摘要:
An optical disk apparatus having an aberration correcting unit for correcting aberrations generated on the recording surface of an optical disk based on received correcting signals, a servo signal generating unit for generating servo signals based on the reflection lights from the optical disk and predefined parameters, and a birefringence detecting unit that detects the degrees of birefringent portions on the recording surface based on received the servo signals and generates the correcting signals for correcting aberrations according to the detected degrees of the birefringent portions and outputs the correcting signals.
摘要:
In disc discrimination operation of aberration correcting device including: light sources corresponding to n types (n is natural number, ≧2) of discs; and liquid crystal element having plurality of phase variation region (PVR) for correcting spherical aberration (CSA), total sum of maximum value (Max) among absolute values of variations from initial drive voltages (DVs) of applied DVs to DVs for CSA of first light beam in predetermined order for each of PVRs, and Max among absolute values of variations from DVs for CSA of k-th light beam to DVs for that of (k+1)th light beam, voltages being applied in predetermined order for each of PVRs when k (k is natural number that satisfies n−1≧k≧1) is changed from 1 to n−1, is minimum value among total sums determined in the same manner for every order of emitting light from light sources.
摘要:
An optical disk apparatus having an aberration correcting unit for correcting aberrations generated on the recording surface of an optical disk based on received correcting signals, a servo signal generating unit for generating servo signals based on the reflection lights from the optical disk and predefined parameters, and a birefringence detecting unit that detects the degrees of birefringent portions on the recording surface based on received the servo signals and generates the correcting signals for correcting aberrations according to the detected degrees of the birefringent portions and outputs the correcting signals.
摘要:
A control portion of aberration correcting unit includes: a potential calculating block that determines a potential to be applied to each of the divided electrodes of the first transparent electrode and the second transparent electrode; a change quantity calculating block that determines a potential change quantity that is a difference between the determined potential and a potential that is already applied with respect to each of the divided electrodes of the first transparent electrode and the second transparent electrode, and a potential changing block changes the potentials to be applied to the divided electrodes of the first transparent electrode and the second transparent electrode sequentially to the potentials determined by the potential calculating block based on the potential change quantity.
摘要:
A drive controller for electrode group A obtains a disc type, a current layer, and a temperature of the liquid crystal element, and based on contents of the information, it obtains drive voltage values to be applied to the electrodes of the group of electrodes A from the set value table. When the drive voltages to be applied to the group of electrodes A are determined, the drive controller for electrode group A finishes the process, and the process flow goes to a process performed by the drive controller for electrode group B. The drive controller for electrode group B performs initialization of segment numbers. Then, it determines how a phase correction quantity of an electrode Am has changed along with an increase of a radius of the liquid crystal element by using graphs and data, so as to determine the drive voltages to be applied to the group of electrodes B by different calculating methods for different areas in which the electrode Am is disposed.
摘要:
An optical disc apparatus includes a spherical aberration correction element for correcting spherical aberration and a preadjustment unit for obtaining setting of a spherical aberration correction element for correcting spherical aberration appropriately in a case where a focus position of a light beam emitted from a light source is adjusted on each of recording layers of an optical recording medium every time when the optical recording medium is loaded to the apparatus.
摘要:
A liquid crystal element for correcting wave aberration included in an optical disc apparatus, is controlled by a liquid crystal element control unit which has a memory portion that stores information about a variation with time of orientation direction of liquid crystal in the case where a voltage is applied to the liquid crystal, with respect to at least one type of voltage value. The liquid crystal element control unit has a drive voltage deciding portion that obtains time period after a predetermined drive voltage is applied to the liquid crystal element until a reproduced signal obtained by processing an electric signal converted by the light detecting unit becomes optimal, and decides a drive voltage to be applied to the liquid crystal element based on the obtained time period, the information stored in the memory portion, and the predetermined drive voltage.
摘要:
A liquid crystal element control portion of an optical disc apparatus includes a memory for storing first information concerning a relationship between a drive voltage to be applied to a liquid crystal element when an optimal reproduced signal is obtained and ambient temperature of the liquid crystal element and second information concerning a relationship between a response time characteristic of the liquid crystal element and temperature, a drive voltage obtaining portion for measuring a response time of the liquid crystal element at a predetermined timing and obtaining a drive voltage to be applied to the liquid crystal element in which an influence of temperature variation is corrected based on the obtained response time and the first and the second information, and a liquid crystal element driving circuit for driving the liquid crystal element at the drive voltage obtained by the drive voltage obtaining portion.
摘要:
An aberration correction apparatus comprising a liquid crystal device which includes a first electrode layer that is formed with regions divided concentrically, a second electrode layer that is formed with regions divided concentrically, and a liquid crystal that is sandwiched in between the first electrode layer and the second electrode layer, and which transmits an incident light beam therethrough, an objective lens which condenses the light beam transmitted through the liquid crystal device, and a liquid-crystal-device drive circuit which drives the liquid crystal device, wherein the liquid-crystal-device drive circuit impresses a potential which belongs to a predetermined region included in a liquid crystal characteristic that is a relationship between potentials impressed on the respective electrode layers sandwiching in the liquid crystal therebetween and a phase change magnitude of the light beam transmitted through the liquid crystal, on the concentric regions formed in the first electrode layer, and it impresses a potential which belongs to a region included in the liquid crystal characteristic and exhibiting a smaller phase change magnitude per unit drive voltage than in the predetermined region, on the concentric regions formed in the second electrode layer, whereby an aberration of the light beam is corrected.
摘要:
An aberration correction apparatus comprising a liquid crystal device which includes a first electrode layer that is formed with regions divided concentrically, a second electrode layer that is formed with regions divided concentrically, and a liquid crystal that is sandwiched in between the first electrode layer and the second electrode layer, and which transmits an incident light beam therethrough, an objective lens which condenses the light beam transmitted through the liquid crystal device, and a liquid-crystal-device drive circuit which drives the liquid crystal device, wherein the liquid-crystal-device drive circuit impresses a potential which belongs to a predetermined region included in a liquid crystal characteristic that is a relationship between potentials impressed on the respective electrode layers sandwiching in the liquid crystal therebetween and a phase change magnitude of the light beam transmitted through the liquid crystal, on the concentric regions formed in the first electrode layer, and it impresses a potential which belongs to a region included in the liquid crystal characteristic and exhibiting a smaller phase change magnitude per unit drive voltage than in the predetermined region, on the concentric regions formed in the second electrode layer, whereby an aberration of the light beam is corrected.