KR920009198B1 - Linear velocity servo control circuit in recording a compact disk - Google Patents

Abstract

The circuit is for controlling the servo speed constantly in data writing mode. The circuit comprises a servo circuit (100) generating the tracking error signal of the pickup lens, a tracking coil (L1) driving the pickup to left or right side, a first low bandpass filter (200) filtering the tracking error signal, a comparator (300) converting the filtered signal to the pulse, a microprocessor (400) generating the motor driving pulse after comparing the reference frequency period, a second low bandpass filter (500) filtering the motor driving pulse, and a motor driver (600) driving the motor with the output of the second filter.

Description

Linear Velocity Servo Control Circuit for Recording Compact Discs

1 is a linear speed control circuit of a CDP for reproduction only.

2 is a linear velocity control circuit using a brush varnish motor.

3 is a circuit diagram according to the present invention.

4 is an operational waveform diagram of each part of FIG.

5 is a flowchart illustrating a generation of a linear speed control signal of the microcomputer 400 in FIG.

* Explanation of symbols for the main parts of the drawings

100: servo unit 200: first low pass filter

300: comparator 400: micom

500: second low pass filter 600: motor drive unit

700: motor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear speed control apparatus of a recordable compact disk player (hereinafter referred to as CDP), and more particularly, to a linear speed control circuit for controlling to maintain a constant linear speed when data is recorded on an optical disk.

In general, CDPs for playback are controlled to maintain a constant linear velocity of the disc. Therefore, the rotational speed of the disk describes the linear speed servo control circuit at the time of reproduction of FIG. 1 for adjusting the linear speed by slowing down the rotational speed as the pickup moves in the circumferential direction of the disk.

The EFM (Eight to Fouteen Modulation) signal read from the disk is inputted to detect and output the synchronization signal through the synchronization detection unit 1.

In addition, the clock generator 2 generates and outputs a reference frequency.

An output signal of the synchronous detection unit 1 and an output signal of the clock generator 2 are input to compare the two input signals, and detect and output the phase difference. The low pass filter 4, which inputs the phase detected signal of the phase detector 3, is filtered and applied to the motor drive circuit 5 to adjust the rotational speed of the spindle motor 6.

However, if the pickup is located on the innermost track of the disc and the linear velocity of the disc is kept constant, and the pickup is moving slowly outward with the sync fasteners playing back at 7.35KHZ, the sync pantone cycles faster. The frequency is greater than 7.35KHZ.

At this time, the phase detector (3) comparing the phase of the frequency greater than 7.35KHZ and the reference frequency generated by the clock generator (2) detects the compared phase difference and the motor dry sub-circuit (5) through the low pass filter (4) ) Is applied to slow the rotational speed of the spindle motor (5). At this time, as the pickup exits to the outer periphery, the T rotation speed of the disc becomes slower and constant linear speed adjustment is possible to read the data accurately.

As described above, since the linear speed control circuit at the time of reproduction is used only for reproduction only, in the recordable compact disc, since no data is recorded on the first blank disc, it cannot be used at the time of recording the compact disc. A linear speed control circuit was used. 2 will be described below with reference to the accompanying drawings.

After driving the motor 40 by placing the pickup at the innermost circumference of the compact disc, the microcomputer 10 detects a pulse output from a sensor of the motor 40 and checks the motor speed. If the speed of the motor 40 checked by the microcomputer 10 does not reach the normal speed (ie, about 600 RPM at the innermost circumference), the motor 40 is speeded up until the normal speed is reached.

At this time, the speed-up signal is generated by the microcomputer 10 and output to the low pass filter 20. The low pass filter 20, which inputs the speed up signal of the microcomputer 10, performs low pass filtering on the motor driving pulses and converts them to analog voltage levels. The motor drive 30 for inputting the signal converted into the analog voltage level in the low pass filter 20 outputs a drive signal to convert the speed of the motor 40 to control the linear speed.

As described above, the linear speed control circuit using the brushless motor of FIG. 2 has to use a spindle motor with a sensor, thereby complicating the servo control loop and increasing the design cost.

