JPH0522746A - Magnetic tape recorder and reproducing device - Google Patents

Abstract

PURPOSE:To appropriately record and regenerate a video signal of PAL mode as a still image in a magnetic tape recorder and regenerator for recording and regenerating a digital signal of still picture data using magnetic tape as a recording medium. CONSTITUTION:After a recording medium stores two screens or four fields of continuous image signal as still picture data in memories 8a and 8b, the recording medium records the stored video signal in magnetic tape 18. When regenerating the video signal, an output means once stores two screens of video signal read from magnetic tape 18 in memories 8a and 8b, and repeatedly read this two screens of video signal to prepare a regenerating signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape recording / reproducing apparatus for recording / reproducing a digital signal of still image data using a magnetic tape as a recording medium.

[0002]

2. Description of the Related Art As one of conventional recording / reproducing apparatuses, an audio signal is converted into a digital signal and recorded on a magnetic tape, and a digital signal recorded on the magnetic tape is converted into an audio signal and reproduced. Digital audio tape recorders (hereinafter abbreviated as DAT) are well known.

In the case of this DAT, when audio signals are converted into digital signals and recorded on a magnetic tape, information for error correction can be simultaneously recorded as sub information, so that some of the recorded information is missing. Even if a noise occurs, it can be repaired. Therefore, not only the original sound can be reproduced faithfully, but also the sound with very little noise can be reproduced.

By the way, among the above-mentioned conventional DATs, there are two operation modes, a two-channel mode in which two channels for individually recording two kinds of audio signals are set on a magnetic tape, and four kinds of audio signals. Record individually 4
There is one that allows selection of a 4-channel mode in which the channel is set to a magnetic tape.

Among them, in the 2-channel mode, two kinds of audio signals corresponding to two speakers arranged on the front left side and the right side with respect to the listener are recorded on the magnetic tape, and in the 4-channel mode, the listener is told. Front left side,
Four types of audio signals corresponding to four speakers arranged on the front right side, the rear left side, and the rear right side are recorded.

Further, in the case of the above four-channel mode, an audio signal is recorded in two of the channels and a still image video signal is recorded in the remaining two channels, and the audio signal and the video signal are recorded from one magnetic tape. A system in which reproduction is performed at the same time is also conventionally known.

In the case of this system, for example, two image memories for respectively storing still image video signals for one screen are prepared, and at the time of recording, the video signal for one screen is analog-recorded before being recorded on the magnetic tape. A digital (hereinafter referred to as A / D) conversion circuit converts the signal into a digital signal, which is once written sequentially to one of the two image memories, and then a digital video signal for one screen is output from the image memory. It is read and recorded on two channels of the magnetic tape.

At this time, an audio signal input in parallel with the video signal is also converted into a digital signal by another D / A conversion circuit, sequentially written in the remaining image memory, and then read out from the magnetic tape. Recorded in. As a result, a video signal for one screen and an audio signal such as narration corresponding to this screen are recorded in parallel on the magnetic tape.

On the other hand, at the time of reproduction, the digital video signal for one screen read from the magnetic tape is once written sequentially in one of the image memories, and after the writing is completed,
A video signal for one screen is repeatedly read from the image memory, and the read video signal is converted into an original analog video signal by a digital-analog (referred to as D / A) conversion circuit and reproduced.

At this time, the digital audio signal read from the magnetic tape in parallel with the digital video signal is also converted into an analog audio signal by the D / A conversion circuit and reproduced. As a result, when a still image video signal for one screen is reproduced, an audio signal such as narration corresponding to the still image is reproduced in parallel.

[0011]

By the way, in the above-mentioned conventional DAT, NTSC (Nation) is used as still image data.
There is no problem in recording and reproducing video signals of the al Television System Committee) system, but PAL (Phase Alternati
on / line) video signal recording / playback,
There is a problem as explained below.

That is, regarding the repetitive characteristics of the phase of the scanning line in the PAL system video signal, assuming that the head of the first field, that is, the first scanning line is a positive phase, the last part of the first field, that is, the first half of the 313th scanning line is The phase becomes the positive phase, the beginning of the second field, that is, the latter half of the 313th scanning line becomes the positive phase, and the end of the second field, that is, the 625th scanning line also becomes the positive phase.

Therefore, the first scanning line of the third field starts from the negative phase and ends in the third field, that is, the 31st field.
The first half of the three scanning lines has a negative phase, the second half of the leading 313th scanning line of the fourth field has a negative phase, and the last half of the fourth field, that is, the 625th scanning line has a negative phase.

Therefore, in order to correctly record and reproduce the PAL video signal as still image data, at least 4
It is necessary to record continuous video signals for one field as a unit.

However, in the conventional DAT, an image memory having a storage capacity of one screen, that is, two fields is prepared as an image memory for temporarily storing a still image video signal before recording it on a magnetic tape. If you capture and record the PAL video signal for one screen with this DAT and record and play it back, the phase of the scanning lines will be aligned for each screen and the still image that is played back will not be colored. The problem is that the adverse effect of

Therefore, an object of the present invention is to provide a magnetic tape recording / reproducing apparatus capable of properly recording / reproducing a PAL video signal as still image data.

[0017]

SUMMARY OF THE INVENTION The present invention is a magnetic tape recording / reproducing apparatus for recording / reproducing a digital signal of still image data using a magnetic tape as a recording medium, and a memory for storing still image data for two screens and recording. Recording means for temporarily storing two screens of still image data in the memory and then recording the data on a magnetic tape while sequentially reading from the memory,
An output unit is provided, which temporarily stores the two screens of data read from the magnetic tape at the time of reproduction in the memory at the time of reproduction, and then repeatedly reads out the two screens of data from the memory and outputs it as a reproduction signal. It is a magnetic tape recording / reproducing device that operates.

[0018]

According to the present invention, a continuous video signal for two screens, that is, for four fields, is temporarily stored in a memory as still image data, then recorded on a magnetic tape, and read from the magnetic tape during reproduction. Since the video signals for the screen are temporarily stored in the memory and the video signals for the two screens are repeatedly read and used as the reproduction signal, an appropriate still image can be recorded / reproduced even when the PAL system video signal is recorded / reproduced.

[0019]

1 is a block diagram showing the basic structure of a magnetic tape recording / reproducing apparatus according to an embodiment of the present invention.

The magnetic tape recording / reproducing apparatus of this embodiment is
This is a DAT capable of recording and reproducing in the 4-channel mode, in which two channels out of the four channels are assigned to audio signals and the remaining two channels are assigned to video signals.

In this case, the two types of audio signals are input terminals R
0 and L0 are input. These input signals are A
It is input to the / D conversion circuits 3 and 4. A / D conversion circuit 3,
4, at a sampling frequency of 32 KHz, for example,
The input analog signal is sampled and converted into, for example, 12-bit digital audio signals d1 and d2. The digital audio signals d1 and d2 are serial-parallel (hereinafter referred to as S / P) from the A / D conversion circuits 3 and 4.
It is inputted to the conversion circuit 5, and here, for example, 8 bits are inputted in parallel to the data bus 19.

The video signal is input from the input terminal V0 A
It is input to the / D conversion circuit 2 and converted into a digital video signal d3. The A / D conversion circuit 2 samples the input analog signal, converts it into an 8-bit digital signal d3, and inputs it in parallel to the data bus 19. The video signal is also input to the odd field detection circuit 1, and the odd field detection circuit 1 outputs the odd field detection signal G1.

The digital video signal d3 is sent to the data bus 19
It is written in one of the two image memories 8a and 8b connected to. These image memories 8a and 8b have a capacity capable of storing two screens of the input digital video signal d3, that is, four fields, and the digital video signal d3 for two screens is written in the image memory 8a.

The digital audio signal d4 given from the S / P conversion circuit 5 to the data bus 19 is a digital video signal d.
The other image memory 8 which is not used for storing 3
written to b.

The digital audio signal d4 written in the image memory 8b is not read out until the writing of the digital audio signal in all the storage areas of the image memory 8b is completed, and the storage in all the storage areas is completed. Then, the digital audio signals previously stored are sequentially read and given to the data bus 19.

The digital audio signal read onto the data bus 19 in this way is parallel-serial (hereinafter,
A digital video signal given to the conversion circuit 7 and stored in the image memory 8a is called a P / S conversion circuit 6
Given to.

The digital audio signal that is seriously derived from the P / S conversion circuit 7 is input to the input terminal 2 of the changeover switch 9.
It is given to 2 and 23 in common. A digital video signal that is seriously derived from the P / S conversion circuit 6 is applied to the input terminal 21 of the changeover switch 9.

The output terminal 2 of the changeover switch 9
4 and the input terminals 21, 22, and 23 are sequentially and cyclically conducted, and the digital signal d5 thus derived from the output terminal 24 is given to the recording signal processing unit 10.

In the recording signal processing unit 10, the input digital signal d5 is subjected to processing such as addition and modulation of information called parity for error correction and the like, and after such signal processing. Is recorded on the magnetic tape 18 by a rotary head (not shown) or the like.

At the time of reproduction, the signal recorded on the magnetic tape 18 is given to the reproduction signal processing section 12 from the rotary head. The reproduction signal processing unit 12 performs error correction processing and the like with reference to demodulation and parity, and the digital signal d6 thus reproduced is given to the input terminal 34 of the changeover switch 13.

