JP3598838B2 - Data reader - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to data with improved reproduction reliability, which is preferably provided in an information reproducing system for reproducing data from a digital video cassette recorder (hereinafter referred to as a digital VCR) or data supplied from the outside. It relates to a reading device.
[0002]
[Prior art]
In recent years, digital VCRs having a high-speed search function for improving operability have been increasing. However, in general, the data acquisition rate of a digital VCR tends to decrease as the search speed increases. The reason is as follows.
[0003]
First, a digital VCR reads recorded data by tracing a track formed by azimuth recording on a tape. Therefore, at speeds other than 1 × speed, the track direction and the trace direction are different. For this reason, it is theoretically impossible to acquire all data on the track during a high-speed search.
[0004]
Second, since the digital VCR reproduces data by bringing a rotating head into contact with a tape, the acquisition rate of reproduced data depends on the tape running stability. Therefore, in a high-speed search in which the running stability is disadvantageous compared to the normal reproduction, the data acquisition rate decreases.
[0005]
In order to minimize the influence of such a decrease in the data acquisition rate, the digital VCR usually employs a method of multiplexing the same data in different locations depending on the format. However, in actual commercialization, In order to further improve the data acquisition accuracy, a data reading device with improved data reading capability has been devised conventionally.
[0006]
Hereinafter, a conventional data reading device will be described.
2. Description of the Related Art Conventionally, a data reading apparatus described in, for example, JP-A-9-7312 is known. The configuration is shown in FIG. FIG. 5 is a block diagram showing a configuration when a conventional data reading device is applied to a TAG search function of a digital VCR conforming to the DV format.
[0007]
In FIG. 5, 1 is a magnetic tape on which video and audio signals are recorded, 2 is a capstan motor that causes the magnetic tape 1 to run at a predetermined speed by rotating while holding the magnetic tape 1 together with a pinch roller (not shown); Reference numeral 3 denotes a rotary head that converts a magnetic signal recorded on the magnetic tape 1 into an electric signal (hereinafter, referred to as an envelope signal) by a helical scan method. Reference numeral 11 denotes an equalizer circuit for extracting reproduction data from an envelope signal output from the rotary head 3, and reference numeral 12 extracts and outputs system data (hereinafter, referred to as subcode data) storing search information from the reproduction data. Sub-code decoder.
[0008]
Reference numeral 13 denotes a reliability determination circuit that determines the reliability of the subcode data output from the subcode decoder 12 and outputs only highly reliable subcode data, and 14 denotes a reliability determination circuit that outputs the subcode data output by the reliability determination circuit 13. A TAG detection circuit that detects search information (hereinafter, referred to as TAG), 15 is a first counter that counts the number of highly reliable data from the determination result of the reliability determination circuit 13, and 16 is a TAG detection circuit This is a second counter that counts the number of TAG detections from the detection result.
[0009]
Reference numeral 31 denotes a shift register that stores the count values of the first and second counters 15 and 16, and is composed of ten register buffers R0 to R9. Reference numeral 51 denotes a histogram creation circuit that creates a histogram of data from all register values of the shift register 31, and 52 denotes a histogram buffer created by the histogram creation circuit 51 and stored in the most reliable register buffer (R0 to R9). A TAG detection determination circuit 61 determines the presence or absence of TAG detection from the number of detected TAGs, and a system control circuit 61 performs an actual TAG search operation according to the determination result of the TAG detection determination circuit 52.
[0010]
The operation of the conventional data reading device configured as described above will be described below.
[0011]
When a TAG detection command is input to the system control circuit 61, the system control circuit 61 controls the capstan motor 2 to cause the magnetic tape 1 to run at high speed, and starts a desired TAG search operation. At this time, the rotary head 3 performs control such that the scanning speed for the track on the magnetic tape becomes constant, that is, relative speed correction control, and outputs an envelope signal having the same frequency as that during normal reproduction.
[0012]
The equalizer circuit 11 extracts the reproduction data and the reproduction clock signal from the reproduction envelope signal and supplies them to the subcode decoder 12. Further, the sub-code decoder 12 generates sub-code data by sampling the supplied data with the supplied reproduction clock.
[0013]
Here, FIG. 2 is a schematic diagram showing a data format of a subcode of a digital VCR conforming to the DV format.
[0014]
In FIG. 2, reference numeral 53 denotes a recording track recorded on a magnetic tape; 52, a subcode block which is one of the recording tracks 53; 50, a sync block which constitutes the subcode block 52; Of sync blocks.
[0015]
As shown in FIG. 2A, the subcode block 52 is composed of 12 sync blocks 50 (hereinafter, referred to as SBs) having exactly the same data structure per track, and parity information 50a is provided for each SB 50. Is given. Each SB is composed of a subcode data area and an ID area, and the TAG data is stored in an ID0 area 50e in the ID area.
[0016]
The TAG data is composed of three pieces of bit information: INDEX data for searching for a scene, PICTURE / PHOTO data for searching for a still image on a tape, and SKIP data for skipping a scene. Active when bit information is L. As shown in FIG. 2B, each TAG data is multiplex-written in a total of nine SB areas per track of SB1 to SB5 and SB6 to SB11. Writing is defined by the format. This is to ensure that data can be correctly detected even if some of the data cannot be obtained for some reason.
[0017]
The reliability determination circuit 13 determines the reliability of the sub-code data (sync block) generated by the sub-code decoder 12 based on the parity information 50a, and determines only the highly reliable sub-code data as acquisition data as a TAG detection circuit 14. And the number of times of data acquisition per head trace is stored in the first counter 15. For example, when all the subcode data have been acquired, the counter 15 stores the data “12” which is the maximum acquisition number per track trace. Further, the TAG detection circuit 14 detects TAG information recorded in the ID0 area 50e from the supplied subcode data (sync block 50), and stores the number of detections per head trace in the counter 16. For example, when TAG information is detected from seven subcode data out of twelve acquired data, data “7” is stored. As described above, the data “12” stored in the first counter 15 and the data “7” stored in the second counter 16 are both supplied to the first-stage register buffer R0 of the shift register 31. .
[0018]
The shift register 31 shifts the data in the register buffers R0 to R9 in the head trace cycle, and immediately reads the data in the first and second counters 15 and 16 into the register R0. Therefore, the register buffers R0 to R9 store the number of acquired subcode data and the number of detected TAGs for the past 10 traces.
[0019]
Next, the histogram creation circuit 51 creates a histogram of the number of obtained subcode data for the past 10 traces, and detects the TAG detection number data stored in the register buffer having the largest number of acquired data, that is, the largest number of acquired data. The TAG detection number data at that time is output to the TAG detection determination circuit 52.
[0020]
The TAG detection determination circuit 52 sends a TAG detection signal to the system control circuit 61 when the value of the supplied TAG detection number data is larger than a predetermined threshold value. The TAG search operation starts. Specifically, the high-speed tape running is temporarily stopped, and the head is aligned with the TAG writing portion on the tape.
[0021]
Here, the head alignment operation is an operation for correcting a deviation of the tape position when the tape is stopped by detecting a TAG in a high-speed running state. For example, when a TAG search is performed while the tape is running at a high speed, even if the tape is stopped after detecting the TAG data, the actual stop position is a position excessively past the position where the TAG data is recorded due to inertia or the like. Therefore, in order to correctly reproduce from a desired scene, it is necessary to correct this shift amount.
[0022]
FIG. 4 is a schematic diagram illustrating an operation in the case of an INDEX search as a specific example of the head alignment operation.
