JPS59158181A - Video tape recorder - Google Patents

Abstract

PURPOSE:To shorten the time of simultaneous recording of plural channels and to reproduce an optional video signal selectively by compressing different video signals of N channels to 1/N and recording them alternately. CONSTITUTION:When frequencies fR1 and fR2 of readout clocks are set twice as high as frequencies fW1 and fW2 of write clocks, video signals outputted from memories 7 and 8 are read out in 1/2 compressed states, so one field or one frame of signals of both channels A and B is recorded on one magnetic track. A composite video signal reproduced by a head HV is supplied through the 1st switching means 32 to a memory 33 and its contents are written. Therefore, when the 1st switching means 32 is changed over as shown by a broken line, reproduced video signals of both channels A and B are obtained at the same time, and when the 1st switching means 32 is changed over as shown by a solid line, the reproduction screen of the channel of A or B is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION This invention relates to a video tape recorder capable of simultaneously recording and reproducing video signals of two or more different channels.

BACKGROUND TECHNOLOGY AND □ PROBLEMS For example, to display the video content of two or more different channels on the same screen, for example, as shown in Figure 1, A-8 To display the video content of two channels at the same time, a circuit like the one shown in Figure 2 is required. is used.

This is picture-in-picture (P-i-n-P
) technology, which uses a pair of TV tuners (1) as shown in the figure.
(3) and (4) are video intermediate frequency amplification circuits, (5) and (6) are video detection circuits, and the detected video signals are stored in a memory, for example, the L field capacity. Write to 1 and 2nd memory (7), f8) -zM
Ru. Therefore, the detected video signal is supplied to the synchronization separation circuit fllJ, 1121, and the horizontal and vertical synchronization pulses H and V separated from each other are sent to the memory control circuit (
131. From this, the first and second memories (
Write and read clocks for 7) and (8) are formed. CKWICKw2 is the memory write clock, and CKR1.

CKR2 indicates a read clock.

To display the composite screen as shown in Figure 1, the read clock frequencies fR1 and fR2 are changed to the write clock frequencies fw1 and f.
It is selected to be twice as large as w2. First and second memory (7)
, (8) are sequentially and alternately read out every day H (H is a horizontal period), and then synthesized by a synthesizer (141), and the synthesized output is sent to the video output circuit a9. The signal is supplied to the cathode ray tube (le) through the video signal.As a result, images from two channels of video signals having different video contents as shown in FIG. 1 are simultaneously reproduced.

++71. fla is an audio reproduction circuit, and its output is supplied to a speaker S or an earphone EK via a switching circuit f+91. In this case, when the A channel audio signal is being supplied to the speaker S, the B channel audio signal is switched so that it can be heard through the earphone E.

Now, in order to display the video contents of two or more different channels on the same screen at the same time, a video tape recorder that records and plays back those video signals has a method of recording the video signals of multiple channels on separate tracks. is taken.

That is, as shown in Fig. 3, the video signals of the outer channels A and B are alternately KEN'd, and during playback, appropriate signal processing such as signal compression is performed to obtain a playback screen as shown in Fig. 1. There is.

Therefore, in such a video tape recorder, if the tape recording time is T, the maximum recording time that can be applied to each of the A and B channels is 1. 1. If video signals of different N channels are recorded and reproduced simultaneously, the recording time will be reduced by KK. Therefore, such a recording/reproducing method is not suitable for long-term recording.

Purpose of the Invention Therefore, the present invention aims to improve the recording time when recording a plurality of channels at the same time, and also makes it possible to reproduce any video signal by arbitrarily selecting the town output.

SUMMARY OF THE INVENTION Therefore, in this invention, N channels of different video signals are compressed into X and recorded alternately, so that the recording time for each channel's video signal matches the maximum recording time T of the tape. At the same time, one or more of the recorded video signals can be arbitrarily played back.

Embodiment Next, an example of a video tape recorder according to the present invention will be explained in detail with reference to FIG. 4 and subsequent figures.

FIG. 4 shows an example of a recording system (20A) of a video tape recorder according to the present invention, and FIG. 5 shows an example of its reproducing system (20B).

Also in this invention, since the P-in-P technology as shown in FIG. 2 is applied, a pair of tuners (1
) and (2) are provided, and a circuit system for processing each signal is provided. That is, as in FIG. 2, (3) and (4) are video intermediate frequency amplification circuits, (5) and (6) are video detection circuits, and (7) and (8) are video intermediate frequency amplifier circuits, each having a capacity of ] field. 1 and the second memory, and (111 and +
Reference numeral 121 denotes a synchronous separation circuit, in which the synchronously separated horizontal and vertical synchronous pulses H and V are sent to the memory control circuit (I3
1 to form write clocks CKWI and CKw2 synchronized with pulses H and V, and newly output clocks CKR1 and CKR2 that serve as a reference for the reproduction screen.

When recording video signals of two different channels A1B as shown in Figure 1, fRt (fR2) - 2f
w1 (2fw2) is selected and the time axis of the signal is compressed and read out. As shown in FIG. 6, the recording track pattern is shown in FIG. Video signals are combined. The output of the synthesizing circuit (I4) is supplied to the recording/reproducing head Hv via the video recording circuit.

In addition, a part of the output of the video intermediate frequency amplification circuits (3) and (4) is supplied to the respective audio reproduction circuits (1η, 0 (to)), and after the audio signals of the respective channels are reproduced, the outputs are sent to the respective recording circuits. ; 23), (Head for the corresponding audio channel) IA, ) (13) and is recorded in a portion as shown in FIG. 6 in the longitudinal direction of the tape.

In this way, if the same wave numbers fR1 and fR2 of the read clock are selected to be twice the write clock frequencies 1 and 1w2, respectively, the video signal output from the memory f71 (8) can be read out in a compressed state. Therefore, as shown in Figure 6, one magnetic track that records the video content of one field or one frame records signals for one field or one frame of both channels A and B. Become. Therefore, compared to the case shown in FIG. 3, the recording time can be doubled.

Therefore, video signals of 82 channels can be recorded simultaneously for a recording time equal to the maximum recording time T of the tape.

FIG. 5 shows an example of a reproduction path (20B), in which the composite video signal reproduced from the head HV is supplied to the video reproduction circuit i' (1), where it is reproduced and demodulated, and then the first It is supplied to the memory (331) through the switching means GZ' and its contents are impregnated. Also, the synchronization separation circuit (34
] is the side leg circuit of the memory +351 VC is supplied to the memory I
A clock having a write frequency f)V and a read frequency fR for the JC33+ is formed, as well as horizontal and vertical synchronization pulses H" and V" for the final output.

Therefore, if the first switching means 2 is switched as shown by the broken line, the reproduced video signals of both channels A and 13 will be superior at the same time, so that the reproduced images of both channels A and B will be reproduced as shown in Fig. 7. 4 Ru. Then, the first switching means (32 is switched as shown by the solid line)
-"fW' is selected, the video signal of either the A channel or the B channel is output, so either the playback screen as shown in Fig. 8 is displayed.The switch SW selects the A or B channel. This is for switching.

Depending on how the memo IJC33) is read, a screen as shown in FIG. 9 can be inserted. In this case A,
It is also an OT function to change the channel contents of B.

Note that (36) is a video amplifier and (37) is a mixer.

On the other hand, the audio signals of both channels A and B reproduced by the heads HA and HB are supplied to the audio reproduction circuits (17) and (181, respectively) via the preamplifier (1), and the reproduced audio signals are sent to the second 4 switching means (4υ~+43)
and selects an audio signal corresponding to the selected image content.

The second switching means (used to select the video signal of either channel A or B)
Interlocks with switch SW. At this time, audio No. 9 is supplied to both the speaker S and the earphone E.

The third switching means (421 is made of aluminum as shown in FIG.
When the video signal of any channel B is encountered, the third switching means (431) is provided with the hole so as not to supply the audio signal.Therefore, the first switching means C33 and the Then, when the video signals of both channels A and B are selected at the same time, a fourth switching means (43) switches the respective audio signals to the speaker S.
and earphone E.

These switching means can be operated from the outside.

In this way, by switching the first switching means (32) and appropriately selecting the frequencies of the read and write clocks for the memory (c), video contents in both channels A and B as shown in Figure 7 can be simultaneously displayed. It is also possible to selectively extract only the video content of either channel A or channel B and enlarge it for display, or as shown in Figure 9, the video content for channel A can be selectively extracted and displayed. Part of the screen KB
It would also be a good idea to easily obtain the technology to embed a video screen for the channel.

As described in detail, according to the structure of the present invention, even if video signals of 2 to 5 different channels are recorded simultaneously, the recording time is the same as the large recording time T of the tape. Because you can ride over it, it is convenient for recording long conversations. By performing an appropriate signal selection operation, it is possible to display the video content of a single channel, to display the video content of two different channels on the same screen, or to display the video content of two different channels on the same screen. It is also possible to easily insert a special image as shown in the figure.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing an example of a display screen, Figure 2 is a system diagram of an example of a television receiver used to explain the present invention,
FIG. 3 is an explanatory diagram of a record track pattern, FIG. 4 is a system diagram of a recording system showing an example of a video tape recorder according to the present invention, FIG. 5 is a system diagram showing an example of its playback system, and FIG. 1 is a diagram showing an example of a recording track pattern recorded by this video tape recorder, and FIGS. 7 to 9 are diagrams each showing an example of a display screen for explaining its operation. (7), (8) are memories, (''& is a memory control circuit, (
14] is a synthesis circuit, t3'5 is a memory, L'15) is a memory control circuit, rWl, fW2, fW' are write clock frequencies, and fRl, fR2, fR are read clock frequencies.

Claims (1)

[Claims] Compressing and synthesizing video signals of two or more different channels and recording the synthesized output, and after playing the synthesized output, performs appropriate signal processing to simultaneously reproduce the video contents of the single or plural video signals, video tape recorder.