JPS61211843A - Disc device - Google Patents

Abstract

PURPOSE:To correct a focus position always to a proper position and to improve the error rate by changing a focus on a disc by a focus means focused on a disc for light from a light source, using a pre-header recorded on at least one track on the disc to various focus position so as to discriminate the error rate. CONSTITUTION:When a pre-header causes a bias voltage not read by a tracking error or focus error, a control circuit 82 outputs sequentially a signal where a bias voltage generated from a reference signal generating circuit 65 is a voltage subtracting from -IV by IV each to the reference signal generating circuit 65, the error number to each bias voltage (-IV--nV) is obtained and stored in a storage circuit 89. Then the optimum bias is obtained from the error number to each bias voltage stored in the storage circuit 89 and a signal corresponding to the obtained bias is outputted to the circuit 65. Thus, the objective lens 46 is set to the best position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1 of the Invention] The present invention relates to a disk device such as a disc device that records or rewrites information on a disk using, for example, a focusing device 16. Regarding.

[Technical cost of the invention 1 In recent years, image information such as human flesh, which has been generated in large quantities, is photoelectrically converted by two-dimensional optical scanning, and this photoelectrically converted double edge information is recorded on an image recording device, or it is Image information file loading is used which can be searched as needed, reproduced as a hard drive, and outputted as a hard disk.

Conventionally, in this type of pre-disc loading, an optical disc that records information in a spiral is used, and an optical disc that moves in a linear manner in the radial direction of this optical disc is used.
＼ Information is recorded or reproduced from the rad.

[Problems in the Background Art] However, in an optical disk device using a digital disk as described in ``-'', when performing force shifting of an objective lens in an optical IS, there are Therefore, when amplifying the detection signal for force focusing, the focal position is corrected by applying a bias voltage ('71) - 1~voltage). It looks like this.

However, the above-mentioned correction only sets the optimum adjustment position at the time of installation (3 o'clock (at the time of shipment)), that is, the position where the error rate 1 to (error occurrence rate) is the best.

Therefore, deviations due to actual movement (temperature, humidity, vibration,
If a mechanical shift (due to an impact or the like) occurs, the optimum adjustment position will be different and the best error rate will deteriorate. Further, due to the deviation from the adjusted position, the margin for variations in optical disks, deviations in the optical axis due to changes in the external environment, deviations in the position of the photodetector, etc. becomes narrow.

``Object of the Invention This invention was made based on the above circumstances, and its purpose is to be able to always correct the focal position to an appropriate position without adding special data to the disk. (2) It is an object of the present invention to provide a disk g device with improved Raleigh 1- and a wide margin against adjustment position deviation.

[Summary of the Invention] In order to achieve the above object, the present invention records or reproduces information on a disk using focused light, and uses a focusing means to focus light emitted from a light source onto the disk. Change the focusing position on the disk,
Using the pre-header recorded in at least 61 tracks on the disk for the various focused positions that have been changed, determine the error rate to 1, store the various J error rates obtained by this determination, and store the various J error rates obtained by this determination. The optimum focusing position is determined based on the error rule i~, and the focusing means is set at the focusing position corresponding to the result of this determination.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an image information storage and retrieval device according to the present invention. That is, 11 is the main/sub (jO device),
CPU 12 that controls each scale, main memory 13, page buffer 14, compression of image information (reducing redundancy)
and a compression/expansion circuit 15 that performs decompression (returning reduced redundancy), a pattern generator 16 that stores pattern information such as characters or symbols, and a display interface 17. 20
is a reading device, for example, a two-dimensional scanning device, by scanning the original (document) two-dimensionally over 21 with a laser beam light.
An electric signal corresponding to the image information on the original document 21 is obtained. Reference numeral 22 denotes an optical disk device that sequentially stores image information and the like read by the two-dimensional scanning device 20 and supplied via the main controller 11 on the optical disk 19.

