Optical disc apparatus and method for adjusting the same

Abstract

An adjusting method includes a preparing step for obtaining an applied voltage value and a phase difference in a liquid crystal element in the case where an optimal reproduced signal is obtained for each of a plurality of types of optical recording media by using a reference optical disc apparatus, and for generating and storing predetermined reference data, and an adjusting step for obtaining a voltage value for adjusting characteristic variation of liquid crystal for all the plurality of types of optical recording media by obtaining a first voltage value to be applied to the liquid crystal element in the case where an optimal reproduced signal is obtained for the optical disc apparatus to be adjusted when one type of optical recording medium is regarded as an adjustment optical recording medium among the plurality of types of optical recording media, and by calculating a second voltage value to be applied to the liquid crystal element in which characteristic variation of the liquid crystal is adjusted from the reference data and the first voltage value for each of the plurality of types of optical recording media except the adjustment optical recording medium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram to show a structure of an optical disc apparatus according to one embodiment of the present invention.

FIG. 2 is a schematic diagram of an optical system of an optical pickup device included in the optical disc apparatus according to the present embodiment.

FIGS. 3A and 3B are explanatory diagrams for explaining a structure of a liquid crystal element included in the optical pickup device; FIG. 3A is a cross sectional view, and FIG. 3B is a plan view.

FIG. 4 is a graph to show the spherical aberration and a pattern of a phase difference to be generated by the liquid crystal element for correcting the same.

FIGS. 5A and 5B are explanatory diagrams for explaining a concept of adjusting characteristic variation of the liquid crystal among devices according to the present invention; FIG. 5A is a graph concerning a reference optical disc apparatus, and

FIG. 5B is a graph concerning an optical disc apparatus to be adjusted.

FIG. 6 is a diagram to show a procedure of adjusting method of the optical disc apparatus for adjusting characteristic variation of liquid crystal.

Claims

1. An adjusting method of an optical disc apparatus for adjusting characteristic variation in liquid crystal among optical pick up devices for the optical disc apparatus that can perform reading and writing or perform only reading of a plurality of types of optical recording media and is equipped with a liquid crystal element disposed in the optical system of the optical pickup, the liquid crystal element including liquid crystal and two transparent electrodes sandwiching the liquid crystal, the method comprising: a preparing step for performing a measurement by using an optical pickup having the same optical system as the optical pickup of the optical disc apparatus to be adjusted so as to obtain a reference voltage value that is a voltage value to be applied to the transparent electrode in the case where an optimal reproduced signal is obtained for each of the plurality of types of optical recording media and a reference phase difference that is a phase difference generated in the liquid crystal element when the reference voltage value is applied, and for creating and storing predetermined data concerning the reference voltage value and the reference phase difference as reference data; andan adjusting step for obtaining an adjustment voltage value for adjusting characteristic variation of the liquid crystal for all the plurality of types of optical recording media by selecting one type of optical recording medium among the plurality of types of optical recording media as an adjustment optical recording medium, by obtaining a first voltage value that is applied to the transparent electrode in the case where the optimal reproduced signal is obtained for the optical disc apparatus to be adjusted by using a predetermined optical recording medium for the adjustment optical recording medium, and by calculating a second voltage value to be applied to the transparent electrode in which characteristic variation of the liquid crystal is adjusted from the reference data and the first voltage value for each of the plurality of types of optical recording media except the adjustment optical recording medium.

2. The adjusting method of an optical disc apparatus according to claim 1, wherein at least one of the transparent electrodes is divided into a plurality of concentric areas, and the adjusting step includes a first step for obtaining the first voltage value to be applied to each of the areas for the optical disc apparatus to be adjusted by using the predetermined optical recording medium,a second step for calculating characteristic of the liquid crystal that is determined as a ratio of a difference between the first voltage values in two predetermined areas to a difference between reference phase differences in the two predetermined areas among the first voltage values of the areas obtained in the first step,a third step for calculating the second voltage value for each of the plurality of types of optical recording media except the adjustment optical recording medium by using the characteristic of the liquid crystal obtained in the second step and the reference data, anda fourth step for storing the first and the second voltage values obtained in the first and the third steps as the adjustment voltage value in a storage portion provided to the inside of the optical disc apparatus to be adjusted.

3. The adjusting method of an optical disc apparatus according to claim 2, wherein the two predetermined areas includes an area in which the first voltage value becomes a maximum value and an area in which the first voltage value becomes a minimum value.

4. An adjusting method of an optical disc apparatus for adjusting characteristic variation in liquid crystal among optical pick up devices for the optical disc apparatus that can perform reading and writing or perform only reading of a plurality of types of optical recording media and is equipped with a liquid crystal element disposed in the optical system of an optical pickup, the liquid crystal element including liquid crystal and two transparent electrodes sandwiching the liquid crystal, at least one of the transparent electrodes being divided into a plurality of concentric areas, the method comprising: a preparing step for performing a measurement by using an optical pickup having the same optical system as the optical pickup of the optical disc apparatus to be adjusted so as to obtain a reference voltage value that is a voltage value to be applied to each of the areas of the transparent electrode in the case where an optimal reproduced signal is obtained for each of the plurality of types of optical recording media and a reference phase difference that is a phase difference generated in each of the areas when the reference voltage value is applied, and for creating and storing predetermined data concerning the reference voltage value and the reference phase difference as reference data; andan adjusting step including a first step for selecting one type of optical recording medium among the plurality of types of optical recording media as an adjustment optical recording medium, and for obtaining a first voltage value to be applied to each of the areas in the case where an optimal reproduced signal is obtained for the optical disc apparatus to be adjusted by using the predetermined optical recording medium for the adjustment optical recording medium, a second step for calculating characteristic of the liquid crystal that is determined as a ratio of a difference between a maximum value and a minimum value of the first voltage value to a difference between the reference phase differences in the area where the first voltage becomes a maximum value and the area where the first voltage becomes a minimum value, a third step for calculating a second voltage value to be applied to the transparent electrode in which characteristic variation of the liquid crystal is adjusted for each of the plurality of types of optical recording media except the adjustment optical recording medium by using characteristic of the liquid crystal obtained in the second step and the reference data, and a fourth step for storing the first and the second voltage values obtained in the first and the third steps as the adjustment voltage value for adjusting characteristic variation of the liquid crystal in a storage portion provided to the inside of the optical disc apparatus to be adjusted.

5. An optical disc apparatus that is adjusted by the adjusting method of an optical disc apparatus according to claim 1.