JPS6240653A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent a control signal after mode discrimination from being disturbed by applying the mode discrimination on the way of write or erasure and stopping the write or erasure when a mode change is detected. CONSTITUTION:When a prescribed time elapses from the operation start point of time on the way of write or erasure, a switch circuit 36 is switched forcibly to the position of a reproducing terminal PB and this state is kept for some time. An output of a head 1 is fed to a mode discrimination circuit 39 in the reproducing state to discriminate the mode. The discrimination output is fed to a system controller 31 and fed to an alarm means 40. When any mode change exists, a signal from the system controller 31 stops the generation of a control signal from a control signal control circuit 32 to stop forcibly write or erasure and an alarm is raised. When the circuit 39 detects no mode change, the write or erasure is restarted.

Description

[Detailed description of the invention] The present invention will be explained in the following order.

A. Field of industrial application B. Summary of the invention C. Prior art D. Problems to be solved by the invention E. Means for solving the problems (Fig. 1) F. Effect G. Description of the block diagram of embodiment G1 (Second Figure) G2 Explanation of the operation of the first embodiment (Figures 3 and 4) G3 Explanation of the operation of the second embodiment (Figure 5) The present invention relates to a recording/reproducing apparatus having a control signal track, in which an index signal used for cueing etc. can be multiplexed recorded on the control signal.

B. Summary of the Invention The present invention provides a method for writing or erasing an index signal during playback in a device that can record an index signal on a control signal track by changing the duty factor of the control signal. The writing or erasing operation is stopped during a certain period in the middle of the entire writing or erasing operation time, and the speed mode is determined during that period, and the speed mode is changed within the writing or erasing period according to the output of the determination. This is to prevent the subsequent control signals from being disturbed.

C. Prior Art Conventionally, a VTR is known in which an index signal for cueing, etc. is recorded superimposed on a control signal, and this is extracted during high-speed playback to enable automatic cueing. In this case, the index signal is superimposed on the control signal by changing the duty factor of the signal.

That is, the control signal is generally a 30 Hz rectangular wave with a duty factor of 50%, as shown in FIG. 6A, and for example, its rising point is used for tracking servo during reproduction.

Therefore, the frequency of the control signal and the phase at the rising edge cannot be changed. Therefore, as shown in Figure 6B,
A control signal is a signal in which the frequency and rising phase are unchanged, but the falling point is changed.In other words, a control signal is a signal with a changed duty factor.For example, a signal with a duty factor of 20% is used as an index signal. .

By the way, when recording a video signal, this index signal can be recorded at the beginning of recording or at the beginning of each event, or it can be written at a desired position on a recorded tape without being played back at a later point in time. In addition, the written index signal can be erased.

FIG. 7 shows an example of a control signal and index signal recording and reproducing system having such a function.

(1) is a fixed head for control signals, (2) is a recording amplifier, and (3) is a waveform shaping circuit that shapes the playback output of head (1) to obtain a rectangular wave output.・It is formed by a trigger circuit.

(4) is a current supply circuit that forms a current source that generates a recording current to be passed through the head (11); (5) is a current supply circuit that controls the direction and duration of the recording current that is passed through the head (1) in the recording amplifier (2); This is a switch control circuit. Also, (6) is a recording index forming circuit for supplying an index signal to the head (11) at the start of recording.

(7) is an integration circuit, and (8) is a level comparison circuit. During reproduction, the index signal is extracted from the output of the head (1) by these circuits (7) and (8).

Further, (9) is a system controller (hereinafter abbreviated as system controller), which includes a microcomputer.

The QOI is an index controller having a microcomputer that generates a signal for controlling the writing or erasing of an index signal during reproduction in synchronization with the reproduction control pulse CTL.

In the above configuration, during playback when the playback switch (11) connected to the system controller (9) is turned on, both the signals IDWR and IDER from the index controller 00) are always "0", and therefore the switch The circuit (15) is turned on. In addition, these signals IDWR
and IDER are supplied to the switch control circuit (5), and terminals (2a) and (2) of the recording amplifier (2)
The inside of b) is configured as shown in FIG. 8A during this reproduction. Therefore, the playback output CTr of head (1)
, (Fig. 9A) is supplied to the waveform shaping circuit (3), which produces a rectangular wave signal that rises to "1" at the rising pulse of the output CTL and becomes "0" at the falling pulse of the output CTL. SB (B in the same figure) is obtained.

During this reproduction, the switch (16) is switched to the PB side by a switching signal from the system controller (9), and the rectangular wave signal SB is output to the terminal (17) and sent to a servo circuit or the like.

