JPS6127802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tone arm control device for a record player, and in particular, when performing an auto lead-in operation, the tone arm is accurately rotated to a desired position by electronic control. It is something.

In conventional record players, operations such as automatic lead-in and automatic lead-out of the tone arm are performed exclusively by mechanical driving means. Auto lead-in can be performed, for example, by transmitting the rotation of the motor to the arm shaft via a gear mechanism, and when the arm rotates to the target position, pulling a plunger to separate one of the gears. There is something that makes it stop. With such a mechanical configuration, it is difficult to accurately stop the arm at a target position, and noise may be generated during operation, which is undesirable.

The present invention provides a tone arm control device that eliminates the above drawbacks. That is, the present invention provides the tone arm with electromagnetic driving means, and
When performing auto lead-in, the drive means is controlled to smoothly rotate the tone arm and accurately stop it at a desired position.

Embodiments of the present invention will be described below 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 means of an arc shaft 2, and vertically rotatably in the directions of arrows c and d by a shaft 3, as is conventionally known. A cartridge 5 having a regeneration needle 4 at its tip and a track interval detector 37 are 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 at its center.
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.
It is provided to rotate the body 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. Thereby, the tone arm 1 can 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 pitch of the slits in the first slit portion 31a and the pitch of the second slits 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 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, the above two sine wave signals are a of tone arm 1.
One sine wave signal leads the other sine wave signal in phase by π/4 depending on the direction of rotation or the direction of rotation in the b direction. In the detection circuit 32,
Each of the above-mentioned sine wave signals is converted into a pulse signal, and the number of pulse signals corresponding to the rotation angle of the tone arm 1 is outputted as a horizontal position detection pulse signal P, and the rotation direction is detected by detecting the above-mentioned phase difference. A direction discrimination signal S 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 P and direction determination signal S obtained from the detection circuit 32 are applied to a counter 34. The counter 34 counts up the pulse signal P based on the discrimination signal when the arm 1 is rotated in the direction of the arrow a, and counts up the pulse signal P based on the discrimination signal when the arm 1 is rotated in the direction of the arrow b. The pulse signal P is then counted down. On the other hand, when the inter-track detector 37 detects that the arm 1 has been rotated to a predetermined position, the system control circuit 38 sends an instruction signal to the counter 34 and the horizontal drive circuit 40 to stop the rotation and start the counter. is added, thereby causing the counter 34 to start counting. The count output of the counter 34 is converted into an analog voltage by a D/A converter 35 and applied to a 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 an interval immediately before a pre-programmed song 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 instruction signal and starts counting the pulse signal P as shown in FIG. 3A applied from the detection circuit 32. 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, the counter 34 is
First, the pulse signal P is counted up based on this discrimination signal S. The count output at this time is D/
The A converter 35 converts the voltage into a rising analog voltage E as shown in FIG. The horizontal control circuit 36 applies a voltage V to the coil 10 based on this voltage E. This voltage V causes the tone arm 1 to move from the predetermined position to the counter 34.
After it has passed the point where, for example, five pulse signals P have been counted, it 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. Since the discrimination signal remains at "0" (low level) while this rotation is being performed, the counter 34 counts down the pulse signal P from the above count value. As a result, a falling voltage E is obtained from the D/A converter 35, and the horizontal control circuit 32 applies a voltage V to the coil 10 to rotate the tone arm 1 based on this voltage. 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 begins to rotate in the direction a again, at which time the discrimination signal becomes "1" again. . Due to this rotation, the tone arm 1 also passes through a predetermined position, and the same operation as described above is performed, and the tone arm 1 is returned from the passed position in the direction b.

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.

By presetting the count start value, the counter 34 can compensate for, for example, a shift in the timing at which the instruction signal is output. In other words, when the instruction signal of the tone arm 1 is detected at the beginning of the inter-musical section, for example, if you want to lower the tone arm 1 to the middle of the inter-musical section, the above detection position and the desired lowering position are There will be a gap between them. In such a case, a preset counter that can be preset is used in the counter 34, and by presetting this counter to a predetermined value corresponding to the amount of deviation, the desired lowering position and detection stop position of the tone arm 1 can be determined. can be matched. Further, since this counter 34 performs a counting operation only when a rotation stop command signal is applied, a counter having a small capacity can be used.

The present invention provides a song interval detection means 37 for detecting a song interval.
and electromagnetic means 6 for horizontally rotating the tone arm 1.
and rotation detecting means 8, 32 for outputting a pulse signal generated at a predetermined period as the tone arm rotates and a discrimination signal for the rotation direction, The tone arm includes a counter 34 that counts up or counts down, a D/A converter 35 that converts the counted value of the counter into an analog signal, and a control circuit 36 that controls the electromagnetic means in accordance with the analog signal. detecting a predetermined stop position of the tone arm by the song interval detection means, stopping the electromagnetic means based on the detection signal and operating the counter to count the amount of rotation due to inertia of the tone arm;
The tone arm is characterized in that the tone arm is stopped at the predetermined position by controlling the electromagnetic means via the D/A converter and the control circuit based on the output of the counter. This is related to the control device of.

Therefore, according to the present invention, the tone arm can be smoothly rotated without contact without using a mechanical interlocking mechanism, and can be accurately stopped at a predetermined position.

[Brief explanation of the drawing]

Fig. 1 is a perspective view and circuit system diagram of the main parts of a player showing an embodiment of the present invention, Fig. 2 is a plan view of a fixed slit plate, and Fig. 3 is an output waveform diagram of each part of Fig. 1. . In addition, in the symbols used in the drawings, 1...
...Tone arm, 6...Horizontal drive motor, 8...
Horizontal position detector, 10... Coil, 11... Yoke, 32... Detection circuit, 34... Counter, 35
. . . D/A converter, 36 . . . horizontal control circuit.

Claims (1)

[Claims] 1 A music interval detection means for detecting a music interval, an electromagnetic means for horizontally rotating the tone arm, a pulse signal generated at a predetermined period as the tone arm rotates, and a signal for determining the rotation direction. a rotation detecting means for outputting, a counter that counts up or counts down the pulse signal according to the discrimination signal, a D/A converter that converts the counted value of the counter into an analog signal, and a D/A converter that converts the counted value of the counter into an analog signal; a control circuit for controlling the electromagnetic means, wherein a predetermined stop position of the tone arm is detected by the song interval detection means, the detection signal is used to stop the electromagnetic means and operate the counter, and the tone arm The tone arm is stopped at the predetermined position by counting the amount of rotation due to inertia of the tone arm and controlling the electromagnetic means via the D/A converter and the control circuit based on the output of the counter. A tone arm control device characterized by: