JP2526794Y2 - Magnetic tape recording / reproducing device - Google Patents

Description

The present invention relates to a magnetic tape recording and reproducing apparatus, and more particularly to a magnetic tape recording and reproducing apparatus capable of muting an audio signal.

[Conventional technology]

In the DTA, a mute switch is provided between the head and the recording / re-amplifier, and the system microcomputer outputs a mute on / off signal when necessary, such as during recording, and outputs a signal from the recording / re-amplifier for a predetermined period. The input can be muted.

This is used, for example, when the signal processing circuit is set to the recording mode and outputs a recording signal including the subcode and the PCM audio signal, but does not want to record anything on the tape due to a pause or the like.

When the signal processing circuit has a mute terminal, the system microcomputer can output a mute on / off signal to make the PCM audio signal itself mute data for a predetermined period.

[Problems to be solved by the invention]

However, in the conventional DAT, since the system microcomputer outputs a mute on / off signal at an arbitrary time, the signal recording is stopped when a certain part of the track is recorded with respect to the mute switch, or a certain track is stopped. Signal recording is restarted in the middle of the process.

If the discontinuous recording is performed in the middle of the track in this way, an error occurs in the data at the discontinuous point, and a noise sound is generated when the data is reproduced.

As for the signal processing circuit, if a mute on / off signal is input to the signal processing circuit during recording on a certain track, an erroneous PCM audio signal may be generated.

The present invention has been made in view of the drawbacks of the related art, and has as its object to provide a magnetic tape recording / reproducing apparatus that can avoid turning on / off a mute in the middle of a track.

It is another object of the present invention to easily mute a predetermined number or an arbitrary number of tracks and frames.

[Means for solving the problem]

In this invention, a magnetic tape recording / reproducing apparatus having a mute unit for turning on / off a mute for an audio signal in accordance with a mute on / off signal, and a switching pulse generating unit for generating a switching pulse in accordance with the rotation of a rotary cylinder. When a mute-on signal is input from the outside, the mute-on synchronization section outputs a mute-on signal to the mute section in synchronization with the switching pulse generated by the switching pulse generation section. A counting unit that counts the switching pulses generated by the generation unit; and a mute-off signal generation unit that outputs a mute-off signal to the mute unit in synchronization with the switching pulse when the counter counts a predetermined set value. It is characterized by having To have.

Further, another magnetic tape recording / reproducing apparatus according to the present invention is characterized in that the set value of the mute-off signal generator can be changed.

〔Example〕

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

FIG. 1 is a block diagram showing a DAT according to the present invention.

The audio sample data input terminal and the microcomputer 12 are connected to the signal processing circuit 10, and in the recording mode, the audio sample data and the subcode are input to the signal processing circuit 10 to perform predetermined signal conversion and output as a recording signal. Is done.

The output side of the signal processing circuit 12 is connected to an A head 20 and a B head 22 via an amplifier 14, a mute switch 16, and a changeover switch 18.

The mute switch 16 turns mute on / off according to a mute-on signal (“H” level) and a mute-off signal (“L” level) input from outside.

When the mute is off, the recording signal output by the signal processing circuit 12 is sent to the head, but when the mute is on, the output of the recording signal to the head is stopped.

The rotation of a rotary cylinder (not shown) on which the A head 20 and the B head 22 are mounted is detected by a switching pulse generator 24, and rises at the tape scanning start timing of the A head 20 and at the tape scanning start timing of the B head 22. It is output as a falling switching pulse (SWP).

The switching pulse is sent to the changeover switch 18 to switch the head.

A D flip-flop 26 as a synchronization circuit is connected to the mute switch 16 on the input side of the mute on / off signal.

That is, the Q terminal of the D flip-flop 26 is connected to the mute switch 16 as a mute on / off signal output terminal, and the CK terminal is connected to the output side of the switching pulse generator 24.

The D terminal is connected to the mute output terminal of the microcomputer 12.

An operation unit 28 and a tape running / mechanical control unit (not shown) are connected to the microcomputer 12, and based on a predetermined program stored in the ROM, recording mode control and pause mode control are performed on each part of the DAT according to a user operation. The sub-code is output to the signal processing circuit 10 in the recording mode, and the mute control is also performed when the recording mode is set to the pause mode.

