JP3881711B2 - Disc player - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a disc playback apparatus for playing back a disc in which video data and / or audio data encoded at different compression rates for each period are recorded in a plurality of layers.
[0002]
[Prior art]
Japanese Patent Application No. Hei 6-129216 “Disc Player” and Japanese Patent Application No. Hei 6-129216, which have been previously filed, are used as disk reproducing apparatuses for reproducing digital data such as video data and / or audio data encoded at different compression rates for each period. No. 6-130550 “Disc player” is described in detail.
[0003]
A feature of these disk reproducing devices is that the pickup is moved to the inner circumference side of one track according to the degree of fullness of the buffer memory. Control is performed so that the reproduced digital data is not written in the buffer memory until the pickup is reproduced and returned to the moved position. Hereinafter, this control is referred to as track jump control. By performing such track jump control, it is possible to reproduce digital data encoded at different compression rates for each period.
[0004]
[Problems to be solved by the invention]
However, in the above prior art, when playing back a disc in which digital data such as video data and / or audio data encoded at different compression rates for each period is recorded in a plurality of layers, track jump control is performed. If the data reading layer is moved during this time, the position (address) where the track jump control is started cannot be searched again.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, in the present invention, while the writing to the buffer memory for temporarily storing the digital data read from the disk is interrupted and the track jump control is performed on the disk reproducing apparatus, the digital data Do not switch the reading layer.
[0006]
More specifically, the digital data reproduced from the disk is temporarily stored in the buffer memory, and the digital data is output from the buffer memory in response to a request from the decoding means for expanding the digital data. Considering video data, the display frame rate of the video signal is constant, but the video data reproduced from the disc changes the compression rate for each period, so the amount of information necessary for displaying one frame Changes over time. For this reason, the buffer memory overflows or underflows.
[0007]
In the present invention, the pickup is caused to track jump to the inner circumference side according to the degree of fullness of the buffer memory. Data is not written to the buffer memory until the pickup is played back and returned to the position where it was played before jumping.
[0008]
In this way, when digital data having a different compression rate for each period is being reproduced, the track jump control of the pickup is performed at any time according to the sufficiency of the buffer memory.
[0009]
Therefore, in the present invention, when a focus jump command for switching the layer from which digital data is read out is input, the state of the track jump control is first monitored, and when the track jump control is not performed, the pickup control means is immediately In contrast, when the focus jump control is output and the track jump control is being performed, the focus jump control signal is output to the pickup control means at the time when the track jump control is completed, so that the digital compression rate is temporally different. A disc on which data is recorded in a plurality of layers can be reproduced.
In summary, according to the present invention, the track jump control for moving the pickup to the inner circumference side of the disk moves the pickup to the inner circumference side of one track according to the degree of fullness of the buffer memory, and the pickup is moved to the moved position. Until the data is reproduced and returned, control is performed so that the reproduced digital data is not written in the buffer memory. The pickup control means for performing the track jump control detects the amount of data stored in the buffer memory, and when the amount of storage exceeds a predetermined threshold, interrupts the writing of the digital data to the buffer memory and simultaneously from the disk. Track jump control is performed so that the position of the pickup for reading digital data is moved to the inner circumference side, and the pickup is controlled so that the track jumps back to the position where it was played before the track jump from the position where the track jumped. While the control is being performed, the focus jump control is not performed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0011]
FIG. 1 is a block diagram showing a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a disk, in which video data and / or audio data encoded at different compression rates for each period are recorded in two layers. In the following description, the disk 1 is described by taking a disk in which two layers are recorded on one side as an example, but the present invention is not limited to this.
[0012]
Reference numeral 2 denotes a motor. Reference numeral 3 denotes a pickup that reads digital data recorded on the disk 1. A motor control circuit 4 controls the motor 2 so as to rotate at a constant linear velocity. Reference numeral 5 denotes a pickup control circuit, which performs various controls such as pickup focus, tracking control, and transfer control. A preamplifier 6 amplifies and shapes the signal reproduced by the pickup 3.
[0013]
A digital signal processing circuit 7 performs digital signal processing according to the recording format of the disk 1 such as error correction. Descramble circuit 8 detects a synchronization signal in data and cancels scramble. A buffer memory 9 temporarily stores digital data reproduced from the disk. Reference numeral 10 denotes a decoding circuit that decompresses digital data encoded from a disc 1 and encoded with a temporally changing compression rate.
[0014]
Reference numeral 11 denotes an output terminal which outputs a signal expanded by the decoding circuit 9. Reference numeral 12 denotes a buffer memory control circuit, which outputs a track jump command signal 101 in accordance with the fullness of the buffer memory 9. Reference numeral 13 denotes an input terminal to which a focus jump command signal for switching the layer to be reproduced is input.
[0015]
Reference numeral 14 denotes a system control microcomputer, which is a main part in the first embodiment, and the track jump control signal 103 and the focus jump control signal are input to the pickup control circuit 5 by the input track jump command signal 101 and the focus jump command signal 102. 104 is output to control the pickup control circuit 5, write / read control of the buffer memory control circuit 12, control of the motor control circuit 4, system control of the disk reproducing device, and the like.
[0016]
Next, the operation of the disc reproducing apparatus according to the first embodiment shown in FIG. 1 will be described in detail.
[0017]
FIG. 2 shows a cross-sectional view of a disc 1 to be played back by the disc playback apparatus according to the present invention. As shown in the figure, digital data of video data and / or audio data is recorded in the first layer and the second layer, respectively. In FIG. 2, the first layer and the second layer are disposed on one side surface of the disk, but it is natural that the first layer and the second layer may be disposed on both side surfaces of the disk. . The recorded digital data is encoded by changing the compression rate with time.
[0018]
When reproducing digital data recorded on the first layer from the disc 1, the system control microcomputer 14 first outputs a pickup control signal 105 to the pickup control circuit 5. The pickup control circuit 5 controls the focus and tracking of the pickup so as to reproduce the first layer data. At this time, the pickup 3 is focused on the recording surface of the first layer as shown in FIG. 2 (focus 1 in FIG. 2).
[0019]
A signal reproduced from the disk 1 is written into the buffer memory 9 through the preamplifier circuit 6, the digital signal processing circuit 7, and the descramble circuit 8. The buffer memory control circuit 12 outputs a track jump command signal 101 to the system control microcomputer 14 in accordance with the degree of fullness of the buffer memory 9.
[0020]
Next, the operation of the buffer memory control circuit 12 will be briefly described with reference to FIG. Details are described in Japanese Patent Application No. 6-129216 “Disc Playback Device” and Japanese Patent Application No. 6-130550 “Disc Playback Device” filed earlier.
[0021]
Since the digital data recorded on the disc 1 has a temporally different compression rate as described above, there is a difference between the data transfer rate reproduced from the disc 1 and the data transfer rate inputted to the decoding circuit. Arise. Therefore, a buffer memory is provided to absorb the difference.
[0022]
In FIG. 3, when the full state of the buffer memory storage amount is detected at time t1 (see FIG. 3B), the buffer memory control circuit 12 sends the track jump command signal 101 (see FIG. 3C) to the system control microcomputer 14. ) Is output.
[0023]
Receiving this signal, the system control microcomputer 14 outputs a track jump control signal 105 to the pickup control circuit 5, and jumps the pickup 3 to the inside of one track as shown in FIG. At this time, the writing control to the buffer memory is temporarily interrupted, and the writing to the buffer memory is resumed from the time when the signal (m + n) at the time of the track jump is reproduced again (FIGS. 3A and 3D). )reference).
[0024]
By performing such an operation, digital data can be sent to the decoding circuit 10 so that the buffer memory does not overflow.
[0025]
As described above, when reproducing digital data whose compression ratio is changed with time, the disk reproducing apparatus is provided with a buffer memory, and a track jump is performed according to the degree of fullness, and data suitable for the decoding circuit 9 is obtained. It is necessary to match the transfer rate.
[0026]
In the present invention, it is assumed that the digital data is recorded on two layers. Therefore, there is a demand for reproducing digital data of another different layer while reproducing one layer.
[0027]
Meeting such a requirement is a major object of the present invention.
[0028]
Therefore, in the present invention, these pickup control signals are monitored so that track jump control and focus jump control can be performed accurately.
[0029]
Hereinafter, the means will be described with reference to FIGS.
[0030]
FIG. 4 shows an operation flowchart of the system control microcomputer. FIG. 5 shows an example of a command signal and a control signal.
[0031]
When the system control microcomputer 14 detects the focus jump command signal 102, the process proceeds to the focus jump interrupt routine shown in FIG.
[0032]
As shown in FIG. 5A, it is assumed that the focus jump command signal 102 in this embodiment requests reproduction of the first layer when it is at a low level, and reproduction of the second layer when it is at a high level. To do.
[0033]
When the focus jump command signal 102 is detected at the point A in FIG. 5, the system control microcomputer 14 determines whether or not the track jump processing is currently being performed. As shown in FIG. 5B, during the High level, it indicates that the track jump process is being performed, so that the process waits until the process ends. Then, when the track jump process is completed, a focus jump control signal 104 (see FIG. 5C) is output to the pickup control circuit 5 to focus on the second layer in FIG.
[0034]
Similarly, when the focus jump command signal 102 is detected at the point B, it is determined whether or not the track jump processing is being performed. In this case, since it is at the Low level, the focus jump control signal 104 is immediately output to the pickup control circuit 5 to focus on the first layer in FIG. The present invention is not limited to the signal form shown in FIG. 5, and other signal forms may be used.
[0035]
As described above, according to the first embodiment of the present invention, by providing the buffer memory and the buffer memory control circuit, it is possible to reproduce digital data encoded at a compression rate that changes with time. Also, the system control microcomputer detects whether or not the track jump process is in progress. If it is not, the focus jump control signal is output immediately. A jump control signal is output. By performing such an operation, it is possible to selectively switch the layer to be reproduced on the disc in which the digital data is recorded in a plurality of layers.
[0036]
In the above embodiment, the control of the track jump process and the output of the focus jump control signal are all performed by the system control microcomputer 14, but the present invention is not limited thereto, and a dedicated circuit is provided. A similar process may be performed.
[0037]
【The invention's effect】
As described above, according to the present invention, a disk on which a plurality of layers of digital data encoded at a compression rate that changes every period (in time) is recorded continuously without overflowing the buffer memory. It is possible to provide a disc reproducing apparatus which can reproduce and selectively reproduce the layer to be reproduced.
[Brief description of the drawings]
FIG. 1 is a block diagram of a disc playback apparatus according to a first embodiment of the present invention.
FIG. 2 is a disc sectional view showing an example of a disc on which digital data is recorded in a plurality of layers.
FIG. 3 is a diagram for explaining the concept of track jump control.
FIG. 4 is a flowchart showing an operation flow of focus jump control.
FIG. 5 is a diagram illustrating the concept of focus jump control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Disc 2 Motor 3 Pickup 4 Motor control circuit 5 Pickup control circuit 6 Preamplifier circuit 7 Digital signal processing circuit 8 Descramble circuit 9 Buffer memory 10 Decoding circuit 11 Output circuit 12 Buffer memory control circuit 13 Input terminal 14 Microcomputer for system control 101 track jump command signal 102 focus jump command signal 103 track jump control signal 104 focus jump control signal 105 pickup control signal

Claims (5)

A disc playback apparatus capable of playing back a disc having a plurality of recording surfaces in which data encoded at a compression rate that changes every period is recorded on a recording track,
A pickup for reproducing data from the disc;
Storage means for storing data reproduced by the pickup;
Pickup control means for performing track jump control for moving the pickup to the inner circumference side of the disc, or focus jump control for performing focus jump to the recording position of the disc by the pickup to another recording layer. ,
The pickup control means detects the data accumulation amount of the storage means, and when the accumulation amount exceeds a predetermined threshold, interrupts the writing of the digital data to the storage means and simultaneously reads the digital data from the disk Track jump control is performed so that the position of the pickup is moved to the inner circumference side, and the pickup is controlled so that the track jump control returns from the position where the track jump was made to the position where the track was played before the track jump. while being performed, the disk reproducing apparatus, characterized in that does not perform the focus jump control. The disc player according to claim 1, wherein
The disk playback apparatus according to claim 1, wherein the track jump control is performed when an accumulation amount of data stored in the storage unit exceeds a predetermined value. The disc player according to claim 1 or 2,
The disc reproducing apparatus according to claim 1, wherein when the focus jump command signal is received during track jump control, the pickup control means performs focus jump control when the track jump control ends. The disc player according to claim 1, 2 or 3,
A disc reproducing apparatus, wherein the disc has a recording layer only on one side.   4. The disk reproducing apparatus according to claim 1, wherein the disk has recording layers on both side surfaces.

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