JPS63117388A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To rapidly complete an unnecessary part at the either time of recording and reproducing a video signal and an audio signal by travelling a magnetic tape at high speed until the index signal of a first frequency is detected when the index signal of a second frequency is detected at the time of ordinary reproducing. CONSTITUTION:A position detection circuit 27 for detecting the position of a margin part, an index signal generating circuit 23 for generating the index signal of a prescribed frequency recorded in the margin part (c), a first switch for switching the index signal to the first and the second frequencies, a first index signal detection circuit 24 for detecting the index signal of the first frequency, a second index signal detection circuit for detecting the index signal of the second frequency, a second switch for substantially allowing the detection operation of the index signal of the second frequency and a control means 19 for travelling the magnetic tape at high speed until the index signal of the first frequency is detected when the index signal of the second frequency is detected at the time of the ordinary reproduction are provided. Thereby, a skip operation can be easily and automatically executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing apparatus for recording and reproducing information using a rotating magnetic head such as an 8 mm video tape recorder.

[Summary of the invention]

In the present invention, during normal reproduction, when the index signal of the second frequency is detected, the magnetic tape is run at high speed until the index signal of the first frequency is detected.

[Conventional technology]

When recording a TV program and playing it back later, there are times when you want to skip unnecessary parts such as commercials and redundant and boring parts.

In such a case, when the unnecessary part starts, operate the switch to start the picture search, and when the unnecessary part ends, operate the switch again to end the picture search, or
Alternatively, the switch can be continued to be operated during the unnecessary portion, and when the unnecessary portion is finished, the switch can be released to return to normal playback. In this way, the magnetic tape is run at high speed during the picture search, making it possible to quickly finish unnecessary portions.

[Problem that the invention seeks to solve]

However, when playing back a magnetic tape many times, it is troublesome to operate the switch each time. Therefore, for example, an index signal is recorded at the end of the unnecessary part (the beginning of the useful part), and when the unnecessary part starts, a switch is operated to search for the next index signal, and the next index signal is recorded. It is conceivable to have normal playback automatically start from the position where it is. This makes the operation easier, but it is still cumbersome because the user has to recognize the starting point of the unnecessary portion each time.

It is possible to cut unnecessary parts and edit by dubbing, but this requires at least two magnetic recording and reproducing devices, and the editing process is complex and takes a long time, so general users do not tend to do this. Not executed. Furthermore, there is a drawback that the image quality deteriorates when editing work is performed.

Furthermore, 8mm video tape recorders can record and play back video signals and record and play back PCM audio signals on multi-tracks, and it is possible to perform similar operations in both cases. desired.

[Means for solving problems]

In the present invention, a first portion and a second portion are formed on a track inclined with respect to the longitudinal direction of a magnetic tape by a rotating magnetic head, and at least the first portion further includes a portion a on which a clock signal is recorded; The part where data such as PCM audio signals is recorded is divided into a margin part C for after-recording and an overlap part d where the signal of the immediately previous field is continuously recorded. A magnetic recording and reproducing device that records and reproduces predetermined information in a second portion includes a position detection circuit that detects the position of the margin portion, and an index signal generation circuit that generates an index signal of a predetermined frequency to be recorded in the margin portion C. , a first switch that switches the index signal between the first and second frequencies, a first index signal detection circuit that detects the index signal of the first frequency, and a second switch that detects the index signal of the second frequency. a second switch that substantially allows the detection operation of the index signal of the second frequency;
and control means for causing the magnetic tape to run at high speed until the index signal of the first frequency is detected when the index signal of the first frequency is detected.

[Effect]

An index signal of the second frequency is recorded in a margin section corresponding to the beginning of unnecessary information, and an index signal of the first frequency is recorded in a margin section corresponding to the beginning of necessary information. When the second switch is operated and the detection of the index signal of the second frequency is substantially permitted 1. When the index signal of the second frequency is detected during normal playback, the control means causes the magnetic tape to move at high speed. let it run,
The index signal of the first frequency is searched.

〔Example〕

FIG. 1 shows a block diagram when the magnetic recording/reproducing apparatus of the present invention is applied to an 8 mm video tape recorder. In the figure, reference numeral 11 denotes a rotating drum, into which a rotating magnetic head (not shown) for recording or reproducing is mounted.

12 is a motor that rotates the rotating drum 11. 13
and 14 are a frequency generator and a pulse generator, respectively, which output signals of a frequency and phase corresponding to the rotation of the rotating drum 11, and their outputs are supplied to a servo circuit 15.

The servo circuit 15 outputs a rotation control signal to the motor 12 and also outputs a head switching signal (H3WP signal) for switching a plurality of rotating magnetic heads. This head switching signal is transmitted by a variable delay circuit 1 provided as necessary.
6 to the pulse generation circuit 17. The pulse generating circuit 17 outputs pulses that control the on/off of the switches 18.21. Reference numeral 19 denotes a control means such as a microcomputer, which controls turning on and off of the switch 20 as well as various circuits and means. 2
A recording amplifier 2 amplifies a signal supplied to a rotating magnetic head for recording or reproducing information. 23 is an index signal generation circuit which outputs an index signal of a predetermined frequency to the recording amplifier 22 via a switch 20.18. Further, reference numeral 24 denotes an index signal detection circuit consisting essentially of two detection circuits, which detects an index signal from the reproduction signal of the preamplifier 25. 26 is an oscillation circuit that generates an erase signal of a predetermined frequency. A position detection circuit 27 detects a predetermined position from the reproduction signal supplied from the rotary head. 28 is a switch that is operated when manually recording the index signal, 29 is a switch that is operated when changing the frequency of the index signal to be recorded, and 30 is a switch that is operated when performing a skip operation.

The operation thereof will be explained with reference to FIGS. 2 to 5. The recording amplifier 22 receives signals to be recorded, such as video signals, PCM audio signals, FM audio signals, and tracking pilot signals, through a video circuit (not shown),
Each signal is supplied from the PCM circuit, FM audio circuit, tracking circuit, etc.

These signals are recorded on the magnetic tape by a rotating magnetic head. During this time, the servo circuit 15 compares the signals from the frequency generator 13 and the pulse generator 14 with a reference signal, and controls the rotation of the motor 12 in response to the error signal. During reproduction, the reproduction signal from the rotating magnetic head is amplified by the preamplifier 25 and supplied to the video circuit, PCM circuit, FM audio circuit, tracking circuit, etc.

FIG. 3 shows how signals are recorded on the magnetic tape in this manner. That is, tracks 2 are formed on the magnetic tape 1, which are inclined with respect to its longitudinal direction. For convenience, the track 2 includes a first part corresponding to a winding angle of about 36 degrees of the magnetic tape 1 with respect to the rotating drum 11, and a first part corresponding to a winding angle of about 18 degrees.
a second part corresponding to the fifth, and the former has a PC
M audio signal and tracking pilot signal (T
PS signal), and in the latter, an FM video signal, an FM audio signal, and a tracking pilot signal can be multiplexed and recorded. The azimuth angle of the corresponding rotating magnetic head is inclined by about 10 degrees in the positive direction on one side of the adjacent tracks 2 and in the negative direction on the other side, so that crosstalk from the adjacent tracks is reduced. It has become. The width R is near one edge 3.
An audio track 4 is formed, and if necessary, normal analog audio signals can be recorded by a fixed head. A cue track having a width C is formed near the other edge 3, and a cue signal is recorded by a fixed head as necessary.

5 and 7 are guard tracks provided between the information recording track and the control signal recording track.

appear. That is, the first part further includes a part a where a clock signal is recorded, a part where data such as a PCM audio signal is recorded, a margin part C for after-recording, and a video signal of the immediately previous field. The video overlap portion d can be divided into a video overlap portion d and a video overlap portion d recorded. The end position of the portion d is the switching position of the rotary magnetic head, and the vertical synchronizing signal is located at a position separated by a distance e from there.

The length of each of these parts is, for example, 525 lines and 60 fields as in the case of the NTSC system, and 1
For example, 625 lines as in the PAL system,
In the 5o field system, the settings are as shown in the table.