Next, the operation of the above embodiment will be described with reference to the time chart of FIG.

Here, each part of the DAT is set in the recording mode in advance, the tape is running at a predetermined recording speed, and the signal processing circuit
It is assumed that 10 performs a predetermined signal conversion process on the audio sample data and the subcode and outputs the signal as a recording signal.

When the microcomputer 12 is outputting the "L" level mute-off signal during normal recording, the D flip-flop 26 latches the D input every time the switching pulse rises, and the "L" level mute-off from the Q terminal. The signal is output to the mute switch 16.

For this reason, the recording signal output from the signal processing circuit 10 passes through the mute switch 16, and the half cycle in which the switching pulse rises is sent to the A head 20, and the half cycle in which the switching pulse falls is sent to the B head 22. It is sent out and recorded alternately on the track.

When the user performs a pause key operation in this state, the microcomputer 12 outputs an "H" level mute-on signal, and then performs pause control on the tape running / mechanical control unit to stop the tape running.

When a mute-on signal is input from the microcomputer 12, the D terminal input of the D flip-flop 26 changes to "H", but the Q terminal output is still "L".

Next, when the rising of the switching pulse is input, D
The flip-flop 26 changes the Q terminal to “H” and outputs the signal to the mute switch 16 as a mute-on signal.

The mute switch 16 stops outputting the recording signal to the head immediately after inputting the mute-on signal.

For this reason, the recording on the tape is stopped from the point in time when the A head 20 starts scanning, so that an error in the recorded data does not occur in the middle of the track.

Thereafter, when the user performs a pause release operation, the microcomputer 12 restarts the tape running and outputs an "L" level mute off signal.

As a result, the D terminal input of the D flip-flop 26 falls to "L", but the Q terminal output still remains at "H".

Next, when the rising edge of the switching pulse is input,
The Q terminal output changes to “L” and is output as a mute off signal.

Therefore, the mute switch 16 releases the mute from the scanning start point of the A head 20, and the signal recording is restarted from the end of the track.

According to this embodiment, the mute switch 16 turns on / off the mute when the A head 20 starts scanning the track.
Since the signal is turned off, erroneous data is not recorded in the middle of the track, and no noise is generated during reproduction.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 3 shows a case where the mute is turned on / off digitally.

The signal processing circuit 10A receives the audio sample data and the subcode, performs a predetermined signal conversion process, outputs the signal as a recording signal, and outputs a recording signal when an “H” level mute-on signal is input to the mute input terminal. PCM of signal
It has a function of converting an audio signal into mute data and outputting it.

The output side of the signal processing circuit 10A is connected to an A head 20 and a B head 22 via an amplifier 14 and a changeover switch 18.

The output terminal of the counter circuit 30 is connected to the mute input terminal of the signal processing circuit 10A.

The output side of the switching pulse generator 24 is connected to the clock terminal of the counter circuit 30.

The output side of the microcomputer 12A is connected to a control terminal including a data input terminal and a gate terminal of the counter circuit 30.

The counter circuit 30 sends a mute on / off signal to the mute input terminal of the signal processing circuit 10A connected to the output side in accordance with the mute control of the microcomputer 12A.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG.
This will be described with reference to the time chart of FIG.

In advance, the signal processing circuit 10A is set to the recording mode,
It is assumed that a recording signal is created and output based on digital audio sample data input from the outside and a subcode input from the microcomputer 12A.

When the digital mute is not applied, the microcomputer 12A does not control the counter circuit 30 (NO in step 40), and the output of the counter circuit 30 is “L”.
Remains.

At this time, the signal processing circuit 10A outputs a PCM audio signal according to the input audio sample data.

When the microcomputer 12A determines that the mute should be turned on under the predetermined condition (determination of YES in step 40), the mode setting of the one-shot operation for the counter circuit 30 (step 42) corresponds to the number of frames to be muted. The count number is preset (step 44), and finally a trigger is output to the gate terminal as a mute-on signal (step 46).

 Here, it is assumed that the count number = 5.

Then, the counter circuit 30 changes the output terminal to “H” from the rising edge of the next switching pulse, and outputs a mute-on signal to the signal processing circuit 10A.

