JPH0614279Y2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention is generally called a video tape recorder, in which an inclined track is formed on a magnetic tape to record a video signal and the recorded magnetic tape. Relates to a magnetic recording / reproducing apparatus for reproducing a video signal from a recording medium, and in particular, prior to a recording operation of the video signal, a head portion of a non-recorded portion of the magnetic tape where the video signal is not recorded is found.
The present invention relates to a magnetic recording / reproducing device capable of performing a so-called blank search.

BACKGROUND ART AND PROBLEMS IN A VIDEO TAPE RECORDER
When recording on a non-recorded portion of a magnetic tape, if a new magnetic tape that has never been used for recording is used, it can be recorded on any portion as it is. When recording is made on a remaining non-recorded portion without erasing the already made recording by using the magnetic tape partially recorded, the magnetic tape is previously recorded before the recording operation for recording the video signal. It is necessary to perform a so-called blank search to find the beginning of the non-recorded area. In performing such a blank search, in the conventional art, for example, while watching a reproduced image obtained on a monitor TV for reproduction, by repeatedly operating an operation key such as fast forward or rewind of a video tape recorder, The search was made for the part where the reproduced image cannot be obtained. However, such an operation is extremely troublesome, and furthermore, there is an inconvenience that it is difficult to perform an accurate and quick blank search by such an operation, and further, when there is no reproduction monitor television. There was a problem that blank search was not possible.

DISCLOSURE OF THE INVENTION In view of the above points, the present invention provides a magnetic recording / reproducing apparatus that is capable of performing the above-described blank search automatically, accurately and quickly, and has improved operability. To do.

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, a magnetic recording / reproducing apparatus according to the present invention uses a reproducing control pulse obtained by a reproducing head for reading a control pulse from a magnetic tape on which a control pulse is recorded corresponding to an inclined track. Between the detecting unit for detecting and the reproducing head for reading the control pulse and the full-width erasing head provided for erasing the signal recorded on the magnetic tape during the time when the reproducing control pulse is not detected in the detecting unit. A time detection unit that detects that the portion corresponding to the travel path length has reached the time required to pass the read head that reads the control pulse and generates a detection output according to the non-recorded portion of the magnetic tape. After the detection output from the time detection unit is obtained, the magnetic tape continues or moves in the traveling direction. It has a tape running control section that reverses and runs in the direction opposite to the playback forward direction, and a counter that is reset according to the detection output from the time detection section, and after that detection output is obtained. When the magnetic tape is running in the direction opposite to the reproduction forward direction, a counter for counting the reproduction control pulses obtained by the reproducing head by a counter, and when this counter counts a predetermined number of reproduction control pulses, And a tape drive unit for stopping the running of the magnetic tape. With such a configuration, it is possible to perform an automatic blank search using the reproduction control pulse.

Embodiment First, a running path of a magnetic tape in an example of the recording / reproducing apparatus according to the present invention will be described with reference to FIG. 1 at the time of recording, and recording was performed by this. The recording mode of the magnetic tape will be described with reference to FIG. In FIG. 1, when the magnetic tape 3 from the supply reel 2 to which a predetermined rotation is given by the driving means 1 travels in the horizontal direction and first passes the full width erasing head 4, the full width erasing head 4 causes the full width erasing head 4 to move. For example, if the magnetic tape is recorded, all recording signals are erased. After that, for example, in the rotary head drum 5,
A substantially half circumference is wound in an oblique direction with respect to the scanning direction of the video head and is made to run. Rotating head drum 5
Is composed of, for example, a rotary drum 5a and a fixed drum 5b.
They are attached at intervals of 180 °. By applying a predetermined number of revolutions, for example, 30 revolutions per second, to the rotating drum 5a, the video head 6 rotates at the same number of revolutions, whereby the magnetic head 3 is slanted with respect to the traveling direction. For example, 60 sloping tracks are formed in the direction from the lower edge of the magnetic tape 3 to the upper edge thereof every second. Further, thereafter, the magnetic tape 3 whose traveling direction is returned to the horizontal direction again by a taper guide or the like (not shown)
However, when the audio signal is passed through the audio and control head portions 7, an audio track is formed at the upper edge of the magnetic tape 3 to record an audio signal, and a control track is formed at the lower edge of the magnetic tape 3 to generate a control pulse. Will be recorded. The control pulse corresponds to the tilted track as used for controlling the frame synchronization of the reproduced video signal, and is, for example, the video head 6
One pulse is recorded for each rotation of. Then, the magnetic tape 3 on which such recording is performed is finally wound up by the winding reel 9 which is given a predetermined rotation by the driving means 8.

Next, a recording mode in the magnetic tape 3 recorded while traveling as described above will be described. Figure 2A shows
An example of a recording mode on such a magnetic tape 3 will be shown. This example is a case where there is a non-recorded portion in which a video signal is not recorded behind the magnetic tape 3 in the running direction. For example, a new magnetic tape which has never been recorded is used. This is the case when recording is done up to the middle. In the case of this recording mode, first, the magnetic tape 3
1 is made to travel in the direction of the arrow x shown in FIG. 1 on the above-described travel route, the video head 6 sequentially forms the inclined tracks 10 on the magnetic tape 3 to record the video signal, and then the audio signal is recorded. An audio track 11 is formed by the audio head 7a that constitutes the control head unit 7, and an audio signal is recorded. Further, a control track 12 is formed by the control head 7b which is arranged integrally with the audio head 7a and constitutes the audio and control head section 7, and a control pulse is recorded.

When a new desired video signal is recorded on the remaining non-recorded portion 13 using the magnetic tape 3 on which such recording is performed, the magnetic tape 3 is generally reproduced after recording. For example, it is not clear whether the position of the non-recording portion 13 is unclear or whether the magnetic tape 3 has the non-recording portion 13 because it is running for the recording. Prior to the operation, it is necessary to find the beginning of the unrecorded area 13.

FIG. 2B shows another example of the recording mode on the magnetic tape 3. In this example, a magnetic tape which has already been recorded is used, and the old record is erased by the full-width erasing head 4. This is the case when a new record of is recorded halfway. In this case, when the recorded magnetic tape 3 is used and new recording is performed on it, first, the old recording portion 14 is sequentially erased by the full-width erasing head 4, and a desired new recording is performed on the erased portion. However, when new recording is interrupted, as shown in FIG. 2B, the full width erasing head 4 is provided between the old recording portion 14 and the portion where the new inclined track 10 is formed. Erasing part, that is,
A non-recording portion 13 'is formed. At this time, since the full-width erasing head 4 and the control head 7b are arranged apart from each other, the control pulse is omitted in the control track 12 between the old recording portion 14 and the portion where the new inclined track 10 is formed. I have a section. The length T of the lacking portion of the control pulse corresponds to the length of the traveling path between the full width erasing head 4 and the control head 7b, and the length of this traveling path is the full width erasing head 4 and the control head 7b. Position, and the diameter of the rotary head drum 5 around which the magnetic tape 3 is wound.

Then, when continuing the new recording which has been once interrupted, it is first necessary to find the beginning of the non-recording portion 13 'between the old recording portion 14 and the portion where the inclined track 10 is formed by the new recording. Becomes

In the recording / reproducing apparatus according to the present invention, the second
A blank search for finding the beginning of the non-recorded portion formed in the recording mode of the magnetic tape 3 as shown in FIGS. This is done automatically by using a pulse. That is, the control pulse is recorded along with the recording portion of the video signal on the magnetic tape 3, and conversely, the control pulse is not recorded in the non-recording portion where the video signal is not recorded. It is used to perform a blank search.

FIG. 3 shows a main part of an example of a magnetic recording / reproducing apparatus according to the present invention having a magnetic tape running path as shown in FIG. First, to explain the configuration of this main part, one output end of the running command unit 21 is connected to one input end of the AND gate 22, and the output end of the AND gate 22 runs the magnetic tape. It is connected to a first output terminal 23 which is connected to a running / stopping control circuit (not shown) of the tape drive section for stopping. The other output end of the running command unit 21 is connected to one input end of the exclusive OR gate 24, and the output end of the exclusive OR gate 24 is connected to a running direction control circuit (not shown) of the tape drive unit. Connected to the second output terminal 25.

On the other hand, the output terminal of the blank search command unit 26 is connected to one input terminal of the AND gate 27, and the other input terminal of the AND gate 27 operates as a reproducing head for reading a control pulse during reproduction.
Is connected to a terminal 28 to which a reproduction control pulse from The output end of the AND gate 27 is connected to the input end of the control pulse detection circuit 29, and the output end of the control pulse detection circuit 29 is connected to the reset end of the timer 30. The output end of the timer 30 is connected to one input end of the AND gate 31, and the output end of the AND gate 31 is connected to the reset end of the counter 32. The output end of the AND gate 27 is connected to the input end of the counter 32, and the output end of the counter 32 is connected to the AND gate 2
2 is connected to the other input terminal.

The output terminal of the timer 30 is connected to one input terminal of the AND gate 33, and the output terminal of the AND gate 33 is connected to the other input terminal of the exclusive OR gate 24.
The output terminal of the exclusive OR gate 24 is connected to the other input terminal of the AND gate 33 and also connected to the other input terminal of the AND gate 31 via the inverter 34.

Next, the operation of the essential parts of an example of the magnetic recording / reproducing apparatus according to the present invention configured as described above will be described with reference to the blank search mode shown in FIG.

The blank search mode shown in FIGS. 4A and 4B is a case in which a blank search operation is performed in a so-called rewinding magnetic tape that allows the magnetic tape to run rapidly in the direction opposite to the reproduction forward direction. Then, first, the operation of the above-described main part will be described with reference to these blank search modes.

In order to take the rewinding state, the high-level signal S1 is supplied to one input end of the AND gate 22 from one output end of the travel command unit 21. The other input terminal of the AND gate 22, the output terminal of the counter 32 is supplied with the signal S2 to take normally high, thereby a high level signal S ₃ to the output terminal of the AND gate 22 is obtained. When this high-level signal S ₃ is supplied to the first output terminal 23, the tape drive unit is brought into a state of running the magnetic tape.

On the other hand, the low-level signal S ₄ is supplied to the one input end of the exclusive OR gate 24 from the other output end of the travel command unit 21. The other input terminal of the exclusive OR gate 24 is supplied with the signal S ₅ taking normal low level from the output terminal of the AND gate 33, thereby a low level signal to the output terminal of the exclusive OR gate 24 S ₆ Then, the tape drive section is made to run the magnetic tape in the rewound state. In this way, the rewinding state is obtained.

When the blank search is performed in such a state, the high-level signal S ₇ is output from the output end of the blank search command unit 26.
Is supplied to one input terminal of the AND gate 27. First, in the case of the embodiment shown in FIG. 4A, the control head 7b is located at the starting point C ₁ , and the control track 45 on the magnetic tape, for example, the old recording section 14 shown in FIG. Equivalent to the control track section,
The control pulse 47 of the first control pulse recording unit 46 is read by the control head 7b,
The reproduction control pulse P _c is supplied to the terminal 28. When the reproduction control pulse P _c is supplied to the other input end of the AND gate 27, the reproduction control pulse P _c is obtained at the output end of the AND gate 27 and supplied to the input end of the control pulse detection circuit 29. To be done. In the control pulse detection circuit 29, the high level signal S is _{generated based} on the reproduction control pulse P _c.
c is obtained and is supplied to the reset end of the timer 30.

Here, the timer 30 detects not only a non-recording portion such as the non-recording portion 13 shown in FIG. 2A but also a non-recording portion such as the non-recording portion 13 'shown in FIG. 2B. The settings are made to enable this. Therefore, the measurement time of the timer 30 is calculated by the control pulse recording unit 46.
The control pulse lacking section 48 following the above is located between the full-width erasing head 4 and the control head 7b on the magnetic tape, like the control pulse missing section in the non-recording section 13 'shown in FIG. 2B. When the size of the control pulse is small, that is, the part corresponding to the travel path length, it is set with the time required for the cutout part 48 of the small control pulse to pass through the control head 7b. It For example, in the example shown in FIG. 2B described above, the length of the small-scale control pulse lacking portion 48 is T, and the short-scale control pulse lacking part 48 is missing. The removal unit 48 is the control head 7b
If the time required to pass through is t, the measurement time of the timer 30 is set to t.

In the as described above, when a high level signal S _c which is obtained by the control pulse detection circuit 29 is supplied to the reset terminal of the timer 30, the timer 30 is reset. Then, as shown in FIG. 4A, at the point C ₂ where the control head 7b records the last control pulse 47 of the first control pulse recording unit 46.
Since the control pulse lacking portion 48 continues to be located at the point C ₃ after the control pulse 47 is read at the position C, the reproduction control pulse P _c cannot be obtained. The signal S _c from the control pulse detection circuit 29 is set to low level and supplied to the timer 30. Therefore, the control head 7
From when b is located at point C ₂ until it is located at point C ₃ ,
The high-level signal _Sc is not supplied to the reset end of the timer 30 for the time t. This makes timer 3
0 ends the time measurement without being reset. When this time measurement is completed, the timer 30
The signal S ₈ obtained from the output end of the magnetic tape is changed from the low level to the high level, which corresponds to the non-recorded portion of the magnetic tape. This high level signal S ₈ is applied to the AND gate 3
1 is supplied to one input terminal. The low level signal S ₆ from the exclusive OR gate 24 is inverted by the inverter 34 and supplied to the other input terminal of the AND gate 31 as a high level signal S ₆ . This makes AND gate 3
A high level signal S ₉ is obtained at the output of 1. This high level signal S ₉ is supplied to the reset end of the counter 32.

