JP4340689B2 - Optical pickup and information recording / reproducing apparatus - Google Patents

Description

【Technical field】
[0001]
  The present invention relates to an optical pickup device used for recording and reproducing information on an information recording medium such as an optical disk.
[Background]
[0002]
  Conventionally, an information recording / reproducing apparatus (hereinafter simply referred to as “information recording / reproducing”) such as a compatible player for recording and reproducing data on various optical discs having different standards such as DVD (Digital Versatile Disc) and CD (Compact Disc). Various devices are provided. In this type of information recording / reproducing apparatus, it is desired to improve the recording speed of data on an optical disc such as a DVD-R from the viewpoint of improving user convenience and differentiating from other products.
[0003]
  However, in an optical disc such as a DVD-R or DVD-RW, when the total energy amount of the light beam irradiated per predetermined unit time exceeds a predetermined threshold, or the temperature on the optical disc exceeds a certain value. In this case, a color change or a phase change occurs, and various data are recorded thereby. Therefore, when the relative speed of the optical disc with respect to the light beam is increased by increasing the recording speed, the amount of energy of the irradiated light beam is reduced. Unless it is increased, data recording cannot be realized.
[0004]
  On the other hand, the light source used in this type of information recording / reproducing apparatus increases the amount of heat radiation as the outputable wattage increases. Currently, a light source of about 150 mW (milliwatt) is realized from the viewpoint of heat radiation countermeasures. Only. For this reason, the theoretical maximum recording speed depends on the performance of the light source, and unless a new light source is developed, no further improvement in the recording speed can be expected.
[0005]
  Therefore, conventionally, for example, when recording data on a CD-R, two light sources corresponding to each light beam having a wavelength of 780 nm and 650 nm are simultaneously turned on, and tracking servo and focus servo are performed using the light beam having a wavelength of 780 nm. Thus, a proposal has been made to increase the utilization efficiency of a 650 nm light beam used for data recording (see Patent Document 1).
[Patent Document 1]
JP 2000-173084 A
DISCLOSURE OF THE INVENTION
[Problems to be solved by the invention]
[0006]
  Incidentally, in one apparatus described in Patent Document 1, a configuration is adopted in which two light beams having different wavelengths reflected by an optical disc are received by the same photodetector. However, when such a configuration is employed, it is difficult to separate each light beam from the received light beam unless the optical axis is accurately aligned, and crosstalk occurs between the two beams. When crosstalk occurs in this way, one light beam becomes noise with respect to the other light beam, making it difficult to control data recording or tracking.
[0007]
  The present application has been made in view of the circumstances described above. As an example of the problem, the recording speed of an optical disc such as a DVD-R is improved while adopting a simple configuration, and data recording is performed reliably. An object of the present invention is to provide an optical pickup and an information recording / reproducing apparatus capable of reproducing.
[Means for Solving the Problems]
[0008]
  In order to solve the above-described problem, in one aspect of the present application, the optical pickup according to claim 1 condenses the light beam output from the light source on the information recording medium, and receives the reflected light from the information recording medium. A first light source that outputs a first light beam having a first wavelength, and a second light source that outputs a second light beam having a second wavelength different from the first wavelength; A light receiving unit that receives the reflected light reflected by the information recording medium and outputs a signal corresponding to the amount of received light; and is installed on the optical path of the reflected light from the information recording medium to the light receiving unit and is incident thereon. A filter that controls transmission of the second light beam, and a light source control unit that controls both the first light source and the second light source and outputs either one or both of the first light beam and the second light beam. When, When both the first and second light beams are output, filter control means for controlling the filter to limit transmission of the second beam, detection means for discriminating the type of the information recording medium, The light source control means determines the presence or absence of the output of the light beam from the first light source and the second light source according to the detection result of the detection means, and the information recording medium detected by the detection means Is a dye type information recording medium, the light source control means outputs the light beam only from a light source capable of outputting a laser beam having a wavelength suitable for the information recording medium.
[0009]
  In another aspect of the present application, the information recording / reproducing apparatus according to claim 9 condenses the light beam output from the light source on the information recording medium and receives the reflected light from the information recording medium. An information recording / reproducing apparatus including a pickup, wherein the optical pickup includes a first light source that outputs a first light beam having a first wavelength, and a second wavelength that is different from the first wavelength. A second light source that outputs two light beams; a light receiving unit that receives the reflected light reflected by the information recording medium and outputs a signal corresponding to the amount of received light; and the reflection from the information recording medium to the light receiving unit One of the first and second light beams is installed on the optical path of the light to control the transmission of the incident second light beam, and controls both the first light source and the second light source. Or both Light source control means for outputting, filter control means for controlling transmission of the second beam when both the first and second light beams are output, and types of the information recording medium Detecting means for determining the output of the light beam from the first light source and the second light source according to a detection result of the detecting means, and the detecting means When the information recording medium detected by the above is a dye-type information recording medium, the light source control means outputs the light beam only from a light source capable of outputting a laser beam having a wavelength suitable for the information recording medium. And
[Brief description of the drawings]
[0010]
  FIG. 1 is a block diagram showing a configuration of an information recording / reproducing apparatus RP in an embodiment.
  FIG. 2 is a conceptual diagram showing a focused spot on the optical disc DK and an energy distribution on the focused spot in the same embodiment.
  FIG. 3 is a diagram showing a configuration example when the wavelength filter 18 in the embodiment is configured using an inorganic EC material.
  FIG. 4 is a diagram showing a configuration example when the wavelength filter 18 in the embodiment is configured using an organic EC material.
[Explanation of symbols]
[0011]
  RP ... Information recording / reproducing device
  SP: Signal processor
  C ... Control unit
  D ... Drive circuit
  PU: Optical pickup
  S ... Servo circuit
  P ... Playback unit
BEST MODE FOR CARRYING OUT THE INVENTION
[0012]
  [1]Embodiment
  The configuration and operation of the information recording / reproducing apparatus RP according to the present embodiment will be described below with reference to FIG. 1 showing the schematic configuration of the information recording / reproducing apparatus RP according to the present embodiment. The information recording / reproducing apparatus RP according to the present embodiment is an application of the information recording / reproducing apparatus of the present application to a compatible player that records and reproduces data with respect to an optical disc DK compatible with both CD and DVD standards.
[0013]
  As shown in the figure, the information recording / reproducing apparatus RP according to the present embodiment is roughly divided into a signal processing unit SP, a control unit C, a driving circuit D, an optical pickup PU, a servo circuit S, and a reproducing unit P. ,have.
[0014]
  The signal processing unit SP has an input terminal. The signal processing unit SP performs signal processing on data input through the terminal and outputs the processed data to the control unit C. Specific processing contents performed in the signal processing unit SP are arbitrary. For example, after the input data is compressed by a compression method such as MPEG (Moving Picture Experts Group), the data is output to the control unit C. You may make it do.
[0015]
  The control unit C is mainly configured by a CPU (Central Processing Unit), and controls each unit of the information recording / reproducing apparatus RP. For example, when data is recorded on the optical disc DK, the control unit C outputs a drive signal corresponding to the data input from the signal processing unit SP to the drive circuit D. In addition, when reproducing data recorded on the optical disc DK, the control unit C outputs a predetermined drive signal to the drive circuit D regardless of the presence or absence of data input from the signal processing unit SP.
[0016]
  The drive circuit D is mainly configured as an amplifier circuit, amplifies the drive signal input from the control unit C, and then supplies the amplified signal to the optical pickup PU. The amplification factor in the drive circuit D is controlled by the control unit C, and when data is recorded on the optical disk DK, the amount of energy that can cause a phase change or dye discoloration from the optical pickup PU to the optical disk DK (hereinafter, “ The amplification factor is controlled so that a light beam of “recording power” is output. On the other hand, when data recorded on the optical disc DK is reproduced, a light beam having an energy amount (hereinafter referred to as “reproduction power”) that does not cause a change such as dye discoloration in the optical disc DK is output from the optical pickup PU. The amplification factor is controlled.
[0017]
  The optical pickup PU includes, for example, a first light source 11, a second light source 12, a first beam splitter 13, a second beam splitter 14, an actuator unit 15, a condenser lens 16, a photodetector 17, and a wavelength filter. 18 and irradiating the optical disk DK with a light beam to record and read data on the optical disk DK.
[0018]
  Both the first light source 11 and the second light source 12 are configured by laser diodes, and output light beams having different wavelengths based on the drive signal supplied from the drive circuit D. In the present embodiment, the first light source 11 and the second light source 12 are light beams in which the first light source 11 has a wavelength of 660 nm in order to realize data recording and reproduction corresponding to both DVD and CD standards. The second light source 12 outputs a light beam having a wavelength of 780 nm.
[0019]
  The light beams output from the first light source 11 and the second light source 12 are applied to the first and second beam splitters 13 and 14 disposed on the optical path of each light beam. The first beam splitter 13 and the second beam splitter 14 are constituted by, for example, dichroic mirrors, and reflect the light beams emitted from the corresponding light sources 11 and 12. When the first and second beam splitters 13 and 14 are constituted by dichroic mirrors, the first beam splitter 13 reflects 90% of the light beam of 660 nm, transmits 10%, and transmits the light beam of 780 nm 100%. It is desirable to adopt a dichroic mirror for the second beam splitter 14 that reflects 90% of the 780 nm light beam and transmits 10% and transmits the 660 nm light beam 100%.
[0020]
  In this way, the light beams reflected by the first beam splitter 13 and the second beam splitter 14 pass through a wave plate (not shown) provided in the actuator unit 15 and are installed in the actuator unit 15. The light enters the objective lens and is condensed on the optical disk DK. In order to realize such a light beam condensing function, the actuator unit 15 is provided with a mechanism for moving the objective lens. Note that the specific configuration of the actuator unit 15 is arbitrary.
[0021]
  Next, the light beam applied to the optical disc DK is reflected by the optical disc DK, and then enters the first beam splitter 13 and the second beam splitter 14 through the objective lens of the actuator unit 15 again. The light passes through the beam splitter 13 and the second beam splitter 14 and enters the condenser lens 16. Then, the reflected light incident on the condenser lens 16 is condensed on the photodetector 17 by the condenser lens 16.
[0022]
  The photodetector 17 is constituted by, for example, a photodiode, receives the light beam emitted from the condenser lens 16, and outputs a signal corresponding to the amount of received light of the reflected light. Specifically, an RF signal corresponding to the amount of reflected light is output to the control unit C, and signals necessary for tracking servo and focus servo are output to the servo circuit S.
[0023]
  In this way, when the RF signal is supplied from the photodetector 17, the control unit C supplies (a) the RF signal to the playback unit P during playback, and data corresponding to the RF signal is output to the output terminal. (B) at the time of recording, for example, an address on the optical disk DK is acquired based on the RF signal, or data to be recorded is recorded. The output timing of the drive signal corresponding to is determined.
[0024]
  The servo circuit S is configured by an arithmetic circuit, calculates a servo amount related to tracking and focusing based on a signal supplied from the photodetector 17, and outputs a control signal corresponding to the calculation result to the actuator unit 15. As a result, in the actuator unit 15, the position of the objective lens is changed based on the control signal fed back from the servo circuit S, and tracking servo and focus servo are performed.
[0025]
  A specific method for realizing the tracking servo and the focus servo is arbitrary. However, in the present embodiment, the following method is adopted to make the description specific. That is, the photodetector 17 is divided into four parts, and a cylindrical lens is adopted as the condenser lens 16. For the focus servo, the servo amount is calculated in the servo circuit S using the astigmatism method, and for the tracking servo, the servo amount is calculated in the servo circuit S based on the received light amount in each region.
[0026]
  Here, in the information recording / reproducing apparatus RP according to the present embodiment having such a configuration, when trying to improve the recording speed of data on the optical disc DK, the total amount of energy of the light beam applied to the optical disc DK per unit time is as follows. Since it is necessary to exceed a predetermined threshold value or the temperature on the optical disc DK is equal to or higher than a certain value, it is necessary to increase the total amount of energy of the light beam applied to the optical disc DK. On the other hand, when reproducing data recorded on the optical disc DK, there is no need to increase the amount of energy of the light beam applied to the optical disc DK. Therefore, in the present embodiment, the control unit C performs the following control when recording and reproducing data on the optical disc DK.
[0027]
  (1)When recording data
  In this embodiment, the control unit C outputs a drive signal corresponding to the data to be recorded on the optical disc DK to the drive circuit D and improves the recording power based on the drive signal in order to improve the data recording speed on the optical disc DK. The driving circuit D is controlled so that the light beam of the first light source 11 and the second light source 12 are output. As a result, by using the signal supplied from the drive circuit D, the first light source 11 and the second light source 12 emit light, and the light beams output from the light sources 11 and 12, that is, light beams having wavelengths of 660 nm and 780 nm. Both are incident on the first beam splitter 13 and the second beam splitter 14, reflected by both the beam splitters 13 and 14, and irradiated on the objective lens of the actuator unit 15.
[0028]
  FIG. 2 shows the relationship between the focused spot appearing on the optical disc DK and the energy distribution of the light beam in the focused spot. In the figure, each position on the focused spot is associated with the horizontal axis on the graph.
[0029]
  In this case, the radii r of both focused spots with wavelengths of 660 nm and 780 nm are respectively
    r = (k × λ) / NA (formula 1)
Will be shown. However, in (Equation 1), “λ” indicates the wavelength, and “NA” indicates the numerical aperture of the objective lens. In the case of the present embodiment, since any light beam is incident on the same objective lens and is focused on the optical disk DK, the beam radius is determined substantially depending on the wavelength ratio. A 660 nm focused spot is formed with a radius of about 80% within the 780 nm focused spot.
[0030]
  Since the energy distribution for both the focused spots follows a Gaussian distribution, in the state where both spots are completely coincident with each other at the center point, the sum of the energy amounts at the respective points on the optical disk DK is determined from the principle of superposition of light. The amount of light beam energy at. For this reason, it is possible to increase the amount of energy of the light beam that can be irradiated onto the optical disc DK by setting the state where both beams are irradiated.
[0031]
  However, when the optical disk DK is actually irradiated with both light beams of 780 nm and 660 nm, it is considered that spherical aberration occurs due to the difference in focal length, so that energy loss occurs. For example, both beams are applied to DVD-R. When the light is irradiated, energy can be used with an efficiency of about 70 to 80% at maximum for the light beam of 780 nm.
[0032]
  Note that in a dye-type optical disk DK such as a DVD-R, when the total energy of the irradiated light beam exceeds a predetermined value, dye discoloration occurs and information is recorded (photon mode). Information is recorded when the temperature of the optical disk exceeds a certain value (thermal recording), but in any optical disk DK, recording is performed by improving the light intensity of the light beam applied to the optical disk DK. It becomes possible to improve the speed.
[0033]
  In addition, when a configuration in which a light beam corresponding to two wavelengths is condensed on the optical disk DK is employed in this way and the optical disk DK in accordance with the DVD standard is irradiated with a CD light beam having a wavelength of 780 nm, the 780 nm. There is a possibility that the light beam having the wavelength of not only the groove track to be recorded but also the adjacent groove track is irradiated and phase change and dye discoloration occur. Therefore, when adopting the above configuration, it is necessary to appropriately select a material to be used for the optical disc DK so that information is not recorded in a state where only a light beam having a wavelength of 780 nm is irradiated. Become.
[0034]
  On the other hand, when a light beam is irradiated onto the optical disc DK from both the first light source 11 and the second light source 12, components having different wavelengths (660 nm and 780 nm) are mixed in the reflected light reflected on the optical disc DK. . For this reason, when the reflected light is incident on the photodetector 17, crosstalk occurs as described above, and it may be difficult to perform a normal recording operation. Therefore, in the present embodiment, a configuration in which the wavelength filter 18 is provided on the optical path of the reflected light from the optical disc DK is employed.
[0035]
  The wavelength filter 18 is made of, for example, an EC (Electro Chromic) material, and is configured to transmit only a light beam having a predetermined wavelength among incident light beams under the control of the control unit C. . The EC material is a material that causes an electrochromic phenomenon in which an absorption wavelength reversibly changes depending on an applied voltage, and there are two systems, an organic system and an inorganic system. Examples of inorganic EC materials include cathode EC (colored by reduction) such as WO3 (tungsten trioxide) and MoO3 (molybdenum trioxide) using electroabsorption reaction, Prussian blue (KxFeyFez (CN) 6), Ni There are anodic ECs (colored by oxidation) such as (OH) n, and organic EC materials include functional polymers such as polyphenazacillin used as organic EL (Electro Luminescent) materials.
[0036]
  FIG. 3 shows a configuration example of the wavelength filter 18 when inorganic EC is used, and FIG. 4 shows a configuration example of the wavelength filter 18 when organic EC is used.
[0037]
  First, in FIG. 3, reference numeral 101 denotes a substrate, which is made of a highly permeable base material such as SiO2 (silicon dioxide). A transparent electrode 102 is formed on the substrate 101, and an EC layer 103 is formed on the transparent electrode 102 by forming a film by a method such as a sol-gel method, a pulling method, or vapor deposition, followed by baking. Further, a transparent electrode 104 is further laminated on the EC layer 103. As a result, the electrochromic layer 103 is sandwiched between the transparent electrodes 102 and 104. The transparent electrodes 102 and 104 provided on the wavelength filter 18 are connected to the control unit C, respectively, and the control unit C generates an electric potential difference between the electrodes 102 and 104 to absorb the EC layer 103. The wavelength is reversibly changed.
[0038]
  In designing the wavelength filter 18, it is desirable to provide a steep light absorption characteristic between 660 nm and 780 nm. For example, in the case of using Prussian blue as the EC layer 1803, by changing the potential difference of 0.2V, the color changes from colorless to blue and further from blue to green with a potential difference of 1.0V. Therefore, the absorption wavelength can be adjusted to 780 nm or 660 nm by changing the potential difference, and the required filter characteristics can be obtained at a low voltage by selecting an appropriate film pressure. Further, depending on the material used, a plurality of EC layers 1803 formed of different EC materials may be stacked to increase the light beam absorptance of each wavelength.
[0039]
  Next, when organic EC is used, the wavelength filter 18 is configured by bonding two transparent substrates 201 and 204 with a gap therebetween and filling the organic EC material 203 between the two substrates. Transparent electrodes 202 and 205 are formed on opposite surfaces of the transparent substrates 201 and 204, respectively. The electrodes 202 and 205 are connected to the control unit C, and the control unit C generates a potential difference between the electrodes 202 and 205. As a result, the absorption wavelength in the organic EC material 203 is reversibly changed.
[0040]
  Here, when the wavelength filter 18 is employed, a light beam reflected by the wavelength filter 18 is generated in addition to the light beam transmitted and absorbed. Therefore, if the wavelength filter 18 is installed at an angle with the incident axis of the light beam as a normal line, the light beam reflected on the wavelength filter 18 may stray on the optical axis. Therefore, the wavelength filter 18 needs to be installed at a predetermined angle θ with respect to the incident axis of the light beam so that no reflected light is generated on the incident in the filter 18.
[0041]
  In addition, if the wavelength filter 18 is installed closer to the actuator unit 15 than the first beam splitter 13 and the second beam splitter, absorption or reflection occurs before the light beams output from both light sources are applied to the optical disk DK. In order to generate | occur | produce, it is necessary to always install a wavelength filter in the photodetector 17 side rather than both the beam splitters 13 and 14. FIG.
[0042]
  By configuring the wavelength filter 18 as described above, in the information recording / reproducing apparatus RP according to the present embodiment, for example, when information is recorded on a DVD-RW, the light beam reflected by the optical disc DK has a wavelength of 780 nm. A light beam having a wavelength is absorbed and reflected by the wavelength filter 18, and only the light beam having a wavelength of 660 nm passes through the wavelength filter 18 and is received by the photodetector 17. Then, according to the light beam, signals necessary for the RF signal, tracking servo, and focus servo are obtained according to the amount of light received by the photodetector 18.
[0043]
  (2)During data playback
  On the other hand, when reproducing information recorded on the optical disc DK, the control unit C causes only the light source corresponding to the standard of the optical disc DK to be reproduced to emit light. For example, when the optical disc DK to be reproduced is compatible with the CD standard, the control unit C supplies a drive signal to the first light source 11 to cause the first light source 11 to emit light. When the optical disk DK is compatible with the DVD standard, a drive signal is supplied to the second light source 12 to cause the second light source 12 to emit light.
[0044]
  Further, how to control the wavelength filter 18 at the time of reproduction of the optical disk DK is arbitrary, and at the time of reproduction, the transmittance may be controlled to the maximum state, or the optical disk DK to be reproduced may be controlled. The absorption wavelength may be changed according to the standard.
[0045]
  In the above embodiment, the present invention has been described with respect to the case where two types of light sources are provided. However, the types of light sources are not limited thereto. Specifically, in addition to a first light source for recording / reproducing on a DVD and a second light source for recording / reproducing on a CD, a light beam having a wavelength of 405 nm is used for recording / reproducing on a Blu-ray disc. The present invention can also be applied to an apparatus including a third light source capable of output. In this case, as the design of the light absorption characteristic of the wavelength filter 18, it is necessary to set the light absorption characteristic with respect to the wavelength of the laser light emitted from at least two types of the first to third light sources.
[0046]
  Further, write-once recording media (dye discs) such as DVD-R and CD-R have a wavelength dependency of recording performance depending on the dye used in the medium, and have a wavelength other than the wavelength suitable for writing. There is a possibility that efficient writing cannot be performed even if light is irradiated. Specifically, laser light with a wavelength of 660 nm is appropriate for writing on a DVD-R, and sufficient writing performance may not be obtained even when laser light with a wavelength of 780 nm is simultaneously irradiated. Therefore, when writing to such a recording medium, a single light source (laser light having a wavelength most suitable for the recording medium to be written is irradiated without simultaneously turning on the light sources. Recording may be performed using only a possible light source. In this case, it is preferable that the control unit C detects the type of the recording medium that it is going to write, and determines whether or not laser light irradiation is necessary for each of the plurality of light sources in accordance with the detection result.
[0047]
  Conversely, rewritable recording media (phase change disks) such as DVD-RW and DVD-RAM have low wavelength-dependent characteristics of recording performance and can be written by irradiating with a sufficient amount of light. It is desirable to use it. In this case, in order to secure thermal energy necessary for writing to the recording medium, it is desirable to increase the distribution ratio of the driving current of the light source to the light source capable of irradiating laser light having a short wavelength.
[0048]
  As described above, the information recording / reproducing apparatus RP according to the present embodiment has the optical pickup PU that collects the light beam output from the light source on the optical disk DK and receives the reflected light from the optical disk DK. The pickup PU outputs, for example, a first light source 11 that outputs a light beam having a wavelength of 660 nm, and a light beam having a wavelength of 780 nm, for example, to the same optical path as the light beam output from the first light source. A second light source 12, a photodetector 17 that receives the reflected light of the light beam reflected by the optical disc DK and outputs a signal corresponding to the amount of received light, and an optical path of reflected light from the optical disc DK to the photodetector 17 are incident A wavelength filter 18 that controls transmission of the light beam, and both the first light source 11 and the second light source 12, When a light beam is output from either one or both of the light sources 11 and 12, and when both light beams having a wavelength of 660 nm and 780 nm are output, the wavelength filter 18 is controlled to control the light beam having a wavelength of 780 nm. And a control unit C that restricts transmission.
[0049]
  With this configuration, in an environment where light beams are output from both the first light source and the second light source, the control unit C controls the wavelength filter 18 and has a wavelength of 660 nm output from the first light source 11. Only the light beam is transmitted through the wavelength filter 18. As a result, only the light beam having a wavelength of 660 nm is received by the photodetector 17. Therefore, for example, when recording data recorded on the optical disc DK, it is possible to output a light beam from both the first light source 11 and the second light source 12, and to increase the total amount of energy of the light beam irradiated to the optical disc DK. In addition, even when both the light sources 11 and 12 are turned on, for example, only a light beam having a wavelength of 660 nm can be made incident on the photodetector 17, so that the recording speed of an optical disc such as a DVD-R can be increased. It is possible to improve the data and to reliably record and reproduce data.
[0050]
  In the information recording apparatus RP according to the present embodiment, the wavelength filter 18 includes the electrochromic layer 103 or 203 that changes the wavelength of the light beam that can be transmitted according to the applied voltage value, and the voltage applied to the electrochromic layer 103 or 203. And the control unit C changes the voltage value applied to the transparent electrode to vary the transmission wavelength of the wavelength filter 18, thereby transmitting a light beam having a wavelength of 780 nm. It is the structure which restricts.
[0051]
  According to this configuration, it is possible to limit the transmission of a light beam having a wavelength of 780 nm only by controlling the voltage applied to the electroluminescent layer 103 or 203. Therefore, the crosstalk in the photodetector 17 can be achieved while adopting a simple configuration. Can be prevented.
[0052]
  Furthermore, in the information recording / reproducing apparatus RP according to the present embodiment, the control unit C, for example, controls only the first light source 11 to output a light beam having a wavelength of 660 nm when reproducing the data recorded on the optical disc DK. On the other hand, when recording data on the optical disc DK, both the first light source 11 and the second light source 12 are controlled to output, for example, both light beams having wavelengths of 660 nm and 780 nm.
[0053]
  For this reason, it is possible to increase the total energy of the light beam irradiated onto the optical disc DK for data recording while enabling reliable reproduction of the data recorded on the optical disc DK.
[0054]
  Further, in the information recording / reproducing apparatus RP according to the present embodiment, the wavelength filter 18 is installed with a predetermined angle with respect to the optical path of the reflected light from the optical disk DK. For this reason, even when a light beam reflected by the wavelength filter 18 is generated, stray light on the optical axis can be prevented.
[0055]
  In the above-described embodiment, the example in which the wavelength filter 18 is configured by the EC material has been described. However, the wavelength filter 18 is configured by using a material whose transmittance can be changed by temperature, such as a cholestic liquid crystal, and the control unit By controlling the voltage supplied from C, a light beam having one of the wavelengths may be transmitted.
[0056]
  In the above embodiment, the apparatus RP for recording and reproducing information with respect to the optical disc DK corresponding to both the CD and DVD standards has been described. For example, the Blu-ray disc and CD or the Blu-ray disc and DVD standards are supported. An apparatus for recording and reproducing information with respect to the optical disc DK can also be realized by the same configuration as described above.
[0057]
  Furthermore, in the present embodiment, both the first beam splitter 13 and the second beam splitter 14 are directly irradiated with the light beams output from the first light source 11 and the second light source 12. However, a diffraction grating is installed between the light source and the beam splitter, and the light beam output from the first light source 11 or the second light source 12 is divided into a main beam (0th order diffracted light) and a sub beam (± 1st order diffracted light). Thereafter, the first beam splitter 13 and the second beam splitter 14 may be irradiated. However, when such a configuration is adopted, the photodetector 17 is provided with a region for receiving the main beam, and the region is divided into four parts, and the sub-beams are provided on the left and right of the region for receiving the main beam. It is necessary to provide an area for receiving light. In addition, the area for receiving the sub beam is further divided into left and right parts, so that tracking servo and focus servo using the sub beam can be performed.
[0058]
  Furthermore, in the information recording / reproducing apparatus RP according to the present embodiment, the example in which the control unit C and the drive circuit D are configured by a device such as a CPU separate from the optical pickup PU has been described, but these are integrated with the optical pickup PU. You may make it comprise.

Claims (7)

An optical pickup that focuses a light beam output from a light source on an information recording medium and receives reflected light from the information recording medium,
A first light source that outputs a first light beam having a first wavelength;
A second light source that outputs a second light beam having a second wavelength different from the first wavelength;
A light receiving unit that receives the reflected light reflected by the information recording medium and outputs a signal corresponding to the amount of received light;
A filter that is installed on an optical path of the reflected light from the information recording medium to the light receiving unit and controls transmission of the incident second light beam;
Light source control means for controlling both the first light source and the second light source and outputting either one or both of the first and second light beams;
Filter control means for controlling the filter to limit transmission of the second beam when both the first and second light beams are output;
Detecting means for determining the type of the information recording medium;
With
The light source control means determines the presence or absence of the output of the light beam from the first light source and the second light source according to the detection result of the detection means,
When the information recording medium detected by the detection means is a dye-type information recording medium, the light source control means outputs the light beam only from a light source capable of outputting a laser beam having a wavelength suitable for the information recording medium. An optical pickup characterized by that. The filter is
A light-absorbing layer that varies the wavelength of the light beam that can be transmitted according to the applied voltage value;
An electrode for applying a voltage to the light absorption layer,
The filter control means limits the transmission of the second light beam by changing a transmission wavelength of the filter by changing a voltage value applied to the electrode. Optical pickup. The light source control means controls only the first light source to output the first light beam during reproduction of the information recording medium, and outputs both the first light source and the second light source during information recording on the information recording medium. 3. The optical pickup according to claim 1, wherein both of the first and second light beams are output by controlling the first and second light beams. 4. 4. The optical pickup according to claim 1, wherein the filter is installed with a predetermined angle with respect to the optical path of the reflected light. Having detection means for determining the type of the information recording medium;
2. The optical pickup according to claim 1, wherein the light source control unit changes an output ratio of the light beam from the first light source and the second light source in accordance with a detection result of the detection unit. When the information recording medium detected by the detection means is a phase change information recording medium, an output ratio of the laser light from a light source capable of outputting a laser light having a short wavelength among the first light source and the second light source, The optical pickup according to claim 1, wherein the optical pickup is configured to have a larger output ratio than the laser light from another light source. An information recording / reproducing apparatus including an optical pickup that focuses a light beam output from a light source on an information recording medium and receives reflected light from the information recording medium,
The optical pickup is
A first light source that outputs a first light beam having a first wavelength;
A second light source that outputs a second light beam having a second wavelength different from the first wavelength;
A light receiving unit that receives the reflected light reflected by the information recording medium and outputs a signal corresponding to the amount of received light;
A filter that is installed on an optical path of the reflected light from the information recording medium to the light receiving unit and controls transmission of the incident second light beam;
Light source control means for controlling both the first light source and the second light source and outputting either one or both of the first and second light beams;
Filter control means for controlling the filter to limit transmission of the second beam when both the first and second light beams are output;
Detecting means for determining the type of the information recording medium;
With
The light source control means determines the presence or absence of the output of the light beam from the first light source and the second light source according to the detection result of the detection means,
When the information recording medium detected by the detection means is a dye-type information recording medium, the light source control means outputs the light beam only from a light source capable of outputting laser light having a wavelength suitable for the information recording medium. An information recording / reproducing apparatus.

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