JPS63171079A - Information reproducing system - Google Patents

Abstract

PURPOSE:To solve strangeness in a screen by alternately storing information read from a disk every frame in two frame memories and composing the frames of interpolated information consisting of the contents of above-mentioned information and contents of new information and reproduced information. CONSTITUTION:Information obtained by recording alternate frames, which is obtained by thinning the frames of successive program information, in successive tracks is read by a light receiving element 15 twice by twice. The signal is two-divided by a switch 18 through an FM compensator 17 and added 27 through filters 19 and 20 and an FM demodulator 21, 22 to obtain a voice output. Meanwhile, a video signal is two-divided by a switch 37 and stored in a memory 40 through A/D converters 38 and 39. The contents of the frames memories 40 and 41 is incorporated in interpolation circuits 44 and 45 through D/A converters 42 and 43 and an interpolated video signal consisting of the above-mentioned contents and that of new information is transmitted from the switch 37. The signal is set in a proper timing by the switch 46, selected by an analog switch 48 through a correction amplifier, and mixed with a character signal in a mixer 49 so as to output continuous video signals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an information reproducing method for reproducing information recorded on a disc.

(Prior art) In general, conventional techniques include methods that utilize a photographic surface, methods that utilize a surface sensitive to electron beams, magnetic recording methods, and methods that cause irreversible changes in the surface using a beam of radiant energy. It can be divided into methods for writing information. Furthermore, when recording video information on a disk, there are known methods in which high-frequency information is recorded on the disk as continuous spiral tracks or as concentric tracks.

To be viable as a component of a home entertainment device, a video disc must be capable of recording substantial lengths of real-time program information in reproducible form; The total amount of information that can be recorded on a disc is limited by the width of the recording track immediately after the disc, and the linear data density that can be written, recorded, or reproduced. Attempts have been made to increase the recording time by narrowing the pitch, reducing the bit interval and bit size, and increasing the recording density. However, this attempt has certain limitations and has not been put to practical use.

Therefore, a method as shown in Japanese Patent Publication No. 59-35237 shown in FIG. 4 was considered. To briefly explain this method using Fig. 4, (a) only every other frame ((b)) is recorded for the program information ((C)), and when playing back, each recorded frame is Regenerate twice (d))
, a signal that is virtually indistinguishable from the received signal is obtained. However, with this method, there is no problem with slow-moving screens, but with fast-moving screens, an awkwardness appears due to the information in the thinned out frames.

(Problems to be Solved by the Invention) As described above, in the method disclosed in the above publication, only every other frame is reproduced, resulting in awkwardness appearing in one image.

Therefore, the present invention attempts to further extend the program recording time without changing the recording density, and aims to provide an information reproducing apparatus that solves the awkwardness of movement on a television screen during reproduction.

[Structure of the invention]

(Means for Solving the Problems) This invention thins out frames of successive program information and records every other frame on tracks of successive discs,
In this information reproduction method in which the recorded program information is reproduced by reading the same track of the disk twice, the program information for each frame read from the disk is alternately stored in the first and second frame memories. generating interpolation information using the contents of the first or second frame memory and the contents of the frame information of the newly read program information, and composing the frame of the interpolation information with the frame of the reproduced program information. This is an information reproduction method characterized by:

(Operation) Information is recorded in a series of concentric data tracks (C:AV). And instead of recording all the information present during a television transmission, it records every other frame. As a result, data storage requirements are immediately halved and the program content on a given disc is doubled. (
Each frame is preferably recorded during one complete revolution of the disk; upon playback, each recorded frame is played back twice, once written to frame memory; Among them, frame information reproduced from the disk is alternately stored in the first and second frame memories.

Each frame memory sequentially stores frame information that skips one frame, but new information is generated from the information between frame memories, and it is effectively combined with frame information that was not selected at the time of recording. Create indistinguishable program frame information. (By doing this, a reproduced image with supplemented frame information that has been thinned out by one can be obtained.

) (Example) Hereinafter, an example according to the present invention will be described in detail with reference to the drawings.

FIG. 1(a) shows a recording signal system block diagram of an embodiment of the present invention, FIG. 1(b) shows a reproduction signal system block diagram, and FIGS. 2 and 3 show a block diagram of a reproduction signal system. 5 shows a timing chart during playback in the example shown in FIG.

In FIG. 1(a), the NTSC color video signal from the program signal source (FIG. 2(a)) is transmitted to the pre-emphasis circuit 1.
The signal is added to the FM modulator 2 through the delay circuit 3 to achieve time synchronization with the audio signal. The two channel audio signals pass through pre-emphasis circuits 4 and 6, respectively, and are applied to FM modulations s5 and 7, respectively. These two FM waves are simply added by an adder 8.

In order to synthesize the audio signal existing in the unselected frame and the audio signal existing in the selected frame, time synchronization is achieved in the delay circuit 9, and the video FM signal that has passed through the delay circuit 3 is combined with the adder 1o. is synthesized with

The superimposed synchronization signal is used to generate ON/OFF control signals for the analog switch circuit 12 by the frequency dividing circuit 11, and the combined FM signal is guided to the limiter 13 in one frame increments (Fig. 2 (b)) and shaped into a square wave. to control the optical modulator 14. The optical modulator is a type of shutter, and blinks a recording laser beam in response to a square wave to record pits on the photoresist of the master (FIG. 2(c)).

In the reproduction signal system shown in FIG. 1(b), the speed of light diffracted by the bits of the optical disk and reflected back is converted into an electric signal by the light receiving element 15, amplified by the preamplifier 16, and then sent to the FM compensator. Since the same frame information is read twice in the 0 program signal for which changes in frequency characteristics are automatically compensated for in step 17 (Fig. 3(b)), it is divided by analog switch 18 and the audio carrier wave is passed through bandpass filters 19 and 20. Separate each, FMt1tl! I! The first 21 signals are demodulated by the amplifiers 21 and 22, and amplified by the amplifiers 25 and 26 to become the original audio output. Furthermore, by combining them in an adder 27, the audio information of the thinned out frames is also reproduced, and the audio information of the original program signal source can be obtained.

When a dropout (dropout) occurs in the playback signal due to a scratch on the disc, the dropout detection unit 28 detects it, and switches 23 and 2 for both audio channels during the signal dropout period.
4 is opened and the audio level immediately before the switch is opened is maintained to prevent pulse-like dropout noise from occurring during output.

The video FM carrier wave separated by the bandpass filter 29 is directly FM demodulated by the FM demodulator 30, and the FM demodulated wave by the FM demodulator 32 after being delayed by the IH delay line 31 is converted into an analog signal according to the dropout detection signal. Switch 33 is used to obtain the original video signal.

From this demodulated video signal, a code that is pre-entered into a predetermined scanning line during the vertical retrace period is sent to a code separator 34, a burst signal is sent to a burst separator 35, and a synchronization signal is sent to a sync separator 36. Separates specific timing edges and supplies them to the control system and time base servo circuit. These are used to control playback functions, control disk rotation, and remove timebase variations (jitter).

In the video signal as well, since the same frame information is read twice, the analog switch 37 separates the signal into every two frames (every track). This is converted into a digital signal by the A/D converter 38 or 39 and stored in the frame memory (40) or (41) shown in FIGS. 1(c) and (d).

The thinned out frames are generated by using an interpolation circuit 44 or 45 to create the video signal separated by the analog switch 37 and the analog video signal returned to the analog video signal by the D/A conversion 11t42 or 43, and then converting the video signal separated by the analog switch 37 into an appropriate one by using the analog switch 46. At the right timing, this interpolated video signal shown in FIG. 3(e) is sent out. Then, after adjusting the level to an appropriate level with the correction amplifier 47, the analog switch 48 is used to convert the continuous video signal (Fig. 3(f)
) is selected for each frame information.

The reproduced video signal is sent out after being superimposed with a character signal from the control system by a mixer 49 in order to display characters as necessary. Further, the reproduced video signal and the audio signal are transmitted by an RF modulator 51 on a VHF-TV carrier wave of an empty channel. Note that the direct video output is amplified to an appropriate level by an amplifier 50 and then taken out.

As for the timing system, the frequency dividing circuit 52 generates switching pulses for the analog switches 37 and 46 by capturing the timing edge of the tracking servo pulse. Also,
The clear pulse generator 53 initializes the address counter 54, and the crystal oscillation circuit 55 generates a stable address clock to control the addresses of the frame memories 40 and 41.
This is for controlling the analog switch 18 at appropriate timing from the tracking servo pulse and the vertical synchronization signal.

The features of this embodiment can be summarized with reference to FIG. 3: (1) The reproducing head reads the same track on the disk twice, so the tracking servo pulse seeks every two frames. ((b)) ■ By the position of the playback head and the rotation of the disk.

The same video signal is output twice.

■ Frame memory contains, for example, odd-numbered frames,
That is, track information is written one after another, and writing and reading are alternately repeated for each tracking servo pulse. (c) (a) In the frame memory ■, for example, write track information for every even numbered frame, and in addition, similarly to the frame memory ■, writing and reading are repeated alternately for each tracking servo pulse. d) ■ Generate an interpolated video signal from the direct video output from the disk and the video output read from the frame memory ■ or ■. (e) ■ This interpolated video output is mixed with the direct video output from the disk to create continuous frame information and obtain a reproduced video signal that is similar to the original program video signal. (f) becomes.

Moreover, the above interpolation circuit performs interpolation as shown in FIG.
The two signals A and B are synchronously separated and filtered to
Separate the C signal, and separate the Y signal Y of signal A and the Y signal Y of signal B.
Signal YO, C signal C1 of signal A and C signal C2 of signal B
is added, this added signal is halved, and C1+C
, /2. This is to add Y1+Y and /2, respectively. Alternatively, an inverse strix may be placed between the filter and the adder circuit.

The present invention is limited to this embodiment and can be modified in various ways.

〔Effect of the invention〕

According to the present invention described above, compared to conventionally available video disk devices, the program recording time can be doubled without changing the linear data density, and the playback time can also be doubled.
This reduces the cost per disc program time to half, improving economic efficiency.In addition, since frame memory is used during playback, the disc pickup circuit and servo system are used for still playback. This is possible by simply repeating the read address of the frame memory, separate from the operation of .

[Brief explanation of the drawing]

FIG. 1(a) is a block diagram of an embodiment of the recording signal system of the present invention, FIG. 1(b) is a block diagram of an embodiment of the reproduction signal system, and FIG. 2 is a timing chart of the recording signal system. Figure 3 is a timing chart in the reproduction signal system, Figure 4 is the conventional 1.4.6... pre-emphasis circuit 2.5.7... FM modulator 3,9
...Delay circuit 8.10...Adder 1
1... Branch circuit 1z... Analog switch circuit 1
3... Limiter 14... Optical modulator 1
5... Light receiving element 16... Preamplifier 1
7...FM compensator 18...Analog switch circuit
19.20...Band filter 21.22-F Mul
FllMIt 23, 24-Xy Child circuit 25.26...Amplifier 27...Adder 28...Dropout detector 29...Band filter 30.32...FM demodulator 31...
・IH delay line 33...Analog switch circuit 34・
...Code separator 35...Burst separator 3
6... Synchronous separator 37.46.48... Analog switch circuit 38.39... A/D converter 4
0,41...Frame memory 42.43...D/A
Converter 44.45...Interpolation circuit 47...
Correction amplifier 49...Mixer 50...Amplifier 51...RF modulator 52...
Frequency dividing circuit 53...Clear pulse generator 54...Address counter 55...Crystal oscillation circuit 56...Timing generation circuit Fig. 2 Fig. 3 Fig. 4 Fig. 5

Claims (1)

[Claims] In the information reproduction method in which frames of successive program information are thinned out and every other frame is recorded on tracks of successive discs, and the recorded program information is reproduced by reading the same track of the disc twice each time, The program information for each frame read from the disk is stored alternately in first and second frame memories, and the content of the first or second frame memory and the content of the frame information of the newly read program information are stored alternately. generate interpolated information,
An information reproduction method characterized in that a frame of this interpolation information is combined with a frame of the reproduction program information.