JP3173634B2 - Disk recording method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Disk recording method for compressing digital image data obtained by digital conversion and recording on a disk-shaped recording medium
And an apparatus.

[0002]

2. Description of the Related Art As a disk reproducing apparatus for reproducing digital signals from a disk-shaped recording medium, for example, there is a CD player for reproducing digital audio data from a compact disk (CD). In this CD player, a reproduction signal is obtained by reading the difference in the reflectance of pits formed in advance on the disk using an optical head.

[0003] In a disk reproducing apparatus such as a CD player for reproducing a signal from a disk by using optical means, operability such as random access is improved as compared with a tape apparatus or the like. Since the head and the head are not in contact with each other, there is no deterioration of the recording medium and the reliability is very high.

However, in such a disk reproducing apparatus, especially when the apparatus has portability, the focus and tracking of a reproducing optical head for reading a signal from the disk are disturbed and recorded due to disturbance such as vibration and shock. A problem that data cannot be read normally and cannot be reproduced normally (for example, the sound is interrupted in the case of a CD player) is likely to occur.

Such a problem also occurs in a rewritable disk device, that is, a disk recording device. In other words, in a disk recording device, focus or tracking of a recording optical head is caused by disturbance such as vibration or impact. However, there is a problem that normal recording is not performed on the disc.

[0006] In order to solve these problems, conventionally, a method has been adopted in which a mechanical vibration isolating structure is used to suppress disturbance such as vibration or impact to a recording or reproducing optical head. In order to solve this problem using an electric circuit, for example, when a recording or reproduction signal is digital data, there is a method described in Japanese Patent Application No. 4-105270.

[0007]

SUMMARY OF THE INVENTION Among the above prior arts,
In the technology described in Japanese Patent Application No. 4-105270, at the time of recording using a memory, digital data which is a recording signal is once written into the memory, and then read out and recorded on a disk. The transfer speed for reading is higher than the transfer speed for reading, and when data cannot be normally recorded on the disc due to disturbance, the data is accumulated in the memory at any time. Once the digital data, which is a signal, is written to the memory and then read, the transfer speed at the time of writing is made faster than the transfer speed at the time of reading.
By reading the data stored in the memory as needed, the influence of disturbance on the recording signal and the reproduction signal is reduced, and the reliability is improved.

[0008] By the way, a margin for disturbance, that is, an allowable time margin for returning from a tracking error or focus error state (off-track state) to a normal state (on-track state) is not sufficient. And lack of image data is likely to occur,
It is necessary to secure this sufficiently. However, since the margin for this disturbance is determined by the amount of data per unit time input to the memory and the capacity of the memory,
In a disk recording apparatus that converts a signal having a large amount of information, for example, an image signal from analog to digital and records it as digital image data, when the above-described conventional technique is applied, in order to ensure a sufficient margin against disturbance, A capacity of several tens to several hundreds of megabits is required, and the entire apparatus is increased in size, making it difficult to realize a portable disk recording apparatus.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art, to record digital image data with less influence of disturbance, and to secure a sufficient margin against disturbance. In addition, it is an object of the present invention to provide a disk recording method and apparatus which requires a small memory capacity, is small, and is portable.

[0010]

In order to achieve the above object, the present invention provides means for compressing digital image data obtained by analog / digital conversion, and means for controlling a compression ratio in the compression means. A memory unit in which the compressed data is sequentially written, and the written data is read out at a faster transfer speed than at the time of writing; a recording unit that records the read data on a disk-shaped recording medium; Means for detecting and controlling the recording position on the recording medium, and when an abnormality in the recording position is detected by the recording position detection control means, while stopping the read operation of the memory means and the recording operation in the recording means, The compression ratio in the compression unit is changed by the compression ratio control unit.

In the present invention, the change in the compression ratio is controlled based on the relationship between the current position of the recording means and the normal recording position.

Further, according to the present invention, there is provided means for detecting a disturbance such as vibration or impact, and the output of the disturbance detecting means is supplied to the recording position detection control means. Is detected, the recording restart position on the disk-shaped recording medium is controlled by the output of the disturbance detecting means.

[0013]

According to the present invention, when the recording position is abnormal due to disturbance or the like, the compression rate of the compression means is controlled to reduce the amount of data generated per unit time as compared with the memory capacity. Therefore, the time that can be stored in the memory, that is, the time until it returns to the normal recording position can be lengthened, and the lack of image data due to insufficient memory capacity hardly occurs. Further, if the allowance time is the same, the memory capacity can be reduced, and the size of the device can be reduced.

When the change in the compression ratio is controlled based on the relationship between the current position of the recording means and the normal recording position, the recording position is changed from a state in which an abnormality in the recording position is detected due to disturbance or the like to a normal state. Until the recording position is restored, the data compression ratio can be changed in a stepwise manner, so that it is possible to avoid a sudden change in image quality due to a difference in the compression ratio in the recorded image data, and a sense of visual discomfort. Can be prevented from occurring.

Further, when the disturbance detecting means is used, when the recording position abnormality is detected, the disturbance detecting means detects whether the recording position is caused by a disturbance or a disc scratch. Thus, the recording position can be efficiently returned to a normal state.

[0016]

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

FIG. 1 is a block diagram showing a disk recording apparatus as one embodiment of the present invention. In FIG. 1, 1
Is an input terminal of an image signal, 10 is an analog / digital (hereinafter, referred to as A / D) converter, 11 is a compression circuit,
12 is a memory, 13 is a recording circuit, 14 is a recording head, 1
5 is a servo circuit, 17 is a compression ratio control circuit, 18 is a disk recording medium, and 20 is a memory address control circuit.

In FIG. 1, although not shown, an image signal picked up by an image pickup device such as a CCD is input from a terminal 1 and A / D converted by an A / D converter 10 to become digital image data. 11 is input. The compression circuit 11 supplies the image content of the input image data to the compression ratio control circuit 17 and, based on the control signal of the compression ratio from the compression ratio control circuit 17, converts the input image data into a predetermined image. DCT (Discrete Cosine Transcription) is performed for each block (image block refers to each block when an image for one screen is divided into a plurality of blocks).
(sform) The conversion process, the quantization process, the variable-length coding process, and the like are sequentially performed to realize compression of image data.

On the other hand, the compression ratio control circuit 17 controls the compression circuit 1 based on the supplied image contents so that the data amount becomes substantially constant in a predetermined time unit, for example, a frame time unit.
1, a control signal of a compression ratio for each image block, for example, a selection signal of a quantization table used for quantization processing is output.

The compression circuit 11 further includes, for each of the predetermined time units (hereinafter, a unit of data in each of the time units is referred to as a data block), a header including information on a compression ratio for the compressed image data. Information and the like are added and output to the memory 12 as recording data. here,
For example, if the transfer rate of the data input to the compression circuit 11 is 200 Mbps, and this data is compressed by the compression circuit 11 at a compression ratio of 1/20, for example,
The data output to the memory 12 has a transfer rate of 10 Mbps
Becomes continuous data.

In the memory 12, data is sequentially written to the address position specified by the address control circuit 20, and the transfer speed at that time is 10 Mbps.
Next, data is read from the memory 12 after the address control circuit 20 detects that a predetermined amount of data is stored in the memory 12 based on the relationship between the write address and the read address. The transfer is performed intermittently in data block units at a transfer speed higher than the speed, for example, 20 Mbps.

The data output from the memory 12 is subjected to encoding, modulation, amplification and the like in a recording circuit 13, and is recorded on a disk-shaped recording medium 18 by a recording head 14. Here, an index signal indicating a track position is recorded on the disk-shaped recording medium 18 in advance, and the recording head 14 performs a recording operation, detects the index signal, and supplies the index signal to the servo circuit 15. In the servo circuit 15, the data of the data blocks read out intermittently from the memory 12 is recorded on the recording head 14 so as to be continuous on the disk-shaped recording medium 18.
The rotation speed of the disk-shaped recording medium 18, the position of the recording head 14, the recording operation of the recording circuit 13, and the like are controlled based on the supplied index signal.

