JPH04117626A - Optical information device and optical information recording member - Google Patents

Abstract

PURPOSE:To allow the reproduction of an optical disk having an arbitrary reflectivity by most adequately selecting the gain of a reproducing system at the time of signal reproduction from the optical disk. CONSTITUTION:A light source driving means B for maintaining the specified output of a light source 4, an optical means 4 which introduces the light from the light source 4 and condenses the light onto a recording medium 2, a photodetecting means 8 which receives the reflected light from the recording medium 2 and converts this light to an electric signal, an amplifying means 11 which amplifies the electric signal and sets the amplification factor at plural values, a control means 3 which drives the optical means A according to the amplified signal and executes focus control or tracking control, and an identifying means 15 which identifies the reflectivity of the recording member 2. The amplification factor of the amplifying means 11 is changed according to the result of the identification of the identifying means 15 and the amplification factor of the reproducing system C is most adequately set. The reproducing of the plural optical disks 3 varying in the reflectivity is executed in this way.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an optical information recording device and a recording member that store a large amount of information using a laser beam or the like. Optical information recording members (hereinafter also referred to as optical disks) that record information by forming differences in the optical state of parts, and technologies for recording or reproducing information on recording members are already known, and the first is the compact disc. (hereinafter abbreviated as CD) or a playback-only type represented by a laser disc.The second type is a document file/lz,
A write-once type that is applied to data files, etc.
Thirdly, a rewritable type with an erasing function is an optical disc C that is only for AM playback.It has a structure in which uneven pits corresponding to information signals are formed on the surface of the substrate, and a reflective layer made of a metal layer is provided on the surface of the substrate. Even so, when light is irradiated onto this optical disc, the reflectance of the metal layer is shown in the flat area, and the amount of reflected light decreases in the pit area due to diffraction of the irradiated light.By detecting this change in reflectance, the information on the disc is On the other hand, for write-once or erasable optical disks ζ, a metal thin film, chalcogenide thin film, organic yeast A, ferromagnetic thin film, etc. is provided on the substrate, and the thin film is heated by light irradiation, and the heated part changes state 4L shape change or magnetic Information is recorded or rewritten using changes in anisotropy.

