JP2639976B2 - Magnetic recording / reproducing device - Google Patents

Description

The present invention relates to a magnetic recording / reproducing apparatus.

(B) Conventional technology A technology for recording video signals derived from a plurality of video cameras in a single video tape recorder (VTR), or a technology for performing long-term recording by performing intermittent recording. There are many different things.

For example, Japanese Patent Laid-Open Publication No. Sho 60-195780 (G11B 20/10) discloses that several frames of intermittently extracted video signals are
By storing it once in memory and recording the contents of several frames stored on a magnetic tape continuously,
A technique has been disclosed that, when intermittent recording is performed at a prescribed value of the magnetic tape feed speed, the time interval of intermittent recording can be set short.

Also, JP-A-63-13480 (H04N 5/782)
A video signal of one or a plurality of fields is sequentially recorded together with its identification signal, and at the time of reproduction, the identification signal is detected, and a video signal unit in which the same identification signal is recorded together is extracted to obtain a reproduced image on a monitor. With this configuration, for example, even when video signals from a plurality of video cameras are recorded in a time-division manner in track units, it is possible to extract and reproduce only information taken by the same video camera based on the identification signal. The technology that enables this is shown.

(C) Problems to be Solved by the Invention However, in any of the conventional techniques, since one field of the standard television signal is recorded on one track on the magnetic tape, it takes a long time using one magnetic tape. When recording is performed, the time interval of intermittent recording becomes longer, and when used for monitoring or the like, there arises a problem that the time during which no image is captured becomes longer.

An object of the present invention is to enable recording for a longer time at the same amount of magnetic tape used and the same time interval of intermittent recording as before. Also, when recording video signals derived from a plurality of video cameras,
The purpose is to enable long-term recording.

(D) Means for Solving the Problems The present invention includes a memory area including a plurality of divided areas, and in the memory area, a digital signal obtained by A / D converting a signal for one field of a standard television signal is converted. Storable storage means, first conversion means for converting a standard television signal supplied to a video input terminal into a digital signal, and a digital signal corresponding to one field of the standard television signal derived from the first conversion means Compression writing means for sequentially compressing the divided areas in the horizontal and vertical directions at the same ratio, writing means for reading digital signals stored in the memory area, and reading means for reading digital signals stored in the memory area. The signal to one of the standard television signals
Second conversion means for converting the signal into a signal for a field;
Intermittent recording means for intermittently recording a signal derived from the conversion means on a magnetic tape.

The video camera further includes a plurality of video cameras and a selection unit for selectively supplying a standard television signal derived from each of the video cameras to the video input terminal.

Further, the correspondence between each video camera and each divided area is always constant.

(E) Function Since the present invention is configured as described above, a plurality of fields of the standard television signal are recorded on one track of the magnetic tape.

(F) Example An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of the first embodiment. In the figure, (1) is a video input terminal, and a video camera (2)
A standard television signal derived from the above is supplied. The standard television signal in this embodiment is an NTSC signal. Data such as date and time is added to the standard television signal by the on-screen circuit (3). (4) An A / D conversion circuit (first type) for converting an input standard television signal into a digital signal
Conversion means). (5) is a storage circuit (storage means) having a memory area composed of a plurality of divided areas. In the memory area, a digital signal obtained by A / D conversion of a signal for one field of a standard television signal can be stored. In this embodiment, the number of divided areas is four.
Individual. FIG. 3 is a diagram schematically showing a memory area (20), where (21), (22), (23), and (24) are divided areas.

(6) a synchronization signal detection circuit for detecting a vertical synchronization signal of a standard television signal supplied to the video input terminal (1);
(7) is an RF switch pulse forming circuit that forms an RF switch pulse from the vertical synchronization signal. (8) is a timing signal forming circuit that forms a WRITE signal and a REC signal based on an RF switch pulse. Upon receiving the WRITE signal, the compression writing circuit (compression writing means) (9) writes one field of the digital signal derived from the A / D converter (4) into the divided area of the memory. At this time, the compression writing circuit (9) compresses the digital signal for one field in both the horizontal direction and the vertical direction to perform writing, and the divided area to be written is
It changes cyclically each time a WRITE signal occurs.

As described above, four divided areas (21) (22) (23)
Since the digital signal corresponding to one field of the standard television signal can be stored in the memory area (20) composed of (24), the digital signal corresponding to one field of the standard television signal is stored in the horizontal direction. When the data is compressed to 1/2 in both the vertical and vertical directions, it is possible to store digital signals corresponding to one field in one divided area. Therefore, in the memory area (20), digital signals for four fields are stored. Upon receiving the REC signal, the readout circuit (reading means) (10) reads out the digital signal for four fields stored in the memory area (20) as a signal for one field of the standard television signal. The read signal is
In a D / A conversion circuit (second conversion means) (11), the signal is converted into an analog signal, and the recording signal processing circuit (intermittent recording means)
(12) It is recorded on a magnetic tape via a recording amplifier (intermittent recording means) (13) and the like. At this time, recording on the magnetic tape is performed intermittently.

