JPS6245601B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a position control device for holding a controlled object in a predetermined position. The present applicant has proposed an electronically controlled record player in which the tone arm is rotated in the horizontal and vertical directions by electromagnetic driving means, according to the invention previously filed. Therefore, first, before explaining the embodiments of the present invention, the embodiments of the invention according to the above application and the problems thereof will be explained with reference to the drawings. In FIG. 1, a tone arm 1 is provided so as to be horizontally rotatable in the directions of arrows a and b by an arm shaft 2, as is conventionally known.
A cartridge 5 that is vertically rotatable in the direction of the cartridge and has a regeneration needle 4 at its tip, and a song interval detector 37.
is provided. This tone arm 1 is provided with a horizontal drive motor 6, a vertical drive motor 7, a horizontal position detector 8, and a vertical position detector 26. The horizontal drive motor 6 is composed of a rotor consisting of a coil 10 wound around a bobbin 9, and a stator consisting of a yoke 11 and a magnet 12. The bobbin 9 is attached to the tip of a support rod 13 that is integrally provided on the arm shaft 2. yoke 1
As shown in the figure, a yoke member 1 has a rectangular ring shape and is curved in an arc shape centered on an arm shaft 2, and is fixedly supported on the player by appropriate means. A magnet 12 magnetized in the thickness direction is provided on the lower part 11a of this yoke 11 by adhesion or the like, and the upper part 11
The bobbin 9 is rotatably fitted to the magnet 12 with a predetermined gap. Further, terminals 39a and 39b are led out from the coil 10. This horizontal drive motor 6 is for rotating the tone arm 1 in the directions of arrows a and b. That is, the terminal 39 is connected to the coil 10 from the horizontal drive circuit 40.
When a driving voltage is applied through a and 39b, a current that interlinks with the magnetic flux of the magnet 12 flows through the coil 10, and a horizontal force acts on the coil 10. As a result, the tone arm 1 moves as shown by the arrow a.
It is configured to rotate at a constant speed in the b direction. The vertical drive motor 7 has a coil 16 wound around a bobbin 15 attached to the rear end of the tone arm 1.
and a stator consisting of a yoke 18 and magnets 19 and 20 attached to the tip of a support rod 17 provided on the arm shaft 2. The yoke 18 is formed into a rectangular ring shape as shown in the figure, and has a guide portion 18 in the center thereof.
It has a shape in which a yoke member having a formed thereon is curved into an arc shape centered on the shaft 3. Magnets 19 and 20 are fixed to the inner surfaces of the left and right side parts 18b and 18c of this yoke 18 by adhesive or the like with the same magnetic pole faces facing each other, and the guide part 18
A bobbin 15 is rotatably fitted to magnets 19 and 20 with a predetermined gap.
Further, terminals 14a and 14b are led out from the coil 16. Incidentally, this motor 7 is connected to the tone arm 1.
This is provided to rotate the holder in the directions of arrows c and d. That is, by applying a control signal to the terminals 14a and 14b, a current that interlinks with the magnetic flux of the magnets 19 and 20 flows through the coil 16, and a vertical force acts on the coil 16. This allows the tone arm 1 to be rotated at a predetermined speed in the directions of arrows c and d. A horizontal position detector 8 is provided on the arm shaft 2,
Slit plate 2 that rotates integrally with this arm shaft 2
2, a slit plate 21 fixed below this slit plate 22 by appropriate means, and light emitting elements 23a, 23b and light receiving elements fixedly supported by appropriate means above and below these slit plates 21, 22, facing each other. It is composed of 24a and 24b. A large number of slits 25 are arranged on the slit plate 22 along an arc centered on the arm axis 2. As shown in FIG. 2, the slit plate 21 is
A first slit portion 31a and a second slit portion 31b are provided at positions facing the slit 25, respectively. The slit pitch of the first slit portion 31a and the pitch of the second slit are shifted from each other by, for example, 1/4. According to the above configuration, when the tone arm 1 rotates in the directions of the arrows a and b, the slit plate 22 rotates accordingly, and as a result, the light receiving elements 24a and 24b output two signals whose phases are shifted by π/4 from each other. Sinusoidal signals are obtained and these sinusoidal signals are applied to the detection circuit 32. In this case, depending on the rotating direction of the two sine wave signal tone arms 1 in the a direction or the b direction, one sine wave signal will lead the other sine wave signal in phase by π/4. The detection circuit 32 converts each of the sine wave signals into pulse signals, outputs the number of pulse signals corresponding to the rotation angle of the tone arm 1 as a horizontal position detection pulse signal, and detects the phase difference. The rotation direction is determined by the rotation direction, and a direction determination signal is output. The vertical position detector 26 is a rod-shaped magnet 28 provided on the lower surface of the support portion 27 of the tone arm 1.
, a core 29 provided on the support rod 17 and disposed close to the magnet 28, and this core 29.
9 and a coil 30 wound around the coil 30. The coil 30 is connected as a tuning coil for an oscillator (not shown) via terminals 33a and 33b. According to the above configuration, when the tone arm 1 rotates in the directions of arrows c and d, the area in which the magnet 28 and the core 29 face each other changes accordingly, so that the inductance of the coil 30 changes. Therefore, a vertical position detection signal having an oscillation frequency corresponding to the rotation angle of the tone arm 1 in the vertical direction is obtained from the oscillator. Note that this detection signal is used to control the vertical drive motor 7. The track interval detector 37 may be of a conventionally known type, and detects the track interval based on the difference between the amount of light reflected from the sound groove surface of the record and the amount of light reflected from the feed groove (between tracks) surface, for example. Something like this is used. This inter-music detection signal is applied to the system control circuit 38. In this player, the tone arm 1 is rotated by the horizontal drive motor 6 from the rest position to a predetermined position above the record, and at that position, the tone arm 1 is rotated by applying the horizontal position servo to the horizontal drive motor 6. is held in that position, and then the vertical drive motor 7 is turned on while the horizontal position servo is applied.
, the tone arm 1 is lowered, the needle 4 is lowered onto the tone groove of the record, and the performance is started. After the performance is over, the vertical drive motor 7 raises the tone arm 1, and then the horizontal drive motor 6 rotates the tone arm 1 to the next desired position. In addition, this player is configured to play records in a preprogrammed order, and the above-mentioned operation is performed by pressing a start button (not shown) provided on the player, which causes the system controller circuit 3 to play.
The program is automatically repeated in the order of the program based on the instructions in 8. Next, the horizontal position detection pulse signal and direction determination signal obtained from the detection circuit 32 are applied to a counter 34. The counter 34 counts up the pulse signal according to the determination signal when the arm 1 is rotated in the direction of the arrow a, and counts up the pulse signal according to the determination signal when the arm 1 is rotated in the direction of the arrow b. , is configured to count down the pulse signal. On the other hand, when the inter-track detector 37 detects that the arm 1 has been rotated to a predetermined position, a rotation stop command signal is sent from the system control circuit 38 to the counter 34 and the horizontal drive circuit 4.
0, thereby causing the counter 34 to start counting. counter 3
The count output of 4 is converted into an analog voltage by the D/A converter 35 and applied to the horizontal control circuit 36. The horizontal control circuit 36 outputs a control signal in response to the analog voltage, and this control signal is applied to the coil 10 of the motor 6. The above detection circuit 32, counter 34, D/A converter 35, motor 6, and horizontal position detector 8 constitute the horizontal position servo system. Next, the operation of the horizontal position servo system will be explained. First, by pressing the start button provided on the player, the system control circuit 38 is activated, and based on the instruction, the horizontal drive circuit 40 connects the terminal 39.
A driving voltage is applied to a and 39b. As a result, current flows through the coil 10 to drive the motor 6, and the tone arm 1 begins to rotate in the direction of arrow a from the rest position. When the cartridge 5 passes above the record with this rotation, the inter-track detector 3
7 sequentially detects the intervals between songs on the record and applies the detected signals to the system control circuit 38. When a pre-programmed song interval is detected, a rotation stop command signal is applied from the system control circuit 38 to the counter 34 and the horizontal drive circuit 40. As a result, the drive voltage applied to the coil 10 from the horizontal drive circuit 40 is cut off, and the motor 6 is stopped.