As shown in FIG. 2, the optical disc 19 has a donut-shaped metal coating layer such as tellurium or bismuth coated on the surface of a circular substrate made of glass or plastic, for example. There is a notch or reference position mark 191 near the center of the
is provided. Further, on the optical disk 19, the reference position mark 19+ is set to rOJ, and 25 of "O~255" is displayed.
It is divided into 6 sectors.

The optical disc 19 is configured to store variable length information (image information) over a plurality of blocks,
300,000 blocks of information are stored in 36,000 tracks on the optical disk 19. In addition, the number of sectors in one block of the above-mentioned optical disk (d5) is, for example, 40 sectors on the inside and 20 sectors on the outside. Also, if each block does not end at the sector switching position, As shown in the first block and the first block shown in Fig. 2, a block gap is set up so that each block always starts from the sector switching position. A block header (pre-header) A consisting of address data such as , 1 to rack number is recorded, for example, when the optical disc 19 is manufactured.

On the other hand, 23 is a keyboard for inputting a unique search code corresponding to image information and various operation commands. Reference numeral 24 denotes an output device such as a cathode ray tube display device (hereinafter referred to as a CRT display device) which is a display section and is read by a two-dimensional scanning device 20 and sent to the main controller 1.
1 or image information read from the optical disk device 22 and supplied via the main control device 11.
The display interface 17 constitutes a significant image information display device.

25 is a recording device that records image information read by the two-dimensional scanning device 20 and supplied via the main controller 11 or image information read from the optical disk device 22 and supplied via the main controller 11; It is output as a hard copy 26. Reference numeral 27 denotes a magnetic disk device, which performs a search consisting of the size of image information for one item corresponding to the search code entered using the keyboard 23 and the storage address on the optical disk 19 where the image information is stored. Data is stored on the magnetic disk 28 for each piece of image information.

The above search data consists of a search code (image name) consisting of multiple search keys, image information corresponding to this search code (image storage first block number, number of image storage blocks (image length) It consists of

Next, using FIGS. 3 and 4, the optical disk device 22
The configuration of the main parts will be explained. That is, one optical disk is rotated by a motor 30 with respect to an optical head 31 at a constant linear velocity. The above motor 30
A disk 33 on which signal generation marks are provided at regular intervals is fixed to the shaft 32. The marks on the disk 33 are detected optically by a detector 34 consisting of a light emitting diode and a light receiving element. It is designed to detect Furthermore, a detector 35 consisting of a light emitting diode and a light receiving element for optically detecting the reference position mark 191 is provided below the optical disc 19.

The output of the detector 34, that is, the output of the light receiving element is transmitted to the amplifier 3.
G is supplied to the clock pulse input terminal of the sector counter 37, and the output of the detector 35 is supplied to the reset 1 to input terminals of the sector counter 37 via the amplifier section 38.

Further, on the back side of the optical disc 1, an optical head 31 for recording and reproducing information is provided. This optical head 31 is configured as follows. That is, 4
1 is a semiconductor laser (light source), and this semiconductor laser FJ
"4'1 emits divergent laser light. In this case, when writing (recording) information on the recording film 19a of one of the optical discs, a laser whose light intensity is modulated according to the information to be written is used. When light is generated and information is read (reproduced) from the recording film 19a of the optical disk 19, a laser beam having a constant light intensity is generated.The diverging laser beam generated from the semiconductor laser 41 is , is converted into a parallel beam by the collimator lens 43, and guided to the polarizing beam splitter 44. After passing through the polarizing beam splitter 44, the laser light guided to the polarizing beam splitter 44 passes through the quarter-wave plate 4.
5 and enters the objective lens 46, and is focused by the objective lens 46 toward the recording film 19a of one optical disk. Here, the objective lens 46 is supported movably in the front axis direction and in the direction perpendicular to the optical axis, and when the objective lens 46 is positioned at a predetermined position, the focused light emitted from the objective lens 46 is The beam waist of the optical laser beam is projected onto the surface of the recording film 19a of the optical disc 19, and the minimum beam spot is located on the optical disc 1.
9 is formed on the surface of the recording film 19a. In this state, the objective lens 46 is kept in focus and on track, allowing information to be written and read.

In addition, the diverging laser beam reflected from the recording film 19 a of the optical disk 19 is converted into a parallel beam by the objective lens 46 when focused, passes through the quarter-wave plate 45 again, and enters the polarization splitter 44 . be returned. As the laser beam goes back and forth through the 1/4 wavelength plate 45, the pan wavefront of this laser beam is rotated by 90 degrees compared to when it passes through the polarizing beam splitter 44, and the polarization plane is rotated by this 90 degree. Laser light is polarized beam 11 splitter 4
11, but is reflected by this polarizing beam splitter 44. The laser beam 1- reflected by the polarizing beam splitter 44 is divided into two systems by a half mirror 47, and one of the laser beams L (1 Herak deviation detection system) is sent to the first light detection system by the first projection lens 48. The light is irradiated onto the vessel 49. This first photodetector 49
It is composed of photodetection cells 49a and 49b that convert the light imaged by the projection lens 48 into an electrical signal. The signals outputted by these photodetection cells 49a and 49b are a γ signal and a δ signal, respectively.

On the other hand, the other (defocus detection system) laser beam divided by the half mirror 47 is extracted by a knife edge (light extracting member) 50, so that only the component passing through a region separated from the optical axis is extracted. The second photodetector 52 converts the light imaged by the second projection lens 51 into an electrical signal. Photodetection cells 52a, 52b
It is made up of. These photodetection cells 52a,
The signals outputted by 52b are an α signal and a β signal, respectively.

The output of the optical head 30, that is, each photodetection cell 49a,
49b, 52a, 52F) are respectively output to amplifier 6.
Served on 1.62.71.72.

The output of the amplifier 61 is supplied via an amplifier 63 to a non-inverting input terminal of a differential amplifier 68 as a pupil reduction circuit. Further, the output of the amplifier 62 is supplied to a non-inverting input terminal of a differential amplifier 64, and a bias voltage (offset voltage) is supplied from a reference signal generating circuit 65 to the inverting input terminal of the differential amplifier 64. The reference signal generating circuit 65 generates bias voltages (abbreviations) as various reference signals in response to signals (digital signals) supplied from the control circuit 82. This reference signal generation circuit 65
outputs a bias voltage as a reference signal to set the beam spot 1 to the optimum position by the objective lens 16 during recording and reproduction. Further, the reference signal generating circuit 65 outputs a bias voltage for moving the beam spot 1 through the objective lens 16 when detecting the ra rate. for example,
The reference signal generating circuit 65 generates bias voltages of 110 volts, -9 volts, and 110 volts in response to a signal supplied from the control circuit 82.

Further, the output of the differential amplifier 64 is supplied to an inverting input terminal of a differential amplifier 68. As a result, the differential amplifier 68 receives the detection signal from the photodetection cell 52a and the photodetection cell 52b.
By taking the difference between the detection signal from the sensor and the signal obtained by adding an offset voltage to the detection signal, a signal corresponding to the defocus is output. The output of the differential amplifier 68 is the waveform shaping circuit 6
The signal is shaped at 9 and supplied to a drive circuit 70. The drive circuit 70 moves the objective lens 46 onto the recording surface 19 of the optical disc 19 in accordance with a signal supplied from the waveform shaping circuit 69.
The objective lens 46 is driven by supplying a corresponding current to the coil 13 which is driven perpendicularly to the coil 54. □ Also, the output of the amplifier 71 is supplied via an amplifier 73 to a non-inverting input terminal of a differential amplifier 76 as a reduction circuit. Further, the output of the amplifier 72 is supplied to a non-inverting input terminal of a differential amplifier 74, and a bias voltage (offset voltage) is supplied from a reference signal generating circuit 75 to the inverting input terminal of the differential amplifier 74. The reference signal generation circuit 75 outputs a bias voltage as a reference signal so that the beam spot produced by the objective lens 16 is at the optimum position during recording and reproduction, and its value is input to II. It is set during configuration.

