JPS5994215A - Data reproducer - Google Patents

Abstract

PURPOSE:To reproduce correctively the prescribed data including an index, etc. by reading two same data which are repetitively recorded and then processing said data with the 1st and 2nd coincidence/dissidence signals and a drop-out detecting signal. CONSTITUTION:The 1st index data signal is supplied to a counter 18; while the 1st signal is stored in a data memory 21. The counter 18 switches a switch 11, and the 2nd signal is supplied to a comparator 22. The comparator 22 delivers ''L'' when the 1st signal is coincident with the 2nd signal. An AND circuit 17 transmits a signal of ''L'' after deciding that the 2nd data is correct, and the 2nd data is delivered via a delay circuit 25. When the comparator 22 decides the dissidence, a drop-out detector 7 is set at ''L'' as long as no 2nd drop-out exists. Then the circuit 17 decides that the 2nd data is correct. In this case, if a drop- out is detected, the output of the detector 7 is set at ''H''. Then the circuit 17 decides the 1st data correct and transmits a signal of ''H'' through a drop-out part. A switch 24 is switched to extract the data supplied to a delay circuit 23 out of the memory 21 as a correct data.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention provides data that enables predetermined data recorded on a recording medium such as an optical recording medium or a magnetic recording medium to be retrieved without error during reproduction. Regarding a playback device.

BACKGROUND ART AND PROBLEMS Conventionally, for example, in a video disc player, predetermined digital data such as index data may be recorded in an audio channel at the beginning of a track. However, no consideration has been given to correction of errors in predetermined digital data such as index data during reproduction. For this reason, if there are scratches or dirt on the surface of the video disc, dropouts may occur and the predetermined digital data may not be reproduced.

OBJECTS OF THE INVENTION An object of the present invention is to provide a data reproducing device that can be used even if there are scratches or dust on a recording medium.

Summary of the Invention The present invention provides a recording medium on which at least two identical data signals are repeatedly recorded, a dropout detector for detecting a dropout of the data signal read from the recording medium, and a dropout detector for detecting a dropout of the data signal read from the recording medium. a data memory that stores the data signal; a comparator that compares the contents of the first data signal and the second data signal stored in the data memory point by point to detect a match or mismatch;
When the output of the comparator is a match or mismatch output with respect to the data signal for the second time, and the detection output of the dropout detector indicates no dropout, the second data signal is extracted as correct data, and the second data signal is extracted as correct data, and When the output of the detector is a mismatch output and the detection output of the dropout detector indicates a dropout, replace the corresponding data content in the first data signal with the dropout part in the second data signal to obtain the correct data. The present invention relates to a data reproducing device characterized in that it is equipped with an error correction circuit for extracting errors.

Example Embodiments of the present invention will be described below with reference to the drawings.

The drawing shows an embodiment of a data reproducing device according to the present invention,
In particular, the case where a video disc is used as the recording medium will be explained. In the figure, a video disc (1) is moved by a drive device (2). The entire predetermined digital data signal, such as an index, is repeatedly recorded at least twice (twice here) in, for example, an audio channel of a video disc (1). During playback, the television signal is picked up from the disc (1) (3)
is read out and fed via a radio frequency amplifier (4) to a first bandpass filter (5), a second bandpass filter (6) and a dropout detector (power).

The audio signal portion is extracted by the first pass filter (5), and the audio signal is extracted from the output terminal (9) via the audio signal demodulator (8). The output of the demodulator (8) is supplied to the movable contact of the switch αυ via the waveform shaping circuit Ql.

Further, the video signal portion taken out from the second bandpass filter (6) is passed through the video signal demodulator (12+) to the 1H delay circuit and the fixed contact L of the switch (14).
o. The output of the 1H delay circuit (l(8)) is supplied to the fixed contact Hi of the switch Q4. switch (1
The output of step 4) is taken out as a video signal from the output terminal αe via the video amplifier α9.

Also, when the dropout detector (7) detects a dropout, the switch a is connected to the fixed contact Hi side,
Dropout detector (when the force does not detect a dropout, the switch α is returned to the fixed contact Lo side.

There is also a dropout detector (the force output is an AND circuit αη
is supplied to one input end of the . Dropout detector (
The output of 7) is at the lHn level when there is a dropout, and at the uL'' level when there is no dropout.

Further, the output of the waveform shaping circuit α0) is supplied to the counter 0 seconds. Then, from the waveform shaping circuit Ql to the counter a8,
When the predetermined first digital data signal mentioned above is supplied, the counter α barrel counts the number of data, and when it reaches a predetermined value, the second digital data signal arrives, so the counter α barrel outputs no output. and switch αυ to the fixed contact Lo side.

Furthermore, the counter α is reset by the reset circuit (I!lI, and when a predetermined number of data of the second digital data signal is counted, the switch 0υ is reset to the fixed contact H.
Return to i side. Then, the first signal is reset by the reset circuit a9. Note that the counter (1 second and reset circuit 0 is the first and second time of the predetermined digital data signal)
A selection circuit for selecting the time is constructed.

The output of the fixed contact Hi side of the switch αυ (first digital data signal) is stored in the data memory QIJ, and the output from the data memory Qυ is supplied to one input terminal of the comparator (2). The output of the fixed contact L0 side of the switch aυ is supplied to the other input terminal of the comparator (221).

The output of data memo v (21) is sent to the 1-bit delay circuit (2
3) to one fixed contact Hi side of the switch Q4). The output (second digital data signal) from the fixed contact Lo side of the switch (1) is supplied to the fixed contact Lo side of the switch (24) via a 1-bit delay circuit (2 groups).

The comparators (two are the outputs of the data memory (21)) and the individual data contents of the first digital data signal and the second digital data signal from the fixed contact Lo side of the switch aυ are detected one by one. When compared, the Ln level (no error) is supplied to the other input terminal of the AND circuit (17), and when there is a mismatch, the uHII level (error detected) is supplied to the other input terminal of the AND circuit (17).

The switch is controlled based on the output of the AND circuit a7). That is, the output of the AND circuit (17) is "H"
'' level, that is, when the first data is correct, the switch (24) is switched to the fixed contact Hi side based on the output of the AND circuit (17).
When the output is at the "L" level, that is, when the second data is correct, the switch Q4) is switched to the fixed contact Lo side based on the output of the AND circuit. Correct digital data is then taken out from the output terminal 00 via the switch (241).

Next, regarding the operation, record the entire digital data signal corresponding to the index, for example, in the audio channel part of the video disc (1) by repeating it over two lines. Even if the digital data corresponding to the index is correct, it is taken out by the pickup (3), and the output of the pickup (3) is sent to the first and second signals via the radio frequency amplifier (4). Bandpass filter (
5) and (6), are fed to the dropout detector (7). The audio signal extracted from the first bandpass filter (5) via the audio signal demodulator (8) is sent out from the output terminal (9) and is sent to the waveform shaping circuit 0 (switch Ql) as a data signal. Memory (21)
My memory is interrupted. When the dropout detector (7) is 'L'' without dropout, the video signal extracted from the second bandpass filter (6) is passed through the video signal demodulator a. Switch Shin, video amplifier (
The dropout detector (7) detects the dropout (“H”) through the output terminal (161).
” level), the switch (14) is switched to the fixed contact Hi side, and the previous signal is sent from the 1H delay circuit α to the output terminal (161) via the switch I and the video amplifier α9.
9 were taken out.

Next, the first pass of the digital data signal corresponding to the index described above is passed through the first band pass filter (5).
, the audio signal demodulator (8), and the waveform shaping circuit a0 to the counter α, the counter QS counts the number of data of the first digital data signal. On the other hand, the first digital data signal is stored in the data memory Qυ via the switch aυ. The counter θ counts all the data of the first digital data signal, and when it reaches a predetermined value, switches the switch aυ to the fixed contact Lo side. Therefore, the second digital data signal is the switch aυ
directly to comparator Q4. Comparator (in the second operation, the individual data contents of the second digital data signal are compared with the individual data contents of the first digital data signal at the corresponding location, and when they match, it becomes 'L'' level (no error υ ) is sent to the AND circuit surface.The AND circuit aη sends out an "L" level signal assuming that the second data is correct, and based on this signal, the movable contact piece of switch C becomes a fixed contact.

Switch to the side. At this time, the corresponding data for the second time is taken out as correct data from the output terminal (A) via the 1-bit delay circuit (C) and the switch (24).

Also, in the comparator t2, the individual data contents of the second digital data signal are compared with the individual data contents of the first digital data signal at the corresponding location,
When they do not match, a signal of (IH'' level (incorrect) is sent to the AND circuit aη.

At this time, even if there is a dropout in the first corresponding data, if there is no dropout in the second corresponding data, the output of the dropout detector (7) will be a 'L' level signal with no dropout. Yes. Therefore,
AND circuit Q7> determines that the second corresponding data is correct and sends out a signal at L' level, and switches the switch to the fixed contact Lo side. This is the 922nd time that the corresponding data is taken out as correct data from the output terminal (2E9) via the 1-bit delay circuit (c) and the switch. 'H
If there is a dropout in the corresponding data for the second time, the dropout detector (force output is tl
This is an Hml level signal (dropout foot).

Therefore, the AND circuit aη assumes that the first corresponding data is correct and sends out a signal of ``tHw level'' at the dropout part, and based on this signal, the switch is switched to the fixed contact Hi side. (
21) is supplied to the 1-bit delay circuit (c), and the corresponding data is taken out as correct data from the output terminal via the switch (2).

As can be seen from the above, when the second digital data signal is compared with the first digital data signal, unless dropouts occur due to scratches, dust, etc. on the video disc (1) or other causes, the , both signals originally match, and perhaps the second data is taken out as correct data. However, when the second digital data signal is compared with the first digital signal, there may be a case where one or both signals do not match at a certain data point due to the aforementioned dropout. At this time, if there is a dropout in the second data that does not match the first data, that data (data in the part where the dropout occurred) is replaced with the first correct data in the second digital data signal. I will have to replace it with the one and take it out. Furthermore, if there is no dropout in the second data that is inconsistent with the first data, it means that there was a dropout in the first data. The second data that does not match the current data is extracted as correct data. Even if a dropout occurs during playback due to scratches or dirt on the video disc (1), the necessary predetermined digital data signals such as the index will be transmitted at least twice (in this embodiment, twice). Since the data is repeatedly recorded on the video disc (1), it is possible to use these two data signals to correctly select necessary predetermined digital data such as an index and reproduce the predetermined data.

In this embodiment, the number of 11th digital data is counted by a counter (l) according to the output of the waveform shaping circuit a, and when it reaches a predetermined value, the switch aυ is switched to the fixed contact LoOIIIK by the output of the counter. However, the present invention is not limited thereto; for example, the first time of predetermined digital data such as an index recorded on the disk (1) without using the selection circuit consisting of the counter 08 and the reset circuit (2) shown in the drawing. The first and second identification signals are inserted at the beginning of the second signal, respectively, and this identification signal is discriminated by a discrimination circuit, and based on this discrimination signal, the switch (11) is set to the first fixed contact Hi side. , the fixed contact may be switched to the LO side for the second time.

In addition, in this embodiment, a video disc is used as a recording medium, and this video disc is an optical disc that is irradiated with a laser beam and observes the diffraction due to the pit row of the disc, and the angle of incidence of the laser beam and its linear deflection. These include optical types such as optical magnetic disks that extract reproduced signals by looking at the angle of the disc, and various other types. The present invention is applicable to various types of recording media such as tapes in addition to the optical recording media and non-optical magnetic disks described above without departing from the gist of the present invention.

Furthermore, in this embodiment, a case has been described in which predetermined digital data (for example, index data) is recorded twice, but the predetermined digital data may be repeatedly recorded multiple times and compared during playback using various methods. It is possible to extract correct data without errors.

Various configurations are possible in this case. For example, with respect to the first and second data, the correct data is extracted with priority to the second data as shown in the embodiment of the drawings, and further this extracted data is stored in a data memory,
This data and the sixth data may be compared as in this embodiment to extract correct data, and the same process may be repeated thereafter to extract even more overwhelming data.

Furthermore, the following can be considered as other embodiments of the present invention.

That is, in the embodiment shown in the drawings, the following recording formats 0) and (b) are used together.

(b) The data clock frequency for predetermined data such as an index is shifted from a multiple of 30 Hz in the case of the NT80 system, and from a multiple of 25 Hz in the PAL/8BOAM system.

(b) The length of the predetermined data is not related to a multiple of the disk rotation period.

Therefore, in the case of (a) above, the same data contents in the first and second predetermined data signals are lined up on a straight line from the center of the disk (1) to the circumference, and in the case of (b) above, In this case, the beginnings of the first and second predetermined data signals, that is, the beginnings of recording are deviated from the above-mentioned one straight line. Disc (1
), if the same data is lined up in the radial direction, the same data points in the first and second data signals will drop out due to scratches (often linear) or dirt. Sometimes, even if the dropout part of the second data is replaced with the first data, the correct data cannot be extracted. However, in other embodiments of the present invention, this problem can be solved and a predetermined data signal can be correctly reproduced.

The present invention is not limited to this embodiment, and various applications and modifications are possible.

Effects of the Invention According to the present invention, even if a dropout occurs in predetermined data such as an index recorded on a recording medium due to scratches or dust attached to the recording medium, errors can be prevented. Predetermined data can be correctly reproduced without any errors, and the effect is extremely large.

[Brief explanation of the drawing]

The drawing is a block circuit diagram showing an embodiment of a data reproducing device according to the present invention. In addition, in the symbols used in the drawings, (1)...
......Video disc (3)...
・・・・・・Pickup (7)・・・・・・・・・
・・・Dropout detector aη・・・・・・・・・・・・
・・AND circuit (21)・・・・・・・・・・Data memory (2nd circuit・・・・・・・Comparator (goods)
・・・・・・・・・・・・It is a switch. Agent Masaru Ueya Yoshio Tsuneko Toshiki Sugiura (I?) 91

Claims (1)

[Claims] a recording medium on which at least two identical data signals are repeatedly recorded; a dropout detector for detecting a dropout of the data signal read from the recording medium; and a dropout detector for storing the first data signal. a comparator that compares the contents of the first data signal and the second data signal stored in the data memory point by point to detect a match or mismatch; On the other hand, when the output of the comparator is a match or mismatch output and the detection output of the dropout detector indicates no dropout, the second data signal is taken out as correct data, and the output of the comparator is a mismatch output. When the detection output of the dropout detector indicates a dropout, the dropout portion Vc in the second data signal is replaced with the cough data content in the first data signal to obtain correct data. A data reproducing device characterized by comprising a circuit.