JP2695306B2 - Magnetic tape recording / reproducing device - Google Patents

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 and reproducing apparatus for recording and reproducing digital signals of still picture data using a magnetic tape as a recording medium.

[0002]

2. Description of the Related Art As one conventional recording / reproducing apparatus, an audio signal is converted into a digital signal and recorded on a magnetic tape, and a digital signal recorded on a magnetic tape is converted into an audio signal and reproduced. A digital audio tape recorder (DAT) is well known.

[0003] In the case of this DAT, when an audio signal is converted into a digital signal and recorded on a magnetic tape, information for error correction can be simultaneously recorded as sub-information. Can be repaired even if it occurs, so that not only the original sound can be faithfully reproduced, but also a sound with very little noise can be reproduced.

Some of the above-mentioned conventional DATs include two-channel mode in which two channels for individually recording two types of audio signals are set on a magnetic tape, and four types of audio signals. Record 4 individually
In some cases, a 4-channel mode in which a channel is set to a magnetic tape can be selected.

Among them, in the 2-channel mode, two kinds of audio signals corresponding to the two speakers arranged on the front left and right sides with respect to the listener are recorded on the magnetic tape, and in the 4-channel mode, the listener is informed. 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.

In the case of the 4-channel mode, an audio signal is recorded on two of the channels and a still image video signal is recorded on 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. It is converted into a digital signal by a digital (hereinafter referred to as A / D) conversion circuit, is once written into one of the two image memories sequentially, 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, the 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 (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 a narration corresponding to the still image is reproduced in parallel.

[0011]

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, the repetitive characteristic of the phase of the scanning line in the PAL system video signal is such that when the beginning of the first field, that is, the first scanning line has a positive phase, the last part of the first field, that is, the first half of the 313th scanning line, The phase becomes the positive phase, and the beginning of the second field, that is, the latter half of the 313th scanning line also becomes the positive phase, and the last of the second field, that is, the 625th scanning line also becomes the positive phase.

For this reason, the first scanning line of the third field starts from a negative phase and ends at the last of the third field, that is, the 31st scanning line.
The first half of the third scanning line also has a negative phase, the second half of the 313rd scanning line at the beginning of the fourth field also has a negative phase, and the last of the fourth field, that is, the 625th scanning line also 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 for 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 PAL video signals for one screen with this DAT, and record and play it, the phase of the scanning line will be aligned for each screen and the still image that is played back will not be colored. There will be a problem in that

Therefore, an object of the present invention is to provide a magnetic tape recording / reproducing apparatus capable of properly recording / reproducing not only the NTSC system video signal but also the PAL system video signal as still image data.

[0017]

According to the present invention, (a) a magnetic tape, (b) a rotary head for writing and reading on the magnetic tape, and (c) two screens each of which is composed of two fields. First memory 8a having a capacity for storing a digital signal of still image data for one minute, and (d) a second memory 8a having a capacity for storing a digital signal for still image data of two screens, each screen including two fields. A memory 8b, (e) a field detecting means for detecting the first field of still image data for two screens, and (f) a controlling means, which responds to the output of the field detecting means at the time of recording, The digital signals of the still image data of two screens to be written are written in the first memory 8a, and the digital signal of the audio data corresponding to the still image data stored in the first memory 8a is written. When the signal is written to the second memory 8b and the writing to the first and second memories 8a and 8b is completed, the rotary tape is applied to the magnetic tape and the digital signal of the audio data stored in the second memory 8b and While recording the digital signal of the still image data stored in one memory 8a, at the time of reproduction, the digital signal of the audio data is read out and derived from the magnetic tape by the rotary head. Read the digital signal to read the first or second
Write to one of the memories 8a and 8b, and during the writing period to the one or the second memory 8a or 8b of any one of the memories, the digital signal of the still image data from the other is equal to the writing time. In the readout period of
A magnetic tape including a control means for reading out, deriving, and reading from the first or second memory 8a, 8b where the writing is completed when the writing to the first or second memory 8a, 8b is completed. It is a recording / reproducing device.

[0018]

According to the present invention, the first and second memories 8a,
8b has a capacity to store a digital signal of still image data for 2 screens, that is, for 4 fields, and when recording with a rotary head on a magnetic tape, the field detecting means is the first of the still image data for 2 screens. By detecting the field of, the digital signal of the still image data for two screens is written in the first memory 8a, and the digital signal of the audio data is written in the second memory 8b, and the first and second memories 8a, 8a, When the writing to 8b is completed, the digital signal of the audio data read from the second memory 8b and the digital signal of the still image data read from the first memory 8a are recorded on the magnetic tape. In reproducing the digital signals of the still image and audio data written on this magnetic tape, the rotary head reads the digital signal of the audio data from the magnetic tape and derives it as it is. To read the digital signal of the first or second memory 8
a, 8b is written, and during this writing period, a digital signal of still image data is read from the other of the first and second memories 8a and 8b, and the writing time and the reading time are the same. Yes, when the writing is completed, the digital signal of the still image data is read out from the first or second memory 8a, 8b where the writing is completed. In this way, since the still image data for two screens are repeatedly read and used as a reproduction signal, an appropriate still image can be recorded / reproduced even when recording / reproducing still image data of not only the NTSC system but also the PAL system. .

[0019]

1 is a block diagram showing the basic construction 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.

Two types of audio signals in this case are input terminals R
0, L0. 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 the. 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 stored in advance are sequentially read and given to the data bus 19.

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

The digital audio signal serially 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. The digital video signal serially 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 supplied to the recording signal processing unit 10.

In the recording signal processing section 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, respectively, are applied to the listener, and the D / A conversion conversion circuit 16,
At 17, the analog audio signal is converted into an analog audio signal and led to 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 change-over 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. Being 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 image memory is continuously derived. Will be done.

Such a video signal is output from, for example, a CRT.
(Cathode ray tube) or the like, and the still image is displayed on the 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. FIG. 2 (1) and FIG.
(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 the 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 connected.
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). Further, when the switching control signal LR1 is at the low level and the switching control signal LR1 is at the 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, a digital audio signal from the P / S conversion circuit 7 is supplied to the recording signal processing unit 10. The digital audio signal given to the recording signal processing unit 10 in this period W1 is, for example,
It corresponds to the digital audio signal corresponding to the speaker arranged on the front right side with respect to the listener.

In the recording signal processing section 10, the digital signal d5 derived from the output terminal 24 is taken into the inside thereof 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 from time t3 to t5, the changeover control signal LR1 becomes 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.
Entered 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.

The sampling frequency in the A / D conversion circuits 3 and 4 is selected to be, for example, 32 KHz as described above, but the switching control signal LR1 is corresponding 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 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.

Thus, 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. The signal read from the magnetic tape 18 by the rotary head is given to the reproduction signal processing unit 12, and the clock signal CK1
Are serially derived bit by bit in synchronization with the trailing edge of. Thus, in the period W1, the digital signal d6 is given to the D / A conversion circuit 16 as the digital audio signal d7, in the period W2 to the D / A conversion circuit 17 as the digital audio signal d8, and in the period W3. It is given to the S / P conversion circuit 14 as a digital video signal d9.

That is, the digital signals d6 derived in the periods W1 and W2 are the front right side of the listener,
A digital audio signal corresponding to the speaker arranged on the left side, which 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 to read 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 are input to the D / A conversion circuit 15 from the image memory 8a for which the writing has been completed. Such a read operation of the video signals for two screens is repeatedly and continuously performed.

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 in the other image memory 8b. That is, the reading period of either one of the image memories 8a and 8b is equal to the writing period of the other one.

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.

Next, detection of an odd field in the odd field detection circuit 1 will be described with reference to FIGS. For 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. 4, so this should be used. Odd field detection is performed by.

In the odd field detection circuit 1, FIG.
As shown in FIG. 4A, when a vertical sync signal characteristic of an odd field, 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-numbered field detection circuit 1 becomes low level, the recording signal processing unit 10 outputs to the memory controller 11 the memory write signal MW1 which becomes low level for four fields. In response to this, the memory controller 11 performs the operation of writing data in the memory 8a only while the memory write signal MW1 is at the low level.

[0055]

According to the magnetic tape recording / reproducing apparatus of the present invention, when recording is performed on the magnetic tape by the rotary head, the digital signals for two continuous screens, that is, for four fields are recorded as still image data. Alternatively, after the data is once written in the second memories 8a and 8b, it is recorded on a magnetic tape, and at the time of reproduction, a digital signal of two screens of still image data read by the rotary head from the magnetic tape is temporarily transferred to the first or Writing to either one of the second memories 8a and 8b, reading from the other, and thus repeatedly reading from the first or second memories 8a and 8b alternately for every two screens of still image data, a reproduction signal is obtained. Therefore, even when a digital signal of still image data of not only the NTSC system but also the PAL system is recorded and reproduced, an appropriate still image can be recorded and reproduced. Moreover, the digital signal of the audio data corresponding to each still image data can also be written and read on the magnetic tape by the rotary head. Further, according to the present invention, it is possible to reliably record each digital signal of still image data and audio data on the magnetic tape, and prevent recording of useless data.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a magnetic tape recording / reproducing apparatus according to 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 synchronization 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 reproduction signal Processing unit 14 S / P conversion circuit 15, 16, 17 D / A conversion circuit 18 Magnetic tape 19 Data bus

Claims (1)

(57) [Claims] 1. (a) a magnetic tape; (b) a rotary head for writing and reading on the magnetic tape; (c) a digital signal of two screens of still image data in which each screen is composed of two fields. A first memory 8a having a capacity for storing the following: (d) a second memory 8b having a capacity for storing a digital signal of two screens of still image data, each screen having two fields, and (e) 2 Field detection means for detecting the first field of the still image data for the screen, and (f) the control means, which responds to the output of the field detection means at the time of recording, and is a still image for two screens to be written on the magnetic tape. The digital signal of the data is written in the first memory 8a, and the digital signal of the audio data corresponding to the still image data stored in the first memory 8a is written in the second memory 8b. When writing into the first and second memories 8a and 8b is completed,
The rotary head records the digital signal of the audio data stored in the second memory 8b and the digital signal of the still image data stored in the first memory 8a on the magnetic tape, while rotating the magnetic tape during reproduction. With a formula head, while reading and deriving a digital signal of voice data,
The digital signal of the still image data for two screens is read out and written in either one of the first or second memories 8a, 8b, and the one of the first or second memories 8a, 8b is read.
During the writing period to b, the digital signal of the still image data is read and derived from the other in the same reading period as the writing time, and the writing to the first or second memories 8a and 8b is completed. A magnetic tape recording / reproducing apparatus comprising: a control unit for reading from the first or second memory 8a, 8b for which writing has been completed.