JPH0411220Y2 - - Google Patents

Description

[Detailed description of the invention] This invention uses a DAD (Digital Audio Disk) device, etc., to send a pick-up to detect information signals non-contactly from a disk on which information signals such as audio signals are recorded. Accordingly, regarding the pulse motor drive circuit for moving the disc relative to the disk surface, the drive voltage of the pulse motor is cut off particularly at the end of the pickup feeding.

Recently, digital technology has become popular, in which information signals such as audio signals are recorded optically in a spiral manner in the form of pits on a disk and then reproduced. Audio. PCM playback devices such as discs (DAD) have been developed and are attracting attention. A pickup that detects information signals from such a disk is, for example, a tracking system that detects lateral vibration of the disk due to eccentricity of the disk. Tracking from error detection circuit. The disk surface is moved by driving a pulse motor by counting pulses (referred to as sending pulses) from a pulse generation circuit that generates pulses when an error signal exceeds a predetermined level or when a predetermined time elapses.

However, in the above-mentioned pulse motor drive method, for example, in a two-phase excitation method pulse motor, the drive output period required to send a pickup is actually T period as shown in FIG. Regardless, the output is applied.

This is because the maximum value of the output range is set to ensure that the pulse motor is driven at a predetermined angle, so even though the pickup has actually been sent, the drive voltage is not applied to the pulse motor. -ing

In other words, all the voltage other than the voltage required to drive the pickup is converted to heat, which can cause malfunctions such as the pulse motor often stopping due to heat generation, which can have a serious negative impact on the pulse motor. It was something to give.

The present invention has been developed in view of the above-mentioned drawbacks, and embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 2 shows an embodiment of the present invention. In the figure, an information signal recorded on a disk (not shown) is detected by a pickup 1, and an output signal of this pickup 1 is tracked. In the error detection circuit 2, a tracking component is detected. The tracking component is input to the comparator 3 which outputs a rectangular wave when it reaches a predetermined level or more or after a predetermined time has elapsed. The output of the comparator 3 is applied to one-shot multivibrators 4a and 4b which send out pulses for a predetermined period at the rise and fall of the output of the comparator 3. One shot. The output of the multivibrator 4a is applied to the clock pulse input terminal CP of the parallel output type binary counter 5. The binary counter 5 outputs a binary coded decimal code according to the input clock. Also, binary counter 5
The binary-to-decimal conversion circuit 6 generates a single output. The "4" output of the base-of-10 output is applied to the reset terminal R of the binary counter 5, and is connected so that the output of the base-of-10 output becomes "0" when the binary counter 5 calculates four pulses. Reference numeral 7 denotes a matrix circuit, which is a logic circuit that generates a combination of outputs according to the outputs of the binary/decimal conversion circuit 6. For example, when a "0" output is input, the outputs of M1 and M2 are selected as the matrix output, and when the "1" output is input, the outputs of M2 and M3 are selected. This corresponds to the combination of excitation coils of the pulse motor shown in FIG. 1 (shown in FIG. 3). The outputs of the matrix 7 are applied as one input to AND circuits 8a, 8b, 8c, and 8d, respectively. The other inputs of the AND circuits 8a, 8b, 8c, and 8d are flip-flops. The Q output of flop 9 is applied. Flip. Flop 9 is one shot. A set terminal S to which the output of the multivibrator 4a is input and a one shot terminal. It has a reset terminal R to which the output of the multivibrator 4b is input. The outputs of the AND circuits 8a, 8b, 8c, and 8d are the transistors 10 and 10, respectively, which are drivers.
It is applied to a, 10b, 10c, and 10d.
11a, 11b, 11c, and 11d are drive coils of a pulse motor (not shown), and +V is a pulse motor drive voltage.

Next, the operation of the present invention having such a configuration will be explained.

Tracking detected from Pickup 1.
When the error signal exceeds a predetermined level or exceeds a predetermined time, the comparator 3 outputs the output shown in FIG. 4A. Therefore, when the output of comparator 3 rises, one shot. Multi. vibrator 4
a is activated and flips. Flop 9 is set and a "High" signal is applied to AND circuits 8a, 8b, 8c, and 8d. Then, the pulses are counted at the clock terminal CP of the counter 5, and the pulses are counted by the clock terminal CP of the counter 5, and the pulses are counted by the clock terminal CP of the counter 5.
Advance the value by 1. For example, if the previous state is sending out a "0" output, a "1" output is supplied to the matrix circuit 7, the AND circuits 8b and 8c are selected and the output is applied to the transistors 10b and 10c, and the pulse motor drive coil 11b, 11c is excited. The combination is shown in Figure 3).

Therefore, two combinations are selected from the AND circuits 8a, 8b, 8c, and 8d selected by the matrix circuit 7, and the pulse motor drive coil 11
Two sets are selected from a, 11b, 11c, and 11d, and a pulse motor (not shown) is driven at a predetermined angle.

By the way, when the pickup 1 moves a predetermined amount by driving the pulse motor at a predetermined angle, the tracking. The level drops rapidly. Therefore, the output from comparator 3 falls sharply, resulting in a one shot. Multi. vibrator 4b
is activated and flips. Reset flop 9. As a result, AND circuits 8a, 8b, 8c, 8
d closes and the driver. Transistors 10a, 10
b, 10c, 10d are cut off, and the pulse motor drive coils 11a, 11b, 11c, 1
1d is not excited.

Furthermore, tracking. As the level increases, the output sent from comparator 3 causes one shot. Multi. The vibrator 4a operates, increments the binary counter 5 by 1, and flips the flip. Flop 9 is set and AND circuit 8a,
A “1” signal is applied to one input of 8b, 8c, and 8d.

Therefore, the output of the binary-to-decimal conversion circuit 6 shifts from "1" to "2" and matrix outputs M3 and M4 are selected. Then, when the AND circuits 8c and 8d are satisfied, the pulse motor drive coils 11c and 1
1d is excited, the pickup 1 is moved by a predetermined amount, and the tracking. Flip as the level drops. Flop 9 is reset.

Thereafter, in the same manner, pulse motor drive coils 11a, 11b,
11c and 11d are excited and send pick-up 1.

Therefore, according to the present invention, the voltage applied to the pulse motor is cut off at the end of the pick-up feeding, so the voltage applied to the coils that are not necessary for sending the pick-up changes thermally, causing the pulse motor to generate heat. This can alleviate the problem and has great practical effects.

[Brief explanation of drawings]

Figure 1 is a diagram used to explain the present invention, Figure 2 is a diagram showing a pulse motor drive circuit according to the present invention, Figure 3 is an output diagram of the matrix circuit according to the present invention, and Figure 4 is similar to Figure 2. It is a waveform diagram of each part in this. 1... Pickup, 3... Comparator, 4a, 4
b...One shot. Multi. vibrator,
5... Binary counter, 7... Matrix circuit, 8a, 8b, 8c, 8d... AND circuit, 1
1a, 11b, 11c, 11d...Pulse motor drive coil.

Claims (1)

[Scope of utility model registration request] Information signals are sent spirally on the disk in a concave and convex shape.
In an optical PCM playback device that performs PCM modulation recording and optically reads it with a laser beam, it includes a pulse motor that moves a pickup that scans the disk with a laser beam and detects information signals, and an output of the pickup. a detection means for detecting a tracking error signal from the signal; and a pulse for applying a driving voltage to the pulse motor and driving the pulse motor when the tracking error signal of the detection means reaches a predetermined level or more or is output for a predetermined time or more. The apparatus comprises a motor driving means, and a means for cutting off the driving voltage applied from the pulse motor driving means to the pulse motor when the tracking error signal from the detection means changes to a predetermined level due to movement of the pickup by a predetermined amount by the pulse motor. A pulse motor drive circuit characterized by: