JPH0427623B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a disc recording and reproducing system for so-called video discs, compact discs, and the like.

If there is dirt or scratches on the disc to be played, the playback signal will drop out and be lost. When the reproduced signal is displayed as an image, the omission of the reproduced signal appears as a black portion or black streak.

In the prior art, in order to prevent the image quality from deteriorating when the image signal is dropped, when the level or frequency of the reproduced signal changes due to the dropout,
It is corrected by replacing it with the signal from one line before. In such prior art, when the frequency of reproduction signal dropouts increases or the dropout period extends over a long period of time, the image cannot be sufficiently corrected, resulting in a significant loss of image quality.

Purpose The present invention provides a disc recording/reproducing method that can maintain good image quality even if a reproduction signal is lost.

Structure of the Invention According to the present invention, the same number of chapters for recording are formed in each of a plurality of recording areas A, B, and C at different locations on a track of a rotationally driven disk, and each of the recording areas A, B, and , C, the same information is recorded in the corresponding chapters of each disc. A pickup means 10 reads the chapters of the disk to obtain a reproduction signal, and a tracking servo circuit moves the pickup means 10 in the radial direction of the disk. 11, a circuit 13 for demodulating the reproduced signal from the pickup means 10; and a circuit 13 for demodulating the reproduced signal from the pickup means 10; A dropout detection circuit 20 generates a signal and generates a signal at the other level during a period in which no quality deterioration occurs, and the output of the dropout detection circuit 20 is integrated by a smoothing circuit having a predetermined discharge time constant. , a switching detection circuit 22 that generates a switching signal when the integral value exceeds a predetermined value, and a switching detection circuit 22 that generates a switching signal, and responding to the outputs of the demodulation circuit 13 and derives data representing the chapter being read by the pickup means 10. in response to the data derivation means 14, 24, the switching signal from the switching detection circuit 22, and the data from the data derivation means 14, 24;
The pick-up means 10 sequentially selects other recording areas B closest to the recording area A being read, and picks up the chapter in the other selected recording area B that corresponds to the chapter whose quality has deteriorated. A control circuit 19 for controlling a tracking servo circuit 11 so as to read the information by the following.

Embodiment FIG. 1 shows the recording state of a disc 1, such as a video disc or a compact disc, according to an embodiment of the present invention. On this disk 1, a plurality of recording areas A, B, and C are arranged in this order. Each recording area A, B, C has chapter numbers 1 to 5, 6 to
It has chapters numbered 10, 11 to 15, ....
The number of chapters in each recording area A, B, and C is the same. The same information is recorded in the corresponding chapter numbers 1, 6, and 11 of each recording area A, B, and C. The same information is recorded in chapter numbers 2, 7, and 12. Further, the same information is recorded in chapter numbers 3, 8, and 13. In this way, the same information is recorded in all the corresponding chapters of recording areas A, B, and C. This information is an image signal and an audio signal.

FIG. 2 is a block diagram of a reproducing apparatus for reproducing disc 1. As shown in FIG. Pickup means 10
is sent in the radial direction along the track of the disk 1 by the tracking servo circuit 11. This tracking servo circuit 11 includes a motor and the like. The signal read out and reproduced by the pickup means 10 is amplified by the amplifier circuit 12 and applied to the demodulation circuit 13. Information is frequency-modulated and recorded on the disk 1. The demodulation circuit 13 performs frequency discrimination on the reproduced signal from the amplifier circuit 12 and supplies it to the processing circuit 14 . The pickup means 10 includes a needle that contacts the video disc 1 or an optical element that scans the video disc 1 with a beam of light and receives the light. The processing circuit 14 is
The video signal from the demodulation circuit 13 is subjected to de-emphasis correction, and when missing, it is replaced with a signal from one line before, and color carrier frequency conversion is performed.
Furthermore, time base correction etc. are performed. The video signal from the processing circuit 14 is displayed by the image display means 15. The audio signal from the demodulation circuit 13 is subjected to de-emphasis correction, noise reduction, and switching between stereo reproduction and monaural reproduction by the audio adjustment circuit 16, and then is applied to the speaker 17 and converted into sound. Volume adjustment circuit 1
6 is controlled by a control circuit 19 that responds to the output from the operation key 18.

The signal from the demodulation circuit 13 is also provided to a dropout detection circuit 20. The loss detection circuit 20 detects that the quality of the signal from the demodulation circuit 13 has deteriorated, for example, that the level of the signal has fallen below a predetermined small value, or that the frequency of the signal from the demodulation circuit 13 has fallen below a predetermined frequency. also decreased.
The missing signal is detected and derived on line 21. The processing circuit 14 performs image deletion correction in response to the omission detection signal 21 . That is, as described above, the information of one line before is given to the image display circuit 15, thereby preventing the image quality from deteriorating.

Switching detection circuit 22 receives the dropout detection signal via line 21. Each time a dropout occurs, this dropout detection signal remains at a high level during the period when a dropout occurs, and is at a low level when no dropout occurs. Switching detection circuit 22
integrates the missing detection signal by a smoothing circuit having a discharge time constant, and outputs a recording area switching signal to line 23 when the integrated value exceeds a predetermined value. When there are frequent dropouts in the playback signal,
When the playback signal is missing for a long time,
The integrated output of the smoothing circuit becomes a high level, and exceeds a predetermined discrimination level, and a recording area switching detection signal is derived.

Among the information recorded on the disk 1, the video signal demodulated by the demodulation circuit 13 includes information such as the chapter of the disk 1, the time from the start of playback, and the number of tracks from the playback start track. It contains a data code such as a so-called page that indicates what is being played. The data reading circuit 24 extracts and reads the data code contained in the video signal processed by the processing circuit 14 and provides the data code to the control circuit 19 . The control circuit 19 controls the tracking servo circuit 11 in response to the recording area switching detection signal from the switching detection circuit 22 via the line 23 and the data code from the data reading circuit 24. For example, while reproducing a chapter having chapter number 2 in recording area A, if the reproduction signal is frequently dropped and a recording area switching detection signal is generated from the switching detection circuit 22, the tracking servo circuit 11 picks up the signal. The means 10 is moved so as to reproduce the chapter number 7 corresponding to the chapter number 2 in the recording area B.
While playing back chapter number 6 of recording area B,
When a large dropout of the reproduced signal occurs, the portion of the corresponding chapter number 12 in the recording area C is reproduced. The control circuit 19 also controls the data reading circuit 24
When the same track on disk 1 is repeatedly played back and a so-called locked group is detected, the recording area switching detection signal is generated.
The pickup means 10 is moved by the tracking servo circuit 11 so as to change the portions of B and C corresponding to the corresponding chapter numbers.

The control circuit 19 performs normal playback in the order of chapter numbers on the disk 1, double-speed playback in which every other line is played back, and other special playback control operations by operating the operation keys 18.

In the above-described embodiment, the level or frequency of the re-signal is level-discriminated to detect omissions in the re-produced signal, but in other embodiments of the present invention, other physical quantities of the re-produced signal can be identified and the reproduced signal can be detected. The quality of the image may be detected.

Effects As described above, according to the present invention, when the same information is recorded in a plurality of recording areas of a disk and the information in a certain recording area is read and reproduced, if the quality of the reproduced signal deteriorates, the remaining Since information is successively read and reproduced from the recording area of the disc, deterioration in image quality is prevented and the life of the disc can be more than doubled.

In particular, according to the present invention, each of a plurality of recording areas A, B, C on a track of a rotationally driven disk
are located at different locations from each other, and each of these recording areas A, B, and C has the same number of chapters for recording, and each corresponding chapter in each recording area A, B, and C has the same number of chapters for recording. When the same information is recorded and the omission detection circuit 20 determines that the quality of the demodulated signal has deteriorated and the reproduced signal obtained by the pickup means 10 is missing. , the control circuit 19 selects another recording area B closest to the recording area A that includes the chapter whose quality has deteriorated, and when the chapter whose quality has deteriorated is included in the recording area B. , sequentially select other recording areas C closest to the recording area B in this way, and select the chapter in the other selected recording area (for example, B or C) corresponding to the chapter whose quality has deteriorated. Since the tracking servo circuit 11 is controlled so that the data is read by the pick-up means 10, frequent movement of the needle or optical element in the pick-up means 10 is prevented, and a stable reading operation can be performed. become able to.

In general, a recording area that includes a chapter with degraded reading quality, for example, A, often includes a plurality of such chapters with degraded quality, and thus includes such a chapter with degraded quality. After the needle and optical element of the pick-up means 10 are moved from the recording area A to read the chapter of another new recording area B,
When the reading quality of a certain chapter deteriorates, the corresponding chapter in another recording area C next to that recording area B is read by the pickup circuit 10. Therefore, after a recording area to be read is selected from recording area A to recording area B, if the quality deteriorates in recording area B, the structure is not configured to return to recording area A again. The recording areas A, B, and C are sequentially selected in this order, and the corresponding chapters are read. Therefore, the needle or optical element in the pick-up circuit 10
For example, the problem of so-called hunting occurring between the recording areas A and B does not occur, and the excellent effect of being able to perform a stable reading operation is achieved.

Furthermore, according to the present invention, the omission detection circuit 20:
During the period when the quality is degraded and the playback signal is missing, a signal of one level (for example, low level) is generated, and during the period when the quality is not degraded, the signal of the other level (for example, high level) is generated. The output of the omission detection circuit 20 is integrated by a smoothing circuit included in the switching detection circuit 22, and this smoothing circuit has a discharge time constant.
Therefore, only when quality deterioration occurs frequently or for a relatively long period of time, the recording area A,
The selection of B and C is sequentially changed, and this also prevents hunting of the needle and optical element in the pickup circuit 10, allowing stable reading operations to continue.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the recording state of a disc 1 according to an embodiment of the present invention, and FIG. 2 is a block diagram of an embodiment of the present invention in which the disc 1 is reproduced. 1...disk, 10...pickup means,
11...Tracking servo circuit, 12...Amplification circuit, 13...Demodulation circuit, 14...Processing circuit, 1
5... Image display circuit, 16... Audio adjustment circuit, 1
7... Speaker, 18... Operation key, 19... Control circuit, 20... Missing detection circuit, 22... Switching detection circuit, 24... Data reading circuit.

Claims (1)

[Claims] 1. A plurality of recording areas A, B, and C located at mutually different locations on the track of a rotationally driven disk.
, the same number of chapters for recording are formed,
The same information is recorded in the corresponding chapters of each recording area A, B, and C. A pickup means 10 reads the chapters on the disk to obtain a reproduction signal, and a pickup means 10 is arranged in the radial direction of the disk. A tracking servo circuit 11 that moves, a circuit 13 that demodulates the reproduction signal from the pickup means 10, and in response to the output of the demodulation circuit 13, the quality of the demodulated signal deteriorates, causing omissions in the reproduction signal. A dropout detection circuit 20 that generates a signal of one level during a period and generates a signal of the other level during a period in which no quality deterioration occurs; and smoothing the output of the dropout detection circuit 20 with a predefined discharge time constant. a switching detection circuit 22 which generates a switching signal when the integrated value exceeds a predetermined value; and a capacitor which responds to the output of the demodulation circuit 13 and is read by the pickup means 10. in response to the switching signal from the switching detection circuit 22 and the data from the data deriving means 14, 24,
The pick-up means 10 sequentially selects other recording areas B closest to the recording area A that is being read, and picks up the chapter in the other selected recording area B that corresponds to the chapter whose quality has deteriorated. 1. A control circuit 19 for controlling a tracking servo circuit 11 so as to read data from a disk.