke 52. Furthermore, a drive current from the vertical drive control circuit 30 is passed through the drive coil 54 in a direction perpendicular to the direction of magnetic flux generated by the permanent magnets 51A, 51B.

The vertical drive motor 50 having such a configuration generates a driving force in the direction of the arrow c or in the direction of the arrow in FIG.
By applying this force, the tone arm 100 can be rotated in the down direction or up direction.

A vertical speed detector 70 for detecting the vertical operation speed of the tone arm 100 driven and operated by the vertical drive motor 50
A generator is constituted by a magnetic circuit section 73 and a detection coil 74, which have the same structure in principle as that of the tone arm 100. The magnetic circuit section 73 connects to the center shaft 10 via the rotating arm 144.
2, and the magnetic circuit section 73 is arranged and fixed at the center of a mounting frame 145 provided on the tone arm 100. This vertical speed detector 70 is configured such that when the tone arm 100 pivots in the vertical direction, the detection coil 74 moves in the vertical direction integrally with the tone arm 100 and moves relative to the magnetic circuit section 73. Then, the detection coil 74 generates a speed detection signal with a signal level corresponding to the moving speed. A detection signal obtained from the vertical speed detector 70 is supplied to the vertical drive control circuit 30 and used for speed feedback control of the vertical drive motor 50.

Further, a vertical position detector 90 for detecting the vertical operation position of the tone arm 100 driven and operated by the vertical drive motor 50, that is, arm down, arm up, etc., includes a detection coil 94 and a detection coil 94. It is composed of a rod-shaped dust core 92 that can be put in and taken out relatively freely. The detection coil 94 is wound around a cylindrical bobbin 95 on the tone arm 1.
00, and the dust core 92 is mounted upright on the rotating arm 144 and placed in a position below the detection coil 94.

The vertical position detector 90 having such a configuration has a detection coil 9 that corresponds to the vertical operation of the tone arm 100.
The vertical operation position of the tone arm 100 can be detected by the state of change in the inductance of the detection coil 94, which changes according to the relative position between the tone arm 4 and the dust core 92. The vertical position detector 90
The vertical position detection signal obtained from the vertical position detection signal is used for position feedback control of the vertical drive motor 50.

Further, a horizontal speed detector 60 for detecting the horizontal operation speed of the tone arm 100 driven and operated by the horizontal drive motor 40 includes a magnetic circuit section 63 and a detection coil 64 having the same structure in principle as the horizontal drive motor. The magnetic circuit section 63 is fixed to the arm base 101 via the fixed arm 146, and the detection coil 74 is fixed to the arm base 101 via the fixed arm 146.
is connected to the center shaft 10 via the rotating arm 147.
It is attached to 2. This horizontal speed detector 60
When the tone arm 100 pivots in the horizontal direction, the detection coil 64 moves in the horizontal direction integrally with the tone arm 100 and moves relative to the magnetic circuit section 63. The detection coil 64 generates a speed detection signal with a signal level corresponding to the signal level.

The speed detection signal obtained from the horizontal speed detector 60 is supplied to the horizontal drive control circuit 20 and used for speed feedback control of the horizontal drive motor 40.

Furthermore, the horizontal position detector 80 for detecting the horizontal operation position of the tone arm 100 is a ninth
As shown in the figure, a movable slit plate 81 is attached to the center shaft 102 via a mounting plate 148.
, a fixed slit plate 82 fixed to the arm base 101 and arranged close to and parallel to the movable slit plate 81, and three pairs of light emitting elements 83A disposed opposite to each other with the slit plates 81 and 82 interposed therebetween. ,8
3B, 83C and light receiving elements 84A, 84B, 8
It is composed of 4C. The movable slit plate 81 is formed into a substantially fan shape centered on the vertical axis of the center shaft 102, and a large number of slits 85 are formed at predetermined intervals and pitches along the periphery of the movable slit plate 81, centered on the vertical axis. The elongated holes 86 are arranged in a circular arc shape and have a circular arc shape centered on the vertical axis and a wedge-shaped one end edge 86a. Further, the fixed slit plate 82 is connected to the slit 8 of the movable slit plate 81.
Several slits 87 are formed in two areas opposite to each other with the same spacing and pitch as the slits 85.
A and 87B are arranged in an arc shape centered on the vertical axis, and slits 88 are formed at positions corresponding to the elongated holes 86 of the movable slit plate 81. Note that the slits 8 formed in two areas of the fixed slit plate 82
7A and the slit 87B are approximately the slit interval λ with respect to the slit 85 of the movable slit plate 81.
They are arranged with a relative shift of 1/4. Three pairs of light emitting elements 83A, 83 facing each other with the movable slit plate 81 and fixed slit plate 82 in between.
B, 83C and light receiving elements 84A, 84B, 84
C denotes mounting surfaces 89A and 89B that are formed parallel to the holder 89 fixed to the arm base 101 via the mounting arm 149 with a predetermined gap.
Each slit 8 of the fixed slit plate 82 is arranged in
They are arranged at positions corresponding to 7A, 87B, and 88.

In the horizontal position detector 80 having such a configuration, when the tone arm 100 is operated horizontally, the movable slit plate 81 horizontally rotates together with the center shaft 102, and the slit 85 and the elongated hole 86 of the movable slit plate 81 are aligned with each other. Each slit 87 of the fixed slit plate 82
By changing the relative positional relationship with A, 87B, 88, each light receiving element 84A, 84B, 84C
The following position detection signal can be obtained from That is, the light receiving element 84C arranged corresponding to the slit 88 of the fixed slit plate 82 is
The slit 88 is a long hole 86 of the movable slit plate 81.
The light from the light emitting element 83C is received during the period overlapping with the above period, and is used as origin information indicating that the tone arm 100 is at the armrest 134 position, that is, the starting position of the horizontal operation of the tone arm 100. Further, the light receiving elements 84A, 84B arranged corresponding to the respective slits 87A, 87B of the fixed slit plate 82 are arranged according to the relative positional relationship between the respective slits 87A, 87B and the slit 85 of the movable slit plate 81. It intermittently receives light from each light emitting element 83A, 83B and outputs a two-phase position detection signal. Since the slits 87A and 87B provided on the fixed slit plate 82 are shifted by 1/4λ, the two-phase position detection signals obtained from the respective light receiving elements 84A and 84B are detected by the horizontal operation of the tone arm 100. It has a phase difference of ±1/4λ, that is, ±90° depending on the direction, and with this phase difference, the tone arm 100
This shows information on the operating direction, ie lead-in and lead-out. In addition, the repetition period of the two-phase position detection signal becomes shorter as the horizontal movement speed of the tone arm 100 suddenly increases near the end where the sound groove of the record disc 133 disappears. Information on the lead-out position is shown by changes in the cycle. Furthermore, the two-phase position detection signal is transmitted to the tone arm 1.
The signal level changes sequentially by the relative movement of each slit 87A, 87B whose arrangement position is fixed with respect to the slit 88 of the fixed slit plate 82 which provides information on the start position of 00 and the slit 85 of the movable slit plate 81. At each point of change in the signal level, information on the absolute position of the tone arm 100 in the horizontal direction with respect to the start position is shown.

In the embodiment of the configuration as described above, the system controller 1
1, when the automatic performance mode is specified and the start of operation is commanded by the operation mode setting device 13, each program control of the lead-in operation, performance operation, and lead-out operation is performed according to a predetermined program as follows. conduct.

First, in the lead-in operation, a position detection signal indicating the origin position information obtained from the light receiving element 84C of the horizontal position detector 80 and each of the light receiving elements 84A, 8 are transmitted.
Based on the two-phase position detection signal indicating the absolute current position information of the tone arm 100 with respect to the origin position obtained from 4B, the system controller 11 is at the starting position where the tone arm 100 is placed on the armrest 134. If the tone arm 100 is at the start position, a horizontal control signal is supplied to the horizontal drive control circuit 20 to immediately move the tone arm 100 in the lead-in direction. If the tone arm 100 is not at the start position, a horizontal control signal is supplied to the horizontal drive control circuit 20 to move the tone arm 100 in the lead-out direction, once return to the start position, and then move it in the lead-in direction. The system controller 11 compares the target position information indicating the read point given in advance with the absolute current position information of the tone arm 100 based on the two-phase position detection signal from the horizontal position detector 80. The horizontal drive control circuit 20 continues to drive the horizontal drive motor 40 using the horizontal control signal until the tone arm 100 reaches a predetermined lead-in point. When the tone arm 100 reaches the lead-in point, the horizontal drive control circuit 20 performs position feedback control to stop the tone arm 100 accurately at the lead-in point. Further, during the lead-in operation as described above, the system controller 11 performs vertical drive control to maintain the tone arm 100 in the up position based on the position detection signal from the vertical position detector 90. When the tone arm 100 reaches the target lead-in point, the vertical drive control signal is sent to the control circuit 30 to cancel the position feedback control and move the tone arm 100 in the down direction. It is supplied to the circuit 30.