Further, the output of the differential amplifier 74 is supplied to an inverting input terminal of a differential amplifier 76. As a result, the differential amplifier 78 receives the detection signal from the photodetection cell 498 and the photodetection cell 49b.
By taking the difference between the detection signal from the rack and the signal obtained by adding an offset voltage to the detection signal, a signal corresponding to the rack shift from 1 for normal to 1 for lagging is outputted as a signal = 14-. The output of the differential amplifier 76 is
The signal is shaped by a waveform shaping circuit 77 and supplied to a drive circuit 78 . The drive circuit 78 moves the objective lens 46 onto the optical disc in accordance with a signal supplied from the waveform shaping circuit 77.
The objective lens 46 is driven by supplying a corresponding current to the lens 53 which is driven in the horizontal direction with respect to the recording surface 19a of the recording surface 19a.

Further, the output of the amplifier 71 and the output of the amplifier 72 are supplied to seven adder circuits. This addition circuit 79 is
The result of tightening these signals is output as a read signal to a binarization circuit 80, which will be described later.

Further, the output of the optical head 30, that is, the output of the adder circuit 79, is supplied to a binarization circuit 80.
The binarized signal is demodulated by the II modulation circuit 81 and supplied to the control circuit 82, and the CRC check circuit 8
7. The demodulation circuit 81 demodulates reproduced data. The control circuit 82 controls the entire device in response to the time signal from an external device, that is, the CPU 12.
It's the same thing. For example, when the control circuit 82 is supplied with a block number for recording or reproducing,
The 1Hz/7 number and start sector number to be accessed are calculated according to a conversion table stored in a conversion table section (not shown). In addition, the control circuit 82 (
Convert the Herak number into a scale value, and convert this scale value to the output of a position detector (not shown) in a linear manner until the detected position matches. The motor driver 83 is driven and controlled. This linear motor driver 83 is configured to move the optical head 31 using a linear motor mechanism 84 under the control of a control circuit 82, so that the beam light from the optical spatula l' 31 irradiates a predetermined track. ”−
The distribution near motor mechanism 84 moves the optical head 31 onto the optical disk 19 in the direction of ¥. When the start sector corresponds to the value of count 1 of the sector counter 37, the recording and reproducing operations of the optical head 31 are started.

Further, the control circuit 82 modulates the recording data from the page buffer j 14 using a modulation circuit 85 and supplies the modulated data to a laser driver 86 . The modulation circuit 85 modulates the recording data supplied from the control circuit 82. The laser driver 86 records data by driving the semiconductor laser 41 within the optical head 31 in accordance with the supplied modulation signal.

The above CRC check (cyclic redundancy)
The check) circuit 87 converts, for example, 16 bytes of data and CR by the demodulation signal supplied from the demodulation circuit 81.
This circuit performs a cyclic redundancy check using C code. The check result by this CRC check circuit 87 is supplied to a counter 88 via a control circuit 82. This counter 88 counts the number of errors supplied. In the error rate check mode, the control circuit 82 stores in the storage circuit f39 the count number (error loop 1~) supplied from the counter 88 for each bias voltage for reproduction of several tracks of blurring.

It is supposed to be done.

Next, the operation in such a configuration will be explained.

For example, now the optical disk drive 22 is set up with the optical interface 19. Accordingly, the CPU 12 determines that it is the -[ra route check mode, and outputs the signal to the control circuit 82.

As a result, the control circuit 82 uses a conversion table section (not shown) to calculate the start 1 to rack number and start sector of the first ivy.