At this time, the tone arm 1 passes a predetermined stop position due to inertia. On the other hand, the counter 34 is operated by the rotation stop command signal and receives a pulse signal P as shown in FIG. 3A applied from the detection circuit 32.
Start counting. At this time, since the tone arm 1 has passed the above-mentioned predetermined position and is still rotating in the direction of the arrow a, the detection circuit 32 outputs "1" (high height) indicating rotation in the direction a as shown in FIG. 3B. A discrimination signal S of the level) is obtained. Therefore counter 3
4 first generates a pulse signal P based on this discrimination signal S.
count up. The count output at this time is converted by the D/A converter 35 into a rising analog voltage E as shown in FIG.
Added to 6. Based on this rising voltage E, the horizontal control circuit 36 applies a voltage V to the coil 10 so that the tone arm 1 rotates in the direction of arrow b. This voltage V causes the tone arm 1 to pass from a predetermined position to a point where the counter 34 has counted, for example, five pulse signals P, and then is rotated in the direction of arrow b. As a result, the tone arm 1 approaches the predetermined position, but due to inertia, it passes through that position again. While this rotation is being performed, the discrimination signal is "0" (low level), so the counter 3
4 counts down the pulse signal P from the above count value. As a result, a voltage lower than that at the start of counting is output from the D/A converter 35 to the horizontal control circuit 3.
2, thereby applying a voltage to the coil 10 to brake the rotation of the tone arm 1 in the b direction. As a result, the tone arm 1 passes from a predetermined position to a point where the counter 34 has counted, for example, seven pulse signals P, and then is rotated again in the direction a, and the discrimination signal becomes "1" again. Due to this rotation, the tone arm 1 also passes through a predetermined position. As a result, the same operation as described above is performed, and the tone arm 1 is braked in the direction b from the position where it has passed. As described above, the tone arm 1 is alternately rotated in directions a and b, and each time it passes through the target position due to inertia, but each time the above-mentioned horizontal position servo operation is repeated, the passing distance becomes smaller. Finally, it is stopped and held at the target position. Even in this held state, the tone arm 1 still has a horizontal position servo, so that even if the tone arm 1 is swung by an external force, it is returned to its original position by the control operation described above. Next, when the motor 7 is driven in this state, the tone arm 1 descends with the horizontal position servo applied, and when the playback needle 4 reaches the top of the record, the servo is released and the performance begins. . After the performance is finished, the tone arm 1 is raised by the motor 7 and then rotated in the direction a or b by applying a drive voltage from the horizontal drive circuit 40 to the motor 6, and then programmed. When it is rotated to the position of the new song, the driving voltage is cut off, and the aforementioned servo operation is performed to stop it at a predetermined position. However, the following problems occur regarding the above-mentioned horizontal position servo. In this position servo, in order to stop the tone arm 1 at the target position,
The count output of the counter 34 is converted into an analog voltage E by a D/A converter 35, and the motor 6 is controlled based on this voltage E. Therefore, the count value of the counter 34 indicates the difference between the target position and the current position of the tone arm 1. Since the tone arm 1 is controlled by a position servo, it moves only in the vicinity of the target position during normal operation. However, if the tone arm 1 is stopped at the target position, for example,
If the tone arm 1 is moved by a large width due to accidental contact with a hand or the like, the counter 34 must be moved by the large width in order to return the tone arm 1 from the moved position to the target position using the position servo. The distance traveled must be counted. Considering such a case, the counter 34 needs to have a counting ability that covers the entire movable range of the tone arm 1, and the D/
The A converter 35 needs to have a large number of bits. However, D/A with a large number of bits
The problem with converters is that they are expensive. In addition, the drive voltage V (proportional to the converted voltage E) for applying position servo to the motor 6 is, for example, 0 at the target position.