Further, the rectangular wave signal SB is also supplied to an integrating circuit (7), which integrates the period of rOJ, and its integral output is supplied to a level comparison circuit (8). Since the control signal has a duty factor of 50%, its integrated output does not exceed the threshold value of the level comparison circuit (8), but when it is an index signal, the period of "0" is 80%, so When the integral output exceeds the threshold value, the index signal is detected and the detected output is led out to the terminal (18), which is connected to, for example, the system controller (9).
During high-speed playback, the tape is stopped at the point of detection and cue is performed.

Next, we will explain the recording time when the recording switch (12) is turned on. At this time, the recording mode signal RECM7!
l (supplied to the switch control circuit (5), the internal connections of the terminals (2a) and (2b) of the recording amplifier (2) isometrically connected to the four switches SW as shown in FIG. 8B.
1 to SW4.

In FIG. 8B, the current source (21) turns on the transistor Q1 of the circuit (4) when the signal C0NT supplied from the index controller 0ω to the current supply circuit (4) becomes "1". This is the current HC supplied to the recording amplifier (2) by turning on the transistor Q2.

The four switches SW1 to SW4 are switched to switches SWI, SW2, . Switches S W 3 and S W 4 are turned on and off in combination, and the direction of the current flowing through the head (11) is changed, so that it is recorded on the tape in a state like the signal CTL in FIG. 9A.

At the start of this recording, an index signal is always automatically recorded. That is, the switch (16
) is switched to the REC side for a short period of time at the start of recording by a switching signal from the system controller (9), and the recording control signal SC from the terminal (22) (C
) is supplied to the recording index forming circuit (6) via this switch (16). From this, an index signal SD (FIG. 9D) with a duty of 20% synchronized with the recording control signal SC is obtained.
W□SW2 and switches 5W3-3W4 are switched, and an index signal is recorded on the tape.

During this period, during high-speed reproduction, this index signal is processed by the above-mentioned integrating circuit (7) and level comparing circuit (8).
A period as long as you can know, for example 1 in tape length.
It is said to be 6 cm.

Also, in this case, the index signal can be written at a predetermined position during the recording operation, and when the index mark inch (13) is turned on, from the first rise of the control signal SC counting from that point, Signal ID from index controller αQ
Both the WR and C0NT signals rise, and then the index signal S
D (FIG. 9D) is written in that position.

Next, a case will be described in which an index signal is written before playback.

FIG. 10A shows the playback output CTL from the head (11).During playback, when the index mark inch (13) is turned on, from the first rise of this playback output CTL counting from there, B and C in the same figure Signals fDWR and C0NT are obtained from the index controller αω at the timing shown in FIG. One cycle T
The period from the 10% position to the 80% position is rlJ, and the other periods are "0", and when this signal IDWR is "0", the recording amplifier returns to the above-mentioned playback state (see Fig. 8). A) When the signal IDWR is "1", it is in a recording state (FIG. 8B), and during this "1" period, it is in a state in which a recording current can be supplied to the head (11), that is, in a write standby state.

In this write standby state, when the signal C0NT becomes "1", the transistor Qt of the current supply circuit (4),
Q2 is turned on, a recording current HC flows through the head (1), and writing is performed. The signal C0NT is as shown in C of the same figure.
The signal C0NT becomes "1" from the 20% position to the 60% position of the period T with reference to the rising pulse position of the signal CTL. In other words, the signal C0NT becomes "1" during the write standby state, and this causes the current supply circuit ( 4), the recording current H
C (D in Figure 10) flows into the head (11).A fall of this current HC is recorded at the duty factor 20% position.
The falling edge of the signal CTL at the % position is erased,
As a result, an index signal is written.

At this time, the signal II from the index controller Ql
)El? remains at "0", and therefore the switch (4S) of the current supply circuit (4) is turned on.

Therefore, even if the signal C0NT becomes "0", the capacitor (4C
), the current HC rises slowly.

This is because the writing of the control signal and index signal is performed by changing the direction of the current flow in the head +1), so when the rectangular wave current of the signal C0NT is passed as the current HC, a fall occurs at the 60% position. It will be recorded and cause servo disturbance later.
This is to reduce the influence on the recording waveform.

