WO2012137261A1 - 光ディスク装置 - Google Patents
光ディスク装置 Download PDFInfo
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- WO2012137261A1 WO2012137261A1 PCT/JP2011/002099 JP2011002099W WO2012137261A1 WO 2012137261 A1 WO2012137261 A1 WO 2012137261A1 JP 2011002099 W JP2011002099 W JP 2011002099W WO 2012137261 A1 WO2012137261 A1 WO 2012137261A1
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- WIPO (PCT)
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- laser light
- output
- photodetector
- optical disc
- light source
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
- G11B7/126—Circuits, methods or arrangements for laser control or stabilisation
- G11B7/1263—Power control during transducing, e.g. by monitoring
Definitions
- the present invention relates to an optical disc apparatus for optically reproducing data from an optical disc using a laser light source.
- the present invention also relates to an optical disc apparatus that optically records data on an optical disc using a laser light source and optically reproduces data from the optical disc.
- Data recorded on an optical disk is reproduced by irradiating a rotating optical disk with a relatively weak light beam having a constant intensity and detecting reflected light modulated by the optical disk.
- Information on pre-pits is recorded in a concentric or spiral shape in advance on the optical disk for reproduction only at the manufacturing stage of the optical disk.
- a recording material film capable of optically recording / reproducing data is deposited on a substrate on which concentric or spiral grooves are formed by a method such as vapor deposition.
- a recordable optical disc or a rewritable optical disc when recording data on a recording material film, the recording material film is irradiated with the light beam whose optical power is modulated as described above, so that the crystalline recording material film is non-coated.
- a crystalline recording mark is formed.
- the amorphous recording mark is formed by rapidly cooling after a part of the recording material film irradiated with the recording light beam rises to a temperature higher than the melting point. If the light power for irradiating the recording beam with the light beam is set to be low, the temperature of the recording mark irradiated with the light beam does not exceed the melting point and returns to crystalline after rapid cooling (erasing of the recording mark). In this way, the recording mark can be rewritten many times. If the emission power of the laser light source when recording data is inappropriate, the shape of the recording mark may be distorted and it may be difficult to accurately reproduce the data.
- the pit depth, track depth, and recording material film thickness are smaller than the optical disc thickness.
- the portion of the optical disc where data is recorded constitutes a two-dimensional surface and may be referred to as an “information recording layer” or “information surface”.
- an information recording layer or “information surface”.
- the optical disc has at least one such information recording layer.
- One information recording layer may actually include a plurality of layers such as a phase change material layer and a reflective layer.
- a high-density optical disc such as a Blu-ray disc (BD)
- at least one information recording layer is supported by a substrate, and the light incident side surface of the information recording layer is covered with a thin protective layer (light transmission layer).
- a thin protective layer light transmission layer
- another light transmission layer is interposed between the information recording layers.
- the depth from the light incident surface of such an optical disc (the “surface” of the optical disc) to the information recording layer of interest (the information recording layer where the focal point of the light beam is located) is typically 100 ⁇ m or less.
- focus control When reproducing data recorded on an optical disc or recording data on a recordable optical disc, the light beam must always be in a predetermined focused state on a target track in the target information recording layer.
- focus control the position of the objective lens is referred to as the normal direction of the information surface (hereinafter referred to as “the depth direction of the substrate”) so that the position of the focal point (focusing point) of the light beam is always on the information recording layer.
- the tracking control is to control the position of the objective lens in the radial direction of the optical disc (hereinafter referred to as “disc radial direction”) so that the spot of the light beam is located on a predetermined track.
- a focus shift or a track shift based on the light reflected from the optical disc and adjust the position of the light beam spot so as to reduce the shift. It is.
- the magnitudes of the focus shift and the track shift are indicated by a “focus error (FE) signal” and a “tracking error (TE) signal” generated based on the reflected light from the optical disc, respectively.
- the optical pickup includes a laser light source that emits a light beam, a photodetector that detects reflected light, and an optical system that irradiates the optical disc with laser light and guides the reflected light from the optical disc to the photodetector.