The output terminals 32 and 33 of the changeover switch 13 are connected to the D / A conversion circuits 16 and 17, respectively. By the switching operation of the changeover switch 13, which will be described later, the input terminal 34 and the output terminals 31 to 33 are sequentially and cyclically connected.

In this way, the D / A conversion circuits 16 and 17 are
To the listener, for example, digital audio signals d7 and d8 corresponding to the speakers arranged on the front right side and the front left side are given to the listener, respectively, and the D / A conversion circuit 16,
At 17, it is converted into an analog audio signal and is led to the output terminals R1 and L1 of the magnetic tape recording / reproducing apparatus.

At this time, the digital video signal d9 derived from the input terminal 34 of the changeover switches 9 and 13 to the output terminal 31 is given to the S / P conversion circuit 14 and input to the data bus 19 in parallel, for example, every 8 bits. Be done.
The digital video signal d10 input in this way is
The data is input to either one of the image memories 8a and 8b. At this time, the stored contents are supplied from the data bus 19 to the D / A conversion circuit 15 from the other one of the image memories 8a and 8b.

While the digital video signal d10 is being written to one of the image memories, the stored contents are read from the other image memory, and such a reading process is cyclic. Has been done in.

As a result, at the output terminal V1 connected to the D / A conversion circuit 15, a video signal representing a still image corresponding to the digital video signal stored in the other one of the image memories is continuously derived. Will be done.

Such a video signal is, for example, a CRT.
It is input to a display device such as a (cathode ray tube) and the still image is displayed on its display surface.

FIG. 2 is a timing chart for explaining the changeover operation of the changeover switches 9 and 13 in the magnetic tape recording / reproducing apparatus. 2 (1) and 2
(2) shows the changeover control signals LR and LR1 given to the changeover switches 9 and 13, respectively, and FIG. 2C shows the changeover operation of the changeover switches 9 and 13.
(4) shows the digital signal d5 (d6) derived to the output terminal 24 (input terminal 34) of the changeover switches 9 and 13, and FIG. 2 (5) shows the recording signal processing section 10 (reproduction signal processing section 12). ) Shows a clock signal CK1 generated inside the parentheses.

In FIG. 2C, the input terminals 21, 22, 23 (output terminals 31, 32, 3) connected to the output terminal 24 (input terminal 34) of the changeover switches 9, 13 are output.
The change of 3) is shown.

The change-over switches 9 and 13 have a change-over control signal L.
When both R and LR1 are low level,
The output terminal 24 (input terminal 34) is electrically connected to the input terminal 22 (output terminal 32). When the switching control signal LR1 is at low level and the switching control signal LR1 is at high level, it is conducted to the input terminal 21 (output terminal 31).

During the period W1 between times t1 and t2, the switching control signals LR and LR1 are both at the low level, so that the output terminal 24 is connected to the input terminal 22. As a result, the recording signal processing unit 10 is supplied with the digital audio signal from the P / S conversion circuit 7. The digital audio signal given to the recording signal processing unit 10 during this period W1 corresponds to, for example, the digital audio signal corresponding to the speaker arranged on the front right side of the listener.

The recording signal processing unit 10 takes in the digital signal d5 derived from the output terminal 24 bit by bit in synchronization with the rising edge of the clock signal CK1.

During the period W2 between times t2 and t3, the switching control signal LR is at high level and the switching control signal LR1 is at low level. Therefore, during this period, P /
The digital audio signal derived from the S conversion circuit 7 to the input terminal 22 is captured by the recording signal processing unit 10. This digital audio signal will therefore correspond to the speaker located to the front left of the listener.

During the period W3 between times t3 and t5, the changeover control signal LR1 is at high level, so that the output terminal 24 of the changeover switch 9 is conducted to the input terminal 23. Therefore, during this period W3, the digital video signal from the P / S conversion circuit 6 is set to 1 in the recording signal processing unit 10.
Input bit by bit.

At time t4, the switching control signal LR rises, so that the switching control signal LR changes from time t4 to t5.
However, the changeover switch 9 does not perform the changeover operation in response to the change in the changeover control signal LR while the changeover control signal LR1 is at the high level.

Although the sampling frequency in the A / D conversion circuits 3 and 4 is selected to be 32 KHz, for example, as described above, the switching control signal LR1 corresponds to this.
Has a frequency of 32 KHz. Further, the analog audio signal input in the A / D conversion circuits 3 and 4 is 12
Since they are converted into the bit digital audio signals d1 and d2, the digital audio signals taken into the recording signal processing unit 10 in the periods W1 and W2 are 12-bit digital signals. Therefore, the digital video signal taken into the recording signal processing unit 10 in the period W3 becomes a 24-bit digital signal.

