JPH0689486A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To realize a stable and speedy transient performance with few overshooting in the transient state of a phase control system only by equivalently increasing the sample rate of a capstan phase system by a signal. CONSTITUTION:A speed control output of a speed control block 6 and a speed control output delayed in the amount of one cycle of CFG by a delay circuit 12 are integrated, and to this integrated output, a tracking control output of a tracking control block 9 is added. On this addition of the integrated output and tracking control output, the integrated output is initialized to a prescribed value by an integrated value control block 11 based on a tracking control timing signal which is outputted from the tracking control block 9 for every time the tracking control is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a capstan motor speed control circuit for running a magnetic tape at a constant speed and a capstan motor phase control circuit for performing phase control based on tracking information on the magnetic tape. The present invention relates to a magnetic recording / reproducing device.

[0002]

2. Description of the Related Art In recent years, video tape recorders (hereinafter referred to as
Abbreviated as VTR. ) Is highly required, and the improvement of the transient response of the capstan motor is one of the performance improvements that is strongly desired for realizing a quick mode transition of the VTR. The most basic method of improving the transient response is to increase the sample rate of the capstan phase control system to widen the phase control band, for example, Japanese Patent Laid-Open No. 64-3.
According to Japanese Patent Laid-Open No. 845, when a control signal (hereinafter abbreviated as CTL signal), which is a tracking control signal at the time of reproduction, is recorded on a magnetic tape, a high frequency pilot signal is also superposed and recorded, and the reproduction frequency of the pilot signal A method has been proposed in which the sample rate of a capstan phase control system is increased by performing capstan phase control so that the sample rate becomes constant.

[0003]

In the case of the VHS system, the sample rate in the conventional capstan phase control system during reproduction is C, which is the capstan phase control signal during reproduction.
Since the recording cycle of the TL signal is defined by the standard to be the same as the vertical synchronizing signal of each television system, the frequency of the vertical synchronizing signal is the limit. Therefore, the sample rate cannot be simply increased to improve the transient response, and the method disclosed in Japanese Patent Laid-Open No. 64-3845 has been proposed. However, in this method, when the self-reproduced reproduction, that is, the reproduction of the magnetic tape on which the high frequency pilot signal is not superposed and recorded, the high frequency pilot signal is not detected, so that the sample rate cannot be increased. Further, in this capstan phase control method, a special high-frequency pilot signal which is not in the standard is used for phase control, and thus a special circuit configuration is required.

[0004]

A magnetic recording / reproducing apparatus according to the present invention comprises means for accumulating and holding speed control outputs in a capstan system, and a phase based on the integration result and tracking information recorded on a magnetic tape. By configuring so that the result of adding the control outputs becomes the final capstan phase control output, the sample hold period of the tracking control output is interpolated, and only the control signal that has been used in the past is used. The sample rate of the stun phase control system is equivalently increased.

[0005]

According to the present invention, since the sample hold period of the tracking control output can be interpolated by using only the control signal which has been conventionally used, the effect of equivalently increasing the sample rate of the capstan phase control system can be obtained. In a so-called transient state until the target frequency of the capstan motor changes and the output of the phase system falls, the capstan phase control system can have stable and quick transient characteristics with little overshoot.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the capstan motor control according to the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, the control of a capstan motor can be roughly divided into a speed control block and a phase control block. First, the capstan speed control system will be described.

In FIG. 1, the magnetic tape 1 is transferred by a capstan shaft 3 which rotates according to the rotation speed of a capstan motor 2. The capstan motor 2 is provided with a frequency generator for obtaining speed control information, and the output of the frequency generator (hereinafter abbreviated as CFG).
Is detected by the frequency detector 4 and supplied to the amplifier 5. The amplifier 5 amplifies the supplied CFG into a pulse signal as shown in FIG. 2A and supplies it to the speed control block 6. The speed control block 6 measures the cycle of the CFG, performs a comparison calculation with the target cycle to calculate the speed control output, and controls the capstan motor to rotate at the target speed. After the speed control output is multiplied by Kp by the amplifier 7,
It is added to the phase control output and supplied to the motor drive circuit 16 via the phase compensation filter 15. The motor drive circuit 16 drives the capstan motor.

Next, the capstan phase control system during reproduction will be described. In FIG. 1, the tracking information recorded on the magnetic tape 1 is detected by the tracking signal detection block 8 and supplied to the tracking control block 9. Here, the tracking signal detection block 8
In the case of the VHS system, the tracking information detected at is the CTL signal recorded on the control track on the magnetic tape 1. The tracking control block 9 outputs the tracking control output to the amplifier 10 so that the phase of the input CTL signal and the predetermined reference signal becomes constant, and at the same time, the tracking control timing signal as shown in FIG. Output to the control block 11. The integrating operation of the speed control output, which is a characteristic function of the present invention, is realized by adding the output of the speed control block 6 and the speed control output delayed by one cycle of the CFG by the delay circuit 12, and the integrating operation is performed. The output is multiplied by K by the amplifier 13 and then output to the integrated value control block 11.
The integrated value control block 11 initializes the integrated output to a predetermined fixed value at the tracking control timing shown in FIG. 2B, and outputs the integrated output multiplied by the above K only during the sample hold period of the tracking control output. . The output of the integrated value control block 11 is added to the tracking control output multiplied by Ki by the amplifier 10 to obtain the final phase control output. This final phase control output is shown in FIG.
As shown in (c), the tracking control output has a waveform obtained by interpolating as shown by the shaded portion in the sample hold period, and this is added to the above-mentioned speed control output via the phase compensation filter 14. The block 17 shown by the broken line in FIG. 1 is a calculation processing block in the capstan motor speed control and phase control of this embodiment, and this can be realized by either software or hardware.

In this embodiment, the speed control output integration processing is performed in the CFG cycle. However, the integration processing is performed by the CFG.
Even if the cycle is divided by N, if the cycle is shorter than the tracking control system sample hold cycle, it can be easily inferred that the same result is obtained. In addition, the initial value of the integrated output in the present embodiment is not limited to a fixed value, and the same effect can be obtained by variably controlling based on the offset amount between the integrated value of the speed control output and the tracking control output. You can In the following, the speed control output integration process is
FIG. 3 shows a case in which the FG is divided by N and a case in which the integrated output and its initial value are variably controlled based on the offset amount between the integrated value of the speed control output and the tracking control output.
Will be described with reference to the block diagram of FIG. Note that the description of the blocks in FIG. 3 that overlap with FIG. 1 is omitted.

In the block diagram for explaining another embodiment as shown in FIG. 3, the speed control block 6 is a CFG.
Of the FV conversion block 18 and CF for calculating the speed control output by measuring the cycle of
It can be divided into G division blocks 19. CFG above
The frequency dividing block 19 has a configuration in which an arbitrary frequency dividing number can be set, and C which is obtained by dividing the input CFG into a predetermined cycle.
The FG frequency divider circuit output is output to the switch circuit 20. The output of this CFG divider circuit turns on / off the switch circuit 20.
Since the speed control output is turned off and the speed control output to be output to the delay circuit 12 is thinned out, the integration processing of the speed control output is performed in the N division cycle of the CFG. The offset detection block 21 calculates and holds the tracking offset amount based on the input integrated value of the speed control output and the tracking control output, and outputs it to the integrated value control block 11. The integrated value control block 11 variably controls the integrated output and its initial value based on the input tracking offset amount. As a result, the above tracking offset is corrected.

Although the present embodiment has been described with respect to the VHS system, the present invention can be applied to an 8 mm system VTR having a sample hold circuit with a low sample rate in the tracking control system. In this case, It is presumed that the same result can be obtained by replacing the tracking information input to the tracking signal detection block 8 in FIG. 1 with the video signal and the four-frequency pilot signal recorded in a superimposed manner.

[0012]

By performing the capstan control as described above, even if the tracking control output largely changes in the transient state of the capstan motor, the speed control output integration loop quickly interpolates the tracking control output. Therefore, the capstan phase control system can obtain good transient characteristics with less overshoot. Therefore,
According to the present invention, quick mode transition of the capstan motor can be realized.

[Brief description of drawings]

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

FIG. 2 is a waveform diagram of each part for explaining the capstan motor phase control system of the present invention.

FIG. 3 is a block diagram showing another embodiment of the present invention.

[Explanation of symbols]

 1 ... Magnetic tape, 2 ... Capstan motor, 3 ... Capstan shaft, 4 ... Frequency detector, 5 ... Amplifier, 6 ... Speed control block, 7 ... Amplifier, 8 ... Tracking signal detection block, 9 ... Tracking control block, 10 ... Amplifier, 11 ... Integrated value control block, 12 ... Delay circuit, 13 ... Amplifier, 14 ... Phase compensation filter, 15 ... Phase compensation filter, 16 ... Motor drive circuit, 17 ... Arithmetic processing block, 18 ... FV conversion Blocks, 19 ... CFG frequency dividing block, 20 ... Switch circuit, 21 ... Offset detection block, a ... CFG, b ... Tracking control timing signal, c ... Final capstan phase control output.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Nakamoto 1410 Inada, Katsuta, Ibaraki Hitachi, Ltd. AV equipment division (72) Inventor Yoshio Narita 1410 Inada, Katsuta, Ibaraki Hitachi, Ltd. Studio AV Equipment Division

Claims (4)

[Claims] 1. A speed control circuit for keeping the rotational speed of a capstan motor for running a magnetic tape at a target frequency based on the output of a frequency generator, and tracking information recorded on the magnetic tape during reproduction. A magnetic recording / reproducing apparatus comprising a phase control circuit for detecting and detecting the phase of the capstan motor based on the tracking information, and a means for accumulating and holding the output of the speed control circuit is provided. A magnetic recording / reproducing apparatus characterized in that the phase control of a capstan motor is performed by the addition result of the output of the phase control circuit based on the tracking information recorded on the tape. 2. The magnetic recording and reproducing apparatus according to claim 1, further comprising means for dividing the output of the frequency generator, and based on the divided output, the integration cycle of the output of the speed control circuit is set. Magnetic recording / reproducing device characterized by the above. 3. In the addition of the integrated value of the speed control circuit output according to claim 2 and the output of the phase control circuit based on the tracking information, when the phase control circuit output based on the tracking information is updated, the integrated value of the speed control circuit output is set to a predetermined value. A magnetic recording / reproducing apparatus characterized by performing the above-mentioned phase control by initializing to a value of. 4. The magnetic recording / reproducing apparatus according to claim 3, further comprising means for detecting an offset amount between the tracking control output and the integrated value of the speed control output, and the integrated value of the speed control output based on the offset amount. A magnetic recording / reproducing apparatus characterized by setting an initial value of.