Volt, positive voltage until the target position, and negative voltage after passing the target position. In this case, when the tone arm 1 swings far away from the target position, a high drive voltage proportional to the swing is required to quickly return it from that position to the target position. However, since the number of bits of the D/A converter 35 described above is limited, the absolute value of the output voltage E of the D/A converter 35, which is proportional to the deviation of the tone arm 1 from the target position, does not exceed a certain voltage. . Therefore, when the tone arm 1 moves beyond a certain distance from the target position, it is necessary to maintain the above-mentioned constant voltage. The present invention improves the circuit of the counter 34 in order to solve the above-mentioned problems, and an embodiment in which the present invention is applied to the record player system described above will be described below with reference to the drawings. In FIG. 1, for example, the counter 34 has 10 bits, which is sufficient to cover the entire movable range of the tone arm 1, and the D/A converter 35 has 8 bits.
Bits shall be used. Further, when the input from the counter 34 is "11111111" from the upper bit, the D/A converter 35 outputs a maximum voltage of +10.
It outputs volts, and when it is "10000000" it outputs 0 volts, and when it is "00000000" it outputs the minimum voltage -10 volts. As mentioned above, when the tone arm 1 swings far from the target position, in order to quickly return it, it is sufficient to apply a constant drive voltage with a high absolute value to the motor 6; In order to obtain this, the output of the D/A converter 35 may be set to be constant at +10 volts or -10 volts. For this purpose, when the counter 34 counts 8 bits and more counts occur, that is, the count value becomes "256".
When the value exceeds 0, the input to the D/A converter 35 is held at "11111111", and when the value falls below 0, the input is held at 00000000. That is, as shown in FIG. 5, a D/A conversion output corresponding to the movement of the tone arm 1 may be obtained. In order to perform this holding, the present invention uses three counters each having four bits, as shown in FIG.
It is composed of counters 34a, 34b, 34c, AND gates 41 to 45, and OR gate 4.
A circuit configuration in which 6 to 50 and inverters 51 and 52 are connected as shown is used. In this circuit, the counter 34a is an overflow detection counter. In addition, the 8-bit input from MSB to LSB of the D/A converter 35 is input to the counter 34.
Each bit output Qb ₄ ~Qb ₁ and Qc ₄ ~Qc ₁ of b, 34c
It is determined based on the 8-bit output of . Therefore, the counters 34c and 34b change the pulse signal P from 1 to
When counting up to 256, Qb ₄ ~ Qb ₁ ~ Qc ₄
All arbitrary bit outputs (hereinafter referred to as _A ) within the 8 bits consisting of .about.Qc1 become "1", and at this time a carry output is added from the counter 34b to the counter 34a. Further, when counting down from this state of 256 to 1, all of the outputs A become "0", and at this time, a borrow output is added from the counter 34b to the counter 34a. Then, when the tone arm 1 further moves from the state where all the outputs A are "1" and a pulse signal P is added and a count-up is performed, the output of the counter 34a is caused by the carry output according to the distance traveled.
Qa ₁ , Qa ₂ , the 9th bit of the 10-bit counter,
One or both of the 10th bits becomes "1", and at this time, the output B of the OR gate 46 becomes "1", and it is detected that 256 has been overflowed. In this state, the output Qa ₃ (hereinafter referred to as output C), that is, the 11th bit output is "0". In addition, if the tone arm 1 further moves in the opposite direction from the state in which the outputs A are all "0" and counts down the signal P, either or both of Qa ₁ and Qa ₂ will change due to the borrow output. "1"
As a result, the output B becomes "1", and the 11th bit output C becomes "1" because the counter 134a underflows, and it is detected that an overflow below 0 has occurred. As described above, the output A represents an arbitrary bit output within 8 bits from the counters 34b and 34c. In addition, the above output B is in the range exceeding the above 8 bits.
Indicates whether the has moved or not. That is, the counter 34
If b, 34c overflow or underflow, the tone arm 1 moves only within a 10-bit range, so Qa ₄ to Qa ₁ are further subtracted from all "1", and the output CQa ₃ becomes "1". As mentioned above, when there is an underflow exceeding 256, the input of the D/A converter 35 is set to "11111111".