Based on this 1~Herak number, the control circuit 82 converts the 1~Herak number into a scale value, and operates the linear motor driver 83 until this scale value matches the position detected by the output of a position detector (not shown). Drive it. Next, the control circuit 82 brush lid counter 37 runs 1~
When la and the above-mentioned start sector match, the playback of a plurality of i~herakku headers in order from the first block header A is started. The bias voltage outputs a signal from 0 to 1 to the reference signal generation circuit 65.
do.

In such a state, the laser beam flux (reproduction beam light) between divergent weak lights generated from the semiconductor laser 41 is as follows:
The collimator lens 43 converts the light into a parallel light beam, which is guided to a polarizing beam splitter 'I 41c. After passing through the polarization beam splitter 44, the laser beam guided to the polarization beam splitter 44 passes through the quarter wavelength plate 45.
The light passes through and enters the objective lens 46, and is focused by the objective lens 46 toward the recording film 19a of the optical disc 19. In this state, the reflected light from the optical disk 19 for this reproduction beam light is converted into a parallel light beam by the objective lens 7I6, passes through the 1/4 wavelength plate 45 again, and is returned to the polarizing beam splitter 44. As the laser light travels back and forth through the quarter-wave plate 45, the wavefront of the laser light (Iiii) is rotated by 90 degrees compared to when it passes through the polarizing beam splitter 44.
The laser beam whose plane of polarization has been rotated by 1 degree does not pass through the polarizing beam splitter 44.
It is reflected at 4. The radar beam reflected by the polarizing beam splitter 44 is divided into two systems by a half mirror 47, and one of the laser beams (1 to rack deviation detection system) is divided into two systems by a first projection lens 48. The photodetector 49 is irradiated with light.

On the other hand, the laser beam 1- whose ability (defocus detection system) is divided by the half mirror 47 has a large amount of only the component that passes through the area spaced from the optical axis by the narrow edge (optical drawing member) 50. The light passes through the second projection lens 51 and is irradiated onto the photodetector 52 of the rear tube 2. Therefore, signals corresponding to the irradiated light are output from the photodetection cells 52a152b, 49a, and 4.9b, and these are supplied to amplifiers 61, 62, 71, and 72, respectively.

Thereby, the signal from the amplifier 61 is amplified by the amplifier 63 and supplied to the differential amplifier 68.

Further, the output from the amplifier 62 is supplied to a differential amplifier 64. At this time, the reference signal generation circuit 66 supplies a bias voltage of rOJ volts to the differential amplifier 64. As a result, the differential amplifier 64 outputs a signal obtained by adding a bias voltage (OV) to the signal supplied from the amplifier 62 to the differential amplifier 64.
Output to 8. Therefore, the differential amplifier 68 converts the signal obtained by taking the difference between the detection signal from the photodetection cell 52a and the signal obtained by adding the bias voltage (OV) to the detection signal from the photodetection cell 52b to the waveform shaping circuit. The signal is output to the drive circuit 70 via six channels. As a result, the drive circuit 70
supplies a predetermined current to the coil 54 in response to signals from six waveform shaping circuits, drives the objective lens 46 in the vertical direction, and moves the focus position.

In this state, the outputs of the amplifiers 71 and 72 are added together by the adder circuit 79 and supplied to the binarization circuit 80.

Next, the data binarized by the binarization circuit 80 is demodulated by the demodulation circuit 81 and supplied to the control circuit 82 and the CRC check circuit 87. As a result, the control circuit 82
When determining the corresponding 1 to 6 brie header A,
A counter 88 counts the check results of the CRC check circuit 87 for the data successively output as the header. Then, when the preheader A for several tracks is checked, the control circuit 82 sets the contents of the counter 88 as the number of errors for the bias rOVJ in the storage circuit 88.
9 and clear the counter.

