JPS60229276A - Synchronization for optical recording and reproducing of digital information - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a system for storing and reproducing digital information at an extremely high density, and in particular to optically recording an electrical human input signal as a single track consisting of digital information spots; The present invention relates to a method for optically reproducing recorded digital information.

The outline of the method of the present invention is as follows. That is, the recording section of the apparatus according to the method of the present invention first converts an analog human input signal into a digital electric signal, thereby generating a single pulse, and scans a photosensitive plate using a pulse group of the digital signal to generate a digital code. The information is recorded continuously on a photosensitive plate as a single track consisting of a group array of information spots. The reproducing section of the apparatus according to the method of the present invention uses a photocell to optically scan the optically recorded digital recording signal to form a digital readout electrical signal, and converts this digital readout signal into an analog output signal that is the same as an analog input signal. and play it.

Although the device according to the method of the invention is particularly suitable for recording and reproducing audiovisual signals, such as electrical analogue signals, such as television video signals, high-fidelity music signals, etc., the method according to the invention provides information recording and reproducing devices such as electronic computers used for data processing purposes,
It is also possible to constitute a main part of a character reading device or a photo inspection device, and to take an input signal as an optical signal, convert it into a digital electrical signal, optically record it, and reproduce it.

Conventionally, a device for optically recording and reproducing audible signals using a light beam has not been put to practical use. As one of the conventionally considered devices, J. Rabinow
Some, as described in U.S. Pat. No. 3,138,669 to Daichi, used light beams and photocells to simply reproduce the light reflected from the grooves of ordinary audio records. More recently, Mr. Nie Schomer (11
It has been proposed, as described in U.S. Pat. There is. but,
In these known systems, a kind of analog signal is recorded rather than a digital signal, so that the amount of information recorded and the quality of the signal produced during playback is limited to a very low quality. In contrast, in the present invention, the analog signal is converted into a digital signal before being optically recorded, and this is recorded as a trajectory of a light spot on the photoreceptor, so the above-mentioned drawbacks are completely eliminated. Ru.

In addition, Mr. R.K.Botter (R.K., Potts)
A known apparatus records digitally encoded information on photographic film using pulse code modulation, as described in U.S. Pat.
It has been proposed to improve the transmission quality of voice signals on telephone lines by reproducing this.

However, since the known methods use a large number of light sources and selectively energize these sources using an electronic switching device configured as a cathode ray tube, the resulting photographs can only tolerate very low information densities; This required the use of a moving film strip as the recording medium. In the present invention, a single pulse light source is used, for example, 17300 mI11
A very small focus, such as the diameter of
Since it records a trajectory of light spots with an extremely high density of about 5.times.10' bits per square inch, it does not suffer from the above-mentioned drawbacks.

Reading out optically recorded information requires proper synchronization to reorganize the information into the originally recorded "words", each of these "words" representing a specific number. represent continuous components of an audio signal or other analog signal. Synchronization can be accomplished in a variety of ways by physically separating the recorded information into word groups. However, conventional word group separation term synchronization bit formats have the drawback of reducing the information density required for photographic recording.

In devices according to the method of the invention, novel markings are used for synchronization purposes, but as the information density increases, the identification of synchronization signals may become difficult.

Therefore, in the method of the present invention, various embodiments are provided regarding methods for solving this problem.

The information recording and reproducing apparatus according to the method of the present invention has the following advantages over conventional apparatuses. That is, the device according to the method of the present invention is much cheaper than the known video signal recording and reproducing device using magnetic tape, and since the method of the present invention forms a record as a photograph, high-quality copies can be reproduced at low cost. and has a much longer lifespan than magnetic tape or traditional audio records. Furthermore, according to this digital encoded photo recording device, a large amount of information can be recorded in a smaller space than conventional ones. Furthermore, if an information photographic recording device using digital optical signals is used, the signal-to-noise ratio will be much higher when reproducing analog input signals.
Playback quality can be improved. Furthermore, according to the method of the present invention, high quality can be expected because the output signal quality is less affected by the frequency response of the recording medium or the recording/reproducing device. Further, according to the photographic recording apparatus according to the method of the present invention, since a photographic record can be formed on a flat plate, automatic performance is possible like an automatic record playing apparatus of a photographic slide projector or a record player.

It is an object of the present invention to provide an improved recording and reproducing method for optically recording and reproducing digitally encoded electrical signals with extremely high information density on a photosensitive medium.

In addition, the method of the present invention converts an analog input signal into a digitally encoded electrical signal, records this type of digital signal photographically using a pulsed light source with an extremely small focus, and optically records this recorded photograph using a photodetector. It is an object of the present invention to provide a method for forming a digitally encoded readout electrical signal by scanning and converting this signal into an analog output signal to obtain an analog output signal with a high S/N ratio and high reproduction quality.

Another object of the method of the present invention is to provide a recording method for recording digitally encoded electrical signals on a photosensitive medium as a single track consisting of a series of trajectories of light spots having extremely small dimensions and having an extremely high density per unit area. It is on offer.

The method of the present invention also uses an optical scanning device with a rotating mirror that is electrically deflected in a radial direction and operated by centrifugal force to form a helical scanning pattern, thereby scanning a flat photographic plate. It is an object of the present invention to provide an optical scanning method that enables the length of the optical path to be maintained approximately constant at all times during scanning.

An additional object of the method of the present invention is to optically scan a photo of the trajectory of a digitally encoded light spot using a photodetector, read out an electrical digital signal inexpensively and accurately, and reproduce the signal. is to obtain.

Furthermore, the method of the present invention uses a photographic recording element that records the locus of digitally encoded light spots on the recording medium at an extremely high density in order to form a record that is inexpensive, compact, long-life, and can be easily made into high-quality copies. The purpose is to obtain.

Another object of the method of the present invention is to provide an improved method for recording and reproducing information which makes it possible to store digital information at high density on a photographic record and to obtain read synchronization.

Furthermore, the method of the present invention adds word synchronization focus to digital bits of digital data representing information, and makes the shape of the word synchronization bits approximately equal in size to the digital bits and different in shape from the digital bits. A word synchronization signal is generated by a series of word synchronization bits that are recorded at different recording positions and read out during playback, and the recorded information is read out for each data word using this inter-word 'M signal. To provide an improved synchronization method for optical recording and reproduction of digital information in which the recording density does not deteriorate significantly even when a synchronization bit is newly inserted.

Still further, the method according to the invention is particularly advantageous when it is possible to replace digital bits at predetermined positions within a word representing information with word synchronization bits that differ in shape.
In particular, no extra space is required for adding word synchronization bits, and the recording density is further improved.

The device according to the synchronization method for recording and reproducing information according to the invention shown in FIG. 1 has a recording section 10, the input of which is connected to an audible and visible analog signal source 12, such as a microphone or a television camera. The device also includes a playback section 14,
Its output is connected to an analog signal utilizing device 16, such as a loudspeaker, television receiver, cathode ray oscillograph, mechanical recording device, or the like. 18 is a suitable photocopying device;
For example, one digitally encoded master photograph 2 created by the recording unit 10 is capable of contact printing.
0 can be inexpensively copied, thereby creating a large number of digitally encoded photocopies 22, which are used as manual information for the reproduction section 14. In this regard, the apparatus according to the method of the present invention is based on the same idea as that of a record production apparatus that produces a large number of copy records from one master record and sells such copy records to consumers at a relatively low cost. There is.

Signal source 12 generates an audible and visible analog signal 23.

, this signal may be an audible signal such as a high fidelity music signal or a television video signal. This analog input signal is fed to the input of an analog-to-digital converter (A-D converter) 24 of the recording section IO, thereby forming a digitally encoded electrical output signal 26.

However, it is also possible to replace the signal source 12 and converter 24 with devices for converting analog optical input signals into digital electrical output signals, such as those used in character reading devices or aerial photo analysis devices. This digital signal 26 is a known pulse code modulation (PCM)
is formed by pulses or words representing the instantaneous amplitude of each portion of the analog input signal 23. If you want to record digital signals in real time, use the ^-0 converter 24.
to an electro-optical digital signal recorder 28,
It is sufficient to connect directly through the amplifier 29. However, this digital signal 26 is
It is preferable to store such signals temporarily on magnetic tape at a later time at a convenient time.

Therefore, in the illustrated embodiment, signal converter 24 and amplifier 29
Although a digital computer 30 is shown connected between the two, the apparatus according to the method of the present invention is not limited to this.

An electro-optical digital signal recorder 28 converts the digital electrical signal into a digital optical signal and scans the photosensitive element with a pulsed beam of light having an extremely small focus of 0.01 mm in diameter.
This type of optical signal is photographically recorded by forming a trajectory of digitally encoded light spots (m+11 or less). If a binary digital signal is used, this spot may be opaque or transparent, forming the 0 and l bits of the binary code. However, the present invention is not limited thereto, and other digitally encoded signals can also be used. For example, a ternary digital code with transparent, partially transparent and opaque dots on black and white photographic film may be used.

The reproduction section 14 comprises an optical-electrical digital signal reproduction device 32, by means of which the digitally encoded photocopy 22 is reproduced.
The photocell is scanned through to produce a digital electrical output signal 34 corresponding to a digitally encoded picture of the light spot. That is, the digital electrical output signal 34 is transmitted to the recorder 2.
It corresponds to the digital input signal 26 provided on the day. Although the reproduction device 32 is shown as a separate device from the optical recorder 28, they can use the same optical scanning device by simply replacing the pulsed light source and photocell of the recorder. The playback device 32 connects it to a D-^ converter 38 via an electrical readout circuit 36 having a shift register;
A device 1 that uses the output of the signal converter 38 via an amplifier 40
6 and supplies the utilization device 16 with an analog signal 42 corresponding to the digital signal 34 formed by the signal converter. This analog output signal 42 is thus a high-quality reproduction signal of the analog input signal 23, and this output signal has extremely low distortion (high signal-to-noise ratio). This density is achieved because the particle size and optical non-linearity of the photosensitive material do not limit the recording information density of digital signals as it does when recording analog signals using this type of photosensitive material. It is something.

FIG. 2 shows an embodiment of the apparatus according to the synchronization method for recording and reproducing of the present invention shown in FIG. By simply moving either the recording light source 46 or the photocell 48 with respect to the split mirror 50 to be on a straight line with the mirror 50, it can be used for both recording and reproduction. Recording light source 46
is a single light source with high intensity and small size, such as an arc lamp or a laser. Further, behind the digitally encoded photocopy 22, a large area reproduction light source 52, such as an array of fluorescent lights, is disposed and is selectively connected to a power source 56 by a switch 54 to be energized. Although the power source 56 is shown as a battery to simplify the illustration,
Configured with an optional DC power source connected in the "play" position of switch 54. Although in the illustrated embodiment the reproduction light source 52 is configured to transmit light from the back of the digitally encoded photocopy 22, the light source is placed in front of the copy and outside the scanning light beam, e.g., surrounding the copy. Like a circular fluorescent light (reflected light can also be used if placed).

When switch 54 is placed in the "record" position, recording light source 46 is energized to enable recording of digital information.

This light source is moved in the direction shown by the arrow 58 and the photocell 48
In order to move to the position, the container 60 containing the light source and the photocell should be moved downward.

Although the light source 46 can also be directly supplied with a digitally encoded input signal formed by the signal converter 24 of the recording section 10, in the example shown this signal is supplied to an electronic shutter 62 arranged in front of the light source, A light pulse beam was formed. The shutter 62 may be a car cell containing a nitrohenzene solution or a series of crystals of potassium dihydrogen phosphate. Such a Kerr cell or crystal has electrical birefringence properties. Shutter 62 connects it to the output of amplifier 29 via a two-way switch 64 , which connects it to the output of amplifier 29 .
4 is interlocked with the switch 54, so that the switch 64 is turned off in the "playback" position, and the switch 64 is turned on in the "record" position. This light source 46 makes it possible to form a continuously operating parallel monochromatic light beam of extremely high intensity.

Optical scanning device 44 is rotatably mounted on shaft 70 and includes a circular support plate 66 made of aluminum or other non-magnetic material having an axially extending recess 68 . A belt 76 and a magnetic clutch 74 are connected to the shaft 70, and the shaft 70 is rotated about a vertical shaft at a constant speed by a motor 72.

A leaf spring 80 is attached to one edge of the support plate 66 by screws 82 or other suitable means, and a flat mirror element 78 is mounted at its upper intermediate portion. leaf spring 8
0 is fixed by a guide slot 84 provided on the upper side of plate 66 and extends to intersect the axis of rotation of shaft 70 so that the center of scanning mirror 78 is approximately centered on this axis of rotation. A solenoid element 86 of magnetic material is provided on the underside of the mirror 78 on the back side of the spring 80 and is arranged to be inserted into the recess 68 in the plate 66 when the spring is pulled down. Both the recess 68 and the solenoid element 86 are frustoconical. An electromagnetic coil 88 is placed near the bottom of the recess 68 surrounding the axis of the rotary plate 66 such that the magnetic field to this coil attracts or pushes the solenoid element 86 into the recess, thereby causing the spring 8
0 can be deflected and scanned over digital encoded photocopy 22 by means of mirror 78.

Furthermore, a weight 9o is attached to the free end of the spring 80 so that when the rotational speed of the support plate 66 increases, the spring is pushed downward by the centrifugal force of the weight.

In order to damp the vibrations of the spring 80, a permanent magnet 92 with a slot is attached to the 1- side surface of the rotating plate 66.
Furthermore, a conductive thin blade 194 is attached to the end of the weight 90, and this is placed in the slot 96, and this blade 94 moves up and down between the two poles of the slot on the permanent magnet g2, thereby preventing vibration. It generates eddy currents and attenuates them. Instead of such a permanent magnet damper, it is also possible to use an oil damper in which the recess is filled with oil and the solenoid element 86 moves within the dashpot.

As previously mentioned, the beam splitting mirror 50 and the axis of rotation of the shaft 70 and the photocell 48 or light source 46,6
The optical path between the perforated masks 98 disposed on the front surface of the mask 2 is arranged so as to form an angle of 45° with respect to both of the optical paths. This split mirror 50 transmits approximately 50% of the incident light and reflects approximately 50% of the incident light. A spherical mirror 100 is placed between the split mirror 50 and the center of the photographic element 22. A magnifying glass 102 is further placed between the mask 98 and the beam splitting mirror 50 to direct the light source to a very small diameter spot on the photographic element 22 and to view the field of such a small spot. Try to limit your field of view. This magnifying glass can also be omitted. Furthermore, an objective lens may be provided between the magnifying glass 102 and the beam splitting mirror 50. In this case, the spherical mirror 1
00 can be omitted, and the beam splitting mirror is then rotated by 90°.

