KR920008989B1 - Linear velosity control circuit and method of compact disc - Google Patents

Abstract

The constant linear velocity controller keeps the constant linear velocity of a compact disk by generating the same synchronous signal as in reproduction mode so that data is recorded on a blank disk. The circuit comprises a microcomputer (10) for generating synchronous signal for constand linear velocity control, a clock signal generator (20) for generating reference frequency, a phase detector (30) for detecting phase difference between the synchronous signal and clock signal, a low pass filter (40) for low pass filtering of the output signal of the phase detector, a motor driver (50) for controlling the speed of a spindle motor according to the output signal of the lowpass filter, and a spindle motor (60).

Description

Constant linear velocity control circuit and method for recording compact discs

1 is a configuration diagram of a compact disk.

2 is a constant linear velocity control circuit during regeneration.

3 is a constant linear velocity control circuit during recording.

4 is an operational waveform diagram of each part with respect to FIG.

5 is a flow chart according to the present invention.

* Explanation of symbols for the main parts of the drawings

10: microcomputer 20: clock generator

3: phase detector 40: low pass filter

50: motor drive circuit 60: spindle motor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recordable compact disc device, and more particularly, to a constant linear speed control circuit and method capable of accurately reading data during reproduction by adjusting the rotational speed of a drive motor when recording a compact disc data.

In general, data recorded on a compact disc is composed of basic units called home (PIT). As shown in the configuration diagram of the compact disc of FIG. 1, digital data is recorded in a groove PIT having a length of 3T-11T (T = 4.3218 × 10 ⁶ sec = 0.3 μm). These grooves (PIT) are formed in the same size for the same data on the inner and outer circumferences of the disk. In order to keep constant (Constont Linear VElocity), the disk rotation speed is slowed down as the pickup position moves outward.

FIG. 2 is a constant linear velocity control circuit diagram during reproduction, which inputs an EOT (Eight OT Fourteen Modulation) signal read from a disc, and detects and outputs a synchronization signal through the synchronization detector 1.

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

The phase detector 3 which inputs the output signal of the synchronous detection unit 1 and the output signal of the clock generator 2 compares the two input signals and detects and outputs the phase difference.

The low pass filter 4, which inputs the phase difference detection 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 speed of the disc is kept constant, and the sync pattern is being reproduced correctly in 7.35KHZ units, the 7.35KHZ pickup is gradually moved outward. It will be faster, resulting in a frequency greater than 7.35KHZ.

At this time, the phase detector (3) for 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 drive circuit (5) through the low pass filter (4) It is applied to slow the rotation speed of the spindle motor (6). At this time, as the pickup exits to the outer periphery, the rotational speed of the disc becomes slower and the linear speed is adjusted to read the data accurately.

The constant linear velocity control circuit at the time of reproduction is used only for reproduction. In the recordable compact disc, since no data is recorded on the first blank disc, the constant linear velocity control is performed in the same manner as in the regeneration dedicated compact disc player. There was a problem that could not be.

Accordingly, an object of the present invention is to provide a circuit and a method capable of controlling a constant linear velocity while generating the same synchronizing signal as during reproduction even in recording on a compact disc without recording.

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

3 is a constant linear velocity control circuit diagram according to the present invention, which includes a microcomputer 10 for generating a synchronization signal for constant linear velocity control, a clock generator 20 for generating a reference frequency, and the microcomputer 10. Phase detection unit 30 to detect the phase difference by comparing the signal generated by the clock generator and the reference frequency generated by the clock generator 20, and the low-pass for inputting and filtering the detected signal of the phase comparison of the phase detection unit 30 A motor drive circuit 50 for driving the filter 40 and a signal filtered by the low pass filter 40 to reduce the speed of the spindle motor 60, and an output of the motor drive circuit 50. The spindle motor 60 controls the CLV by a signal.

4 is an operation waveform diagram of each part of FIG. 3, fa) is a synchronous frequency waveform generated by the microcomputer 10, fb is a reference frequency waveform generated by the clock generator 20, and fp is a phase detector ( 30 is an output waveform diagram, and f _F ) is an output waveform diagram of the low pass filter 40.

FIG. 5 is a flowchart according to the present invention, which focuses to move the pickup to the innermost circumference of the disc so as to keep the distance between the disc and the objective lens constant so that the rotational speed of the disc up to the initial rotational speed when the pickup is on the innermost track. A first process of raising, and a second process of increasing the rotational speed of the disc in the first process to open a recording gate so that data can be recorded and generating a comparative frequency for a constant linear velocity, when the initial rotational speed is obtained; During the process, generate the frequency for the linear speed and check the drive status, and then decrease the period by △ t until the next constant linear speed comparison pulse is output, and whether the external write disable signal is received or the maximum recording end time of the disc is reached. If the write disable signal does not come out or the maximum recording end time of the disc is not reached, A third process of generating a predetermined linear velocity comparison pulse and closing the recording gate when the recording disable signal is received or when the maximum recording end time of the disc is reached is performed.

Based on the above configuration, the present invention will be described in detail with reference to FIGS. 3-5.

First, the operation of FIG. 3 will be described with reference to FIG. In order to record music data suitable for a compact disc in which no data is recorded, the same linear speed control as in playback is required during data recording. However, since there is no data containing a sync pattern in a disk on which data is not recorded, the same linear speed control in the same form as in playback is not possible, so a sync signal must be artificially generated.

In other words, if the disk rotation speed when the pickup is located at the innermost track is Xrpm, then if the pickup is gradually moved along the track from the inner track to the outer track, the track is spiraled from the inner to outer track so that the track can be followed. The pickup is automatically moved to the outer track so that the period of the synchronous clock is reduced by a predetermined period [Delta] t. Conversely, if we reduce the phase of the phase detector (PHASE DETECTOR) by Δt, the motor will gradually decrease its rotation speed, allowing constant linear speed control. In order to perform such an operation, a signal in which the period as shown in FIG. 4 is reduced by Δt is generated using the microcomputer 10 so that the frequency as shown in FIG. 4 generated by the clock generator 20 may be phased. Input to the detector 30.

Since the phase detector 30 inputs the two signals, the period of the signal such as the fourth diagram fa generated by the microcomputer 10 becomes faster, and thus, the phase detector 30 receives the same signal as the fourth diagram fp due to the phase difference. Output The low pass filter 40 inputting a signal corresponding to the phase difference output from the phase detector 30 filters and outputs a signal as shown in FIG. The motor drive circuit 50 for inputting the filtered signal output from the low pass filter 40 drives the spindle motor 60 to reduce the speed of the motor. Since the synchronization signal of the microcomputer 10 is generated, the flowchart according to the present invention of FIG. 5 will be described below.

When entering the recording mode for the first time, the pickup is moved to the innermost circumference of the disc in step (a), and then step (b) is performed. In step (b), focusing is performed to make the gap between the disc and the pickup objective lens constant, followed by step (c). Step (c) raises the disk rotational speed to about 600rpm at the initial rotational speed when the pickup is on the innermost track and then performs step (d).

In step (d), if the initial rotational speed is not checked by checking whether the initial rotational speed has been reached, perform step (c) again, and perform (e) if the initial rotational speed is reached.

In step (e), the recording gate is opened to allow data to be recorded. In step (f), a comparison pulse for a constant linear velocity is generated to output the first comparison pulse, and step (g) is performed. In the step (g), the drive state is checked, and the period until the next constant linear velocity comparison pulse is generated in step (h) is reduced by Δt to perform step (i). In step (i), the data is delayed for a predetermined time until the next comparison pulse for CLV is generated, and step (j) is performed.

In the step (j), it is checked whether the write disable signal is input from the outside or the maximum recording end time of the disc is performed. If there is no write disable signal, perform step (f) again and if there is a write disable signal, step (k) Stops recording by closing the write gate. As described above, since the data included in the sync pattern is not recorded on the non-recorded compact disc, the microcomputer generates the same sync signal as that during playback, and thus, the linear speed control can be performed.

Claims (4)

In a constant linear velocity control circuit when writing on a compact disc, a microcomputer 10 for generating a synchronization signal for constant linear velocity control, a clock generator 20 for generating a reference frequency, and the microcomputer 10 are generated. Phase detection unit 30 for detecting the phase difference by comparing the reference frequency generated by the clock generator 20 of the received signal, and low-pass filter 40 for inputting and filtering the phase comparison detected signal of the phase detection unit 30 And the motor drive circuit 50 for driving the low-pass filter 40 to reduce the speed of the spindle motor 60 by inputting the signal filtered by the low pass filter 40, and by the output signal of the motor drive circuit 50. Circuit characterized in that it consists of a spindle motor (60) for controlling the CLV. 2. A circuit according to claim 1, characterized in that the microcomputer (10) is connected with the comparison input of the phase detector (30). In a method of controlling a constant linear velocity during recording of a compact disc, the pickup is moved to the innermost circumference of the disc to focus the disc so that the distance between the disc and the objective lens is constant so that the disc is rotated up to the initial rotational speed when the pickup is on the innermost track. A first process of raising the rotational speed, and a second process of raising the rotational speed of the disc in the second process to generate a comparative frequency for a constant linear speed by opening a recording gate to allow data to be recorded when an initial rotational speed is obtained; And a third process of controlling the linear velocity by reducing the period by a predetermined time until the next constant linear velocity comparison pulse is output after generating the linear frequency comparison frequency in the second procedure. . 4. The method as claimed in claim 3, further comprising a fourth step of controlling the linear velocity in the third step and then stopping the recording by closing the write gate according to whether a write disable signal is input.

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