JPS6243265B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information signal recording or reproducing apparatus suitable for optically recording video signals on a disk.

When optically recording a video signal on an unrecorded disk, a modulated light beam is projected onto the rotating disk and scanned in the form of concentric or spiral tracks. By the way, in order to equalize the recording state on the disk, it is necessary not only to simply rotate the disk at a constant speed, but also to perform phase control. Therefore, in the past, the disk motor was controlled by inputting the sum of the speed detection voltage and the phase comparison output voltage to a voltage comparison amplifier circuit and comparing this sum voltage with a reference voltage. However, if the speed detection circuit that obtains the voltage corresponding to the speed no longer generates a constant speed detection voltage at a constant rotation speed due to temperature changes or aging, the operating point in phase control will shift, and as a result, the phase A shift occurred.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a recording or reproducing apparatus that can be controlled with little phase shift.

To achieve the above object, the present invention includes a rotary drive device for rotating a recording medium, a head for recording or reproducing information signals including a synchronization signal, and a rotary drive device for rotating the recording medium between the recording medium and the head. a radial feed device for producing relative feed in the radial direction; a reference signal generation circuit for generating a reference signal corresponding to the synchronization signal; and a reference signal generation circuit for controlling rotation of the recording medium by the rotation drive device. For example, a control element such as the transistor 11 and a voltage corresponding to the difference between the reference voltage and the control voltage are obtained,
a comparison amplifier circuit that controls the control element so that the recording medium is in a predetermined rotational state; and a comparison amplifier circuit that detects the rotational speed of the recording medium from the recording medium or the rotational drive device and generates a voltage corresponding to the rotational speed. a stabilizing voltage supply circuit that supplies a voltage substantially equal to the output voltage of the speed detection circuit corresponding to a constant rotational speed of the recording medium, and a stabilizing voltage supply circuit that supplies a voltage substantially equal to the output voltage of the speed detection circuit corresponding to a constant rotational speed of the recording medium; a rotational position detection device that detects a fixed position from the recording medium or the rotation drive device; and a phase between the reference signal obtained from the reference signal generation circuit and the rotational position detection signal obtained from the rotational position detection device. a phase comparison circuit that performs a comparison and generates a voltage corresponding to a phase difference; a synchronization detection circuit that detects that the reference signal and the rotational position detection signal are synchronized; and a synchronization detection signal is generated from the synchronization detection circuit. Before this, a voltage that is the sum of the output voltage of the rotation speed detection circuit and the output voltage of the phase comparison circuit is supplied to the comparison circuit as the control voltage, and the stabilization voltage is adjusted in response to the generation of the synchronization detection signal. The present invention relates to a recording or reproducing apparatus comprising a selection switch circuit which supplies the sum of the output voltage of the supply circuit and the output voltage of the phase comparison circuit to the comparison circuit as the control voltage.

According to the present invention, after synchronization, the stabilizing voltage supply circuit is connected in place of the speed detection circuit, so phase control can be performed regardless of temperature changes or secular changes in the speed detection circuit. I can do it.

Hereinafter, a video signal recording apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

In the optical recording apparatus shown in FIG. 1, a turntable 2 and a DC motor 3 are provided as a rotation drive device for rotating a disk-shaped recording medium 1. Also, head 4 is shown surrounded by a dotted line.
includes a laser light source 5, an optical modulator 6, and a condenser lens 7. The NTSC video signal supplied from the video signal supply circuit 8 is converted into a frequency modulated wave by the frequency modulation circuit 9 and supplied to the optical modulator 6 . Therefore, a modulated light beam is projected onto the recording medium 1 from the head 4, and recording corresponding to the modulated light beam is generated. Since the head 4 is connected to the radial feed device 10, the head 4 is fed in the radial direction as recording progresses, creating a spiral track T on the recording medium 1 as shown in FIG. Although not shown, tracking is controlled by a rotating mirror placed in the light beam path. In this embodiment, a spiral track is formed by feeding the head 4, but a concentric track may also be formed, or a spiral or concentric track may be formed by feeding the recording medium 1 in its radial direction. A shaped track may also be formed.

In order to drive and control the recording medium 1 and the motor 3 at a constant speed, a transistor 11 is connected in series with the motor 3 as a control element for voltage adjustment. Further, in order to supply a servo control signal to this motor control transistor 11, a comparison amplifier circuit 12 is coupled to the base of this transistor 11. still,
This comparison amplifier circuit 12 compares a reference voltage source 13 that provides a reference voltage corresponding to a constant rotational speed with a control voltage obtained on an input line 14 and a differential amplifier that generates an output based on the difference. Amplifier 15
and an amplifier 16 that generates a servo control signal corresponding to the difference between the reference voltage and the control voltage.
supply to the base of

A speed detection circuit 17 for detecting the rotational speeds of the recording medium 1 and the motor 3 includes a speed detector 18 consisting of a frequency generator coupled to the motor 3, and a frequency generator 18 that corresponds to the speed obtained from the speed detector 18. It consists of a frequency-voltage converter 19 that converts a signal into a DC voltage, and an amplifier 20, and generates a DC control voltage corresponding to the rotation speed. Since the first selection switch circuit 21 is provided between the speed detection circuit 17 and the comparison amplifier circuit 12, the speed detection voltage is supplied to the comparison amplifier circuit 12 only while the switch circuit 21 is on.

22 is a stabilized voltage supply circuit, which includes a DC power supply E, a stabilization control transistor Q ₁ , voltage detection and division resistors R ₁ and R ₂ , a comparison and amplification transistor Q ₂ ,
It includes a reference Zener diode ZD and a resistor _R3 for passing a base current, and supplies a fixed voltage substantially equal to the output voltage obtained from the speed detection circuit 17 when the motor 3 is rotating at a constant rotational speed. Since the second selection switch circuit 23 is connected between the stabilized voltage supply circuit 22 and the comparison amplifier circuit 12, the stabilized voltage is supplied only while the switch circuit 23 is on. More specifically, since the first switch circuit 21 and the second switch circuit 23 are configured to operate in opposite directions, the second switch circuit 23 is turned on while the first switch circuit 21 is off. This provides a stabilized voltage, that is, a fixed voltage.

By the way, if the motor 3 is simply driven at a constant speed, only the control based on the output of the speed detection circuit 17 is sufficient. However, when controlling by considering the position of the recording medium 1 during one rotation, phase control must be performed. For this reason, the rotational position detection device 2
4 is provided. This rotational position detection device 24
includes a light emitting element 25, a light receiving element 26, and an amplifier 27, and detects passage through a reflective surface 28 provided at a fixed position on the back surface of the recording medium 1. In this embodiment, the recording medium 1 is provided with the reflective surface 28 as the detected portion, but the turntable 2 or the motor 3 may be provided at a constant circumferential position. Alternatively, the rotational position may be detected magnetically or electrically instead of optically.

The reference signal generation circuit 29, which generates a reference signal for comparison with the rotational position detection signal, generates a signal in one frame based on the vertical synchronization signal separated by the synchronization signal separation circuit 30 from the composite video signal obtained from the video signal supply circuit 8. It generates one pulse.
That is, one pulse is generated corresponding to one rotation of the recording medium 1.

Reference numeral 31 denotes a phase comparator circuit, which includes a phase comparator 32 connected to the reference signal generation circuit 29 and the rotational position detection device 24, a low-pass filter 33, and an amplifier 34, and is used to detect the difference between the reference signal and the rotational position detection signal. The phases are compared, a voltage corresponding to the phase difference is generated, and this is supplied to the comparison amplifier circuit 12.

A synchronization detection circuit 35 is coupled to the reference signal generation circuit 29 and the speed detection device 24, and detects that the reference signal and the rotational position detection signal are in phase synchronization. In this embodiment, as shown in FIG. 2, the synchronization detection circuit 35 is composed of a D-type flip-flop FF and a retriggerable monostable multivibrator MM, and the D input terminal is used for generating the reference signal shown in FIG. The clock input terminal CK is coupled to the rotational position sensing device 24. Therefore, in the asynchronous period, the
As shown before time t ₁ , pulses are generated intermittently at the Q output terminal, but when the synchronization state is reached, the reference signal and rotational position detection signal are repeatedly input at the same time, so the Q _output is It is kept at a high level as shown after the point in time. In this embodiment, in order to send out a synchronization detection signal after determining that the Q output is maintained at a high level for a certain period of time or more, a certain period synchronous joint determination circuit MM consisting of a retriggerable monostable multivibrator is used. is provided.

In FIG. 1, the output of the synchronization detection circuit 35 is transmitted to the first and second switch circuits 2 via a drive circuit
1 and 23 control terminals. Further, the synchronization detection circuit 35 is coupled to a recording start device 38 via a drive circuit 36 and a timing adjustment circuit 37. The recording starting device 38 includes a plunger solenoid 39 and a shutter 40, and is configured to remove the shutter 40 from the path of the recording light beam and start recording when the plunger solenoid 39 is activated in response to a synchronization detection signal. There is.

Next, the recording method and operation of the apparatus shown in FIG. 1 will be described. When forming a record on the recording medium 1, for example, the recording medium 1 having a photoresist layer is used.
is rotated by motor 3. At this time, the first switch circuit 21 is kept on and the second switch circuit 23 is kept off. As a result, the motor 3 and the recording medium 1 are speed-controlled, that is, frequency-controlled, to a constant rotational speed. At the same time, one pulse is generated from the rotational position detection device 24 for one rotation corresponding to a certain position of the recording medium 1, and this pulse is generated by the phase comparison circuit 31.
and becomes an input to the synchronization detection circuit 35. Further, a reference signal, that is, a frame synchronization signal based on a vertical synchronization signal separated from a video signal of, for example, a previous region of the video signal area to be recorded, which is supplied from the video signal supply circuit 8, is sent to the phase comparison circuit 32 and the synchronization detection circuit 3.
Enter 5. Even if the speed of the motor 3 is controlled by the output of the speed detection circuit 17, the phases of the reference signal and the rotational position detection signal do not necessarily match, so a phase comparison circuit is used to make this phase difference zero. The output voltage of 31 is superimposed on the speed detection signal voltage and is input to the comparison amplifier circuit 12. As a result, control is performed such that the phases of the reference signal corresponding to the vertical synchronization signal and the rotational position detection signal match, and after a short period of time has passed since the motor 3 is started, an in-phase synchronization state is achieved. When the synchronization state continues for a certain period of time determined by the monostable multivibrator in the synchronization continuation determination circuit MM shown in FIG. is generated, and after the time is adjusted as necessary by a timing adjustment circuit 37 consisting of a delay circuit, a voltage is applied to the plunger solenoid 39, and the shutter 40 is removed from the light beam path, making it possible to start recording. At this time, if a video signal has been supplied in advance and a modulated light beam has been generated in advance, recording will begin immediately. That is, the photoresistor is exposed to light corresponding to the modulated light beam. Further, the sending device 10 starts sending in response to the synchronization detection signal. Tracking control is also performed using a tracking beam, which is not shown.

Incidentally, since recording starts when the reference signal, that is, the vertical synchronizing signal, matches the fixed position on the recording medium determined by the reflective surface 28, even if recording is interrupted and recording is performed intermittently, the vertical synchronizing signal will not change. The positions can be aligned at fixed positions on the recording medium 1 as shown in FIG. In the example shown in FIG. 4, since recording starts when the detection signal of the reflective surface 28 and the reference signal (vertical synchronization signal) match, Synchronous signal recording areas Vs are arranged. Therefore, even if recording is interrupted, the seam does not shift.

As described above, when a synchronization detection signal is generated from the synchronization detection circuit 35 at the same time as recording is started, the first
The first switch circuit 21 is turned off, and the second switch circuit 23 is turned on. Therefore, a stabilized voltage, that is, a fixed voltage is supplied from the stabilized voltage supply circuit 22 instead of the speed detection voltage. The stabilizing voltage is determined by the speed detection circuit 1, which corresponds to a constant rotation speed under normal conditions.
Since the output voltage is set in advance to be substantially equal to the output voltage of No. 7, even if the first and second switch circuits 21 and 23 are switched, disturbances in motor control will not substantially occur. Further, even if the speed control is stopped, the phase control is continued, so the motor 3 and the recording medium 1 rotate at a constant rotational speed and under phase control. Therefore, it is ensured that the vertical synchronizing signal is recorded on a straight line in the radial direction of the disk-shaped recording medium 1.

Further, in this embodiment, the stabilized voltage supply circuit 22
For example, the temperature characteristics of the phase comparison circuit 31 are set to be opposite to those of the phase comparison circuit 31 due to the characteristics of the Zener diode ZD, so if the output voltage of the phase comparison circuit 31 increases due to a temperature change, for example, The output voltage of the stabilizing voltage supply circuit 22 decreases, the voltages cancel each other out, and no deviation in control occurs due to temperature changes. If control by the speed detection circuit 17 is continued and the specified output voltage cannot be obtained at a constant rotation speed due to a deviation due to temperature or aging, the operating point in phase control will be shifted, and as a result, the phase Misalignment occurs.

During recording under phase control based on the stabilizing voltage and phase comparison output, the synchronization detection circuit 35
When an asynchronous output is generated, the shutter 40 blocks the optical path and stops recording in the state of synchronization disturbance.

As is clear from the above, this embodiment has the following advantages.

(b) After synchronization is detected, a stabilized voltage is supplied from the stabilized voltage supply circuit 22, so even if the detected voltage changes due to temperature changes or aging in the speed detection circuit 17, this will not affect the detection voltage. Phase control can be performed independently.

(b) The stabilized voltage supply circuit 22 is configured to obtain a stable voltage, and the phase comparator circuit 31
Since the characteristics are such that they cancel out the temperature characteristics caused by temperature changes, it is possible to limit phase shifts due to temperature changes.

(c) Since the rotational position detection device 24 is provided and the recording start device 38 is activated to start recording when synchronized with the reference signal, that is, the frame synchronization signal, the recording area of the vertical synchronization signal can be maintained even after recording is interrupted. can be aligned at a certain angle. Therefore, the image will not be distorted during playback.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto and can be further modified. For example, instead of configuring the speed detector 18 with a frequency generator, detecting parts such as reflective surfaces or holes are provided at regular intervals on a rotating disk coupled to the recording medium 1 or the turntable 2 or the motor 3, and the A frequency signal corresponding to the speed may be obtained by, for example, optically detecting the speed. Therefore, the reflective surface 28 for detecting rotational position may also be used for speed detection.

Furthermore, synchronization detection may be performed based on the output of the phase comparator 32 without providing the synchronization detection circuit 35 independently. In addition, rotational position detection is performed on the recording medium 1.
Alternatively, a magnetic material may be placed on a turntable or the like, and magnetic pickup may be used. In addition, the recording medium 1 or the turntable 2 is provided with detection parts such as reflective surfaces 28 at two locations 180 degrees apart, and the reference signal generation circuit 29 also generates a reference signal synchronized with the vertical synchronization signal for each field. It's okay.

In addition, the detected part for detecting the rotational position is not aligned with the vertical synchronizing signal recording area, but a reflective surface 28a is provided at a part having an angular difference of 90 degrees from the vertical synchronizing signal recording area Vs, as shown in FIG. 4, for example. It's okay.
In such a case, a phase shift circuit is provided in the reference signal generation circuit 29 or the rotational position detection circuit 24 or the like to electrically adjust the phases of the phase comparison circuit system and the synchronization detection circuit system. Further, the position of the reflecting surface 28a may be moved away from the vertical synchronizing signal recording area Vs by an amount corresponding to the response delay. Furthermore, the synchronization detection circuit 35 may not be configured to detect in-phase synchronization, but may instead be configured to detect a state of synchronization at different phases. In short, even if there is an angular difference between the synchronizing signal recording area and a fixed position in the rotational direction, the object of the present invention can be achieved if the angular difference is controlled to always be kept constant.

Furthermore, two rotational position detection devices 24 and two reference signal generation circuits 29 may be provided instead of being shared by the phase comparison circuit 31 and the synchronization detection circuit 35.

Moreover, it is applicable not only to optical recording but also to, for example, magnetic recording.

Further, the stabilized voltage supply circuit 22 may be a transistor stabilized power supply circuit in which a differential amplifier circuit including a pair of transistors forms a comparison amplifier circuit. Further, in order to obtain a temperature characteristic opposite to that of the phase comparator circuit 31, a thermistor or the like may be incorporated in the stabilizing voltage supply circuit 22.

Furthermore, the recording start device 38 may not be configured to control the shutter 40, but may be configured to control the light source 5, the optical modulator 6, the video signal supply line, or the like.

Furthermore, the present invention is not limited to recording video signals;
For example, it can be applied to recording audio PCM signals.

It is also applicable to playback devices. In the case of a playback device, a detection portion such as the reflective surface 28 is provided on the recording medium 1 or the turntable 2 so as to have a certain positional relationship with the vertical synchronization signal recording area of the video signal recorded on the recording medium 1. . It also generates a reference signal of a frequency corresponding to the frame synchronization signal during normal playback. In the case of optical reproduction, an unmodulated light beam is projected onto a recording medium, and a light beam modulated by recording is detected. Alternatively, a switch may be provided on the reproduction output transmission path, and the switch may be configured to be turned on by a synchronization detection signal, thereby cutting the reproduced image during the asynchronous period.

[Brief explanation of the drawing]

1 is a block diagram showing a recording apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing the synchronization detection circuit of FIG. 1, and FIG. 3 is a waveform diagram showing the output of the flip-flop of FIG. 2. FIG. 4 is a plan view illustrating the recording medium of FIG. 1. In the symbols used in the drawings, 1 is the recording medium, 3 is the motor, 4 is the head, 8 is the video signal supply circuit, 1
0 is a sending device, 11 is a transistor, 12 is a comparison amplifier circuit, 17 is a speed detection circuit, 21 is a first selection switch circuit, 22 is a stabilizing voltage supply circuit, 2
3 is a second selection switch circuit, 24 is a rotational position detection device, 29 is a reference signal generation circuit, 31 is a phase comparison circuit, 35 is a synchronization detection circuit, and 38 is a recording start device.

Claims (1)

[Scope of Claims] 1. A rotary drive device that rotates a recording medium, a head for recording or reproducing information signals including a synchronization signal, and a radial direction of the recording medium between the recording medium and the head. a radial feed device for producing relative feed; a reference signal generation circuit for generating a reference signal corresponding to the synchronization signal; a control element for controlling rotation of the recording medium by the rotary drive device; a comparison amplifier circuit that obtains a voltage corresponding to a voltage difference between a reference voltage and a control voltage and controls the control element so that the recording medium is in a predetermined rotational state; or a speed detection circuit that detects from the rotational drive device and generates a voltage corresponding to the rotational speed, and supplies a voltage substantially equal to the output voltage of the speed detection circuit that corresponds to a constant rotational speed of the recording medium. a stabilizing voltage supply circuit; a rotational position detection device for detecting a fixed position in the circumferential direction of the recording medium being rotationally driven from the recording medium or the rotational drive device; A phase comparison circuit that performs a phase comparison between a reference signal and a rotational position detection signal obtained from the rotational position detection device and generates a voltage corresponding to a phase difference, and the reference signal and the rotational position detection signal are synchronized. a synchronization detection circuit that detects the synchronization detection circuit; and before the synchronization detection signal is generated from the synchronization detection circuit, the comparison circuit uses a sum of the output voltage of the rotational speed detection circuit and the output voltage of the phase comparison circuit as the control voltage. a selection switch circuit that supplies, as the control voltage, a voltage that is the sum of the output voltage of the stabilizing voltage supply circuit and the output voltage of the phase comparison circuit to the comparison circuit in response to generation of the synchronization detection signal; A recording or reproducing device consisting of: 2. The recording or reproducing device according to claim 1, wherein the stabilized voltage supply circuit is a circuit that supplies a stabilized voltage with a temperature characteristic opposite to that of the output voltage of the phase comparison circuit. .