Note that during the lead-in operation of the tone arm 100, the horizontal and vertical movement operations of the tone arm 100 are performed by the horizontal speed detector 6.
0 and each drive motor 40, 50 via the horizontal drive control circuit 20 and the vertical drive control circuit 30 based on each speed detection signal from the vertical speed detector 70.
The speed feedback control is applied to perform the lead-in operation at a constant speed, and the lead-in operation is completed by lowering the playback needle 104 attached to the tone arm 100 to a predetermined lead-in point.
In the performance operation performed following such a lead-in operation, each drive motor 40 as described above,
The position feedback control of 50 is canceled and only speed feedback control is performed, and the inside hose cancel circuit 1 is
5 and the stylus pressure application circuit 17 are activated, the horizontal drive motor 40 is supplied with a drive current that generates a force for inside hose cancellation from the horizontal drive control circuit 20, and the vertical drive motor 50
A drive current is supplied from the vertical drive control circuit 30 to provide a predetermined stylus pressure. Therefore, during the performance operation of the tone arm 100, a force that cancels the inside hose is applied to the horizontal drive motor 4.
0, a force is applied by the vertical drive motor 50 to provide a predetermined stylus pressure. Furthermore, the tone arm 100 has excellent low-frequency resonance characteristics through speed feedback control of each of the drive motors 40 and 50, and the tone arm 100 has excellent low-frequency resonance characteristics, and can suppress the sound of the record disc 133 even when the record disc 133 warps. The playing operation is performed with a braking force applied so as not to impair the tracing ability of tracing the groove with the playback needle 104.

When the playback needle 104 of the tone arm 100 traces the vicinity of the end of the tone groove on the record disc 133 by performing the above-mentioned performance operation, it is noticed that the pitch of the tone groove near the end becomes larger. As a result, the moving speed of the tone arm 100 becomes faster, and end detection is performed based on this change in moving speed, and a lead-out operation is started.
In this readout operation, the system controller 11 first detects the end by comparing the repetition period of the two-phase position detection signals from the light receiving elements 84A and 84B of the horizontal position detector 80 with a predetermined time. conduct. Immediately after detecting the end, the system controller 11 causes the vertical drive control circuit 30 to drive the vertical drive motor 50 in the upward direction using a vertical control signal, thereby performing an upward movement of the tone arm 100. After the tone arm 100 is raised, the system controller 11 controls the vertical drive control circuit 30 to maintain the tone arm 100 in the raised state based on the position detection signal from the vertical position detector 90. In addition to performing position feedback control, the horizontal drive control circuit 20 drives the horizontal drive motor 40 in accordance with the horizontal control signal to move the tone arm 100 in the lead-out direction. In this way, when the tone arm 100 is led out and approaches the armrest 134, and the elongated hole 86 of the horizontal position detector 80 overlaps with the slit 88, the tone arm 100 is horizontally driven based on the position detection signal from the light receiving element 84C. At the same time as stopping the drive of the motor 40, the position feedback control of the vertical drive motor 50 is canceled and the tone arm 100 is lowered onto the armrest 134 by the vertical drive motor 50. In this way, when the tone arm 100 is placed on the armrest 134, the system controller 11 stops the operation of each control system in response to the position detection signal from the vertical position detector 90, and performs a series of program operations. complete.

