JPH0656709B2 - Playback device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a reproducing device capable of slow reproduction and adapted to control a capstan motor by a step pulse during slow reproduction.

[Outline of Invention]

According to the present invention, in the reproducing apparatus adapted to control the capstan motor by the step pulse during the slow reproduction, the step pulse is supplied to the tape position counter during the slow reproduction, so that the reproduction is performed from the magnetic tape. This is intended to prevent the count error of the tape position counter due to the lack of the control pulse.

[Conventional technology]

FIG. 4 shows an example of an editing system. (1) is a helical scan type reproduction VTR (video tape recorder), and (2) is a reproduction VTR (1) from the video signal S _V and the audio signal S _A. Helical scan type recording VT supplied with
R and (3) are controllers for controlling the reproducing VTR (1) and the recording VTR (2). In the reproducing VTR (1), the control pulse CTL _A reproduced from the control track formed in the longitudinal direction of the magnetic tape is supplied to the tape position counter (4) of the controller (3) as a clock pulse. This control pulse CTL
_{One A} is reproduced in each frame. And the counter
In (4), the tape position is displayed, for example, XX hours XX minutes XX seconds XX frames.

Further, in the recording VTR (2), for example, the control pulse CTL _B reproduced from the control track during preroll is the tape position counter of the controller (3).
This counter (5) is supplied as a clock pulse to (5).
The tape position is displayed on. The control signals SC _A and SC _B are supplied from the controller (3) to the VTRs (1) and (2), respectively, and their operations are controlled.

According to the method of counting the control pulse to know the tape position and performing the edit point control as in the example of FIG. 4, the tape speed becomes small and the control pulse is lost during slow reproduction, for example. , There was a problem that caused a miscount.

Therefore, conventionally, in order to compensate for the loss of the control pulse during slow reproduction, it is known to divide the pulse from the frequency generator of the capstan block and replace it with the control pulse during slow reproduction. FIG. 5 shows an example thereof.

In the figure, (6) is a control pulse detection block, and a control pulse CTL obtained from this block.
Is supplied to the B-side fixed terminal of the changeover switch (7).

Further, (8) is a capstan block, and the pulse P _FG from the frequency generator (FG) obtained from this is passed through the frequency dividing circuits (9a), (9b) and (9c), and the changeover switch (1
It is supplied to the fixed terminals of A side, B side and C side of 0). In this case, the number of pulses P _FG for one frame is, for example, β when the tape traveling speed during recording is the first, second and third.
Different in I, βII and βIII modes. Therefore, the frequency dividing circuits (9a), (9b), and (9c) obtain one pulse for each frame when the tape running speed during recording is the first, second, and third. It is divided into.
Further, the changeover switch (10) receives the speed designation signal S ₁ from the controller (11) when the tape running speeds at the time of recording are the first, second and third sides, respectively, the A side, the B side and the C side. Is switched to. Therefore, one pulse is obtained for each frame at the movable terminal of the change-over switch (10) similarly to the control pulse CTL.

The output of the changeover switch (10) is supplied to the A side terminal of the changeover switch (7). The output of the changeover switch (7) is supplied to the tape position counter (12). In this case, the changeover switch (7) is switched to the A side during slow reproduction by the slow control signal S ₂ from the controller (11) and to the B side during other reproduction. Therefore, the tape position counter (12) is supplied with a signal obtained by _{dividing the} pulse P _FG during slow reproduction, and the control pulse CTL during other reproduction.

After all, according to the example of FIG. 5, even if the control pulse CLT is lost during slow reproduction, since the frequency division signal is supplied to the tape position counter (12), there is no fear of miscounting.

[Problems to be solved by the invention]

However, the example of FIG. 5 has frequency divider circuits (9a) to (9c), which is complicated in terms of circuit and has a large number of ICs, which is disadvantageous in terms of substrate area and price.

In view of the above points, the present invention aims to simplify the circuit, reduce the substrate area, and reduce the price.

[Means for solving problems]

The present invention for solving the above problems, can slow reproduction, the slow reproduction is to target playback device has been made to control the capstan motor to perform at step pulse P _S. Then, the control pulse CTL and step pulse P _S to be reproduced from the magnetic tape is provided the switch (21) for switching and supplying the tape position counter (23), the tape position counter (23), slow reproduction step pulse supplying P _S, when other reproduction and supplies the control pulse CTL.

[Action]

The tape position counter (23), slow reproduction, instead of the control pulse CTL, since supplying step pulse P _S, slow reproduction, even missing control pulses CTL, the tape position counter (23) is mis It doesn't count.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In this example, during slow reproduction (during slow running), the rotation control of the capstan motor is performed by the step pulse P _S output from the system controller (20).
When pieces of step pulse P _S is output, the capstan is rotated by one control pulse CTL (one frame). That is, one screen is sent by one step pulse P _S.

In FIG. 1, step pulse P _S from the system controller (20) is supplied to the fixed terminal on the A side of the changeover switch (21). In addition, the control pulse detection block (2
The control pulse CTL from 2) is the changeover switch (21).
Is supplied to the fixed terminal on the B side. The output of the changeover switch (21) is supplied to the tape position counter (23).

