JPS6343638Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a pick-up access mechanism for reproducing concentric recording tracks.

There are two ways to form a recording track on a disc-shaped recording medium: one is to form it in a spiral shape, and the other is to form it in a concentric shape.The former is suitable for recording continuous signals, but it is suitable for recording discontinuous signals. The latter is more convenient for playing back still images. In the latter case,
To reproduce a recorded track, it is necessary to displace the pickup appropriately. Conventionally, a pulse motor was used as the drive source to move the pick-up in a controlled manner. However, a pulse motor has a characteristic of low torque. Therefore, this was inconvenient when accessing the pickup with great force. Therefore, it is conceivable to use a DC motor, but it is difficult to specify the amount of rotation with a DC motor, and it is difficult to shift the pickup by a fixed amount if the DC motor is used as it is.

Therefore, in view of the above-mentioned points, the present invention proposes a pick-up access mechanism that uses a DC motor to displace the pick-up in a controlled manner at a fixed pitch.

Hereinafter, the present invention will be described according to an illustrative embodiment. In this embodiment, a magnetic sheet is rotated at a field period to magnetically record and reproduce one field's worth of still images concentrically. FIG. 1 shows a plan view of the head driving section of this embodiment, and FIG. 2 shows a partially cutaway front view of the apparatus of this embodiment. As is clear from the drawings, the magnetic sheet 1 of this embodiment is attached to the chuck 4 of the rotary shaft 3 while being housed in the cartridge case 2 and is rotated at 3600 rpm, and the magnetic sheet 1 of this embodiment is rotated at 3600 rpm through the cutout window on the bottom surface of the cartridge case 2. It is in sliding contact with the magnetic head 5 that enters from 2a.
The magnetic head 5 is attached to a head support block 6, and with this head support, the lock 6 is supported by the free ends of two leaf springs 7, 7. Furthermore, a sliding block 8 supporting the fixed ends of the leaf springs 7, 7 is provided.
is slidably guided along a guide rail (not shown), making the magnetic head 5 freely displaceable in the radial direction of the magnetic sheet 1. An engagement pin 9 is installed below the sliding block 8, and the tip thereof is connected to a large diameter gear 10.
The spiral groove 10a is engaged with the spiral groove 10a. Therefore, the magnetic head 5 is shifted by the rotation of the large diameter gear 10. Large diameter gear 10
A small diameter gear 11 is meshed with the small diameter gear 11, and a helical gear 12 rotates together with this small diameter gear 11. In this helical gear 12, the upper and lower ends of the teeth are inclined by an amount corresponding to one pitch of the top gear.
On the other hand, a rotary plate 13 disposed orthogonally to the helical gear 12 has a protrusion 13a formed on its outer periphery so that the protrusion 13a engages with the teeth of the helical gear 12. It is configured. This rotating plate 13
is fixed to the shaft of the DC motor 14, and engages the protrusion 13a with the helical gear 12 every time the DC motor 14 rotates.
The direction of rotation of the helical gear 12 differs depending on whether a is engaged from below and exits upward, or engaged from above and exits downward, that is, depending on the direction of rotation of the DC motor 14. However, this helical gear 12 is the protrusion 1.
Brake spring 1 is rotated only while 3a is engaged, and presses against small diameter gear 11 when disengaged.
Since the magnetic head 5 is braked by the magnetic head 6 and stops at that position, the magnetic head 5 can be displaced in a moderate manner. Further, the rotational state of the helical gear 12 is determined by the rotation detecting means 1 which sandwiches the rotary plate 13 and makes the light emitting body and the light receiving body face each other.
5. This rotation detecting means 15 has through holes 13 in two positions of the rotary plate 13 in order to generate detection outputs when the projecting piece 13a is above and below the helical gear 12, respectively.
b, 13b are formed. Therefore, when the rotation detecting means 15 generates two detection outputs, the DC motor 14 displaces the magnetic head 5 by one trunk pitch, and the shift amount is controlled by the number of detection outputs. be able to.

As described above, according to the present invention, the pick-up (magnetic head) can be selectively displaced by the DC motor, and the effect is great. In this embodiment, the present invention is applied to a recording/reproducing device using a magnetic sheet, so the pickup is used as a magnetic head. In this case, the optical system is a pickup, and the recording/reproduction principle used by the pickup is not a problem in the present invention.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a drive unit according to an embodiment of the present invention;
FIG. 2 shows a partially cutaway front view of the same. Explanation of main figure numbers, 12...Hasuba gear, 13
...Rotating plate, 13a... Projection piece, 14... DC motor, 5... Pickup (magnetic head), 1...
Rotating recording medium (magnetic sheet).

Claims (1)

[Claims for Utility Model Registration] A recording/reproducing device that displaces a pick-up in a radial direction of a rotating recording medium using a gear drive, comprising: a helical gear that displaces the pick-up by rotation; A pick-up access mechanism comprising a rotary plate whose rotational surface is orthogonal to the rotational surface of the gear and a protrusion formed on the outer periphery engages with the helical gear, and a DC motor that rotates the rotary plate in both directions.