- the optical pickup of the conventional optical disk apparatus In order to perform stable recording and reproduction, it is necessary to control the light amount of the light beam applied to the optical disc to an appropriate level. For this reason, in the optical pickup of the conventional optical disk apparatus, a part of the light beam emitted from the laser light source is guided to a monitoring photodetector (light quantity detector), and the laser light source of the laser light source is based on the output of the light quantity detector. The output power is controlled.
- a monitoring photodetector light quantity detector
- the optical pickup of FIG. 6 includes a laser light source 2 that emits a light beam, a beam splitter 4 that reflects or transmits the light beam according to the polarization direction, and a beam splitter 4 out of the light beams emitted from the laser light source 2.
- a light amount detector 6 on which light transmitted through the light beam enters, a wave plate 5 that converts the light beam reflected by the beam splitter 4 into circularly polarized light, and a light beam that has passed through the wave plate 5 is placed on the information recording layer of the optical disc 100
- a focusing objective lens 8 and a signal light detector 10 that receives a light beam (reflected light) reflected by the information recording layer of the optical disc 100 and transmitted through the beam splitter 4 are provided.
- Such an optical pickup is disclosed in Patent Document 1, for example.
- the laser light source 2 includes a semiconductor laser that emits a polarized light beam.
- the polarization direction of the light beam when the light beam reflected by the information recording layer of the optical disc 100 is incident on the beam splitter 4 is the polarization of the laser beam when the light beam emitted from the laser light source 2 is incident on the beam splitter 4. It is rotated about 90 degrees from the direction. More specifically, the laser light transmitted through the wave plate 5 is circularly polarized light. However, when the laser light is reflected by the optical disc 100 and then passes through the wave plate 5, the circularly polarized light changes to linearly polarized light. The polarization direction of the linearly polarized light at this time coincides with the direction in which the beam splitter 4 can be transmitted. For this reason, the beam splitter 2 transmits and reflects the light beam as described above.
- a dotted line 501 shown in FIG. 6 indicates the optical axis of the laser beam.
- the optical pickup shown in FIG. 6 reproduces data from the optical disc 100 by irradiating the information recording layer of the optical disc 100 with a light beam and detecting the light reflected by the information recording layer of the optical disc 100 with the signal photodetector 10. .
- the light beam emitted from the laser light source 2 the light beam reflected by the beam splitter 4 and traveling toward the objective lens 8 passes through the objective lens 8 and is irradiated onto the information recording layer of the optical disc 100.
- the light reflected by the information recording layer of the optical disc 100 passes through the objective lens 8 and further passes through the beam splitter 4 and enters the signal light detector 10.
- a signal corresponding to the intensity or the amount of light incident on the signal light detector is generated by the photoelectric conversion of the signal light detector 10. This signal is used for reproducing data recorded on the information recording layer of the optical disc 100.
- the signal light detector 10 can also generate a tracking error signal and a focus error signal.
- the output from the light amount detector 6 is reflected by the beam splitter 4 and is approximately proportional to the light amount of the light beam that irradiates the information recording layer of the optical disc 100 via the objective lens 8.
- the output of the light amount detector 6 also increases or decreases. Therefore, if the laser light source 2 is controlled so that the output from the light amount detector 6 is constant, the light amount of the light beam that irradiates the optical disc 100 can be maintained constant.
- the light quantity detector 6 is usually provided in an optical pickup for performing recording as well as reproduction. This is because the power of the light beam for recording is larger than the power of the light beam for reproduction, and the adjustment needs to be performed with high accuracy. Therefore, in general, in an optical disc apparatus capable of both recording and reproduction, power control is performed using the output of the light quantity detector 6 shown in FIG.
- FIG. 7 shows an example of a conventional optical pickup that does not include a monitoring photodetector such as the light quantity detector 6 described above.
- a light quantity detection element for measuring the emission power of the light beam is provided inside the laser light source 12 (for example, Patent Document 2).
- a configuration (eg, Patent Document 2) of a laser light source including such a light amount detection element will be described with reference to FIG.
- FIG. 8 schematically shows the internal configuration of the laser light source 12.
- the laser light source 12 shown in FIG. 8 includes a semiconductor laser element 124 and a monitoring light amount detection element 128 in the same package.
- Laser light 122 used as a light beam is emitted from one of the resonator end faces (exit end face) of the semiconductor laser element 124.
- a weak laser beam 126 used for monitoring is emitted from the other end face (rear end face) of the resonator end face of the semiconductor laser element 124. Since an antireflection film is deposited on the rear end face of the resonator end face in the semiconductor laser element 124, the intensity of the laser beam that passes through the rear end face is low.
- the semiconductor laser element 124 has a p-side electrode and an n-side electrode (not shown).
- a voltage is applied between both electrodes of the semiconductor laser element 124 via a wiring (not shown), and a driving current flows through the semiconductor laser element 124, the inside of the semiconductor laser element 124 corresponds to the magnitude of the driving current. Luminescence occurs. As a result, laser beams 122 and 126 are emitted from the cavity end face.
- a light amount detection element 128 that detects weak laser light 126 for monitoring is mounted at a position facing the rear end face of the resonator of the semiconductor laser element 124.
- the amount of laser light 122 emitted from the exit end face of the resonator is proportional to the amount of weak laser light 126 emitted from the rear end face. Therefore, the light quantity of the laser beam 122 emitted from the emission end face of the semiconductor laser element 124 can be obtained by the light quantity detection element 128.
- the output power of the laser light source 12 is controlled using the output of the light quantity detection element 128 (FIG. 8) provided in the laser light source 12.
- the light quantity detection element 128 is in the same package as the semiconductor laser element 124 as shown in FIG. Changes. Since the output characteristics of the light quantity detection element 128 depend on temperature, there is a problem that the light quantity control based on the output of the light quantity detection element 128 becomes unstable.
- the semiconductor laser element 124 If the semiconductor laser element 124 is used for a long time, the emission end face of the resonator of the semiconductor laser element 124 deteriorates. As a result, the ratio between the light amount of the laser light 122 and the light amount of the monitor light 128 changes over time, and there is a problem that stable output control cannot be performed.
- An optical disc apparatus includes a laser light source that emits laser light, a photodetector that detects a signal from the optical disc, and irradiates the optical disc with the laser light, and reflects reflected light from the optical disc to the photodetector.
- a guiding optical system, a value output from the photodetector when the laser light source emits the laser light, and reflected light from the optical disk does not reach the photodetector, and emission of the laser light source A memory for storing information defining a relationship with power; and an output of the photodetector when the laser light source emits the laser beam and reflected light from the optical disc does not reach the photodetector.
- a control unit for controlling the emission power of the laser light source based on the information stored in the memory.
- the memory stores a value output from the photodetector when the laser light source emits the laser light and the laser light is not focused on the information recording layer of the optical disc. To do.
- the memory stores a value output from the photodetector when the laser light source emits the laser light and the optical disk is not loaded.
- the disc device of the present invention includes a laser light source that emits laser light, a light amount detection element that detects the power of the laser light, a photodetector that detects a signal from the optical disc, and the optical disc that is irradiated with the laser light.
- An optical system that guides reflected light from the optical disk to the photodetector, and the laser when the laser light source emits the laser light and the reflected light from the optical disk does not reach the photodetector.
- Memory for storing information defining the relationship between the output power of the light source and the value output from the photodetector, and information defining the relationship between the output of the light quantity detection element and the output of the photodetector,
- a control unit that controls the emission power of the laser light source based on the output of the light quantity detection element and information stored in the memory;
- control unit outputs from the photodetector at a certain timing when the laser light source emits the laser light and reflected light from the optical disc does not reach the photodetector.
- the measured value is measured, and information defining the relationship between the output of the light quantity detection element and the output of the photodetector is calibrated.
- a value output from the light amount detection element when the laser light source emits the laser light with a first emission power and reflected light from the optical disc does not reach the photodetector.
- the output of the photodetector is c based on the information stored in the memory, whereas the actual output value from the photodetector is b, If the difference between b and c is smaller than a predetermined value, the emission power of the laser light source is controlled so that the output a ′ of the light quantity detection element corresponding to the output c of the photodetector is obtained.
- the emission power of the laser light source is controlled so that the output of the light quantity detection element is a.
- the laser light source includes a semiconductor laser element that generates the laser light and a container that covers the semiconductor laser element, and the light amount detection element is provided inside the container. Yes.
- the present invention it is possible to stabilize the light amount of the light beam applied to the optical disc to a constant light amount without adding a light amount detector in the optical pickup.
- (A) is a figure which shows the relationship between the output power of the laser light source 2, and the output of the photodetector 10
- (b) is a figure which shows the relationship between the output power and the output of the light quantity detection element 128, (c).
- the figure which shows the relationship between the output of the photodetector 10 and the output of the light quantity detection element 128 The figure for demonstrating the emission power control of the optical disk apparatus of the 2nd Embodiment of this invention.
- the figure for demonstrating the emission power control of the optical disk apparatus of the 2nd Embodiment of this invention The figure which shows the structure of the conventional optical pickup
- the figure which shows the structure of the conventional optical pickup The figure which shows the detail of the laser light source used for this invention or the conventional optical pick-up Flowchart for explaining emission power control of the optical disc apparatus according to the second embodiment of the present invention. Flowchart for explaining emission power control of the optical disc apparatus according to the second embodiment of the present invention.
- the optical pickup 30 includes a laser light source 2 that emits laser light, a light detector 10 for detecting a signal from the optical disk 100, and irradiates the optical disk 100 with the laser light, and reflects light reflected from the optical disk 100 as a light detector. 10 and an optical system 200 that leads to 10.
- the optical system 200 reflects or transmits a light beam according to the polarization direction, converts the light beam reflected by the beam splitter 4 into circularly polarized light, reflects from the optical disc 100, and passes through the objective lens 8.
- the optical pickup 30 further includes components (not shown) such as an actuator for driving the objective lens 8.
- the memory 300 in the optical disc apparatus of the present embodiment has a value output from the photodetector 10 when the laser light source 2 emits laser light and the reflected light from the optical disc 100 does not reach the photodetector 10.
- Information defining the relationship with the emission power of the laser light source 2 is stored.
- the “relation” is proportional as will be described later. Therefore, this “information defining the relationship” is, for example, a numerical value of both ⁇ and ⁇ when the output power is ⁇ when the output power has a certain value ⁇ . There may be a value of ⁇ / ⁇ which is a ratio of these numerical values. If ⁇ is a known value or a fixed value, ⁇ may be “information defining the relationship”.
- the control unit 400 outputs the information stored in the memory 300 and the light detector 10 when the laser light source 2 emits laser light and the reflected light from the optical disc 100 does not reach the light detector 10.
- the emission power of the laser light source 2 is controlled based on the value.
- the optical pickup 30 among the light beams emitted from the laser light source 2, the light beam reflected by the beam splitter 4 is condensed on the information recording layer of the optical disc 100 by the objective lens 8.
- the light beam reflected by the information recording layer of the optical disc 100 passes through the objective lens 8 and the beam splitter 4 and enters the photodetector 10.
- the photodetector 10 converts incident light into an electrical signal by photoelectric conversion, and outputs a value corresponding to the amount of incident light.
- the laser light source 2 when the laser light source 2 emits a light beam, originally unnecessary reflection occurs in any part in the optical pickup 30, for example, any part of the optical system 200, and stray light is generated.
- the reflectance at the surface of the objective lens 8 is not zero.
- a part of the light beam transmitted through the objective lens 8 can be reflected by, for example, a casing or other parts of the optical disc apparatus. For this reason, a part of the light reflected by the objective lens 8 and the casing and parts of the optical disk apparatus is then transmitted through the beam splitter 4 and incident on the photodetector 10.
- part of the light beam emitted from the laser light source 2 becomes stray light and enters the photodetector 10.
- the output of the photodetector 10 due to such stray light is detected if the optical beam is not focused on the information recording layer of the optical disc 100 even when the optical disc 100 is loaded in the optical disc apparatus.