Next, a description will be given of the operation when the recording position is abnormal due to disturbance such as vibration or impact, that is, when an off-track state is set. The servo circuit 15 is connected to the recording head 14
When the servo circuit 15 detects the off-track state based on the index signal from the
3 and a control signal to the address control circuit 20;
The recording operation is stopped in the recording circuit 13, and the output of the read address is stopped in the address control circuit 20. Further, the servo circuit 15 supplies the compression ratio control circuit 17 with an off-track detection signal and information indicating the track position (normal recording position) of the recording head 14 immediately before the off-track.

When the off-track detection signal is supplied, the compression ratio control circuit 17 increases the compression ratio from a normal state by, for example, forcibly changing the above-mentioned quantization table in the compression circuit 11. , For example, 1/50. Thus, the amount of data input to the memory 12 is
Compared with the normal state, the number is reduced by the amount corresponding to the change in the compression ratio.

Next, the servo circuit 15
, The tracking operation of the recording head 14 is performed, and information indicating the current track position of the recording head 14 (current track position) is supplied to the compression ratio control circuit 17.

The compression ratio control circuit 17 compares the supplied information on the normal recording position with the information on the current track position, and changes the compression ratio in the compression circuit 11. FIG. 2 shows an example of this change. In FIG. 2, the vertical axis represents the compression ratio, and the horizontal axis represents the tracking error amount, that is, the difference between the normal recording position and the current track position. The compression ratio is set smaller as the current track position is closer to the normal recording position.

Next, when the tracking operation by the servo circuit 15 is completed and the recording head 14 enters the on-track state, the servo circuit 15 sends an on-track signal to the compression rate control circuit 17, the address control circuit 20, and the recording circuit 13. Respectively, and among them, the compression ratio control circuit 17
Is, for example, 1/20 of the original compression ratio in the compression circuit 11.
Return to Further, the address control circuit 20 monitors the write address and the read address during the off-track state, and if the write address does not pass the read address during the off-track state, the read address becomes Output is resumed from the address at the time of the stop, and conversely, if the write address exceeds the read address, the output of the read address is output from the address obtained by adding a predetermined amount to the write address when the on-track state is entered. Restart and read data from the memory 12. Further, in the recording circuit 13, the on-track signal from the servo circuit 15
2, the head of the data block of the recording data read out is detected, and the recording operation in data block units is restarted.

Here, an example of the operation of the address control circuit 20 will be described with reference to FIGS. 3, 4, and 5. FIG. 3 and 4
5 is an explanatory diagram showing the temporal change of the write address and the read address. FIG. 3 shows the case where the normal state is established, FIG. 4 shows the case where the off-track state occurs, and FIG.
FIG. 5 shows a case where the write address overtakes the read address in the off-track state. In these figures, the ordinate represents the address and the abscissa represents the time. Therefore, the slope of the solid arrow represents the data transfer speed at the time of writing or reading.

First, in FIG. 3, the write address changes linearly because data is written at a constant transfer rate. On the other hand, since the read address is intermittently read at a transfer speed higher than that at the time of writing, the stop after changing by a certain amount is repeated, for example, for each block.

Next, in FIG. 4, in the off-track state, the compression ratio in the compression circuit 11 increases, and the amount of data written to the memory 12 decreases, so that the write address is the same as that in the normal state. After changing to write valid data at the speed, it stops until the next valid data is transferred. Thereafter, when returning to the on-track state, the compression ratio in the compression circuit 11 returns to the original state, so that the write address changes linearly as in the normal state.
Write data to On the other hand, since the read operation is stopped when the off-track state is set, the read address is stopped, and thereafter, when returning to the on-track state, the read address changes again from the stop address.
Then, since the data is continuously read from the memory 12 until the accumulated data amount reaches the predetermined value, the read address changes continuously, and thereafter, the accumulated data amount becomes the predetermined value. , That is, when the difference between the write address and the read address becomes smaller than a predetermined value, the read address changes intermittently as in the normal state.

FIG. 5 shows a case where the write address overtakes the read address in the off-track state, that is, a case where the amount of data written in the off-track state exceeds the capacity of the memory 12 as described above. However, in FIG. 5, the write address changes in the same manner as in FIG. 4, and even if the address makes one cycle, that is, even if the write data amount in the off-track state exceeds the capacity of the memory 12, the same applies. As a result, the original data after the off-track state is updated to new data one after another. In the off-track state, the read address is stopped as in the case of FIG. However, when returning to the on-track state, the read address starts to change from an address obtained by adding a predetermined amount to the write address at that time. Thereby, data during the off-track state can be recorded as much as possible, and the lack of data can be minimized.

Next, at the time when the above-described series of recording operations is completed, the servo circuit 15 stores the data in the disk management information area provided on the disk-shaped recording medium 18 via the recording circuit 13 and the recording head 14. The position information indicating the area where the data is recorded in the off-track state is written.

As described above, according to this embodiment,
When normal recording is not possible, that is, in the off-track state, the compression rate of the image data is changed to reduce the amount of generated data, so that the capacity of the memory 12 is changed to the on-track state again. , The margin of the time required for the image data can be increased, so that lack of image data hardly occurs, and the reliability can be improved. Also, when in the off-track state, the compression rate of image data is controlled according to the difference between the normal recording position and the current track position. Can be prevented from being changed, and a sense of visual discomfort can be reduced in a change in image quality. Further, even when the off-track state is prolonged and data is written to the memory 12 beyond the capacity of the memory 12, by controlling the address of the memory 12, the lack of image data can be detected immediately after the off-track state. , That is, image data whose image content is disturbed due to vibration, camera shake, or the like. In addition, the position information where the data is recorded when in the off-track state is stored in the disk-shaped recording medium 1.
8, it is possible to quickly search for an image when the compression ratio is changed in the off-track state, and the image at this time is a usable image in work such as editing. It is possible to judge immediately whether or not, it is possible to improve usability.

FIG. 6 is a block diagram showing a disk recording apparatus as another embodiment of the present invention. In FIG. 6, reference numeral 21 denotes an acceleration sensor which detects the acceleration of the movement of the disk recording device or the recording head and estimates the amount of disturbance such as vibration or impact. The same circuit blocks as those in FIG. 1 are denoted by the same reference numerals.

In FIG. 6, since the operation in the normal state is the same as that in FIG. 1, the description is omitted, and only the operation in the off-track state will be described.

In general, the off-track state may be caused by the disturbance such as the above-mentioned vibration or shock, and may also be caused by a defect such as a scratch on the disk-shaped recording medium 18. In the example, the case due to such a defect was not considered.

However, the disk-shaped recording medium 1
8 is turned off-track due to defects such as scratches, the memory 12 cannot be turned on-track.
There is a problem that the amount of data to be written to the memory exceeds the capacity of the memory 12 and the lack of image data occurs when recording is resumed. Also, if there is no disturbance such as vibration or shock, there is no sudden change in the image due to camera shake, etc.
If the compression ratio in the compression circuit 11 changes largely, there is a problem that only the image quality is suddenly deteriorated due to the change in the compression ratio, causing a sense of visual discomfort.

Therefore, in this embodiment, it is determined whether the off-track state is caused by disturbance such as vibration or impact, or by a defect such as a scratch on the disk-shaped recording medium 18, and the determination is made accordingly. The operation is performed.

As described above, since the acceleration sensor 21 can estimate the amount of disturbance, it is easy to determine whether the off-track state is caused by a disturbance or a defect by using the acceleration sensor 21. Can be done. Accordingly, when the servo circuit 15 detects the off-track state, the servo circuit 15
The following processing is performed based on the output from.

That is, when the acceleration from the acceleration sensor 21 is detected by the disk recording device or the recording head 14 as acceleration exceeding a predetermined amount, that is, when a disturbance is detected, the cause of the off-track state is clearly vibration or Since it can be determined that the recording head 14 is caused by a disturbance such as an impact, a tracking operation is performed to return the recording head 14 to the track position (normal recording position) of the recording head 14 immediately before off-track. The operation of other circuit blocks at this time,
The change of the compression ratio in the compression circuit 11 is the same as that in the embodiment of FIG.

Conversely, if the acceleration from the acceleration sensor 21 is equal to or greater than a predetermined amount, that is, if no disturbance is detected, the off-track state is caused by a defect such as a scratch on the disk-shaped recording medium 18. It can be said that the defective portion is an area where recording is not possible, and therefore, a track other than a normal recording position, for example, an adjacent track adjacent to a recording track which is a normal recording position A tracking operation such as returning the recording head 14 to the position is performed. Also at this time, the operation of the other circuit blocks is the same as that of the embodiment of FIG. 1, but the information indicating the normal recording position supplied from the servo circuit 15 to the compression ratio control circuit 17 indicates the original normal recording position. The information is not information indicating the position of the adjacent track adjacent to the original normal recording position as described above, and the change in the compression ratio in the compression circuit 11 set by the compression ratio control circuit 17 is the acceleration sensor 21. Is reduced as compared with the case where a disturbance is detected in. In this case, at the time when a series of recording operations is completed, the servo circuit 15 stores the information in the disc management information area provided on the disc-shaped recording medium 18 via the recording circuit 13 and the recording head 14.
Information indicating the position where the off-track has occurred is written to indicate the unrecordable area.

Therefore, in the present embodiment, when the disk-shaped recording medium 18 goes off-track due to a defect such as a scratch, it is moved to another track position different from the original normal recording position which is a non-recordable area. By performing the tracking operation so as to return the image data to the on-track state immediately, it is possible to solve the problem that the image data is lost when the recording is resumed as described above. In the case where an off-track state occurs due to a defect, the compression circuit 11 operates to reduce the change in the compression ratio, thereby making it difficult for the above-described visual discomfort to occur.

In this embodiment, the acceleration sensor 21 may also be used for correcting camera shake.
This can be realized without increasing the number of parts.

In the above embodiment, the change of the write address to the memory 12 in the normal state is linear as shown in FIGS. 3, 4 and 5, but the present invention is not limited to this. Is not limited to this, and an almost constant data amount generated for each data block is stored in the memory 1.
2 can be written within a unit time, so that, for example, it may be changed stepwise (intermittently), and this does not impair the gist of the present invention and may cause any problem. There is no.

Similarly, the change of the write address in the off-track state is a step-like change (intermittent change) as shown in FIGS. The invention is not limited to this, for example,
The write address may be changed linearly or linearly for each data block, and the write address may be changed so that data generated in the off-track state can be written to the memory 12 within a unit time. This does not impair the gist of the present invention.

In the above embodiment, the compression ratio in the compression circuit 11 in the off-track state is:
Although the quantization table used in the quantization process is changed by forcibly changing the quantization table, the present invention is not limited to this. For example, the data generation amount from the compression circuit 11 may be reduced. The code length may be shortened in the variable length encoding process in the circuit 11. Even in this case, it is apparent that the amount of data generated per unit time is reduced with respect to the capacity of the memory 12, and the same effect can be obtained.

In the above embodiment, when the recording is resumed, the recording circuit 13 detects the head of the data block and resumes the recording. However, the present invention is not limited to this. The data may be recorded for each data block on the recording medium 18.
In the address management of FIG. 5, the write address in the off-track state is managed for each data block.
In such a case as described above, the read address at the time of resuming recording may be set at the beginning of the data block.

In the above embodiment, the case where one memory 12 is used for address management has been described. However, the present invention is not limited to this. For example, a configuration using a plurality of memories may be used. Good. Even in this case, by centrally managing the addresses of the memory,
The same operation can be performed, and the same effect can be obtained.

Further, in the above embodiment, at the time when a series of recording operations is completed, information indicating the position of the data in the off-track state is recorded in a predetermined area of the disk-shaped recording medium 18. However, the present invention is not limited to this. For example, the memory may be recorded in a memory or the like in a disk recording device, or a memory may be attached to the disk-shaped recording medium 18 so that the recording is performed on this. Is also good. Even in this case, the same effect can be obtained.

[0050]

As described above, according to the present invention,
Digital image data can be recorded with less influence of disturbance, and a sufficient margin against disturbance can be secured by controlling the compression ratio of the compression means in the off-track state. Data loss can be reduced,
Since a small memory capacity is required, a compact and portable disk recording device can be realized.

Further, by using the acceleration sensor together, it is possible to accurately perform a tracking operation in the case where an off-track state occurs, and thereby to set an on-track state due to a defect such as a scratch on a disk-shaped recording medium. The problem that image data is lacking due to the above problem can be solved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a disk recording apparatus as one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a change in a compression ratio in a compression circuit 11 of FIG.

FIG. 3 is an explanatory diagram showing an example of a temporal change of a write address and a read address in a normal state.

FIG. 4 is an explanatory diagram showing an example of a temporal change of a write address and a read address when an off-track state occurs.

FIG. 5 is an explanatory diagram showing an example of a temporal change of a write address and a read address when a write address passes a read address in an off-track state.

FIG. 6 is a block diagram showing a disk recording apparatus as another embodiment of the present invention.

[Explanation of symbols]

11 compression circuit, 12 memory, 14 recording head, 1
5 servo circuit, 17 compression ratio control circuit, 18 disk-shaped recording medium, 20 address control circuit, 21 acceleration sensor.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Koji Fujita 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Pref. Hitachi, Ltd. Image Media Research Laboratory (56) References JP-A-63-129560 (JP, A) JP-A-4-61089 (JP, A) JP-A-4-105270 (JP, A) JP-A-5-135501 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 5 / 76-5/956 G11B 20/10-20/12

Claims (11)

(57) [Claims] An input means for inputting an analog signal, and an analog / digital converter for converting the analog signal into a digital signal.
Conversion means for outputting a digital signal, and a compression means for compressing the digital information and outputting compressed information.
Stage, compression ratio control means for controlling a compression ratio in the compression means, and a means for temporarily recording the compressed signal and reading the compressed signal.
A write speed is higher than a write speed, a memory means for recording the compressed information on a disk, and a recording position detection control for detecting and controlling a recording position on the disk.
Control means, said input means, conversion means, compression means, compression ratio control means,
Controls memory means, recording means, recording position detection control means
And control means for recognizing a normal recording position , comprising: a recording position detected by the recording position detection control means;
If the normal recording position is different, stop the recording means
And changing the compression ratio.
Disk recording device. 2. The disk recording apparatus according to claim 1,
There are a detected recording position in said recording position detection control unit,
If the normal recording position is different, the detected recording position
The compression ratio according to the difference between the position and the normal recording position.
A disk recording device characterized by changing 3. The disk recording apparatus according to claim 1,
And a disturbance detecting means for detecting a disturbance, wherein the control means uses a signal from the disturbance detecting means to perform a disturbance detection.
A disk for controlling a compression ratio control means.
Recording device. 4. The disk recording apparatus according to claim 3,
When the disturbance is detected by the disturbance detecting means, the compression ratio is changed according to the magnitude of the disturbance.
Disc recording device. 5. The disk recording apparatus according to claim 1,
There are, further, the recording position information of the compressed information of changing the compression ratio
It is characterized by having position information recording means for recording inside
Disk recording device. 6. The disk recording apparatus according to claim 1,
There are, reading of the memory means when said recording means stops address
If the write address of the memory means overtakes
Even if the recording is continued in the memory means,
Characteristic disk recording device. 7. A digital signal is compressed and compressed information is output.
Compression step, and a compression ratio control step for controlling the compression ratio in the compression step.
And-up, and a recording step of recording the compressed information to the disk, the recording position detection control for detecting controlling the recording position on the disk
And step consists, detected recording position in said recording position detection control step
If the normal recording position is different,
Stopping recording and changing the compression ratio
Disc recording method. 8. The disk recording method according to claim 7, wherein
There, the detected recording position in said recording position detection control step
If the normal recording position is different, the detected
Depending on the magnitude of the difference between the recording position and the normal recording position, the pressure
A disk recording method characterized by changing a reduction ratio. 9. The disk recording method according to claim 7, wherein
There are, disc recording position information of the compressed information of changing the compression ratio
A disk recording method characterized by recording on a disk. 10. The disk recording method according to claim 7, wherein
Oite further has a disturbance detection step of detecting a disturbance, the disturbance is not detected by the disturbance detection step, and before
Recording position detected in recording position detection control step
And when the normal recording position is different, the recording is restarted from a predetermined position.
Recording method. 11. The disk recording method according to claim 10, wherein
In records the positional information of the area is impossible recorded on disk
A disk recording method, characterized in that: