JPH0722363B2 - Magnetic reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The following description will be given.

A Industrial Field B Outline of the Invention C Conventional Technology D Problems to be Solved by the Invention E Means for Solving Problems (FIG. 1) F Action G Example G ₁ First Example ( (Figs. 1 to 3) G ₂ Other Embodiments (Fig. 4) H Effects of Invention A Field of Industrial Application This invention relates to a magnetic recording apparatus.

B Outline of the Invention The present invention controls the address of the RAM that stores the data of a still image when the still image can be recorded in the PCM audio recording area in an 8 mm video or multi-channel PCM audio device. As a result, the still image can be reproduced as a correct screen even when the tape is running in the reverse direction.

C Conventional technology In 8 mm video, it is permitted to record / reproduce an audio signal on a magnetic tape in a PCM signal state as an optional function.

That is, as shown in FIG. 5, a magnetic track (2) is formed obliquely on the magnetic tape (1), and a section (2S) 1/6 from the beginning is used for audio signals.
The stereo audio signal for the field period is time-axis compressed and recorded as a PCM signal, and the remaining 5/6 of track (2)
One field of the video signal is recorded in the section (2V).

In this case, the PCM audio track (2S) and the video track (2V) are formed by two rotary magnetic heads having an angular interval of 180 ° with each other, but the track (2S) rotates the rotary head by 36 °. The length is equivalent to a corner, and the scanning start section (21) of the rotary head, the clock run-in recording section (22), the valid PCM signal (PCM data) recording section (23), and the bark margin section ( 24) and guard section (25) are allocated in order as shown in the figure. Also, the video track (2V) has a length corresponding to a rotation angle of 180 ° of the rotary head, and the track (2V) has a length corresponding to a rotation angle of 5 °, similarly to a general VTR. The rotary head end section (2E) is provided.

By the way, in the above-mentioned standard, when the track (2V) is divided into five equal parts in the length direction, the length of each divided section corresponds to 36 °, which is equal to the length of the track (2S).

Therefore, paying attention to such a point, a recording / reproducing apparatus dedicated to an audio signal has been considered. This is a multi-channel PC
It is called an M audio device or a multi-track PCM audio device, and its standard is as shown in Fig. 6.

That is, as shown in the figure, the track (2S) is set to the first section # 1, and the track (2V) is divided into five equal parts in the length direction to be set to the second to sixth sections # 2 to # 6. . Then, a PCM audio signal is recorded by using an arbitrary section among these sections # 1 to # 6 for each track (2). In addition, section # 1
A predetermined section from the latter half of the guard sections (25) of # 6 to # 6 is set as an index section (26), and is used for cueing or the like.

Then, according to such a standard, it is possible to record and reproduce an audio signal for 24 hours using the tape (1) capable of recording and reproducing a video signal and an audio signal for 4 hours.

However, it has been considered to further record and reproduce a still image in accordance with the standard for recording and reproducing an audio signal.

That is, as shown in FIG. 7, at the time of recording, the video signal of a still image is time-axis expanded so that one line thereof becomes, for example, one of the sections # 2, and therefore, one field of 263 still images is recorded. It is recorded in the section # 2 in order over the track (2).

Then, at the time of reproduction, the video signal for one line is reproduced from the section # 2 and written into the memory, and the video signal of the original still image is taken out even if the contents of the memory are repeatedly read. In this case, since 263 track section # 2 is used to record or reproduce 1 field still image, it is possible to record or reproduce 1 field still image per 4.4 seconds (263 tracks / 60 fields). become.

The same applies to the other sections # 1 and # 3 to # 6.

(Reference; Specification and Drawings of Japanese Patent Application No. 60-204991) D Problems to be Solved by the Invention By the way, in a multi-channel PCM audio machine, tapes (1) are used for sections # 2, # 4, and # 6. It is also permitted to record a voice signal while running the above) in the opposite direction. However, for this reason, data indicating the running direction of the tape (1) is added to the user's bit. By doing so, when the audio signal is recorded or reproduced up to the end of the tape (1), it is not necessary to rewind the tape (1) to the beginning, and therefore, the tape is slightly recorded during the inversion period of the tape (1). And, by only interrupting the playback, it is possible to record and play for 24 hours almost continuously.

Therefore, even when recording a still image on the tape (1), it is conceivable to record the sections # 2, # 4, and # 6 while running the tape (1) in the opposite direction.

However, if the tape (1) is run in the reverse direction to record a still image in this manner, it takes time to reproduce the still image during reproduction.

That is, for example, as shown in FIG. 8, one field of a still image is recorded in the positive direction (the running direction of the tape (2) is the positive direction) in the section # 1 from the point A to the point B, and the same track (2 It is assumed that another field of one still image is recorded in the opposite direction in section # 2). Therefore, section # 1
For point # 2, point A is the recording start point and point B is the recording end point, and for section # 2, point B is the recording start point and point A is the recording end point.

Then, when the rotary head is at the point A, the tape (2) is moved in the forward direction to immediately start the section # 1.
However, for section # 2, the tape (2) must be fed to point B and then in the reverse playback mode, which requires much time to play the still image. Similarly, when the rotary head is located at the point B, when the still image in the section # 1 is reproduced, the tape (2) must be sent from the point B to the point A before the reproduction in the section # 1. , After all, it takes time to reproduce.

The present invention is intended to solve such a problem.

E Means for Solving Problems Therefore, in the present invention, when a still image is reproduced, the running direction of the tape when the still image is recorded is determined, and the still image reproduced by this determination output is reproduced. The video signal of is controlled to control the address of the RAM to be accessed.

F action Even if the tape running direction at the time of recording does not match the tape running direction at the time of reproducing, the correct still image video signal is taken out from the RAM.

G Embodiment G ₁ First Embodiment In FIG. 1, (3A) and (3B) show rotary magnetic heads, which have different slit angles and have angular intervals of 180 °. ing. The heads (3A) and (3B) are rotated at the frame frequency, and the magnetic tape (2) is attached to the rotating peripheral surface.
Is driven diagonally at a predetermined speed over a range of over 221 °. However, as shown in FIG. 2A,
1/5 field period Δ at the end of even field period Tb
T and the following odd field period Ta, the head (3A) scans the section # 1 to # 6 of the track (2), and the end 1/5 field period ΔT of the odd field period Ta
Then, in the subsequent even field period Tb, the head (3B) scans the portion of sections # 1 to # 6 of the next track (2).

Further, (4) shows a forming circuit which forms various timing signals, and these timing signals are supplied to respective circuits as shown in the drawing (a part thereof is not shown).

Then, at the time of recording, the color video signal Sc is supplied to the A / D converter (22) through the input terminal (21) and is sampled at, for example, the frequency 3fc (fc is the color subcarrier frequency), and 8 bits per sample Digital signal Sd, and this signal Sd is supplied to the RAMs (23A) and (23B). A clock is supplied from the formation circuit (4) to the formation circuit (41) to form a write signal and an address signal for one field period every 263 field periods, and these signals are transferred to the RAM through the switch circuit (43).
It is supplied alternately to (23A) and (23B) every 263 field periods. Therefore, the signal Sd from the converter (22)
Are alternately written to the RAMs (23A) and (23B) by one field period every 263 field period, as shown in FIGS. 3A and 3B. In this case, this writing is performed at a speed of frequency 3fc, but the signal Sd to be written in the one field period is from the 1st line to the 263rd line (or the 2nd line).
Signal from line 63 to line 525), that is, a correct still image signal, and RAM (23
In A) and (23B), for example, one sample is sequentially written from the first address to the last address.