During recording operation of the apparatus shown in FIG. 2, the light source case 60 is moved downwardly to a lower position so that the light source 46 is in line with the opening in the mask 98. Additionally, switch 54 is moved to the "record" position to energize this light source and turn off playback light source 52.

In this case, the switch 64 is moved to the recording position "R" and the electronic shutter 62 is connected to the ^-D converter 24 so that the digitally encoded pulses are supplied to the encoder 62 via the amplifier 29 and a number of Generates a light pulse. This digitally encoded light pulse is transmitted to a beam splitting mirror 50, where approximately 50% of the light is reflected off a spherical mirror 100, which refocuses it onto the mirror 50, and finally 25% of the light passes through the splitting mirror 50. The light reaches scanning mirror 78. These light pulses are then reflected by a scanning mirror 78, in this case the photographic copy 2 shown.
The image is projected onto a master photographic photosensitive plate 20 arranged in place of 2. Further, by setting the switch 104 to the "record" position, the magnetic clutch 74 is connected to the movable contact of the potentiometer 106 whose both ends are connected between the positive DC power source and the ground, and the motor 72 causes the scanning mirror 7 to move around the shaft 70.
Rotate 8. For example, the motor 108 automatically controls the movable contacts of the potentiometer 106 to gradually increase the rotational speed as the light beam moves radially inward of the photosensitive element. This radial movement of the scanning beam is accomplished by connecting the electromagnetic coil 88 to the movable contact of another potentiometer 110 with the switch 112 in the "R" position, and connecting both terminals of this potentiometer to the positive D.
This can be done by connecting between the C power source and ground. The movable contact of this potentiometer 110 is also connected to the motor 1.
08 and gradually increases the current flowing through the coil 88 to gradually deflect the mirror 78 in the radial inward direction. Furthermore, the scanning mirror is deflected radially inward by centrifugal force as the rotational speed of the weight 90 increases. The optical scanning device 44 thereby scans in a helical manner over the photosensitive element and records the light pulses as a trajectory of digitally encoded light spots with successive points spaced apart on each trunk.

Such records are shown in FIGS. 5 and 5A. Potentiometers 106 and 110 are required to provide very smoothly available control voltages to the magnetic clutch and deflection electromagnetic coils, for which wire-wound potentiometers are inadequate and continuous resistance layer potentiometers are used.

Further, the resistance of these potentiometers may be changed non-linearly.

To perform playback using the apparatus shown in FIG.
Further, the switch 64 is set to the playback position "P" to cut off the shutter 62 from the amplifier 29, the light source container 60 is moved to the upper position shown in the figure, and the photocell 48 is opened in the opening provided in the mask 98. Switches 104 and 112 are also in the "play" position shown.The light image of the spot on photocopy 22 is then reflected by scanning mirror 78 and beam splitter mirror 78. 50 to a spherical mirror lOO, and is reflected again by this spherical mirror 100 to focus the image on a beam splitting mirror 50. This beam splitting mirror reflects the light again and directs the light to the photocell 4 via a magnifying mirror 102.
Let light be incident on 8. Photocell 48 converts these light pulses into digitally encoded electrical pulses that produce an output current in a load resistor 114 connected between the anode of photocell 48 and ground. The digital voltage pulse thus generated across the terminals of the resistor 114 is read out by the readout circuit 36.
and further to the deflection control circuit.

The deflection control circuit has an operational amplifier 116 and an amplifier 1
16 is a oscillator 120 whose operation will be explained below.
Frequency #! ! , ([1)]. The input of operational amplifier 116 connects it to photocell 48 via a combiner 122, the output of the amplifier connects it to one output of phase comparator 124, and the other input of said phase comparator 124 connects it to photocell 48. Connect the output of oscillator 120.

The analog output signal of the phase comparator 124 is transferred to the integrating circuit 126.
This is supplied to one input of the adder circuit 128 via a coupling resistor 130, and the output of the tracking oscillator 120 is supplied to the other input via a coupling resistor 130. The output of summing circuit 128 connects it through amplifier 132 and switch 112 to regenerative feedback middle gag magnet coil 88 . As the average amplitude of the digital pulses transferred from the tuned feedback circuit to the integrator 126 and integrated changes as the scanning mirror 78 moves over the trunk, the output voltage of the integrator 126 changes accordingly, causing the electromagnetic A control voltage applied to coil 88 is varied, thereby deflecting scanning mirror 78 radially inward so that mirror 78 follows the trunk.