The counter 32 starts counting pulses after the high-level signal S ₉ is supplied to its reset terminal, and the signal S ₂ obtained at its output terminal is normally at a high level and has a predetermined number of pulses. When it is counted, it is changed to a low level.

In this way, the control head 7b passes through the control pulse lacking portion 48 and the second portion corresponding to the portion where the new inclined track 10 shown in FIG. 2B is formed.
Point C which is the end of the control pulse recording section 49 of
_At position ₄ , the reproduction control pulse P _c is again obtained and supplied to the terminal 28, and then supplied from the output end of the AND gate 27 to the input end of the counter 32. Then, the counter 32 counts the reproduction control pulse P _c . Here, the point C ₄ to first play control pulse P _c after the point C ₂ is obtained, with an end portion of the second control pulse recording unit 49, since it is the beginning portion of the cut-off parts 48 of the control pulse , This point C
_Although it is conceivable to complete the blank search operation in step ₄ , in this example, in consideration of the operation delay at the start of the recording operation of the video tape recorder, in this example, the end portion of the second control pulse recording section 49 is terminated. From, for example, 10
The blank search operation is completed at the position where the pulse is obtained, and accordingly, when the counter 32 counts 10 pulses, the signal S ₂ obtained at the output end becomes low level.

When the low-level signal S ₂ obtained when the counter 32 counts 10 pulses is supplied from its output end to the other input end of the AND gate 22, the high level signal sent from the output end of the AND gate 22 is sent. Signal S ₃ is changed to a low level signal S ₃ and is supplied to the first output terminal. This causes the tape drive to stop the magnetic tape. Also, the low-level signal S ₃ from the AND gate 22
Is also supplied to the input terminal of the blank search command unit 26,
As a result, the blank search operation command is released and the blank search operation is completed. That is, blank search operation is caused to complete when positioned at the end point C ₅ to control head 7b is shown in Figure 4 A.

In the case of the embodiment shown in FIG. 4B, the control head 7b is located at the starting point C ₆ on the cutout portion of the control pulse corresponding to the non-recording portion 13 shown in FIG. 2A. The blank search operation is started from this position. And while reaching the control head 7b is the point C ₇ when the time t from the start has elapsed, since during reproduction control pulse P _c can not be obtained, the timer 30 corresponding to the unrecorded portion of the magnetic tape, a high level signal S ₉ is supplied to the reset end of the counter 32, and the counter 32 is a magnetic tape capable of counting pulses. Then, as in the case of the mode shown in FIG. 4A, the counter 3
The blank search operation is completed at the end point C ₈ where 10 pulses are counted in 2.

Next, the aspect of the blank search shown in FIG. 4C is
This is a case where a blank search operation is performed in a so-called fast-forwarding state in which the magnetic tape is rapidly run in the forward direction.

First, in order to obtain the fast-forward state, the high-level signal S ₁ is sent from the AND gate 22 from one output end of the travel command unit 21.
Is supplied to one of the input terminals. The other input terminal of the AND gate 22 is supplied with a signal S ₂ which normally has a high level from the output terminal of the counter 32, whereby a high level signal S ₃ is obtained at the output terminal of the AND gate 22. When this high-level signal S ₃ is supplied to the first output terminal 23, the tape drive unit is brought into a state of traveling.

On the other hand, the high-level signal S ₄ is supplied from the other output end of the travel command unit 21 to one input end of the exclusive OR gate 24. At the other input terminal of the exclusive OR gate 24,
A signal S _5, which normally takes a low level, is supplied from the output terminal of the AND gate 33, whereby the exclusive OR gate 2
A high-level signal S ₆ is obtained at the output terminal of 4 and is supplied to the second output terminal 25. As a result, the drive unit for the magnetic tape causes the magnetic tape to run in the fast-forwarding state.

When the blank search operation is performed in such a state,
A high-level signal S ₇ is supplied from the output terminal of the blank search command section 26 to one input terminal of the AND gate 27.
Then, as shown in FIG. 4C, the control head 7b is in the control pulse recording portion in the control track of the portion corresponding to the portion in which the inclined track 10 shown in FIGS. 2A and 2B is formed, The blank search operation is started from the state of being located at the starting point C ₉ and reaches the point C ₁₀ which is the end portion of the control pulse recording section. Then, after passing the point C ₁₀ , the playback control pulse P _c cannot be obtained, and when reaching the point C ₁₁ at which the time t has elapsed, the playback control pulse P _C during that time is reached.
Since is not obtained, it becomes a high level signal S ₈ is obtained at the output terminal of the timer 30 as described above, according to the non-recording portion of the magnetic tape of the high level, while the signal S ₈ is the AND gate 33 Is supplied to the input end of. Since the high level signal S ₆ is supplied to the other input terminal of the AND gate 33 from the output terminal of the exclusive OR gate 24 at that time, the high level signal S ₈ is supplied to the other input terminal of the AND gate 33. The signal S ₅ from the output end is changed from low level to high level. This high level signal S ₅ is supplied to the other input terminal of the exclusive OR gate 24. At this time, since the high level signal S ₄ is supplied to the one input end of the exclusive OR gate 24 from the other output end of the travel command unit 21, the high level signal S ₅ is supplied. Signal S ₆ from the output of exclusive OR gate 24
Is changed from a high level to a low level and is supplied to the second output terminal 25. As a result, the drive unit for the magnetic tape, which has been causing the magnetic tape to run in the fast-feeding state according to the high-level signal S ₆ , is now in accordance with the low-level signal S ₆ . The magnetic tape is made to run in a rewound state by reversing the running direction.

Then, the low level signal S ₆ from the output terminal of the exclusive OR gate 24 is inverted by the inverter 34 and becomes the high level signal S ₆ and is supplied to the other input terminal of the AND gate 31. At the other input end of the AND gate 31,
Since the high level signal S ₈ from the timer 30 is supplied, the high level signal S ₉ is obtained from the output end of the AND gate 31 and supplied to the reset end of the counter 32. The subsequent operation is the same as the blank search operation in the rewinding state described above, and the blank search operation is completed at the end point C ₁₂ where 10 pulses are counted by the counter 32.

Effect of the Invention As described above, according to the magnetic recording / reproducing apparatus of the present invention, it is possible to automatically perform a so-called blank search for finding the beginning of a non-recorded portion in a magnetic tape, and It is extremely easy to carry out the continuous recording of the recording already made on the tape. Further, the blank search operation can be performed by any of the fast-forwarding and rewinding operations, and the end position of the blank search can be determined by counting the control pulse at the end of the already recorded portion. Since it can be determined as appropriate, extremely excellent operability can be obtained and a quick and accurate blank search can be performed.

[Brief description of drawings]

FIG. 1 is a diagram used for explaining a traveling path of a magnetic tape in an example of a magnetic recording / reproducing apparatus according to the present invention, and FIG. 2 is a diagram used for explaining a recording mode of the magnetic tape. Three
FIG. 4 is a block connection diagram showing an essential part of an example of a magnetic recording / reproducing apparatus according to the present invention, and FIG. 4 is a diagram used for explaining the operation of the essential part shown in FIG. In the figure, 7b is a control head, 21 is a travel command section,
23 and 25 are first and second connected to the tape driving unit.
Is a blank search command section, 28 is a terminal to which a reproduction control pulse is supplied, 29 is a control pulse detection circuit, 30 is a timer, and 32 is a counter.

Claims (1)

[Scope of utility model registration request] 1. A detection unit for detecting a reproduction control pulse obtained by a reproduction head for reading the control pulse from a magnetic tape on which a control pulse is recorded corresponding to an inclined track, and the reproduction control in the detection unit. A portion of the magnetic tape in which no pulse is detected corresponds to the length of the traveling path between the reproducing head and the full width erasing head provided for erasing the signal recorded on the magnetic tape. When a time required to pass through the magnetic tape is detected and a detection output is generated according to the non-recorded portion of the magnetic tape, and after the detection output from the time detection portion is obtained, A tape running control unit that makes the magnetic tape run in a direction opposite to the normal playback direction, either continuously or by reversing the running direction. , A counter that is reset according to the detection output from the time detection unit, and after the detection output is obtained, the magnetic head is driven in the direction opposite to the reproduction forward direction by the reproduction head. And a tape drive unit for stopping the running of the magnetic tape when a predetermined number of the reproduction control pulses are counted by the counter. Magnetic recording / reproducing device.