The change-over switch (21) is switched to the A side during slow reproduction and to the B side during other reproductions by the slow control signal S ₃ from the controller (20). Thus, the tape position counter (23), the step pulse P _S is the slow reproduction is the other control pulse CTL during playback
Is supplied.

In this way, in the present embodiment, slow reproduction (during slow running), the tape position counter (23), instead of the control pulse CTL, since step pulse P _S is supplied, slow reproduction, control pulse CTL If the tape is missing, the tape position counter (23) will not miscount.

As described above, according to this example, as compared with the conventional circuit that _divides the pulse P _FG from the frequency generator and uses it, the frequency dividing circuit is unnecessary, so the circuit is simple and the substrate area is significantly reduced, and There is a benefit of being cheaply constructed.

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

In the figure, (22a) is a magnetic head for reproducing a control pulse CTL from a control track of a magnetic tape, and the control pulse CTL reproduced by this magnetic head (22a) is switched by an amplifier (22b).
It is supplied to the fixed terminal on the B side of (21).

Further, the system controller step pulse P _S is a differential circuit from (20) (24a) and the waveform shaping circuit a pulse width correction circuit consisting of (24b) (24), substantially the same as the pulse width of the pulse width control pulse CTL Then, it is supplied to the fixed terminal on the A side of the changeover switch (21).

The slow control signal S ₃ from the system controller (20) is delayed by a delay circuit (25) including an integrating circuit (25a) and a waveform shaping circuit (25b) for a predetermined time, and then a changeover switch (21).
Is supplied as a switching control signal. In this case, when the switching control signal is low level "0", it is connected to the B side,
When it is at high level "1", it is connected to the A side.

In the example of FIG. 2, when the pause button is pressed at time t ₁ in order to perform slow reproduction (frame-advance reproduction) by, for example, a shuttle dial (not shown), as shown in FIG. 3D, the system controller ( Slow control signal S from 20)
₃ goes from the low level “0” to the high level “1” at this time t ₁ . The signal supplied to the change-over switch (21) becomes high level "1" from the low level "0" at the time t ₂ which is delayed a predetermined time shown in Figure 3 E. Although not mentioned above, the delay time of the delay circuit (25) is the time until the capstan is completely in the pause state. Since the signal supplied to the changeover switch (21) changes from the low level “0” to the high level “1” at the time t ₂ , the changeover switch (2)
1) it is switched at the time t ₂ from the B side to the A side, from the state control pulse CTL is supplied to the tape position counter (23), the step pulse P _S is supplied to the tape position counter (23) To be in a state.

In the above state, when the user operates the shuttle dial, the system controller (20) outputs a step pulse P _S as shown in FIG. 3B, and the correction circuit (24) causes the step pulse P _{S to} be output as shown in FIG. As shown in C, the pulse width is corrected and then supplied to the tape position counter (23) via the fixed terminal on the A side of the changeover switch (21).

Further, slow reproduction is terminated by the operation of the shuttle dial, when releasing the pause state when t _3, as shown in FIG. 3 D, the slow control signal S ₃ of the system controller (20), the time t ₃ Then, the high level "1" changes to the low level "0". Further, the delay circuit (25) delays only the rising edge, and the signal supplied to the changeover switch (21) also changes from the high level “1” to the low level at the time point t ₃ as shown in FIG. 3E. It becomes "0". Therefore, the changeover switch (21) is changed over from the A side to the B side at this time t ₃ , and the control pulse CTL changes the tape position counter (2).
It is returned to the state supplied to 3).

The example of FIG. 2 operates as described above, and FIG. 3A shows the magnetic head.
Although the control pulse CTL is reproduced in (22a), even if the control pulse CTL is missing (shown by a broken line) during slow reproduction, during slow reproduction, instead of the control pulse CTL, a step pulse (first pulse) is generated. Since the tape position counter (23) is supplied to the tape position counter (23), no miscount occurs in the tape position counter (23). FIG. 3F shows the pulses supplied to the tape position counter (23).

The control pulse CTL and the step pulse (3rd
The phase shift (shown in FIG. C) does not cause any particular problem. That is,
Since this pulse is a pulse for the counter only, if there is one pulse in one frame, the phase shift does not cause any particular problem.

〔The invention's effect〕

According to the present invention described above, during slow playback, a step pulse is supplied to the tape position counter to prevent a count error due to a missing control pulse. As compared with the frequency-divided type, a frequency dividing circuit is not required, so that the circuit becomes simple, the substrate area is greatly reduced, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a specific block diagram thereof, and FIG. 3 is a diagram for explaining the operation of the example of 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, and (2
2) is a control pulse detection block, and (23) is a tape position counter.

Claims (1)

[Claims] 1. In a reproducing apparatus capable of slow reproduction and controlling the capstan motor by a step pulse during the slow reproduction, a control pulse reproduced from a magnetic tape and the step pulse are switched to a tape position counter. A reproducing apparatus provided with a changeover switch for supplying the step position pulse to the tape position counter during slow reproduction and the control pulse during other reproduction.