JPS5917029Y2 - Linear tracking arm stop position control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stop position control device for a linear tracking arm.

The Nonia tracking arm is an arm that moves linearly and moves a pickup cartridge attached to the tip of the arm in the radial direction of the record, and is extremely good with no tracking errors.

Conventionally, the arm stop position control involves installing a photocoupler at a specific position and detecting a slit at that location to stop the arm.
Alternatively, there were devices that stopped the arm by converting a digital location into a several-bit binary signal.

However, the former requires multiple photocouplers if you want to control a large number of positions, and it is impossible to avoid slight deviations in the stopping position each time due to variations in sensitivity, etc., and the latter In order to reduce the deviation of the stop position, it is necessary to increase the number of bits.
This is difficult in terms of mechanical precision, requires complicated electrical processing, and is generally expensive.

The present invention was developed in consideration of this point, and although it uses a photocoupler, it also uses two light-receiving elements to detect the difference in the amount of light received by the elements in relation to the light-shielding plate, thereby determining the stop position of the arm. The aim is to realize this accurately at any position.

Hereinafter, one embodiment of the present invention will be described with reference to the figures.
is a light-shielding plate made of a material such as acrylic, on which two tracks la and lb are formed, each with a light-shielding part 1a1 colored black so as to alternate at point A.
, 1b1 are formed, and the rest are transparent parts 1a2 and 1b2.

This light shielding plate 1 can be moved by hand in the longitudinal direction.

2 is a photocoupler that moves in conjunction with the arm, and a light emitting element 2a is attached to one side, and two light receiving elements 2b and 2C are attached to the other side, and the light emitting element 2a is attached to two tracks la and lb of the light shielding plate 1. The light-receiving elements 2b and 2C, which commonly provide light, are located directly below the tracks la and lb, respectively.

Therefore, the light receiving elements 2b and 2C receive only the light passing through the tracks la and lb, respectively.

Figure 2 is a plot diagram for controlling the stop position of the arm.
The light receiving elements 2b and 2C are respectively connected to the ground side of the bridge circuit, and the potential difference between the connection points with the resistors R1 and R2 is detected as positive, negative, or zero by the differential amplifier 3.
It reaches the linear arm drive circuit 5 via.

This linear arm drive circuit 5 performs forward drive using positive human power and backward drive using negative human power.

In the above, the photocoupler 2 is the transparent part 1a of the light shielding plate 1
2. If located at the light shielding part 1bt, one light receiving element 2b is irradiated and the other light receiving element 2C is not irradiated.

Therefore, since the internal resistance of one light-receiving element 2b is low and the internal resistance of the other light-receiving element 2C is high, a positive output is output from the differential amplifier 3, which causes the linear arm drive circuit 5 to move the arm in the traveling direction, i.e. Move the photocoupler 2 in the direction of arrow B.

Then, when the photocoupler 2 comes to the A position of the light shielding plate 1,
Since the light receiving elements 2b and 2C both receive the same amount of light, the input to the differential amplifier 3 becomes zero, and the linear arm drive circuit 5 becomes inactive.

Therefore, the arm stops at that position.

Note that if the arm moves beyond the A position due to inertia, the light receiving element 2C is more sensitive to the other light receiving element 2b.
Since the linear arm drive circuit 5 receives a larger amount of light, the differential amplifier 3 outputs a negative output, and the linear arm drive circuit 5 drives the arm backward.

Therefore, photocoupler 2, that is, the arm is finally
Stop at a position.

In this case, by manually moving the light shielding plate 1 in the longitudinal direction, it is possible to stop the movement of the arm at an arbitrary position.

FIG. 3 shows another embodiment of the movable light shielding material 6.
is suspended between rolls 7 and 8 in an endless manner, and the negative roll 7 can be rotated by hand to make the longitudinal position of the light shielding material 6 variable.

In addition, in the above, photocoupler 2 was linked to the arm, but
The light shielding plates may be interlocked so that the photocoupler 2 can be moved by hand in the longitudinal direction of the light shielding plates.

Further, the light receiving elements 2b and 2C of the photocoupler 2 may be ones whose current changes depending on the reception of light.

From the above, according to the present invention, the arm moves linearly,
In a linear tracking arm that moves a pickup attached to its tip in the radial direction of a record, a photocoupler with two light receiving elements arranged in a direction perpendicular to the direction of movement of the arm and a photocoupler that moves the pickup attached to the tip in the radial direction of the record, a light-shielding member formed with a light-transmitting part and a light-shielding part along the direction of movement of the light-shielding member to relatively change the amount of light received by the light-receiving element;
It includes a circuit that detects a difference in the amount of light received by the light receiving element to determine the moving direction of the arm and stops the arm when the difference signal becomes zero, and one of the photocoupler and the light shielding member is interlocked with the arm, and the other is interlocked with the arm. can be moved by hand in the direction of movement of the arm.

Therefore, the arm can be stopped at an accurate position, and the position can be changed arbitrarily.

Further, even at a position far from the arm stop position, the direction of movement of the arm can be determined based on the output states of both light receiving elements.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the relationship between the photocoupler and the light shielding plate, Fig. 2 is a block diagram of signal processing from the photocoupler, and Fig. 3
The figure is an explanatory diagram of another embodiment in which the light shielding member is movable. 1... Light shielding plate, 2... Photo coupler.

Claims (1)

[Scope of utility model registration request] In a linear tracking arm that moves linearly and moves a pickup attached to its tip in the radial direction of the record, a photo sensor has two light-receiving elements arranged in a direction perpendicular to the direction of movement of the arm. A coupler, a light-shielding member formed with a light-transmitting part and a light-shielding part along the moving direction of the light-receiving element so as to relatively change the light-receiving amount of the light-receiving element after the arm stop position; It includes a circuit that detects the direction of movement of the arm and stops the arm based on the difference signal of zero, and one of the photocoupler and the light shielding member is linked to the arm, and the other is moved by hand in the direction of movement of the arm. A stop position control device for a linear tracking arm, which is characterized by being freely adjustable.