In the embodiment having the above-described configuration, for example, the horizontal drive control circuit 20 having the configuration shown in FIG.
Since the horizontal drive motor 40 is driven by B,
By keeping the switch SW open during lead-in and lead-out feeding operations of the tone arm 100, speed proportional feedback control is performed to stably feed the tone arm 100 at a predetermined speed, thereby controlling the record player. In the performance state, the switch SW is closed to give the speed feedback control characteristic a change point as shown in FIG. It is possible to obtain flat reproduction frequency characteristics without narrowing the reproduction band, and to accurately trace the sound groove with a pickup without generating unnecessary force on the tone arm 100 even in response to disturbances.

Note that it is also possible to give a change point to the speed feedback control characteristics by inserting, for example, a low-frequency cut filter into the speed feedback loop to lower the servo gain near the low-frequency resonance frequency of the tone arm.
New problems such as a phase shift caused by the low-pass cut filter may occur, and there is a possibility that the sound quality of the reproduced signal may deteriorate due to the effect of the low-pass cut filter.

In the present invention, since an amplitude limiter using a diode is disposed within the speed feedback loop, there is no adverse effect such as phase shift.

As is clear from the description of the above-mentioned embodiments, according to the present invention, a speed detection signal having a signal level corresponding to the moving speed of the tone arm is supplied to a drive motor that performs a feeding operation of the tone arm. A speed feedback control loop configured to feed back to the drive control circuit is provided, and an amplitude limiter is provided in the speed feedback control loop,
Not only is it possible to sufficiently damp the resonance near the arm resonance frequency of the tonearm without narrowing the playback band to obtain flat playback characteristics, but it also allows accurate tracing of the sound groove or lead-out groove even when picking up with light stylus force. At the same time, it is possible to prevent deterioration of the playback characteristics due to the effects of eccentricity, warpage, etc. of the record disc, and the intended purpose can be fully achieved.

It should be noted that the present invention is not limited to the above-described embodiments, but includes many other modifications, such as providing an amplitude limiter in the speed feedback control loop in the vertical drive control circuit. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a drive control system in an embodiment of an electronically controlled record player constructed according to the present invention. FIG. 2 is a circuit diagram showing the configuration of the horizontal drive control circuit applied to the above embodiment. FIG. 3 is a circuit diagram showing another example of the configuration of the horizontal drive circuit. FIG. 4 is a characteristic diagram for explaining the operation of the horizontal drive control circuit shown in FIG. 3 above. FIGS. 5 and 6 are circuit diagrams showing still other configuration examples of the horizontal drive control circuit. FIG. 7 is a front view of the tone arm portion in the above embodiment. FIG. 8 is a plan view of the tone arm as well. FIG. 9 is a perspective view of the appearance of the tone arm portion. FIG. 10 is a longitudinal sectional view of a vertical drive motor portion applied to the above embodiment.
FIG. 11 is a plan view of the horizontal position detector portion applied to the above embodiment. 11... Cisco, 20, 20A, 20B, 2
0C...Horizontal drive control circuit, 30...Vertical drive control circuit, 40...Horizontal drive motor, 44...Drive coil, 50...Vertical drive motor, 60...Horizontal speed detector, 64...Detection coil, 70... Vertical speed detector, 100... Tone arm, AMP _S ...
...Servo amplifier, AMP _D ...Output amplifier, LMT
... Amplitude limiter, D ₁ , D ₂ ... Diode, ZD ₁ ,
ZD ₂ ... Zener diode.

Claims (1)

[Scope of Claims] 1. Speed feedback in which a speed detection signal having a signal level corresponding to the moving speed of the tone arm is fed back to a drive control circuit that supplies a drive current to a drive motor that performs a feeding operation of the tone arm. A tone arm feeding device comprising a control loop, and an amplitude limiter provided in the speed feedback control loop. 2. A speed feedback control loop configured to feed back a speed detection signal at a signal level corresponding to the moving speed of the tone arm to a drive control circuit that supplies a drive current to a drive motor that performs a feeding operation of the tone arm, An amplitude limiter and a switch are provided in the speed feedback control loop, and the amplitude limiter is operated by closing the switch means when the record player is playing, and the switch means is activated when the tone arm is lead-in or lead-out. A tone arm feeding device characterized in that the operation of the amplitude limiter is prevented by opening the circuit.