| 摘要 |
PROBLEM TO BE SOLVED: To prevent lowering of the productivity and increasing in size of the structure by providing the optical head device capable of changing the transmission scattering type liquid crystal element, where the inner surfaces of opposed substrates are formed with electrodes capable of changing the voltage applying state on a central part and a peripheral part independently respectively so as to make the low light transmission state of only the central part or the peripheral part turning into the super resolution element state or the nonsuper resolution element state. SOLUTION: A seal material 13 and a transmission scattering type liquid crystal layer are held between the electrodes 11 and 12 provided on the two transparent substrates 10 of glass independently in the central part and the peripheral part respectively to be opposed to each other, so as to constitute a liquid crystal element. A metal oxide film such as ITO, etc., is used for these transparent electrodes 11 and 12, and the transparent substrates 10 are provided with reflection preventing films on the surface opposite to the electrodes 11 and 12, and at the use of the DVD or the CD, a voltage is applied only upon the electrodes 12 or 11. As a result, the liquid crystal element becomes the low light transmission state in the central part or the peripheral part to function as the super resolution element or nonsuper resolution element, and reflected return light from a pit part is incident upon a detector. Consequently, aperture control can be performed by one element, and hence the device is miniaturized and the productivity is enhanced. |