, and when there is an overflow below 0, the above input can be held at "00000000". Therefore, if the above input is Y, A, B,
There are eight possible cases regarding the relationship between C and Y, as shown in the table below.

[Table] In the case of (1) to (4) above, B = "0", so there is no overflow or underflow, that is,
Since this is the region β in FIG. 5, the output A becomes the input Y as it is. In the case of (5), B = "1" and C = "0", so there is an overflow, that is, the area of γ in Fig. 5, and Y
is held at "1". In the case of (6), since B = "1" and C = "1", there is an underflow, that is, the area of α in Fig. 5, and Y
is held at "0". In the case of (7), since B=“1” and C=“0”, there is an overflow (region of α), and Y is held at “1”. In the case of (8), since B=“1” and C=“1”, there is an underflow (region of α), and Y is held at “0”. The above table can be further simplified as follows.

[Table] In the above table, × indicates that it may be “1” or “0”. If a logical formula for Y is obtained from this table, Y=A.+B. When this logical formula is realized, the circuit configuration shown in FIG. 4 will be obtained. still,
This circuit does not hold the lower 4 bits of the 10-bit counter, but this is because most of the D/A conversion output is determined by the upper bits, so to simplify the circuit configuration, the lower 4 bits of the 10-bit counter are not held. Only bits are held. The above description has been made regarding the case where the present invention is applied to a record player as shown in FIG. It can be applied to control devices. The present invention comprises a driving means 1 for a controlled object, a position detecting means 8 for generating a number of pulses corresponding to a moving distance of the controlled object from a target stop position and a discrimination signal indicating the moving direction thereof, and the above-mentioned Start counting the pulses in response to a stop command signal applied to the driving means, and count up or count down the pulses in response to the discrimination signal to output a count value having a first number of bits (10 bits). a counter 34; and a D/A converter 35 which has a second number of bits (8 bits) smaller than the first number of bits and is supplied with a count value of the second number of lower bits in the count value. and when the controlled object moves from the target stop position, the driving means is controlled by the output signal of the D/A converter to move the controlled object to the target stop position, and , when the movement distance of the controlled object from the target stop position exceeds a range that can be expressed by the count value of the second number of bits supplied to the D/A converter, the D/A converter The present invention relates to a position control device that maintains an output signal at a predetermined magnitude. Therefore, according to the present invention, in this type of position control device, when the controlled object moves far from a predetermined position, the controlled object can be returned quickly, and the D/A converter can also be used as a bit. A small number can be used.

[Brief explanation of the drawing]

FIG. 1 is a perspective view and circuit diagram of main parts of a record player to which the present invention can be applied, FIG. 2 is a plan view of the slit plate of FIG. 1, and FIG. 3 is a waveform diagram of each part of FIG. Figure 4 is a circuit diagram showing an embodiment of the present invention, and Figure 5 is a D/A diagram for tone arm movement.
It is a figure which shows a conversion output. In addition, in the symbols used in the drawings, 1...Tone arm, 6...Horizontal drive motor,
8...Horizontal position detector, 34...Counter, 35
...D/A converter, 36...Horizontal control circuit, 40
...This is a horizontal drive circuit.

Claims (1)

[Scope of Claims] 1. A drive means for a controlled object; a position detection means for generating a number of pulses corresponding to a moving distance of the controlled object from a target stop position and a discrimination signal indicating the direction of movement; a counter that starts counting the pulses in response to a stop command signal applied to the drive means, and counts up or down the pulses in response to the discrimination signal to output a count value having a first number of bits; a D/A converter having a second number of bits smaller than the first number of bits and supplied with a count value of the second number of lower bits in the count value; When moving from the target position, the drive means is controlled by the output signal of the D/A converter to move the controlled object to the target stop position, and the stop target of the controlled object When the moving distance from the position exceeds a range that can be expressed by the count value of the second number of bits supplied to the D/A converter, the output signal of the D/A converter is maintained at a predetermined magnitude. A position control device designed to