JP2853729B2 - Data playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data reproducing apparatus suitable for reproducing data reproduced from a disk and storing the data in a buffer memory, and for reading stored information from an external device.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 4-186563 discloses a technique in which data reproduced from a disk is once stored in a buffer memory at a first transfer rate and is output from the buffer memory to an external device at a second transfer rate. There is a digital data reproducing device disclosed in the gazette. This is intended to output data at the transfer rate required for audio and video data even if the rotation speed of the disk is set to a speed suitable for the data transfer rate of a computer or the like. Is used.

[0003] Japanese Patent Laid-Open Publication No. 4-181547 discloses a data reproducing method for a disk device provided with a similar memory means. Further, the publication also discloses a data reproducing method in which when a predetermined amount of data is stored in a memory means, a disk reproducing operation is set to an idling state for a predetermined time. By controlling the idling state to be repeated, the recovery time at the time of track deviation is shortened.

FIG. 6 shows an example of a data reproducing apparatus having such a memory means. In the figure,
A disk 10 as a recording medium includes a spindle motor 1
2 is driven to rotate. Data recorded on the disk 10 is converted and output as an analog reproduction signal S10 by an optical pickup (displayed by PU) 14. The analog reproduced signal S10 is supplied to the channel decoder 18 and the PLL circuit 20 as binarized data S12 after the waveform shaping process and the binarization process by the waveform shaper 16.

In the PLL circuit 20, the binary data S12
, A latch pulse S14 for latching this is generated and supplied to the channel decoder 18. The channel decoder 18 fetches the binary data S12 according to the latch pulse S14, and performs synchronization detection, error detection by CIRC, and correction thereof. Then, the decoded data S16 is written to the buffer RAM 22. In the channel decoder 18, subcode data S 18 including a sector address is extracted from the binary data S 12 and sent to the access control device 24.

On the other hand, in the servo circuit 26, the PLL circuit 2
0, the rotation speed of the spindle motor 12 is changed based on the latch pulse S14 given from the channel decoder 18.
The spindle motor 12 is controlled so as to match a reference clock output from a crystal oscillator (not shown) built in the CPU. In the servo circuit 26, the slide motor 28 and a tracking actuator (not shown) built in the pickup 14 are operated based on the access control signal S20 given from the access control device 24, so that the desired sector of the disk 10 is Access is made.

Next, in the buffer RAM 22, the data S16 supplied from the channel decoder 18 is written according to a reproduction timing signal (not shown) obtained from the channel decoder 18. This data is read out according to a request signal S22 input from the external signal processing device 30, and is supplied to the external signal processing device 30 as read data S24.

Next, control of writing and reading of data to and from the buffer RAM 22 in such a data reproducing apparatus will be described with reference to FIG. FIG. 7 is an operation explanatory diagram showing a data accumulation process in the buffer RAM 22.

The R / W cycle management device 32 monitors the amount of data stored in the buffer RAM 22, and instructs reading and writing of the data. Address comparator 34
Means that the amount of data stored in the buffer RAM 22 is M
This is for determining whether or not the level has exceeded the IN level. The MIN level of the address comparator 34 is a fixed value. When it is determined by the address comparator 34 that the data storage amount has fallen below the MIN level, the read inhibition signal S
26 is output. Then, the external signal processing device 30 stops sending the request signal S22.

[0010] Next, the address comparator 36 has a buffer R
This is for determining whether or not the data storage amount of the AM 22 has exceeded the MAX level shown in FIG. The MAX level of the address comparator 36 is also a fixed value. The amount of data stored is MA by the address comparator 36.
When it is determined that the level has exceeded the X level, a reproduction stop signal S28 is output to the access control device 24.
Then, in the access control device 24, the address of the sector being reproduced on the disk 10 is stored, and the reproduction is stopped from the next sector.

When the stored data in the buffer RAM 22 is read out by the external signal processing device 30 and the amount of stored data falls below the MAX level again, the next sector following the previously stored last reproduced sector is accessed. ,
Data playback is resumed. After that, the data storage amount becomes M
When the data exceeds the AX level, the data reproduction is stopped, and when the data becomes lower than the MAX level, the data reproduction is restarted.
The operation is repeated as shown in FIG.

[0012]

The data storage process in the buffer RAM 22 as described above is further examined.
During a period from the start of data accumulation to the time when the data accumulation amount reaches the MIN level, the data reproducing apparatus is in a reproducing state,
Data is written to the buffer RAM 22. On the other hand, during this period, data reading by the external signal processing device 30 is in a prohibited state, and data reading from the buffer RAM 22 is not performed. Therefore, data is transferred to the buffer RAM at the same speed as the maximum reproduction transfer speed from the disk 10.
22.

Next, the period until the data storage amount exceeds the MIN level and reaches the MAX level is a period during which both writing and reading are permitted, and the buffering speed is obtained by subtracting the reading speed from the data writing speed. RAM 22
The data is stored in

Next, when the data storage amount exceeds the MAX level, the data reproducing apparatus waits for a kickback operation.
Writing of data to the buffer RAM 22 is stopped. When the data storage amount falls below the MAX level again, a search is performed on the data block subsequent to the data block from which data was finally read out of the disk 10 by track jump or head movement. The period indicated by the dotted line in FIG. 7 is the search period. When a predetermined data block is accessed, the data is read and written to the buffer RAM 22.

That is, if the buffer storage amount once exceeds the MAX level after the start of data storage, the data storage device goes up and down the MAX level in the figure unless there is an access operation by an external command or a servo error. Will be. That is, data writing to the buffer RAM 22 is performed intermittently, and three processes of reading one data block, waiting in a kickback operation, and searching by moving the head are repeated in order.
In other words, operations that place a burden on the mechanism, such as search and track jump, are frequently performed,
The deterioration of the mechanism is accelerated.

The present invention focuses on such points, and an object of the present invention is to reduce the frequency of operations, such as search and track jump, which impose a burden on a mechanism, and to improve the life of the mechanism. It is assumed that.

[0017]

SUMMARY OF THE INVENTION The present invention provides a recording medium on which data is recorded in a spiral form; reproducing means for reproducing data from the recording medium; and temporarily storing data reproduced thereby. Memory means for supplying stored data to the outside as required; storage amount comparing means for comparing the data storage amount of the memory means with the lower limit level, the upper limit level, and an intermediate level thereof; Based on the result of comparison by the comparing means, when the data storage amount falls below the lower limit level, data reading from the memory means is prohibited, and when the data storage amount exceeds the upper limit level, data storage in the memory means is stopped. Control means for resuming data storage in the memory means when the amount of accumulated data becomes lower than the intermediate level; The speed is measured, and if the transfer speed is higher than a predetermined value, the intermediate level of the storage amount comparing means is set high. If the transfer speed is lower than the predetermined value, the intermediate level of the storage amount comparing means is set low. Level varying means;

[0018]

[0019]

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Figure 1 are we assume embodiment
Configuration is shown that. The same components as those of the data reproducing apparatus of FIG. 6 described above are described using the same reference numerals.
In FIG. 1, the data storage amount of the buffer RAM 22 is monitored, and an R /
The W cycle management device 50 includes address comparators 34 and 3
6, an address comparator 52 is connected. The output side of the comparison result of the address comparator 52 is connected to the access control device 54. Other parts are the same as those of the background art.

The address comparator 52 is a circuit for determining whether or not the amount of data stored in the buffer RAM 22 is equal to or lower than a preset MID level lower than the MAX level. When the access control device 5
4 is output. Access control device 5
No. 4 stops the reproduction operation of the disk 10 when the reproduction stop signal S28 is input from the address comparator 36, and starts the reproduction operation of the disk 10 when the reproduction start signal S50 is input from the address comparator 52. Has a function.

It should be noted that since the time from the stop to the restart of the data reproduction requires at least one round of the disk, the frequency of kickback cannot be reduced without waiting for a longer time. For this reason, the MID level is set lower than the MAX level by at least the data amount for one rotation of the disk.

As described above, a new MID level is provided at a level lower than the MAX level. The output condition of the reproduction stop signal S28 is when the amount of data stored in the buffer RAM 22 exceeds the MAX level, as in the background art. However, resuming the writing of data to the buffer RAM 22 by starting the reproduction of the disk 10
This is set when the amount of data stored in the buffer RAM 22 falls below the MID level.

Next, the operation will be described with reference to FIG. The basic operation of driving the disk 10 and reproducing data is the same as in the background art, and the reproduction data S16 is written in the buffer RAM 22. This data is
Request signal S input from external signal processing device 30
22 and is supplied to the external signal processing device 30 as read data S24.

In this case, the R / W cycle management device 50 monitors the amount of data stored in the buffer RAM 22, and instructs reading and writing of the data.
The address comparator 34 determines whether or not the amount of data stored in the buffer RAM 22 has exceeded the MIN level shown in FIG. As a result, when it is determined that the data accumulation amount has fallen below the MIN level, the read inhibition signal S26 is output to the external signal processing device 30. Then, the external signal processing device 30 stops sending the request signal S22.

Next, the address comparator 36 determines whether or not the amount of data stored in the buffer RAM 22 has exceeded the MAX level shown in FIG. As a result, when it is determined that the data storage amount has exceeded the MAX level, a reproduction stop signal S28 is output to the access control device 54. Then, in the access control device 54, the disk 10
Is stored, and the reproduction is stopped from the next sector.

The buffer R
When the stored data of the AM 22 is read, the amount of stored data decreases, and eventually falls below the MID level as shown in FIG. Then, the address comparator 52 determines that the data storage amount is equal to or less than the MID level, and the reproduction start signal S5
0 is output to the access control device 54. In the access control device 54, the reproduction operation of the disk 10 is started based on the input of the reproduction start signal S50, the next sector following the last reproduced sector stored earlier is accessed, and the reproduction of data is resumed. Is done.

The reproduced data is stored in the buffer RAM 22
And, if requested, read from the buffer RAM 22 and supplied to the external signal processing device 30. And
When the data accumulation amount exceeds the MAX level, the data reproduction is stopped, and when the data accumulation amount falls below the MID level, the data reproduction is restarted. The above operation is repeated as shown in FIG.

Referring to FIG. 2, the buffer storage amount is MA
It reciprocates between the X level and the MID level, and its cycle is larger than that of the background art in FIG. In other words, the frequency of the track jump and search is lower than the background technology. For this reason, the frequency of operations that impose a burden on the mechanism such as search and track jump is reduced, and the life of the mechanism is improved.

By the way, from the results of FIG. 2 described above, according to increase the difference in MAX level and MID level of the data storage amount, as shown in FIG. 3 (A), the period of the variation of the amount of accumulated data is large Become. The buffer RA
As the data read speed becomes slower than the data write speed to M22, the slope of the curve increases,
As shown in FIG. 3B, the cycle of the fluctuation of the data storage amount becomes smaller.

In view of the above, the greater the difference between the MAX level and the MID level, the less the frequency of track jumps and searches that impose a burden on the mechanism. However, if the MID level is fixedly set lower than the MAX level, the buffer RAM
The data storage amount at 22 decreases, and the margin for retrying a seek operation failure or data reading failure or dealing with an external impact decreases. This level is assumed to be a D level.

As described above, the MID level is low, and
When the frequency of reading data from the buffer RAM 22 is high, that is, when the data accumulation is gradual (the slope of the graph is gradual), as shown in FIG. 4A, it takes time until the data accumulation amount returns to a sufficient level. And the danger period DE1 below the D level in which the data reproducing apparatus cannot sufficiently cope with an operation failure or the like becomes long. When the data reading frequency is low, data accumulation is performed promptly, and the danger period DE3 in which the data level is equal to or lower than the D level is shortened as shown in FIG. 4B. The present embodiment focuses on such a point.

FIG. 5 shows the configuration of the embodiment.
The difference from FIG. 1 is that a transfer rate measuring device 60 is provided. The transfer speed measuring device 60 is for measuring the transfer speed of reading data from the buffer RAM 22 and variably setting the MID level of the address comparator 52 according to the speed value. Specifically, when the data read transfer speed is higher than a predetermined reference speed, the MID
The level is set high, and when the speed is lower than the reference speed, M
The ID level is set low. In both cases,
The MID level is set to a level lower than the D level.

The data read transfer speed of the buffer RAM 22 is measured, for example, by the R / W from the external signal processor 30.
Request signal S22 sent to cycle management device 50
Is counted by the data read clock from the buffer RAM 22 for an arbitrary period.

Next, the operation of the embodiment will be described. The basic operation of the whole, the same as in FIG. That is, in the address comparator 34, the data storage amount of the buffer RAM 22 is M
It is determined whether the IN level has been exceeded. As a result, when it is determined that the data storage amount has fallen below the MIN level, the read inhibit signal S
26 is output. Then, the external signal processing device 30 stops sending the request signal S22.

In the address comparator 36, a buffer RAM
Then, it is determined whether or not the data storage amount of No. 22 has exceeded the MAX level. As a result, when it is determined that the data storage amount has exceeded the MAX level, a reproduction stop signal S28 is output to the access control device 54. Then, the access control device 54 stores the address of the sector being reproduced on the disk 10 and stops reproduction from the next sector.

The buffer R by the external signal processor 30
When the stored data of the AM 22 is read, the amount of stored data decreases and eventually falls below the MID level. Then, the address comparator 52 determines that the data storage amount is equal to or less than the MID level, and outputs a reproduction start signal S50 to the access control device 54. In the access control device 54, based on the input of the reproduction start signal S50, the disc 10
Is started, the next sector following the last-restored sector previously stored is accessed, and data reproduction is resumed. The reproduced data is stored in the buffer RAM
The data is stored in the buffer 22, read out from the buffer RAM 22 when requested, and supplied to the external signal processing device 30.

In the above operation, the transfer rate measuring device 6
At 0, the data read transfer speed in the buffer RAM 22 is measured, and when it is relatively high, the MID level of the address comparator 52 is set high. When the data read transfer rate is relatively high, the buffer R
Data accumulation in the AM 22 is performed slowly. this is,
This corresponds to FIG. 4A described above. In FIG.
The higher the level is set, the faster the search operation becomes, and consequently the shorter the danger period DE. For example, as shown in FIG.
At 2, the danger period DE1 is shortened to DE2.

Conversely, when the data read transfer rate is relatively slow, the MID level of the address comparator 52 is set low. When the data read transfer rate is relatively slow, data accumulation in the buffer RAM 22 is performed quickly. This corresponds to FIG. 4B described above. In the figure, the lower the MID level is set, the slower the search operation becomes, and consequently the longer the danger period DE. For example, as shown in FIG.
From 3 to ML4, the danger period DE3 becomes longer to DE4. However, the difference between the MAX level and the MID level increases, and the frequency of track jumps, searches, and the like that impose a burden on the mechanism unit decreases.

[0040] Thus, according to the embodiment, by controlling the MID level according to the data read transfer rate, while preventing the risk period longer than necessary, the difference between the MAX level and MID level It is possible to reduce the frequency of track jumps, searches and the like by increasing the size.

The present invention can be variously modified based on the above disclosure, and includes, for example, the following. (1) Each block of the device configuration shown in FIGS. 1 and 5 can be variously changed in design so as to exhibit the same operation. (2) The present invention may be applied to any disk medium such as an optical disk and a magneto-optical disk. The data to be handled is also applicable to various data such as audio, video, and computer programs.

[0042]

As described above, according to the present invention, the lower limit level and the upper limit level of the data storage amount of the memory means are provided.
An intermediate level between the data and the
When the data falls below the bell, the data is reproduced and
When restarting writing of data to the
Data according to the data read transfer rate.
To prevent the risk period from becoming unnecessarily long,
Reduces the frequency of rack jumps and searches
To reduce the load on the mechanism and improve its life.
Can be

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration as a premise of the present invention.

FIG. 2 is a graph showing a data accumulation process of a buffer RAM in FIG . 1;

FIG. 3 is a graph showing a relationship between a data transfer rate and a cycle of data accumulation fluctuation.

FIG. 4 is a graph showing a relationship between a data transfer rate and data storage.

FIG. 5 is a block diagram illustrating a configuration of an embodiment.

FIG. 6 is a block diagram showing the configuration of the background art.

FIG. 7 is a graph showing a data accumulation process of a buffer RAM according to the background art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Disc (recording medium) 12 ... Spindle motor (reproducing means) 14 ... Optical pickup (reproducing means) 16 ... Waveform shaper (reproducing means) 18 ... Channel decoder (reproducing means) 20 ... PLL circuit (reproducing means) 22 ... Buffer RAM (memory means) 26 servo circuit (reproduction means) 28 slide motor (reproduction means) 30 external signal processing device 34, 36, 52 address comparator (storage amount comparison means) 50 R / W cycle management Apparatus (control means) 54 ... Access control apparatus (control means) 60 ... Transfer rate measuring apparatus (intermediate level variable means) DE1 to DE4 ... Dangerous period ML1 to ML4 ... MID level S16 ... Reproduction data S22 ... Request signal S24 ... Read data S26: Read stop signal S28: Reproduction stop signal S50: Reproduction start signal

Claims (1)

(57) [Claims] 1. A recording medium on which data is recorded in a spiral form; a reproducing means for reproducing data from the recording medium; temporarily storing the data reproduced by the recording medium; Storage means for comparing the amount of data stored in the memory means with the lower limit level, the upper limit level, and an intermediate level thereof; When the data storage amount is lower than the lower limit level, the data reading from the memory means is prohibited, and when the data storage amount is higher than the upper limit level, the data storage of the memory means is stopped, and the data storage amount becomes the intermediate level. Control means for resuming data storage in the memory means when the following occurs: the data read transfer rate of the memory means is measured, and the transfer rate is measured.
If the degree is faster than the predetermined value, the intermediate level of the accumulation amount comparison means
If the transfer speed is slower than the specified value,
Intermediate level for lowering the intermediate level of the comparison means
A data reproducing device comprising : a variable unit;