JPH0422401Y2 - - Google Patents

Description

[Detailed description of the invention] "Purpose of the invention" (Industrial application field) The present invention relates to a drive circuit for a linear tracking arm, and in particular to a drive circuit for precisely controlling the drive motor of a linear tracking arm. Regarding.

(Prior Art) In general, a tracking arm drive device in a linear tracking type record player has a tracking arm 13 supported slidably on a rail 10 and pivoted on a base 12, as illustrated in FIG. An optical sensor 16 for detecting the tracking error amount 15 of the tracking arm 13 and a transmission mechanism 17 to which the stress of the drive motor 18 is transmitted are attached to the base 12, and the optical sensor 12 is connected to the optical sensor 12. A control circuit 19 amplifies the displacement signal from the recorder 16, and the motor 18 is driven by the output thereof, so that the tracking arm 13 always follows the record surface (not shown) at a tangential position. There is.

(Problems to be solved by the invention) However, in the above-mentioned conventional linear tracking type arm drive device, firstly, the drive motor 18 has cogging, and there are positions where the motor is likely to stop during one revolution. Second, Rail 10
The frictional force existing between the base and the other sliding parts impedes the smooth operation of the tracking arm 13, and causes the tracking arm 13 to move while exhibiting a so-called measuring motion. The drawback was that it caused vibrations and was reproduced as periodic click noise.

To explain the above phenomenon in detail, in this type of arm drive device, there is a large difference between static friction and dynamic friction, and this means that at the moment when the stress from the motor exceeds the limit of static friction force and the tracking arm 13 moves. This frictional force transfers to dynamic frictional force, and the tracking arm 13 moves at an accelerated rate, which appears as a phenomenon, and when this is repeated, it gives a periodic impact to the tracking arm, which is reproduced as noise. Become.

The present invention has been developed in view of the above points, and its purpose is to drive a linear tracking arm that eliminates unpleasant clicking noises by smoothing the movement of the tracking arm. The purpose is to provide circuits.

"Structure of the invention" (Means for solving the problems) The linear tracking arm drive circuit according to the invention detects the amount of tracking error of the linear tracking arm, and detects the amount of tracking error in accordance with the detected amount. In a linear tracking arm drive circuit configured to perform closed-loop control of a tracking arm drive motor in a direction in which the amount of the tracking arm is decreased, in order to intermittent any signal related to motor control within the closed loop at a predetermined period. A signal intermittent means is provided, the signal intermittent means comprises two switching elements connected in series oppositely in a closed loop, and is configured such that a switching signal is input to a connection point between both switching elements. There is.

(Function) When a switching signal is input to the connection point of two switching elements connected in series oppositely in a closed loop, one of the signals for controlling the motor in the closed loop, for example, the electric power for driving the motor. This allows the tracking arm drive motor to operate precisely while resisting static friction, allowing the tracking arm to move smoothly and reducing low-frequency noise and clicking noise. Occurrence can be prevented. In particular, since it is configured to use an AC power source as the switching control signal by the signal intermittent means, the operation is precise, and it is easy and inexpensive to implement.

(Embodiment) An embodiment of a linear tracking arm drive circuit according to the present invention will be described based on FIGS. 1 to 4.

FIG. 1 is a block diagram showing a basic configuration example, in which a tracking arm 1 is pivotally supported on a base 2 running along a rail 3, and is moved in a thrust direction F by a motor 4 and a drive mechanism 5. However, the position can be controlled freely. 6 is the displacement that the tracking arm 1 receives in the thrust direction by tracing on the record disc, that is,
It is an optical angle sensor for detecting the amount of tracking error, and is provided on the base 2, and in the embodiment, the tracking arm is placed between a photointerrupter consisting of a light emitting element 6a and a light receiving element 6b. By inserting a perforated light shielding plate 6c fixed to the first side, the amount of tracking error can be detected. 7 is an amplifier for amplifying the output (displacement amount) from the angle sensor 6, and 8 is a drive amplifier for controlling the motor 4 based on the output signal from the amplifier 7. It consists of Reference numeral 9 denotes a signal intermittent means inserted in the closed loop _L , and in the embodiment shown in _FIG . The connection point P between both diodes D ₁ and D ₂ is connected to the power transformer T.
The AC voltage output from the terminal is connected to TO. An integrating capacitor C is interposed between the anode side of the diode D ₂ and the earth GND, and the waveform of the signal interrupted by the signal intermittent means 9 can be smoothed to a certain extent so that the motor 4 can operate smoothly. It's becoming like that.

To explain an example of the operation in the above configuration, first, a signal corresponding to the amount of tracking error of the tracking arm 1 is output from the angle sensor 6, and then passes through the amplifier 7 to the drive amplifier 8 at the next stage.
A closed loop L that operates the motor 4 in a direction in which the tracking error amount is reduced by the power amplified by
is formed, but the signal intermittent means 9 performs an intermittent operation as described later, and the signal within the closed loop L is interrupted.
The motor 4 is driven by, for example, a pulsating flow with a duty ratio of about 50%.

An AC voltage stepped down by a resistor R is applied to the point P in the signal intermittent means 9, but in the negative region of the AC voltage, both the diodes D ₁ and D ₂ are energized, and the voltage from the amplifier 7 is The output signal is input as is to the drive amplifier 8 side.

On the other hand, in the positive region of the AC voltage, both the diodes D ₁ and D ₂ are in a blocking state, and the output signal from the amplifier 7 is blocked there.

In this way, the signal intermittent means 9 has a simple configuration and can perform on/off control at a predetermined frequency, for example, 50 Hz, and can add slight vibrations to the rotation of the motor 4. Therefore, the above base 2 and rail 3
The tracking arm can be moved at a very slow speed while constantly canceling out the static friction existing between the motor 4 and the drive mechanism 5 and the like by intermittent driving of the motor 4 described above. Furthermore, when the electric power applied to the motor 4 is interrupted at a duty ratio of 50%, it becomes 1/2, so the rotational speed also decreases, allowing for even more delicate speed control.

In this way, the tracking arm 1 can be moved faithfully to the record sound groove without stopping, so there is no movement of the tracking arm 1 due to coking of the motor or static friction. This makes it possible to prevent noise from occurring.

Figures A and B show the movement trajectories of the tracking arm, A is the one according to the present invention and B is the conventional one, in which the moving speed v of the tracking arm on the time axis t is compared. be. FIGS. 4A and 4B are characteristic diagrams at 45 RPM and 50 Hz, comparing vibration components, that is, noise components, applied to the tracking arm 1. In the conventional device shown in FIG. 3B, the movement speed v fluctuates greatly, and it is clear that periodic shocks are applied to the tracking arm, but in the device according to the present invention shown in FIG. 3A, The fluctuation in the moving speed v is small, so the movement operates smoothly, and no harmful vibrations are imparted to the tracking arm 1.

In addition, in the device according to the present invention shown in Figure 4A, the noise level has been reduced to about 1/3 compared to the conventional one shown in Figure 4B, and the S/N ratio has been significantly improved. Can be seen.

"Effects of the invention" According to the linear tracking arm drive circuit according to the invention, when a switching signal is input to the connection point of two switching elements connected in series in a closed loop, the signal intermittent means performs tracking. Any signal related to motor control within the closed loop for driving the king arm can be intermittent at predetermined intervals, so that the movement of the tracking arm can be made smooth and tracing can be made good. This makes it possible to prevent the occurrence of low-frequency noise caused by the measuring movement of the tracking arm, and to greatly improve the S/N ratio. Moreover, if the above-mentioned signal intermittent means inputs an AC voltage from an AC power supply as a switching signal, it is possible to perform intermittent operation using the power frequency of the commercial power source, and there is no need to separately provide an oscillator or the like for intermittent operation. It has advantages such as being stable, easy to implement, and inexpensive.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the linear tracking arm drive circuit according to the present invention, FIG. 1 is a block diagram showing the overall configuration, FIG. 2 is a specific circuit configuration diagram, and FIG. 3 is a block diagram showing the overall configuration. The figures are comparative diagrams showing the movement locus of the tracking arm, where Fig. 3A is a locus diagram of the one according to the present invention, Fig. 3B is a locus diagram of the conventional one, and Fig. 4 is a locus diagram of the locus of the conventional one. FIG. 4A is a characteristic diagram of the device according to the present invention, and FIG. 4B is a characteristic diagram of the conventional device. FIG. 5 is a block diagram showing a conventional linear tracking arm drive device. 1...Tracking arm, 2...Base, 3
...Rail, 4...Motor, 5...Drive mechanism,
6...Optical sensor, 7...Amplifier, 8...Drive amplifier, 9...Signal intermittent means, _D1 , _D2 ...Diode as switching element, T...Power transformer.

Claims (1)

[Claim for Utility Model Registration] The system is configured to detect the amount of tracking error of the linear tracking arm, and to control the tracking arm drive motor in a closed loop in a direction that reduces the amount of tracking error according to the detected amount. In the drive circuit for the linear tracking arm, a signal intermittent means is provided for intermittent one of the signals related to the motor control within the closed loop at a predetermined period, and the signal intermittent means is provided with an opposing signal in the closed loop. 1. A drive circuit comprising two switching elements connected in series, and a switching signal being input to a connection point between both switching elements.