[0023]
4, first, in the case of an INDEX search in the FF direction, INDEX data is detected at a point A on the tape during the search, and the system control circuit 61 sends a stop command to the capstan motor 2. However, when the search speed is high, the capstan motor 2 cannot be stopped immediately due to inertia or the like, and consequently stops at the point B beyond the INDEX writing period L1. Therefore, after that, the system control circuit 61 runs the tape in the REW direction at a low speed of about 5 to 10 times speed, detects the point C which is the INDEX writing start position, stops the capstan motor 2 again at the same time, and starts reproduction from the point D. Do. Thereby, the recorded video can be reproduced immediately before the desired scene.
[0024]
In the case of the INDEX search in the REW direction, as shown in FIG. 4, INDEX data is detected at the point E on the tape during the search, and the system control circuit 61 sends a stop command to the capstan motor 2. However, when the search speed is high, the capstan motor 2 cannot be stopped immediately due to inertia or the like, and consequently stops at the point F beyond the INDEX writing period. Therefore, after that, the system control circuit 61 causes the tape to run at a low speed of about 5 to 10 times speed in the FF direction, and when the point G which is the INDEX writing head position is detected, reproduction is performed. Thereby, the recorded video can be reproduced immediately after the desired scene.
[0025]
As described above, in the conventional data reading device, even if the number of obtained subcode data decreases or the number of obtained traces varies when a high-speed search is performed, the number of TAGs detected when the number of obtained subcode data is largest is large. Since the presence or absence of TAG detection is determined from data, a correct TAG detection operation is realized.
[0026]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, when an error occurs during data reading for some reason and sub-code data with low reliability is obtained by the reliability determination circuit 13, it is determined whether the sub-code data is incorrect data. I can't judge. Therefore, if such a phenomenon occurs when the reliability determination circuit 13 has the largest number of data acquisitions (tracks), no problem occurs if the acquired data is correct, but if the acquired data is incorrect, TAG detection is performed. May not be able to search for the desired scene due to a failure, and may go too far, or may be erroneously detected even though there is no TAG data, and playback etc. may start from an unrelated scene .
[0027]
Of course, such a phenomenon is unlikely to occur frequently, but it is considered that the possibility increases when various factors such as the recording state of the tape, the state of the running system, and the temperature overlap.
[0028]
The present invention solves the above-mentioned conventional problems, and focuses on the low possibility that low-reliability data is continuously obtained. An object of the present invention is to provide a data reading device in which the reliability of data is determined from a plurality of obtained data and a correct value is estimated, thereby improving the reliability of data acquisition.
[0029]
[Means for Solving the Problems]
In order to achieve this object, a data reading apparatus according to the present invention is a data reading apparatus capable of reading reproduction data such as a video / audio signal and subcode data recorded on a recording medium, and a subcode data recorded on a recording medium. A sub-code decoder for acquiring code data for each track, reliability determining means for determining data reliability from parity information written in a sync block in the sub-code data acquired by the sub-code decoder, Search information detecting means for detecting a sync block including search information among the sync blocks determined to have high reliability by the determining means, and the number of sync blocks including search information detected by the search information detecting means. A counter that counts for each track, and sequentially stores the count value of the counter, A shift register for shifting sub-code data already stored in synchronization with the storage timing, an adding means for integrating data read from the shift register, and detecting that the data read from the shift register has a predetermined pattern. Pattern detecting means for performing search information detection determining means for performing search information detection determination from the addition result from the adding means and the pattern detection result from the pattern detecting means; and And control means for performing a search control of the recording medium.