Next, the control circuit 82 outputs to the reference signal generation circuit 65 a signal that causes the bias voltage generated by the reference signal generation circuit 65 to be +1 volt. As a result, the amplifier 6
The signal from 1 is amplified by amplifier 63 and supplied to differential amplifier 68 . Further, the output from the amplifier 62 is supplied to a differential amplifier 64. At this time, the reference signal generation circuit 66 supplies a bias voltage of "+1" volt to the differential amplifier 64. As a result, the differential amplifier 64 outputs a signal obtained by adding the bias voltage (+IV) to the signal supplied from the amplifier 62 to the differential amplifier 68. Therefore, the differential amplifier 68 converts the signal obtained by taking the difference between the detection signal from the photodetection cell 52a and the signal obtained by adding the bias voltage (+IV) to the detection signal from the photodetection cell 52b to the waveform shaping circuit. It is output to the drive circuit 70 via 69. Thereby, the drive circuit 70 supplies a predetermined current to the coil 54 according to the signal from the waveform shaping circuit 69, and the objective lens 46
is driven in the vertical direction to move the focus position.

In this state, the outputs of the amplifiers 71 and 72 are added together by the adder circuit 79 and supplied to the binarization circuit 80.

The data binarized by the binarization circuit 80 is then demodulated by the demodulation circuit 81 and supplied to the control circuit 82 and the CRC check circuit 87. As a result, the control circuit 82
determines the preheader A of the rack to the corresponding 1,
A counter 88 divides the check result of the CRC check circuit 87 for the data successively outputted as the header. Then, when the preheader A for several tracks is checked, the control circuit 82 stores the contents of the counter 88 in eight memory circuits as the number of errors for bias r+1VJ, and clears the counter.

Also, when the check for 11 to racks is performed as described above, the number of errors is 50 or more (error rate 1 to 1).
is 10゛4 or more), the control circuit 82
Using the pre-header 8 in the rack, the number of errors is counted and stored in the storage circuit 89 by operating in the same manner as in the above case.

Next, the control circuit 82 sequentially outputs to the reference signal generation circuit 65 a signal that becomes a voltage obtained by adding 1 volt to the bias voltage generated from the reference signal generation circuit 65, and operates in the same manner as described above. Each bias voltage (1V
.about.+nV) is calculated and stored in eight memory circuits.

If the bias voltage of pre-header A becomes unreadable due to tracking error, focus abnormality, etc.,
The control circuit 82 sequentially outputs a signal to the M quasi-signal generation circuit 65 such that the bias voltage generated from the reference signal generation circuit 65 is a voltage obtained by subtracting 1pol 1~ from 1pol 1~ by 1pol 1~.
By operating in the same manner as described above, the number of errors for each bias voltage (-1V to -nV) is determined and stored in the memory circuit 89.

If the bias voltage of the preheader A becomes unreadable due to a racking error, focus abnormality, etc., the control circuit 82 calculates the optimal bias from the number of errors (error rate) for each bias voltage stored in the eight memory circuits. A signal corresponding to the determined bias is output to the reference signal generation circuit 65. For example, as shown in Figure 5, when the bias voltage is 12 volts and +6 volts, the error rate is 10 (50 errors), and when the bias voltage is 11 volts and +5 volts, the error rate is 1~. 10″
5 (error number 5), when the bias voltage is 0 volts +4 volts, the error rate is 104 (error number 0), the optimal bias voltage is determined to be +2 volts, and the reference signal +2 from generation circuit 65
A bias voltage of volts is generated. Thereby, the objective lens 46 can be set at the best position, and the mounting can also have a wide margin against positional deviation. In addition, since the preheader 8, that is, the same data for several tracks is used, and the error rate is determined by reproducing the data by moving the focus position, it is possible to prevent errors in determination from occurring. It is now possible to prevent this error from occurring. Further, it is possible to determine error rule 1 without adding special data to the optical disk 19.

Further, when determining the first number 1 to error rate 1 for the pre-header in the rack as described above, if the number of errors is 50 or more (error rate 10 or more), the control circuit 82 By using the pre-headers of the other several tracks and counting the number of errors in the same manner as in the above case, the error number is stored in the memory circuit 89.
It is designed to determine ~.