Accordingly, an object of the present invention is to provide a circuit capable of controlling the linear speed of the spindle motor using the tracking error signal of the servo circuit even without the speed check sensor of the motor.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is a circuit diagram of the present invention, in which the pickup is driven left and right by a tracking error signal output from the servo unit 100 which generates a tracking error signal generated in the process of tracking a track of a compact disc. A first low pass filter 200 for inputting a tracking error signal L1, a tracking error signal picked up by the cracking coil L1, low pass filtering, and a first low pass tilter 200; A pedestrian 300 for inputting the filtered signal and converting it into a spherical pulse, and a motor driving to control the linear velocity by inputting the signal converted into the spherical pulse in the comparator 300 and comparing with a set reference period. Inputs the output signal of the microcomputer 400 for generating a pulse, the second low pass filter 500 for inputting the motor driving pulse of the microcomputer 400 and low-pass filtering output, and the second low pass filter 500 Motor It consists of a motor 700 which is driven by a control signal from the drive unit 600 and the drive unit 600 for outputting a drive signal for the same.

4 is an operation waveform diagram of each part of FIG. 3, and FIG. 5 is a linear velocity control flow diagram of the microcomputer 400 in FIG. 3, and an embodiment of the present invention will be described with reference to FIGS. .

The recordable compact disc has a land (land) where the data is recorded and a groove (where the data is not recorded). Since the reflectance is different from each other, when the pickup tracks the track automatically, the servo unit 100 As a result, a tracking error signal as shown in FIG. 4A is generated. The tracking error signal generated by the servo unit 100 is input to the first low pass filter 200 while driving the pickup left and right by the tracking coil L1. As a result, the first low pass filter 200 performs low pass filtering to output a signal as shown in FIG.

The comparator 300 for inputting the signal output from the first low pass filter 200 is converted into a spherical pulse and outputs a signal as shown in FIG.

The microcomputer 400 inputting the signal converted into the square pulse by the comparator 300 generates and outputs a pulse as shown in FIG. That is, the motor speed control signal is generated by comparing the rotation speed information of the motor detected by the tracking error signal with the speed value at which the motor 700 rotates at the time elapsed from the recording start time. The second low pass filter 500 for inputting the pulse output from the microcomputer 400 performs low pass filtering to output a signal converted to an analog level as shown in FIG. The motor drive unit 600 for inputting the signal output from the second low pass filter 500 drives the spindle motor 700 to control the speed by reducing the speed of the motor and the reference frequency in the microcomputer 400. A method of generating a motor drive control signal based on the phase difference in comparison with FIG.

When the signal output from the comparator 300 is input, the microcomputer 400 enables the input signal flag to be set at the falling edge in step 5a and performs step 5b. In step (5b), after clearing the counter inside the microcomputer 400 for the counter, set a time limit for the start error search and performs step (5c).

In step (5c), the input signal flag is reset and step (5d) is performed. In step (5d), if it is detected by checking whether a polling edge of the input signal is detected, step (5g) is performed. If not, step (5e) is performed. In step (5e), step (5f) is performed after 100 ?? s has elapsed. In step (5f), the counter is incremented to perform step (5d) again. In step (5g), if the counter value is greater than or equal to the lower limit value of the set reference motor pulse period, if it is not greater than or equal to the lower limit value, step (5j) is performed and if it is greater than or equal to the lower limit value, step (5h) is performed. In step (5h), it is checked whether the reference motor pulse period in which the counter value is set is greater than or equal to the upper limit value. If the value is not equal to or greater than the upper limit value, the step (5j) is performed. Linear speed control is performed. In step (5j), the motor counter is designated and stored in a register, and then step (5k) is performed. In the step (5k) it checks whether the time limit for the start error search has passed, and if the time limit has not elapsed (step 5c), if the time limit has elapsed, and set the start error in step (51).

As described above, by controlling the linear speed using the tracking signal in the recordable compact disc, the servo loop can be simplified and the cost can be reduced.

Claims (1)

A linear speed servo control circuit of a recordable compact disc player, comprising: a servo unit (100) for generating an error signal generated by a pickup lens tracking a track of a compact disc, and output from the servo unit (100). A tracking coil L1 for driving the pickup to the left and right of the tracking error signal, a first low pass filter 200 for inputting and outputting a tracking error signal picked up by the cracking coil L1 and low-pass filtering; The comparator 300 converts and outputs the signal filtered by the low pass filter 200 into a square pulse, and inputs a signal converted into a square pulse from the comparator 300 to control the linear velocity by comparing with a reference frequency period. A microcomputer 400 for generating a motor driving pulse, a second low pass filter 500 for inputting a low frequency filtering output of the motor driving pulse of the microcomputer 400, and the second low pass. By entering the output signal of the emitter (500) circuit which is characterized by consisting of a motor drive unit 600 for driving the motor 700.

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