JP2001202626A - Optical recording medium reader, signal processing circuit for reading optical recording medium and pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium reader which can be made inexpensive by simplifying the configuration for reading information on an optical recording medium while excluding the unstable factor of a conventional optical system mechanism. SOLUTION: This device is provided with an imaging device 22 for picking up pits in a prescribed area on an optical disk as an image by receiving the return light of a light beam for reproduction from the recording plane of the optical disk in pickup. Further, the device is provided with an image memory 32 for aligning image data, which are picked up for each prescribed angle by the imaging device 22, with the positions of pits, bonding and temporarily storing these data, an image recognizing block 34 for measuring individual pit lengths and pit intervals on the basis of these image data, a pit length data storage memory 35 for storing the information of these pit lengths and a virtual EFM signal generating block 36 for generating a virtual EFM signal similar to an EFM signal on the basis of this pit length information. Reproduced signals are obtained by performing demodulating processing of the virtual EFM signal in a signal processing part for reproducing the optical disk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CD-ROM,
The present invention relates to an optical recording medium reader for reading information on an optical recording medium such as a D-DA and a DVD, a signal processing circuit for reading an optical recording medium, and a pickup.

[0002]

2. Description of the Related Art As an optical recording medium, a disk-shaped recording medium such as a compact disk (CD) is widely used. For example, in an optical disk reading apparatus for reproducing an optical disk such as a CD-ROM, the recording is performed on the medium. When optically reading the read information, a light beam for reproduction by a semiconductor laser or the like is focused and irradiated on a target recording track to form a beam spot, and the light beam reflected from the medium (return light) ) Is received by a photodetector, and a read signal corresponding to the recorded information is generated based on the output.

In a conventional optical disk reading apparatus, means (focusing servo) for converging a light beam to a predetermined spot diameter so that the light beam appropriately traces a recording track on a medium having a pit array formed thereon, A means (tracking servo) for causing the light beam to follow a predetermined recording track (row of pits); a means (spindle servo) for controlling the reading speed from the recording medium by controlling the rotation of the recording medium (control of the spindle motor); Means (traverse servo) for moving a beam to a recording track at a predetermined position (seek or track jump) to access predetermined recording information has been used. By these means, pit information on the recording medium can be read without error.

FIG. 21 is a configuration explanatory view conceptually showing a configuration example of a conventional optical disk reader. The optical disk reading device includes a laser diode (LD) 101 that emits a laser beam for reading information, a half mirror 102, an objective lens 104 that focuses a light beam of the laser beam on the optical disk 103, and receives return light from the optical disk 103. A pickup having a photodetector (PD) 105 is provided. The pickup includes a focusing servo mechanism 106 including an actuator for displacing the objective lens 104 in the optical axis direction of the light beam, and an objective lens 10.
And a tracking servo mechanism 107 including an actuator for displacing the actuator 4 in a direction perpendicular to the optical axis of the light beam. Also, the optical disk reading device includes an optical disk 1
A spindle servo mechanism 108 that controls a spindle motor that rotationally drives the optical disk 1 and the optical disk 1
A traverse servo mechanism 109 for controlling a traverse motor that moves in the radial direction 03 is provided.

In the above-described configuration, the position of the light beam emitted from the objective lens 104 is controlled by operating each servo mechanism, and the position of the beam spot with respect to a predetermined recording track of the optical disk 103 and the focus of the light beam are adjusted. By doing so, it is possible to appropriately trace a predetermined pit row. The light beam of the laser light emitted from the laser diode 101 passes through the half mirror 102 and the objective lens 104 and is irradiated on the optical disk 103,
The return light from the optical disk 103 passes through the objective lens 104 and the half mirror 102, enters the photodetector 105, and is received. Then, a read signal based on the intensity of the return light from the optical disc 103 is obtained based on the output signal (RF signal) photoelectrically converted by the photodetector 105. The RF signal is digitized and demodulated by a signal processing semiconductor (DSP or the like) (not shown) at the subsequent stage, whereby a reproduction signal of information recorded on the optical disc 103 is generated, and reading of reproduction data is realized. .

[0006]

In the above-mentioned conventional optical disk reading apparatus, a focusing servo and a tracking servo must be provided in an optical reading system such as a pickup, so that the structure of these servo mechanisms becomes complicated. And a dedicated servo processing circuit for controlling each servo mechanism is required. Also, a control microcomputer (device controller) that controls the servo processing circuit
Software had to be designed according to complicated control procedures. Further, in the conventional device configuration, since the lens for focusing needs to be physically moved up and down, the actuator of the control mechanism is electromagnetically floated in the space, so that the read signal is interrupted by a disturbance such as an impact. There was something. As described above, in the conventional optical recording medium reading device, the device configuration becomes large and complicated,
It is difficult to reduce the cost of the apparatus, and there is a problem that the reproduction signal may be interrupted or an error may occur due to an unstable factor in the optical system mechanism.

The present invention has been made in view of the above circumstances, and can simplify the configuration for reading information from an optical recording medium, and can reduce the cost while eliminating the instability factor of the conventional optical system mechanism. An object of the present invention is to provide a possible optical recording medium reading device, an optical recording medium reading signal processing circuit, and a pickup.

[0008]

An optical recording medium reading apparatus according to the present invention captures a recorded information image in a predetermined area including pits, which are optically readable information recording areas formed on a recording surface of a recording medium. Imaging means, image storage means for storing image data of the optical recording medium recording surface obtained by the imaging means, and pit length information including pit lengths and intervals on the optical recording medium based on the image data And a read signal generating means for generating a virtual read signal corresponding to the pit read signal based on the pit length information.

Preferably, an optical disk which is a disk-shaped medium is used as the optical recording medium, and the imaging means obtains a captured image by imaging recorded information images including pits on the optical disk at predetermined angles. And As an optical recording medium, not only an optical disk but also an optical card or the like can be applied.

The image pickup means is, for example, a CCD or a MOS.
It is configured using an image sensor such as an image sensor, and is mounted in a reading pickup or the like.

Preferably, the image processing apparatus further includes a binarizing unit for binarizing the captured image obtained by the imaging unit, and the image storage unit stores the binarized image data.

Preferably, the apparatus further comprises a pit length information storage means for sequentially storing the pit length information obtained by the pit length information detection means in accordance with a pit string.

The read signal generating means uses, for example, pit length and pit interval data as pit length information to generate a read signal corresponding to the detection result of the arrangement of pit rows recorded on the optical recording medium. Generate an alternative virtual read signal.

Preferably, a signal processing circuit including the image storage means, the pit length information detection means, and the read signal generation means is mounted on a single semiconductor chip.

Alternatively, a second semiconductor circuit on which a signal processing circuit including the image storage unit, the pit length information detection unit, and the read signal generation unit is mounted, demodulates the virtual read signal. It is assumed that a second semiconductor circuit including a signal processing circuit is connected.

Alternatively, a first signal processing circuit including the image storing means, the pit length information detecting means, and the read signal generating means, and a second signal processing circuit for demodulating the virtual read signal are provided. It is assumed that they are integrally mounted on a semiconductor chip.

In the case where the signal processing circuit up to the read signal generation means and the signal processing circuit for demodulating the virtual read signal at the subsequent stage are formed separately, if the signal processing circuit at the subsequent stage is generally used as a signal processing circuit at the subsequent stage, it is used for reproducing an optical disk. It becomes possible to use a signal processing circuit. In addition, when the signal processing circuit up to the read signal generation means and the signal processing circuit for demodulating the virtual read signal at the subsequent stage are integrally configured, the semiconductor circuit and the device can be reduced in size and integrated. Circuits can be reduced as
The device configuration can be simplified.

A signal processing circuit for reading an optical recording medium according to the present invention is obtained by imaging a recorded information image of a predetermined area including a pit, which is an optically readable information recording area formed on a recording surface of an optical recording medium. Image storage means for storing image data of the recording surface of the optical recording medium, and pit length information detection means for obtaining pit length information including pit length and interval on the optical recording medium based on the image data, Read signal generating means for generating a virtual read signal corresponding to the read signal of the pit based on the pit length information,
It is characterized by having.

According to the present invention, there is provided an optical recording medium reading pickup, comprising: a light source for generating a light beam for irradiating the optical recording medium; and a return light of the light beam on the optical recording medium. An image pickup element for picking up a recorded information image of a predetermined area including a pit, which is an optically readable information recording area formed on a recording surface, and a light beam from the light source guided to the optical recording medium; Light guiding means for guiding the return light of the light beam to the image pickup device,
It is characterized by having.

Preferably, the light guiding means has an expanding means for expanding a beam diameter of the return light of the light beam.

As the light source, for example, a semiconductor laser such as a laser diode is used.
D or a MOS image sensor is used. The light guide means includes, for example, a slit having a predetermined beam diameter for light emitted from a light source, a mirror or a half mirror for directing a light beam to a recording surface of an optical recording medium or an image sensor. For example, a concave lens, a plano-concave lens, a concave mirror, or the like is used as the enlarging means in the light guide means.

In the above configuration, since the image pickup means picks up an image of a pit row for each predetermined area on the recording surface of the optical recording medium to obtain pit length information, it is generally necessary for an optical recording medium reading apparatus. This eliminates the need for a focusing servo mechanism for adjusting the focusing state of the light beam spot. Further, the tracking servo does not need to precisely follow the light beam spot to the track of a specific pit row.

For this reason, it is possible to simplify the servo mechanism and its control system which require more advanced design technology, and to simplify the structure of the pickup including the optical system and to reduce the weight. By reducing the weight of the optical system, the vibration resistance performance of the device is improved. Further, since the optical system driving mechanism for servo is not required, the resistance to the impact of the pickup is increased, and stable operation can be always performed. As a result, it becomes possible to remove the instability factor of the conventional optical system mechanism, and to realize a reduction in the size, weight, and cost of the optical recording medium reader.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, as an example of an optical recording medium reading device, the configuration and operation of an optical disk reading device that optically reads information recorded on an optical disk that is a disk-shaped optical recording medium and obtains a reproduction signal will be described. Optical disks include not only read-only disks of emboss type (stamp type) such as CD-ROM, but also CD-R,
CD-RW, DVD-R, DVD-RW, DVD-RA
A dye-based writable disk such as M or a phase change disk can also be used. Although only an optical disk reader is illustrated here, the present invention is not limited to an optical disk, but is also applicable to an apparatus that reads another optical recording medium such as an optical card.

FIG. 1 is a structural explanatory view showing the structure of a pickup section of an optical disk reader according to one embodiment of the present invention.
FIG. 2 is a structural explanatory diagram showing a first structural example of an optical system inside the pickup, and FIG. 3 is a structural explanatory diagram showing a second structural example of the optical system inside the pickup.

The optical disk reader is shown in FIG.
As shown in (B), an optical disc 1 is used as an information reading system.
1, a pickup 13 for reading information (pit train) recorded on the recording surface of the optical disc 11, and a pickup 13 driven in the radial direction of the optical disc 11 to be positioned on a predetermined recording track. And a traverse motor 14 to be positioned.

FIG. 2 shows a first configuration example of the pickup.
The pickup 13 is provided with a light source for an information reading light beam by a semiconductor laser such as a laser diode (LD) 15, and emits a parallel beam emitted from the laser diode 15 in a predetermined shape in front of the laser diode 15. A slit 16 for shaping into a light beam 17 of a size (beam diameter) is provided. In the optical path of the light beam 17, a half mirror 18 that guides the light beam 17 to the optical disk 11, a mirror 19 that guides the return light of the light beam 17 from the optical disk 11 to the photodetector, and a return light of the light beam 17 A concave lens 20 for enlarging the beam diameter at a predetermined magnification;
And a convex lens 21 for converting the enlarged return light into a parallel beam again. Here, the reflectance of the half mirror 18 is about 50%, and the reflectance of the mirror 19 is about 100%.
And

Further, there is provided an image pickup device 22 for picking up and detecting recorded information in a predetermined area on the optical disk 11 as image information, and the optical disk 11 having passed through the optical system is provided.
The return light of the light beam 17 from the optical disk 11 is incident on the imaging surface of the imaging element 22, and an image of a predetermined area on the recording surface of the optical disk 11 is captured. As the imaging device 22, a CCD or a MOS imaging device is suitable, but the configuration is not limited. If the imaging device 22 can obtain two-dimensional image information, the cds may be formed into a two-dimensional array. Any of them can be used.

The light beam 17 emitted from the laser diode 15 passes through the slit 16 and is shaped into a predetermined shape and beam diameter. Then, the light beam 17 is reflected by the half mirror 18 and irradiated on the recording surface of the optical disk 11. The return light reflected by the optical disk 11 passes through the half mirror 18 and passes through the mirror 1
After being reflected at 9, expanded by a concave lens 20 and converted into a parallel beam by a convex lens 21, the light is incident on an image sensor 22, forms an image, is photoelectrically converted, and is output from the image sensor 22 as an image signal. In the present embodiment, the resolution of the image sensor 22 can be improved by expanding the beam diameter of the return light using the concave lens 20.

FIG. 3 shows a second configuration example of the pickup.
The pickup 13a of the second configuration example is provided with a concave mirror 23 instead of the concave lens 20 as a means for expanding a light beam. In the optical path of the light beam that has been reflected and expanded by the concave mirror 23, a convex lens 24 that makes the expanded return light a parallel beam again, and an imaging element 22 that captures and detects information recorded on the optical disk 11 as image information. Is provided. In this example, a light beam emitted from a laser diode 15 passes through a slit 16 and is shaped into a light beam 17 having a predetermined shape and beam diameter.
Then, the recording light of the optical disk 11 is transmitted through the optical disk 8. The return light reflected by the optical disk 11 is reflected by the half mirror 18.
Is reflected by the concave mirror 23, is reflected by the concave mirror 23, and the beam diameter is enlarged at a predetermined magnification. Although the optical path from the half mirror 18 to the concave mirror 23 and the optical path from the concave mirror 23 to the image sensor 22 appear to overlap in the illustration, the optical elements are actually arranged three-dimensionally so that the optical paths do not overlap. Have been.

As described above, various modifications can be considered for the configuration of the optical system of the pickup. Any device can be used as long as the image of the pit row recorded on the optical disk can be captured by the image sensor. If the resolution of the image sensor is high, it is also possible to adopt a configuration in which the return light of the light beam directly reflected by the optical disk is imaged without providing a light beam expanding means such as a concave lens. is there. In this case, since it is not necessary to provide a lens or the like, in some cases, it is possible to configure the pickup with only the laser light source and the imaging device, and the configuration can be further simplified.

In the optical system of the present embodiment as described above, since a parallel light beam is emitted from the pickup 13 toward the optical disk, even if the distance between the recording surface of the optical disk and the pickup fluctuates, the image sensor 22 Above, the same recorded information image is always obtained. For this reason, the focusing servo mechanism required conventionally can be omitted, and the configuration of the pickup can be simplified, downsized, and lightened. In this case, there is no need to provide a coil for electromagnetically driving the objective lens in the vertical direction and the horizontal direction, and it is possible to reduce the mass of the entire pickup and to provide excellent vibration resistance. Also, at the time of pickup movement operation at the time of data reading,
The effect of inertia is small, and stable operation can be realized.

FIG. 4 is a block diagram showing the configuration of the signal processing section of the optical disk reader. In the pickup having the above-described configuration, the image of the pit, which is a recording mark on the optical disk, is captured by the image sensor 22 as shown in FIG. Here, the case of an embossed optical disk such as a CD-ROM is shown. Differences between captured images of the embossed type and the dye type or phase change type optical disks will be described later.

The signal processing section at the subsequent stage of the image pickup device 22 includes a binarizing means corresponding to a binarizing means for binarizing a captured image signal.
A value processing block 31, an image memory 32 corresponding to an image storage means for temporarily storing binarized image data, an image memory management block 33 for controlling writing and reading of the image memory 32, An image recognition block (pit length measurement block) 34 corresponding to a pit length information detecting means for calculating data of a length (hereinafter referred to as a pit length) and a pit interval (hereinafter referred to as a pit interval); A pit length data storage memory 35 corresponding to pit length information storage means for storing information (hereinafter referred to as pit length information) is provided. The operations of the virtual EFM signal generation block 36, the pit length storage memory 35, and the virtual EFM signal generation block 36 corresponding to a read signal generation unit that generates a pseudo EFM signal (hereinafter, referred to as a virtual EFM signal) from the pit length information. Length readout management block 3 for controlling the memory
7, a timing generation block 38 for generating a timing signal for generating the virtual EFM signal, and an optical disk reproduction signal processing unit (CD signal processing LSI) 39 for generating a reproduction signal of the optical disk from the virtual EFM signal.

In this embodiment, the configuration of a signal processing unit for reproducing a CD-ROM, a music CD, and the like will be exemplified. Normally, in these CD-based optical discs, an EFM signal (signal by an 8-14 modulation code) is used as a modulation signal for information recording.
Is used, and a reproduction processing circuit reads and demodulates the EFM signal to obtain a reproduction signal. In a conventional apparatus, when reading recorded information on an optical disc, an EFM signal is obtained as an output signal (RF signal) from a photodetector of a pickup. In the present embodiment, a virtual EFM signal corresponding to the signal is processed by signal processing on a captured image. Generate.

The image signal of the optical disk recording surface imaged and output at predetermined timings by the image pickup device 22 is binarized by a binarization processing block 31 and converted into digital image data, which is temporarily stored in an image memory 32. Is done. With the analog image information of multiple colors obtained by the image sensor,
Since a large amount of memory is required for signal processing, it is sufficient to detect the presence or absence of pits.
The value is converted into a value and the brightness level (brightness level) is stored as a binary value. In the image memory management block 33, the image memory 32
Control of writing and reading of image data to and from the image data. Specifically, for each piece of image data discretely acquired for each predetermined angle of the optical disc, the image data is joined to adjacent image data so that the subsequent image recognition block 34 can be treated as an array of pit strings. Process and output.

Next, in the image recognition block 34,
The required pit length and pit interval data are calculated from the image data stored in the image memory 32, and these data are stored in the pit length data storage memory 35 as an ordered array. Then, the virtual EFM signal generation block 36
In step (1), a virtual EFM signal is synthesized from the pit length information stored in the pit length data storage memory 35 and output to the optical disk reproduction signal processing unit 39. At this time, the pit length memory read management block 37 controls the processing operations in the pit length data storage memory 35 and the virtual EFM signal generation block 36 based on the timing signal generated in the timing generation block 38. In the virtual EFM signal generation block 36, information for synchronization (for example, a synchronization pattern of 44.1 kHz) is searched from the pit length information, and the pit length information stored in the pit length data storage memory 35 is read out in order. A virtual EFM signal is generated for each predetermined unit.

This virtual EFM signal is equivalent to an EFM signal generated by a reproduction processing circuit for a general CD optical disk, and is a signal processing section 39 for optical disk reproduction at a later stage.
Can use the same configuration as the conventional one. The optical disk reproduction signal processing unit 39 performs demodulation processing of the virtual EFM signal, and obtains a reproduction signal as an output.

FIG. 5 is a block diagram showing a first configuration example when the signal processing unit of the present embodiment is mounted on a semiconductor chip. The reproduction signal processing semiconductor 42 includes the above-described binarization block 31, image memory 32, and image memory management block 3.
3. Electronic circuits for realizing each function including the image recognition block 34, the pit length data storage memory 35, the virtual EFM signal generation block 36, the pit length memory readout management block 37, and the timing generation block 38 are integrated in a semiconductor chip. Be composed. This reproduced signal processing semiconductor 42
The imaging device 22 and the imaging device control unit 41 are connected to the input unit of. The output section of the reproduction signal processing semiconductor 42 is connected to the above-described signal processing section 39 for optical disk reproduction, and the ECC decoder 4 is provided downstream of the signal processing section 39 for optical disk reproduction.
3 and the audio DA converter 44 are connected.

Under the control of the image memory management block 33 of the reproduction signal processing semiconductor 42, the image pickup device control section 41 controls the image pickup timing of the image pickup device 22, and the like.
The obtained image signal is input to the reproduction signal processing semiconductor 42, and the virtual EFM signal generation processing as described above is performed.
This virtual EFM signal is output to an optical disk reproduction signal processing unit 39 made of a separate semiconductor, where demodulation processing and the like are performed and output as a reproduction signal. In the case of digital data other than audio signal data, the reproduced signal is subjected to error correction processing and the like by the ECC decoder 43, and is transferred to a subsequent data processing unit (not shown).
In the case of audio signal data, the audio D
The audio signal is converted into an analog audio signal by the A-converter 44 and sent to an audio signal processing unit (not shown) at a subsequent stage.

FIG. 6 is a block diagram showing a second configuration example when the signal processing unit of the present embodiment is mounted on a semiconductor chip. The second configuration example is different from the first configuration example in that the reproduction signal processing semiconductor 42 and the optical disc reproduction signal processor 3
9 is an example in which a CD reproduction processing semiconductor 45 is integrally formed in the same chip. The configuration of the other parts is the same as that of the first configuration example. As in the first configuration example, an optical disc reproduction signal processing unit 39 having the same general-purpose configuration as the conventional one.
May be provided externally to integrate only the functional configuration of the preceding stage, or as in the second configuration example, the reproduction signal processing semiconductor 42 and the optical disk reproduction signal processing unit 39 are integrally integrated. Then, it can be configured as a one-chip device. The mounting form of the semiconductor is not particularly limited.

FIG. 7 is a block diagram showing a third configuration example when the signal processing unit of this embodiment is mounted on a semiconductor chip. The third configuration example is a modified example in the case where the CD reproduction processing circuit is configured by a one-chip semiconductor. In the case of a one-chip configuration, the signal processing unit 3 for reproducing an optical disc is used as an output.
Since it is only necessary to obtain a reproduction signal similar to that in No. 9, it is not always necessary to generate a virtual EFM signal. Accordingly, a reproduction signal encoder 46 is provided in the output section, and a CD reproduction processing semiconductor 47 is configured to directly generate and output a reproduction signal from the pit length information stored in the pit length data storage memory 35. . An ECC decoder 43 and an audio DA converter 44 are directly connected to the subsequent stage. The configuration of the other parts is the same as that of the first configuration example.

In the third configuration example, the pit length information stored in the pit length data storage memory 35 is read and the signal is synthesized based on the timing signal from the timing generation block 38 under the control of the pit length memory read management block 37. Processing and the like are performed, and a final reproduction signal is generated and output from the CD reproduction processing semiconductor 47.

In the first configuration example, since the signal processing circuit for reproducing a general optical disk can be used as it is and can be combined, the present embodiment is applied to the conventional apparatus with a minimum design change. It is possible. Further, the degree of freedom of the device configuration is high. On the other hand, in the second and third configuration examples, since the main part of the signal processing circuit for CD reproduction can be formed of a one-chip semiconductor, the size of the device can be further reduced, and the effect of cost reduction by mass production is great. . In the third configuration example, since the configuration of the signal processing circuit can be simplified, the size can be further reduced.

Next, a CCD is used as the image pickup device 22,
Examples of captured images when an embossed optical disk such as a CD-ROM is used as the optical disk 11 and when a dye-based or phase-change optical disk such as a CO-R is used are shown. FIG. 8 is an explanatory view showing a recording surface of an embossed optical disk and a corresponding image of a CCD imaging surface, and FIG. 9 is a recording surface of a dye-based or phase-change optical disk and an image of the corresponding CCD imaging surface. FIG.

Currently available CCD image pickup devices, for example, of the 2 million pixel class, have a CCD pixel size of about 4 μm. In order to accurately read out the pit width, pit length, and pit interval on the optical disc, for example, since the pit width of a CD is about 0.4 μm, it is necessary to enlarge the beam diameter by about 100 times as an optical system. To read pit information. In the pickup configuration of FIG. 1, the enlargement unit including the concave lens 20 enlarges about 100 times. As a result, the enlarged pit image is projected on the imaging surface of the CCD, and it is possible to capture an image with a sufficient resolution, and appropriate pit length information can be obtained by signal processing in the subsequent stage.

As shown in FIGS. 8A and 8B, in an embossed optical disk, a pit 52 is formed in a land 51 by a method such as stamping. The edge portion of the pit 52 has a physical inclination, and when irradiated with a light beam, the reflection direction of the incident light changes at this inclined portion and deviates from the optical path toward the image sensor. That is, when viewed from the image sensor, the return light at the edge portion of the pit becomes a darker shade 53 than the land portion, and an image representing the contour of the pit is projected on the pixel 54 of the image sensor. By utilizing this property, an image including pit outline information is captured.

On the other hand, as shown in FIGS. 9A and 9B, a land 55
There is no unevenness between the portion of the pit and the portion of the pit 56. For example, when writing information on a CD-R using an organic dye,
By changing the composition of the organic dye due to the high temperature of the laser beam, the pit 56 is recorded by lowering the light reflectance. In a phase-change type such as a CD-RW, a pit 56 having a low light reflectance is recorded by destroying a phase (crystal structure or orientation) of a substance by a high temperature of a laser beam. When these are viewed from the image sensor, the return light in the pit portion becomes a darker shade 57 compared to the land portion,
An image representing the shape of the pit is projected on the pixel 58 of the image sensor. By utilizing this property, an image including pit shape information is captured.

FIG. 10 is an explanatory diagram showing filter processing for enabling two types of picked-up images obtained respectively from an embossed optical disk and a dye-based or phase-change optical disk to be processed by the same signal processing circuit at the subsequent stage. It is.

A captured image 62 obtained when an embossed optical disk such as a CD or CD-ROM is used is output to the binarization processing block 31 as a processing image 64 having only pit outlines. On the other hand, a captured image 61 in the case of using a dye-based or phase-change optical disk such as a CD-R,
The image signal is subjected to differentiation processing by the image processing differentiation filter 63 and converted into an image in which the outline of the pit is extracted, and is then output to the binarization processing block 31 as a processing image 64. This filter processing unit may be provided on either the pickup side or the signal processing unit side. In practice, image recognition of the captured image is performed to determine whether the pit portion is only the outline or the whole. If the image is the entire pit portion, only the outline portion is extracted using the image processing differential filter 63. By such a filtering process, the captured images of the two types of optical disks can be handled in the same manner, and the pit can be read regardless of the type of the optical disk.

Next, a method of storing a captured image in the memory will be described. FIG. 11 is an explanatory diagram showing an imaging range of the imaging element 22 and a reading range used for actual reading.

The signal processing circuit after the binarization processing block 31 uses the image signal of the reading range 66, which is a narrower range, for the imaging range 65 obtained by the imaging device 22, and generates the pit length information. Performs reproduction signal processing such as detection. The data outside the read range 66 is used in the image memory management block 33 as an area for judging coincidence or non-coincidence when joining adjacent images, and at the same time, for fine adjustment of the eccentricity of a disc-shaped recording medium. Also used as an area.

Image signals (image data) taken at predetermined angles of the optical disk 11 by the image pickup device 22 are temporarily combined in the image memory 32 to join the images to form one large recording surface image. It is written with At this time, the images of the pits on the recording surface, which are relatively circularly traced by the pickup on the disk surface and imaged, are joined in a linearly extended form and stored in the image memory 32.

As a method of joining images, for example, FIG.
The pattern of the pit part (dark part) and the part other than the pits (light part) such as lands at the boundary between the read range 66 and the non-effective area outside the range are analyzed, and the pattern coincides with the image data to be connected. A joint is realized by using a means for judging the connection position by using a means for storing and managing the imaging order of the imaging data. These image joining processes are performed as shown in FIG.
Memory management block 3 on the image memory 32
This is executed under the control of No. 3.

Here, an example of correction processing for eccentricity of the optical disk will be described. In the present embodiment, the mechanical correction means for driving the pickup 13 by the traverse motor 14 and the electric correction means for performing the joining process of the picked-up images are combined to provide a coarse eccentricity correction covering a wide range and a small range. Fine eccentricity correction is performed so as to cope with large eccentricity that may occur in an actual optical disc. FIG. 12 is a block diagram illustrating a configuration example of the eccentricity correction unit.

The eccentricity correction means of this configuration example includes an eccentricity control unit 71 for controlling an eccentricity correction operation,
Synchronization sign signal generating section 72 for generating a synchronization sign signal synchronized with the disk rotation from the FG pulse indicating the rotation state of
A drive signal generator 73 for generating a drive signal for the traverse motor 14 by superimposing a synchronous sign signal on the image data read from the image memory 32;
And a motor drive control unit 74 that performs the above control.

FIG. 13 is an explanatory diagram of the electrical eccentricity correction processing in the image memory 32. The image memory 32 analyzes the pattern of the dark part and the light part of the adjacent captured images when joining and storing the captured images as described above, and determines the effective area (corresponding to the reading area 66) based on the analysis result. Images are connected by shifting by the eccentric amount d. For example, the imaging range 75a,
When connecting the captured images of 75b and 75c, electrical eccentricity correction is performed by determining and connecting the effective areas of the respective images as effective areas 76a, 76b and 76c from the pattern analysis results. Therefore, a slight positional shift of the captured image due to the eccentricity of the optical disk or the like can be absorbed by the electric eccentricity correction in the image joining processing.

For example, in the case of a CD, the eccentricity of a standard disc is up to 70 μm, but the actual eccentricity is such that the disc is mechanically mounted on a spindle motor 12 for rotating the optical disc 11. Therefore, in consideration of the chucking error and the accuracy of a commercially available disk, it is necessary to assume about 350 μm. With respect to such a large eccentricity, the pickup 1
3 is displaced in the radial direction of the optical disk 11 by using mechanical correction means.

The operation of the mechanical eccentricity correcting means will be described below. 14 is an explanatory diagram showing a traverse motor correction signal for eccentricity correction, FIG. 15 is a flowchart showing a procedure of an eccentricity amount detection process, and FIG. 16 is a flowchart showing a procedure of an eccentricity correction process.

When the optical disk 11 is mounted (mounted on the spindle motor 12) (step S1 in FIG. 15).
1), the eccentricity control unit 71 moves the pickup 13 to the inner circumference of the optical disk 11 (step S12), and determines whether or not an area without a pit row on the innermost side (hereinafter, referred to as a mirror area) is found. (Step S13) This process is repeated to move the pickup 13 to the mirror area.
Then, the mirror area of the optical disk and the innermost edge of the pit row are imaged for one round so that the innermost end face of the pit row falls within the imaging range, and this image data is stored in the image memory 32.
(Step S14). Then, based on the acquired image data, the right end (or left end) of the imaging range of each image
The distance information from the rotation center axis of the optical disk to the end face of the pit train is obtained by measuring the distance from the pit train to the innermost peripheral edge of the pit train (step S15). Then, based on the obtained distance information, the amount of physical eccentricity is calculated by subtracting the minimum value from the maximum value, and stored in a memory (not shown) inside or outside the eccentricity control unit 71 (step S16).

Here, the method of calculating the physical eccentricity is shown in FIG.
3 will be described. The three images in the figure are images of a continuous disk surface, and indicate that the captured image is shifted in the disk radial direction (left and right direction in the figure) due to eccentricity. From the information of the dark part (the part with the pit) and the bright part (the part without the pit) in the image data stored in the image memory 32, the innermost peripheral position boundary where the pit row exists is detected from the memory address, respectively. The displacement of the innermost peripheral end of the pit row is calculated. The maximum value of the deviation can be obtained by searching the deviation data for one round of the disk, and the maximum physical eccentricity can be obtained from the maximum value of the deviation.

When the physical eccentricity is detected, rotation information such as the rotation speed of the optical disk 11 can be obtained by the FG pulse output from the spindle motor 12.
As shown in FIG. 14, the amount of eccentricity changes in a cycle of one rotation of the disk. Therefore, as a reference signal for eccentricity correction, a synchronous sine signal synchronized with the FG pulse is generated in the synchronous sine signal generator 72 (step S2 in FIG. 16).
1). This synchronization sign signal is a periodic signal that has one cycle corresponding to one rotation of the disk. Subsequently, the correction signal generation unit 73 multiplies the maximum physical eccentricity obtained as described above as a coefficient by the synchronous sine signal to generate a traverse motor correction signal as a voltage signal (step S22). And
The generated traverse motor correction signal is input to the motor drive control unit 74, and the eccentric component is canceled by feedforward. As a result, a drive signal acting to cancel the eccentricity of the optical disk 11 is supplied to the traverse motor 14.

By driving the traverse motor 14 in this manner, the pickup is moved to displace the imaging range itself, and the eccentricity of the optical disk is corrected (step S23). Thereafter, it is determined whether or not an abnormal state such as a failure to join the captured images has occurred (step S24).
If no abnormal condition is detected, the process waits for a predetermined time (step S25), and repeats these processes to continue the abnormal condition detecting operation. If an abnormal state has occurred, the flow returns to step S21 to execute the eccentricity correction processing again.

In this embodiment, the eccentric component can be effectively canceled over a wide range by moving the imaging range in synchronization with the eccentricity of the disk. Further, by using the above-described electric eccentricity correction means together, it is possible to stably and appropriately remove the eccentricity component. In addition, since the mechanical correction means has excessive behavior with respect to minute fluctuations, when the amount of eccentricity is within a predetermined range, the effective range in the imaging range of the image sensor described above is moved to reduce the eccentricity component. The eccentricity correction operation can be switched so that only the electrical correction means to be removed is used.

Next, a method of calculating pit length information will be described with reference to FIGS. FIG. 17 is an explanatory diagram showing a model of a method of storing image data in an image memory, FIG. 18 is an explanatory diagram for explaining a method of calculating a pit length, and FIG. 19 is a diagram showing a method of storing pit length information in a pit length data storage memory. FIG. 20 is an explanatory view showing a model, and FIG. 20 is an explanatory view showing a signal processing procedure for obtaining a reproduction signal from pit length information.

As described above, the image data 81 of the picked-up image on the optical disk recording surface, which is picked up by the image pickup device 22 at a predetermined angle and binarized by the binarization processing block 31, as shown in FIG. In the image memory 32, a joining process is performed according to the imaging position and stored. At this time, in the image memory management block 33, the image acquisition position, the possibility of joining with the previously acquired image data, the connection order, and the like are managed. These management information and memory addresses are associated with the image data and Is stored. Here, by performing the joining process and managing the joining information,
The processing load on the image recognition block 34 and the pit length data storage memory 35 for measuring the pit length at the subsequent stage is reduced.

The image data stored in the image memory 32 is appropriately read out under the control of the image memory management block 33, and the length Lp and pit interval Li (see FIG. 18) of each pit are measured in the image recognition block 34. You.
The obtained pit length Lp and pit interval Li are sequentially stored as pit length information 82 in the pit length data storage memory 35 as shown in FIG. At this time, the image data in the image memory 32 has already been binarized, and the results of measuring the lengths and intervals of the light and dark portions in the vertical direction (track direction of the disk) in the figure on the time axis are used as pit length information. To convert.

That is, the light receiving intensity of each data corresponding to the minimum pixel of the image sensor 22, that is, the intensity data of the return light, is used to determine a bright portion and a dark portion based on a predetermined detectable threshold value. And an image memory 3 in which data of this boundary is stored.
The pit length Lp and the pit interval Li are obtained from the address 2.

The pit length information is extracted as a one-dimensional data string for each pit string, and a plurality of pit strings in the image data are handled as a data array, so that the pit length information of the plurality of pit strings is simultaneously obtained. It is stored in the long data storage memory 35. At this time, in the pit length data storage memory 35, pit length information of a continuous pit row is sequentially packed and stored in a continuous memory address, and pit length information of another pit row extracted from the same image data is stored in another memory address. Are stored successively.

The pit length information 82 stored in the pit length data storage memory 35 is sequentially read out in memory address order under the control of the pit length memory read management block 37. Then, a synchronization signal which is a specific combination of the pit length and the pit interval is searched, and in the virtual EFM signal generation block 36, each pit length and the pit interval are faithfully synchronized with the timing signal generated by the timing generation block 38. Reproduce. The digital signal generated here is a modulated signal that can be processed by a general signal processing circuit that performs demodulation processing of the optical disc. In the present embodiment, an EFM obtained by reading a CD optical disc
A virtual EFM signal similar to the signal is generated. Then, a demodulation process of the virtual EFM signal is performed in the optical disc reproduction signal processing section 39, and a reproduction signal of the optical disc is output.

In this case, the virtual EFM signal generation block 3
6, a virtual EFM signal similar to the EFM signal is output, so that the signal processing circuit 39 for the optical disk reproduction can use a signal processing circuit using the existing technology as it is. That is, in the optical disk reading device, E
The present embodiment can be configured by replacing the configuration up to the portion that outputs a digitized read signal such as an FM signal with a conventional configuration.

As described above, in this embodiment, since the image pickup device picks up an image of a pit row for each predetermined area on the optical disk and obtains pit length information, the in-focus state of the light beam spot is determined. The need for a focusing servo mechanism to adjust is eliminated. Further, the tracking servo does not need to precisely follow the light beam spot to a specific track. For this reason, it is possible to simplify the servo mechanism and its control system that require more advanced design technology, simplify the configuration of the pickup including the optical system, and reduce the weight. If the weight of the optical system is light, the vibration resistance performance is improved. In addition, since the driving part of the optical system does not exist in the pickup, there is no part that is mechanically damaged even when an impact is applied. Therefore, there is an advantage that the impact resistance is high and a stable operation can always be performed.

Further, according to the present embodiment, it is possible to provide an electronic reading device in which mechanical components are eliminated, so that if an expensive imaging device is reduced in price at present, further cost reduction can be realized. Furthermore, in the current imaging device, the resolution is not enough for the recording density to directly image the pits of the optical disc, but if the integration of the imaging device is advanced in the future and a high-resolution one can be used, An optical element such as a concave lens used as a light beam expanding means can be omitted. In this case, since the pickup can be configured with only the minimum components such as the laser light source and the image pickup device, further reduction in size, weight, and cost can be achieved.

[0074]

As described above, according to the present invention, the configuration for reading information from an optical recording medium can be simplified, and the cost can be reduced while eliminating the instability factor of the conventional optical system mechanism. There is an effect that a simple optical recording medium reading device can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory diagram showing a configuration of a pickup unit of an optical disk reading device according to an embodiment of the present invention.

FIG. 2 is a configuration explanatory diagram showing a first configuration example of an optical system inside a pickup.

FIG. 3 is a configuration explanatory view showing a second configuration example of the optical system inside the pickup.

FIG. 4 is a block diagram illustrating a configuration of a signal processing unit of the optical disc reader.

FIG. 5 is a block diagram showing a first configuration example when the signal processing unit of the present embodiment is mounted on a semiconductor chip.

FIG. 6 is a block diagram showing a second configuration example when the signal processing unit of the present embodiment is mounted on a semiconductor chip.

FIG. 7 is a block diagram showing a third configuration example when the signal processing unit of the present embodiment is mounted on a semiconductor chip.

FIG. 8 is an explanatory diagram showing a recording surface of an embossed optical disk and a corresponding image on a CCD imaging surface.

FIG. 9 is an explanatory diagram showing a recording surface of a dye-based or phase-change type optical disk and a corresponding image of a CCD imaging surface.

FIG. 10 is an explanatory diagram showing a filter process for enabling two types of picked-up images obtained respectively from an embossed optical disk and a dye-based or phase-change optical disk to be processed by the same signal processing circuit at the subsequent stage. .

FIG. 11 is an explanatory diagram illustrating an imaging range of an imaging element and a reading range used for actual reading.

FIG. 12 is a block diagram illustrating a configuration example of an eccentricity correction unit.

FIG. 13 is an explanatory diagram of electrical eccentricity correction processing in an image memory.

FIG. 14 is an explanatory diagram showing a traverse motor correction signal for eccentricity correction;

FIG. 15 is a flowchart illustrating a procedure of an eccentricity amount detection process.

FIG. 16 is a flowchart illustrating a procedure of an eccentricity correction process.

FIG. 17 is an explanatory diagram showing a model of a method of storing image data in an image memory.

FIG. 18 is an explanatory diagram illustrating a method of calculating a pit length.

FIG. 19 is an explanatory diagram modeling and showing a method of storing pit length information in a pit length data storage memory.

FIG. 20 is an explanatory diagram showing a signal processing procedure for obtaining a reproduction signal from pit length information.

FIG. 21 is a configuration explanatory view conceptually showing a configuration example of a conventional optical disk reading device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Optical disk 12 Spindle motor 13 Pickup 14 Traverse motor 15 Laser diode (LD) 22 Image sensor 31 Binarization block 32 Image memory 33 Image memory management block 34 Image recognition block 35 Pit length data storage memory 36 Virtual EFM signal generation block 37 Pits Long memory read management block 38 Timing generation block 39 Optical disc playback signal processing unit

Claims (10)

[Claims] 1. An image pickup means for picking up a recorded information image of a predetermined area including a pit, which is an optically readable information recording area formed on a recording surface of an optical recording medium, and an optical recording obtained by the image pickup means Image storage means for storing image data of a medium recording surface; pit length information detection means for obtaining pit length information including pit lengths and intervals on the optical recording medium based on the image data; An optical recording medium reading device, comprising: read signal generating means for generating a virtual read signal corresponding to the pit read signal based on 2. An optical disk, which is a disk-shaped medium, is used as the optical recording medium, and the imaging unit obtains a captured image by capturing recorded information images including pits on the optical disk at predetermined angles. The optical recording medium reader according to claim 1. 3. The image processing apparatus according to claim 1, further comprising: a binarizing unit for binarizing a captured image obtained by the imaging unit, wherein the image storage unit stores the binarized image data. An optical recording medium reader according to claim 1. 4. The optical recording medium reading device according to claim 1, further comprising pit length information storage means for sequentially storing pit length information obtained by said pit length information detection means in accordance with a pit string. 5. The light according to claim 1, wherein a signal processing circuit including the image storage unit, the pit length information detection unit, and the read signal generation unit is mounted on one semiconductor chip. Recording medium reader. 6. A second semiconductor device that performs a demodulation process of the virtual read signal on a first semiconductor circuit mounted with a signal processing circuit including the image storage unit, the pit length information detection unit, and the read signal generation unit. 2. The optical recording medium reading device according to claim 1, wherein a second semiconductor circuit including a signal processing circuit is connected. 7. A first signal processing circuit including the image storage unit, the pit length information detection unit, and the read signal generation unit, and a second signal processing circuit that performs demodulation processing of the virtual read signal. 2. The optical recording medium reader according to claim 1, wherein the optical recording medium reader is integrally mounted on a semiconductor chip. 8. An optical recording medium recording surface image data obtained by imaging a recording information image of a predetermined area including a pit which is an optically readable information recording area formed on the recording surface of the optical recording medium. Image storing means for storing; pit length information detecting means for obtaining pit length information including pit lengths and intervals on the optical recording medium based on the image data; and reading of the pits based on the pit length information A signal processing circuit for reading an optical recording medium, comprising: read signal generating means for generating a virtual read signal corresponding to a signal. 9. A light source for generating a light beam for irradiating an optical recording medium, receiving a return light of the light beam on the optical recording medium,
An imaging element for capturing a recorded information image of a predetermined area including a pit, which is an optically readable information recording area formed on a recording surface of the optical recording medium; and guiding a light beam from the light source to the optical recording medium. An optical recording medium reading pickup, comprising: light guide means for guiding return light of the light beam on the optical recording medium to the image sensor. 10. The optical recording medium reading pickup according to claim 9, wherein said light guiding means has an enlarging means for enlarging a beam diameter of the return light of said light beam.