At this time, the signal processing circuit 10A inputs the mute-on signal before the recording signal output for the previous track ends and the recording signal for the next track is output,
All the PCM audio signals in the recording signal output after the A head 20 starts the next track scanning are replaced with accurate mute data.

On the other hand, in the counter circuit 30, the rising input of the switching pulse after the output terminal changes to "H" is counted, and when the rising of the fifth switching pulse is input, the output terminal is dropped to "L". The mute-off signal is output to the signal processing circuit 10A.

Then, after the recording of the mute data is started in the signal processing circuit 10A and the scanning of five frames is completed,
The mute-off signal will be input before the track scanning of the next sixth frame is started, and all PCM audio signals in the recording signal output after the A-head 20 starts scanning the sixth frame. It will be accurate data.

If the preset count number is changed to 7, for example, by control performed on the counter circuit 30 before the mute starts, the complete mute data can be recorded over 7 frames.

If the frame from which the mute data is to be recorded is determined, the mute control for the counter circuit 30 may be performed before the frame scanning is started.

According to this embodiment, only the predetermined control including the preset of the count number is performed on the counter circuit 30, and the mute on / off operation is performed on the signal processing circuit 10A when the A head 20 or the B head 22 is not scanning the track. An off signal can be output, so that there is no possibility that an erroneous PCM audio signal is recorded in the middle of a track.

If the count number preset in the counter circuit 30 is changed, mute data can be recorded over an arbitrary length.

In the case of the embodiment shown in FIG. 3, if the length of the frame to be muted is constant, the use of a counter circuit having a fixed count eliminates the need for presetting the count.

1 and 3, a signal obtained by ORing a switching pulse and an inverted signal of the switching pulse is input to the CK terminal of the D flip-flop 26 and the clock terminal of the counter circuit 30. For example, it is possible to mute each track.

Further, in each of the above-described embodiments, an example during recording is given. However, a mute synchronized with track scanning can be similarly applied during reproduction.

[Effect of the invention]

In the magnetic tape recording / reproducing apparatus according to the present invention, when a mute-on signal is input from the outside, a mute-on synchronization section that outputs a mute-on signal to a mute section in synchronization with a switching pulse generated by a switching pulse generation section, When a mute-on signal is input from the counter, the switching pulse generator then counts a switching pulse generated by the switching unit, and a mute-off signal to the mute unit in synchronization with the switching pulse when the counter counts a predetermined set value. By providing the output mute-off signal generation unit, even if a mute-on / off signal is externally applied at any time, there is no possibility that a mute will generate noise noise in the middle of the track. Further, it is possible to easily mute over a predetermined number of tracks or frames.

Further, since the setting value of the mute-off signal generating section is variable, mute can be easily applied over an arbitrary track length or frame length.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a DAT according to one embodiment of the present invention, FIG. 2 is a time chart for explaining the operation of the D flip-flop of FIG. 1, and FIG. 3 is another embodiment. FIG. 4 is a block diagram showing the configuration of the DAT, FIG. 4 is a flowchart showing the operation of the microcomputer in FIG. 3,
FIG. 5 is a time chart for explaining the operation of FIG. 10, 10A: signal processing circuit, 12, 12A: microcomputer,
16: Mute switch, 24: Switching pulse generator,
26: D flip-flop, 30: counter circuit.

Claims (2)

(57) [Scope of request for utility model registration] 1. A magnetic tape recording / reproducing apparatus comprising: a mute section for turning on / off a mute for an audio signal in accordance with a mute on / off signal; and a switching pulse generating section for generating a switching pulse according to rotation of a rotary cylinder. , A mute-on synchronizer that outputs a mute-on signal to the mute section in synchronization with the switching pulse generated by the switching pulse generator when an external mute-on signal is input, and a switching pulse A counting unit that counts the switching pulses generated by the generation unit; and a mute-off signal generation unit that outputs a mute-off signal to the mute unit in synchronization with the switching pulse when the counter counts a predetermined set value. Characterized by having Magnetic tape recording and reproducing device. 2. The magnetic tape recording / reproducing apparatus according to claim 1, wherein a set value of the mute-off signal generating section is variable.