In this manner, after recording the digital video signal on the magnetic tape 18, the digital audio signal corresponding to the recorded digital video signal is recorded. That is, the digital audio signal corresponding to the digital video signal is
It is recorded on the magnetic tape 18 after a delay of about 2.5 seconds from the digital video signal.

Next, the operation during reproduction will be described. A signal read from the magnetic tape 18 by a rotary head or the like is given to the reproduction signal processing unit 12, and a clock signal C
Each bit is serially derived in synchronization with the fall of K1. Thus, during the period W1, the digital signal d
6 is given to the D / A conversion circuit 16 as a digital audio signal d7, given to the D / A conversion circuit 17 as a digital audio signal d8 during the period W2, and given to the S / P conversion circuit 14 during the period W3. Given as d9.

That is, the digital signals d6 derived in the periods W1 and W2 are the front right side of the listener,
It is a digital audio signal corresponding to the speaker arranged on the left side, and is a digital signal d6 derived in the period W3.
Supports digital video signals.

The digital video signal d10 output from the S / P conversion circuit 14 is sequentially written in, for example, one image memory 8a. The writing of the digital video signals for four fields to the image memory 8a is completed in the same time as the time required for reading the digital video signals from the image memory 8a to the recording signal processing unit 10 during recording.

When the writing of the digital video signals for two screens is completed in this way, all the digital video signals from the written image memory 8a are input to the D / A conversion circuit 15. Such a read operation of the video signals for two screens is repeatedly performed continuously.

While the digital video signal is being read from the image memory 8a, the digital video signal corresponding to the next still image is written to the other image memory 8b.

In this way, the image memories 8a and 8b are
While the digital video signal is being read from one of the image memories, the digital video signal is being written to the other image memory.

Detection of odd fields in the odd field detection circuit 1 will be described with reference to FIGS. 3 and 4. In the sync signal in the decoded video signal processed by the television receiver, the phase relationship between the horizontal sync signal and the vertical sync signal is different between the odd field and the even field as shown in FIG. Odd field detection is performed by.

In the odd field detection circuit 1, as shown in FIG.
When a vertical sync signal characteristic of an odd field as shown in FIG. 4A, which is different from the vertical sync signal in the even field shown in FIG. 4B, is detected, a low level signal G1 is output between the fields. .. When the output G1 from the odd field detection circuit 1 becomes low level, the recording signal processing unit 10 outputs the memory write signal MW1 which becomes low level for four fields to the memory controller 11. In response to this, the memory controller 11 performs an operation of writing data in the memory 8a only while the memory write signal MW1 is at the low level.

[0055]

As described above, according to the magnetic tape recording / reproducing apparatus of the present invention, after the video signal for two continuous screens, that is, for four fields, is temporarily stored in the memory as the still image data by the recording means, This is recorded on a magnetic tape, and at the time of reproduction, the video signals for two screens read from the magnetic tape by the output means are temporarily stored in the memory, and the video signals for these two screens are repeatedly read and used as reproduction signals. Therefore, an appropriate still image can be recorded and reproduced even when the PAL system video signal is recorded and reproduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a magnetic tape recording / reproducing apparatus which is an embodiment of the present invention.

FIG. 2 is a timing chart showing a switching operation of a changeover switch in the magnetic tape recording / reproducing apparatus of the embodiment.

FIG. 3 is a timing chart showing an operation of writing a video signal into an image memory in the magnetic tape recording / reproducing apparatus of the embodiment.

FIG. 4 is a waveform diagram showing a sync signal in a composite video signal.

[Explanation of symbols]

 1 Odd field detection circuit 2, 3, 4 A / D conversion circuit 5 S / P conversion circuit 6, 7 P / S conversion circuit 8a, 8b Image memory 9, 13 Changeover switch 10 Recording signal processing unit 11 Memory controller 12 Playback signal Processing unit 14 S / P conversion circuit 15, 16, 17 D / A conversion circuit 18 Magnetic tape 19 Data bus

Claims (1)

Claim: What is claimed is: 1. A magnetic tape recording / reproducing apparatus for recording / reproducing a digital signal of still image data using a magnetic tape as a recording medium, and a memory for storing still image data for two screens, and a memory for recording two images. After temporarily storing still image data for the screen in the memory, recording means for sequentially recording the data on the magnetic tape while reading from the memory, and temporarily storing the data for two screens read from the magnetic tape at the time of reproduction in the memory. After that, the magnetic tape recording / reproducing apparatus is provided with an output means for repeatedly reading out the data for the two screens from the memory and outputting it as a reproduction signal.