FIG. 5 shows a case where a plurality of parts corresponding to the first part are formed in the part of the cylinder 2 (in the case of multi-track) (the part d can be considered to be included in the second part, but
For convenience, it will be included in the first part). In other words, the length of the first part is an integral multiple of approximately 5 times the length of the second part, and the part corresponding to the first part is 5 times the length of the second part.
For example, a PCM audio signal, for example, is recorded in each of six parts in total, consisting of parts a to d.

Next, the recording and reproducing operation of the index signal will be explained. In the present invention, the index signal is recorded in the margin portion C of the first or second portion of the track 2.

Part C is 3. for NTSC system. It has a length of OH (3.6H in the case of PAL system). The servo circuit 15 obtains a predetermined delay time as necessary by counting, for example, a predetermined clock pulse from the outputs of the frequency generator 13 and the pulse generator 14 corresponding to the rotation of the rotating drum 11, and switches the head. A signal is output (FIG. 2(a)), and this signal is sent to the pulse generation circuit 17 via the variable delay circuit 16.
(The variable delay circuit 16 is not necessarily required if the track configuration is as shown in FIGS. 3 and 4). The pulse generating circuit 17 generates a signal when a predetermined time has elapsed since the generation of the head switching signal (for example, when 256.7 (262,5-3,8-3,0+1°0)H has elapsed in the case of the NTSC system), that is, when part C At the timing when the recording unit 9 of the index signal arrives (FIG. 2(b)), a recording pulse of a predetermined width (for example, 1°5H) is output, and the switch 18 is turned on during this time (FIG. 2(Q)). solid line). When the index recording operation is performed manually or automatically by operating the switch 28, the control means 19 activates the pulse generation circuit 17 and also activates the pulse generation circuit 17 and controls the predetermined time required for reproducing and detecting the index signal. (For example, when the switch 28 is operated, 1
Since the switch 20 is turned on for 0 seconds, the index signal outputted by the index signal generation circuit 23 (see FIG.
d)) is connected to the recording amplifier 22 via the switches 20 and 18.
(Fig. 2(e)). Such operation takes a predetermined time (
10 seconds), a predetermined number of tracks 2 (the number required for reproducing and detecting the index signal) are formed in which the index signal is recorded in the portion (2).

In the case of a multi-track system in which, for example, a PCM audio signal is recorded on all of one track 2 as shown in FIG. variable delay circuit 16
is provided. Even in this case, the basic timing is the same as in the cases shown in Figures 3 and 4, so
There is no need to provide any special circuit other than the variable delay circuit 16, so even in the case of multi-track, the on-dex signal can be recorded at a predetermined position for each track.

When deletion of the index signal is commanded from an input means (not shown), the control means 19 activates the pulse generation circuit 17, as in the case described above, and at the timing when the recording part 9 of the index signal of part C arrives. , outputs an erase pulse of a predetermined width, and turns on the switch 21 during that time (
Figure 2 (c) broken line). The width of the erase pulse can be made equal to the width of the recording pulse, but in order to eliminate omissions and to prevent PCM data from being erased, the width of the erase pulse should be set at a distance of 0.5H from the end of the section. , it is preferable to extend the front and back of the recording pulse by 0.5H, for example, to make the length 2.5H so that the end thereof coincides with the end of portion C. When the erase command is issued, the control means 19 activates the 1 oscillation circuit 26 for a time equal to or slightly longer than the time for turning on the switch 20 (10 seconds). Therefore, an erasure signal (FIG. 2(f)) having a predetermined frequency higher than the index signal generated by the oscillation circuit 26 is generated.

It is recorded via the switch 21 (FIG. 2(g)).

In the above operation, the signals for controlling the switches 18 and 21 are generated using the head switching signal as a timing reference, so there is no error in the recording position on the magnetic tape during recording and playback, or when the signal is recorded on the first part. It is inevitable that the timing will shift due to a time axis error between the information recorded in the second part and the information recorded in the second part. Therefore, when the first part or the second part is played back, at least P and C are present there.
When an M audio signal is recorded, the position detecting circuit 27 decodes the demodulated signal of the PCM audio signal, for example, a synchronization signal indicating the start of data, an arbitrarily determined specific data block address, etc. The starting point of portion C or the ending point of portion C is detected using the signal as a timing reference (Fig. 2 (h)), and a signal indicating the recording position of the index signal is generated in synchronization with this detection signal. Therefore, in this case, the pulse generation circuit 17 receives the output of the position detection circuit 27 when a PCM audio signal is recorded, and the output of the variable delay circuit 16 when a PCM audio signal is not recorded. As a timing reference, a recording pulse and an erasing pulse are respectively generated to control the on/off of the switches 18 and 21.

In this manner, when the switch 28 is operated at a predetermined position, an index signal is recorded for 10 seconds from that position. By switching the switch 29, the frequency of the index signal to be recorded can be changed. Thus, for example, an index signal of the first frequency at the beginning of the music signal.

Furthermore, an index signal of the second frequency can be recorded at the beginning of each commercial or the like.

The index signal can be recorded not only in a recording mode for recording audio signals, but also in a playback mode for reproducing recorded audio signals. In the case of the reproduction mode (in the case of after-recording), the recording mode is switched when the rotary magnetic head is at a position corresponding to the margin portion C, and the reproduction mode is switched when the rotating magnetic head is at another position.

On the other hand, during a search, the magnetic tape 1 on which the index signal is recorded is fast-forwarded or rewound while being wound around the rotating drum 11. At this time, the index detection circuit 24
detects the index signal of the first frequency from the reproduction signal supplied from the one-rotation magnetic head via the preamplifier 25, and outputs the detection signal to the control means 19 when detected.

The control means 19 searches for a designated desired song (program) by counting the number of detection signals, etc., and when it is searched, controls the servo circuit 15 to cause the magnetic sheep 1 to run at a normal speed. Let it play. In order to detect the index signal, only the reproduced signal in the vicinity of the index signal recording area I of the portion C is gate-extracted, and is synchronized with the output of the position detection circuit 27 to sufficiently compensate for fluctuations during high-speed tape running. It is also possible to generate and use pulses with wider widths, including:

The above search operation is performed when the switch 30 is not turned on. In this case, the index signal detection circuit 24 does not output a detection signal even if it detects the index signal of the second frequency (or the detection signal is ignored), that is, in this case, the detection of the index signal of the frequency of the cylinder 2 is substantially prohibited.

When the switch 30 is turned on, a skip operation is executed.

That is, when the switch 3o is turned on, the index signal detection circuit 24 is allowed to detect not only the index signal of the first frequency but also the index signal of the second frequency. When the index signal of the second frequency is detected during normal reproduction, the control means 19 controls the servo circuit 15 to cause the magnetic tape 1 to run at high speed in the forward direction. The speed at this time may be, for example, the speed at which a picture search is performed to find a desired screen while looking at the playback screen (for example, 9 times the speed during normal recording and playback), or the speed at an even faster so-called fast forward (FF). can. The amount control means 19 also mutes the audio or video output.

When the index signal detection circuit 24 detects the index signal of the first frequency during high-speed running, the control means 19 controls the servo circuit 15 to stop the magnetic tape 1, and if there is an overrun, etc., the magnetic tape 1 is stopped as necessary. After rewinding the tape 1 to find the beginning of the index signal of the first frequency, normal playback is performed from there.

In this way, signal reproduction is skipped from the index signal recording position of the second frequency to the index signal recording position of the first frequency.

Incidentally, it is desirable that the index signal has a frequency as low as possible in order to reduce the influence of the head azimuth and to facilitate detection even during fast forwarding or rewinding. The standard specifies that the pilot signal f is recorded. This pilot signal f is used to control the height of a plurality of rotating magnetic heads during recording when a piezoelectric element or the like is used in the holding portion of the rotating magnetic head for tracking control. The index signal is then higher than 230 kHz.

It is desirable to have a signal with a frequency that can be sufficiently separated in frequency from the pilot signal f, and also from the low frequency conversion color signal of approximately 740 kl (z±500 kHz).
For example, if the frequency of the index signal is approximately 1.2 MHz, it will be frequency (FM) modulated by the audio signal,
It is also sufficiently separated from the frequency of 1.5 MHz of the FM audio carrier multiplexed on the second portion of the inclined track, and can be easily separated and detected. However, when the frequency of signals recorded on a magnetic tape is low, the erasing effect is reduced. If the index signal remains without being completely erased, erroneous operations will occur during retrieval. Therefore, it is preferable to select a higher frequency for the index signal than the FM audio carrier.

On the other hand, as mentioned above, the frequency of the index signal needs to be lower than the frequency of its cancellation signal. Therefore, for example, the first frequency is set to 1/2 of the PCM audio data transmission rate of 368fl (f* is the horizontal synchronizing signal frequency) (2.895MHz (=15 in the case of the NTSC system)).
734X368/2)).

The second frequency can be set to 1/3 of that frequency, 1.93 MHz (=15734×368/3) in the case of the CNTSC system. If you set the frequency like this, your PC
The first and second index signals can be generated by dividing the clock signal used for the M circuit, and the P
A part of the CM data detection circuit can be used for index signal detection, and the circuit can be simplified.

In addition, the index signal set in this way is about 3 MHz away from the carrier of the luminance signal on the lower side, and the level of its sideband component has decreased, so the detection level when detecting the index signal may be erroneously detected. This makes it possible to set the settings with sufficient margin to prevent such occurrences.

〔effect〕

As described above, the present invention uses a rotating magnetic head to form a first portion and a second portion on a track inclined with respect to the longitudinal direction of a magnetic tape.
At least the first part further includes a part a where a clock signal is recorded, a part where data such as a PCM audio signal is recorded, a margin part C for after-recording, and a part A where a clock signal is recorded. A position for detecting the position of a margin part in a magnetic recording and reproducing apparatus that divides a field into an overlap part d where a field signal is continuously recorded, and records and reproduces predetermined information in the first part or the second part. a detection circuit, an index signal generation circuit that generates an index signal of a predetermined frequency to be recorded in the margin section C, a first switch that switches the index signal to a first frequency and a second frequency, and an index signal of the first frequency. a first index signal detection circuit that detects the index signal;
a second index signal detection circuit that detects the index signal of the second frequency; a second switch that substantially allows the detection operation of the index signal of the second frequency; and one that detects the index signal of the second frequency during normal reproduction. Since the magnetic tape is provided with a control means for running the magnetic tape at high speed until the index signal of the first frequency is detected, when the magnetic tape is applied to an 8 mm video tape recorder, the video signal and the PCM audio signal can be PCM is used not only for recording and playback, but also as a multi-track system.
Even when recording and reproducing only audio signals, it is possible to easily and automatically perform the skip operation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the magnetic recording/reproducing apparatus of the present invention, and FIG.
The figure is a timing chart, FIG. 3 is a plan view of the 8 mm video tape, and FIGS. 4 and 5 are enlarged plan views of its tracks. 1... Magnetic tape 2... Track 3... Edge 4... Audio track 5.7... Guard track 6... Cue track 11... Rotating drum 12... Motor 3.3 ... Frequency generator 14 ... Pulse generator 15 ... Servo circuit 16 ... Variable delay circuit 18, 20, 21 ... Switch 19 ... Control means 22 ... Recording amplifier 23 ...・Index signal generation circuit 24...Index signal detection circuit 25...Preamplifier 26...Oscillation circuit 27...Position detection circuit 28.29,3゛O...Switch or more

Claims (1)

[Claims] Forming a first portion and a second portion on a track inclined with respect to the longitudinal direction of a magnetic tape by a rotating magnetic head,
At least the first part further includes a part a where a clock signal is recorded, a part b where data such as a PCM audio signal is recorded, a margin part c for after-recording, and the signal of the immediately previous field. In a magnetic recording and reproducing apparatus that records and reproduces predetermined information in the first part or the second part, the magnetic recording and reproducing apparatus is divided into an overlap part d and recorded in the first part or the second part. , an index signal generation circuit that generates an index signal of a predetermined frequency to be recorded in the margin section c, a first switch that switches the index signal between a first frequency and a second frequency, and an index signal of the first frequency. The first step is to detect
an index signal detection circuit, a second index signal detection circuit that detects the index signal of the second frequency, and a second switch that substantially allows the detection operation of the index signal of the second frequency; During normal playback, the second
1. A magnetic recording and reproducing apparatus comprising: control means for causing the magnetic tape to run at high speed until the index signal of the first frequency is detected when the index signal of the first frequency is detected.