[0030]
With this configuration, even if data with low reliability is obtained, the reliability of the data is improved by judging the reliability of the data from multiple data obtained before and after that and estimating the correct value. A data reading device can be provided.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
An invention according to claim 1 of the present invention is a data reading apparatus capable of reading reproduction data such as video / audio signals and subcode data recorded on a recording medium, and reads the subcode data recorded on the recording medium. A sub-code decoder for each track; a reliability determining unit for determining data reliability from parity information written in a sync block in the sub-code data obtained by the sub-code decoder; and a reliability determining unit. Search information detecting means for detecting a sync block including search information among the sync blocks determined to have high reliability, and the number of sync blocks including search information detected by the search information detecting means for each track. A counter for counting, and sequentially storing the count value of the counter and synchronizing with the storage timing. A shift register that shifts the already stored subcode data, an adding unit that integrates data read from the shift register, a pattern detecting unit that detects that the data read from the shift register is a predetermined pattern, Search information detection determining means for detecting and determining search information from an addition result from the adding means and a pattern detection result from the pattern detecting means; and a search control of the recording medium based on the determination result of the search information detection determining means. Control means for performing the correction, and has an effect that the data can be corrected effectively even if the reliability of the acquired data is lowered, and the reliability of the reproduction can be improved.
[0032]
An invention according to claim 2 of the present invention is a data reading device capable of reading reproduction data such as video / audio signals and subcode data recorded on a recording medium, and reads the subcode data recorded on the recording medium. A sub-code decoder for each track; a reliability determining unit for determining data reliability from parity information written in a sync block in the sub-code data obtained by the sub-code decoder; and a reliability determining unit. Search information detecting means for detecting a sync block including search information among the sync blocks determined to have high reliability, and the number of sync blocks including search information detected by the search information detecting means for each track. A counter for counting, and sequentially storing the count value of the counter and synchronizing with the storage timing. A shift register for shifting a count value already stored, an adding means for integrating the count value read from the shift register, and a pattern detecting means for detecting that the count value read from the shift register is a predetermined pattern. Search information detection determining means for detecting and determining search information from the addition result from the adding means and the pattern detection result from the pattern detecting means; and a search control of the recording medium based on the determination result of the search information detection determining means. The search information detection determining means determines that the reproduction data is invalid when at least two consecutive count values read from the shift register for each track have the same value. And that even if the reliability of the acquired data is It corrected, an effect that it is possible to improve the reliability of the reproduction.
[0033]
Hereinafter, an embodiment of a data reading device of the present invention will be described with reference to FIGS.
[0034]
(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a data reading apparatus according to the present embodiment, and shows a configuration in a case where the data reading apparatus is applied to a TAG search function of a digital VCR conforming to the DV format.
[0035]
In FIG. 1, 1 is a magnetic tape as a recording medium, 2 is a capstan motor for running the magnetic tape 1, and 3 is a rotary head that converts a magnetic signal recorded on the magnetic tape 1 into an envelope signal by a helical scan method. . Reference numeral 11 denotes an equalizer circuit for extracting reproduction data from the envelope signal output from the rotary head 3, and reference numeral 12 denotes a subcode decoder for extracting and outputting subcode data in which search information is stored from the reproduction data.
[0036]
Reference numeral 13 denotes a reliability judgment circuit which is a reliability judgment means for judging the reliability of the subcode data output from the subcode decoder 12 and outputting only the subcode data having high reliability. A TAG detection circuit, which is a search information detection means for detecting a TAG (search information) from the obtained subcode data, is a counter for counting the number of TAG detections from the detection result of the TAG detection circuit.
[0037]
Further, reference numeral 21 denotes a shift register for storing the count value of the counter 16, which is composed of ten register buffers R0 to R9. Further, 41 is a pattern detection circuit which is a pattern detection means for detecting a specific pattern from the TAG detection number data stored in the register buffers R0 to R9, and 42 adds all the TAG detection number data stored in the register buffer. An addition circuit 43 is an addition means, a TAG detection judgment circuit 43 is a search information detection judgment means for judging the presence or absence of TAG detection in accordance with a detection result of the pattern detection circuit 41 and an operation result of the addition circuit 42, and 61 is a TAG detection judgment circuit 52 Is a system control circuit which is a control means for performing an actual TAG search operation in accordance with the result of the judgment.
[0038]
The operation of the data reading device of the present embodiment configured as described above will be described below.
[0039]
When a TAG detection command is input to the system control circuit 61, the system control circuit 61 controls the capstan motor 2 to cause the magnetic tape 1 to run at high speed, and starts a desired TAG search operation. At this time, the rotary head 3 performs control such that the scanning speed for the track on the magnetic tape becomes constant, that is, relative speed correction control, and outputs an envelope signal having the same frequency as that during normal reproduction.
[0040]
The equalizer circuit 11 extracts reproduced data and a reproduced clock signal from the envelope signal, and supplies them to the sub-code decoder 12. Further, the sub-code decoder 12 generates sub-code data by sampling the supplied data with the supplied reproduction clock.
[0041]
Here, FIG. 2 is an explanatory diagram showing the data format of the subcode of the digital VCR conforming to the DV format.
[0042]
As shown in FIG. 2A, the subcode data 52 is composed of 12 SBs 50 having exactly the same data structure per track, and each SB 50 is provided with parity information 50a. Each SB is composed of a 5-byte subcode data area and a 3-byte ID area, and the TAG data is stored in the ID0 area 50e in the ID area.
[0043]
The TAG data is composed of three pieces of bit information: INDEX data for searching for a scene, PICTURE / PHOTO data for searching for a still image on a tape, and SKIP data for skipping a scene. Active when bit information is L.
[0044]
As shown in FIG. 2B, each TAG data is multiplex-written in a total of nine SB areas per track of SB1 to SB5 and SB6 to SB11. Writing is defined by the format. This is to allow data to be correctly reproduced even if some of the data cannot be obtained for some reason.
[0045]
The reliability determination circuit 13 determines the reliability of the subcode data 52 generated by the subcode decoder 12 based on the parity information 50a written in each SB 50, and determines only the highly reliable SB50 having no parity error as acquired data. , TAG detection circuit 14. Further, the TAG detection circuit 14 detects TAG information written in the ID0 area 50e from the supplied acquired data, and stores the number of TAG detections per head trace in the counter 16.
[0046]
For example, among the 12 SBs 50 per trace, acquired data having no parity error is extracted by the reliability determination circuit 13, and when 7 TAGs are detected by the TAG detection circuit 14, the data “7” is output. Is stored in the counter 16. As described above, the data (the number of SBs detected by the TAG) stored in the counter 16 in the trace cycle is supplied to the first-stage register buffer R0 of the shift register 21.
[0047]
The shift register 21 shifts the data in the register buffers R0 to R9 in the head trace cycle, and immediately reads the data in the counter 16 into the register R0. Therefore, the register buffers R0 to R9 store the TAG detection number data for the past 10 traces.
[0048]
Next, the pattern detection circuit 41 detects a data pattern, which will be described later, from a total of ten pieces of TAG detection information of the register buffers R0 to R9, and the adder circuit 42 generates TAG detection number data stored in the ten register buffers. Is integrated to calculate the total number of detections. Then, the detection result output from the pattern detection circuit 41 and the integration result of the addition circuit 42 are supplied to the TAG detection determination circuit 43 at the same time.
[0049]
When the specific pattern detection information from the pattern detection circuit 41 cannot be obtained, the TAG detection determination circuit 43 determines that the total number of TAG detections output from the addition circuit 42 exceeds a predetermined threshold, specifically “7”. If it has been detected, it is determined that TAG has been detected. However, when the pattern detection circuit 41 detects a predetermined pattern, the presence or absence of TAG detection is determined according to the detection result.
[0050]
FIG. 3 shows a TAG detection pattern detected by the pattern detection circuit 41. In FIG. 3, the X axis of the graph represents the number of traces, that is, the number of data samplings, the Y axis represents the number of TAG detections, the solid line represents the actual number of TAG detections, and the dashed line represents the number of data acquisitions by the reliability determination circuit 13. .
[0051]
FIG. 3A shows a normal TAG detection situation. In this case, the total number of TAG detections in the adding circuit 42 is “25”, which exceeds the threshold “7”. Does not send the pattern detection information to the TAG detection determination circuit 43, and determines the TAG detection based on the total number of TAG detections of the addition circuit 42. In FIG. 3A, the total number of TAG detections is 25, which exceeds the threshold value “7”, so that it is determined that a TAG has been detected.
[0052]
FIG. 3B shows a case where TAG data is detected at least once or more from five or more TAG detection data buffers in the past ten data. Such a situation is likely to occur when the data acquisition rate is reduced overall due to an increase in the search speed or the like. In this case, the pattern detection circuit 41 sends the pattern detection information to the TAG detection determination circuit 43. Accordingly, the TAG detection determination circuit 43 determines that the TAG has been detected based on the data from the pattern detection circuit 41 although the total number of TAG detections by the addition circuit 42 is “6”, which is lower than the threshold value “7”. I do.
[0053]
Further, FIG. 3C shows a case where TAG data is detected only once in the past ten data. When a data reading error occurs for some reason, such a situation may occur even though there is no TAG originally. Also in this case, the pattern detection circuit 41 sends the pattern detection information to the TAG detection determination circuit 43. As a result, the TAG detection determination circuit 43 determines that the TAG is not detected although the total number of TAG detections by the adder circuit 42 is “8” and exceeds the threshold value.
[0054]
As a definition of the above three patterns, when there are two or more discontinuous points of data read from the buffer, it is determined that the reproduced data is invalid. That is, as shown in FIG. 3A, when the number of detected TAGs differs for each adjacent track, it is determined that the reproduced data is valid. On the other hand, as shown in FIGS. 3B and 3C, when there are two or more adjacent tracks having the same TAG detection number for each track, it is determined that the reproduction data is invalid. I do.
[0055]
When TAG detection is determined by the TAG detection determination circuit 43 according to the above algorithm, the system control circuit 61 sends a stop command to the capstan motor 2 to perform head alignment operation.
[0056]
Here, the head alignment operation is an operation for correcting a deviation of the tape position when the tape is stopped by detecting a TAG in a high-speed running state. For example, when a TAG search is performed while the tape is running at a high speed, even if the tape is stopped after detecting the TAG data, the actual stop position is a position excessively past the position where the TAG data is recorded due to inertia or the like. Therefore, in order to correctly reproduce from a desired scene, it is necessary to correct this shift amount.
[0057]
FIG. 4 is a schematic diagram illustrating an operation in the case of an INDEX search as a specific example of the head alignment operation.
[0058]
4, first, in the case of an INDEX search in the FF direction, INDEX data is detected at a point A on the tape during the search, and the system control circuit 61 sends a stop command to the capstan motor 2. However, when the search speed is high, the capstan motor 2 cannot be stopped immediately due to inertia or the like, and consequently stops at the point B beyond the INDEX writing period. Therefore, after that, the system control circuit 61 runs the tape in the REW direction at a low speed of about 5 to 10 times speed, detects the point C which is the INDEX writing start position, stops the capstan motor 2 again at the same time, and starts reproduction from the point D. Do. Thereby, the recorded video can be reproduced immediately before the desired scene.
[0059]
In the case of the INDEX search in the REW direction, as shown in FIG. 4, INDEX data is detected at the point E on the tape during the search, and the system control circuit 61 sends a stop command to the capstan motor 2. However, when the search speed is high, the capstan motor 2 cannot be stopped immediately due to inertia or the like, and consequently stops at the point F beyond the INDEX writing period. Therefore, after that, the system control circuit 61 causes the tape to run at a low speed of about 5 to 10 times speed in the FF direction, and when the point G which is the INDEX writing head position is detected, reproduction is performed. Thereby, the recorded video can be reproduced immediately after the desired scene.
[0060]
As described above, according to the present embodiment, the shift register 21 that sequentially stores the reproduction data at a constant cycle, the pattern detection circuit 41 that is the determination unit, and the TAG detection determination circuit 43 that is the data correction unit are provided. Accordingly, even when the data acquisition rate is low or the reliability of the obtained data is low, correct data reading can be realized by estimating data from past data acquisition patterns.
[0061]
Although the present embodiment is realized by hardware, similar processing may be realized by software.
[0062]
Further, in the present embodiment, there are three types of detection data patterns of the pattern detection circuit 41. However, in order to further improve the accuracy of data acquisition, more detection patterns may be prepared. For example, different detection patterns may be set according to the state of the system to be applied, such as reproduction or high-speed search, and may be switched and used as needed.
[0063]
Further, although the present embodiment describes a digital VCR conforming to the DV format, it may be used in a device other than the DV format.
[0064]
Further, in the present embodiment, the threshold value of the TAG detection determination circuit 43 is set to “7”. However, the threshold value does not need to be a fixed value. For example, in order to further improve the certainty of detection. , May be varied according to the search speed.
[0065]
【The invention's effect】
As described above, according to the present invention, even if low-reliability data is obtained, the reliability of the data is determined from a plurality of data obtained before and after the data, and the correct value is estimated and corrected, whereby the data is obtained. An excellent effect of being able to supply a data reading device with improved acquisition reliability is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram of a data reading device according to an embodiment of the present invention.
FIG. 2 is a schematic diagram showing a configuration of a subcode block in a DV format.
FIG. 3 is a characteristic diagram of a TAG detection pattern of the data reader according to the embodiment;
FIG. 4 is a schematic diagram for explaining a head alignment operation of the data reading device.
FIG. 5 is a block diagram showing a configuration of a conventional data reading device.
[Explanation of symbols]
1 Magnetic tape
12 Subcode decoder
13 Reliability judgment circuit
14 TAG detection circuit
16 counter
21 shift register
41 pattern detection circuit
42 Addition circuit
43 TAG detection judgment circuit
61 System control circuit

Claims (2)

What is claimed is: 1. A data reading apparatus capable of reading reproduction data such as video / audio signals and subcode data recorded on a recording medium, comprising: a subcode decoder for acquiring subcode data recorded on a recording medium for each track; A reliability determining means for determining data reliability from parity information written in a sync block in the sub-code data obtained by the code decoder; and a search among the sync blocks determined to be highly reliable by the reliability determining means. Search information detecting means for detecting a sync block containing information, a counter for counting the number of sync blocks containing search information detected by the search information detecting means for each track, and sequentially counting the count value of the counter. Subcode data stored and already stored in synchronization with the storage timing A shift register for shifting, adding means for integrating the data read from the shift register, pattern detecting means for detecting that the data read from the shift register is a predetermined pattern, and an addition result from the adding means. A search information detection / judgment unit for judging search information from the pattern detection result from the pattern detection unit; and a control unit for performing a search control of the recording medium based on the judgment result of the search information detection / judgment unit. A data reading device characterized by the above-mentioned. What is claimed is: 1. A data reading apparatus capable of reading reproduction data such as video / audio signals and subcode data recorded on a recording medium, comprising: a subcode decoder for acquiring subcode data recorded on a recording medium for each track; A reliability determining means for determining data reliability from parity information written in a sync block in the sub-code data obtained by the code decoder; and a search among the sync blocks determined to be highly reliable by the reliability determining means. Search information detecting means for detecting a sync block containing information, a counter for counting the number of sync blocks containing search information detected by the search information detecting means for each track, and sequentially counting the count value of the counter. The stored count value is shifted in synchronization with the storage timing. Shift register, adding means for integrating the count value read from the shift register, pattern detecting means for detecting that the count value read from the shift register is a predetermined pattern, and an addition result from the adding means. And a search information detection determination unit that performs detection determination of search information from the pattern detection result from the pattern detection unit, and a control unit that performs search control of the recording medium based on the determination result of the search information detection determination unit, The search information detection determining means determines that the reproduction data is invalid when the count value read from the shift register for each track is at least two in succession with the same value. Data reader.

Images