JP2574128B2 - Motor rotation control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor rotation control device for controlling the rotation of a motor used to rotate a disk in an optical video disk player.

[0002]

2. Description of the Related Art Conventional devices of this type include, for example,
As described in Japanese Patent Application Laid-Open No. S59-77675, when a reproduced horizontal synchronizing signal is lost due to a flaw or the like of a disk being reproduced, the lack is detected by a missing detection circuit, and a motor drive circuit is controlled by a motor. There was something to separate from the circuit. In general, when the reproduction horizontal synchronizing signal is lost, the motor control circuit works to increase the rotational speed of the motor, and abnormally increases the rotational speed. Therefore, in this proposed example, when the reproduction horizontal synchronizing signal is lost, the motor drive circuit is disconnected from the motor control circuit, and thereafter, the rotation changes only gradually due to the inertia of the motor.

[0003]

However, in the above-mentioned prior art, if the period of loss of the reproduced horizontal synchronizing signal is long, the change in the number of revolutions of the motor becomes large (that is, the motor is greatly decelerated). If the disk being reproduced is an 8-inch disk, the inertia of the motor is small, and the motor is immediately decelerated. Therefore, when the normal reproduction horizontal synchronizing signal is input again, there is a problem that it takes time to recover.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art. Even when the reproduced horizontal synchronizing signal is lost, the length of the missing period or the magnitude of the inertia of the motor that changes depending on the disk to be reproduced. Regardless of the above, an object of the present invention is to provide a motor rotation control device that can keep the rotation speed of the motor substantially constant.

[0005]

According to the present invention, there is provided a quasi-pulse generating circuit for generating a quasi-pulse in accordance with a reproduction horizontal synchronizing signal generated depending on the rotation of a motor. An OR circuit for outputting a logical sum of the reproduced horizontal synchronizing signal generated depending on the rotation of the motor and an output from the spurious pulse generating circuit; and a reference horizontal synchronizing signal supplied separately from the output from the OR circuit. A control circuit that compares the phase and frequency of the signal and controls the rotation of the motor based on the comparison result , and the pseudo-pulse generation circuit includes:
The first pseudo pulse that occurs first when a signal is lost is
After the last occurrence of the reproduction horizontal synchronization signal, the reference horizontal synchronization
Occurs after a certain period longer by Δt than the period of the period signal
Then, the second pseudo pulse generated next is referred to as the first pseudo pulse.
After the generation of the pseudo pulse, the period of the reference horizontal synchronization signal
Occurs after a period of time shorter by the length Δt,
The pseudo pulse generated thereafter is transmitted to the reference horizontal synchronization signal.
It occurs at the same period as the period of the signal. Where Δt is
The length is shorter than the cycle of the reference horizontal synchronization signal.

[0006]

The spurious pulse generation circuit generates a spurious pulse when a reproduced horizontal synchronizing signal generated depending on the rotation of the motor is lost. That is, the pseudo-pulse generation circuit detects the generation state of the reproduced horizontal synchronization signal generated depending on the rotation of the motor, and if the reproduced horizontal synchronization signal does not arrive longer than a predetermined period, the pseudo-pulse generation circuit generates the pseudo-pulse. A first pseudo pulse is generated as a pulse. And then, the second
The third pseudo pulse is generated shorter than the predetermined period, and the third and subsequent pulses are generated at the predetermined period.

In this way, a pseudo pulse is generated when the reproduced horizontal synchronizing signal is lost, so that a signal obtained by interpolating the missing portion of the reproduced horizontal synchronizing signal with the pseudo pulse is obtained as an output from the OR circuit. Thus, it can be supplied to the phase / frequency detection circuit as a reproduced horizontal synchronizing signal having no apparent loss. Therefore, the number of rotations of the motor can be kept substantially constant even during the missing period, and the return time when returning to the normal reproduction horizontal synchronizing signal is shortened.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing a circuit configuration of an embodiment of the present invention, and FIG. 2 is a waveform diagram showing signal waveforms of main parts in the circuit of FIG.

In FIG. 1, reference numeral 1 denotes a pseudo pulse generation circuit,
2 is an OR circuit, 3 is a phase / frequency detection circuit, 4 is a motor for rotating a disk (not shown), a is a reproduced horizontal synchronizing signal, b is an output from the pseudo pulse generation circuit 1, and c is an OR.
Output from the circuit 2. In FIG. 2,
The waveforms (a), (b), and (c) correspond to the signals a, b, and c in FIG. 1, respectively.

Next, the operation of this embodiment will be described.
A reproduced horizontal synchronizing signal a reproduced from a disk (not shown) is input to the pseudo pulse generation circuit 1 and the OR circuit 2 respectively. The waveform of the reproduced horizontal synchronization signal a is as shown in FIG. 2A, and a predetermined cycle of the horizontal synchronization signal is T ₀ . For example, in the case of the NTSC system, T ₀ = 6
3.5 μsec. Also, in FIG. 2A, a broken line indicates a lack of the reproduced horizontal synchronizing signal, and in FIG. 2A, a state where four pulses are missing.

When such a reproduced horizontal synchronizing signal a is input to the pseudo pulse generating circuit 1, an output b has a waveform as shown in FIG. In other words, the pseudo-pulse generating circuit 1 is constantly detects the period of the reproduced horizontal synchronizing signal a is inputted, the result of the detection, the period above T _1, the playback horizontal sync signal is not input, and generates a pulse. The setting values of T _1, it is necessary to select the T _1> T _0.
This is because the pseudo pulse needs to be generated when the reproduced horizontal synchronization signal is truly lost.

Also, the set value of T _{1 is} a value to be determined according to the response of the motor circuit system. Because T
_{If 1} is very close to T ₀ , the rotation speed of the motor 4 becomes slow, and if the period of the reproduced horizontal synchronization signal a becomes T ₁ or more,
This is because the spurious pulse generation circuit 1 will generate spurious pulses even if they are not missing. Also, T ₁
Is extremely large compared to T ₀ , a pseudo pulse to be generated when a signal is lost is delayed, and in an extreme case, it is the same as generating no pseudo pulse. Because.

When a pseudo pulse is generated after T ₁ , the pulse is generated later than the predetermined period T ₀ , and the next second pseudo pulse is only T ₁ -T _0. Generate early so that T ₁ + T ₂ = 2 · T ₀ . By doing so, the position of the second pulse, since the position of a predetermined horizontal synchronizing signal, third and subsequent pulses, if generated in a period of T _0, becomes coincident with the predetermined period.

Next, when the reproduced horizontal synchronizing signal is input to the pseudo pulse generating circuit 1 again, the pseudo pulse generating circuit 1 stops generating the pseudo pulse. Then again, if the incoming reproduced horizontal synchronizing signal is above T _1, to detect or not.
If the above T ₁ reproduced horizontal synchronizing signal is not incoming, the pseudo-pulse generating circuit 1 generates a pseudo pulse again, thus repeating the same operation as described above.

Next, as shown in FIG. 1, the OR circuit 2 inputs the reproduced horizontal synchronizing signal a and the pseudo pulse from the pseudo pulse generating circuit 1 and derives the logical sum of the two signals. ) Is output. Next, the phase / frequency detection circuit 3 receives the output c from the OR circuit 2 and the reference horizontal synchronizing signal, compares the phase and frequency between the two, and uses the comparison output to determine the rotation of the motor 4. Control.

As described above, even if the reproduced horizontal synchronizing signal is lost, the pseudo pulse from the pseudo pulse generating circuit 1 is interpolated, and a pulse is generated from the OR circuit 2 at a cycle of substantially T _0. The comparison output from the frequency detection circuit 3 is input to the motor 4 without largely changing. That is, even if the reproduced horizontal synchronizing signal is lost for a long time, the reproduced horizontal synchronizing signal as an input to the phase / frequency detection circuit 3 has the period T ₀ , so that the rotation of the motor 4 is maintained as it is. . Therefore, when the reproduction horizontal synchronizing signal a returns to the normal state again, the rotation of the motor 4 can immediately return to the predetermined rotation, and the return time can be extremely shortened as compared with the related art.

The pseudo pulse is generated only when the number of revolutions of the motor 4 has almost reached a predetermined value.
When the number of revolutions is largely shifted, it is necessary to stop the generation of the pulse. Because, when the rotation speed of the motor 4 is largely deviated, the period of the reproduction horizontal synchronization signal a is also greatly deviated from the predetermined period T ₀ , and in order to return the rotation of the motor 4 to the predetermined rotation speed, Phase / frequency detection circuit 3
Must be compared with the reference horizontal synchronization signal using only the reproduced horizontal synchronization signal a.

If a comparison is made using a pseudo pulse, since the period of the pseudo pulse is substantially T ₀ , it substantially matches the reference horizontal synchronization signal, and the phase / frequency detection circuit 3
This is because it is mistaken that the rotation of the motor 4 has returned to the predetermined rotation speed, and it is difficult to quickly return the rotation of the motor 4 to the predetermined rotation speed.

[0019]

According to the present invention, in a rotation control device for a motor for controlling the rotation of a disk, even if a reproduction horizontal synchronizing signal to be input is lost, a pseudo pulse is generated at a predetermined period during the loss period. Since the missing part is interpolated, the motor speed does not change during the missing period, and the motor speed can be kept constant regardless of the length of the missing period or the magnitude of the motor inertia. Therefore, there is an effect that the recovery when the reproduction horizontal synchronization signal returns to the normal state is extremely quick.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of an embodiment of the present invention.

FIG. 2 is a waveform chart showing a main part signal waveform in the circuit of FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pseudo pulse generation circuit, 2 ... OR circuit, 3 ... Phase and frequency detection circuit, 4 ... Motor

Claims (1)

(57) [Claims] A pseudo-pulse generating circuit for generating a pseudo-pulse in accordance with a generation state of a reproduction horizontal synchronization signal generated depending on the rotation of the motor; and a reproduction horizontal synchronization signal generated depending on the rotation of the motor. An OR circuit that outputs a logical sum of the output from the spurious pulse generation circuit and a phase and frequency of an output from the OR circuit and a reference horizontal synchronization signal that is separately supplied; And a control circuit for controlling the rotation of the reproduction horizontal synchronizing signal.
The first pseudo pulse generated first when falling
After the last occurrence of the horizontal synchronization signal, the reference horizontal synchronization signal
Occurs after a certain period of time longer than the period by Δt, and
The generated second pseudo pulse is referred to as the first pseudo pulse.
Occurs, the length Δ
occurs after a period of time that is short by t,
The generated pseudo pulse is defined as the period of the reference horizontal synchronization signal.
Motor rotation control device characterized by occurrence at the same period
(Where Δt is a length shorter than the period of the reference horizontal synchronization signal)
).