JPS5848269A - Detector for pickup position - Google Patents

Abstract

PURPOSE:To detect assuredly the position of a pickup with a simple constitution, by detecting via a Hall device a change of the rotary position of a permanent magnet which turns with interlocking to a pickup shifting motor. CONSTITUTION:The rotary force of a pickup shifting motor is transmitted to an arm part and a base via a worm, a worm gear, a pulley for transmission of a belt, etc. Then a pickup arm moves to perform the lead-in operation. A permanent magnet 15 which is connected to the worm, etc. and magnetized with multiple poles toward its diameter is turned with interlocking to the pickup shifting motor. Thus a change of the rotary position of the magnet 15 which is proportional to the shift of the pickup is measured by counting the number of pulses delivered from a Hall device 16. As a result, the position of the pickup can be detected assuredly with a simple constitution excluding a photointerrupter, a Schmitt trigger circuit, etc.

Description

[Detailed description of the invention] A beam air tracking record player according to the present invention.

The present invention relates to a pickup position detection device for a video disc player or a digital disc player.

In a linear tracking record player, it is necessary to detect the position of the pickup for automatic lead-in and automatic return when the end is reached.

Conventionally, a position detecting device has been constructed using a slit plate and a photointeracitor, but the photointeracitor has drawbacks such as being expensive and requiring a Schmitt trigger circuit for waveform shaping.

An object of the present invention is to provide an inexpensive pickup position detection device that does not particularly require a Schmitt trigger circuit.

FIG. 1 shows an embodiment of the present invention, in which a pickup cartridge l'a is connected to a big-adjustment arm 1b, and is rotatably attached to a pace 3 by a bearing part 2. As shown in FIG. The pace 3 has a slide bearing 4 and can slide along the guide rail 5. The drive motor 6 has a sea leaf m+7b and a belt 7c.
The worm 8 is connected to a worm gear 9 so as to rotate the worm 8, and a rope 10 is hung on the worm gear 9.
An arm portion 11 protruding from the pace 3 is coupled to the yoke 10, and as the yoke 10 moves, the arm 11 moves in the axial direction together with the pace 3.

Further, the pickup arm 1blC is equipped with a light shielding plate 12 and is housed in a photointerrupter 13 that detects the rotation angle of the pickup arm 1b.

14 is a switch, and when P-3 comes to the standard position j-A
A permanent magnet 15 is coupled to 8, and a Hall IC 16
is attached close to a permanent magnet 15, and a yoke 17 made of iron plate is arranged behind it.

As shown in FIG. 2, the permanent magnet 15 is magnetized with multiple poles in the radial direction, and the output of the Hall IC 16 changes from H-L depending on the magnetic pole N-8. Further, the yoke 17 has the function of lowering magnetic resistance, increasing magnetic flux density, and concentrating the magnetic flux on the pole IC 16.

To explain the operation in Fig. 1: During lead-in, the drive motor 6 rotates and the sea leaf m+7b.

Belt 7 cr worm 8. Worm gear9. Rope 10. Arm part 11. Pace 3. The power is transmitted and the pickup 1 is moved.

As the motor 6 rotates, the arm portion 11 turns the button 1 of the switch 14. From the moment the switch 14 is turned OFF, the ball IC 16 is turned OFF! ? By counting the number of loops and stopping the destination 6 at a certain count, the pickup 1 can be stopped at the target position.

During automatic return, - During a performance, the light shielding plate i2 and the photointeracitor 13 detect that the pickup arm 1b has rotated inward and rotates the motor 6 to move the pick-up arm f1 inward. It is sufficient to count the number of pulses of the IC 16 and generate a return signal when a certain number is counted.

By using the permanent magnet 15 and the Hall ICI 6, counting can be performed without contact, resulting in high reliability. Hall again! ``・'c'l11.,,6 can have hysteresis characteristics in the forward and reverse directions by using a built-in Schmidt and Todriger circuit whose characteristics are shown in Figure 3.
Even if the driving motor 6 rotates intermittently during a performance and the permanent magnet 15 rotates slightly in the opposite direction at the moment the motor stops, this will not cause a counting error.

Although the embodiment has been explained using a linear tracking record player, it is clear that similar effects can be obtained with a video disc player or a digital disc player.

As described above, according to the present invention, there is an advantage that a photo-interlacer and a Schmitt trigger circuit for detecting the birafatu position are not required, and an inexpensive and reliable pickup position detecting device can be obtained. .

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the main parts of the pickup position detection device of the present invention, Fig. 2 is a plan view of the counting permanent magnet and Hall IC used in the device shown in Fig. 1, and Fig. 3 is a plan view of the Hall IC shown in Fig. 2. FIG. 2 is a diagram illustrating hysteresis characteristics of IC operation. 1a...Cartridge, 1b...Pickup arm, 3...Pace, 4...Slide bearing,
5... Guide rail, 6... Monitor, 7h, 7b
...day! J-17c...belt, 8...worm, 9...worm gear, 10...-rope, 11...
...Arm portion, 12...Light shielding plate, 13...Photointeracitor, 14...Switch, 15...Permanent magnet, 16...Hall IC, 17...Yoke. Fig. 1 Fig. 2 7 Fig. 3 4n → A East Territory

Claims (2)

[Claims] (1) A position detection device for a pickup, which includes a permanent magnet that rotates in conjunction with a motor for moving the pickup, and a Hall IC whose output changes depending on the rotational position of the permanent magnet. (2) The pickup position detection device according to claim (1), characterized in that a yoke is disposed at the rear of the Hall IC.