WO2007026548A1

WO2007026548A1 - Optical pickup device, information recording device and information reproducing device

Info

Publication number: WO2007026548A1
Application number: PCT/JP2006/316157
Authority: WO
Inventors: Naoharu Yanagawa; Akira Shirota
Original assignee: Pioneer Corporation
Priority date: 2005-08-31
Filing date: 2006-08-17
Publication date: 2007-03-08

Abstract

Disclosed is an optical pickup device (10) comprising a light source (11) for irradiating a recording surface of an information recording medium (50), a light intensity-controlling means (26) for changing the light intensity of emitted light, a first filter (13) arranged on the optical path of the emitted light for controlling the amount of emitted light transmitting therethrough, and a first filter-controlling means (27) for controlling the first filter so that the amount of emitted light transmitting therethrough is regulated in accordance with the intensity of the emitted light.

Description

Specification

Optical pickup device, information recording device, and information reproducing device

Technical field

The present invention relates to an optical pickup device used for recording and reproducing data on an information recording medium such as an optical disk, and an information recording device and an information reproducing device including the optical pickup device.

Background art

[0002] Conventionally, in an information recording / reproducing apparatus for recording and reproducing data on an optical disc such as a CD (Compact Disc) or a DVD (Digital Versatile Disc), the convenience of the user is improved, or From the standpoint of discriminating from other products, the recording speed of data on optical discs such as DVD-R has been improved.

[0003] Here, an optical disc such as DVD-R or DVD-RW has a constant temperature on the optical disc when the total energy of the light beam irradiated per unit time exceeds a predetermined threshold. When the value exceeds the value, thermal decomposition or phase change of the dye occurs, whereby various data are recorded. For this reason, if the rotational speed of the optical disk is increased to increase the recording speed, data cannot be recorded unless the amount of energy of the light beam applied to the optical disk is increased. Therefore, in order to improve the recording speed, it is essential to increase the amount of energy of the light beam output from the light source.

Disclosure of the invention

Problems to be solved by the invention

[0004] As of August 2005, the recording speed of 8x speed recording and 16x speed recording of single-layer discs has been commercialized and double-layer discs are being developed. At such a recording speed, it is necessary to use a high-power laser to increase the amount of energy of the light beam!]. On the other hand, even when a high-power laser is used, it is necessary to weaken the amount of energy of the light beam during reproduction to such an extent that data recorded on the optical disk is not erased. Specifically, the amount of light beam energy during reproduction (ie, reproduction power) is determined by the optical beam during recording. It is necessary to weaken from 1Z20 times to 1Z30 times the amount of energy (ie, recording power). However, since a high-power laser is used, there is a technical problem that the operation of the high-power laser becomes unstable if the energy amount of the light beam during reproduction is weakened. Specifically, there is a technical problem that, for example, RIN (Relative Intensity Noise) deteriorates by weakening the amount of energy of the light beam.

[0005] As described above, if the laser is set to a high output in accordance with the improvement of the recording speed, inconvenience occurs in the operation at the time of reproduction.

[0006] The present invention has been made in view of, for example, the above-described conventional problems. For example, an optical pickup device capable of performing a suitable recording operation and reproducing operation, an information recording device, and an information reproducing device. It is an object to provide an apparatus.

Means for solving the problem

[0007] (Optical pickup device)

In order to solve the above-described problems, an optical pickup device of the present invention includes a light source that irradiates a recording surface of an information recording medium with emitted light, a light intensity control unit that changes the light intensity of the emitted light, and the output light. A first filter that is disposed on the optical path of the emitted light and controls the transmission amount of the incident outgoing light; and the first filter that controls the transmission amount of the outgoing light according to the light intensity of the outgoing light. First filter control means for controlling

According to the optical pickup device of the present invention, the emitted light emitted from the light source is irradiated onto the recording surface of the information recording medium. The intensity of the emitted light is controlled by the operation of the light intensity control means. For example, when recording data on an information recording medium, the first light that is relatively strong (or relatively large) capable of forming a recording mark or recording pit on the recording surface of the information recording medium. Intensity and light source power are also emitted. Or, for example, when reproducing data recorded on an information recording medium, the recording mark or recording pit formed on the recording surface of the information recording medium is not destroyed or erased. The emitted light is emitted from the light source with a second light intensity that is relatively weak (or relatively small).

In the present invention, in particular, the emitted light is incident on the recording surface of the information recording medium after entering the first filter. The first filter can increase or decrease the transmission amount of outgoing light incident on the first filter. How much outgoing light is transmitted depends on the operation of the first filter control means. More controlled. That is, the transmission amount of the first filter is controlled by the operation of the first filter control means.

[0010] For this reason, for example, when recording data on an information recording medium, the emitted light is irradiated with the light source force with a relatively strong first light intensity. However, the recording mark is recorded on the recording surface of the information recording medium. In order to form recording pits, it is necessary to irradiate the recording surface of the information recording medium with emitted light while maintaining high light intensity. Therefore, for example, when recording data on an information recording medium, the recording surface of the information recording medium is irradiated with emitted light having a strong light intensity that can suitably form a recording mark or recording pit. The transmission amount of the first filter is relatively increased tl (for example, the transmittance is set to 100%).

[0011] For example, when reproducing data recorded on an information recording medium, the emitted light is irradiated with a light source force with a relatively weak second light intensity. However, in order to record data on the information recording medium, it is necessary to emit the emitted light from the light source with a relatively strong first light intensity. In particular, the first light intensity tends to increase with the increase in recording speed, which has been developed in recent years. For this reason, in order to emit outgoing light with the first light intensity, it may be necessary to use a light source having a relatively large output. In this case, the second light intensity needs to be increased to some extent in order to reduce the noise of the emitted light, which also causes the light source power, which causes the recording characteristics or the reproduction characteristics to deteriorate, relative to the emitted light. is there. On the other hand, when the second light intensity is increased to some extent, the recording marks or recording pits formed on the recording surface of the information recording medium may be destroyed or erased. Therefore, in the present invention, the light intensity of the outgoing light after passing through the first filter is reduced by relatively reducing the transmission amount of the first filter (for example, by making the transmittance smaller than 100%). The intensity of the emitted light emitted from the light source can be reduced. As a result, it is possible to irradiate the recording surface of the information recording medium with a certain amount of emitted light that is formed on the recording surface of the information recording medium without destroying or erasing the recording pits or the recording pits. In addition, the generation of noise in the emitted light can be suitably reduced relative to the emitted light.

As a result, according to the optical pickup device of the present invention, a suitable recording operation and reproducing operation can be performed.

In one aspect of the optical pickup device of the present invention, the light intensity control means includes the emitted light. The light intensity of the emitted light is controlled such that the noise of the emitted light is equal to or less than a predetermined first threshold value, and the first filter control means is configured such that the light intensity of the emitted light on the recording surface is a predetermined second threshold value. The first filter is controlled to be as follows.

[0014] According to this aspect, the first threshold value and the second threshold value that can ensure a suitable recording operation and reproduction operation are set, and the output of the light source power is emitted based on the set first threshold value. The light intensity of the incident light is controlled, and the transmission amount of the first filter is controlled based on the set second threshold value. Therefore, a suitable recording operation and reproducing operation can be performed.

[0015] In the aspect of the optical pickup device in which the light intensity of the emitted light is controlled so that the noise of the emitted light is equal to or less than the first threshold as described above, the first threshold is recorded on the information recording medium, It may be configured to be the upper limit value of the noise range so as not to adversely affect the reproduction of data.

With this configuration, it is possible to suitably reduce the occurrence of noise in the emitted light, and as a result, it is possible to perform a suitable recording operation and reproducing operation. As another means for removing stray light, an AR (Anti-Reflection) coating may be applied to the surface of the first filter.

[0017] In the aspect of the optical pickup device in which the first filter is controlled so that the power of the emitted light is equal to or lower than the second threshold as described above, the second threshold is the value of the data recorded on the information recording medium. You may comprise so that it may be the upper limit of the range of the light intensity on the said recording surface suitable for reproduction | regeneration.

[0018] With this configuration, it is formed on the recording surface of the information recording medium !, it is a recording mark! /, Or the recording pit is not destroyed or erased. Irradiation can be applied to the recording surface of the information recording medium, and as a result, suitable recording and reproducing operations can be performed.

[0019] In another aspect of the optical pickup device of the present invention, the first filter control means relatively determines a transmission amount of the first filter when reproducing the data recorded on the information recording medium. The first filter is controlled so as to relatively increase the transmission amount of the first filter when data is recorded on the information recording medium. In other words, when the first filter control means records the data on the information recording medium, the transmission amount of the first filter when reproducing the data recorded on the information recording medium The first filter is controlled to be smaller than the transmission amount of the first filter.

[0020] According to this aspect, the transmission amount of the first filter is relative to that formed on the recording surface of the information recording medium! During reproduction in which recording marks or recording pits are required not to be destroyed or erased. Decrease. For this reason, the light intensity of the emitted light is weakened. As a result, while the generation of noise of the emitted light is suitably reduced, it is formed on the recording surface of the information recording medium and does not destroy or erase the recording pits or the recording pits. The recording surface of the information recording medium can be irradiated with emitted light having intensity. On the other hand, the amount of transmission through the first filter is relatively increased during recording in which recording marks or recording pits are required to be formed by applying a thermal change to the recording surface of the information recording medium. For this reason, the light intensity of the emitted light is not weakened or excessively weakened, and as a result, the emitted light having a light intensity sufficient to form a recording mark or a recording pit on the recording surface of the information recording medium is obtained. The recording surface of the information recording medium can be irradiated.

[0021] In another aspect of the optical pickup device of the present invention, the light intensity control means changes the light intensity of the emitted light according to recording and reproduction of data on the information recording medium.

[0022] According to this aspect, a suitable recording operation and reproducing operation can be performed.

[0023] In another aspect of the optical pickup device of the present invention, the first filter includes an absorption layer whose absorption wavelength varies depending on a value of an applied voltage, and an electrode that applies the voltage to the absorption layer. The first filter control means controls the first filter by changing a value of the voltage applied to the electrode.

[0024] According to this aspect, the transmission amount of the first filter can be increased or decreased by changing the voltage applied to the light absorption layer.

[0025] In another aspect of the optical pickup device of the present invention, the first filter includes a liquid crystal layer including a liquid crystal element whose molecular arrangement changes according to a value of an applied voltage, and the voltage applied to the liquid crystal layer. The first filter control means controls the first filter by changing the value of the voltage applied to the electrode.

[0026] According to this aspect, the transmission amount of the first filter can be increased or decreased by changing the voltage applied to the liquid crystal layer. In another aspect of the optical pickup device of the present invention, the first filter is arranged with a predetermined angle with respect to the optical path of the emitted light.

[0028] According to this aspect, it is possible to suitably eliminate stray light generation factors that can be generated by being reflected in the first filter and emitted light force incident on the first filter.

Another aspect of the optical pickup device of the present invention is a light receiving means for receiving reflected light from the recording surface and a transmission amount of the reflected light that is disposed on an optical path of the reflected light and incident. And a second filter control means for controlling the second filter so as to control the transmission amount of the reflected light according to the light intensity of the reflected light.

[0030] Generally, when the light intensity of the emitted light at the time of recording is increased (in other words, when the amount of energy of the emitted light at the time of recording is increased), the light is received by a light receiving means such as a photodetector during reproduction. The difference between the amount of reflected light and the amount of light received by the light receiving means during recording increases. For this reason, there is a possibility that the reflected light cannot be received normally by the light receiving means. For example, if a light receiving means is designed that can accurately receive a light reception signal from the reflected light during playback, the light intensity of the reflected light during recording increases and exceeds the dynamic range of the light receiving means. It is difficult or impossible to receive light normally by the means.

[0031] Therefore, a filter is provided on the optical path of the reflected light incident on the light receiving means to reduce the light intensity of the reflected light incident on the light receiving means, thereby reducing the amount of received light when the recording speed is increased. A measure to make adjustments can be considered. However, in this case, it becomes difficult to ensure the SZN ratio during data reproduction. That is, when a filter is provided on the optical path of the reflected light, if the light intensity is reduced only during recording, the light intensity of the reflected light is reduced during reproduction, and it is difficult to secure the level of the received light signal. It becomes.

[0032] On the other hand, the light receiving means is configured using an OEIC in which various circuits such as a light receiving element and an amplifier circuit are integrated, and the amplification factor of the amplifier circuit is switched at the time of data recording or data reproduction. A possible measure is to adjust the amount of light received when the recording speed is increased by making it possible to receive reflected light during playback. However, in this case, since the light intensity of the reflected light is not reduced before light reception, it is possible to secure the level of the light reception signal during reproduction, but the structure of the light receiving means is complicated. And The control method itself is complicated.

[0033] However, according to this aspect, since the second filter capable of controlling the transmission amount is disposed on the optical path of the reflected light, the light intensity of the reflected light is selectively reduced during data recording. Can be made. As a result, the SZN ratio of the light receiving signal that is the output of the light receiving means can be suitably secured. Since it is not necessary to configure the light receiving means using OEICs that have various circuits such as light receiving elements and amplifier circuits, the circuit configuration can be made relatively simple. Therefore, even when the data recording speed is increased, a suitable recording operation and reproducing operation can be performed.

[0034] In the aspect of the optical pick-up device including the light receiving means, the second filter, and the second filter control means as described above, the second filter control means has the light intensity of the reflected light incident on the light receiving means. The second filter may be controlled so as to be within the dynamic range of the light receiving means.

[0035] With this configuration, the SZN ratio of the light receiving signal that is the output of the light receiving means can be suitably ensured, and as a result, a suitable recording operation and reproducing operation can be performed.

[0036] In the aspect of the optical pickup apparatus including the light receiving means, the second filter, and the second filter control means as described above, the second filter control means has the light intensity of the reflected light incident on the light receiving means. Configure to control the second filter so that it is approximately constant.

[0037] With this configuration, it is possible to favorably secure the SZN ratio of the received light signal that is the output of the light receiving means, and as a result, it is possible to perform a suitable recording operation and reproducing operation.

[0038] As described above, in the aspect of the optical pick-up device including the light receiving means, the second filter, and the second filter control means, the second filter control means is configured such that the light intensity of the reflected light is relatively strong. The second filter may be controlled so that the transmission amount is relatively decreased and the transmission amount is relatively increased when the light intensity of the reflected light becomes relatively weak. .

[0039] With this configuration, the intensity of the reflected light incident on the light receiving means can be made substantially constant. For this reason, the SZN ratio of the light receiving signal that is the output of the light receiving means can be suitably ensured, and as a result, a suitable recording operation and reproducing operation can be performed. [0040] In the aspect of the optical pickup apparatus comprising the light receiving means, the second filter, and the second filter control means as described above, the second filter control means, when recording data on the information recording medium, The second filter is controlled so that the amount of reflected light transmitted corresponding to the space portion of the data is relatively increased and the amount of reflected light transmitted corresponding to the mark portion of the data is relatively decreased. It may be configured as follows.

[0041] With this configuration, the intensity of the reflected light incident on the light receiving means can be kept within the dynamic range of the light receiving means or can be made substantially constant. For this reason, the SZN ratio of the light receiving signal that is the output of the light receiving means can be suitably secured, and as a result, a suitable recording operation and reproducing operation can be performed.

[0042] As described above, in the aspect of the optical pick-up device including the light receiving means, the second filter, and the second filter control means, the second filter control means records data when recording data on the information recording medium. The second filter may be controlled so as to relatively increase or decrease the transmission amount of the reflected light in synchronization with the reverse phase of the recording pulse used for emitting the emitted light for use. Yo ...

[0043] With this configuration, the intensity of the reflected light incident on the light receiving unit can be kept within the dynamic range of the light receiving unit or can be made substantially constant. For this reason, the SZN ratio of the light receiving signal that is the output of the light receiving means can be suitably secured, and as a result, a suitable recording operation and reproducing operation can be performed.

[0044] In the aspect of the optical pickup device including the light receiving means, the second filter, and the second filter control means as described above, the second filter includes a light absorbing layer whose absorption wavelength varies depending on the value of an applied voltage, An electrode for applying the voltage to the light absorption layer, and the second filter control means controls the second filter by changing a value of the voltage applied to the electrode. You can configure it.

[0045] With this configuration, the transmission amount of the second filter can be increased or decreased by changing the voltage applied to the light absorption layer.

[0046] In the aspect of the optical pickup apparatus including the light receiving means, the second filter, and the second filter control means as described above, the second filter includes a liquid crystal element whose molecular arrangement changes depending on the value of the applied voltage. A liquid crystal layer, and an electrode for applying the voltage to the liquid crystal layer. The second filter control means may be configured to control the second filter by changing a value of the voltage applied to the electrode.

With this configuration, the transmission amount of the second filter can be increased or decreased by changing the voltage applied to the liquid crystal layer.

[0048] In the aspect of the optical pick-up device including the light receiving means, the second filter, and the second filter control means as described above, the second filter has a predetermined angle with respect to the optical path of the reflected light. It can be configured to be arranged.

[0049] With this configuration, stray light generation factors that can be generated by the outgoing light incident on the second filter being reflected in the second filter can be suitably eliminated.

[0050] (Information recording device)

In order to solve the above problems, an information recording apparatus of the present invention includes a light source that irradiates a recording surface of an information recording medium with emitted light, a light intensity control unit that changes a light intensity of the emitted light, A first filter disposed on the optical path for controlling a transmission amount of the incident outgoing light, and a first filter for controlling the transmission amount of the outgoing light according to the light intensity of the outgoing light. First filter control means for controlling, and recording means for recording data on the information recording medium. In other words, the information recording apparatus of the present invention includes the above-described optical pickup apparatus of the present invention (including various aspects thereof) and recording means for recording data on the information recording medium.

[0051] According to the information recording apparatus of the present invention, it is possible to record data on the information recording medium while enjoying the same benefits as the benefits of the optical pickup device of the present invention described above.

Incidentally, in response to the various aspects of the optical pickup apparatus of the present invention described above, the information recording apparatus of the present invention can also adopt various aspects.

[0053] (Information reproduction device)

In order to solve the above problems, an information reproducing apparatus of the present invention includes a light source that irradiates a recording surface of an information recording medium with emitted light, a light intensity control unit that changes a light intensity of the emitted light, A first filter disposed on the optical path for controlling a transmission amount of the incident outgoing light, and a first filter for controlling the transmission amount of the outgoing light according to the light intensity of the outgoing light. First filter control means for controlling, and recorded on the information recording medium Reproducing means for reproducing the received data. In other words, the information reproducing apparatus of the present invention includes the above-described optical pickup apparatus of the present invention (including various aspects thereof) and reproducing means for reproducing data recorded on the information recording medium.

According to the information recording apparatus of the present invention, it is possible to record data on the information recording medium while enjoying the same benefits as the benefits of the optical pickup device of the present invention described above.

[0056] These effects and other advantages of the present invention will become apparent from the embodiments described below.

As described above, according to the optical pickup device of the present invention, the light source, the light intensity control means, the first filter, and the first filter control means are provided. Therefore, a suitable recording operation and reproducing operation can be performed.

[0058] According to the information recording apparatus of the present invention, the light source, the light intensity control means, the first filter, the first filter control means, and the recording means are provided. According to the information reproducing apparatus of the present invention, the light source and

A light intensity control means, a first filter, a first filter control means, and a regeneration means. Therefore, a suitable recording operation or reproducing operation can be performed.

Brief Description of Drawings

FIG. 1 is a block diagram conceptually showing the basic structure of an information recording / reproducing apparatus in a first example.

FIG. 2 is a sectional view conceptually showing a first specific example of the first filter.

FIG. 3 is a sectional view conceptually showing a second specific example of the first filter.

FIG. 4 is a sectional view conceptually showing a third specific example of the first filter.

FIG. 5 is a graph conceptually showing power vs. noise (RIN) characteristics.

FIG. 6 is a block diagram conceptually showing the basic structure of an information recording / reproducing apparatus in a second example.

[Fig. 7] The waveform of the drive signal output from the laser drive circuit to the laser diode during data recording, the transmittance of the second filter, and the waveform of the reflected light received by the photodetector along the time axis. It is the described waveform diagram.

Explanation of symbols [0060] 1, 2 Information recording / reproducing apparatus

10 Optical pickup

11 Laser diode

13 First filter

17 Photo detector

18 Second filter

23 Laser noise measurement circuit

24 CPU

27 First filter control circuit

33 Second filter control circuit

50 optical disc

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best mode for carrying out the present invention will be described in each embodiment in order with reference to the drawings. In the following embodiments, an information recording / reproducing apparatus capable of recording and reproducing data with respect to various optical discs such as CD, DVD, Blu-ray Disc, etc., provided with the embodiments of the optical pickup device of the present invention. Proceed with the explanation.

[0062] (1) First Example

First, the basic configuration of the information recording / reproducing apparatus in the first example will be described with reference to FIG. FIG. 1 is a block diagram conceptually showing the basic structure of the information recording / reproducing apparatus in the first example.

As shown in FIG. 1, an information recording / reproducing apparatus 1 according to the first embodiment includes an optical pickup 10, a photo detector (PD) amplifier 21, a reproducing circuit 22, and a laser noise measuring circuit. 23, a CPU 24, a recording circuit 25, a laser drive circuit 26, a first filter control circuit 27, and a spinner motor 28.

The optical pickup 10 is used to irradiate the optical disc 50 with a light beam and to record and reproduce data on the optical disc 50. In order to realize a powerful function, the optical pickup 10 includes a laser diode 11, a front monitor (FM) 12, a first filter 13, a beam splitter 14, an objective lens 15, and a condenser lens 16. Photo de And a detector 17.

The laser diode 11 constitutes one specific example of the “light source” in the present invention, and irradiates a plurality of types of light beams having different wavelengths based on the drive signal supplied from the laser drive circuit 26. For example, when data is recorded and reproduced on a DVD constituting a specific example of the optical disc 50, the laser diode 11 irradiates a light beam having a wavelength of approximately 660 nm. For example, when data is recorded on and reproduced from a CD constituting a specific example of the optical disc 50, the laser diode 11 irradiates a light beam having a wavelength of approximately 780 nm. For example, when recording and reproducing data on a Blu-ray Disc that constitutes a specific example of the optical disc 50, the laser diode 11 irradiates a light beam having a wavelength of approximately 405 ηm.

[0066] The front monitor 12 includes, for example, a light receiving sensor and the like. The power of the light beam emitted from the laser diode 11 (that is, the light intensity value or the amount of energy of the light beam, which is received by the light receiving sensor or the like). The value according to the quantity) can be measured. The measured power is output to the first filter control circuit 27.

[0067] The first filter 13 is controlled by the first filter control circuit 27, and the amount of transmission of the light beam incident on the first filter 13 (that is, the transmittance for the light beam incident on the first filter 13). ) Can be changed. The specific configuration of the first filter 13 will be described later in detail (see FIGS. 2 to 4).

[0068] The beam splitter 14 reflects 90% of the light beam, which is also incident on the side force of the laser diode 11, to the optical disk 50 and transmits 10%, and enters the optical disk 50 from the side. The light beam (that is, the light reflected from the optical disk 50) is transmitted 100% as it is.

The objective lens 15 emits an incident light beam and irradiates the recording surface of the optical disc 50.

[0070] The condensing lens 16 condenses the light beam transmitted through the beam splitter 14 as it is (that is, the light beam reflected from the optical disk 50), and irradiates the light receiving surface of the photodetector 17. .

[0071] The photodetector 17 constitutes one specific example of the "light receiving means" of the present invention. It is composed of a photodiode, receives the light beam emitted from the condenser lens 16, and outputs a detection signal corresponding to the power of the received light beam to the photodetector amplifier 21.

The photo detector amplifier 21 generates an RF signal from the detection signal output from the photo detector 17, and outputs the RF signal to each of the reproduction circuit 22 and the laser noise measurement circuit 23.

[0073] The reproduction circuit 22 constitutes a specific example of "reproduction means" in the present invention. The RF signal output from the photodetector amplifier 21 is demodulated, decoded, or error-corrected. Or a decoding process or the like to generate a reproduction signal. The reproduction circuit 22 outputs the generated reproduction signal to an external display, a speaker or the like, and as a result, it is reproduced as data power recorded on the optical disc 50, for example, video content, audio content, or other content.

The laser noise measurement circuit 23 measures RIN (Relative Intensity Noise) using the RF signal output from the photodetector amplifier 21. The measured RIN is output to CPU24.

The CPU 24 is connected to each component of the information recording / reproducing apparatus 1 via a bus, and controls the entire information recording / reproducing apparatus 1 by instructing each component element. Usually, software or firmware for the CPU 24 to operate is stored in a memory in the information recording / reproducing apparatus 1.

Further, the CPU 24 determines the power value of the light beam emitted from the laser diode 11 based on RIN output from the laser noise measurement circuit 23. The determined power value is output to the laser drive circuit 26.

The recording circuit 25 constitutes one specific example of “recording means” in the present invention, and corrects errors with respect to recording data input from the outside as data to be recorded on the optical disk 50. A recording signal is generated by performing code addition processing, modulation processing, encryption processing, encoding processing, and the like. The generated recording signal is output to the laser drive circuit 26.

The laser drive circuit 26 constitutes one specific example of the “light intensity control means” of the present invention under the control of the CPU 24, and controls the operation of the laser diode 11. Is output to the laser diode 11. More specifically, when recording data on the optical disc 50, the laser drive circuit 26 uses a predetermined power as a write light or a power (hereinafter referred to as a power value output from the CPU 24). And a recording signal that is irradiated with a light beam while being modulated in accordance with the recording signal output from the recording circuit 25, and outputs it to the laser diode 11. Alternatively, when reproducing the data recorded on the optical disc 50, the laser drive circuit 26 uses a predetermined power as reading light or a power corresponding to a power value output from the CPU 24 (hereinafter referred to as “reproduction power”). T)) Generate a drive signal that is irradiated with the light beam and output it to the laser diode 11.

The first filter control circuit 27 constitutes a specific example of the “first filter control means” of the present invention under the control of the CPU 24, and transmits the light beam incident on the first filter 13. It is configured to control the amount change.

The spindle motor 28 rotates and stops the optical disc 50, and operates when accessing the optical disc 50. More specifically, the spindle motor 28 is configured to rotate and stop the optical disc 50 at a predetermined speed while receiving spindle servo from a servo unit (not shown) or the like.

In the information recording / reproducing apparatus 1 having the above configuration, the light beam emitted from the laser diode 11 is incident on the first filter 13. At this time, the power of the light beam emitted from the laser diode 11 is controlled by the first filter 13, is reflected by the beam splitter 14, enters the objective lens 15, and is condensed on the optical disk 50. When the light beam is collected on the optical disk 50 in this way, the light beam is reflected by the optical disk 50 and then enters the beam splitter 14 via the objective lens 15 again. Transmits through splitter 14. Thereafter, the light enters the condenser lens 16 and is condensed on the photodetector 17 by the condenser lens 16. As a result, the photodetection signal is output from the photodetector 17 to the photodetector amplifier 21, and the RF signal is output from the photodetector amplifier 21 to the reproduction circuit 22.

[0082] When the RF signal is output from the photodetector 17, the CPU 24 reproduces data corresponding to the RF signal when reproducing the data recorded on the optical disc 50. The reproduction circuit 22 is controlled, and the reproduction circuit 22 outputs the data to the outside. On the other hand, when data is recorded on the optical disc 50, the CPU 24 determines the output timing of the drive signal corresponding to the address acquisition and data to be recorded on the optical disc 50 based on this RF signal, for example.

[0083] Next, a specific configuration of the first filter 13 will be described with reference to FIGS. FIG. 2 is a cross-sectional view conceptually showing a first specific example of the first filter 13, and FIG. 3 is a cross-sectional view conceptually showing a second specific example of the first filter 13. FIG. 4 is a sectional view conceptually showing a third specific example of the first filter 13.

First, according to the present embodiment, the first filter 13 can be configured using a material called an EC (Electrochromic) material, for example. This EC material is a material that causes the electochromism phenomenon in which the absorption wavelength reversibly changes depending on the applied voltage. The applied voltage causes the transparent state force to absorb only light of a predetermined frequency and change to a state of each color. It has characteristics. There are two types of EC materials, inorganic and organic. Examples of inorganic EC materials include forces such as W03 (tungsten trioxide) and Mo 03 (molybdenum trioxide) using electroabsorption reaction. There are Sword EC (colored by reduction), Prussian blue (Kx FeyFez (CN) 6), Niodic EC (colored by oxidation) such as Ni (OH) n, and organic EL materials are organic EL (Electro Luminescent) materials There are functional polymers such as polyphenacillin.

As shown in FIG. 2, a first specific example of the first filter 13 (hereinafter referred to as “first filter 13a”) is a highly permeable substrate such as Si02 (acid silicon). A substrate 101 is provided. A transparent electrode 102 is formed on the substrate 101, and an EC layer 103 is formed on the transparent electrode 102 by film formation by a sol-gel method, a pulling method, vapor deposition, or the like, followed by baking. A transparent electrode 104 is further laminated on the EC layer 103. As a result, the EC layer 103 is sandwiched between the transparent electrode 102 and the transparent electrode 104. The transparent electrode 102 and the transparent electrode 104 are each connected to a power source provided in the first filter control circuit 27, and the first filter control circuit 27 is provided between the transparent electrode 102 and the transparent electrode 104. By applying this voltage, the light absorption characteristic (for example, absorption wavelength) in the EC layer 103 is reversibly changed. In other words, the first The transmission amount of the light beam incident on the filter 13a is reversibly changed.

[0086] Since the absorbance in the EC material varies depending on the material to be used, when specifically designing the first filter 13a, the power of the light beam emitted from the laser diode 11 is determined using the first filter 13a. It is preferable to determine the thickness of the EC layer 103, the EC material used for the EC layer 103, the magnitude of the voltage applied to the EC layer 103, etc., depending on how much it is reduced by transmission. .

Next, when an organic EC material is used, as shown in FIG. 3, a second specific example of the first filter 13 (hereinafter referred to as “first filter 13b”) includes two transparent substrates 111 The transparent substrate 114 is bonded with a gap, and an EC layer 113 made of an organic EC material is filled between the transparent substrate 111 and the transparent substrate 114. On the opposing surfaces of the transparent substrate 111 and the transparent substrate 114, a transparent electrode 112 and a transparent electrode 115 are formed. Each of the transparent electrode 112 and the transparent electrode 115 is connected to a power source provided in the first filter control circuit 27, and the first filter control circuit 27 is provided between the transparent electrode 112 and the transparent electrode 115. By applying a predetermined voltage, the light absorption characteristics in the EC layer 113 are reversibly changed. That is, the transmission amount of the light beam incident on the first filter 13b is reversibly changed.

Even in this case, it is necessary to appropriately design the thickness, applied voltage value, and the like of the EC layer 113, as in the EC layer 103 in which the inorganic EC material force is also configured.

[0088] In addition to or instead of using the EC material, the first filter may be configured using a liquid crystal material such as a cholestic liquid crystal. The transmittance of the cholesteric liquid crystal can be changed according to the applied voltage and temperature. Specifically, as shown in FIG. 4, the third specific example of the first filter 13 (hereinafter referred to as “first filter 13c”) includes two transparent substrates 121 and 124 with a gap. The liquid crystal layer 123 is also filled between the transparent substrate 121 and the transparent substrate 124, and the liquid crystal material force is also filled. A transparent electrode 122 and a transparent electrode 125 are formed on the opposing surfaces of the transparent substrate 121 and the transparent substrate 124. Each of the transparent electrode 122 and the transparent electrode 125 is connected to a power source provided in the first filter control circuit 27, and the first filter control circuit 27 is connected between the transparent electrode 122 and the transparent electrode 125. By applying a predetermined voltage to the liquid crystal layer 123, Thus, the alignment characteristics of the liquid crystal molecules contained in the liquid crystal material are reversibly changed. That is, the transmission amount of the light beam incident on the first filter 13c is reversibly changed. Even in this case, it is necessary to appropriately design the thickness, applied voltage value, etc. of the liquid crystal layer 123 as in the case of the EC layer 103 including the inorganic EC material force and the EC layer 113 including the organic EC material force. It is.

[0089] The information recording / reproducing apparatus 1 of the present embodiment having such a configuration operates as follows.

First, when data is recorded on the optical disc 50, a force in which the light beam is irradiated from the laser diode 11 with a recording power stronger than the reproduction power. Recording marks or recording pits are formed on the recording surface of the optical disc 50. In order to achieve this, it is necessary to irradiate the recording surface of the optical disc 50 with a light beam while maintaining a strong power (that is, without reducing or reducing the performance).

Therefore, for example, when data is recorded on the optical disc 50, the transmittance of the first filter 13 is set to, for example, approximately 100%. That is, under the control of the CPU 24, the first filter control unit 27 controls the voltage applied to the first filter 13 so that the transmittance of the first filter 13 is approximately 100%. As a result, the transmission amount of the emitted light of the laser diode 11 force in the first filter 13 is maintained at the maximum state (that is, the transparent state), and the reduction of the light beam power in the first filter 13 is minimized. Is done. As a result, the light beam irradiated from the laser diode 11 is irradiated onto the recording surface of the optical disc 50 with little or no reduction in power at the first filter 13. Thereby, a recording mark or a recording pit can be suitably formed on the recording surface of the optical disc 50. That is, the optical disk 50 can be suitably caused to undergo phase change or thermal decomposition of the dye.

Subsequently, for example, when data recorded on the optical disk 50 is reproduced, the light beam is irradiated from the laser diode 11 with the reproduction power, which is weaker than the recording power. On the other hand, recording power tends to increase with the increase in recording speed, which has been developed in recent years. This is because when the data recording speed to the optical disc 50 is to be increased, the power of the light beam applied to the optical disc 50 per unit time exceeds a predetermined threshold, or In other words, since the temperature on the optical disc 50 needs to be a certain value or more, it is necessary to increase the power of the light beam applied to the optical disc 50. For this reason, in order to irradiate a light beam of recording power from the laser diode 11, it is necessary to use the laser diode 11 having a relatively large output (that is, a high output). In this case, in order to irradiate the optical beam of the reproduction power from the laser diode 11 having a relatively large output, it is necessary to irradiate the light beam in an unstable state before and after the laser oscillation of the laser diode 11 starts. Come out. When a light beam having a relatively high output is weakly emitted from a laser diode 11 having a relatively high output and is irradiated with a light beam having a reproduction power, as shown in FIG. 5, the light beam causes deterioration of the recording characteristics or the reproduction characteristics. There is also the inconvenience that the noise (RIN) increases. On the other hand, when the light beam is irradiated after setting the playback power to a certain extent to avoid irradiating the light beam in an unstable and increased noise (RIN) state, it is formed on the recording surface of the optical disc 50 this time. If the recorded mark V or the recorded pit is destroyed or deleted, there will be inconvenience.

Therefore, for example, when reproducing data recorded on the optical disc 50, the power of the light beam emitted from the laser diode 11 is set to be stronger than the standard reproduction power. By reducing the transmittance of the first filter 13 in accordance with the power of the light beam, all the above inconveniences are eliminated.

[0094] Specifically, under the control of the CPU 24, the laser (RIN) value measured by the laser noise measurement circuit 23 is realized to a value that does not adversely affect recording and reproduction. The power of the light beam emitted from the diode 11 is increased. Here, while directly monitoring the noise (RIN) measured by the laser noise measurement circuit 23, the value of the monitored noise (RIN) does not adversely affect recording and playback. The power of the light beam may be adjusted so that the noise (RIN) value is less than a certain value using the power vs. noise (RIN) characteristic graph as shown in Fig. 5. The light beam power may be adjusted by selecting the beam power.

[0095] After or in parallel with the adjustment of the power of the light beam based on the value of this noise (RIN), the CPU 24 performs the following operation based on the power of the light beam measured by the front monitor 12. The transmittance of the first filter 13 is determined. Specifically, the light beam emitted from the laser diode 11 is formed on the recording surface of the optical disc 50, and does not destroy or erase the recording mark or the recording pin (that is, data reproduction). The transmittance of the first filter 13 is determined so that the power is reduced to a power suitable for the optical disc 50 and condensed on the optical disc 50. For example, when the transmittance of the first filter 13 is set to N% (where 0≤N≤100), the light beam force emitted from the laser diode 11 is a recording mark formed on the recording surface of the optical disc 50. If it is determined that the recording pit is reduced to a certain level of power and focused on the optical disc 50 without destroying or erasing the recording pit, the first filter control is performed under the control of the CPU 24. The unit 27 controls the voltage applied to the first filter 13. Thus, the first filter 13 is maintained in a state where the transmittance is N%. As a result, the light beam emitted from the laser diode 11 is formed on the recording surface of the optical disc 50 !, is a recording mark! /, Or does not destroy the recording pit or erase it to a power level of about Until the optical disc 50 is condensed.

Note that the power of the light beam emitted from the laser diode 11 is reduced to some extent not only when it passes through the first filter 13 but also when it passes through the beam splitter 14 and the objective lens 15. Accordingly, it is preferable to determine the transmittance of the first filter 13 in consideration of the degree of decrease in the noise when transmitting through the beam splitter 14 and the objective lens 15.

As described above, according to the information recording / reproducing apparatus 1 in the example, a suitable recording operation and reproducing operation can be performed. In particular, even when the recording power increases as the recording speed increases, a suitable recording operation and reproducing operation can be performed. Specifically, it is formed on the recording surface of the optical disc 50 while reducing the light beam noise (RIN) while reproducing data that is easily adversely affected by an increase in recording power accompanying an increase in recording speed. The data recorded on the optical disk 50 without destroying or erasing the recording mark or recording pit can be suitably reproduced. Even when data is recorded, data can be suitably recorded on the optical disc 50 regardless of the presence of the first filter 13 or the like.

[0098] In addition, the control can be performed only by controlling the applied voltage to the EC layer 103, the EC layer 113, or the liquid crystal layer 123. The amount of transmission of the light beam emitted from the one diode 11 can be limited. Therefore, it is possible to perform a suitable recording operation and reproducing operation while adopting a simple configuration.

Note that when the first filter 13 is employed, a light beam reflected by the first filter 13 can be generated in addition to the light beam transmitted or absorbed. In this case, if the first filter 13 is installed at an angle with the incident axis of the light beam as a normal line, the light beam reflected on the first filter 13 may stray on the optical axis. There is. Therefore, it is preferable that the first filter 13 is 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 optical axis in the first filter 13.

[0100] If the first filter 13 is placed between the beam splitter 14 and the objective lens 15, absorption or reflection or the like occurs even for the reflected light of the light beam from the optical disk 50. . For this reason, the first filter 13 needs to be installed between the laser diode 11 and the beam splitter 13.

[0101] (2) Second Example

Next, with reference to FIG. 6 and FIG. 7, the description of the information recording / reproducing apparatus in the second example will be continued. FIG. 6 is a block diagram conceptually showing the basic structure of the information recording / reproducing apparatus in the second example. FIG. 7 shows a drive signal output from the laser drive circuit to the laser diode during data recording. FIG. 6 is a waveform diagram illustrating the waveform of the second filter, the transmittance of the second filter, and the waveform of the power of the reflected light received by the photodetector along the time axis

[0102] The same components as those in the information recording / reproducing apparatus 1 in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in FIG. 6, the information recording / reproducing apparatus 2 according to the second embodiment includes an optical pickup 10a, a photodetector amplifier 21, a reproducing circuit 22, a laser noise measuring circuit 23, a CPU 24, and a recording A circuit 25, a laser drive circuit 26, a first filter control circuit 27, a spindle motor 28, a received light power setting circuit 31, a comparator 32, and a second filter control circuit 33 are provided.

[0104] Particularly in the second embodiment, the optical pickup 10a includes the second filter 18 on the optical path of the reflected light from the optical disc 50 of the light beam between the beam splitter 14 and the condenser lens 16. Yes.

The second filter 18 transmits the amount of reflected light of the light beam incident on the second filter 18 under the control of the second filter control circuit 33 (that is, the light incident on the second filter 18). It has a configuration that can change the transmittance of the reflected light of the beam. Normally, in the information recording / reproducing apparatus 2, when attempting to increase the data recording speed for the optical disc 50, the power of the light beam applied to the optical disc 50 per unit time exceeds a predetermined threshold, or the optical disc 50 Since the temperature above is required to be a certain value or more, it is necessary to increase the power of the light beam applied to the optical disc 50. On the other hand, if the power of the light beam is increased when recording data on the optical disc 50, the amount of reflected light received by the photodetector 17 and the light of the recording power when the optical disc 50 is irradiated with a light beam of reproduction power. When the optical disc 50 is irradiated with the beam, the difference in the amount of reflected light received by the photodetector 17 becomes large, and the photodetector 17 may not be able to receive both reflected lights normally. Therefore, in the present embodiment, the amount of reflected light transmitted when the optical disc 50 is irradiated with the recording power light beam is reduced by the second filter 18 to reduce the reflected light power reaching the photodetector 17. Adopt the configuration to let you.

Note that the specific configuration of the second filter 18 is the same as the specific configuration of the first filter 13 described above (see FIGS. 2 to 4). In addition, since the absorbance of the EC material used for the second filter 18 varies depending on the material used, the power of the reflected light during recording and the dynamics of the photo detector 17 must be determined when the second filter 18 is specifically designed. Based on the range, it is necessary to calculate the power of the reflected light transmitted through the second filter 18 and adjust the thickness of the EC layer. For example, in the case of the present embodiment, since it is configured to use light beams with wavelengths of 405 nm, 660 nm, and 780 ηm, reflected light of any wavelength is absorbed during data recording, and is applied to the photodetector 17 during data recording. It is necessary to reduce the power of the reflected light that is received. For this reason, for example, when PB (Prussian Blue) is used as the EC layer, the colorless power also becomes colored blue when 0.2 [V] is applied, and is required at a low voltage by giving an appropriate film thickness. Filter characteristics can be obtained.

The received light power setting circuit 31 is used to detect the light beam to be received by the photodetector 17. Set the power of the reflected light. Specifically, the power within the dynamic range of the photodetector 17 or a fixed value is set as the reflected light power of the light beam to be received by the photodetector 17.

The comparator 32 compares the reflected light power of the light beam set in the received light power setting circuit 31 with the reflected light power of the actual light beam output from the photodetector amplifier 21. The result is output to the second filter control circuit 33.

The second filter control circuit 33 constitutes a specific example of the “second filter control means” of the present invention under the control of the CPU 24, and the reflected light of the light beam received by the photodetector 17. The power change of the second filter 18 is controlled so that the power set by the light receiving power setting circuit 31 is obtained.

As described above, in the information recording / reproducing apparatus 2 including the second filter 18, the second filter control circuit 33 controls the voltage applied to the second filter 18 under the control of the CPU 24. Thus, the light absorption characteristic of the second filter 18 is changed. Specifically, during reproduction of data recorded on the optical disc 50, the second filter control circuit 33 controls the voltage applied to the second filter 18 under the control of the CPU 24 to control the second filter 18. Maintain the maximum amount of reflected light transmitted (ie, transparent). As a result, the power of the reflected light that is reduced in the second filter 18 is minimized. As a result, it is possible to minimize the reduction in the power of the reflected light incident on the photodetector 17 during the reproduction of the data recorded on the optical disc 50, and to secure the RF signal level during the reproduction.

[0111] On the other hand, when data is recorded on the optical disc 50, that is, when the light beam is irradiated with the recording power, the second filter control circuit 33 controls the second filter 18 under the control of the CPU 24. By controlling the applied voltage, the reflected light of a predetermined frequency is absorbed, and the second filter 18 is maintained in a state where the transmittance of the reflected light is lowered. As a result, the reflected light from the optical disk 50 is reduced in power by the second filter 18 and is incident on the photodetector 17, and the reflected light received by the photodetector 17 has the same power as the reproduction power. Will be reduced.

[0112] At this time, the photo-detector 1 at the time of data recording and at the time of data reproduction, respectively. The power of the reflected light received by 7 The second filter 18 is controlled so as to be equal to the power set by the light receiving power setting circuit 31, so that the photo detector 17 at each time of data recording and data reproduction 17 The power of the reflected light received at the same level can be kept within the dynamic range of the photodetector 17.

Accordingly, in accordance with the power of the light beam applied to the recording surface of the optical disc 50, for example, in the state where the recording power light beam is applied to the recording surface of the optical disc 50, the reflected light from the optical disc 50 is reflected. After the power of the second filter 18 is reduced, the photodetector 17 receives the light. For this reason, even if the recording speed of data on the optical disc 50 is increased and the power of the light beam applied to the optical disc 50 is increased, the light is properly reflected by the photodetector 17 without complicating the circuit configuration. Light can be received.

[0114] Since the amount of reflected light transmitted through the second filter 18 can be changed based on the voltage applied from the second filter control circuit 33, the reflected light is reflected at the second filter 18 when data is recorded on the optical disc 50. When the data recorded on the optical disc 50 is reproduced, the amount of reflected light from the optical disc 50 is maximized to secure the RF signal level at the time of data reproduction. It is also possible to ensure an SZN ratio of 50 playback.

[0115] It should be noted that the transmission amount is decreased when the power of the light beam irradiated onto the recording surface of the optical disc 50 becomes strong, and the transmission amount is increased when the power of the light beam becomes weak. Also good. Accordingly, the amount of reflected light transmitted through the second filter 18 is controlled each time data is recorded on and reproduced from the optical disc 50, and the design of the photodetector 17 can be facilitated. That is, even if the dynamic range of the photodetector 17 is narrow, the power of the reflected light can be controlled by the second filter 18, so that the optical beam 50 is irradiated with the recording power. Even in such a state, the power of the reflected light received by the photodetector 17 is suppressed to about the reproduction power, and it is possible to realize reliable light reception.

[0116] Particularly, when data is recorded on the optical disc 50, as shown in FIG. 7, a light beam for forming a mark portion corresponding to a recording mark or a recording pit is irradiated. The second filter 18 when the light beam is irradiated to relatively reduce the amount of transmission through the second filter 18 and form a space portion corresponding to a blank portion between recording marks or recording pits. You may comprise so that the permeation | transmission amount of 18 may be increased relatively.

More specifically, as shown in the upper part of FIG. 7, when data is recorded on the optical disc 50, a multi-pulse drive signal is output from the laser driver circuit 26 to the laser diode 11. . The light beam emitted from the laser diode 11 has a waveform substantially similar to this drive signal, and the pulse portion with a large amplitude is a portion for forming a recording mark or recording pit, and a pulse portion with a small amplitude. No record mark V or record pit is formed!

[0118] In this case, as shown in the middle of FIG. 7, the transmission amount of the reflected light of the light beam in the second filter 18 is relatively decreased corresponding to the mark portion, and is correlated with the space portion. Increase. In other words, the amount of transmission of the reflected light is relatively increased in synchronization with the opposite phase of the drive signal (that is, a portion having a relatively small amplitude and a space portion).

As a result, as shown in the lower part of FIG. 7, the average power of the reflected light of the light beam actually received by the photodetector 17 becomes substantially constant.

When the second filter 18 is employed, a light beam reflected by the second filter 18 can be generated in addition to the light beam that is transmitted or absorbed. In this case, if the second filter 18 is installed at an angle with the incident axis of the reflected light of the light beam as a normal line, the light beam reflected on the second filter 18 strays on the optical axis. there is a possibility. Therefore, the second filter 18 is installed at a predetermined angle Θ with respect to the incident axis of the light beam so that reflected light is not generated on the second filter 18. Prefer U ,.

[0121] If the second filter 18 is installed between the beam splitter 14 and the objective lens 15, the light beam irradiated from the laser diode 11 toward the optical disc 50 is also absorbed or reflected. Will occur. Therefore, the second filter 18 needs to be installed between the beam splitter 14 and the condenser lens 16 or between the beam splitter 14 and the photodetector 17. [0122] Furthermore, in the information recording / reproducing apparatus 2 that is useful in this embodiment, the CPU 24, the laser drive circuit 26, the first filter control circuit 27, the received light power setting circuit 31, the comparator 32, the second filter control circuit 33, etc. Needless to say, these forces may be configured integrally with the optical pickup 10a.

In the above embodiment, the optical disc 50 and the recorder or player related to the optical disc 50 as an example of the information recording device or the information reproducing device have been described as an example of the information recording medium. The present invention is not limited to a player, and can be applied to other high-density recording or various information recording media compatible with a high transfer rate, as well as the recorder or player.

[0124] The present invention is not limited to the above-described embodiments, but can be appropriately modified within the scope of the claims and the entire specification without departing from the gist or concept of the invention which can be read. An optical pickup device, an information recording device, and an information reproducing device are also included in the technical scope of the present invention.

Industrial applicability

An optical pickup device, an information recording device, and an information reproducing device according to the present invention are, for example, an optical pickup device used for recording and reproducing data on an information recording medium such as an optical disc, and information provided with the optical pickup device. It can be used for recording devices and information reproducing devices.

Claims

The scope of the claims

[1] a light source that emits emitted light onto a recording surface of an information recording medium;

A light intensity control means for changing the light intensity of the emitted light;

A first filter disposed on an optical path of the outgoing light and controlling a transmission amount of the outgoing outgoing light;

First filter control means for controlling the first filter so as to control the transmission amount of the emitted light according to the light intensity of the emitted light;

An optical pickup device comprising:

[2] The light intensity control means controls the light intensity of the emitted light so that noise of the emitted light is not more than a predetermined first threshold value.

2. The first filter control unit according to claim 1, wherein the first filter control unit controls the first filter so that a light intensity of the emitted light on the recording surface is equal to or lower than a predetermined second threshold value. Optical pickup device.

[3] The first threshold value is an upper limit value of the range of the noise that does not adversely affect the reproduction of data recorded on the information recording medium. The optical pickup device described in 1.

[4] The second threshold value is an upper limit value of a range of light intensity on the recording surface suitable for reproducing data recorded on the information recording medium. The optical pickup device according to Item.

[5] The first filter control means relatively reduces the transmission amount of the first filter when reproducing the data recorded on the information recording medium, and records the data on the information recording medium. The first filter so that the amount of transmission through the first filter is relatively increased.

2. The optical pickup device according to claim 1, wherein the filter is controlled.

6. The optical pickup according to claim 1, wherein the light intensity control means changes the light intensity of the emitted light in accordance with data recording and reproduction on the information recording medium. apparatus.

[7] The first filter is: A light-absorbing layer whose absorption wavelength varies depending on the value of the applied voltage;

An electrode for applying the voltage to the light absorption layer;

With

2. The optical pick-up device according to claim 1, wherein the first filter control means controls the first filter by changing a value of the voltage applied to the electrode.

[8] The first filter is:

A liquid crystal layer including a liquid crystal element whose molecular arrangement changes according to the value of the applied voltage; an electrode for applying the voltage to the liquid crystal layer;

With

9. The optical pickup device according to claim 1, wherein the first filter is disposed with a predetermined angle with respect to the optical path of the emitted light.

[10] a light receiving means for receiving reflected light from the recording surface;

A second filter disposed on an optical path of the reflected light and controlling an amount of transmitted reflected light that is incident;

Second filter control means for controlling the second filter so as to control the transmission amount of the reflected light according to the light intensity of the reflected light;

The optical pickup device according to claim 1, further comprising:

[11] The second filter control means controls the second filter so that the light intensity of the reflected light incident on the light receiving means falls within a dynamic range of the light receiving means. The optical pickup device according to claim 10.

[12] The range of claim 10, wherein the second filter control means controls the second filter so that the light intensity of the reflected light incident on the light receiving means becomes substantially constant. The optical pickup device described.

[13] The second filter control means may be configured such that the light intensity of the reflected light is relatively strong. The second filter is controlled so that the transmission amount is relatively decreased and the transmission amount is relatively increased when the light intensity of the reflected light becomes relatively weak. The optical pickup device according to claim 10.

[14] When recording the data on the information recording medium, the second filter control means relatively increases the amount of transmitted reflected light corresponding to the space portion of the data, and 11. The optical pickup apparatus according to claim 10, wherein the second filter is controlled so as to relatively reduce the transmission amount of the reflected light corresponding to the mark portion.

[15] The second filter control means, when recording data on the information recording medium, synchronizes with the reflected light in synchronism with the reverse phase of the recording pulse used for emitting the recording output light. 11. The optical pickup device according to claim 10, wherein the second filter is controlled so as to relatively increase or decrease the amount of transmitted light.

[16] The second filter is:

A light-absorbing layer whose absorption wavelength varies depending on the value of the applied voltage;

An electrode for applying the voltage to the light absorption layer;

With

11. The optical pickup device according to claim 10, wherein the second filter control means controls the second filter by changing a value of the voltage applied to the electrode.

[17] The second filter is:

With

18. The optical pickup device according to claim 10, wherein the second filter is disposed with a predetermined angle with respect to the optical path of the reflected light.

[19] a light source for irradiating the recording surface of the information recording medium with emitted light;

Recording means for recording data on the information recording medium;

An information recording apparatus comprising:

[20] a light source for irradiating the recording surface of the information recording medium with emitted light;

Reproducing means for reproducing data recorded on the information recording medium;

An information reproducing apparatus comprising: