JPS5925286B2 - Optical multichannel recording and playback method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention digitizes video signals, audio signals, and other electrical signals, converts these digital signals into multi-channels, converts these multi-channel electrical signals into multi-channel optical signals, and converts them into multi-channel optical signals. The aim is to achieve multi-channel fixed head recording and playback, which has been difficult to achieve with tape head systems, by using optical recording media, especially those with a wide video signal band.
The purpose of this system is to optically record and reproduce broadband video signals that would otherwise be unreasonable in terms of frequency with conventional magnetic tape-head systems.

Conventionally, magnetic tape and head systems have often been used for recording and reproducing video and audio signals.

For example, efforts have been made to increase the recording density by using rotating heads to record and reproduce video signals, but when trying to record signals with a video band of about 30 MRz, current broadcasting When using a commercial VTR system, the relative speed of the tape and head is 200 m/
Sec, and the frequency passing through the head is 100M.
Hz, many difficult problems arise, such as the problem of contact between the head and tape, and the problem of the frequency characteristics of the magnetic permeability of the head. In addition, when recording and reproducing using an optical system, holographic recording is well known, but in this case, it is necessary to use a light source with good coherence, and it is necessary to convert electrical signals into optical signals. It is necessary to provide a spatial modulator and pass the above-mentioned light with good coherence through it.

The present invention solves these conventional problems. One embodiment will be described below with reference to the accompanying drawings. FIG. 1 shows an embodiment of an apparatus for implementing the method of the present invention.

In the figure, 1 is a light source such as a laser.

The light emitted from the light source 1 enters the optical distributor 2 and is divided into, for example, eight channels of light, which are output as uniform light. These eight lights are guided to the electrical signal/optical signal converter 3 optically or through a glass fiber. The electrical signal/optical signal converter 3 functions to pass or not pass light depending on the electrical signal, and is composed of, for example, an optical modulator or an optical deflector. On the other hand, the electrical signal enters the analog-to-digital converter 5 through the input terminal 4. Now, assuming that this electrical signal is a video signal with a band of 30 MHz, it is sufficient for the analog-digital converter 5 to output 8 bits sampled at 100 MHz. The 8-bit output from the analog-to-digital converter 5 is connected to the eight electrical signal-to-optical signal converters 3. Therefore, the electric signal from the analog-to-digital converter 5 converts the electric signal into the optical signal converter 3.
The eight channels of light guided by the light become a signal containing information. Reference numeral 6 denotes an optical switch operated by an electric signal, and in this embodiment, 30 optical switches 6 are arranged in parallel.

Eight channels of optical signals from the electrical signal and optical signal converter 3 are guided and inputted to each of the above-mentioned optical switches 6 through, for example, a glass fiber. When the first switch 6 is set to 0N and passes 8 channels of signals from the electrical signal to optical signal converter 3, the other 29 optical switches are set to 0FF. The switching of this optical switch 6 is based on the sampling frequency of the analog-to-digital converter 5, for example, 100MHz in the above explanation.
z signal is passed through a pulse circuit 12. Then, at the time of the next sampling from the analog-digital converter 5, the second optical switch is set to 0N state, and all others are set to 0FF.
shall be. In this way, switch 30 optical switches 6 one after another, and after switching the 30th optical switch, return to the original 1st position again.
The output of the optical switch 6, a total of 240 channels, includes 8
Information for each channel is transmitted at a frequency of 100 MHz, and when the signal is output 30 times for each 8 channels, the signal will be output again at the original 8 channels. Also, in the same way as 240 channels, 8 channels each,
As shown in FIG. 2, to output optical information at a frequency of 100 MHz, instead of using the optical switching device 6 shown in FIG.
The output of the electrical signal/optical signal converter 3 may be combined into 8 channels and deflected at, for example, 30 points by the optical deflector 7 so that the light enters the 30 light receiving portions 6 described above.

In this case, the deflection speed of the optical deflector 7 will be 100 MHz. In order to absorb slight differences in deflection angles, the 30 light-receiving parts 6 that collectively receive light in 8 channels are used as the receivers of the glass fibers when 240 glass fibers are used for the light-receiving part 6. As shown in FIG. 3, eight wires are spread out at a time, or a lens-shaped element is added to the tip so that it can easily receive optical signals, as shown in FIG. 4 (a). If eight glass fibers are grouped together and their tips are widened as shown in FIG. 3, the thickness of the light beam can be made slightly thicker, and the accuracy of the deflection position is not required as much.

Also, as shown in Figure 4A, if a lens-shaped object is added to the tip of the glass fiber, the light can be captured by the fiber if it enters an appropriate part of the lens, so in this case as well. Deflection position accuracy becomes slightly easier. In this case, instead of attaching a lens-shaped object to the tip of each glass fiber as shown in Figure 4, the fiber itself is processed so that the tip becomes lens-shaped. Of course, it's a good thing. In addition, in the above embodiment, as a method of converting an 8-bit digital signal by sampling at 100 MHz into a 240-channel optical signal, a method is described in which a single light source is used to convert an 8-channel electrical signal into an optical signal. However, for example, a method can be considered in which one light source is divided into 240 channels, a 240-channel electrical signal-to-optical signal converter is provided, and this 240-channel converter converts 8 channels at a time. Furthermore, instead of one light source, for example, as shown in FIG. 5, there are eight light sources 1', and the eight light sources 1'
It can be controlled 0N-0FF by electrical signals,
It is also possible to connect eight electrical signal-to-optical signal converters 3 to the light from each light source 1' to convert the electrical signal into an optical signal.

In this case, the method described above may be used to convert the 8-channel information into 240-channel information. Furthermore, instead of installing eight light sources, for example, as shown in FIG. 6, 240 light sources 14 such as light emitting diodes can be provided, and optical signals can be given to each of eight light sources to obtain optical information.

6} Here, the video signal inputted from the input terminal 4 is converted into a digital signal by the analog-to-digital converter 5, and a total of 240 signals of 8 bits each, for example, 30 groups, are output.

Here, A, b...... are switch circuits operated by the signal output from the analog-digital converter 5 through the pulse circuit 13. For example, if only the first switch circuit a is 0N, the other switches is 0FF first, then when b becomes 0N, the others become 0FF, and so on, the ones that become 0N move one after another. In other words, the signal is transmitted to 240 light sources in 8-bit increments, and in the end, 240 optical signals can be extracted. This 24
It is also possible to place zero light sources, such as semiconductor lasers, on one chip and take out 240 glass fibers from the one chip IC.

On the other hand, as shown in FIG.
With 15-bit memory, 8-bit electrical signals can be stored in 240-bit memory, and 24-bit electrical signals can be stored at one time.
It is also possible to provide electrical signals to zero light sources 14.

In FIG. 7, a video signal input from an input terminal 4 enters an analog-to-digital converter 5, and the output of this analog-to-digital converter 5 is stored in a 240-bit memory 15.
First of all, save it.

This stored signal is transmitted to 240 light sources 14 at a time by a control signal from the analog-digital converter 5.
, and a 240-channel optical signal is obtained. In this case, the 240-bit memory 15 must always store the incoming signals while outputting 240 bits at a time, so the 7th
The inside of the 240-bit memory 15 shown in the figure actually has, for example, a 240x3720-bit memory, and when a signal is stored in the first 240-bit memory group, the second 240-bit memory is stored. The signals are transferred to a third 240-bit memory group, and the third memory provides signals to 240 light sources 14 at a time. and the first
When the first 240-bit memory group becomes full, the signal is sent to the second 240-bit memory group, and the signal is transferred to the first 240-bit memory group.
The stored signal of the memory group of bits is transferred to the third 24 bits.
Put it in a group of 0-bit memories. In this way, the first and second
It is necessary to alternately enter the signal into one group of 240-bit memories, transfer it to a third memory, and then activate the 240 light sources 14.

The 240 channels of optical signals thus created are guided onto a recording tape 9 by a glass fiber 18, for example, as shown in FIG.

240 of these glass fibers 18 are lined up in a row and their tips are aligned. The optical conductive portion of the glass fiber is thin, and some are 3 to 5 μm thick for single mode use, but for example, as shown in Fig. 8, the thickness of the fiber is 1001 tm and the thickness of the optical conductive portion is 501 mm. 1.
In order to make the width 50 μm x 1 μm, a shielding plate 17 with a 1 μm slot 6 is provided on the front surface of the fiber 18.
so that the light comes out.

With such a head section, if you try to record a 100MHz 18-bit signal, the tape speed will be 3.3
The width of the head of the 3m/Sec124O channel is 24m.
m1 konaru. In each of the above-mentioned embodiments, a case has been described in which a glass fiber is used to guide 240 channels of light onto the recording tape 9, but in addition, for example, a precise lens system may be used to guide 240 channels of light onto the recording tape 9. It is also possible to lead to the top.

In the above manner, an electrical signal is converted into an optical signal, and the optical signal is 0N-
This means that 0FF can be recorded on the tape in a direction crossing the running direction of the tape.

In FIG. 1, numeral 10 indicates a 240-channel detector, and numeral 11 indicates a circuit processing section including a digital-to-analog converter. To reproduce the signal recorded on the tape 9 using the above method, a uniform light is applied to the glass fiber 18 and the signal is reproduced by the detector 10.

Fig. 1 shows a method of reading light by transmitting it through the recording tape 9, but it is also possible to change the angle between writing and reading the 240-channel glass fiber and read it by reflection. It is also possible. Also, the first
A reflector such as a mirror is placed at the position of the detector 10 shown in the figure.
Return the readout light to the glass fiber of channel 0,
Information can also be read out on the light source side. FIG. 9 shows a specific schematic configuration of the detector 10.

In this case, the detector is constructed by arranging 240 detection elements 101 in a straight line. Reading light of 8 bits each is applied to the detection elements 101, and the information output from the detector is sent to the circuit processing section 11. Converts digital to analog to obtain the original video signal. FIG. 10 shows a specific example of the configuration of another detector. In this case, while 240 channels of readout light are applied to the detection element 101 at once,
At the time of readout, the detector is sequentially scanned and the signal is read out. In this case, 240
The arrangement of the detection elements 101 in the channel is such that when writing 8 bits at a time, the information is recorded with a shift of 8 bits due to the movement of the tape 9, so in order to match this shift, the 240 detection elements 101 are arranged in 8 bits. Arrange them with a slight deviation between each one. Note that at this time, by making the light-receiving portion of the detection element 101 larger than the size of the recorded light, it is virtually unnecessary to create this deviation. By using the above method, video, audio, and other signals can be converted into digital optical signals for recording and reproduction.

As is clear from the above embodiments, according to the present invention, electrical signals can be recorded optically, thereby making it possible to record and reproduce high frequency signals that are difficult to respond to with magnetic recording or the like.

Furthermore, since hologram technology is not used, the light source does not need to be coherent. Furthermore, although the case of 240 channels has been explained as an example, if the method of this invention is adopted, the head part will be in a fixed state, so
The only mechanically moving part is the running of the tape, which has the advantage of being easier to control and having a simpler mechanism.

[Brief explanation of drawings]

FIG. 1 is an overall external view of an apparatus for realizing an optical multi-channel recording and reproducing method according to an embodiment of the present invention;
FIG. 2 is a diagram showing another embodiment on the recording side in FIG. 1,
3 is a diagram showing an example of the configuration of the light receiving section of the glass fiber 1 in FIG. 2, FIG. In the example, the light source is 8
Figure 6 is a diagram showing the configuration when 240 of the same light sources are provided, Figure 7 is a diagram showing still another embodiment on the recording side, and Figure 8 is recording optical signals on tape. FIGS. 9 and 10 are diagrams showing the configuration of the light exit portion in this case, and FIGS. 9 and 10 are diagrams showing the specific configuration of the detector disposed on the reproduction side. 1...Light source, 2...Light distributor, 3...
...Electrical signal-optical signal converter, 5... Analog-digital converter, 6... Optical switch, 9
. . . Tape-shaped recording medium, 10 . . . Detector, 11 .

Claims (1)

[Claims] 1. Sample the signal to be recorded, convert it into an m-bit digital signal, convert this signal into an N-channel optical signal that is an integral multiple of m, and convert this N-channel optical signal into an optical signal. Through an N-channel optical transmission system, each channel m or an integer multiple of m is transmitted to an N-channel optical transmission system whose tips are arranged on a tape-shaped recording medium in a direction that crosses the running direction of the tape-shaped recording medium. An optical multi-channel recording method, characterized in that optical signals of channels are recorded on the tape-shaped recording medium in a direction crossing the running direction of the tape-shaped recording medium. 2. When converting an m-bit digital signal into an N-channel optical signal, the luminous flux from one light source such as a laser is divided into m channels, and the resulting m luminous fluxes each correspond to each bit of the digital signal. m optical modulators to obtain m optical signals corresponding to each bit of the digital signal, and these m optical signals to n optical switches satisfying m×n=N. 2. The optical multi-channel recording method according to claim 1, wherein the optical signals of m channels are sequentially obtained from the optical switching device in synchronization with sampling. 3. Claim 2, characterized in that optical fibers are used as the optical transmission system from the light source to the optical modulator, from the optical modulator to the optical switch, and from the optical switch to the recording medium. optical multichannel recording method. 4. When guiding optical signals from m optical modulators to n optical switches, simultaneously deflect the m optical signals into n stages in synchronization with sampling and guide them to the n optical switches. An optical multi-channel recording method according to claim 2, characterized in that: 5. The light-receiving area of the m light introduction ends of each of the n optical switching devices is made larger than the cross-sectional area of the optical transmission medium that guides the light onto the recording medium, making it possible to absorb minute errors in optical deflection. An optical multi-channel recording method according to claim 4. 6. The optical multi-channel recording method according to claim 5, wherein a convex lens-shaped photoconductor is provided at each of the m light introduction ends of the optical switch to improve light introduction efficiency. 7. In converting an m-bit digital signal into an N-channel optical signal, m independent light sources are formed, and the amount of light emitted by each light source is controlled by the m-bit digital signal. The m optical signals are respectively guided to n optical switching devices satisfying m×n=N, and the optical signals of m channels are sequentially transmitted from the optical switching devices in synchronization with sampling. 2. An optical multi-channel recording method according to claim 1, characterized in that: 8. To convert an m-bit digital signal into an N-channel optical signal, the light from N light sources is modulated by the digital signal, or the amount of light emitted from M light sources is modulated by the digital signal. 2. The optical multi-channel recording method according to claim 1, wherein N-channel optical signals are obtained by controlling. 9 N optical modulators or light sources whose emission amount can be controlled,
Optical multi-channel recording according to claim 8, characterized in that m or m×K (K is an integer and m×K is an integer fraction of N) pieces are simultaneously modulated or controlled at a sampling period. Method. 10. According to claim 9, the digital signal is stored in an m×K bit memory, and as many optical modulators or light sources whose light emission amount can be controlled are simultaneously driven as many as the number of bits in the memory. Optical multichannel recording method. 11 Sample the signal to be recorded, convert it into an m-bit digital signal, convert this signal into an optical signal that is an integral multiple of m, and send this N-channel optical signal to m or m through an optical N-channel transmission system. The optical signals of N channels are transmitted on a tape-shaped recording medium in a direction that crosses the running direction of the tape-shaped recording medium, and during playback, the recorded signals of only m or channels that are an integral multiple of m are transmitted. 1. An optical multi-channel recording and reproducing method characterized in that reading light is simultaneously irradiated onto the top of the recording medium, corresponding signals are read out by N-channel photodetectors, and the original signals are reproduced through circuit processing. 12 Detecting elements of an N-channel photodetector are arranged on a recording medium in a line in the direction in which signals are recorded, and the information of m or an integral multiple of m channels recorded at the same time is detected by the movement of the recording medium. 12. The optical multi-channel recording and reproducing method according to claim 11, wherein the optical multi-channel recording and reproducing method is characterized in that reading is performed by sequentially shifting in a direction crossing the traveling direction. 13 The detection elements of the N-channel photodetector are arranged in rows of m or integral multiples of m, shifted in the running direction of the recording medium, so that the recorded N-channel information corresponds to the N detection elements. Claim 1, characterized in that the original signal is reproduced by simultaneously irradiating all N channel information with reading light when the signal reaches the position, storing the N channel information in a memory, and sequentially reading it out. 12. The optical multi-channel recording and reproducing method according to item 11.