KR920008292B1 - Linear speed control method of compact disk - Google Patents

Abstract

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Description

Constant linear velocity control method for recording compact discs

1 is a control block diagram of a constant linear velocity at the time of reproduction.

2 is a constant linear velocity control block diagram at the time of recording according to the present invention.

3 is a timing diagram of a reference signal applied to the present invention.

4 is a timing diagram according to FIG.

* Explanation of symbols for main parts of the drawings

10: phase comparator 15: LPF

20: motor drive unit 25: drive motor

30: rotation detection unit

The present invention relates to a linear speed control method for a compact disc, and more particularly, to a constant linear speed control method for recording a compact disc capable of recording information on a recordable compact disc.

In general, a compact disk method refers to a digital audio disk that reproduces a very high quality sound using light from a small 12 cm diameter disk for more than an hour.

In order to reproduce information on a compact disc in this manner, a control is required to maintain a constant linear velocity, which is a CLV (Constasnt Linear Velocity) control circuit. The information here means control data in the form of voice data and bits.

In other words, the CLV control circuit rotates the compact disc quickly when the pickup position is located on the inner circumference and slowly rotates the pickup position on the outer circumference to maintain the inner and outer circumferences on the compact disc at the same linear speed. To keep pace.

FIG. 1 is a block diagram of a constant linear velocity control during reproducing. The synchronization detecting unit 5 detects and outputs a bit synchronizing clock as control data by inputting digital information of a compact disc for exclusive use of the reproduction to the input terminal 1H, and the synchronization detecting unit ( A phase comparator 10 for inputting the output of 5) and the system clock of the input terminal 2H and outputting a phase compared detection signal, an LPF 15 for low-pass filtering the output of the position comparator 10, and It consists of a motor drive unit 20 for driving the drive motor 25 in accordance with the output of the LPF (15).

Briefly describing an operation for controlling a constant linear velocity during reproduction of a compact disc based on the above configuration, the output of the synchronization detector 5 is a bit synchronization clock and the clock input to the input terminal 2H is a system clock.

If it is assumed that the pickup position of the compact disc moves from the inner circumference to the outer circumferential direction, the bit clock of the synchronous detection section 5 becomes faster. At this time, the phase comparator 10 applies the comparison output to the LPF 15. Therefore, the motor driving unit 20 inputs the output of the LPF 15 to control the rotation speed of the drive motor 25 slowly. In other words, the motor driving unit 20 is to apply a voltage level corresponding to the phase difference down to the driving motor 25. In this case, the driving motor 25 operates like the voltage controlled oscillator of the PLL.

As described above, when reproducing the compact disk, the bit clock recorded on the compact disk is compared with the internal system clock to maintain a constant linear velocity. However, it was impossible to record information on a recordable compact disc. That is, in recent years, a recordable compact disc has been developed with the development of a recording medium. However, since there is no bit clock information as control data on the recordable compact disc, constant linear velocity control cannot be performed.

It is therefore an object of the present invention to provide a constant linear velocity control method capable of recording information on a recordable compact disc.

The present invention for achieving the above object is characterized by generating by increasing the period of the reference signal with time using an internal reference clock frequency to maintain a constant linear speed.

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

2 is a block speed control block diagram during recording according to the present invention. The microcomputer 100 for generating and generating a cycle of a reference signal with time by counting an internal reference clock frequency by a predetermined number and a driving motor. A rotation comparator 30 for detecting and outputting a rotation clock of the circuit 25, a phase comparator 10 for comparing and detecting a phase according to the output of the detection unit 30 of the microcomputer 100; And an LPF 15 for inputting the output of the phase comparator 10 to filter the memory, and a motor driving part 20 for inputting the output of the LPF 15 to drive the driving motor 25. .

3 is a timing diagram of a reference signal applied to the present invention.

4 is a timing diagram according to FIG. 2, and FIG. 4a shows an output waveform of the microcomputer 100, FIG. 4b shows an output waveform of the rotation sensing unit 30, and FIG. 4c shows the phase. The output waveform of the comparator 10 is shown, and FIG. 4d shows the output waveform of the LPF 15.

With reference to the above-described configuration, the present invention will be described in detail with reference to FIGS. 2 to 4 above. In order to record information on a recordable compact disc, it is most important to maintain a constant linear velocity. That is, in FIG. 2, the linear speed may be a problem depending on how the microcomputer 100 generates a reference signal having a period increased with time.

In order to maintain a constant linear velocity in the compact disc, the drive motor 25 must have a predetermined number of revolutions suitable for the current recording position radius. As the radius increases, the rotational speed of the drive motor 25 should be slow, so that the rotation speed inversely proportional to the radius should be obtained.

If you express it as a formula,

In the above formula (1)

In Equation (2), it can be seen that the rotational speed per minute of the drive motor is inversely proportional to the recording position radius. Here, m is the number of clocks that can be obtained per revolution of the drive motor 25 to obtain a pulse lock.

Since taking the reciprocal in Equation (3), the pulse width is obtained.

Therefore, in the above equation (4), the pulse width is proportional to the radius ri.

Since the control data are rolled along a spiral-shaped track that continuously changes with time, it is difficult to change the pulse width at every instant, so that a tolerance of a constant linear velocity that may exist in the disc is allowed. The TR value may be changed within the range.

That is, T _R1 = ri × C ^-1 and T _Rj = _rj × C ^-1 (where T _rj is the period of f _R in _rj ) must be the same, meaning that the time required to scan the entire disk and the microcomputer The output time of 100 should be the same. Therefore, the total length L _t of n tracks is

The scanning time t of all n tracks is

Increasing the width of the reference signal by ΔT

If the period of f _R in the nth track is T _Rn, then T _Rn = T ₀ + (K-1) ΔT

In the above formula (6)

Substituting Formula (1)-Formula (8) from the above Formula (9),

Where T _RO = r ₀ C1 ^-1 , T _Rn = r _n C ^-1 , L _t / Vo is time t, and Vo = constant linear velocity.

Based on Equation (10), ΔT of the current compact disc is 0.2148159334 × 10 ⁻⁶ sec.

to be. In this case, Vo is assumed to be 1.3 m / sec.

Referring to FIG. 3 to help understand the obtained equation (11), when a3 in section (3a) is for example the internal reference clock that is constantly output from the clock generator inside the microcomputer 100 a2 In the section, the reference clock and ΔT should be summed and output, and in the a3 section, the reference clock and 2ΔT should be summed and output. That is, when the pickup position is located on the first track of the disc, the reference signal of the a1 section is output, and when the pickup position is located on the second track, that is, when it is rotated one time, the reference signal of the a2 section is output. In the case of continuous two revolutions, the reference signal of the a3 section is output to control the constant linear speed.

However, it is virtually impossible for the microcomputer 100 to output a reference signal such as (3a). This is because DELTA T is extremely small as in Equation 11 above. Therefore, the present invention is characterized in that the reference signal as shown in (3b) of FIG. 3 is generated, and the reference signal is output by counting a predetermined number of internal reference clocks within a certain speed control tolerance. In section (3b) b1, b2, b3, b4, b5... Counting bx increases the ΔT in the interval b11.

Subsequently, an embodiment of the present invention will be described. If the number of x is 121 in a currently used compact disc, the reference signal is 13 μsec, and if the number of x is 149, the reference signal is 16 μsec. ) Is calculated by dividing by ΔT × X. Dividing by 2 is for counting the half period of the reference signal.

Therefore, the output of the microcomputer 100 and the output of the rotation detecting unit 30 are detected by comparing the phase in the phase comparator 10. The output waveform at this time is shown in Figure 4 (4a) shows the output of the reference signal of the phase micom 100, where the number of x is 2. 4b is an output waveform of the rotation detecting unit 30, which is always a constant linear velocity, so the period is constant. When the waveforms of (4a) and (4b) are compared in phase with the phase comparator 10, the waveform is a waveform of (4C), where the T ₁ section is a phase comparison detection output. Comparing this to (3a), section b1 corresponds to section a1 / 2 and section b11 corresponds to section a2 / 2, so that (3a) outputs an increased reference signal every revolution, and (3b) rotates. To increase the reference signal for each interval of.

That is, the reference signal generation process of (3b) is represented by the following equation, ΔT / 2 × X {where ΔT is (T _Rn + T _RO ) × (T _Rn -T _RO ) / 2L _t / Vo-T _Rn -T _RO ) and X is the counting number of the reference signal}, each time X increases by an integer multiple, accumulatively adding to the period of the reference clock frequency to generate the reference signal.

Here, the reference signal is a frequency having a continuously increasing width with time, and X is a counting number existing within a tolerance range. For example, if the reference signal having the same pulse width may be output to the nth track and the n + 7th track of the compact disc, the X becomes 7. At this time, the microcomputer 100 outputs the first reference clock frequencies of the first seven internal clocks, and then outputs the reference clock frequency + DELTA T / 2 x 7 and then the reference clock frequency + DELTA T / 2 x 7 Output seven.

That is, the number of X is always constant, but the width of the reference signal varies with time. In other words, the output of the microcomputer 100 is output as shown in (3C) of FIG. Here, the example of (3C) is an example assuming that X is 5. Subsequently, when the waveform of (4C) is input to the LPF 15, the waveform of (4d) is obtained.

Therefore, the motor driver 20 applies the output of which the voltage is down by the waveform of (4d) to the drive motor 25 so that the drive motor 25 is equal to the voltage down of the motor driver 20. The rotation speed is reduced. Therefore, since a constant linear velocity is maintained and the period of the reference signal of the microcomputer 100 increases with time, the rotational speed of the disk gradually decreases toward the outer periphery. The above method is not limited to the compact disc player, but may be widely used in a field requiring a constant linear velocity by controlling the rotation of the disc.

As described above, there is an advantage that information can be recorded on a recordable compact disc by controlling a constant linear velocity.

Claims (3)

A method for controlling a constant linear velocity of a compact disc player for recording information on a recordable compact disk, comprising: a reference generated by increasing a period of a reference signal over time using an internal reference clock frequency to maintain a constant linear velocity A phase comparison process for comparing and detecting a phase with a phase comparator by inputting a signal generation process, a reference signal obtained from the reference signal generation process, and a rotation clock signal of the drive motor output by the rotation sensing unit; Filtering process for low pass filtering with LPF by inputting the output of the phase-compared detection output, and driving the low frequency filtered output from the filtering process to generate a changed output according to the driving motor control for controlling the drive motor with the motor driving part. Characterized by the process A constant linear velocity when a control method of a compact disc record. The method of claim 1, wherein the reference signal generation process is performed by the following equation, ΔT / 2 × X (where ΔT is (T _Rn + T _RO ) × (T _Rn −T _RO ) / 2L _t / Vo-T _Rn T _RO ), and X is the counting number of the reference signal. The reference signal is cumulatively added to the period of the reference clock frequency whenever X increases by an integer multiple. Constant linear velocity control method for recording compact discs. The method of controlling a constant linear velocity of a compact disc according to claim 2, wherein ΔT is 2x0.107407967x10 ^-5 .