Further, a clock is supplied from the forming circuit (4) to the forming circuit (42) to form a read signal and an address signal having a repeating period of 263 field periods, and these signals are written through the switch circuit (43). RAMs (23A) and (23B) not supplied are alternately supplied every 263 field periods. Therefore, as shown in FIGS. 3A and 3B, the signal Sd is read from the RAMs (23A) and (23B) during the 263 field period in which this writing is not performed.
However, in this case, this reading is performed at a frequency of 4f _H (f _H is a horizontal frequency), and RAM (23A),
From the start address of (23B), one line of the signal Sd is read out in sequence for each sample for one field period. Therefore, if this read signal is the signal Se, this signal Se is a correct still image signal, and in the signal Se, the time axis is expanded and the sampling rate is equal to that of the PCM audio signal. . Also, it takes 1 of the original signal Sd over the 263 field period.
The field period will be read.

Then, the read still image signal Se is supplied to the additional circuit (24), and the formation circuit (4) supplies the header signal Ss indicating the start point of the signal Se to the additional circuit (24). As shown in FIG. 3C, the signal Se has a specific bit pattern for the first few fields (first few lines outside the effective screen when viewed from the signal Sd), for example, a signal of all "0". That is, the header of a specific bit pattern is added.

The still image signal Se to which the header is added is supplied to the encoder (25) in the same format as the PCM audio signal of the track (2S), and the user's bit indicates the running direction of the tape (1). Having the data, as shown in FIG. 2B, the heads (3A) and (3B)
It is encoded into the PCM signal Sp during the period of scanning the section # 1 of the track (2), and this signal Sp is recorded in the recording amplifier (2
6) and the switch circuit (5) through the head (3A),
In (3B), it is supplied alternately every period Ta and Tb. Therefore, on the tape (1), the video signal (PCM signal Sp) of the still image is recorded in the section # 1 one by one line sequentially over the 263 tracks in each field period.

However, at this time, the header is recorded by the signal Ss in the first several tracks of the 263 tracks.

In this manner, the still image signal Sp is recorded in the section # 1 at a rate of one field every 263 field period.

On the other hand, during reproduction, the signal Sp is reproduced every time the heads (3A) and (3B) scan the section # 1 of the track (2),
This signal Sp is transmitted to the switch circuit (5) and the reproduction amplifier (3
The signal Se is supplied to the decoder (32) through 1) and the signal Se is decoded. The signal Se is supplied to the RAMs (23A) and (23B) as well as to the detection circuit (44) and the header signal.
Ss is detected, and the detected signal Ss is formed by the forming circuit (41).
Is supplied to.

Then, in the forming circuit (41), RAM (23A), (23
B) write signal and address signal are formed,
During reproduction, when the signal Ss is supplied to the forming circuit (41),
From the time of this signal Ss, as shown in FIGS. 3D and 3E, write signals and address signals are supplied to the RAMs (23A) and (23B) through the switch circuit (43). In this case, the write signal and the address signal have a frequency of 4f _H and are alternately arranged in the RAM (23A), (23
B) While being supplied, at this time, the running direction of the tape (1) at the time of recording is detected from the user bit in the detection circuit (44) and supplied to the forming circuit (41), and the tape (1) at the time of recording is supplied. When the running direction and the running direction of the tape (1) at the time of reproduction coincide, the address signal is changed from the head address of the RAM (23A), (23B) to the end address, and the address signal is The offset in the final address direction is given by the length (period) of the header signal Ss. Therefore, the decoded signal Se is transferred to RAM (23A) and (23B).
The data is written alternately every 63 field periods and one line per field period so that the same address as that at the time of recording is obtained.

Further, in the forming circuit (4), a read signal and an address signal in which one field period is repeated are formed, and these signals are written to the RAMs (23A) and (23B) which are not written through the switch circuit (43). It is supplied alternately every 263 field periods. Therefore, FIG.
As shown in C and D, the RAMs (23A) and (23B) are read during the 263 field period during which this writing is not performed. In this case, this reading is repeated at a speed of frequency 3fc every 1 field period and alternately from the RAMs (23A) and (23B) every 263 field periods. Therefore, from the RAMs (23A) and (23B), the original signal Sd is repeated every one field period, and
The signal Sd is updated and read every 263 field periods.

