JPS6258446A - Reproducing device - Google Patents

Abstract

PURPOSE:To simplify a circuit and to narrow the substrate area and to reduce the cost by providing a changeover switch which switches and supplies a control pulse reproduced from a magnetic tape and a step pulse to a tape position counter. CONSTITUTION:The object is a reproducing device where slow reproducing is possible and a capstan motor is controlled by a step pulse Ps for slow reproducing. A changeover switch 21 which switches and supplies a control pulse CTL reproduced from the magnetic tape and the step pulse Ps to a tape position counter 23 is provided, and the step pulse Ps is supplied to the tape position counter 23 for slow reproducing, and the control pulse CTL is supplied there for reproducing other than slow reproducing. Since the step pulse Ps is supplied to the tape position counter 23 instead of the control pulse CTL for slow reproducing, the tape position counter 23 does not miscount even if the control pulse CTL is dropped out for slow reproducing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a playback device that is capable of slow playback and that controls a capstan motor using step pulses during slow playback.

[Summary of the invention]

The present invention provides a playback device in which a capstan motor is controlled by step pulses during slow playback, and the step pulses are supplied to a tape position counter during slow playback, so that magnetic tape can be played back. This is designed to prevent the tape position counter from counting erroneously due to missing control pulses.

[Conventional technology]

Figure 4 shows an example of an editing system (11 is a helical scan type playback VTR (video tape recorder'), (2) is a playback VTR+11 that supplies video signals Sv and audio signals S^. A helical scan type recording VTR (31 is a controller for controlling the reproduction VTR (1) and the recording VTR (2). The control pulse CTLA reproduced from the control track formed in the longitudinal direction of the tape is transmitted to the controller (3).
) is supplied as a clock pulse to the tape position counter (4). One control pulse CTL^ is reproduced in each frame. Then, the tape position is displayed on the counter (4), for example, 0 hours, 00 minutes, 0 seconds, 00 frames.

Further, in the recording VTR (2), a control pulse CT Ls reproduced from the control track during pre-rolling, for example, is supplied as a clock pulse to the tape position counter (5) of the controller (3).
Tape position 1 is displayed on this counter (5).

In addition, from the controller (3) to V T Ril) and (2
) are supplied with control signals SCA and SCs, respectively, to control their respective operations.

As shown in the example in Figure 4, with a system that counts control pulses to know the tape position and control the editing point, for example, during slow playback, the tape speed decreases and control pulses are dropped. , there was a problem that caused miscounts.

Conventionally, in order to compensate for the lack of control pulses during slow playback, it is known to divide the pulse from the frequency generator of the capsun block and replace it with the control pulse during slow playback. FIG. 5 shows an example.

In the figure, (6) is a control pulse detection block, and the control pulse CTL obtained from this block is
is supplied to the fixed terminal on the B side of the changeover switch (7).゛Also, (8) is a capsun block, and the pulse PF from the frequency generator (FC) obtained from this is
G is supplied to fixed terminals on the A side, B side, and C side of the changeover switch αψ via frequency dividing circuits (9a), (9b), and (9c). In this case, the number of pulses PFGO for one frame is such that the tape running speed at the time of recording is 1. Second
and a third time, for example βI.

It differs in β■ and β■ modes. Therefore, the frequency dividing circuits (9a), (9b) and (9c) are configured so that the tape running speed during recording is the first. At the second and third times, the frequency is divided to obtain one pulse for each frame. In addition, the changeover switch is set to the controller (1
The speed designation signal S1 from 1) causes the tape running speed during recording to be set to 1. At the second and third times, A side, B (
Switched to IIJ and C sides.

Therefore, one pulse is obtained for each frame at the movable terminal of the changeover switch [alpha], similar to the control pulse CTL.

The output of this changeover switch αψ is the A of changeover switch (7).
Supplied to the side terminal. The output of this changeover switch (7) is supplied to a tape position counter (12).

In this case, the changeover switch (7) is
) is used to switch to the A side during slow playback, and to the B side during other playbacks. Therefore, the tape position counter (12) is supplied with a signal obtained by frequency-dividing the pulse ppa during slow playback, and is supplied with a control pulse CTL during other playbacks.

After all, according to the example in FIG. 5, even if the control pulse CLT is missing during slow playback, the frequency-divided signal is supplied to the tape position counter (12), so there is no need to worry about miscounting. .

[Problem that the invention seeks to solve]

However, in the example in FIG. 5, the frequency dividing circuits (9a) to (9c)
However, since the circuit is complicated and the number of ICs is large, it is disadvantageous in terms of board area and cost.

In view of these points, the present invention aims to simplify the circuit, reduce the board area, and reduce the cost.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention is directed to a playback device that is capable of slow playback and that controls the capstan motor using step pulses Ps during slow playback. Then, a changeover switch (
21) is provided, and a step pulse Ps is supplied to the tape position counter (23) during slow playback, and a control pulse CTL is supplied during other playbacks.

[Effect]

During slow playback, the step pulse Ps is supplied to the tape position counter (23) instead of the control pulse CTLO.
Even if L is missing, the tape position counter (23) will not miscount.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIG.

In this example, during slow playback (slow running), the rotation control of the capstan motor is performed by the system controller (20
), and when one step pulse Ps is output, the capstan is activated by one control pulse CTL (one frame).
is rotated only.

That is, one screen is sent with one step pulse Ps.

In FIG. 1, a step pulse Ps from a system controller (20) is supplied to a fixed terminal on the A side of a changeover switch (21). Further, the control pulse CTL from the control pulse detection block (22) is supplied to the fixed terminal on the B side of the changeover switch (21). The output of this changeover switch (21) is supplied to a tape position counter (23).

The changeover switch (21) is set to the A side during slow playback by the slow control signal S3 from the controller (20).
During other reproductions, it is switched to the B side. therefore,
A step pulse Ps is supplied to the tape position counter (23) during slow reproduction, and a control pulse CTL is supplied during other reproductions.

As described above, in this example, during slow playback (during slow running), the step pulse Ps is supplied to the tape position counter (23) instead of the control pulse CTLO, so that the control pulse CTL may be missing during slow playback. Even if the tape position counter (23) is used, the tape position counter (23) will not miscount.

In this way, according to this example, compared to the conventional circuit that divides the frequency of the pulse PFG from the frequency generator, there is no need for a frequency divider circuit, so the circuit is simpler, the board area is significantly reduced, and it is also less expensive. There are profits that can be made up of.

FIG. 2 shows a specific configuration example, and parts corresponding to those in FIG. 1 are denoted by the same reference numerals.

In the figure, (22a) is a magnetic head that reproduces a control pulse CTL from a control track of a magnetic tape, and the control pulse CTL reproduced by this magnetic head (22a) is transmitted via an amplifier (22b) to a changeover switch ( 21) is supplied to the B side fixed terminal.

Further, the step pulse Ps from the system controller (20) is transmitted to the differential circuit (24a) and the waveform shaping circuit (24).
b) The pulse width correction circuit (24) makes the pulse width substantially the same as the pulse width of the control pulse CTL, and then the pulse width is supplied to the fixed terminal on the A side of the changeover switch (21).

Further, the slow control signal S3 from the system controller (2o) is transmitted to the integrating circuit (25a) and the waveform shaping circuit (25).
b) After being delayed for a predetermined time by the delay circuit (25), the signal is supplied to the changeover switch (21) as a changeover control signal. In this case, when the switching control signal is at a low level "θ", it is connected to the B side, and when it is at a high level "1", it is connected to the A side.

In the example in FIG. 2, when the pause button is pressed at time t to perform slow playback (frame-by-frame playback) using the shuttle dial (not shown), the system controller The slow control signal S3 from 20) changes from a low level "0" to a high level "1" at this time t1. The signal supplied to the changeover switch (21) changes from the low level 10'' to the high level ``1'' at time t2 after a predetermined time delay, as shown in FIG. 3E. The delay time of the circuit (25) is the time until the capstan is completely in the pause state.The signal supplied to the changeover switch (21) changes from low level "0" to high level "1" at time t2. ”, the changeover switch (21) switches from the B side to the A side at this time t2.
The state in which the control pulse CTL is supplied to the tape position counter (23) is changed to the state in which the step pulse Ps is supplied to the tape position counter (23).

In the above state, when the user operates the shuttle dial, the system controller (20) outputs the step pulse Ps as shown in FIG. 3B, and the correction circuit (24) outputs the step pulse Ps as shown in FIG. After the pulse width is corrected as shown in , it is supplied to the tape position counter (23) via the fixed terminal on the A side of the changeover switch (21).

Furthermore, when the slow playback by operating the shuttle dial is finished and the pause state is released at time L3, the slow control signal S3 from the system controller (20) is at a high level at time t3, as shown in the third diagram. 1” to a low level “0”. Further, the delay circuit (25) delays only the rising edge, and the changeover switch (21)
) is also applied at time t, as shown in Figure 3.
3, the high level goes from "1" to the low level "0". Therefore, the changeover switch (21) is switched from the A side to the B side at this time t3, and the control pulse CTL is returned to the state where it is supplied to the tape position counter (23).

The example in Fig. 2 operates as described above, and Fig. 3A shows the control pulse CTL reproduced by the magnetic head (22a).
Even if there is a dropout (as shown by the dashed line), during this slow playback,
Instead of control pulse CTL, step pulse (
3C) is supplied to the tape position counter (23), so that no miscount occurs in the tape position counter (23). Figure 3F shows the tape position counter (2
3) shows the pulses supplied.

In addition, the control pulse CTL and the step pulse (third
The phase shift shown in Figure C) is not a particular problem, i.e.
Since this pulse is simply a counter pulse, if there is one pulse in one frame, the phase shift will not be a particular problem.

〔Effect of the invention〕

According to the present invention described above, during slow playback, step pulses are supplied to the tape position counter to prevent counting errors due to missing control pulses, and pulses from the frequency generator are not used as in the conventional method. Compared to the case where the frequency is divided, there is no need for a frequency dividing circuit, so the circuit becomes simpler, the board area is significantly reduced, and it can be constructed at a lower cost.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a specific configuration diagram thereof, and FIG. 3 is a diagram for explaining the operation of the example in FIG.
FIG. 4 is a diagram showing an example of an editing system, and FIG. 5 is a configuration diagram of a conventional example. (20) is the system controller, (21) is the changeover switch, (22) is the control pulse detection block, (
23) is a tape position counter. Figure 1 Figure 4 Figure 5

Claims (1)

[Claims] In a playback device that is capable of slow playback and controls a capstan motor using step pulses during slow playback, a control pulse played from a magnetic tape and the step pulse are used as a tape position counter. A reproducing apparatus characterized in that a changeover switch is provided to supply the step pulse to the tape position counter during slow reproduction, and the control pulse is supplied to the tape position counter during other reproductions.