JPS5917028Y2 - 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.

A linear tracking arm is an arm that moves linearly to move 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 stop position of the arm is controlled by using a photocoupler to detect a slit at the arm stop position, or by digitally converting a certain position into a binary signal of several bits. was.

However, with the former type that uses a photocoupler, it is impossible to avoid slight deviations in the stopping position each time due to variations in sensitivity, etc., and with the latter type, it is difficult to avoid small deviations in the stopping position. In order to achieve this, it is necessary to increase the number of bits, but this is difficult in terms of mechanical accuracy and has the disadvantage of being expensive.

The present invention was developed in consideration of this point, and although it is based on the use of a photocoupler, it 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. The objective is to control the stopping of the arm by using the same method, thereby achieving accurate stopping of the arm.

Hereinafter, embodiments of the present invention will be described with reference to the figures.
In the figure, 1 is a light shielding plate made of acrylic or the like, on which two tracks la and lb are formed, each of which has a
Light-shielding parts 1a1, 1b+ are formed in black so as to alternate at the points, and the rest are light-transmitting parts 1a2, 1b.
2.

2 is a photocoupler, with a light emitting element 2a on one side and 2 on the other side.
The light receiving elements 2b and 2C are attached, and the light emitting element 2a
provides light in common to the two racks la and lb of the light shielding plate 1, and the light receiving elements 2b and 2C are located directly below each of the tracks la and lb.

Therefore, the light receiving elements 2b, 2C are on the track 1a,
Only light passing through each of 1 b is received.

Figure 2 is a block diagram for controlling the arm stop position.
The light-receiving elements 2b and 2C are 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 by a differential amplifier 3 as positive, negative, or zero. The linear arm drive circuit 5 is reached.

This linear arm drive circuit 5 performs forward driving with positive input and backward driving with negative human power.

In the above description, it is assumed that the photocoupler 2 moves in conjunction with the arm and the light shielding plate 1 is fixed.

At this time, the photocoupler 2
If it is located in the light shielding part 1b1, 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. In other words, the interlocking photocoupler 2
move 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 amount of light received is greater than that, the differential amplifier 3 begins to output a negative output, and the linear arm drive circuit 5 begins to drive the arm backward.

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

FIG. 3 shows another embodiment of the light-shielding plate 6, in which a light-transmitting part 6a and a light-shielding part 6b are formed so as to symmetrically divide a rectangular shape into two halves in a wedge shape.

In this case, the width of the light-transmitting part 6a and the light-blocking part 6b is the same.
' position is the stopping position.

However, it is necessary to connect an inverter to the output of one of the light receiving elements 2b and 2C.

In this case, as the photocoupler approaches the position A', the potential difference across the bridge gradually decreases, so that the arm stopping operation is performed smoothly.

FIG. 4 also shows another embodiment, in which a light shielding plate 7 is formed by connecting two light shielding plates 6 of FIG. 3 in parallel in opposite directions.

The light receiving element 2b detects the upper track, and the light receiving element 2C detects the lower tracks.

7a is a light-transmitting portion, and 7b is a light-shielding portion. In this case as well, the potential difference across the bridge gradually decreases as the photocoupler approaches the position A'', so that the arm stopping operation is performed smoothly.

However, an inverter is not required.

Note that although the above is an example in which the arm is stopped by detecting one stop position, it is also possible to selectively detect a plurality of stop positions and stop the arm.

In this case, multiple light-shielding plates are installed in parallel, and their stop position detection parts (the part that makes the amount of light received by the two light-receiving elements the same) are staggered, and multiple photocouplers are installed to control their operation. It is best to do this selectively.

Further, in the above embodiments, the photocoupler is linked to the arm, but a light shielding plate may be linked to the arm.

Furthermore, the light shielding portions 1a1 and 1b of the light shielding plate 1 shown in FIG.
If the degree of light shielding is gradually increased as the two get closer, the potential difference across the bridge will gradually decrease as the photocoupler moves toward the A position, and the arm stopping operation will be performed smoothly. .

As described above, according to the present invention, the amount of light received by the two light receiving elements is changed relative to the arm stop position by the relative movement between the photocoupler having two light receiving elements and the photocoupler. A light-shielding plate in which a light-transmitting part and a light-shielding part are formed along the direction of relative movement, and a circuit that detects the difference in the amount of light received by the light-receiving element, determines the moving direction of the arm, and stops the arm when the difference signal becomes zero. It consists of either a photocoupler or a light-shielding plate linked to the arm.

Therefore, the stop position of the arm will not shift, and the arm will always be
In addition to being able to stop the arm at a fixed position, it is also possible to determine the moving direction of the arm at a position away from the arm stop position based only 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
This figure and FIG. 4 are plan views of another embodiment of the light shielding plate. 1, 6. 7... Light shielding plate, 2... Photo coupler.

Claims (5)

[Scope of utility model registration request] (1) In a linear tracking arm that moves linearly and moves a pickup cartridge attached to the tip of the arm in the radial direction of the record, two light receiving units are arranged in a direction perpendicular to the direction of movement of the arm. In order to relatively change the amount of light received by the two light-receiving elements with the arm stop position as a border by relative movement between a photocoupler having an element and the photo coupler, a light-transmitting part and a light-shielding part are arranged along the direction of relative movement. It consists of a light-shielding plate formed with a part, and a circuit that detects the difference in the amount of light received by the light-receiving element and determines the moving direction of the arm, and stops the arm when the difference signal becomes zero. A stop position control device for a linear tracking arm in which one side is linked to the arm. (2) The stop position control device for a linear tracking arm according to claim 1, wherein the light-shielding plate has two tracks corresponding to the light-receiving elements, and light-shielding portions are formed on both tracks alternately. (3) The light-shielding plate has a wedge-shaped light-transmitting portion and a light-shielding portion formed oppositely to each other in the direction of relative movement thereof, and an inverter is connected to one output of the light-receiving element. Stop position control device for linear tracking arm. (4) The light-shielding plate has two tracks corresponding to the light-receiving elements, one track has a light-transmitting part and a light-shielding part formed in a wedge-like manner opposite to each other in the direction of relative movement, and the other track has two tracks corresponding to the light-receiving elements. 2. The stop position control device for a linear I/racking arm according to claim 1, wherein a wedge-shaped light-transmitting portion and a light-shielding portion are formed opposite to the light-transmitting portion and light-shielding portion of said one track. (5) The stop position control device for a linear tracking arm according to claim 2, wherein the degree of light shielding changes as the light shielding portions of the light shielding plate and the rack approach each other.