The rotational speed of device mirror 78 is controlled by the output signal of differential amplifier 134, which output signal is applied to switch 10.
4 to the magnetic clutch 74 in the "regeneration" position. The power of differential amplifier 134 connects it to the movable contacts of potentiometer 136, connecting both terminals of the potentiometer between a positive DC power source and ground. The other input terminal of the differential amplifier 134 is also connected to an integrating M capacitor 138 whose terminals connect them between a coupling diode 140 and ground.

The anode of the diode 140 connects it to the output of a synchronization bit detector 142, which forms part of the output circuit 36.
8 to generate a synchronization output pulse when a synchronization pulse is present in the output signal of the photocell.

The synchronization pulse has, for example, a larger amplitude than the digital encoding pulse. These synchronized pulses are connected to capacitor 138
The changing voltage of the output is integrated by the differential amplifier 13.
4 as a control voltage. Thus, scanning mirror 7
As 8 is deflected radially inward, the rotational speed of shaft 70 increases, keeping the synchronous focusing speed at a constant value.

These synchronization pulses are generated by synchronization dots recorded on the photocopy 22 between each digitally encoded dot group or word to separate them.

Conventionally, these synchronized light spots have a diameter approximately twice that of the digitally encoded light spots, and they supply a large voltage pulse to the electronic shutter 62, allowing a large amount of light to pass through the shutter. Record.

In order to properly direct scanning mirror 78 onto the helical trajectory of the light spot of storage element 22, tracking oscillator 120 generates a small amplitude sinusoidal tracking signal and superimposes it on the deflection control signal provided to coil 88. Configure it like this. This tracking signal causes the scanning mirror to oscillate back and forth across the track with a low frequency f1, such as about one cycle per 100 words or 30-70 oscillations per revolution. This generates a correction signal, which is transmitted to the photocell 48.
This correction signal filters the bit current pulses by capacitor 122 and amplifiers 116, 118 to form a correction signal at extraction frequency 2f. This frequency is equal to twice the frequency of the tracking oscillator 120 because the scanning mirror traverses one track twice in each sinusoidal cycle of the tracking oscillator output signal.

This corrected signal is compared in phase comparator 124 with the output signal of the tracking oscillator, and when these two signals are not in phase, it indicates that the mirror has begun to fall off the trunk and automatically changes the output voltage of integrator 126. to place the scanning mirror back on the trunk.

Readout circuit 36 includes a bistable multivibrator 144 whose input is connected to the input of sync bit detector 142 as well as to the output of photocell 48 . The bistable multivibrator can be of the Schmitt trigger type, with the bistable multivibrator being triggered on the leading edge of each digital pulse and also inverted on the trailing edge to create a rectangular output pulse, which output pulse is shifted. Transfer to register 146. The input of the free-running bit clock pulse generator 148 is connected to the output of the sync bit detector 142 to synchronize the bit clock with the sync pulse. The output of bit clock pulse generator 148 connects it to shift register 146 to provide shift pulses thereto, causing the shift register to shift at the same frequency as the digital code signal produced by photocell 48. Once digital pulses or "words" are received in shift register 146, these digital pulses are transferred to storage register 150 via transfer gate 52. This transfer gate 52 is normally non-conducting and is driven into a conductive state by a word sync pulse applied to the transfer gate from the sync bit detector 142. The output of the storage register 150 connects it to the input of a digital-to-analog converter (D-^ converter) 38, which converts a digital signal input to an analog output, and such analog output signal is passed through an amplifier 40 to the apparatus. is transmitted to the output terminal of As previously mentioned, the analog output signal is an accurate binocular version of the analog human input signal provided to transducer 24.

Another embodiment of the apparatus according to the recording/reproducing synchronization method of the present invention is shown in FIGS. 3 and 4. Optical scanning device W4 used in this example
4' has a polygonal mirror 154 with twelve flat mirror surfaces 156 around the axis of rotation 158 of said polygonal mirror.
Divide and arrange evenly. Polygonal mirror 154 is continuously rotated approximately horizontally about a vertical axis 158 by a drive mechanism 160 that couples the mirror to an electric motor 162 . Further, a vibration drive mechanism 166 that connects the mirror to the motor 162 via a magnetic clutch and reduction gearing 170 is used to cause the polygonal mirror 154 to vibrate approximately vertically about a horizontal axis 164 . Photo copy 2 of the flat image field correction plate 172 in the shape of a concave lens.
2'' to compensate for variations in scanning distance between the mirror piece 156 and the photocopy during scanning. That is, the portion of the corrector plate adjacent the outer edge is made thicker to compensate for the longer scanning distance between the mirror piece and the outer edge of the photocopy 22'.

A beam splitting mirror 174 is arranged between the field correction plate 172 and the polygonal mirror 154, and another mirror 176 is arranged in the optical path between the beam splitting mirror 174 and the magnifying mirror 1020.
to be placed. Also, instead of the spherical mirror lOO in the example of FIG. 2, an objective lens 178 is placed between the mirror 176 and the magnifying glass to focus.

During recording, the apparatuses shown in FIGS. 3 and 4 operate in the same way as the apparatus shown in FIG. The difference is that magnetic clutch 168 is connected to the movable contact of potentiometer 180 via the "record" position of switch 182, and both terminals of said potentiometer are connected between a positive DC voltage source and ground. Connect to.

Here, by setting the movable contact of the potentiometer 180 to a certain fixed value, the vertical scanning speed during recording can be determined. Furthermore, the switches 54 and 64 are moved to the recording position "R" to cut off the reproduction light source 52 from the power supply 56, and the recording light source 46' is connected to the output of the A-D converter 24 via the amplifier 29. Pulse light source 46' should be capable of producing gas discharge strobe light or other pulsed light with extremely high frequency response similar to those used in photography.

To perform playback with the apparatus shown in FIGS. 3 and 4, the second
The apparatus is substantially similar to the one shown, but a pair of photocells 184 and 186 are arranged with the openings of the corresponding mask 98' in a straight line, so that the field of view of the photocells follows the track of the light spot recorded on the photocopy 22'. be located on both sides. The anodes of photocells 184 and 186 are each connected to an amplifier 188.
and 190, these are connected to respective inputs of an adder circuit 192, the output of which is connected to the input of the bistable multi-high break, and further connected to the synchronous focus detection circuit of the continuation circuit 36 in FIG. The outputs of amplifiers 188 and +90 are connected to respective inputs of differential amplifier 194 through coupling resistors 196 and 198 and integrating capacitors 200 and 202, respectively.

Also, the output of the differential amplifier 194 is connected to the output of the switch 182.
Connect to the magnetic flannel 168 through the ``playback'' position and supply it with a control voltage signal, thereby adjusting the vertical speed of the polygon mirror so that the field of view of detectors 184 and 186 is located on both sides of the trunk. In this way, when the scanning mirror piece 156 goes off track during playback, a disparity occurs between the output signals of the detectors 184 and 186, causing a difference in the output of the differential amplifier 194. Forming a signal, which corrects the vertical error of the mirror strips and correctly points the mirror on the track.Differential amplifier 1
When the input signals of 94 are equal to each other, the differential amplifier 1
By making the DC output voltage of 94 equal to the voltage of the movable contact of potentiometer 180, vertical vibration drive mechanism 166 can move the polygonal mirror vertically at the same speed as during recording, and the output of differential amplifier 194 Its DC output voltage can be adjusted by a connected variable load resistor 204. As shown in FIG. 5, the canine recording element photographic copy 22 produced by the apparatus of FIG. 2 has a helical trunk 206 of digitally encoded light spots. This trunk consists of an opaque point 208 formed by a light pulse corresponding to a "1" bit of a binary digital code and a "1" bit of that code.
is formed by a transparent spot 210 corresponding to a 0" bit. Spots 208 and 210 are each approximately 0.01n
It is possible to have a diameter of less than u@, especially about 1/300 m+m. Furthermore, synchronization spots 212 are provided between successive digital bit groups or words. In the example of FIG. 5A with conventional word synchronization spots, the code group or "word" consists of 15 bits, and the top track in FIG. 5A consists of 8 transparent points and 7 opaque points. . The sync spot 212 is about twice the diameter of the opaque spot 208, and the distance between the centers of the spots on adjacent lines is about twice the diameter of the opaque sub-spot 208, so if the sync spots are adjacent, they will be mutually exclusive. It will be in contact with. Third
The rectangular raster of tracks 214 of digital code spots recorded by the apparatus shown in FIGS. Continuous vertical movement of polygonal scanning mirror 154 causes each of these adjacent tracks to tilt diagonally downward. Each adjacent track is scanned by an adjacent mirror piece of the polygon mirror so that the tail end of the leading line coincides with the leading edge of the trailing line.

The size and spacing of the digitally encoded opaque and transparent spots 208 and 210 shown in FIG. 68 are the same as in FIG. 58. The word synchronization spot in FIG. 68 is also the same conventional word synchronization spot as that in FIG. 5A. When the photosensitive recording elements 22 and 22' are used for reproduction and transmit light from a light source as shown in FIG. do. However, if light reflection photography is used, the recording elements 22 and 22' should be constructed of a suitable dimensionally stable support material, such as plastic, and the recording elements 22 and 22' should be constructed of a suitable dimensionally stable support material, such as plastic, with a photographic record having a digitally encoded trunk on its outer surface. Paste and use. A plastic protective coating may be provided over the top surface of such photographs and over the photosensitive coating on the transparent plate to protect them from damage during handling. Furthermore, it is also possible to use photosensitive glass without a separate layer of photographic material; such glass requires etching after exposure of the digital code trunk to light. in this case,
The etched spot is filled with a material that does not transmit light. Furthermore, it is also possible to use photochromic materials instead.

Furthermore, the reproduction record can be produced by mechanical means, such as printing or embossing, or by thermal means, such as thermoplastic deposition techniques. The playback record can also be produced by chemical etching using photoresist technology, for example as described above in relation to glass, and it is also possible to use this for other materials of the photoresist type.

An important aspect of this method is, for example, the problem of bit synchronization of the bit clock 148 in FIG.

Details of a bit clock circuit for a device according to this method are shown in FIG. In the figure, a lead 220 receives raw data from a second illustrated photocell 48, which is coupled as an input to an amplifier/clipper circuit 222 and an analog gate 224. The waveform of the original data manually is shown as 226 as an example. This data input is shaped by an amplifier and clipper circuit to derive waveform 228. Differentiator circuit 230 provides a bit clock synchronization pulse output 232 for use by a synchronization oscillator 234. The synchronous oscillator 234 may be of a free-running multi-high break type, and can be synchronized by the pulse waveform 232. The nominal operating frequency of oscillator 234 is selected to be approximately the same as the data repetition rate to produce an output pulse train as shown at 226. This pulse train is transmitted to the delay circuit 238
This is supplied to the pulse shaping circuit 240 via the circuit 2
40 to derive a "bit clock" output for operating analog gate 224.

The delayed "bit clock" output thus starts slightly later than the leading edge of the original data pulse, and is
The output of analog gate 224 is gated by a "bit clock" output having a waveform derived from an oscillator and includes a regenerated input signal as shown at 242.Threshold circuit 2
The pulse input 24 is properly shaped to remove the partial output at 24 and feed into the second illustrated shift register 14G.
Supply 6.

An embodiment of the word synchronization bit according to the present invention uses a recorded word synchronization spot like the conventional example shown in FIGS. 5a and 6a, but in this case, instead of increasing the size of the spot, the shape of the synchronization spot is is changing. In FIG. 8, 318, 320 and 322 indicate portions of three tracks. For track 318, the word sync spot is hourglass-shaped, and for track 320, it is triangular. Also, for trunk 322, the word sync spots are diamond-shaped and boat-shaped, with a central portion having approximately the same dimensions as the information bit spots. Word synchronization spots of different dimensions can be distinguished using optical means. In FIG. 9, when light from a focusing lens, mirror, etc. is directed toward a beam splitting mirror 324, the light not only travels straight toward a mask 326, but also travels straight toward a second mask 328. Recording spots (not shown) are imaged sequentially through the same optical path onto masks 326 and 328. Details of masks 326 and 328 are shown in FIGS. 1O and 11. The image of the circular data box 7) is a mask 32
6 to activate a detector 332, shown in FIG. 9, having a suitably placed photocell. However, the data spot does not provide light to activate the same detector 334 through the end opening 336 of the mask 328 for the word sync spot. When a word sync spot having the shape of track 322 of FIG.
detected and both detectors are activated. If the light has a predetermined minimum intensity, the threshold circuit 338
and 340 provide its output to AND gate 342.

The output of the All 342 is provided as a word sync and serves as the sync bit detector 142 of FIG.

In this embodiment, transparent spots placed on an opaque background are considered, but opaque spots can also be used.

Trunk offsets can also be used for word synchronization. In the case of this second embodiment, the synchronization spot is a data display spot as shown in FIG.

The synchronization spot is shifted from the center by an amount corresponding to about 10 to 20% of the interval between the trunks. For example, when a tracking system such as the two-detector type shown in Fig. 3 is placed at the rear, sudden short bursts due to synchronization spots may occur.
Error” indication can be separated from normal slow drift.

FIG. 13 shows details of the circuit. In the figure, circuit elements 188, 190, and 192 are the same as the circuit elements with the same numbers shown in FIG. Amplifiers 188 and 19
The output of 0 is sent to the integrating circuit 196 shown in FIG. 3 for tracking purposes.
200 and 198.202, but also feed their outputs to an additional differential amplifier 344 shown in FIG. The output of the differential amplifier is differentiated using a circuit including a capacitor 346 and a resistor 348 with one end grounded, and this differentiated signal is supplied to a pulse shaping circuit 350. A slowly drifting tracking error, when differentiated, will produce insufficient output to activate the pulse shaping circuit 350, but a sudden short "error" for word synchronization purposes as shown in FIG. An input spike to shaping circuit 350 is provided to activate pulse shaping circuit 350 and provide word synchronization.

14 and 15 show the word synchronization method cylinder 3 according to the present invention.
and other examples. In the figure, a photosensitive recording medium 352 includes a plurality of photosensitive layers 354 separated by a photoinsensitive material. In order to form a spot on a specific photosensitive layer, the spot can be formed on the surface of the photosensitive layer.

The spacing between the photosensitive layers is greater than the depth of focus of the recording optical system used, so that each layer can be recorded individually or sequentially. Multiple light sources or multiple detectors can also be used for recording and reading. It is also possible to appropriately shift the focal point when using a single light source or a single detector. The word synchronization spots are suitably located in separate photosensitive layers belonging to separate focal planes and distinct from data bits.

FIG. 15 shows a device for transmitting information using optical beams t. In this case, the light beam is directed towards a perforated mask 356 with data bit-shaped openings located in front of a detector 358 with a photocell. The image corresponding to the data bit recorded as a spot on one of the photosensitive layers is mask 3
56 and activates the detector 358. Also,
The light passes through beam splitting mirrors 360 and 362. These mirrors are connected to detectors 368 and 370, respectively.
The light is directed toward masks 364 and 366 located in front of the. Since the distance from the photosensitive layer object spot (not shown in FIG. 15) is the same for each mask, images of individual photosensitive layer spots are formed in separate planes of the associated mask.

It is also possible to use one of the detectors in combination with an associated photosensitive layer for synchronization purposes, while the other detector and associated photosensitive layer can be used for other information, such as audio stereo etc. .

In another word synchronization bit embodiment according to the invention, the spots on the various different photosensitive layers as shown in FIG.
Mask associated color filters 356, 364 and 366
This can be recorded in various colors by placing it at a location. In this case, recorded data of different colors do not need to be separated in separate photosensitive layers, but can be distinguished solely by color, and one of such colors can also be used for synchronization purposes. .

[Brief explanation of drawings]

Fig. 1 is a block diagram of an apparatus according to the method of the present invention, and Fig. 2 is a block diagram of a part of the apparatus according to the method of the present invention shown in Fig. 1 using optical scanning with a magnetic deflection rotating mirror. FIG. 3 is a diagram showing the main part of a modification of the present invention using optical scanning with a mechanically vibrating rotating polygon mirror; FIG. 4 is a diagram showing the optical scanning system of FIG. 3 from two sides. 5 shows an example of a photographic recording element having a spiral trajectory of spots generated and digitally encoded by the apparatus of FIG. 2; FIG. 5A shows a conventional word group in the word synchronization bits; FIG. 6A is a partially enlarged view of a recording element using separation form bits; FIG. The figure is a partially enlarged view of a recording element using conventional word group separation form bits as the word synchronization bits in Figure 6, Figure 7 is a block diagram of a bit clock circuit used in the device of the present invention, and Figure 8 is a diagram of each. FIG. 9 is a plan view showing the main part of the photographic recording of the present invention having recording synchronization spots of a specific shape, and FIG. 9 is a schematic block diagram showing a part of the synchronization device using the method of recognizing the encoded spots shown in FIG. 8. Fig. 10 is an elevational view of the first optical mask used in the 9th illustrative device, Fig. 11 is an elevational view of the second optical mask used in the 9th illustrative device, and Fig. 12 is offset for synchronization. A plan view of another embodiment of the photographic recording of the present invention using spots, FIG. 13 is a schematic diagram of a synchronization circuit that performs synchronization using information recorded by the method shown in FIG. 12, and FIG. Figure 15 is a diagram showing the edge of a photographic record that has a photosensitive layer and has synchronization information recorded at a position different from the recording position of +iJ audio information, etc.; FIG. 2 is a schematic diagram showing the device.

Claims (1)

[Claims] 1. Digital bits of digital data representing information are recorded at high density on tracks of an optical record carrier in units of data words, and this is optically scanned to generate electrical signals corresponding to individual digital bits. In the method of reproducing the information by generating a pulse, an extra word synchronization bit is added to the digital bit, and the word synchronization bit is approximately equal in size to the digital focus, and has a different shape or recording position from the digital bit. For optical recording and reproducing of digital information, the method comprises: detecting the recorded word synchronization bit to generate a word synchronization signal; and using the word synchronization signal to reproduce the recorded information for each data word. Sync method. 2. the digital bit and the word synchronization bit are recorded in a plurality of small spots along the trunk, the word synchronization spot having a predetermined shape different from the shape of the digital spot, and the detection Claim 1, characterized in that an optical mask is used for reading out the spot in order to detect the shaped spot.
The synchronization method for optical recording and reproducing of digital information as described in . 3. The digital bits and the word sync bits are recorded in a plurality of small spots along the trunk, and only the word sync spot is offset from the track for synchronization, and the word sync bit is offset with respect to the track. The synchronization method for optical recording and reproduction of digital information according to claim 1, characterized in that spots are detected differentially. 4. The digital bit and the word synchronization bit are recorded at different depths of the recording medium during recording, and the image information at different image positions corresponding to the respective depths is optically simultaneously and separately recorded. 2. The synchronization method for optical recording and reproduction of digital information according to claim 1, wherein the synchronization method is performed for each data word using the detected word synchronization bit. 5. Recording the digital bit and the word synchronization bit in different colored layers of the recording medium during recording, and detecting the image information separately by optically reading out the image information using a plurality of color selection detection lights; The synchronization method for optical recording and reproduction of digital information according to claim 1, characterized in that synchronization is achieved for each data word using the detected word synchronization bit.