During reproduction, the second switch (18) is switched so as to select the reproduction signal processing circuit (15) side, and the signal recorded on the magnetic tape is reproduced by the reproduction amplifier (14) and the reproduction signal processing circuit (15). ) And the like, and reproduced as a standard television signal, and an image is displayed on the monitor (16). When the first switch (17) is switched to select the on-screen circuit (3), data such as date and time is included in the standard television signal supplied to the video input terminal (1). The added signal is recorded as it is.

FIG. 2 is a diagram showing the timing of the WRITE signal, REC signal, and the like.

(A) shows a standard television signal supplied to the video input terminal, and each numeral is a number assigned to each field. (D) is a WRITE signal, and the first WRI
In synchronization with the TE signal, the compression writing circuit (9) writes the digital signal corresponding to the sixth field in the division area (21), and in the next WRITE signal, the division area (22)
Then, a digital signal corresponding to the twelfth field is written. (E) shows a change in the contents of the memory area (20), and the numbers are numbers indicating the fields of the written digital signal. Writing is performed every six fields, and when writing is performed in the divided area (23) and the divided area (24), an REC signal shown in (f) is generated.
The contents stored in the memory (20) are recorded on a magnetic tape. (G) is a recording pattern on a magnetic tape, in which digital signals for four fields are recorded on one track on the magnetic tape. In this case, intermittent recording is performed every 24 fields.

(B) and (c) show the REC signal and the recording pattern on the magnetic tape in the conventional intermittent recording. (B)
Is an REC signal when recording six times longer than normal recording is performed by intermittent recording. The period is not constant because azimuth recording is performed by alternately using two-channel heads. This is because it is necessary to record even fields mutually.

A comparison between the conventional intermittent recording and the present embodiment shows that according to the present embodiment, it is possible to record four times as long with the same amount of tape used.

In this embodiment, when the cycle of the REC signal is set in the same manner as in the related art, the recording time is the same, but the time interval of the intermittent recording can be shortened by setting the cycle of the WRITE signal short.

Next, a second embodiment will be described. FIG.
FIG. 3 is a block diagram of the embodiment, in which the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the present embodiment, one field of each standard television signal derived from four video cameras is combined and recorded on one track on the magnetic tape 1.

In the figure, (37) is a camera selection signal forming circuit, (3)
6) is a selection circuit, which is a camera selection signal forming circuit (3
7) and the selection circuit (36) constitute a selection means. The four video cameras (31) (32) (33) (34)
External synchronization is achieved by a synchronization signal derived from a synchronization signal forming circuit (35), and a standard television signal derived from each video camera is supplied to a selection circuit (36). The timing signal forming circuit (37) is a synchronous signal forming circuit (35)
The yellow signal is input to form a REF signal and a REC signal. The REF signal is supplied to a writing circuit (39) and a camera selection signal forming circuit (37). The camera selection signal forming circuit (37) forms a camera selection signal based on the REF signal, and derives it to the selection circuit (36). The camera selection signal is a signal that is switched in synchronization with the field cycle, and the selection circuit (36) controls each video camera (31) (32) (33) (34)
The supplied standard television signal is cyclically selected in the field cycle, and is derived to the video input terminal (1). The camera selection circuit (36) supplies an index signal to the writing control circuit (39). The index signal is
This signal is issued when the selection of the video cameras (31), (32), (33), and (34) is repeated. Compression writing circuit (39)
The video input terminal (1) is synchronized with the switching of the REF signal from H level to L level and from L level to H level.
A / D conversion of a standard television signal derived in (1) is performed, and the digital signal is compressed and written into the divided areas (21) (22) (23) (24). In this embodiment, each video camera (3
1) (32) (33) (34) and each divided area (21) (22) (2
3) and (24) always correspond to each other, and this correspondence is controlled by the index signal.

When the timing signal forming circuit (38) derives the REC signal, the readout circuit (10) converts the compressed digital signal for four fields stored in the memory (20) into a signal for one field of the standard television signal. The read signal is converted into an analog signal, and data such as date and time is added by an on-screen circuit (3), and then recorded on a magnetic tape. The REC signal is stored in the memory (20)
It is also used as a write prohibition signal to the memory, and when the REC signal is generated, writing to the memory is not performed.

FIG. 5 is a diagram showing the timing of the REF signal, the REC signal, and the like.