Note that even when writing this index signal,
The recording and reproducing device performs reproduction servo so that the reproduced image can be seen. In this case, since the switch (5) is controlled by the signal IDWR, the output PBC (FIG. 10E) of this switch (15) provides only the rising pulse of the output CTL of the head (1). Therefore, in this case, in order to obtain the rectangular wave output necessary for the servo, the signal ID is differentiated by a capacitor (23) and a resistor (24), and the differentiated pulse IDP
is supplied to the waveform shaping circuit (3). Therefore, the input signal INF (FIG. 10F) of the waveform shaping circuit (3) is
It is a combination of pulse PBC and pulse IDP. Therefore, the output CO of the circuit (3) becomes a rectangular wave as shown in FIG. 1G, and its rising edge can be used as a servo reference. Note that during this writing, the switch (16) is always switched to the PB side.

Next, during the playback operation, press the index erase switch (14).
) is turned on and the previously recorded index signal is erased.

This erasure of the index signal is performed by a duty factor of 2
0% index signal waveform with duty factor 50
% control signal waveform.

At this time, first, a position where the index signal is to be erased is searched, and the erase operation is performed in the searched index signal recording portion as follows.

The index controller 0 outputs a signal IDER which becomes "1" between the 5% position and the 80% 0% position of the period T, based on the rising time of the playback output CTL of the head (11 (A in Figure 1)). (Figure 10H) is obtained,
This is supplied to the switch control circuit (5), and the head (11) becomes in a state where current can be supplied during the "1" period, similar to when writing.

On the other hand, the signal C0 from the index controller 00)
As shown in FIG. 10I, during erasing, NT is 10% 0% of the period T based on the rising edge of the signal CTL.
It becomes rlJ between position 50% and 0% position. Therefore, the transistor transistor Q2 of the current supply circuit (4) is turned on during this period, and the current HC flows through the head f1) during this period, as shown in FIG. 10J. However, when erasing this,
As is clear from FIG. 1O, a current flows in the head in the opposite direction to that during writing.

Therefore, the rising pulse at the 20% 0% position is erased, and the falling pulse at the 50% 0% position is recorded, thereby erasing the index signal.

Note that during this erasing, it is necessary to flow a rectangular current having the same waveform as the signal C0NT as the current HC, so the switch (4S) is turned off by the signal IDER when this current is supplied.

Even during this erasing, the signal IDEI? is the capacitor (
23) and (24) to form a differential pulse IDP,
This is the rising pulse PB from the switch (15)
C (E in the figure) is added to the input pulse INF (K in Figure 1O) of the waveform shaping circuit (3), and the signal shown in the figure is obtained as the waveform shaping output CO, which is used as the servo reference. It is led out to the terminal (17) as a signal.

The above erasing operation is performed over a slightly longer portion including the writing portion of the index signal.

D Problems to be solved by the invention The VTR has, for example, β1. It generally has a plurality of speed modes such as β■ and β■, and it is often the case that a plurality of programs are recorded in a plurality of different speed modes on one tape.

In this case, the frequency of the control signal recorded is 30
Even if the frequency is constant at Hz, the pinch of the rising and falling traces of the control signal recorded on the control track of the tape differs depending on the speed mode.

Therefore, during playback, when playing in a certain speed mode, the cycle of the playback control signal will change if a part is recorded in a different speed mode.
Using this, the mode is determined, and the determined output is supplied to the system controller (9) to automatically switch the device to that mode.

By the way, when writing or erasing the index signal during the above-mentioned playback, the writing or erasing of the index signal is performed over the required time as described above, but there are some recordings in which the speed mode changes during that time. Some parts may be played back.

In such a case, if the index signal is written or erased in the same mode even though the speed mode has changed, the control signal of that part will be disturbed, and as a result, the control signal of the disturbed part will be The playback image becomes completely unwatchable.

In such a case, the terminal (17
), the signal extracted as a servo signal becomes
If there is a large disturbance in the Hz signal, the servo lock will be lost, so by monitoring this and immediately stopping the writing or erasing operation, it is possible to prevent the control signal in that area from being disturbed.

However, in the above case, before writing and erasing the index signal, the signals IDB and IDER
(Of the reproduction control pulse CTL from 11, the polarity, for example, the rising signal part, which is used as a reference for the reproduction servo, is taken out in the reproduction state, and the servo reference signal CO is formed using these signals IDWR and IDER. I try to do that.

Therefore, when writing or erasing, the speed mode changes from βI to β■ (speed ratio 2
:1), as is clear from the figure, the servo reference signal CO is obtained without any change, and the servo remains in the locked state. Therefore, the control signal for the β■ peach portion will be disturbed.

E. Means for Solving the Problems FIG. 1 is a block diagram mainly showing the functions of an example of the device of the present invention.

In FIG. 1, (31) is a system controller, to which are connected a playback switch (11), a recording switch (12), an index mark switch (13), and an index erase switch (4) in the same manner as described above.

