JP2007317293A - Optical pickup device and optical information device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent destruction of existing data when linear velocity of recording and playing back is switched in one and the same optical disk without making focusing servo unstable by an optical beam transmission adjusting means for adjusting optical power of the optical beam emitted from a light source. <P>SOLUTION: The optical beam transmission adjusting means 100 is constituted of a beam splitter 101, a liquid crystal element 102, and an optical beam transmission adjustment control circuit 103. The liquid crystal element 102 rotates a polarization direction of the optical beam made incident according to allied voltage. The optical beam transmission adjustment control circuit 103 outputs voltage while continuously varying a voltage value when output voltage is switched. Also, the circuit 103 attenuates a transmission rate continuously during recording or playing back operation for one and the same optical disk before linear velocity of the optical disk for an optical pickup device is switched from high linear velocity to low linear velocity in one and the same radius position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical pickup device and an optical information device including the optical pickup device. More specifically, the present invention relates to an optical pickup device and an optical information device that emit a short-wavelength semiconductor laser such as a blue-emitting semiconductor laser using a GaN-based semiconductor.

  A digital versatile disc (DVD) is an information recording medium that can record digital data at a recording density about six times that of a compact disc (CD) and can write large-capacity digital data such as movies and music. Is known as a so-called optical disk.

  In recent years, since the amount of information to be recorded has increased, an information recording medium having a larger capacity has been demanded.

  In order to increase the capacity of the information recording medium of the optical disc, it is necessary to increase the information recording density. This is generally realized by reducing the spot diameter of the laser beam emitted to the optical disc at the time of data writing and reading. In order to reduce the spot diameter of the light, the wavelength of the laser light can be shortened and the numerical aperture (NA) of the objective lens can be increased. In DVD, a light source with a wavelength of 660 nm and an objective lens with NA of 0.6 are used. Furthermore, for example, by using a blue laser beam having a wavelength of 405 nm and an objective lens having an NA of 0.85, information can be recorded at a recording density five times that of the current DVD.

  In addition to shortening the wavelength of laser light using a blue laser or the like, development of a technique for providing a plurality of recording layers on one optical disk has been advanced in order to further increase the recording density. For example, if it becomes possible to obtain an optical disc having two recording layers, the recording density has one recording layer in combination with the above-described shortening of the laser beam wavelength and the use of an objective lens having a large NA. About 10 times that of DVD.

  However, in an optical disk apparatus using a blue laser as a light source, the margin of optical power for reproduction in the blue laser is extremely small, so that quantum noise of the light source becomes a problem.

  Therefore, various measures have been devised to solve the problem of quantum noise of the light source.

  For example, in the conventional optical disc apparatus shown in Patent Document 1, when the recording layer of the loaded optical disc is one layer, an intensity filter is inserted on the optical axis by rotation, and when there are a plurality of recording layers, a transmission filter is inserted. For example, the quantum noise of the semiconductor laser can be kept low, and high quality reproduction is possible.

  Hereinafter, the optical pickup device will be described with reference to FIGS. 14, 15A, and 15B.

  FIG. 14 is a configuration explanatory view showing a configuration of a conventional optical pickup device. When the GaN-based semiconductor laser light source 41 emitting blue light emits a blue light beam, the light beam is incident on the light beam transmission adjusting element 200. The light beam transmission adjusting element 200 is rotated to a predetermined position depending on whether data is read from the optical disc 50 or data is written to the optical disc 50, and the position of the intensity filter is adjusted. The light beam that has passed through the light beam transmission adjusting element 200 is reflected by the beam splitter 42, converted into parallel light by the collimator lens 43, reflected by the mirror 44, transmitted through the objective lens 45, and condensed on the optical disk 50. The

  At the time of reading data, the condensed light beam is reflected by the recording layer of the optical disc 50, reaches the beam splitter 42 through the reverse path, passes through the beam splitter 42, and enters the photodiode 48 through the multi lens 47. To do. The photodiode 48 is a so-called photodetector, and outputs an electrical signal based on the position and intensity of incident light. Data is reproduced based on the electrical signal.

  On the other hand, when writing data, a light spot is formed on the information layer by the condensed light beam. As a result, the state of the recording layer where the light spot is formed, for example, the crystal state changes according to the data to be written. As a result, data is written on the optical disc 50 as a change in the state of the recording layer.

  FIG. 15A is a perspective view when the light beam passes through the optical filter of the light beam transmission adjusting element 200, and FIG. 15B shows the light beam not passing through the optical filter of the light beam transmission adjusting element 200. FIG. The light beam travels in the direction indicated by the arrow.

  The light beam transmission adjustment element 200 includes a first transmission element 201, a second transmission element 202, a rotation shaft 203, a support unit 204, and a rotation drive unit 205. The first transmissive element 201 is coated with an optical filter 201a that reduces the transmittance, and attenuates the optical power of the transmitted light beam. On the other hand, the second transmission element 202 is not coated with an optical filter, and transmits the light beam with the optical power of the light beam substantially maintained. The support means 204 rotatably supports the first transmissive element 201 and the second transmissive element 202 around the rotation axis 203. The rotating shaft 203 is parallel to the first transmissive element 201 and the second transmissive element 202. The rotation driving unit 205 rotates the first transmission element 201 and the second transmission element 202 around the rotation axis 203.

  The light beam transmission adjusting element 200 uses the rotation driving means 205 to rotate around the rotation axis 203 so that the light beam passes through the first transmission element 201 (FIG. 15A). It is possible to switch whether the light passes through the two transmissive elements 202 (FIG. 15B). That is, it is possible to switch whether the light beam passes through the optical filter 201a or not. The light power when the light beam is transmitted through the optical filter 201a can be suppressed lower than when the light beam is not transmitted.

Patent Document 2 discloses a technique for solving the problem of quantum noise of a light source by using an optical coupling efficiency variable element for each recording surface of recording and reproduction or different types of optical disks and multilayer optical disks. It is disclosed by reference 6.
JP 2006-40432 A JP 2002-260272 A JP 2003-157666 A JP 2003-196880 A JP 2004-220744 A Japanese Patent Application Laid-Open No. 2004-272962

  However, according to the configuration in which the first transmission element 201 and the second transmission element 202 of the light beam transmission adjustment element 200 are switched by rotation, the optical power output in a state where the quantum noise of the semiconductor laser is kept low with a simple configuration. While this can be reduced, the servo signal becomes unstable when the optical filter is switched, that is, when the light beam transmittance is switched.

  More specifically, the transmittance is switched instantaneously by switching the first transmissive element 201 and the second transmissive element 202 by rotation, and the optical power output as the optical pickup device changes instantaneously. It becomes. Accordingly, the intensity of light reflected by the recording layer of the optical disc 50 and incident on the photodiode 48 changes instantaneously. That is, the sensitivity of the focusing error signal in the focusing servo changes instantaneously, and the focusing servo becomes unstable. As a result, there is a problem that the response of the servo becomes slow and the merchantability of the apparatus is lowered.

  In addition, the linear velocity of the optical disk with respect to the optical pickup device at the same radial position is increased due to various factors that cause the servo to be in an unstable state such as disturbance vibration or a sudden temperature change during the recording or reproducing operation on the same optical disk. When switching from the speed to the low linear speed, the recorded data may be destroyed if the linear speed of the optical disk decreases before the transmittance of the light beam transmission adjusting means decreases.

  The present invention has been made in order to solve the above-described problem. The optical disk transmission adjusting means for adjusting the optical power of the light beam emitted from the light source does not destabilize the focusing servo, and the same optical disk. Thus, an object of the present invention is to provide an optical pickup apparatus and an information processing apparatus that do not destroy existing data when the linear velocity of recording / reproducing is switched.

  The present invention provides an optical pickup device having the following configuration in order to solve the above technical problem.

According to the first aspect of the present invention, a light source that emits a light beam having a predetermined optical power;
A light beam transmission adjusting means for adjusting a transmission amount of the light beam;
Condensing means for condensing the light beam transmitted through the light beam transmission adjusting means on an information recording medium,
In the optical pickup device that selectively outputs an arbitrary optical power by changing the transmittance by the light beam transmission adjusting means,
Provided is an optical pickup device characterized by continuously changing the transmittance of the light beam transmission adjusting means while keeping the light power of the light beam emitted from the light source constant.

  According to a second aspect of the present invention, the light beam transmission adjusting means includes a liquid crystal element, a beam splitter element, and a light beam transmission adjustment control circuit for continuously changing the transmittance. An optical pickup device according to a first aspect is provided.

  According to a third aspect of the present invention, there is provided the optical pickup device according to the first or second aspect, wherein the light beam transmission adjustment control circuit starts recording after increasing the transmittance during reproduction. To do.

  According to a fourth aspect of the present invention, the light beam transmission adjustment control circuit continuously changes the transmittance according to a layer to be recorded or reproduced on an information recording medium having a plurality of recording layers. An optical pickup device according to one or two aspects is provided.

  According to a fifth aspect of the present invention, the information recording medium has a disk shape, and the light beam transmission adjustment control circuit has a plurality of recording areas having different linear velocities for recording or reproduction. The optical pickup device according to the first or second aspect is characterized in that the transmittance is continuously changed in accordance with switching of a recording area to be recorded or reproduced.

  According to a sixth aspect of the present invention, the information recording medium has a disk shape, and the light beam transmission adjustment control circuit adjusts the transmittance according to a change in linear velocity during a recording or reproducing operation with respect to the same information recording medium. The optical pickup device according to the first or second aspect is characterized by being changed.

  According to a seventh aspect of the present invention, the information recording medium has a disc shape, and the light beam transmission adjustment control circuit has a linear velocity during a recording or reproducing operation with respect to the same radial position of the same information recording medium. The optical pickup device according to the first or second aspect is characterized in that the transmittance is changed according to the change.

  According to an eighth aspect of the present invention, the information recording medium has a disk shape, and the light beam transmission adjustment control circuit has a linear velocity during a recording or reproducing operation with respect to the same radial position of the same information recording medium. Provided is an optical pickup device according to the first or second aspect, wherein the transmittance is continuously changed according to switching.

  According to a ninth aspect of the present invention, the information recording medium has a disk shape, and the light beam transmission adjustment control circuit has a high linear velocity during a recording or reproducing operation with respect to the same information recording medium. The optical pickup device according to any one of the fifth to eighth aspects is characterized in that the transmittance is lowered before switching from low to low linear velocity.

According to a tenth aspect of the present invention, a light source that emits a light beam having a predetermined optical power;
Condensing means for condensing the light beam emitted from the light source on an information recording medium;
An optical pickup device comprising an aberration correction liquid crystal element of a light spot focused on the information recording medium;
An aberration correction control circuit for controlling the aberration correction liquid crystal element,
The aberration correction control circuit provides an optical information device characterized by continuously changing the aberration correction amount.

  According to an eleventh aspect of the present invention, the aberration correction liquid crystal element corrects spherical aberration, and the aberration correction control circuit corrects spherical aberration according to a recording or reproducing layer for an information recording medium having a plurality of recording layers. An optical information device according to a tenth aspect is provided in which the amount is continuously changed.

  According to a twelfth aspect of the present invention, the aberration-correcting liquid crystal element corrects coma aberration, the information recording medium is disk-shaped, and the aberration correction control time is recorded on the disk-shaped information recording medium. Alternatively, the optical information apparatus according to the tenth aspect is provided, wherein the coma aberration amount to be corrected is continuously changed according to the radial position to be reproduced.

According to a thirteenth aspect of the present invention, any one of the optical pickup devices according to the first to ninth aspects;
A motor for rotating the information recording medium;
Provided is an optical information device comprising an electric circuit that receives a signal obtained from the optical pickup device and controls and drives the motor and the optical pickup device based on the signal.

According to a fourteenth aspect of the present invention, a light source that emits a light beam having a predetermined optical power;
A light beam transmission adjusting means for adjusting a transmission amount of the light beam, comprising a liquid crystal element and a beam splitter element;
Condensing means for condensing the light beam transmitted through the light beam transmission adjusting means on an information recording medium,
An optical pickup device that selectively outputs an arbitrary optical power by changing the transmittance by the light beam transmission adjusting means;
A light beam transmission adjustment control circuit for changing the transmittance according to a change in linear velocity during a recording or reproducing operation on the same information recording medium;
A motor for rotating the information recording medium;
An optical information device comprising an electric circuit that receives a signal obtained from the optical pickup device and controls and drives the motor and the optical pickup device based on the signal is provided.

According to the fifteenth aspect of the present invention, a light source that emits a light beam having a predetermined optical power;
A light beam transmission adjusting means for adjusting a transmission amount of the light beam, comprising a liquid crystal element and a beam splitter element;
Condensing means for condensing the light beam transmitted through the light beam transmission adjusting means on an information recording medium,
An optical pickup device that selectively outputs an arbitrary optical power by changing the transmittance by the light beam transmission adjusting means;
A light beam transmission adjustment control circuit that changes the transmittance according to a change in linear velocity during a recording or reproducing operation with respect to the same radial position of the same information recording medium;
A motor for rotating the information recording medium;
An optical information device comprising an electric circuit that receives a signal obtained from the optical pickup device and controls and drives the motor and the optical pickup device based on the signal is provided.

According to the sixteenth aspect of the present invention, a light source that emits a light beam having a predetermined optical power;
A light beam transmission adjusting means for adjusting a transmission amount of the light beam, comprising a liquid crystal element and a beam splitter element;
Condensing means for condensing the light beam transmitted through the light beam transmission adjusting means on an information recording medium,
An optical pickup device that selectively outputs an arbitrary optical power by changing the transmittance by the light beam transmission adjusting means;
A light beam transmission adjustment control circuit for continuously changing the transmittance in accordance with the switching of the linear velocity during the recording or reproducing operation with respect to the same radial position of the same information recording medium;
A motor for rotating the information recording medium;
An optical information apparatus comprising: an electric circuit that receives a signal obtained from the optical pickup device and controls and drives the motor and the optical pickup device based on the signal.

According to a seventeenth aspect of the present invention, a light source that emits a light beam having a predetermined optical power;
A light beam transmission adjusting means for adjusting a transmission amount of the light beam, comprising a liquid crystal element and a beam splitter element;
Condensing means for condensing the light beam transmitted through the light beam transmission adjusting means on an information recording medium,
An optical pickup device that selectively outputs an arbitrary optical power by changing the transmittance by the light beam transmission adjusting means;
A light beam transmission adjustment control circuit that reduces the transmittance before switching from a high linear velocity to a low linear velocity during a recording or reproducing operation on the same information recording medium;
A motor for rotating the information recording medium;
An optical information device comprising an electric circuit that receives a signal obtained from the optical pickup device and controls and drives the motor and the optical pickup device based on the signal is provided.

According to an eighteenth aspect of the present invention, any one of the optical information devices according to the tenth to seventeenth aspects;
An input device or input terminal for inputting information;
An arithmetic device that performs an operation based on information input from the input device or information reproduced from the optical information device;
Provided is a computer having an output device or an output terminal for displaying or outputting information input from the input device, information reproduced from the optical information device, and a result calculated by the arithmetic device.

According to a nineteenth aspect of the present invention, any one of the optical information devices according to the tenth to seventeenth aspects;
There is provided an optical disc player having an information-to-image decoder for converting an information signal obtained from the optical information device into an image.

According to a twentieth aspect of the present invention, any one of the optical information devices according to the tenth to seventeenth aspects;
A car navigation system having an information-to-image decoder for converting an information signal obtained from the optical information device into an image is provided.

According to a twenty-first aspect of the present invention, any one of the optical information devices according to the tenth to seventeenth aspects;
An optical disk recorder having an image-to-information encoder for converting image information into information to be recorded by the optical information device is provided.

According to a twenty-second aspect of the present invention, any one of the optical information devices according to the tenth to seventeenth aspects;
An optical disc server having an input / output terminal for transmitting / receiving information to / from the outside is provided.

  According to the first aspect of the present invention, since the transmittance is continuously changed by the light beam transmission adjusting means, the optical power output as the optical pickup device does not change instantaneously, and the focusing error signal in the focusing servo is not changed. Since the sensitivity does not change instantaneously, the focusing servo does not become unstable. As a result, a stable servo response can be obtained, and the merchantability of the apparatus is improved.

  According to the second aspect of the present invention, by supplying an arbitrary voltage to the liquid crystal element by the light beam transmission adjustment control circuit, it is possible to easily change the transmittance continuously to an arbitrary transmittance.

  According to the third aspect of the present invention, it is possible to shift from the reproducing operation to the recording operation while maintaining a stable servo state.

  According to the fourth aspect of the present invention, the optical power and transmittance of the light source are optimally selected by an arbitrary recording layer of the information recording medium having a plurality of recording layers, so that the light source of the light source is kept to a minimum while keeping the light power of the light source to a minimum. Quantum noise can be kept low. Further, by continuously changing the transmittance, the interlayer jump from any recording layer to another recording layer can be performed while maintaining a stable servo state.

  The optical pickup device of the fourth aspect can be suitably used for an information recording medium having two, four, and eight recording layers.

  According to the fifth aspect of the present invention, for an information recording medium having a plurality of recording areas with different linear velocities for recording or reproduction, by optimally selecting the light power and transmittance of the light source depending on the arbitrary recording area, The quantum noise of the light source can be kept low while keeping the light power of the light source to a minimum. Further, by continuously changing the transmittance, random access from an arbitrary recording area to another recording area can be performed while maintaining a stable servo state.

  According to the sixth to eighth aspects of the present invention, the servo state is stable when the linear velocity of the information recording medium with respect to the optical pickup device is changed at the same radial position during the recording or reproducing operation with respect to the same information recording medium. The linear velocity can be changed while maintaining.

  According to the ninth aspect of the present invention, a change in the linear velocity of the information recording medium relative to the optical pickup device at the same radial position during the recording or reproducing operation with respect to the same information recording medium, particularly from a high linear velocity to a low linear velocity. Existing data can be prevented from being destroyed by continuously attenuating the transmittance before switching to.

  According to the tenth aspect of the present invention, since the aberration correction amount is continuously changed by the aberration correction means, the aberration of the light beam condensed on the recording surface of the information recording medium does not change instantaneously, The focusing servo does not become unstable. As a result, a stable servo response can be obtained, and the merchantability of the apparatus is improved.

  According to the eleventh aspect of the present invention, an interlayer from any recording layer to another recording layer is continuously changed to an optimum spherical aberration correction amount by any recording layer of the information recording medium having a plurality of recording layers. Jumps can be performed while maintaining a stable servo state.

  According to the twelfth aspect of the present invention, from an arbitrary radial position to another radial position by continuously changing the optimal coma aberration correction amount according to the radial position to be recorded or reproduced on the disk-shaped information recording medium. Random access can be performed while maintaining a stable servo state.

  The optical pickup device according to the first to twelfth aspects of the present invention can be suitably used as an optical information device.

  According to the fourteenth to sixteenth aspects of the present invention, the servo state is stable when the linear velocity of the information recording medium with respect to the optical pickup device is changed at the same radial position during the recording or reproducing operation with respect to the same information recording medium. The linear velocity can be changed while maintaining.

  According to the seventeenth aspect of the present invention, a change in the linear velocity of the information recording medium relative to the optical pickup device at the same radial position during the recording or reproducing operation with respect to the same information recording medium, particularly from a high linear velocity to a low linear velocity. Existing data can be prevented from being destroyed by continuously attenuating the transmittance before switching to.

  The optical information apparatus according to the tenth to seventeenth aspects can be suitably used for various apparatuses such as a computer, an optical disk player, a car navigation system, an optical disk recorder, and an optical disk server.

  Hereinafter, an optical pickup device according to a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory diagram of the configuration of the optical pickup device according to the first embodiment, and FIG. 2 shows the relationship between the voltage applied to the liquid crystal element of the optical pickup device according to the first embodiment and the transmittance of the light beam transmission adjusting means. FIG. 3A is a timing chart for explaining changes in the output voltage of the light beam transmission adjustment control circuit and the transmittance of the light beam transmission adjustment means according to the first embodiment, and FIG. It is a timing chart for demonstrating the change of the transmittance | permeability of the light beam permeation | transmission adjustment means when the linear velocity of the optical disk by 1st embodiment changes.

  In FIG. 1, an optical pickup device 11 includes a light source 1, a light beam transmission adjusting unit 100, a beam splitter 2, a collimator lens 3, a mirror 4, an objective lens 5, an actuator coil 6, a multi lens 7, And a photodiode 8.

  The optical pickup device 11 operates by being incorporated in an optical information device including a turntable 362, a motor 364, a rotation control circuit 10, a signal processing circuit 12, and a servo circuit 13.

  The light source 1 is a GaN-based semiconductor laser that emits blue light. The light source 1 also emits coherent light for reading and writing data to the recording layer of the optical disc 14.

  The light beam transmission adjusting means 100 is an optical means for changing the light power by changing the light transmittance and keeping the quantum noise of the light beam emitted from the light source 1 low.

  Here, a detailed configuration of the light beam transmission adjusting unit 100 will be described. The light beam transmission adjusting unit 100 includes a beam splitter 101, a liquid crystal element 102, and a light beam transmission adjustment control circuit 103. The liquid crystal element 102 rotates the polarization direction of the incident light beam according to the applied voltage. Since the light is split into light transmitted through the beam splitter 101 and light reflected by the rotation angle in the polarization direction, the transmittance can be adjusted. The relationship between the voltage applied to the liquid crystal element 102 and the light transmittance that passes through the beam splitter 101 is expressed, for example, in FIG.

  When the output voltage is switched, the light beam transmission adjustment control circuit 103 continuously outputs the voltage value. For example, when the transmittance of the light beam transmission adjusting unit 100 is changed from T1 to T2 shown in FIG. 2, the light beam transmission adjustment control circuit 103 continuously changes the output voltage from V1 to V2 as shown in FIG. Output while changing. As a result, the transmittance of the light beam transmission adjusting unit 100 continuously changes from T1 to T2 based on the characteristics shown in FIG.

  First, the reproducing operation of the optical pickup device 11 will be described. The light source 1 emits a light beam having a predetermined optical power. At this time, the light beam transmission adjustment control circuit 103 of the light beam transmission adjustment means 100 outputs, for example, a voltage of V1. Therefore, the transmittance of the light beam transmission adjusting means 100 is T1. The light beam transmitted through the light beam transmission adjusting unit 100 is reflected by the beam splitter 2, converted into parallel light by the collimator lens 3, and reflected by the mirror 4. Thereafter, the objective lens 5 focuses the light beam on the recording layer of the optical disk 14. The light beam is reflected with a reflectance corresponding to the state of the recording layer of the optical disk 14. The light beam reflected by the recording layer is again transmitted through the objective lens 5, reflected by the mirror 4, transmitted through the collimator lens 3, transmitted through the multi-lens 7, and collected on the photodiode 8. As a result, the photodiode 8 generates and outputs a light amount signal. Based on the light amount signal, the signal processing circuit 12 generates a reproduction signal indicating the content of the written data, a focus error signal, and the like. Further, an actuator drive signal is supplied from the servo circuit 13 to the actuator coil 6 based on the focus error signal, and focusing servo for the recording layer of the optical disk 14 of the objective lens 5 is performed.

  At this time, the signal amplitude of the reproduction signal generated by the signal processing circuit 12 is attenuated in accordance with the transmittance T1 of the light beam transmission adjusting means, in a state that is sufficiently large and sufficient for the reproduction operation and the quantum noise is sufficiently suppressed. Has been generated.

  Next, the operation when shifting from the reproducing operation to the recording operation will be described. In order to make the intensity of the light beam in the recording layer of the optical disk 14 large enough for the recording operation, the transmittance of the light beam transmission adjusting means 100 is changed from T1 to T2. At this time, since the light beam transmission adjustment control circuit 103 outputs the output voltage while continuously changing from V1 to V2, the transmittance also changes continuously from T1 to T2. Accordingly, the optical power output as the optical pickup device 11 does not change instantaneously, and the sensitivity of the focus error signal obtained by the reflected light from the recording layer of the optical disk 14 does not change instantaneously, so that the focusing servo becomes unstable. There is no. As a result, a stable servo response can be obtained, and the merchantability of the apparatus is improved.

  An operation when the linear velocity for the same optical disk changes will be described. For example, due to various factors that cause the servo to be unstable, such as disturbance vibration, optical disk contamination, and sudden temperature changes during recording or reproducing operations on the same optical disk, the optical disk 14 with respect to the optical pickup device at the same radial position The recording or reproducing operation can be continued by switching the linear velocity from the high linear velocity (S2) to the low linear velocity (S1).

