JPH0658466U - Signal playback device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a signal reproducing device having excellent earthquake resistance and capable of high-speed continuous data reading (reproduction). A plurality of signal reading means 12a, 12b for reading a digital signal recorded on a recording medium 11, a plurality of signal converting means for converting the read signals detected by the respective reading means, respectively, and a plurality of signal converting means. A plurality of memory means for respectively storing normal read signals, a signal restoration means for restoring the data-converted error-uncorrectable read signals and writing them in the memory means, and a read signal continuous from each memory means And a control means for selectively reproducing sequentially.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a digital signal reproducing apparatus which is used, for example, as a measure for skipping sound in a CD player or as a seismic countermeasure for an optical disk used as an auxiliary storage device from a computer.

[0002]

[Prior art]

 Conventionally, as a measure for skipping sound in a portable CD player, a method has been used in which a reproduction signal from an optical pickup is once stored in a buffer memory to recover the skipping sound and to reproduce the signal while maintaining signal continuity. For example, the block diagram shown in FIG. 2 shows a conventional sound skip prevention circuit, in which a signal recorded on a CD (compact disk) 21 is read by an optical pickup 22 and converted by a signal conversion interface circuit 23. At the same time that the musical tone signal is recorded in the memory 24, a data error uncorrectable signal is added to the musical tone signal and sent to the signal restoration circuit 25. The data transfer rate during this period is double speed (sampling rate is 88.2 KHz).

The signal restoration circuit 25 constantly monitors the data error uncorrectable signal and stores it in the memory 24 as it is in the normal reproduction in which the musical tone data is normally transferred without any skips or scratches on the CD. The musical tone signal thus generated is sent to the DA conversion circuit 26 at a normal speed (sampling speed is 44.1 KHz), and the musical sound data converted into an analog signal is sent to the speaker 28 through the Nyquist filter 27 and reproduced.

During this time, the signal restoration circuit 15 also constantly monitors the state of the memory 14, and if the memory 14 becomes full, it notifies the system control CPU (central processing unit) 29 of the memory overflow. Then, the writing of data from the signal conversion circuit 23 to the memory 24 is stopped. At this time, the CPU 29 causes the pickup 22 to skip back by one track.

The signal to be written in the memory 24 again is adjusted by the signal restoration circuit 25, transferred to the memory 24, and a continuous tone signal is sent to the DA conversion circuit 26. Explaining the signal matching here, for example, in the case of a CD, data in which one frame is 33 bytes is recorded in blocks of 98 frames, and error detection and correction codes are added to each frame. Index information such as the track position called Q code is added to each block of, and when four or more consecutive errors occur, the error uncorrectable signal input to the signal restoration circuit 25 becomes active. . At this time, the signal is repaired by adjusting the data. Specifically, the data is re-input from the optical pickup depending on the position of the Q code immediately before the error occurs, and the immediately preceding 3 including the error occurrence frame. The lower 8 bits of the signal data for 4 samples of the frame are adjusted with the data immediately before the error stored in the memory 24.

Next, there is a case where the signal from the optical pickup 22 input to the signal conversion circuit 23 becomes discontinuous due to sound skipping or damage to the CD. At this time, if error correction is impossible, signal restoration is performed. The error uncorrectable signal input to the circuit 25 becomes active.

When the signal restoration circuit 25 receives a continuous error-uncorrectable active signal that is equal to or greater than a preset value, the signal restoration circuit 25 prohibits data writing to the memory 24, and thereafter the data is stored in the memory 24. Reproduction is continued depending on the tone signal. In this case, the musical tone signal in error must be immediately restored, and the memory 24 must be continuously written and reopened again.

Further, the signal restoration circuit 25 notifies the system control CPU 29 of the occurrence of an error. In response to this, the CPU 29 controls the optical pickup 22 to repeatedly trace several frames before and after the error occurrence frame. Therefore, if the data restoration is successful in the signal restoration circuit 25, a continuous tone signal is sent to the DA conversion circuit 26 via the memory 24 and reproduced.

[0009]

[Problems to be solved by the device]

 By the way, in an environment that vibrates frequently, such as when carrying a portable CD player while jogging and playing music, it is necessary to use the above-mentioned sound skip prevention technology in addition to mechanical vibration suppression technology, but clustering will occur. When data matching is repeated unsuccessfully due to uncorrectable errors, the musical tone signals stored in the memory may be exhausted, resulting in skipping. As a method of improving these, it is possible to increase the signal writing speed from the pickup, or to increase the data transfer speed to the memory by controlling the focus of the pickup or stopping the settling time of the track servo. However, all had limits in terms of machine control. Note that the track servo establishment time here means the time from when the track is reached to when the track is supported by the optical pickup when the track is supported. The optical pick-up is composed of optical equipment, and it means that it takes some time to stabilize the movement of the optical pickup, which is physically heavy.

As a method for solving such a problem, there is a multi-track reading technique in an optical disk data reading device which is an auxiliary storage device such as a computer in the related art. This technique uses a plurality of optical pickups for an actuator that performs track servo. However, there is a problem that the total weight of the data access device to be controlled by the track servo becomes heavy, the track is displaced due to external vibration, and data reading operation is likely to occur.

The present invention has been made in view of the problems of these conventional techniques, and an object of the present invention is to provide a signal reproducing device which is excellent in earthquake resistance and capable of high-speed continuous data reading (reproduction). It is a thing.

[0012]

[Means for Solving the Problems]

 The present invention comprises a plurality of signal reading means for reading digital signals recorded on a recording medium, a plurality of signal converting means for converting the read signals detected by the respective reading means, and a plurality of signal converting means. A plurality of memory means for respectively storing the normal read signals, a signal restoration means for restoring the data-converted read signals which cannot be corrected and writing them to the memory means, and a connection means for each memory means. And a control means for selectively reproducing the read signals sequentially.

[0013]

[Action]

 According to the above configuration, the probability that all the data read from the read means controlled independently of each other at the same time will be erroneous is reduced for a device having a read means that has a mechanically controllable data read speed. The data restoration function of the signal restoration means corresponding to the readout means enables high-speed continuous data reading (reproduction) with excellent earthquake resistance.

[0014]

【Example】

 An embodiment in which the signal reproducing apparatus of the present invention is applied to a sound skip prevention reproducing apparatus for a CD will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of such an apparatus, and the basic components are the same as those of the conventional one. In FIG. 1, 11 is a CD, 12a and 12b are optical pickups as reading means, 13a and 13b are signal conversion interface circuits, 14a and 14b are memories, 15a and 15b are signal restoration circuits, 16 is a DA conversion circuit, Reference numeral 17 is a Nyquist filter, 18 is a speaker, 19 is a CPU, and a changeover switch S1 is interposed between each of the memories 14a and 14b and the DA conversion circuit 16.

Next, the operation of such a configuration will be described. <Operation when the apparatus is stationary> Data of two tracks from the CD 11 are simultaneously read by the two optical pickups 12a and 12b, and respective signals pass through the signal conversion circuits 13a and 13b, and the memory 14a, It is stored in 14b. The sampling frequency at this time is double speed (88.2 KHz), respectively.

On the other hand, the signal restoration circuits 15a and 15b switch the data for each track by controlling the addresses of the signals stored in the memories 14a and 14b, respectively (operation of the switch S1). A signal is transferred to the DA conversion circuit 16 as speed (sampling frequency is 44.1 KHz) continuous data, and the continuous signal thus obtained is reproduced by the speaker 18 through the Nyquist filter 17. At this time, when each memory becomes full, the data reading from each pickup is controlled as in the conventional case. In this case, the optical pickup 12a and the signal conversion circuit 13a are normally skip-traced by two tracks, and when the memory is full, each track is skipped back by two tracks.

<Operation at Occurrence of Reading Malfunction (Sound Drops, etc.)> Next, the signals from the optical pickups 12a, 12b input to the signal conversion circuit 13a or 13b are discontinuous due to skips or scratches on the CD. I will explain the operation when it becomes. The optical pickups 12a and 12b, the signal conversion circuits 13a and 13b, the memories 14a and 14b, and the signal restoration circuits 15a and 15b are paired, and their basic operations are the same as those of the conventional technique.

Consider a case where the data input to the signal conversion circuit 13a has become uncorrectable. At this time, if error correction uncorrectable signals of a set value (4 in this embodiment) or more are continuously input to the signal restoration circuit 15a, the signal restoration circuit 15a prohibits data writing to the memory 14a, and at the same time, The system control CPU 19 causes the optical pickup 12a to skip back one track, and repeatedly traces three frames before and after the error occurrence frame.

At the same time, the system control CPU 29 commands the other optical pickup 12b to trace one track at a time, and either the data restoration by the signal restoration circuit 15a succeeds, or the repetitions occur during 16 times of repeated tracing. Without doing so, continue until you give up adjusting the data, and then skip-trace every two tracks again. Here, 16 of the number of repeated traces is an empirically best value.

All the data stored in the memories 14a and 14b are address-managed by the signal restoration circuits 15a and 15b and transferred to the DA conversion circuit 16 so as to maintain the continuity of signals. In this embodiment, the memories 14a and 14b are shared by one 4 Mbyte RAM, and the data from the respective signal conversion circuits 13a and 13b are distinguished by the address. Note that the pickups 12a and 12b move in a coordinate orthogonal to the rotation surface of the CD 11 in the radial direction, so that the vibration modes of the CD are independent of each other, and a signal from one of the pickups 12a and 12b causes skipping or the like. To prevent the occurrence of

[0022]

[Effect of device]

 According to the present invention, the sound skipping ability of a reproduction signal of a CD player or the like is improved as compared with the conventional one, and when the present invention is used in a static environment, a data reading means such as an optical pickup such as a CDROM, MD, etc. It is expected that the speed of reading data from a device equipped with a device will be improved, and that data reading can be performed at high speed during real-time processing of image information, which was previously difficult.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing the configuration of a signal reproducing device according to the present invention.

FIG. 2 is a block circuit diagram showing a configuration of a conventional signal reproducing device corresponding to FIG.

[Explanation of symbols]

 11, 21 Compact disc 12a, 12b Optical pickup 13a, 13b Signal conversion interface circuit 14a, 14b Memory 15a, 15b Signal restoration circuit 16 DA conversion circuit 17 Filter 18 Speaker 19 System control CPU

Claims (1)

[Scope of utility model registration request] 1. A plurality of signal reading means for reading a digital signal recorded on a recording medium, a plurality of signal converting means for respectively converting the read signals detected by the respective reading means into data, and a data-converted normal signal. A plurality of memory means for respectively storing different read signals, a signal restoration means for restoring the data-converted error-uncorrectable read signals and writing them in the memory means, and a continuous read signal from each of the memory means is selected. Signal reproducing apparatus having a control means for sequentially reproducing sequentially.