When the switch (13) or (14) is turned on, the index is written or erased.
At this time, the control signal generation circuit (32) outputs the aforementioned control signal IDWR or IDHR, C0NT, etc. to the stop means (33).
) to the index signal/erase signal generation circuit (34
). This circuit (34) corresponds to the switch control circuit (5), the recording amplifier (2), and the current supply circuit (4) in the example shown in FIG.

The control signal forming circuit (32) also provides a switching signal for the recording/reproduction changeover switch (36). This switching signal corresponds to the signal IDWR or IDER in the example in FIG. 6, and is supplied to the switch circuit (36) through the OR gate (37) to switch the switch circuit (36).
As a result, an index signal is written and an erase signal is also written.

Then, during the write or erase operation, when a predetermined period of time has elapsed from the start of the operation, a signal from the system controller (31) is supplied to the switch circuit (36) via the OR gate (37). Switch circuit (36)
is forcibly switched only to the reproduction side terminal PB. This reproduction state is then maintained for some time. Further, the stopping means (33) prevents the control signal forming circuit (32) from supplying the control signal to the generating circuit (34) for this certain period of time. And in this state of reproduction,
The output of the head (11) is supplied to the mode discrimination circuit (39) via the gate circuit (38), and the mode is discriminated by detecting, for example, the period of the reproduction control pulse.Then, this mode discrimination output is sent to the system controller. (3
1) and 1? [1 means (40) is supplied, and when there is a mode change, this system controller (31)
The signal from the control signal control circuit (32) stops the generation of the control signal, and the writing or erasing operation is forcibly stopped and an alarm is issued.

When the mode discrimination circuit (39) does not detect a mode change, a signal from the system controller (31) is used to stop the stop means (3).
The stoppage of the supply of the control signal to the control signal generation circuit (34) due to step 3) is released, and the writing or erasing operation is restarted. At the same time, the gate circuit (38) is closed and the mode discrimination operation is stopped.

When the system controller (31) detects a mode change based on the mode discrimination output, it accordingly switches the tape speed to that mode and transmits the write or erase control signal for that mode to the control signal forming circuit (31). 32) After that, the stopping operation of the stopping means may be canceled and the writing or erasing operation may be restarted.

It should be noted that the above-mentioned period during which writing or erasing is stopped may be a period sufficient for mode discrimination, or a period long enough for mode discrimination and mode switching.

F Effect During the writing or erasing operation, it is always determined whether there is a mode change.

Then, when a mode change is detected by mode discrimination, the write or erase operation is stopped, or the write or erase operation is performed according to the mode, so that the control signal after mode discrimination is not disturbed.

G Explanation of the block diagram of Embodiment G1 FIG.
Portions corresponding to those in the illustrated example are designated by the same reference numerals.

In this example, from the system controller (9), only a few frame sections from about 1/2 of the entire interval of the index signal writing or erasing operation during playback (for example, 16 cn + minutes of tape length) are set to "1". A signal SPB is generated, and this signal SPB is supplied to the switch (15) through the OR gate (25) and also to the switch control circuit (5).

Signals IDWR and rDER are also connected to this OR gate (
25) to the switch (15).

Further, a control signal output through a switch (16) is supplied to a mode discrimination circuit (26), and the discrimination output thereof is supplied to a system controller (9).

Further, an i-information means (27), for example, a speaker is provided, and when required by the system controller (9), this speaker (27) is provided.
7) It is designed to emit a more alarm sound.

The rest of the structure is the same as the example shown in FIG.

G2 Explanation of Operation of First Embodiment FIG. 3 is an example of a flowchart of a program executed by the microcomputer of the system controller (9) when writing an index, and will be described below.

First, during playback, when the switch (13) is turned on as shown in Figure 4, the controller (00) is sent from the system controller (9).
The signal INDX is supplied to , and the write operation starts (
step (101)). That is, the index controller 0 generates control signals IDWR and C0NT as described above, and a write operation is performed.

Then, when it is determined that it is half of the total write operation period TI (step (102)), the signal rNDX becomes "0" and the write operation is temporarily stopped (step (103) ''). At this time, the aforementioned signal SPB from the system controller (9) becomes "1",
When the switch (5) is turned on, the head (11) is turned on.
The peripheral area of the device is in the connected state of the playback state. Therefore, a reproduction control signal is obtained from the switch (16), which is supplied to the mode discrimination circuit (26) to discriminate the mode (step (104)).

This determination output is then supplied to the system controller (9), and it is determined whether there is a mode change (step (105)).

If there is no mode change, the signal INDX returns to "1" after a period of several frames from the moment of suspension, and the signal SPB
becomes "0" and the write operation is restarted (step (106)).