Then, this signal Sd is supplied to the D / A converter (33), and therefore, the still image color video signal Sc updated every 263 field periods is taken out from the output terminal (34).

Further, during reproduction, the traveling direction of the tape (1) during recording is detected from the user's bit in the detection circuit (44), and the traveling direction of the tape (1) during recording and the traveling direction of the tape (1) during reproduction. When and are the opposite,
The address signals supplied to the RAMs (23A) and (23B) change from the last address to the first address in each track (2) and from the first address to the last address in one track (2). To be done. Therefore, even in the opposite case, the decoded signal Se is
Alternate every (263A) and (23B) every 263 field periods,
At the same time, one line is written every one field period so that the address becomes the same as that at the time of recording.

Therefore, even when the tape (1) is run in the direction opposite to the direction in which the tape is recorded for reproduction, a correct still image video signal can be obtained from the output terminal (34).

Thus, according to the present invention, a still image can be correctly reproduced immediately even when the tape (1) travels in the same direction during recording and during reproduction, and vice versa. Even if the running direction of the tape (1) is opposite to that of time, it is not necessary to feed the tape (1) to the recording start point of the still image, and therefore the access time at the time of reproduction can be shortened.

Further, the header signal Ss is recorded over a plurality of tracks (2), which is advantageous for dropout.

G ₂ Other Embodiments In the above, when the tape (1) travels in the opposite directions during recording and reproduction, when the signal Se is written to the RAM (23A), (23B) during reproduction, the write address Although the signal is changed from the final address to the start address, the write address signal may be changed from the start address to the end address and the read address signal may be changed from the end address to the start address.

Further, in the above description, the header signal Ss is recorded in the PCM data section (23), but it may be recorded in the index section (26) or the cue track. Alternatively, it may be frequency-multiplexed with the signal Sp and recorded together with the pilot signal for tracking servo.

Furthermore, in the above, the first few field periods in the signal Se (first few line periods in the signal Sd) are
Although the header signal Vs is used, for example, as shown in FIG.
(263 + Ss) field period (Ts is a few field period)
Is the write / read cycle of RAM (23A), (23B), the first few field periods Ts are the header signal Vs period, and the remaining 263 field periods are the original signal V
It can also be a period of r.

Also, a plurality of sections may be used for one still image.

H Effect of the Invention According to the present invention, it is possible to immediately reproduce a still image correctly even when the tape (1) travels in the same direction during recording and during reproduction, and vice versa. It is not necessary to feed the tape (1) to the recording start point of the still image even if the running direction of the tape (1) is opposite between the time of reproduction and the time of reproduction, and therefore the access time during reproduction can be shortened.

Further, the header signal Ss is recorded over a plurality of tracks (2), which is advantageous for dropout.

[Brief description of drawings]

FIG. 1 is a system diagram of an example of the present invention, and FIGS. 2 to 8 are diagrams for explaining the same. (21) to (26) are video signal recording systems, and (31) to (34) are reproduction systems thereof.

Claims (1)

[Claims] 1. A magnetic tape is obliquely run at a constant speed over a predetermined range of rotation with respect to a rotating peripheral surface of a rotary magnetic head, and a video signal of a still image is time-axis expanded and this time-axis expanded. The video signal is sequentially for each predetermined period
When the PCM signal is encoded into a PCM signal and the PCM signal is sequentially recorded on the magnetic tape as diagonal magnetic tracks for the predetermined period, the rotary magnetic head causes the PC to move from the magnetic track to the PC.
The M signal is sequentially reproduced for each of the above predetermined periods, and the reproduced PCM signal is sequentially decoded into the original time-axis expanded video signal, and the decoded video signal is sequentially written to the memory. The video signal of the still image is obtained by repeatedly reading the video signal from the memory, and the address when the video signal is written to the memory when the running direction of the magnetic tape is opposite during recording and playback of the video signal. A magnetic reproducing apparatus in which a change between a signal and an address signal at the time of reading is reversed for each address corresponding to the predetermined period.