- Such stray light enters the photodetector 10 and is photoelectrically converted, and has an output value that is not zero. For this reason, even when the optical disc 100 is not loaded or when the information recording layer of the optical disc 100 is not focused, as long as the laser beam 2 emits a light beam, the output of the photodetector 10 is zero. Absent. The inventor has found that the output of the photodetector 10 caused by stray light is substantially proportional to the output power of the laser light source 2, and completed the present invention. That is, in the present invention, stray light is actively used, and the emission power of the laser light source is controlled based on the output of the photodetector 10 for generating a signal.
- the value ⁇ output from the photodetector 10 is stored in advance when the output power is set to the predetermined value ⁇ in a state where the optical disk is not reproduced or recorded. This value ⁇ is due to stray light when the output power value is ⁇ .
- the relationship between the output power and the photodetector output caused by the stray light is proportional.
- a straight line defining a proportional relationship is determined from the output power value ⁇ and the output value ⁇ of the photodetector 10 due to stray light.
- the memory 300 stores information that defines this proportional relationship, for example, information such as the slope of a straight line. This information may be a table indicating the correspondence between the output power and the photodetector output. Note that the memory 300 need not be provided inside the optical pickup 30.
- focusing control on the information recording layer of the optical disc 100 is interrupted, preferably at regular intervals, in the operation mode in which the optical disc 100 is reproduced or recorded.
- the light beam remains emitted from the laser light source 2 even when the reproduction / recording mode is interrupted.
- reflection on the optical disc 100 does not occur, and stray light enters the photodetector 10. Therefore, the output power to the laser light source 2 can be adjusted based on the output of the photodetector 10 obtained when the reproduction / recording mode is interrupted. This is explained as follows using the example of FIG.
- the above value ⁇ is the target value of the emission power of the laser light source.
- the value of the output of the photodetector 10 obtained when the reproduction / recording mode is interrupted should be ⁇ .
- the output value of the photodetector 10 is smaller than ⁇ , it means that the output power value of the laser light source 2 is smaller than ⁇ . For this reason, what is necessary is just to change an output power until the value of the output of the photodetector 10 corresponds to (beta).
- the output power of the laser light source 2 is increased little by little, and the output of the light detector 10 is measured each time the output power is increased, and when the output of the light detector 10 slightly exceeds ⁇ , The increase in emission power may be stopped. Further, the amount of change in the emission power of the laser light source 2 may be determined by calculation using the difference between the output value of the photodetector 10 and ⁇ and the value of the proportional coefficient. Note that the emission power of the laser light source 2 can be controlled by adjusting the drive current of the semiconductor laser included in the laser light source 2. Generally, when the drive current is increased, the output power is increased, and when the drive current is decreased, the output power is decreased.
- the optical disc apparatus of the present embodiment includes an optical pickup 30, a spindle motor 43 that rotates the optical disc 100, a transfer motor 42 that controls the position of the optical pickup 30, and a control unit that controls these operations.
- the optical pickup 30 is connected to a pre-processing circuit 36 that performs signal processing and a drive circuit 41 that controls the operation of the optical pickup 30, and exchanges electrical signals between them.
- the data optically read from the optical disc 100 is converted into an electrical signal by the photodetector 10 (FIG. 1) of the optical pickup 30.
- This electrical signal is input to the preprocessing circuit 36 via a signal connection means (not shown).
- the pre-processing circuit 36 generates a servo signal including a focus error signal and a tracking error signal based on the electrical signal obtained from the optical pickup 30, and also provides an analog signal such as a waveform equivalent of a reproduction signal, a binary slice, and synchronization data. Process.
- the servo signal generated by the preprocessing circuit 36 is input to the control circuit 37.
- the control circuit 37 causes the optical spot of the optical pickup 30 to follow the optical disc 100 via the drive circuit 41.
- the drive circuit 41 is connected to the optical pickup 30, the transfer motor 42, and the spindle motor 43.
- the drive circuit 41 realizes a series of controls such as focus control and tracking control of the objective lens 8, transfer control, and spindle motor control with a digital servo.
- driving of a transfer motor 42 for transferring the optical pickup 30 to the inner periphery and outer periphery of the optical disc 100, and a spindle motor for rotating the optical disc 100 43 is appropriately driven.
- the synchronization data generated by the preprocessing circuit 36 is subjected to digital signal processing by the system controller 40, and the recording / reproduction data is transferred to the host via an interface circuit (not shown).
- the pre-processing unit 36, the control circuit 37, and the system controller 40 are connected to the central processing unit 38 and operate according to instructions from the central processing unit 38.
- a program that prescribes a series of operations including a control operation of rotating the optical disc 100, transporting the optical pickup 30 to a target position, forming a light spot on a target track of the optical disc 100, and following the program as firmware. It is stored in a semiconductor device such as a nonvolatile memory 39.
- firmware is read from the non-volatile memory 39 by the central processing unit 38 in accordance with a required operation form.
- preprocessing circuit 36 the control circuit 37, the central processing unit 38, the nonvolatile memory 39, and the system controller 40 function as the control unit 400 as a whole.
- the emission power of the laser beam can be controlled with high accuracy even when a small and inexpensive optical pickup for player use that is exclusively for reproduction is used. Is possible. Therefore, it is possible to use an optical pickup for a player for data recording that requires the emission power to be controlled with high accuracy. Since the player's optical pickup does not require high output power for data recording, a semiconductor laser element having low output power is generally used. However, it is possible to record data on the optical disk even when the output power is relatively low. For example, according to a technique disclosed in an application such as PCT / JP2010 / 007, since a recording mark is long, data can be recorded even with a relatively low emission power.
- the optical disc apparatus of the present embodiment basically has the same configuration as that of the optical disc apparatus of the first embodiment (FIGS. 1 and 3). The difference is in the method of controlling the emission power of the laser light source 2. Therefore, the point that the configuration and operation of the optical disk device of the present embodiment are the same as the configuration and operation of the optical disk device of Embodiment 1 will not be described repeatedly here.
- the emission power of the laser light source 2 is set to a predetermined value ⁇ in a state where the optical disc 100 is not reproduced or recorded in advance, and the value ⁇ output from the photodetector 10 at that time is stored in the memory. 300.
- the relationship between the output power and the photodetector output which is indicated by the solid line in FIG.
- the output from the photodetector 10 can be obtained in a state where the reflected light from the optical disc 100 is not incident on the photodetector 10 because stray light generated by reflection in the optical pickup 30 is detected by the photodetector. This is because the light enters the beam 10. This stray light is substantially proportional to the emission power of the laser light source 2.
- the laser light source 2 of the conventional optical pickup includes a light amount detection element 128 provided inside a package (container) that covers the semiconductor laser element 124.
- a light amount detection element 128 is not necessary, but in this embodiment, the light amount detection element 128 provided in the normal laser light source 2 is used.
- the output value ⁇ from the light amount detection element 128 mounted on the laser light source 2 is also stored. In this way, the relationship between the output power of the laser light source 2 and the output of the light quantity detector 128 is obtained as shown by the solid line in FIG.
- the laser light source 2 when reproducing or recording an optical disk, the laser light source 2 is controlled so that the output of the light amount detection element 128 of the laser light source 2 becomes a desired value.
- the output of the light quantity detection element 128 can be measured at any timing without interrupting the reproduction / recording operation mode of the optical disk. That is, even if the reflected light from the optical disc 100 is incident on the photodetector 10, the output of the light quantity detection element 128 can be obtained. Therefore, since the amount of light for controlling the emission power is detected, there is no need to interrupt the reproduction / recording operation and detect stray light.
- the relationship between the output of the light detector 10 and the output of the light quantity detection element 128 should follow the relational expression shown in FIG. 4C obtained in advance.
- the output of the light amount detection element 128 varies with the temperature change of the laser light source 2
- the actual relationship may have changed from the relationship shown in FIG. 4C obtained in advance. Therefore, it is preferable to detect this fluctuation regularly or irregularly.
- the focusing control to the information recording layer of the optical disc is interrupted at a certain timing, and the reflected light from the information recording layer It does not enter the detector 10.
- the “certain timing” may be a certain interval (for example, every 10 seconds to 1 minute), or before or after the optical disk apparatus performs a specific operation. In this way, a state in which stray light enters the photodetector 10 is formed, and then the output of the photodetector 10 and the output of the light amount detection element 128 are measured.
- the relationship between the values b and c is c ⁇ b ⁇ k ⁇ c (k is a positive constant) If so, the output of the light quantity detection element 128 is controlled to be a ′, c ⁇ b> k ⁇ c (k is a positive constant) In such a case, the output of the light quantity detection element 128 may be controlled to be a.
- the output of the light quantity detection element 128 of the laser light source 2 is the value a and the output of the photodetector 10 is the value b.
- the measured value obtained at this time is indicated by point D in the figure. This deviates from the relational expression indicated by the solid line passing through the point E in the figure, which is the relational expression obtained in FIG.
- a relational expression of a one-dot chain line passing through the point D is derived, and the output from the light amount detection element 128 corresponding to the value c output from the signal light detector obtained from FIG.
- the input current to the laser light source is controlled so as to be point F).
- the relationship between the values b and c is bc ⁇ k ⁇ c (k is a positive constant) Is controlled so that the output of the light quantity detection element 128 becomes a ′, bc> k ⁇ c (k is a positive constant)
- the output of the light quantity detection element 128 may be controlled to be a.
- an antireflection film is usually provided on optical components such as lenses and mirrors that constitute the optical system of the optical pickup. It is effective to increase the stray light incident on the signal light detector by omitting this antireflection film. Due to the absence of the antireflection film, the stray light incident on the photodetector increases, and the control accuracy by the output of the photodetector 10 increases. Furthermore, you may mirror-finish the surface of the housing
- the laser light source 12 as shown in FIG. 8 is used, but the configuration of the laser light source is not limited to such an example.
- the light amount detection element 128 in the laser light source may be configured to detect a part of the light emitted from the emission end face of the semiconductor laser element 124.
- the optical disk device of the present invention is suitable not only for optical pickup for recording as well as for reproduction, but also for use in recording data on an optical disk using an inexpensive optical pickup having a structure exclusively for reproduction. Used.
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Abstract
Description
以下、本発明による光ディスク装置の第1の実施形態を説明する。
次に、本発明の光ディスクの第2の実施形態を説明する。
c-b≦k×c (kは正の定数)
となる場合は、光量検出素子128の出力がa'となるように制御し、
c-b>k×c(kは正の定数)
となる場合は、光量検出素子128の出力がaとなるように制御しても良い。
b-c ≦ k×c (kは正の定数)
となる場合は光量検出素子128の出力がa’となるように制御し、
b-c > k×c (kは正の定数)
となる場合は、光量検出素子128の出力がaとなるように制御しても良い。
4 ビームスプリッタ
8 対物レンズ
10 光検出器
30 光ピックアップ
36 前処理回路
37 制御回路
38 中央演算処理部
39 不揮発性メモリ
40 システムコントローラ
41 駆動回路
42 移送モータ
43 スピンドルモータ
100 光ディスク
101 光軸
122 レーザ光
124 半導体レーザ素子
126 レーザ光
128 光量検出素子
200 光学系
300 メモリ
400 制御部
Claims (8)
- レーザ光を出射するレーザ光源と、
光ディスクからの信号を検出する光検出器と、
前記レーザ光を前記光ディスクに照射し、前記光ディスクからの反射光を前記光検出器へ導く光学系と、
前記レーザ光源が前記レーザ光を出射し、かつ、前記光ディスクからの反射光が前記光検出器に届いていない時における前記光検出器から出力される値と前記レーザ光源の出射パワーとの関係を規定する情報を格納するメモリと、
前記レーザ光源が前記レーザ光を出射し、かつ、前記光ディスクからの反射光が前記光検出器に届いていない時における前記光検出器の出力と前記メモリで格納された情報とに基づいて前記レーザ光源の出射パワーを制御する制御部と、
を備える光ディスク装置。 - 前記メモリは、前記レーザ光源が前記レーザ光を出射し、かつ、前記レーザ光が前記光ディスクの情報記録層にフォーカスしていない時に、前記光検出器から出力される値を格納する、請求項1に記載の光ディスク装置。
- 前記メモリは、前記レーザ光源が前記レーザ光を出射し、かつ、前記光ディスクが装填されていない時に、前記光検出器から出力される値を格納する、請求項1に記載の光ディスク装置。
- レーザ光を出射するレーザ光源と、
前記レーザ光のパワーを検出する光量検出素子と、
光ディスクからの信号を検出する光検出器と、
前記レーザ光を前記光ディスクに照射し、前記光ディスクからの反射光を前記光検出器へ導く光学系と、
前記レーザ光源が前記レーザ光を出射し、かつ、前記光ディスクからの反射光が前記光検出器に届いていない時における前記レーザ光源の出射パワーと前記光検出器から出力される値との関係を規定する情報と、前記光量検出素子の出力と前記光検出器の出力との関係と規定する情報とを格納するメモリと、
前記光量検出素子の出力と前記メモリに格納された情報とに基づいて前記レーザ光源の出射パワーを制御する制御部と、
を備えるディスク装置。 - 前記制御部は、あるタイミンクで、前記レーザ光源が前記レーザ光を出射し、かつ、前記光ディスクからの反射光が前記光検出器に届いていない時における前記光検出器から出力される値を測定し、前記光量検出素子の出力と前記光検出器の出力との関係と規定する情報を校正する、請求項4に記載の光ディスク装置。
- 前記レーザ光源が第1の出射パワーで前記レーザ光を出射し、かつ、前記光ディスクからの反射光が前記光検出器に届いていない時における前記光量検出素子から出力される値がaである場合において、前記メモリに格納された前記情報に基づけば前記光検出器の出力がcであるのに対して、前記光検出器から実際に出力される値がbであるとき、bとcとの差異が所定値よりも小さければ、前記光検出器の出力cに相当する光量検出素子の出力a'となるように前記レーザ光源の出射パワーを制御する、請求項4に記載の光ディスク装置。
- bとcとの差異が前記所定値よりも大きければ、前記光量検出素子の出力がaとなるように前記レーザ光源の出射パワーを制御する、請求項6に記載の光ディスク装置。
- 前記レーザ光源は、前記レーザ光を生成する半導体レーザ素子と、前記半導体レーザ素子をカバーする容器とを有しており、
前記光量検出素子は、前記容器の内部に設けられている請求項4から7のいずれかに記載の光ディスク装置。
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JP2011536222A JPWO2012137261A1 (ja) | 2011-04-08 | 2011-04-08 | 光ディスク装置 |
PCT/JP2011/002099 WO2012137261A1 (ja) | 2011-04-08 | 2011-04-08 | 光ディスク装置 |
US13/377,946 US20120257487A1 (en) | 2011-04-08 | 2011-04-08 | Optical disc drive |
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PCT/JP2011/002099 WO2012137261A1 (ja) | 2011-04-08 | 2011-04-08 | 光ディスク装置 |
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Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH05128573A (ja) * | 1991-11-08 | 1993-05-25 | Pioneer Electron Corp | レーザダイオード駆動制御装置 |
JP2000339737A (ja) * | 1999-05-25 | 2000-12-08 | Sony Corp | 記録装置、オフセット除去方法 |
JP2006107574A (ja) * | 2004-10-01 | 2006-04-20 | Sony Corp | 光ディスク駆動装置および方法、記録媒体、並びにプログラム |
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DE4415508A1 (de) * | 1994-05-03 | 1995-11-09 | Thomson Brandt Gmbh | Abtastgerät mit Adaptation |
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- 2011-04-08 WO PCT/JP2011/002099 patent/WO2012137261A1/ja active Application Filing
- 2011-04-08 JP JP2011536222A patent/JPWO2012137261A1/ja active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH05128573A (ja) * | 1991-11-08 | 1993-05-25 | Pioneer Electron Corp | レーザダイオード駆動制御装置 |
JP2000339737A (ja) * | 1999-05-25 | 2000-12-08 | Sony Corp | 記録装置、オフセット除去方法 |
JP2006107574A (ja) * | 2004-10-01 | 2006-04-20 | Sony Corp | 光ディスク駆動装置および方法、記録媒体、並びにプログラム |
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