In the figure, (a) is a REF signal, (b) is an inverted signal of the REF signal, and (c) is a frequency-divided signal obtained by dividing the signal of (b). The inverted signal (b) and the frequency-divided signal (c) constitute a 2-bit camera selection signal. (D) shows each video camera (31) (3) leading to the video input terminal (1).
2) Indicates the standard television signal in field units from (33) and (34).
It means that it corresponds to (34). (F) is an index signal which becomes H level when both the inverted signal (6) and the frequency-divided signal (c) are H level, and each video camera (31) (32) (33) (34); Division area (21) (22)
(23) and (24) are always used to make the correspondence constant. That is, after the fall of the index signal, the divided area to which writing is performed first is always the divided area (21). Division area (21) (22) (23)
The digital signal is written to (24) by the REF signal (a).
In synchronization with the fall from H level to L level and the rise from L level to H level. (E)
This is an REC signal, and the contents of the memory area (20) are recorded on the magnetic tape in synchronization with the REC signal (e). The REC signal (e) is generated in a cycle corresponding to four fields of the standard television signal, and therefore, intermittent recording on the magnetic tape is also performed every four fields. (G)
Indicates a change in the content of the memory area (20) recorded on the magnetic tape in synchronization with the REC signal (e).
When the REC signal (e) is generated, the contents of the memory area (20) cannot be rewritten. (I)
Indicates a recording pattern on a magnetic tape. According to the above configuration, one field of each of the standard television signals derived from the four cameras is combined and recorded on one track on the magnetic tape, so that each video camera (31) (32) is always reproduced. (33) The video shot by (34) is displayed at a fixed position on the screen of the monitor (16).
FIG. 6 shows a screen of the monitor (16) at the time of reproduction, and the images corresponding to the video cameras (31), (32), (33), and (34) are the positions (41), (42), and (43), respectively. Displayed in (44). In the figure, the superimposed numbers are
This is disabled by the on-screen circuit (3). Further, in this embodiment, since the reproduction from the magnetic tape is performed at the same cycle as the recording, it corresponds to each video camera (31) (32) (33) (34) reproduced on the monitor (16). Each video is a moving image that is updated at a quarter of the field frequency of the standard television signal.

In this embodiment, the video cameras (31), (32), (33)
Since the selection of (34), writing to the memory (20), and recording to the magnetic tape are all synchronized,
With a simple configuration, each video camera (31) (32) (33) (3
The video captured by 4) is synthesized.

In the second embodiment, the writing of the digital signal to the divided area is performed every other feed by setting the cycle of the REF signal to twice, changing the camera selection signal to a signal that is switched in synchronization with the frame cycle, or the like. The recording time can be extended by setting the cycle of the REF signal twice or the like.

The present invention is not limited to the above-described embodiment. For example, the number of divided areas in the memory area is set to 9
And one of the standard TV signals
It is also possible to compress the digital signal corresponding to the field amount into one-third in both the horizontal direction and the vertical direction and write the data in one divided area. In this case, signals derived from the nine cameras can be recorded on one track of the magnetic tape.

(G) Effects of the Invention As described above, according to the present invention, it is possible to record for a longer time with the same amount of magnetic tape used and the same time interval of intermittent recording as in the related art. Further, no special decompression means is required for reproduction. In addition, video signals derived from a plurality of video cameras are synthesized with a simple configuration, and writing to a magnetic tape is performed. In this case, recording can be performed for a longer time than before. , The effect is great.

[Brief description of the drawings]

FIG. 1 is a block diagram of the first embodiment, FIG. 2 is a diagram showing timing of each signal, FIG. 3 is a diagram schematically showing a memory area, and FIG. 4 is a diagram of the second embodiment. FIG. 5 is a block diagram showing the timing of each signal. FIG. 6 is a diagram showing an example of a reproduction screen of a monitor. (1) ... video input terminal, (4) ... A / D conversion circuit (first conversion means), (5) ... storage circuit (storage means),
(9) (39) ... compression writing circuit (compression writing means), (10) ... reading circuit (reading means), (1)
1) D / A conversion circuit (second conversion means), (20) ... memory area, (21) (22) (23) (24) ... divided area,
(31) (32) (33) (34) ... Video camera, (36) ...
... selection circuit (selection means), (37) ... camera selection signal formation circuit (selection means).

Claims (3)

(57) [Claims] A memory means comprising a memory area comprising a plurality of divided areas, in which memory a digital signal obtained by A / D converting a signal for one field of a standard television signal can be stored; First conversion means for converting a standard television signal supplied to a terminal into a digital signal; and a digital signal corresponding to one field of the standard television signal derived from the first conversion means, which is sequentially transferred to the divided area in the horizontal direction. Compression writing means for compressing and writing in the same ratio in the vertical direction; reading means for reading a digital signal stored in the memory area; and a digital signal read by the reading means for one field of a standard television signal. Second converting means for converting the signals into minute signals, and intermittently recording the signals derived from the second converting means on a magnetic tape. Magnetic recording and reproducing apparatus characterized by comprising: a recording unit. 2. The apparatus according to claim 1, further comprising a plurality of video cameras, and a selection unit for selectively supplying a standard television signal derived from each of said video cameras to said video input terminal. 3. The magnetic recording and reproducing device according to claim 1. 3. The magnetic recording / reproducing apparatus according to claim 2, wherein the correspondence between each video camera and each divided area is always constant.