Then, when the end of the writing period is detected (STE knob (107)), the IF writing operation ends (
step ctoa)).

On the other hand, when it is detected by the discrimination output that a mode change has occurred, the signal INDX is no longer "
1", the write operation is forcibly stopped and the signals IDIt4R, C0 from the index controller a
NT becomes the waveform in the i11 constant playback mode (step (109)"). Then, an alarm sound is emitted from the speaker (27) (step (110)).

Note that the period during which the write operation is interrupted by setting the signal SPB to "1" may be a period sufficient for mode discrimination.

When erasing the index signal, the switch (14) is turned on, a position to be erased is searched for, and then the erase signal is written in the same manner as in the flowchart of FIG.

G3 Operational Description of Second Embodiment In the first embodiment, writing of the index signal or erase signal is immediately stopped when a mode change occurs, but the following may be used.

FIG. 5 is a flowchart of the main part, in which steps [111) and [112] are provided in place of steps (100) and (110) in the flowchart of FIG.

That is, in this example, the mode change is performed by a step (
105), the system controller (9) switches the device to that speed mode in step (Ill), and then the system controller (9) supplies the mode signal to the index controller OI, and the system controller (9) supplies the mode signal to the index controller OI. The control signals IDWR and IDER should also be set in accordance with the mode (step (
112) ). Thereafter, the process proceeds to step (106) and writing is resumed. Therefore, even if there is a mode change, the correct index signal or erase signal according to the mode is recorded.

In this example, the period to be stopped may be long enough to determine the mode and switch the mode. Also, in this example, no alarm may be issued.

Note that the i-axis means may not be sound, but may be light, such as a flashing lamp.

Note that the point in time to stop writing or erasing is not limited to the 1/2 point, but may be at any point within the operation period.

H Effects of the Invention According to this invention, even if an index writing or erasing operation is performed on a portion where the mode changes, the mode is determined at any point during the operation, and the subsequent control signal is determined based on the output of the determination. Since the screen has been devised so as not to be disturbed, when this is played back, the period during which the screen is disturbed is less than 1/2 of the index writing or erasing time.

Since the mode is correct at the start of writing and erasing, only a small portion of the control signal is disturbed.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram of an example of the main parts of the device of this invention.
FIG. 2 is a block diagram of an embodiment of the main part of this invention device;
Figures 3 to 5 are diagrams for explaining the operation of the embodiment shown in Figure 2, Figure 6 is a diagram showing the recording signal waveform of the control track, and Figure 7 is a block diagram of an example of the main part of the conventional device. figure,
8 to 10 are diagrams for explaining the example in FIG. 7. (1) is a magnetic head for control signals, (32) is a control signal forming circuit, (33) is a stop means, (34) is an index signal/erase signal generation circuit, and (39) is a mode discrimination circuit. Clay LA sentence size n field 1st figure name - 1 included st@; xvtr-t-sound pfu〇-thousand←
- Figure 5 Control Track 4Ki Official Name's Monthly Figure 6 Figure 1 Self (East, Regeneration Time Chart Figure 9

Claims (1)

[Claims] 1. The recording medium has a plurality of speed modes with different transport speeds, a control signal is recorded by a fixed head on a control track on the recording medium, and an index signal is multiplexed to this control signal. In a recording and reproducing apparatus capable of recording data in a reproducing state, means for receiving a control command in a reproducing state and generating a control signal for writing or erasing the index signal in the control track according to a speed mode at that time; means for receiving a control signal and writing or erasing an index signal in the control track according to the speed mode at that time; and writing or erasing operation for a certain period from an arbitrary point within the total operation time of the writing or erasing. means for discontinuing the writing or erasing, means for determining the speed mode during the above-mentioned certain period, and means for prohibiting the writing or erasing and displaying a warning display when the determined speed mode is different from the current speed mode. Recording and playback device. 2. It has a plurality of speed modes in which the recording medium is transported at different speeds, and a control signal is recorded by a fixed head on a control track on the recording medium, and an index signal can be multiplexed and recorded on this control signal. In the recording and reproducing apparatus, the recording and reproducing apparatus includes: means for generating a control signal for writing or erasing the index signal in response to a control command in a reproducing state; means for writing or erasing a signal; means for suspending the writing or erasing operation for a certain period from an arbitrary point within the total operation time of the writing or erasing; and means for determining the speed mode during the certain period; means for switching the speed mode when the determined speed mode is different from the current speed mode; means for switching the index signal to one that matches the speed mode; and the writing or erasing after the speed mode is switched. A recording/reproducing device comprising: means for restarting.