In addition, as described above, not only when the optical disc 19 is set, but also when errors such as focus error, misreading (by CRC check), tracking abnormality, and 1~racking jump occur, the objective lens 45
The setting is made to set the optimum force for the 26th position.

Next, the recording of data will be explained in a state where the setting of the optimum focus position and position has been completed as described above. For example, assume that the CPU 12 of the main control device 11 supplies the control circuit 82 with a block number to be recorded (accessed). Then, the control circuit 82 uses a conversion table section (not shown) to calculate the track number and start sector for the target block. Based on this rack number, the control circuit 82 converts the track number into a scale value, and drives the linear motor driver 83 until this scale value matches the position detected by the output of a position detector (not shown). Next, system circuit 82
When the value of the sector counter 37 matches the start sector, recording of data on the optical disc 19 is started. At this point, the recording data from the control circuit 82 is modulated by the modulation circuit 85 and supplied to the laser driver 86. Thereby, the laser driver 86 drives the semiconductor laser 41 in the optical head 31 according to the supplied modulation signal.
Data is recorded by driving the .

I will also explain the playback of the tail. For example, now
Playback is performed from the CPU 12 of the main control device 11 (
It is assumed that the block number (accessed) is supplied to the control circuit 82. Then, the control circuit 82 calculates the rack number from 1 to the rack number and the starting sector for the target block using a conversion table section (not shown). J to this track number
The control circuit 82 converts the track number into a scale value, and drives the linear motor driver 83 until this scale value matches the position detected by the output of a position detector (not shown). Next, the control circuit 82 starts reproducing data for one optical disk when the non-unknown value of the sector counter 37 matches the start sector. At this time, the read signal of the optical head 31 is 2. The signal supplied to the digitization circuit 80 and binarized by the binarization circuit 80 is supplied to the demodulation circuit 81. This demodulation circuit 8-1 demodulates the signal supplied from the binarization circuit 80. The demodulated playback data is then output to the control circuit 82. Then, the control circuit 82 outputs the playback data to the page buffer 14 in the main control device 11.

That is, the polygonal laser beam generated from the semiconductor laser 41 is converted into a parallel beam by the collimator lens 43 and guided to the polarizing beam splitter 44 . The laser beam guided to this polarizing beam splitter 44 passes through this polarizing beam splitter 44 and then passes through a 1/4 wavelength plate 45 and enters an objective lens 46. It is focused towards the membrane 19a. In this state, when recording information, pips 1 to 1 are formed on the tracks on the optical disk 19 by irradiation with a high-intensity laser beam (recording beam light), and when recording information is not being irradiated with the recording beam light, and when reproducing information, use a low-intensity laser beam (reproduction beam light).
is irradiated. Optical disc 1 for this reproduction beam light
The reflected light from the polarizing beam splitter 9 is converted into a parallel beam by the objective lens 46, passes through the quarter-wave plate 45 again, and is returned to the polarizing beam splitter 44. By reciprocating the 1/4 wavelength plate 45, the plane of polarization of this laser beam is rotated by 90 degrees compared to when it passes through the polarizing beam splitter 44, and the plane of polarization is rotated by this 90 degrees. The rotated laser beam is reflected by the polarizing beam splitter 44 without passing through it. Then, the Lu+y light reflected by the polarizing beam splitter 44 is divided into two systems by a half mirror '47, and the laser beam of one of them (track deviation detection system) is transmitted to the first photodetector by the first projection lens 48. It will be irradiated on the 4th floor. On the other hand, the other side (
The laser beam of the defocus detection system) is located at the knife edge (
Only the components passing through a region separated from the optical axis are extracted by the light pumping member>50, and after passing through the second projection lens 51, are irradiated onto the second photodetector 52. Therefore, the light detection cells 52F1.52b, 49a, and 49b output signals corresponding to the irradiated light, and these signals are supplied to the amplifiers 61.62.71.72, respectively. As a result, the outputs of the amplifiers 71 and 72 are added by the adder circuit 79, and the result of this hl calculation is supplied to the binarization circuit 8o as a read signal (reproduction signal).

In such a state, the forcing operation when recording and reproducing information will be explained. That is, the signal from the amplifier 61 is amplified by the amplifier 63 and supplied to the differential amplifier 68. Further, the output from the amplifier 62 is supplied to a differential amplifier 64. At this time, the reference signal generation circuit 66 is supplied with the signal obtained from the control circuit 82 in the error rate check mode described above.

For this reason, the reference signal generation circuit 66 supplies, for example, a bias voltage of +2 volts to the differential amplifier 64 as a reference signal. As a result, the differential amplifier 64 outputs a signal obtained by adding a bias voltage to the signal supplied from the amplifier 62 to the differential amplifier 68.

Therefore, the differential amplifier 68 calculates the difference between the detection signal from the photodetection cell 52a and the signal obtained by adding a bias voltage (offset voltage) to the detection signal from the photodetection cell 52b. The drive circuit 70 supplies a predetermined current to the coil 54 in accordance with the signals from the six waveform shaping circuits, and outputs a signal corresponding to the objective lens to the drive circuit 70 via the six waveform shaping circuits. /46
is driven in the vertical direction to perform force thudding during recording. As a result, even if there is a mechanical positional deviation of the objective lens 46, the beam spot produced by the objective lens 46 during recording can be optimally positioned by correcting it using the bias voltage.

Furthermore, when the optical disc 19 of a song is changed or opened, the focal position of the objective lens may be changed to the optimal adjustment position as described above.

As mentioned above, since the pre-header 8 for several racks, that is, the same data, is regenerated by moving the focus position to determine the error rate 1, it is possible to prevent errors in determination from occurring. It is now possible to prevent even a single error from occurring on an optical disc. Furthermore, the error rate can be determined without adding special data to the optical disk 19. Furthermore, the error ray 1- can be set at the best position, and a wide margin for adjustment position deviation can be secured. I can do it.

[Effect of the invention 1 As detailed above, according to the present invention, the focal position can always be corrected to the optimal adjustment position without adding special data to the disk, and ■ the beam rate is improved and the adjustment is It is possible to provide a disk device that can have a wide margin against misalignment.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a block diagram showing the configuration of an image information storage and retrieval device, FIG. 2 is a plan view for explaining the configuration of an optical disc, and FIGS. FIG. 4 is a diagram strategically showing the configuration of the disk device, and FIG. 5 is a diagram for explaining the relationship between bias voltage and error rate. 1... Optical disk (disc), A... Block header (block header), 22... Optical disk device, 3
1... Optical head, 41... Light source (semiconductor laser)
, /16...Objective lens, 52...Second photodetector, 52a, 52b...Photodetection cell, 61.62...
Amplifier, 63.64.68...Differential amplifier, 65...
・Reference signal generation circuit, 69...Waveform shaping circuit, 70・
...Drive circuit, 80...Binarization circuit, 81...1 missing circuit, 82...Control circuit, 87...CRC check circuit, 88...Counter, 89...Storage circuit . Applicant's agent Patent attorney Takehiko Suzue = 34-

Claims (1)

[Claims] A disk device that records or reproduces information on a disk using focused light includes a light source, a focusing means for focusing light emitted from the light source onto the disk, and a focusing position on the disk by the focusing means. a determining means for determining an error rate using a pre-header recorded in at least one track on a disk for various focusing positions changed by the changing means; a storage means for storing an error rate of the storage means; a determination means for determining an optimal focusing position based on the error rate stored in the storage means; and a means for setting the focusing means at a focusing position corresponding to a determination result of the determination means. A disk device characterized by comprising: