JPH0338671B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a disk motor servo circuit in a recording/reproducing type disk player or the like.

[Background of the invention]

A conventional example of a disk motor servo circuit that detects a mark signal for recording position alignment on a disk-shaped recording medium (hereinafter abbreviated as disk) and performs phase control in a recording/reproducing disk player is shown below using FIG. Explain in detail.

In Fig. 1, 1 is a disk, and 2 is a mark signal (hereinafter referred to simply as a mark signal) for recording positioning recorded in advance in the shape of an uneven shape on the inner circumference of the disk 1, and is The signal is aligned with the recording start point so that the mark signal position is approximately 7H (H: one horizontal scanning period) before the vertical synchronization signal of the odd field (or even field). As is well known, this is to align the address signal (not shown) on the disk 1 with the overscan portion on the playback screen and prevent the address signal from appearing on the playback screen. 3
is a photosensor consisting of an infrared light emitting diode, etc.
4 is a waveform shaping circuit that shapes the mark signal; 5
is a phase control circuit, which includes a reference signal generation circuit 6, a first delay circuit 7, a first trapezoid waveform creation circuit 8, a first sample and hold circuit 9, and a first sample and hold circuit that amplifies and processes the output of the first sample and hold circuit. 1
It is composed of a phase compensation circuit 10 and a first sampling pulse generation circuit 11. Note that since the first phase compensation circuit 10 is constituted by an inverting amplifier, symbols as shown in FIG. 5 are used for convenience. The same applies to the second phase compensation circuit 16, which will be described later. 12
is a speed control circuit, which includes a second delay circuit 13, a second trapezoid waveform creation circuit 14, a second sample hold circuit 15, and the sample hold circuit 1.
A second phase compensation circuit 16 that amplifies and processes the output signal of No. 5, and a second sampling pulse generation circuit 17.
It is made up of more. Reference numeral 18 denotes an adder circuit, and 19 denotes a monitor drive circuit, each of which is composed of an inverting amplifier. 20
is a motor, and 21 is a frequency generator.

In such a system, when the disk 1 is rotated using a motor starting circuit (not shown), the photosensor 3 detects the mark signal 2, which passes through the waveform shaping circuit 4 to the first sampling pulse generating circuit 1.
Enter 1. On the other hand, the output signal of the reference signal generation circuit 6 is delayed for a predetermined time by the first delay circuit 7, and further passed through the first trapezoid waveform creation circuit 8.
The signal is input to the first sample and hold circuit 9. In the sample hold circuit 9, a phase comparison is performed between the output signal of the first sampling pulse generation circuit 11 and the output signal of the first trapezoid waveform generation circuit 8, and the error signal is passed through the first phase compensation circuit 10. , after being amplified and processed, is input to the adder circuit 18.

The speed control circuit 12 also controls the rising signal portion of the output of the frequency generator 21 directly connected to the motor 20 to a second
The second delay circuit 13 delays the signal by a predetermined time.
The trapezoid creating circuit 14 creates a trapezoid waveform, while the second
The sampling pulse generating circuit 17 generates a sampling pulse, and its rising signal portion is input to the second sample hold circuit 15 without delay to perform speed detection. The output signal of the second sample hold circuit 15 is transmitted to the second phase compensation circuit 1.
6, after being amplified and processed, the phase control circuit 5
is input to the adder circuit 18 together with the output signal of.
Furthermore, via the motor drive circuit 19, the motor 20
is under control.

Conventionally, when the power supply voltage or ambient temperature changes in such a system, the sampling signal obtained from the output of the reference signal generation circuit 6 and the output of the mark signal waveform shaping circuit 4 via the first sampling pulse generation circuit 11 is generated. The phase relationship with the pulse changed, causing the recording position to fluctuate. If this recording position deviates from the normal position, (1) an address signal may appear on the playback screen.

(2) Although detailed explanation has been omitted, in the jitter servo system, the phase error between the reference signal and the reproduced signal may exceed the detectable range, making it difficult for the jitter servo to pull in.

Such problems were occurring.

As a result of the inventor's investigation, it was found that the recording position fluctuates by a mechanism as shown in FIG.

In FIG. 2, a indicates the operation mode of the second trapezoid waveform generating circuit 14 in the speed control circuit 12;
b shows that of the first trapezoid waveform generating circuit 8 in the phase control circuit 5; for convenience, the initial offset voltage at the sampling point is omitted, and the slope of the trapezoid waveform is assumed to be the same.

First, in Figure 2 a, when the speed control system is operating at point A, for example, if the positive power supply voltage changes from V ₁ to V 2, _{the sampling point will change from point A 1 .}
B Moves to ₁ point and the sample voltage decreases by Δe. In the figure b, the sampling point by the sampling pulse moves from point A ₂ to point B ₂ so as to cancel out this variation Δe, and the sample hold voltage increases. The reason for this is that since the motor rotation speed determined by the phase control circuit 5 is constant, the DC voltage output from the adder circuit 18 in FIG. 1 always operates to be constant. On the other hand, since the sampling pulse (the output signal of the first sampling pulse generation circuit 11 in FIG. 1) is a pulse signal obtained by waveform-shaping the mark signal output from the photosensor 3 in FIG. The mark signal will move relative to the reference trapezoid waveform. This reference is a frame signal of an external video signal for recording, and since the mark signal is a signal indicating the position on the disk, the recording position will eventually move by a time ΔT corresponding to the sample voltage fluctuation Δe.

Additionally, related devices of this type include:
For example, Japanese Patent Application Laid-Open No. 58-97136 can be mentioned.

[Purpose of the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for configuring a disk motor servo for a recording/reproducing disk player, which eliminates the drawbacks of the above-mentioned known examples and causes less fluctuation in the recording position even when the power supply voltage changes, for example.

[Summary of the invention]

The main point of the present invention is that by configuring the direction of the phase control circuit output change and the speed control circuit output change direction in response to power supply voltage fluctuations and temperature characteristic changes to be opposite to each other, it is possible to It suppresses fluctuations.

That is, (1) With respect to power supply voltage fluctuations, it is necessary that the difference in the number of phase inversion stages from the trapezoid type comparator circuit to the addition stage in the speed control system and the phase control system is an odd number. This will be explained using FIG. In the figure, a shows the trapezoid waveform of the speed control system, and b and b' show the trapezoid waveform of the phase control system.

When the power supply voltage fluctuates and the detection characteristics change from the solid line to the broken line, if the difference in the number of phase inverting stages between the speed control system and the phase control system is an odd number as shown in diagram b', the lower In order to cancel the offset voltage generated on the side, the characteristics change upward in the diagram b', and the offset voltage generated can be suppressed in the addition stage.

(2) Regarding changes in temperature characteristics, it is necessary that the slopes of the trapezoid waveforms of the speed control system and the phase control system viewed from the addition stage are opposite to each other. This will be explained using FIG. In the figure, a shows the trapezoid waveform of the speed control system, and b shows the trapezoid waveform of the phase control system. When the CR time constant that makes up the trapezoid type comparison circuit increases and changes from the solid line to the broken line, if the slopes of the trapezoid waveforms seen from the adder stage are opposite to each other as shown in the figure, then in figure a In order to cancel the generated offset voltage, the characteristics change upward in Figure b, making it possible to suppress the offset voltage generated in the addition stage. Putting these together, the results are as described above.

[Embodiments of the invention]

The present invention will be explained using FIGS. 2 and 5. Further, in FIG. 5, parts having the same functions as those in FIG. 1 are designated by the same numbers, and their explanations will be omitted.

In Fig. 2a, as shown in the conventional example, when the speed control system is operating at _one point A, if the power supply voltage changes from V ₁ to V ₂ , the sampling point will be from A ₁ to B. Moves to ₁ point and the sampling voltage decreases by Δe. In FIG. 5, this variation Δe is the output voltage of the second sample-and-hold circuit 15, and is led directly to the addition circuit 18 with its polarity. However, since the motor rotation speed is constant, adding circuit 1
8 output voltage is also constant, and the first phase compensation circuit 1
Δe so that the output voltage of 0 cancels out this fluctuation Δe
Only the voltage increases. Since the first phase compensation circuit 10 is constituted by an inverting amplifier, it operates so that the output voltage of the first sample and hold circuit 9 decreases by Δe. Therefore, in Fig. 2b, the sampling point A ₂ before the power supply voltage fluctuation moves to the B ₃ point where Δe has decreased, but since the time from the origin O ₂ to the sampling point does not change, the recording position is It will not change.

In addition, in FIG. 5, only the power supply voltage fluctuation was explained, but since the same explanation can be given to the temperature characteristic change, a detailed explanation will be omitted.

Further, FIG. 6 shows a second embodiment of the present invention. The operation of the speed control circuit 12 is the same as that of the known example shown in FIG. 1, but the configuration of the phase control circuit 5 is changed. That is, a trapezoid waveform is created from the mark signal waveform shaping circuit 4 output signal in the first trapezoid waveform creation circuit 8, and on the other hand, after inputting the output of the reference signal generation circuit 6 to the first delay circuit 7, the first trapezoid waveform is created. A sampling pulse generation circuit 11 generates a sampling pulse, and a first sample hold circuit 9 detects a phase error.

〔Effect of the invention〕

According to the present invention, since the direction of the phase control circuit output and the direction of the speed control circuit output are reversed with respect to power supply voltage fluctuations and temperature characteristic changes,
For example, the recording start point of the external video signal for recording will not deviate from the predetermined position due to fluctuations in the power supply voltage. Therefore, the address signal does not appear on the live screen, and the jitter servo system performs the pull-in operation stably.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional servo circuit, Figure 2 is a block diagram of a conventional servo circuit.
Figures a and b are waveform diagrams of trapezoid voltages in the speed control system and phase control system. Figures 3 a, b, and b' are illustrations of suppressing the generated offset voltage against power supply voltage fluctuations. Figure 4 a and b are temperature characteristics. FIG. 5 is a block diagram of the first embodiment of the present invention, and FIG. 6 is a block diagram of the second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Disk, 2... Mark signal for recording position alignment, 5... Phase control circuit, 8... First trapezoid waveform creation circuit, 12... Speed control circuit,
14...Second trapezoid waveform creation circuit, 20
... Motor, 21 ... Frequency generator.

Claims (1)

[Claims] 1. A phase detection circuit and a phase control circuit that perform a phase comparison between a reference signal and a mark signal for recording positioning provided in advance on a disc-shaped recording medium, and a means for detecting the rotational speed of a disc motor. and a speed control circuit, in a disk motor servo circuit of a recording/reproducing type disk player or the like which controls a disk motor by adding the output signal of the phase control circuit and the output signal of the speed control circuit, A disk of a recording/reproducing type disk player, characterized in that the direction of the voltage change of the speed control circuit output signal and the direction of the voltage change of the phase control circuit output signal at the addition point due to fluctuation are opposite to each other. Motor servo circuit. 2. A phase detection circuit and a phase control circuit that perform a phase comparison between a reference signal and a mark signal for recording positioning provided in advance on a disc-shaped recording medium, a means for detecting the rotational speed of a disc motor, and a speed control circuit; In a disk motor servo circuit of a recording/reproducing disk player or the like, which controls a disk motor by adding the phase control circuit output signal and the speed control circuit output signal, the addition point due to fluctuations in ambient temperature. A disk motor servo circuit for a recording/reproducing disk player, characterized in that the direction of voltage change of the speed control circuit output signal and the direction of voltage change of the phase control circuit output signal are opposite to each other.