Problems to be Solved by the Invention Although the three types of optical discs mentioned above have different configurations depending on their playback principles and functions, for example, a playback-only type may have a different configuration.Is it desirable that the light usage efficiency during playback be high? The reflectance of the recording layer is as large as possible -
More than 70% of them are used for boat fishing.4-X
Recording is performed by raising the temperature of the recording thin film to a certain level by the light irradiated during recording.There is so-called heat mode recording.Heat mode recording thin film light during recording Even though they are designed to exhibit high absorption for the wavelength of the irradiated light, for the above reasons, the reflectance of general write-once and rewritable optical discs is 20 to 40%, making them a read-only type. If you try to play back optical discs with different reflectances using the same optical disc device, the level of the focus signal, tracking signal, or other servo signal or playback signal obtained by the reflected light from the recording layer of the disc will be extremely low. Even if there is a significant difference, for example, the number of equipment that plays playback-only discs!
When equipped with a rewritable disc, the ribo signal is so small that it is difficult to even focus on the recording surface of the disc. In view of this, the present invention aims to provide an optical disk device and an optical disk that can play a plurality of optical disks with different reflectances. An optical information device for reproducing information signals recorded on an optical recording member, comprising a light source, a light source driving means having a function of keeping the output of the light source constant, and a recording medium for transmitting the light from the light source to the recording medium. an optical means having a function of guiding and condensing light upward; a light detection means having a function of receiving reflected light from the recording medium and converting it into an electric signal; and a function of amplifying the electric signal, and having a plurality of amplification factors. an amplification means having a function that can be set to different values; a control means for driving the optical means according to the amplified signal to perform focus control or tracking control; and an identification means for identifying the reflectance of the recording member. The second means includes a light source and a function for keeping the output of the light source constant, and the second means has a function of keeping the output of the light source constant, and the second means has a function of keeping the output of the light source constant, and the second means has a function of keeping the output of the light source constant, and the second means has a function of keeping the output of the light source constant, A light source driving means having a function that can be set to different values, an optical means including a function of guiding and condensing light from the light source onto a recording medium, and receiving reflected light from the recording medium and generating an electrical signal. an amplification means having a function of amplifying the electric signal; a control means for driving the optical means according to the amplified signal and performing focus control or tracking control; an identification means for identifying reflectance; the actuating light recording medium is also identified by changing the output of the light source driving means according to the identification result of the identification means; and a plurality of gains are set according to the identification result. It is possible to optimally set the amplification factor of the reproduction system or the irradiation power of the light source by using a possible amplification means or an optical drive means that can set multiple powers. On the other hand, it becomes possible to adjust the signal level to a predetermined range, it becomes possible to control the reproduction, and it is also possible to suppress the occurrence of reproduction errors during information reproduction. A recording device for a recording member will be described with reference to the drawings, and FIG. 1 shows a configuration diagram of an optical information recording device having a function of determining light irradiation conditions of the present invention. This device (optical disk 2 rotated by a companion spindle motor 1, optical system A for condensing laser light onto the optical disk, optical drive unit for driving the light source &
It is composed of a reproduction control section C for reproducing information from an optical disk and controlling a light spot, and the operation of each circuit is managed by a controller 3. First, the basic operation of each part will be briefly explained, and then the method for determining the light irradiation conditions according to the present invention will be explained.
The material of the substrate 2a may be resin such as polymethyl methacrylate (PMMA) or polycarbonate (PC), or glass.The recording material 2b
It varies depending on the type of optical disc, such as a write-once rewritable type, but in the case of a read-only type, a bit consisting of unevenness corresponding to the information signal is formed on the surface of the substrate, and a metal such as AI or Au is formed on the surface of the substrate. This is a configuration in which materials are provided. In the case of write-once type, TePd0 or a dye material is provided, and in the case of rewritable type, it is a recording material 2b that records signals by utilizing phase change due to light irradiation.
bTa, InSb The recording materials used in the magneto-optical recording system include L;L, TbFeCQGdTbFe, etc.For the recordable or rewritable optical disks, light is irradiated near the information area where information is recorded. Optical system A (i) A semiconductor laser 4 is used as the light source, and the light from the semiconductor laser is collimated by a collimator lens 5 and transmitted through a half mirror 6. Although the objective lens 7 focuses the light onto the recording thin film 2b of the optical disc A to a spot diameter of about 1 μm, which is the wavelength limit, the reflected light from the recording thin film 2b passes through the objective lens 7 again and is transmitted by the half mirror 6. A part of the light is reflected and the light is incident on a photodetector 8 consisting of a plurality of divided photodiodes. aThe optical drive unit B controls the current flowing through the semiconductor laser by the laser drive circuit 10 so that the semiconductor laser 4 emits light with the power set by the power setting device 9.a
In addition, if necessary, the output of the semiconductor laser may be changed in stages according to the control signal from the controller 3, and the set current may also be changed. The servo section 12 converts the low frequency component of the signal from the preamplifier 11 into a control signal to drive the voice coil 13 that supports the objective lens 7, and performs focusing and tracking of the spot on the optical disk. As a result, the optical beam can be focused on a predetermined position on the optical disk by the control signal from the controller 3. On the other hand, the demodulation circuit 14 uses the high frequency component of the signal from the preamplifier 11 to focus the optical beam on the optical disk 2. The information signals from the bits or shading marks formed above are demodulated, and the gain C of these preamplifiers is configured to be switched according to the signal from the controller.
By detecting the DC component of the signal from the preamplifier 11, the reflectance from the recording thin film can be measured. ) Here, the GEL playback control unit C is composed of a preamplifier circuit that can set multiple amplification factors (gains), and the gain of the preamplifier that operates according to the disc is switched in stages.The basic operation is as follows: Optical disc 2 is set in the device. The semiconductor laser 4 is driven by the signal S3 indicating that it is in a rotating state, and emits light with a predetermined power.4 Next, the signal from the photodetector 8 is amplified by the preamplifier 11, and the servo section 12
Figure 2 shows an example of a preamplifier with switchable gain. The amplification factor (gain) of this circuit is determined by the ratio of the input resistor RO connected to the operational amplifier 16 and the feedback resistors R1 to Rn.
If the value of n is R1<R2<Rn, the gain of the amplifier can be increased as the contacts I)1, R2, and Pn of the switch 21 connected to each resistor are switched. The state in which only contact P1 is closed is called the first gain, and the state in which contact P2 is closed is called the second gain.For example, first, using the signal that has passed through the preamplifier circuit of the first gain, the voice coil is controlled by the servo circuit. In the case of a disk with a high reflectance, each circuit operates and the predetermined signal can be reproduced.However, if the reflectance of the optical disk is low (the amplitude of the obtained servo signal is small, and the detection limit of the circuit is If the servo circuit stops operating due to the following signal level: In a general playback device: At this point, it is determined that there is a disc error and the playback mode is canceled. However, here, a detection error signal indicating that the servo signal is below the detection limit is detected. S12 is sent to the controller 3, and the servo circuit is driven by the signal passed through the second gain preamplifier by the signal S31 from the controller. If the servo circuit does not operate even with the second gain, it can be handled by selecting an even higher gain.The method described above identifies the reflectance of the disk based on the operating state of the servo circuit. By switching the gain of the preamplifier as described above, the amplification factor of the reproduced signal amplitude also changes according to the reflectance, and the signal demodulation level can be set within a predetermined range. Results For a disc exhibiting an arbitrary reflectance, it is possible to adjust the signal level within a predetermined range by always performing appropriate amplification (Example 2) This reproduction method Table 1 Figure 1 This method uses an irradiation power setting device 9 between the laser drive unit 10 and the controller 3 shown in FIG. The servo circuit is operated by driving the power setting device 9 and irradiating the optical disk with the light of the first power from the semiconductor laser.As a result, a servo signal is detected from the servo unit 12 as in the first embodiment. error 812
If this occurs, the signal from controller 3 will cause the first
A second power higher than the power is set by the power setting device 9, and servo control is performed again. By changing the irradiation power according to the disc in this way, it is possible to focus the amount of light reflected from the optical disc within a certain range. If it is 1mW (fS reflectance 4
Power 1; L2mW to irradiate 0% rewritable disc
With this configuration, it is possible to play back optical discs with any reflectance without changing the playback control circuit and with a simple structure of providing power setting devices in all stages of the laser drive section. a (Example 3) This reproducing method is a method in which an identification part is provided in advance at a specific location on the optical disc and the reproducing conditions are determined according to the identification result. A disc identification signal is recorded in the vicinity of the information area of the optical disc that is being used.Figure 3 (a)
11 A case is shown in which a disc identification signal 32 is formed on the inner circumference of the information area 31. As an identification signal, a bit signal on unevenness should be provided.Alternatively, guide grooves for tracking used in recordable and rewritable disks should be provided intermittently.The pattern of the grooves can be used to determine the type of disk, that is, the reflectance The above configuration method can be easily realized using the conventional process of simply adding an operation to record an identification signal at the end of the process of forming guide grooves or bits on an optical disc. A photocoupler 33 for detecting the identification signal as shown in FIG. 3(b) is used to detect the identification signal ζ formed on the optical disc. A photocoupler (33) is provided corresponding to the position of the identification signal 31 on the disk. In order to operate more stably against surface wobbling and reflectance changes of the optical disk, the light condensing system is constructed with a lens with a large depth of focus, but in such a system, the light spot at the focal position becomes large. The pitch at which the identification signal is formed is set to a larger value than the information signal. At the same time, the pitch at which the identification signal is formed is set to a larger value than the information signal. At the same time, a plurality of guide grooves or pits are formed in the radial direction of the disk. Therefore, by using the signal from the photocoupler 33 to identify the optical disc and changing the gain of the servo system or the power of the irradiated light according to the result, it is possible to correspond to an optical disc with any reflectance. Tonamu (Example 4) This reproducing method E-L This is a method in which the reflectance of the disc is first measured and the reproducing conditions are determined from the result of the reflectance measurement. Even if light from a semiconductor laser with a power of The point where the light intensity is maximum is approximately -
Due to the influence of pits and guide tracks on the disk surface, the force may have multiple peaks (among them, the position d that shows the highest peak value C corresponds to the focus position).The value of this peak is detected and the reflectance is The reflectance of the optical disc can be measured by converting it to
Alternatively, by switching the power of the irradiated light, it is possible to deal with optical discs with arbitrary reflectance.As a concrete operation, when the optical disc is set in the device and before entering the control operation, the servo section Even if the objective lens is brought closer, the voice coil is then driven so that the objective lens gradually moves away from the optical disk.By measuring the reflectance between them, the focus position can be determined. The method used to measure the reflectance of an optical disk using an optical system was to use a photocoupler for measuring reflectance. Even if the distance between the optical disk and the light source changes, there is little change in the amount of reflected light, making it possible to measure the reflectance more accurately (Example 5) In Examples 1 to 4, the optical system Here, the servo is within the operating range with respect to the difference in reflectance. In this method, a signal from a specific area of an optical disc, such as an area where management information of the disc is recorded, is played back, the error signal detected from the playback signal is evaluated, and the playback conditions are adjusted step by step to minimize the amount of error. For example, if you use an amplifier that can set multiple gains as shown in Figure 2, the preamplifier 11
1! - An error detection function is added to the demodulator 14 between the demodulator 14, and a reproduction error signal is generated when the error amount of the reproduction signal exceeds a predetermined value. If a playback error occurs during playback with a gain of In the case of the EFM modulation method used in CDs, etc., it can be evaluated by the amount of correction of the 01 flag of the error correction code (details are described in Ohmsha's Compact Disc Reader). This makes it possible to always play back optical discs with a high reflectance in an optimal state, improving the reliability of the information reproducing device. By combining the examples, more stable playback is possible.As described above, when reproducing signals from an optical disk, by optimally selecting the gain of the playback system or the power of the irradiated light, arbitrary reflections can be avoided. It is possible to play optical discs at

