JPH0664799B2 - Tape traveling control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape running controller, and more particularly to a tape running controller for controlling tape running by a control pulse recorded in advance on a tape.

(Prior Art) Ordinary Video Tape Recorder (hereinafter referred to as VTR)
At the time of recording, the video signal is recorded on an inclined video signal track on the magnetic tape, and at the same time, a control pulse (hereinafter referred to as a CTL pulse) is applied to the control signal track in the longitudinal direction of the magnetic tape. Saturated magnetic recording is performed for each pulse in synchronization with the frame.

Next, when reproducing the video signal recorded on the tape as described above, the CTL pulse is read by the CTL head in order to stably reproduce the video signal. The traveling speed is controlled.

Therefore, as the CTL pulse output, a pulse synchronized with the frame can be obtained, and the CTL pulse frame counter is configured by counting (incrementing counting or decrementing counting) this pulse in combination with the information of the tape running direction. It is.

(Problems to be Solved by the Invention) By the way, in the above-mentioned CTL pulse frame counter, its accuracy depends on whether or not the CTL pulse is surely output in synchronization with the frame.

On the other hand, the CTL pulse is saturated magnetically recorded as described above, and the reproduction CTL pulse output is obtained only when the tape is running. Then, the direction of this output current is repeated once every frame. Also, the direction of the output current is naturally opposite when the tape running direction is reversed.

However, there are the following two problems when using the CTL pulse having such characteristics (that is, the CTL head output signal) in the above-mentioned CTL pulse frame counter.

The pulse edge of the CTL pulse on the tape (where the signal is inverted) when the tape running is stopped
When the CTL head is located at, the next time the tape travel is started, an unnecessary (illegal) pulse may be generated for a moment.

When the tape running is stopped and then the tape is running in the opposite direction to the previous one, an unnecessary (illegal) pulse may be generated for a moment.

Therefore, the present invention solves the above-mentioned problems of the conventional technique and prevents the generation of unnecessary (illegal) pulses in the above two cases, thereby configuring a highly accurate frame counter, and It is an object of the present invention to provide a tape running control device capable of accurately controlling tape running.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention is a tape running control device for controlling tape running by detecting a control pulse previously recorded on a tape by a control head. When stopping or reversing the tape running,
The tape traveling speed decelerating means for decelerating the tape traveling speed to a sufficiently small value within the range where the control pulse on the tape is detected by the control head, and the control head from the tape decelerated by the tape traveling speed decelerating means. Measuring means for measuring the time from the pulse edge of the detected control pulse, and when the measuring means measures a predetermined time, the tape running is braked and the tape running stop position is controlled by the control pulse with respect to the position of the control head. The tape running stop means that stops the tape so that the position of is always at the position avoiding the pulse edge of the control pulse is provided, and unnecessary control pulses are not detected when the tape running is restarted. To provide a tape running control device A.

(Operation) In the tape running control device having the above-described configuration, when the tape running speed is high, the influence of mechanical factors of braking (such as friction with the tape) cannot be ignored, and the tape stops running from the beginning of braking. There may be a case where it is difficult to stop the tape at a predetermined position (a position within the range where the above influence does not occur) due to a large variation in the tape traveling distance up to

Therefore, when stopping the tape running, first, the tape running speed is controlled so as to drop to a sufficiently small value within a range in which the CTL pulse on the tape is detected by the CTL head and the output thereof is obtained. The following tape running control needs to be performed.

Next, when the CTL head detects the pulse edge of the CTL pulse from the tape whose tape traveling speed has decreased as described above, the measuring means starts the time measurement from this moment (the timer starts operating).

Then, as shown in FIG. 2, the preset time t ₁
After the passage of time, the tape running stopping means starts braking the tape running. The tape running is stopped after a certain time t ₂ .

As a result, the stop position of the tape is set to the tape running speed V ₀ before the start of the braking control with respect to the edge detection position of the CTL pulse (duty is 1: 1), that is, the recording position of the CTL pulse, and is determined from the speed. Let S ₀ ± S _e (however, S _{e be} an error) be the tape travel distance from when braking starts to when tape travel stops.
It will stop after a distance of V ₀ × t ₁ + S ₀ ± S _e .

Note that this S ₀ ± S _e is a unique value depending on the combination of the tape running device such as a VTR and the tape used.

Therefore, by setting the time t ₁ and the tape running speed V ₀ to appropriate values, the recording position of the CTL pulse on the tape is always described above with respect to the CTL head position.
Can be set to a position S where the above problem does not occur (that is, a position where the pulse edge of the CTL pulse is avoided).

This prevents an unnecessary signal (CTL pulse) from being output the next time the tape is run.

(Example) An example of the tape running control device according to the present invention will be described.
A description will be given below with reference to the drawings.

FIG. 1 is a block system diagram showing an embodiment of a tape running control device according to the present invention. In this block diagram, only a part of the running control system of the video tape is shown,
The video signal system is omitted. FIG. 3 is an operation flowchart of the device of the present invention shown in FIG.

In the figure, 1 is a CTL head and 2 is a CTL head 1.
It is a pulse counter (frame counter) that counts output pulses from.

Reference numeral 3 is a timer (timer counter) triggered (starting counting) by the pulse edge of the CTL pulse, which constitutes a measuring means.

Reference numeral 4 denotes a microcomputer that controls a timer (timer counter) 3 and a motor drive circuit 6 that drives a capstan motor (M) 7 by inputting a pause command.

5 is a pause switch for giving a pause command, 6 is a motor drive circuit for driving the capstan motor (M) 7,
7 is a capstan motor (M).

Reference numeral 8 is a pulse generator that generates a count pulse as a reference of the timer (timer counter) 3.

The microcomputer 4, the pause switch 5, and the motor drive circuit 6 are used when the timer (timer counter) 3 measures a predetermined time {that is, the timer (timer counter) 3
When a predetermined value is counted}, the capstan motor (M) 7 is braked to form a tape running stopping means for stopping the tape running.

In the above configuration, when the VTR is reproducing the video signal recorded on the video tape, the CTL
A signal (CTL pulse) read by the head 1 is supplied to a pulse counter (frame counter) 2. Then, the pulse counter 2 increments (or decrements) the counter value by one each time a CTL pulse is supplied together with the tape traveling direction (rewind / fast-forward) information supplied from the outside.

Further, in the operation flowchart of FIG. 3 (processing flowchart of the microcomputer 4), when the pause switch 5 is pressed down and the pause command is given to the VTR, the microcomputer 4 is supplied from the CTL head 1. When the current tape running speed based on the CTL pulse is higher than the specified value, the motor drive circuit 6 is instructed to reduce the tape running speed (speed down command).

In addition, the above specified value is that the CTL pulse on the tape is CT
The value read by the L head 1 is set to a sufficiently small value.

When the tape running speed reaches a predetermined speed (specified value), a timer (timer counter) 3 is set to a predetermined value (data).

Further, the timer (timer counter) 3 is activated by the CTL pulse (pulse edge detection) supplied from the CTL head 1 to the microcomputer 4 immediately after the setting.
The count (countdown) is started. And
The timer (timer counter) 3 is sequentially operated by the CTL head 1.
It is counted (counted down) by the CTL pulse supplied from.

Furthermore, when the timer (timer counter) 3 becomes "0",
A braking command is issued from the timer (timer counter) 3 to the motor drive circuit 6, and this motor drive circuit 6 stops the capstan motor (M) 7, which stops the tape running.

At this time, the tape is stopped so that the position of the CTL head 1 is at a position avoiding the pulse edge of the CTL pulse, which is separated from the edge position of the CTL pulse by a certain distance. Since no unnecessary pulse is generated at the start, the pulse counter (frame counter) 2 does not count incorrectly.

As described above, the pulse counter (frame counter) 2 with high accuracy can be configured by preventing the generation of unnecessary CTL pulses.

(Advantages of the Invention) As described above, according to the tape running control device of the present invention, the tape running stop position is located at a position where the control pulse position is always avoiding the pulse edge of the control pulse with respect to the position of the control head. When the tape is stopped and the tape starts to run next time, unnecessary control pulses can be prevented from occurring, so that the control head is always in contact with the tape during operation. VTR),
A highly accurate control pulse frame counter can be configured and highly accurate relative position information of the tape can be obtained, so that the tape running can be controlled with high accuracy. In particular, the control pulse on the tape detects the tape running speed by the control head. The tape running is controlled after decelerating to a sufficiently small value within the range
It has the feature that the tape running can be controlled more accurately in electronic editing such as, and cueing.

[Brief description of drawings]

FIG. 1 is a block system diagram showing an embodiment of a tape running control device according to the present invention, FIG. 2 is a diagram for explaining the operation of the present invention device, and FIG. 3 is the present invention device of FIG. It is an operation | movement flowchart. 1 ... CTL head, 2 ... Pulse counter (frame counter), 3 ... Timer (timer counter), 4 ... Microcomputer, 5 ... Pause switch, 6 ... Motor drive circuit, 7 ... Capstan motor (M), 8 ... Pulse Generator.

Claims (1)

[Claims] 1. A tape running control device for controlling tape running by detecting a control pulse previously recorded on a tape with a control head, wherein the tape running speed is set when stopping or reversing the tape running. Tape traveling speed decelerating means for decelerating the control pulse on the tape to a sufficiently small value within the range detected by the control head, and a control pulse detected by the control head from the tape decelerated by the tape traveling speed decelerating means. Measuring means for measuring the time from the pulse edge of the tape, and when the measuring means measures a predetermined time, the tape running is braked so that the tape running stop position is always relative to the position of the control head. At a position avoiding the pulse edge of the control pulse When starting again the tape running is provided a tape transport stop means for stopping so that the tape, the tape running control apparatus characterized by unwanted control pulse is prevented from being detected.