JPH07225990A - Phase control device - Google Patents

Abstract

PURPOSE:To prevent the generation of a screen-flowing at the time of reproducing pictures by making the rotational deviation of a cylinder small by delaying a phase pull-in while changing values of limitters even though the VSNC of a recording are discontinuous in a recording. CONSTITUTION:A pulse generator 2 generating pulses PG corresponding to the rotational phase of a cylinder and a frequency generator 3 generating pulses FG having a frequency corresponding to the rotational speed of a cylinder motor 1 are fitted to the vicinity of the rotary shaft of the cylinder motor 1. Wave forms of pulses PG and FG are respectively shaped by respective schmitt circuits 4, 5 to be supplied to a phase detector 7 and a speed detector 8. The phase detector 7 detects a deviated quantity from the reference phase of pulses PG and controls the rotational phase of the cylinder motor 1 with a phase differential signal. The speed detector 8 detects a deviated quantity from the constant period of pulses FG to output a speed differential signal for controlling the rotational speed of the motor 1 and supplies it to one end of input ends of a composite circuit 10.

Description

Detailed Description of the Invention

[0001]

[Industrial applications]

The present invention relates to a phase control device in a rotary cylinder of a magnetic recording / reproducing apparatus.

2. Description of the Related Art Conventionally, a home magnetic recording / reproducing apparatus (hereinafter referred to as V
(TR)), when recording / reproducing on / from a magnetic tape, the rotational speed of the cylinder, that is, the rotational speed and rotational phase of the rotary magnetic head, the tape traveling speed, that is, the rotational speed of the capstan motor, etc. are set as desired. A servo mechanism is provided for controlling.

Generally, this servo mechanism has a role of detecting how much the controlled object is from the target and reducing the deviation until it disappears, and the number of rotations and phase (rotation angle) of each motor. Is always compared with the reference, and the motor is moved in the direction of eliminating the error.

Therefore, in such a servo mechanism, speed control or phase control of the cylinder motor and capstan motor plays an important role especially at the time of recording / reproducing of the VTR and, at the same time, an ideal servo. That is, it is desirable to perform ideal phase control.

By the way, the reference signal in the phase control of the cylinder motor and the capstan motor is the vertical synchronization in the cylinder motor during the recording mode and the editing mode (in this case, indicating the run-up period at the time of connection). It is a signal (hereinafter referred to as VSYNC) and is an internal reference signal in the reproduction mode.

Further, the reference signal for phase control of the capstan is an internal reference signal in the recording mode and, for example, VHS in the edit mode and the reproduction mode.
Alternatively, in the case of the β method, it is a CTL signal.

Therefore, by using these reference signals, the speed control of each motor, that is, the phase control can be performed.

On the other hand, when such a reference signal is used and the phase control at the time of recording is taken into consideration, this phase control controls the phase of the cylinder to record VSYNC at a fixed position and, for example, a plurality of cylinders. A pulse signal for switching the signal of the rotary head provided is compared with VSYNC, and a voltage for correcting an error is applied to the motor that rotates the cylinder.

A device (FG, Frequency) for generating a signal of a frequency corresponding to the rotation speed to the motor.
(Generator) is provided, a signal delayed by one cycle is created, this signal is measured without delay, and the error is detected, and the voltage necessary for correction is applied to the motor from this error. In this way, speed control is performed.

FIG. 3 shows a conventional phase control device having such a configuration. FIG. 3 is a block diagram showing a conventional phase control device.

In FIG. 3, a cylinder motor 1 is a motor for rotationally driving a cylinder motor equipped with a magnetic head, and a pulse for generating a pulse PG corresponding to a cylinder rotation phase is provided in the vicinity of the motor rotation shaft. A generator 2 and a frequency generator 3 that generates a pulse FG having a frequency corresponding to the rotation speed of the cylinder motor 1 are attached.

The pulse PG and the pulse FG are waveform-shaped by the Schmitt circuits 4 and 5, and are supplied to the phase detector 7 and the speed detector 8. The phase detector 7 has a pulse P
The amount of deviation of G from the reference phase is detected, and the cylinder motor 1
It outputs a phase difference signal for controlling the rotational phase of the. Further, the speed detector 8 detects a deviation amount of the pulse FG from a certain cycle and outputs a speed difference signal for controlling the rotation speed of the cylinder motor 1.
The speed difference signal from the speed detector 8 is supplied to one input end of the synthesizing means 10. The phase difference signal output from the phase detection circuit 7 and limited by the limiter 9 is input to the other input terminal of the synthesizing means 10.

The synthesizing means 10 adds the phase difference signal and the velocity difference signal, and the addition output is the filter 11
And is output as a control signal for the rotation phase and the rotation speed. Then, it is amplified by the amplifier 12 and supplied to the control winding of the cylinder motor 1 via the driver circuit 13.

By the way, when the phase control apparatus as described above is used, for example, VSYNC may be discontinuously recorded when switching to a channel of a local station or the like during recording. In this case, if the data obtained by comparing the phases of the pulse PG and VSYNC are out of phase by a certain value or more, for example, the data becomes a certain value determined by the circuit or system, and the speed of the pulse FG is detected. The signal thus obtained, that is, the speed difference signal, is added, and the motor rotates while deviating from the normal speed until the phase is pulled in, as shown in FIG. 4B.

Therefore, the conventional problems in such a case will be described with reference to FIG.

FIG. 4 is an explanatory diagram showing the characteristics of the conventional phase control device at the time of recording, FIG. 4 (a) shows the tape pattern at the time of recording, and FIG. 4 (b) shows the rotation deviation and frequency of the cylinder. It shows the deviation.

In FIG. 4, for example, as described above,
When the VSYNC of the recording signal is discontinuous during recording, by having the discontinuous portion of VSYNC as shown in FIG. 4B, the rotation deviation of the cylinder becomes large in this range. It was As a result,
As shown in (a), the recording tape pattern is recorded at a different VSYNC recording position due to a change in the recording signal, that is, the VSYNC phase is shifted.

Therefore, when the magnetic tape recorded in this way is reproduced, for example, the cylinder rotation deviation at the time of recording is the horizontal synchronization signal at the time of reproduction (hereinafter referred to as HSY).
(Notated as NC) and the frequency deviation of the color signal, as shown in FIG. 4B, the phase pull-in becomes faster and the cylinder rotation deviation becomes larger. Therefore, on the television side, HSYNC cannot be drawn in, that is, the screen flows, and also on the VTR side, color signal processing cannot be performed, resulting in color misregistration or color disappearance. was there.

Further, normally, when the inertia of the cylinder is large, the phase pull-in is delayed, so the above-mentioned problem does not occur, but if the phase pull-in time is long, the reproduction from the cylinder stop until the image is output. However, there is a problem in that it takes time to start recording when recording after the cylinder is stopped.

However, there is a drawback in that the latter problem is solved but the former problem is not solved if the inertia of the cylinder is light and the retracting is quick.

[0021]

As described above, in the conventional phase control device, the phase pull-in, that is, the phase control corresponding to the recording / reproduction when the VSYNC of the recording signal becomes discontinuous during recording is performed. I couldn't.

Therefore, the present invention has been made in view of the above problems, and even if the VSNC of the recording signal becomes discontinuous during recording, recording can be performed without causing screen drift or color distortion during reproduction, and It is an object of the present invention to provide a phase control device capable of speeding up image output during reproduction at times other than recording.

[0023]

A phase control apparatus according to the present invention according to claim 1 corresponds to a first signal detecting means for obtaining a speed signal corresponding to a rotation speed of a cylinder motor, and a rotation phase of the cylinder motor. Second signal detecting means for obtaining the phase signal, speed detecting means for detecting a speed difference signal between the speed signal and the target rotation speed of the cylinder motor, and the phase signal and the target rotation phase of the cylinder motor. Phase detection means for detecting the phase difference signal, switching means for switching the phase difference signal from the phase detection means by a control signal according to each mode, and phase difference signal switched by the switching means for each mode. First and second limiters for limiting the phase difference signals to correspond to each other, and the phase difference signal from the first or second limiter Synthesizing means for synthesizing the degree difference signal, characterized by comprising a means for driving the cylinder motor in addition a DC voltage of a predetermined value corresponding to the combined output from said combining means.

According to a second aspect of the phase control device of the present invention, in the phase control device according to the first aspect, the limit value of the first limiter is set smaller than the second limiter limit value, and the switching means is set. The first limiter is selected during recording, and the second limiter is selected in other modes.

[0025]

According to the present invention, even if the VSNC of the recording signal is discontinuous during recording, the limiter value is changed to delay the phase pull-in and reduce the cylinder rotation deviation to reduce the screen flow or color during reproduction. It is possible to perform recording that prevents the occurrence of disorder. In addition to the recording mode, the switching unit switches to the second limiter to accelerate the phase pull-in, thereby shortening the image output time and the like.

[0026]

EXAMPLES Examples will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a phase control device according to the present invention, and the same components as those in FIG. 4 are designated by the same reference numerals.

In FIG. 1, a cylinder motor 1 is a motor for rotationally driving a cylinder motor equipped with a magnetic head, and a pulse for generating a pulse PG corresponding to the cylinder rotation phase is provided in the vicinity of the motor rotation shaft. A generator 2 and a frequency generator 3 that generates a pulse FG having a frequency corresponding to the rotation speed of the cylinder motor 1 are attached.

The pulse PG and the pulse FG are waveform-shaped by the Schmitt circuits 4 and 5, and are supplied to the phase detector 7 and the speed detector 8. The phase detector 7 has a pulse P
The amount of deviation of G from the reference phase is detected, and the cylinder motor 1
It outputs a phase difference signal for controlling the rotational phase of the. Further, the speed detector 8 detects a deviation amount of the pulse FG from a certain cycle and outputs a speed difference signal for controlling the rotation speed of the cylinder motor 1.
The speed difference signal from the speed detector 8 is supplied to one input end of the synthesizing means 10.

On the other hand, the phase difference signal output from the phase detection circuit 7 is supplied to the switch SW1. The switching signal generating means 14 supplies a switching signal for switching SW1 to correspond to each mode to the switch SW1.
For example, in the recording mode, the switching signal causes H
Is selected and supplied to the other input end of the combining means via the first limiter 9a. Further, in the reproduction / edit mode, L is selected and supplied to the input end of the synthesizing means via the second limiter 9b. Therefore, the phase detection circuit 7
The phase difference signal output from the first and second phase difference signals corresponding to each mode is switched by the switching signal.
The phase difference signal is limited by the limiters 9a and 9b.

The synthesizing means 10 adds the phase difference signal and the speed difference signal, and the addition output is the filter 11
And is output as a control signal for the rotation phase and the rotation speed. Then, it is amplified by the amplifier 12 and supplied to the control winding of the cylinder motor 1 via the driver circuit 13. Further, in the present embodiment, the filter 11
Is configured so that a DC voltage Vdc having a predetermined value can be applied to the output of, that is, the rotation speed of the cylinder motor 1 is changed.

In the phase control device having such a configuration, the phase difference signal from the phase detector 7 is selected by the switch SW1 corresponding to each mode, and the two phase difference signals are selected so that the phase difference signal corresponds to the mode. The limiters 9a and 9b are characterized by setting different limiter values respectively.

Next, the operation of the phase controller having such a configuration will be described in detail.

In FIG. 1, the speed detector 8 detects the speed difference signal from the pulse FG output from the frequency generator 3, and the phase detector 7 outputs the pulse PG output from the pulse generator 2 and the VSYNC oscillator 6. Output from VSYNC
The phase difference signal is detected by comparing and. The switch SW1 switches the phase difference signal to the H level or the L level according to each mode by the switching signal from the switching signal generating means 15. For example, when recording, the level is switched to the H level, and when reproducing / editing, the level is switched to the L level. The first and second limiters 9a,
9b limits the phase difference signal input according to each mode to a predetermined level.

The phase difference signal thus obtained and the speed difference signal from the speed detector 8 are added by the synthesizing means 10. The addition result is integrated by the filter 11 and input to the amplifier 12 as a rotation control signal. Amplifier 12
Is a driver circuit 13 that amplifies the input rotation control signal.
Output to the cylinder motor 1 via. Further, Vdc is applied to the output of the filter 11, that is, the rotation speed control signal, and output to the cylinder motor 1.

In the phase control device controlled in this way,
When the phase difference between VSNC and the pulse PG is large, the phase difference signal, that is, the phase error is limited by the limiters 9a and 9b. In this sense, if the output of the speed detector and the output of the phase detector when the phase is normally drawn are set to 0, then the cylinder motor 1 will rotate at a speed determined by Vdc.

For example, when the phase error is large and the phase error becomes the limiter value R> 0, the value after adding the speed error becomes R, and Vdc + R (assuming filter gain = 1) is applied to the cylinder motor 1. And it rotates quickly.
Therefore, the speed detector 8 decelerates and outputs -R '. After that, Vdc + RR ′ is applied to the cylinder motor 1. Therefore, when the gains of the cylinder motor 1 and the speed detector 8 are set to 1, that is, when the voltage applied to the motor changes by ΔV = R, the speed detector outputs -R, and the variation RR 'of the motor applied voltage becomes Equal to the sign of the velocity detector output -R 'is reversed. That is, R-R '=-(-R'), Therefore, when the phase detector outputs a fixed value R, the motor is That is, by changing the limiter value of the output of the comparison detector, the rotation fluctuation amount when the position is pulled in is determined.

Therefore, in this embodiment, the switch SW1 is switched depending on each mode to change the limiter value. For example, if the limit value of the second limiter 9b (hereinafter referred to as limiter level) connected to this is switched to L level during reproduction / editing, for example, Y, this limiter level Y is the same as the conventional limiter 9a.
Set to a value that is greater than the level of and the phase pull-in is fast. Further, at the time of recording, when the level is switched to the H level and the limiter level of the first limiter 9a connected thereto is X, for example, this limiter level X is smaller than the limiter level Y, and this limiter level is the speed. The speed deviation between when it is added to the detection signal and when it is not added is set to a value within about 1%.

Next, a more detailed description will be given with reference to FIG. FIG. 2 shows an embodiment in which the limiter level is set to X during recording by the phase control device according to the present invention, and FIG. 2A is an explanatory diagram showing a recording tape pattern. (B) is an explanatory view showing a cylinder rotation deviation at the time of recording. In FIG. 2, for example, the recording tape pattern by phase control when the limiter level is set to X at the time of recording and the VSYNC phase of the recording signal is deviated is shown in FIG.
It is recorded as shown in (a). Therefore, in this case, since the limiter level is set to X, the value synthesized from the phase detection system becomes small. As a result, FIG. 2 (b)
As shown in, the rotation deviation of the cylinder can be reduced. As a result, it is possible to prevent a screen flow and color disorder at the time of reproduction, which are problems in the past.

However, in this case, there is a problem that it takes time to pull in the phase as shown in FIG. 4B, but in the present embodiment, in the modes other than recording,
By setting the limiter level to Y, that is, by increasing the limiter level and speeding up the pull-in, this problem can be solved and the time from the reproduction image output or the recording standby to the recording start can be shortened.

[0042]

Since the phase pull-in is slow during recording, even if the recording signal is discontinuous, no screen flow or color disorder occurs during reproduction. In addition, since the phase pull-in is quick except during recording, it is possible to shorten the time from displaying the image for reproduction to starting recording.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a phase control device according to the present invention.

FIG. 2 is an explanatory diagram showing recording tape patterns and frequency deviations when phase pull-in is slow.

FIG. 3 is a block diagram showing a conventional phase control device.

FIG. 4 is an explanatory diagram showing a recording pattern and a frequency deviation when the phase pull-in is early.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylinder motor 2 ... Pulse generator 3 ... Frequency generator 4, 5 ... Schmitt circuit 6 ... VSYNC oscillator 7 ... Phase detector 8 ... Speed detector 9a ... 1st limiter 9b ... 2nd limiter 10 ... Synthesis Means 11 ... Filter 12 ... Amplifier 13 ... Driver circuit 14 ... Switching signal transmitting means

Claims (2)

[Claims] 1. A first signal detecting means for obtaining a speed signal corresponding to a rotation speed of a cylinder motor, a second signal detecting means for obtaining a phase signal corresponding to a rotation phase of the cylinder motor, and the speed signal. Speed detection means for detecting a speed difference signal between the target rotation speed of the cylinder motor, phase detection means for detecting a phase difference signal between the phase signal and the target rotation phase of the cylinder motor, and from the phase detection means Switching means for switching the phase difference signal according to each mode by a control signal, and first and second limiting means for limiting the phase difference signal switched by the switching means to the phase difference signal corresponding to each mode. A limiter; combining means for combining the phase difference signal from the first or second limiter and the speed difference signal; A phase control device comprising: means for driving the cylinder motor by applying a DC voltage having a predetermined value according to the combined output. 2. The limit value of the first limiter is set to the second limit value.
2. The phase control according to claim 1, wherein the limiter is set to be smaller than the limiter limit value, and the first limiter is selected during recording by the switching means, and the second limiter is selected in other modes. apparatus.