  In particular, the problems in this case are not disclosed in Patent Document 2 to Patent Document 6, and with the configuration of Patent Document 2 to Patent Document 6, the optical disk 14 can be used without reducing the transmittance of the light beam transmission adjusting means 100. Is reduced to a low linear velocity (S1), the energy density on the recording surface of the optical disk 14 is increased, and data already recorded may be destroyed.

  In order to solve the above problem, the light beam transmission adjustment control circuit configured in the first embodiment performs the following operation.

  At this time, as shown in FIG. 3B, first, the light beam transmission adjustment control circuit 103 outputs the output voltage while continuously changing the output voltage from V2 to V1, thereby changing the transmittance of the light beam transmission adjustment means 100. Reduce continuously from T2 to T1. After the transmittance of the light beam transmission adjusting means is reduced and the optical power irradiated onto the optical disk 14 is attenuated, the rotation speed of the optical disk 14 is controlled by the motor 364 by the rotation control circuit 10 so that the linear speed is reduced from the high linear velocity (S2). Switch to speed (S1). Therefore, sufficient reliability can be ensured without destroying already recorded data.

  In the first embodiment, by supplying an arbitrary voltage to the liquid crystal element 102 by the light beam transmission adjustment control circuit 103, it is possible to easily realize a continuous change to an arbitrary transmittance.

  The transmittances T1 and T2 of the light beam transmission adjusting means 100 used here are symbols used for convenience to describe the increase / decrease in the transmittance, and the values are the objects of various pickup apparatus configurations and recording / reproduction targets. It is determined as appropriate depending on the type of optical disk to be used. The same applies to the output voltage 1 and V2 of the light beam transmission adjustment control circuit 103, which is a value determined as appropriate based on the characteristics of the liquid crystal element used. The linear velocities S1 and S2 of the optical disk 14 are the same, but for example, a relationship between standard speed and N-times speed may be used.

  In the first embodiment, the light beam transmission adjustment control circuit 103 continuously changes the output voltage in order to continuously change the transmittance of the light beam transmission adjustment means 100 when shifting from the reproducing operation to the recording operation. However, the same effect can be realized by any operation that changes the intensity of the light beam output from the optical pickup device 11.

  For example, when performing an interlayer jump from an arbitrary recording layer to another recording layer for an optical disc having a plurality of recording layers, by optimally selecting the optical power and transmittance of the light source by the arbitrary recording layer of the optical disc 14, The quantum noise of the light source can be kept low while keeping the light power of the light source to a minimum. Further, by continuously changing the transmittance, the interlayer jump from any recording layer to another recording layer can be performed while maintaining a stable servo state.

  Alternatively, for the optical disc 14 having a plurality of recording areas with different linear velocities to be recorded or reproduced, the light power and transmittance of the light source are optimally selected according to an arbitrary recording area, thereby keeping the light power of the light source to a minimum. In addition, the quantum noise of the light source can be kept low. Further, by continuously changing the transmittance, random access from an arbitrary recording area to another recording area can be performed while maintaining a stable servo state.

  Furthermore, due to various factors that cause the servo to be in an unstable state, such as disturbance vibration, contamination of the optical disk 14 or sudden temperature change during the recording or reproducing operation with respect to the same optical disk 14, the optical pickup device 11 can be detected at the same radial position. When the linear velocity of the optical disk 14 is switched from a high linear velocity to a low linear velocity, it is possible to ensure sufficient reliability without destroying already recorded data.

  In the first embodiment, the liquid crystal element 102 is of a type that rotates the polarization direction, but there is a type that converts the transmitted light beam from linearly polarized light to elliptically polarized light. The effect of can be obtained.

  The same effect can be obtained by using a polarizing filter instead of the beam splitter 101.

  Further, in the state where the applied voltage is not applied, a part of the transmitted light is diffracted, and as a result, the 0th-order light transmittance is lowered. However, as the applied voltage is increased, the diffraction of the transmitted light is decreased and consequently 0 By using a diffractive polarization selective element whose next light transmittance becomes higher, a light beam transmission adjusting means can be constituted by one element, and improvement of the reliability and miniaturization are realized by simplifying the apparatus. Needless to say.

  In the first embodiment, the light beam transmission adjustment control circuit 103 has been described as being mounted on the optical pickup device 11, but the same effect can be obtained even if the optical pickup device 11 is mounted on an optical information device. Obtainable.

  Needless to say, if the light beam transmission adjustment control circuit 103 is configured on an integrated circuit, the apparatus can be downsized.

  Hereinafter, an optical pickup device according to a second embodiment of the present invention will be described with reference to the drawings.

  FIG. 4 is a diagram illustrating the configuration of the optical pickup device according to the second embodiment, FIG. 5 is an explanatory diagram illustrating electrode patterns of a liquid crystal element for correcting spherical aberration of the optical pickup device according to the second embodiment, and FIG. 6 is a diagram illustrating the second embodiment. FIG. 7 is an explanatory diagram showing the relationship between the maximum potential difference applied to the spherical aberration correction liquid crystal element of the optical pickup device and the spherical aberration correction amount of the aberration correction means, and FIG. 7 is an output of the spherical aberration correction control circuit according to the second embodiment. It is a timing chart for demonstrating the change of a voltage and spherical aberration correction amount.

  4 is different from FIG. 1 in that the light beam transmission adjusting unit 100 is replaced with an aberration correcting unit 110. FIG.

  The aberration correction unit 110 is an optical unit that corrects the transmitted light beam so as to cancel the generated spherical aberration by changing the phase of the transmitted light beam in accordance with the generation pattern of the spherical aberration.

  Here, a detailed configuration of the aberration correction unit 110 will be described. The aberration correction unit 110 includes a spherical aberration correction liquid crystal element 112 and an aberration correction control circuit 113. The spherical aberration correcting liquid crystal element 112 is configured by the electrode pattern shown in FIG. 5, and a phase difference in the form of inverting the generated spherical aberration by changing the voltage applied to each region with respect to the transmitted light beam. Give the distribution. As a result, the generated spherical aberration can be corrected so as to cancel. At this time, if the voltage between the maximum voltage and the minimum voltage applied to each electrode region is generated by resistance division, the potential applied from the outside may be three terminals of the reference potential, the maximum potential, and the minimum potential. The relationship between the maximum potential difference from the maximum potential to the minimum potential applied to the spherical aberration correcting liquid crystal element 112 and the spherical aberration correction amount is expressed, for example, in FIG.

  When the aberration correction control circuit 113 switches the maximum potential difference applied to the spherical aberration correcting liquid crystal element 112, that is, the voltage, the aberration correction control circuit 113 outputs the voltage value while continuously changing the voltage value. For example, when the spherical aberration correction amount of the aberration correction unit 110 is changed from R1 to R2 shown in FIG. 6, the aberration correction control circuit 113 outputs the output voltage while continuously changing from V1 to V2 as shown in FIG. . As a result, the spherical aberration correction amount of the aberration correction unit 110 continuously changes from R1 to R2 based on the characteristics of FIG.

  Accordingly, since the spherical aberration correction amount is continuously changed by the aberration correction means 110, the spherical aberration of the light beam condensed on the recording surface of the optical disk 14 does not change instantaneously, and the focusing servo becomes unstable. Never become. As a result, a stable servo response can be obtained, and the merchantability of the apparatus is improved. Further, the optical disk 14 continuously changes to an optimal spherical aberration correction amount by an arbitrary recording layer of the optical disk having a plurality of recording layers, thereby providing a stable servo state in an interlayer jump from any recording layer to another recording layer. It can be done while keeping.

  In the second embodiment, the aberration correction unit is a unit that corrects spherical aberration, but the same effect can be obtained by using this as a unit that corrects coma aberration. This case is realized by replacing the spherical aberration correcting liquid crystal element 112 with a coma aberration correcting liquid crystal element 122 constituted by the electrode pattern shown in FIG. In this case as well, the aberration correction control circuit 113 operates in the same manner, and outputs the voltage while continuously changing the voltage value when switching the maximum potential difference applied to the coma aberration correcting liquid crystal element 122, that is, the voltage. For example, when the coma aberration correction amount of the aberration correction unit 110 is changed from R1 to R2 shown in FIG. 9, the aberration correction control circuit 113 outputs the output voltage while continuously changing from V1 to V2 as shown in FIG. . As a result, the coma aberration correction amount of the aberration correction unit 110 continuously changes from R1 to R2 based on the characteristics shown in FIG. Therefore, the random access from any radial position to another radial position is maintained in a stable servo state by continuously changing the optimum coma aberration correction amount according to the radial position to be recorded on or reproduced from the optical disk 14. It can be carried out.

  The aberration correction amounts R1 and R2 of the aberration correction unit 110 used here are symbols used for convenience to describe the increase / decrease in the aberration correction amount, and the values are the targets of various pickup apparatus configurations and recording / reproduction targets. It is determined as appropriate depending on the type of optical disk to be used. The same applies to the output voltage V1 and V2 of the aberration correction control circuit 113, which is a value that is appropriately determined based on the characteristics of the liquid crystal element used.

  In the second embodiment, the aberration correction control circuit 113 is described as being mounted on the optical pickup device 15, but the same effect can be obtained even when the optical pickup device 15 is mounted on an optical information device. Can do.

  Needless to say, if the aberration correction control circuit 113 is configured on an integrated circuit, the apparatus can be downsized.

  Next, an example of an optical information device using the optical pickup device of FIG. 1 or FIG. 4 will be described. FIG. 11A is a perspective view showing a schematic configuration of an optical information device using the optical pickup device of FIG. 1 or FIG. 11B is a schematic diagram showing a mechanism for driving the optical pickup device in the optical information device of FIG. 11A, and FIG. 11C is a schematic diagram of a drive system of the optical information device of FIG. It is a block diagram which shows a structure.

  The optical information device 350 is mounted so that the optical pickup device 300 can be moved in the tracking direction of the optical disc as shown in FIG. As shown in FIG. 11B, the optical pickup device 300 is supported by two guide rails 310 that extend in the tracking direction of the optical disc, and is parallel to the guide rail 310 on one side. The lead screw 311 provided is connected. The lead screw 311 can be rotated about the axis by the motor 312, and the optical pickup device 300 moves in the tracking direction by the rotation of the lead screw 311.

  In FIG. 11A, FIG. 11B, and FIG. 11C, optical disks 370, 371, and 372 are placed on a turntable 362 and rotated by a motor 364. The optical pickup device 300 shown in FIG. 1 or 4 is coarsely moved to a track where desired information exists on the optical disc.

  The optical pickup device 300 also sends a focus error signal and a tracking error signal to the electric circuit 366 corresponding to the positional relationship with the optical discs 370, 371, 372. In response to this signal, the electric circuit 366 sends a signal for driving the actuator to finely move the objective lenses 326 and 344 to the optical pickup device 300. In response to this signal, the optical pickup device 300 performs focus servo and tracking servo on the optical discs 370, 371, and 372, and the optical pickup device 300 reproduces, records, or erases information.

  Since the optical information apparatus uses the optical pickup apparatus shown in FIG. 1 or 4 as the optical pickup apparatus, the single optical pickup apparatus can handle a plurality of optical disks having different recording densities.

  The optical information device 350 shown in FIG. 11A can be mounted on various devices. Since a computer, an optical disc player, and an optical disc recorder equipped with the optical information device of FIG. 11A can stably record or reproduce different types of optical discs, they can be used in a wide range of applications. FIG. 12 is a schematic diagram showing a configuration of a computer on which the optical information device of FIG.

  12, the optical information device 350 of FIG. 11A, the input device 471 such as a keyboard or mouse or touch panel for inputting information, the information input from the input device 471, the optical information device 350 An arithmetic device 472 such as a central processing unit (CPU) that performs an operation based on the read information and an output device 473 such as a cathode ray tube, a liquid crystal display device, or a printer that displays information such as a result calculated by the arithmetic device. The computer 470 provided is configured.

  Further, the computer 470 may be equipped with a wired or wireless input / output terminal that takes in information to be recorded in the optical information device 350 or outputs information read out by the optical information device 150 to the outside. As a result, information can be exchanged with a network, that is, a plurality of devices such as a computer, a telephone, a TV tuner, and the like, and the plurality of devices can be used as a shared information server (optical disk server). Since different types of optical discs can be stably recorded or reproduced, it has an effect that can be used for a wide range of purposes.

  Further, by providing a changer for taking a plurality of optical discs into and out of the optical information device 350, it is possible to obtain an effect that a large amount of information can be recorded / stored.

  FIG. 13A shows a schematic configuration of an optical disc player equipped with the optical information device shown in FIG. 13 (a), an optical disc player 480 having the optical information device 350 of FIG. 11 (a) and an information-to-image conversion device (for example, a decoder 481) for converting an information signal obtained from the optical information device into an image. Configure. This configuration can also be used as a car navigation system. In addition, a display device 482 such as a liquid crystal monitor may be added.

  FIG. 13B shows a schematic configuration of an optical disc recorder equipped with the optical information device shown in FIG. 13B, an optical disc recorder having the optical information device 350 of FIG. 11A and an image-to-information conversion device (for example, an encoder 492) that converts image information into information to be recorded on the optical disc by the optical information device. Configure. Desirably, by mounting an information-to-image conversion device (decoder 491) for converting an information signal obtained from the optical information device into an image, it is possible to reproduce the already recorded portion. An output device 493 such as a cathode ray tube or a liquid crystal display device for displaying information may be provided.

  In addition, although the output device is illustrated in the apparatus using the optical information device 350 of FIG. 11A described above, there is a product form in which an output terminal is mounted on these devices and the output device is configured separately. Needless to say, this is possible. In addition, although the input device is not shown in each of the above devices, a product form including an input device such as a keyboard, a touch panel, a mouse, and a remote control device is also possible. It is also possible to install.

  The optical pickup device according to the present invention is capable of recording / reproducing with respect to a plurality of types of optical disks having different substrate thicknesses, corresponding wavelengths, recording densities, and the like. Further, an optical information device using this optical pickup device is a CD, Many standard optical disks such as DVD and BD can be handled. Accordingly, the present invention can be applied to various systems that record and reproduce information, such as computers, optical disk players, optical disk recorders, car navigation systems, editing systems, optical disk servers, and AV components.

1 is a configuration explanatory diagram of an optical pickup device according to a first embodiment. FIG. It is explanatory drawing which showed the relationship between the voltage applied to the liquid crystal element of the optical pick-up apparatus by 1st embodiment, and the transmittance | permeability of a light beam transmission adjustment means. (A) is a timing chart for explaining the change of the output voltage of the light beam transmission adjustment control circuit and the transmittance of the light beam transmission adjustment means according to the first embodiment, and (b) is the first embodiment. FIG. 6 is a timing chart for explaining the change in transmittance of the light beam transmission adjusting means when the linear velocity of the optical disk changes due to. FIG. 6 is a configuration explanatory diagram of an optical pickup device according to a second embodiment. It is explanatory drawing which shows the electrode pattern of the liquid crystal element for spherical aberration correction of the optical pick-up apparatus by 2nd embodiment. It is explanatory drawing which showed the relationship between the voltage applied to the liquid crystal element for spherical aberration correction of the optical pick-up apparatus by 2nd embodiment, and the spherical aberration correction amount of an aberration correction means. It is a timing chart for demonstrating the change of the output voltage and spherical aberration correction amount of the spherical aberration correction control circuit by 2nd embodiment. It is explanatory drawing which shows the electrode pattern of the liquid crystal element for a coma aberration correction of the optical pick-up apparatus by 2nd embodiment. It is explanatory drawing which showed the relationship between the voltage applied to the liquid crystal element for a coma aberration correction of the optical pick-up apparatus by 2nd embodiment, and the coma aberration correction amount of an aberration correction means. It is a timing chart for demonstrating the change of the output voltage of the coma aberration correction control circuit by 2nd embodiment, and a coma aberration correction amount. (A) is a perspective view which shows schematic structure of the optical information apparatus using the optical head apparatus of FIG. 1 or FIG. 4, (b) drives an optical head apparatus in the optical information apparatus of FIG. 11 (a). FIG. 12C is a block diagram illustrating a schematic configuration of a drive system of the optical information device in FIG. It is the schematic which shows the structure of the computer carrying the optical information apparatus of Fig.11 (a). (A) is a figure which shows schematic structure of the optical disk player carrying the optical information apparatus shown to Fig.11 (a), (b) is an optical disk recorder carrying the optical information apparatus shown to Fig.11 (a). It is a figure which shows schematic structure. It is a configuration explanatory view showing a configuration of a conventional optical pickup device. (A) is a perspective view when the light beam transmission adjusting means optical filter of the conventional optical pickup device is transmitted, and (b) is a light beam transmission adjusting means optical filter of the conventional optical pickup device when not transmitting FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Beam splitter 3 Collimating lens 4 Mirror 5 Objective lens 6 Actuator coil 7 Multi lens 8 Photodiode 10 Rotation control circuit 11 Optical pick-up apparatus 12 Signal processing circuit 13 Focusing servo circuit 14 Optical disk 100 Light beam transmission adjustment means 101 Beam splitter 102 Liquid crystal element 103 Light beam transmission adjustment control circuit 112 Liquid crystal element for spherical aberration correction 113 Aberration correction control circuit 122 Liquid crystal element for coma aberration correction 362 Turntable 364 Motor

Claims (22)

A light source that emits a light beam having a predetermined optical power;
A light beam transmission adjusting means for adjusting a transmission amount of the light beam;
Condensing means for condensing the light beam transmitted through the light beam transmission adjusting means on an information recording medium,
In the optical pickup device that selectively outputs an arbitrary optical power by changing the transmittance by the light beam transmission adjusting means,
An optical pickup device characterized by continuously changing the transmittance of the light beam transmission adjusting means while keeping the optical power of the light beam emitted from the light source constant.   2. The optical pickup device according to claim 1, wherein the light beam transmission adjusting means includes a liquid crystal element, a beam splitter element, and a light beam transmission adjustment control circuit for continuously changing the transmittance.   3. The optical pickup device according to claim 1, wherein the light beam transmission adjustment control circuit starts recording after increasing the transmittance during reproduction.   3. The optical pickup device according to claim 1, wherein the light beam transmission adjustment control circuit continuously changes the transmittance according to a layer to be recorded or reproduced with respect to an information recording medium having a plurality of recording layers. The information recording medium is disk-shaped,
The light beam transmission adjustment control circuit continuously changes the transmittance according to switching of the recording area to be recorded or reproduced with respect to the disk-shaped information recording medium having a plurality of recording areas having different linear velocities to be recorded or reproduced. The optical pickup device according to claim 1, wherein: The information recording medium is disk-shaped,
3. The optical pickup device according to claim 1, wherein the light beam transmission adjustment control circuit changes the transmittance according to a change in linear velocity during a recording or reproducing operation on the same information recording medium. The information recording medium is disk-shaped,
3. The optical pickup according to claim 1, wherein the light beam transmission adjustment control circuit changes the transmittance according to a change in linear velocity during a recording or reproducing operation with respect to the same radial position of the same information recording medium. apparatus. The information recording medium is disk-shaped,
3. The light beam transmission adjustment control circuit continuously changes the transmittance according to switching of the linear velocity during recording or reproducing operation with respect to the same radial position of the same information recording medium. Optical pickup device. The information recording medium is disk-shaped,
The light beam transmission adjustment control circuit reduces the transmittance before switching from a high linear velocity to a low linear velocity during a recording or reproducing operation on the same information recording medium. Item 9. The optical pickup device according to any one of Items 5 to 8. A light source that emits a light beam having a predetermined optical power;
Condensing means for condensing the light beam emitted from the light source on an information recording medium;
An optical pickup device comprising an aberration correction liquid crystal element of a light spot focused on the information recording medium;
An aberration correction control circuit for controlling the aberration correction liquid crystal element,
The aberration correction control circuit continuously changes the aberration correction amount. The aberration correction liquid crystal element corrects spherical aberration,
11. The optical information apparatus according to claim 10, wherein the aberration correction control circuit continuously changes a spherical aberration amount to be corrected according to a layer to be recorded or reproduced with respect to an information recording medium having a plurality of recording layers. The aberration correction liquid crystal element corrects coma aberration,
The information recording medium is disk-shaped,
11. The optical information apparatus according to claim 10, wherein the aberration correction control circuit continuously changes a coma aberration amount to be corrected in accordance with a radial position recorded or reproduced on the disk-shaped information recording medium. An optical pickup device according to any one of claims 1 to 9,
A motor for rotating the information recording medium;
An optical information device comprising: an electric circuit that receives a signal obtained from the optical pickup device and controls and drives the motor and the optical pickup device based on the signal. A light source that emits a light beam having a predetermined optical power;
A light beam transmission adjusting means for adjusting a transmission amount of the light beam, comprising a liquid crystal element and a beam splitter element;
Condensing means for condensing the light beam transmitted through the light beam transmission adjusting means on an information recording medium,
An optical pickup device that selectively outputs an arbitrary optical power by changing the transmittance by the light beam transmission adjusting means;
A light beam transmission adjustment control circuit for changing the transmittance according to a change in linear velocity during a recording or reproducing operation on the same information recording medium;
A motor for rotating the information recording medium;
An optical information device comprising: an electric circuit that receives a signal obtained from the optical pickup device and controls and drives the motor and the optical pickup device based on the signal. A light source that emits a light beam having a predetermined optical power;
A light beam transmission adjusting means for adjusting a transmission amount of the light beam, comprising a liquid crystal element and a beam splitter element;
Condensing means for condensing the light beam transmitted through the light beam transmission adjusting means on an information recording medium,
An optical pickup device that selectively outputs an arbitrary optical power by changing the transmittance by the light beam transmission adjusting means;
A light beam transmission adjustment control circuit that changes the transmittance according to a change in linear velocity during a recording or reproducing operation with respect to the same radial position of the same information recording medium;
A motor for rotating the information recording medium;
An optical information device comprising: an electric circuit that receives a signal obtained from the optical pickup device and controls and drives the motor and the optical pickup device based on the signal. A light source that emits a light beam having a predetermined optical power;
A light beam transmission adjusting means for adjusting a transmission amount of the light beam, comprising a liquid crystal element and a beam splitter element;
Condensing means for condensing the light beam transmitted through the light beam transmission adjusting means on an information recording medium,
An optical pickup device that selectively outputs an arbitrary optical power by changing the transmittance by the light beam transmission adjusting means;
A light beam transmission adjustment control circuit for continuously changing the transmittance in accordance with the switching of the linear velocity during the recording or reproducing operation with respect to the same radial position of the same information recording medium;
A motor for rotating the information recording medium;
An optical information device comprising: an electric circuit that receives a signal obtained from the optical pickup device and controls and drives the motor and the optical pickup device based on the signal. A light source that emits a light beam having a predetermined optical power;
A light beam transmission adjusting means for adjusting a transmission amount of the light beam, comprising a liquid crystal element and a beam splitter element;
Condensing means for condensing the light beam transmitted through the light beam transmission adjusting means on an information recording medium,
An optical pickup device that selectively outputs an arbitrary optical power by changing the transmittance by the light beam transmission adjusting means;
A light beam transmission adjustment control circuit that reduces the transmittance before switching from a high linear velocity to a low linear velocity during a recording or reproducing operation on the same information recording medium;
A motor for rotating the information recording medium;
An optical information device comprising: an electric circuit that receives a signal obtained from the optical pickup device and controls and drives the motor and the optical pickup device based on the signal. An optical information device according to any one of claims 10 to 17,
An input device or input terminal for inputting information;
An arithmetic device that performs an operation based on information input from the input device or information reproduced from the optical information device;
A computer comprising an output device or an output terminal for displaying or outputting information input from the input device, information reproduced from the optical information device, and results calculated by the arithmetic device. An optical information device according to any one of claims 10 to 17,
An optical disc player comprising an information-to-image decoder for converting an information signal obtained from the optical information device into an image. An optical information device according to any one of claims 10 to 17,
A car navigation system comprising an information-to-image decoder for converting an information signal obtained from the optical information device into an image. An optical information device according to any one of claims 10 to 17,
An optical disk recorder comprising an image-to-information encoder for converting image information into information to be recorded by the optical information device. An optical information device according to any one of claims 10 to 17,
An optical disk server equipped with an input / output terminal for transmitting / receiving information to / from the outside.

Images