JPH0511473B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to rotational phase control of a video signal recording device.

Configuration of conventional examples and their problems In a video signal recording device, such as a video floppy, when a disk-shaped magnetic sheet is rotated by a motor and a video signal is recorded on the magnetic sheet, as shown in FIG. Phase relationship between the yoke (PG yoke) of the rotary pulse generator (hereinafter referred to as PG) that represents the rotational phase of the magnetic sheet and the leading edge of the vertical synchronization signal (hereinafter referred to as V _syoc ) of the video signal recorded on the magnetic sheet The format requires that the data be recorded while maintaining it at a predetermined angle θ (9.6°±2.7°).

Therefore, the PG attached to the magnetic sheet
The rotational _position of
It is determined by the positional relationship between the PG signal detector and the recording head that records the video signal. ), it is necessary to record the video signal while maintaining the That is, if a recording gate signal is generated at a predetermined timing from a PG signal that maintains this phase relationship, a recording format as shown in FIG. 1 can be realized. Furthermore, sufficiently high control accuracy is required for magnetic sheet rotation speed control, which normally has a narrow tolerance range for θ.

For this reason, in a video signal recording device such as a video floppy device, the rotation of a rotating recording medium (magnetic sheet) driven by a motor or the like is controlled by controlling the rotation speed in order to increase the control accuracy. In addition, phase control is performed to match the rotational phase to a predetermined relationship with the reference phase.At the same time, PG is used as the signal indicating the rotational phase, _Vsyoc is selected as this phase reference signal, and the rotational position of PG and _{Vsyoc are}
The above two requirements are satisfied by keeping the phase relationship at a predetermined value.

This conventional control method will be explained based on FIG. 2.

First, the speed control means will be explained. Motor 1
A speed comparison circuit 3 compares the output signal of a signal generating means proportional to the rotational speed of, for example, a frequency generator 2 (hereinafter referred to as FG) and the frequency of the speed reference signal,
Outputs a signal according to the frequency difference. When the frequency of the output of FG2 is higher, it outputs a signal that reduces the motor's rotational speed, and when it is lower, it outputs a signal that increases the motor's rotational speed, thereby keeping the motor's rotational speed constant. can be kept. Next, the phase control means will be explained. A phase comparator circuit 6 compares the output signal of a rotational phase detector of a rotary recording body driven by a motor 1, such as PG4, and the phase of a phase reference signal obtained by a synchronization signal generation circuit 5, and calculates the phase difference. A corresponding signal is output, and the motor 1 is rotated so that the phases of the phase reference signal and the PG signal are aligned. By combining the speed control means and phase control means as described above,
The rotational phase of the rotating recording medium and the phase of the phase reference signal were matched to a predetermined relationship, and highly accurate rotational control was realized.

After the rotational phase and the phase of the phase reference signal reach a predetermined relationship, a video signal is recorded by a recording gate signal generated at a predetermined timing from a signal indicating the rotational phase or from the phase reference signal.

However, this method has the following problems in video signal recording devices such as video floppy devices. For example, when recording one field of an NTSC video signal on a disk-shaped magnetic sheet in one rotation, the rotational speed is kept at 60 [rps], and the rotational phase of the rotating recording body is set in a predetermined relationship with the phase of the reference signal. It is necessary to control it to maintain it. Usually, V _syoc is used as the reference signal of the phase comparison circuit 6 of the phase control mentioned above,
V _syoc is 60 [Hz], and phase comparison is performed every time a PG signal is generated, so the sampling frequency for phase comparison (hereinafter referred to as _s ) is 60 [Hz].
In order for the control system to work stably, the cutoff frequency (hereinafter referred to as _c ) must be set to 1/10 or less of _s , taking into account the effects of phase delay due to phase comparison sampling, so in this case _c is
It becomes less than 1/10 of the frequency of V _syoc , that is, less than 6 [Hz]. By the way, the control system pull-in time at startup takes longer as _c is lower, and in fact _c is 6 [Hz].
If it is only a short amount of time, it will last for more than 1 second. To increase _c , _s must be increased, but in this case, _s is limited by the frequency of V _syoc , so it is difficult to shorten the phase control pull-in time at startup. Ta.

In particular, in a device that starts the motor immediately before recording a signal to reduce current consumption, the phase control pull-in time at startup, that is, the rotational phase of the rotating recording body and the phase of V _syoc after startup, is A major challenge has been to shorten the time it takes to establish a predetermined relationship and become ready for recording.

Purpose of the Invention The present invention solves the above-mentioned conventional problems.
The purpose of this invention is to shorten the pull-in time required to bring the rotational phase of a rotating body into a predetermined relationship with the phase of a phase reference signal at the time of startup.

Structure of the Invention A rotational phase detection means that is generated every rotation period of a rotational recording body and detects a rotational phase of the rotational recording body; a first synchronization signal generation means capable of setting a synchronization signal; a recording control means for generating a recording timing signal for recording a video signal in a predetermined format from the output of the rotational phase detection means or the synchronization signal; rotational speed detection means for outputting the rotational speed of the recording body as a frequency signal proportional to the speed; and rotational speed control for controlling the rotational speed of the rotational recording body to a predetermined speed based on the output of the rotational speed detection means. and a second synchronization signal that outputs a phase reference signal having the same frequency as the signal obtained from the rotational speed detection means when the rotating recording body rotates at a predetermined number of rotations, or a frequency obtained by dividing the frequency by N. generating means; when the rotating recording body rotates at the predetermined speed, the phases of the phase reference signal and the output signal of the rotational speed detecting means or a signal obtained by dividing the output by N are compared, and a predetermined phase relationship is obtained; a phase control means for controlling the rotation of the rotary recording body so that the rotation speed of the rotary recording member is adjusted so that the phase relationship between the phase reference signal and the output signal of the rotational speed detection means or the N-divided signal is reduced; After the phase entrainment detection signal is output by the phase entrainment detection means, the output of the rotational phase detection means or a signal obtained by delaying the output by a predetermined time is used as the external signal, and the first The video signal recording device sets the synchronization signal generating means to the reference phase at least once.

DESCRIPTION OF EMBODIMENTS In the present invention, in order to maintain a predetermined relationship between the rotational phase of a rotating recording medium driven by a motor or the like and the phase of a signal serving as a reference for this rotational phase, a speed control means and a phase control unit are used. and means for setting the means for generating a synchronizing signal for recording a video signal in a predetermined phase relationship with the rotational phase of the rotary recording member. The key point of the present invention is that the rotation control of a rotating recording medium is performed using speed control and phase control in order to improve control accuracy, as in the past, but phase control is performed using a rotation detector such as a PG that indicates the rotational position and V _syoc.
Rather than comparing the phase with the FG signal, the phase of the speed detection signal (FG signal) when the rated rotational speed is reached or the signal obtained by dividing it by N is calculated using the same stable frequency obtained from the original oscillation, etc. Compare the phase of the signal (hereinafter referred to as phase reference signal) with the signal of the same frequency as that signal (hereinafter referred to as phase reference signal).
The point is that phase control is performed so that they have a predetermined phase relationship by comparing the phases of
Since the phase relationship between PG and V _syoc is not uniquely determined,
After the rotation has stabilized, the synchronous signal generator is set (reset) using the PG signal so that PG and _Vsyoc have a predetermined phase relationship. Therefore, V _syoc is not involved in phase control of the rotating body. An embodiment of the present invention will be described with reference to FIG.

First, the operation of the speed control means is similar to the conventional device, in which the speed comparison circuit 10 compares the output proportional to the rotational speed of the motor 8, that is, the output of the FG 9, and the frequency of the speed reference signal. It drives the motor 8 and keeps the rotational speed constant.

Next, the operation of the phase control means will be explained. As the sampling signal of the phase comparator circuit 11, a signal obtained by dividing the output signal of the FG by N in the N frequency dividing circuit 12 (N≧1, N=1 represents the case where the frequency is not divided) is used, and as the phase reference signal. The output of the second synchronization signal generation circuit 13 is used. Here, FG generates Z pulses for each rotation of the rotating recording medium, and the rotating recording medium generates n pulses.
When rotating at [rps], the frequency _r of the phase reference signal
[Hz] must satisfy the relationship _r =Z×n÷N (where n corresponds to the frequency of PG). The phase comparison circuit 11 compares the phase relationship between the output of the N frequency divider circuit 12 having the above relationship and the phase reference signal, and controls the rotation of the motor 8 so that the phases have a predetermined relationship. At this time, it cannot be said that the vertical synchronization signal (V _syoc ) output from the first synchronization signal generation circuit 15 and the rotational phase of the rotary recording medium have a predetermined relationship. Here, it goes without saying that if _r is higher than the frequency of V _syoc , the time required to bring the phases into a predetermined relationship can be reduced compared to conventional devices.

By the way, when recording video signals on a rotating recording medium driven by a motor or the like in the format shown in Figure 1, the phases of the PG signal and _Vsyoc must be in a predetermined relationship. In the example, the PG signal and V _syoc are not considered at all by simply using the speed control means and the phase control means, so the phase relationship between these two signals is not determined at all.
Therefore, by checking the output of the phase comparator circuit 11 with the phase pull-in detection circuit 14, it is detected that the phase of the phase reference signal and the output of the N frequency divider circuit 12 have a predetermined relationship. The first synchronizing signal generating circuit 15 is reset using the PG signal or a signal obtained by delaying this PG signal by a predetermined time so that the phase of V _syoc has a predetermined relationship with the phase of the PG signal. As a result, the first synchronization signal generation circuit 1
5 can be forced to have a predetermined relationship with the _phase of the PG signal.

Next, we will explain in detail the control method using this example when, for example, a rotating body is driven at a speed of 60 [rps] using an FG configured to generate 65 pulses every time the motor rotates once. Explain. The frequency of the FG signal is 3900 [Hz], and the signal obtained by dividing this frequency by 2 is used as the sampling signal of the speed comparison circuit. As a result
_s is 1950 [Hz]. Also, _c is less than 1/10 of _s ,
In other words, since it has to be 195 [Hz] or less, the pull-in time for speed control is about 30 [msec].

In addition, _c of the phase control means is usually determined by considering the phase margin and control margin of the control system, and the c of the speed control means.
It must be about 1/5 or less of _c , in this case
Must be kept below 39 [Hz]. Therefore,
_s of the phase comparator circuit is more than 10 times _c , that is, approximately
It needs to be 390 [Hz] or more, and here we will use the signal obtained by dividing the FG signal by 8 as the sampling signal, so _s will be 487.5 [Hz], and the phase reference signal will be the second synchronization signal. It shall be obtained from the signal generation circuit. As a result, the phase control pull-in time is 130
It will be about [msec]. In addition, rotation speed n = 60
[rps], number of pulses generated in one rotation of FG, Z=
65, N of frequency divider circuit, N = 8, phase reference signal, _r =
The following equation is satisfied between 487.5 [Hz] and 487.5 [Hz].

_r =Z×n÷N Next, the operation of the reference phase setting means will be explained. Here, the reference phase refers to the phase relationship between the PG signal and _Vsyoc necessary for recording a video signal in the format shown in FIG. This is a signal delayed by a predetermined time from the first PG signal after the phase pull-in detection circuit 14 detects that the phase control has been pulled in.
Output from the first synchronization signal generation circuit 15
This is to set V _syoc as the reference phase. In this case, since the frequency of the PG signal is 60 [Hz], the time required from detecting the phase pull-in to detecting the first PG signal and setting it as the reference phase is a maximum of 17 msec.

As a result, after turning on the motor, the PG signal
The phase pull-in time until the phase of V _syoc reaches a predetermined relationship can be set to about 180 [msec].

As described above, in this embodiment, the N-divided output of the FG signal is used as the sampling signal of the phase control means, so _s can be set without being limited to the frequency of V _syoc as in the conventional example. Therefore, _s can also be made higher than the frequency of 1/10 or less of the frequency of V _syoc as in the conventional example. Therefore, even if the time required to adjust the phases of the PG signal and V _syoc to a predetermined relationship is added, the pull-in time of the phase control means can be significantly shortened compared to the conventional method.

Here, as long as the phase reference signal and the phase of the N-divided signal of the FG signal have a predetermined relationship, the phase comparator circuit 11 determines that the rotating recording body deviates from the rated rotation (rotation speed of V _syoc period). Unless otherwise specified, the once established phase relationship between the PG signal and V _syoc will not change. If the phases of the phase reference signal and the N-divided signal of the FG signal deviate from the predetermined relationship due to a large disturbance, the phase reference signal and the N-divided signal of the FG signal deviate from the predetermined relationship, and the first By setting the synchronizing signal generating circuit 15 to the reference phase again, a predetermined phase relationship can be maintained.

As described above, according to this embodiment, the N of the FG signal is
A phase control means that sets the phase of the frequency-divided output and the phase reference signal obtained by the second synchronization signal generation circuit 13 into a predetermined relationship; detects that the phases have a predetermined relationship; A signal obtained by delaying this PG signal by a predetermined time is used to generate V _syoc .
By providing means for setting the synchronization signal generating circuit of the synchronous signal generating circuit to the reference phase at least once at the time of startup,
The rotational phase of the rotating recording medium and the phase of V _syoc can be brought into a predetermined relationship in a shorter time than conventionally.

Note that when it is detected that the phase reference signal and the sampling signal have a predetermined phase relationship, the first PG signal immediately after detection is used to set the first synchronization signal generation circuit 15 to the reference phase. However, if the phases of the phase reference signal and the sampling signal have a predetermined relationship, by setting the reference phase at least once with a PG signal other than the first PG signal immediately after detection, the difference between the PG signal and V _syoc can be adjusted. It goes without saying that the phases can be set in a predetermined relationship.
Furthermore, although the first synchronous signal generation circuit 15 and the second signal generation circuit 13 have a common source oscillation circuit,
Separate source oscillation circuits may be used.

Effects of the Invention With the video signal recording device of the present invention, at startup,
The time taken to bring the rotational phase of the rotary recording medium and the phase of V _syoc into a predetermined relationship can be significantly shortened. In particular, in devices that start the motor immediately before recording video signals in order to reduce power consumption, the time from starting the motor until it is ready for recording with high-precision rotation can be significantly shortened. , the practical effects of the present invention are enormous.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a track pattern of a video floppy, FIG. 2 is a block diagram of motor control of a conventional video signal recording device, and FIG. 3 is a diagram of motor control of a video signal recording device according to an embodiment of the present invention. It is a block diagram. 8...Motor, 10...Speed comparison circuit, 11...
... Phase comparison circuit, 13 ... Second synchronization signal generation circuit, 14 ... Phase pull-in detection circuit, 15 ... First
16... Reference phase setting signal generation circuit.

Claims (1)

[Scope of Claims] 1. A rotational phase detection means that detects a rotational phase of the rotational recording body that is generated every rotation period of the rotational recording body; a first synchronization signal generating means capable of setting a vertical synchronization signal in relation to a reference phase (reference phase); and generating a recording timing signal for recording a video signal in a predetermined format from the output of the rotational phase detection means or the synchronization signal; a recording control means for outputting the rotational speed of the rotating recording body as a frequency signal proportional to the rotational speed; and a rotational speed detecting means for outputting the rotational speed of the rotating recording body as a frequency signal proportional to the rotational speed; a rotational speed control means for controlling the rotational speed to a predetermined speed; and a phase reference signal having the same frequency as the signal obtained from the rotational speed detection means when the rotating recording body rotates at a predetermined rotational speed, or a frequency obtained by dividing the frequency by N. a second synchronizing signal generating means for outputting a second synchronizing signal generating means for outputting a second synchronizing signal generating means for outputting a second synchronizing signal generating means for outputting a second synchronizing signal generating means for outputting a second synchronizing signal generating means for outputting a second synchronizing signal; a phase control means for controlling the rotation of the rotating recording body so that a predetermined phase relationship is achieved by comparing the phase relationship between the phase reference signal and the output signal of the rotational speed detection means or the N-divided signal. and a phase entrainment detection means for detecting that the phase entrainment detection signal is outputted by the phase entrainment detection means, and after the phase entrainment detection signal is outputted by the phase entrainment detection means, the output of the rotational phase detection means or a signal obtained by delaying the output by a predetermined time is sent to the external device. A video signal recording apparatus characterized in that the first synchronizing signal generating means is set to the reference phase at least once. 2 After setting the first synchronization signal generation means to the reference phase, the phase pull-in detection means detects that the phase of the output of the rotational speed detection means or its N-divided output and the phase reference signal deviates from a predetermined relationship. In this case, the phase entrainment detection means detects that the predetermined phase relationship has been achieved again, and the first
2. A video signal recording apparatus according to claim 1, wherein said synchronizing signal generating means is set to said reference phase at least once.