[Brief explanation of the drawing]

FIG. 1 shows the configuration of a method for setting light irradiation conditions in one embodiment of the present invention. FIG. 2 shows a partial configuration of the first embodiment of the present invention. FIG. Fig. 4 is a characteristic diagram of an embodiment of M4 of the present invention. 2... Optical disk drive 4... Semiconductor laser 8... Light detection sensor 9... Power setting a10... Laser drive starvation 12... Name of servo agent: Patent attorney Akira Okaji Two people: Figure Figure (α) Happy figure

Claims (8)

[Claims] (1) An optical information device for reproducing information signals recorded on an optical recording member, comprising: a light source; a light source driving means having a function of keeping the output of the light source constant; and recording light from the light source. an optical means having a function of guiding and condensing light onto a medium; a light detection means having a function of receiving reflected light from the recording medium and converting it into an electric signal; and a function of amplifying the electric signal, and having an amplification factor. amplification means having a function that can be set to a plurality of different values; a control means for driving the optical means according to the amplified signal to perform focus control or tracking control; and identification of the reflectance of the recording member. An optical information device comprising: an identification means, the amplification factor of the amplification means being changed according to the identification result of the identification means. (2) The identification means includes a function of determining whether the operating state of the control means is normal or not, and if it is determined that the operating state is not in a predetermined operation, generates an error signal indicating that control is impossible. 2. The optical information device according to claim 1, wherein the amplification factor of the amplification means is changed based on the error signal. (3) The identification means has a function of detecting an identification signal of the recording member formed in advance on the information recording member, and changes the amplification factor of the amplification means according to the detection result of the identification means. The optical information device according to claim 1. (4) An optical information device that reproduces information signals recorded on an optical recording member, comprising a light source and a function for keeping the output of the light source constant, and capable of setting the output to a plurality of different values. a light source driving means having a function of; an optical means including a function of guiding and condensing the light from the light source onto a recording medium; and a photodetector that receives reflected light from the recording medium and converts it into an electrical signal. means, an amplifying means having a function of amplifying the electrical signal, a control means for driving the optical means according to the amplified signal to perform focus control or tracking control, and identifying the reflectance of the recording member. 1. An optical information device, comprising: an identification means for identifying a light source, and changing an output of the light source driving means in accordance with an identification result of the identification means. (5) The identification means includes a function of determining whether the operating state of the control means is normal or not, and if it is determined that the operating state is not in a predetermined operation, generates an error signal indicating that control is impossible. 5. The optical information device according to claim 4, wherein the output power of the light source driving means is changed based on the error signal. (6) The identification means has a function of detecting an identification signal of the recording member formed in advance on the information recording member, and changes the set power level of the light source driving means according to the detection result of the identification means. The optical information device according to claim 4, characterized in that: (7) An optical information recording member that records information using a change in optical state, comprising an identification signal that can identify the reflectance of the recording member at a position close to the information area of the recording member. An optical information recording member characterized in that: (8) The optical information recording member according to claim 7, wherein the identification signal of the reflectance of the information recording member has a longer period than the information signal and is composed of a concavo-convex pit row.