Abstract: A method controls the access times of an optical disc end discs of the same. The method includes the following steps. First, an optical disc drive obtains the addresses of a life flag and a medium key block (MKB) by reading a private flag of an optical disc. The life flag and the MKB are used to control the access times of the optical disc. After confirming the addresses of the life flag and the MKB, the optical disc drive obtains an optical power signal to determine the power that should be used to read the MKB. When the optical disc drive uses the appropriate reading power to access the MKB, the recognizable number of access times in the 4KB data is reduced, and the medium key signal is extracted to be confirmed if it is recognizable to restate the main data.

Abstract: This specification disclosed a method of determining the disc type for a disc burner to determine the type of an unfinalized disc. By checking the special bit data in the first and second tracks, the discs can be classified into different types. This avoids the trouble of manually keeping track of the type of each disc.

Abstract: A watermark embedding method based on DCT subband image characters is disclosed. An original image is converted into a frequency image using a discrete cosine transformation. The watermark information is then embedded into a specific embedding block in each macro-block of the frequency image. The method has the following advantages: (1) the image embedded by watermark is resistant from distortion and damages from compressions; (2) the watermark image can be extracted without employing the original image; and (3) the quality of the image embedded with the watermark image can remain intact.

Abstract: A disc burner and its control method applicable to high speed disc burner, to solve disc burning failure problem due to burning speed exceeding encoding speed. A buffer is inserted to store the encoded data in groups, and these data groups are used in sequence for disc burning purpose. Therefore, the waiting time of the writing laser is spread out and does not exceed the threshold waiting time, and there is no disc burning failure problem.

Abstract: The present invention relates to an objective lens optical part for an optical pickup device and a focusing method using the same. The focusing method at least includes the steps of providing a first optical member and a second optical member corresponding to the first optical member, dividing a light source into a first optical beam and a second optical beam via the first optical member and the second optical member, and applying a random dithering mechanism to the second optical beam, such that respective pickup optical spot and tracking optical spot can be achieved, wherein the pickup spot picks up more data and the tracking optical spot facilitates tracking operation, thus improving tracking and accuracy of the picked up data.

Abstract: This specification disclosed a method of determining the disc type for a disc burner to determine the type of an unfinalized disc. By checking the special bit data in the first and second tracks, the discs can be classified into different types. This avoids the trouble of manually keeping track of the type of each disc.

Abstract: A disc burner and its control method applicable to high speed disc burner, to solve disc burning failure problem due to burning speed exceeding encoding speed. A buffer is inserted to store the encoded data in groups, and these data groups are used in sequence for disc burning purpose. Therefore, the waiting time of the writing laser is spread out and does not exceed the threshold waiting time, and there is no disc burning failure problem.

Abstract: The specification disclosed a method that controls the access times of an optical disc and discs of the same. The method includes the following steps. First, an optical disc drive obtains the addresses of a life flag and a medium key block (MKB) by reading a private flag of an optical disc. The life flag and the MKB are used to control the access times of the optical disc. After confirming the addresses of the life flag and the MKB, the optical disc drive obtains an optical power signal to determine the power that should be used to read the MKB. When the optical disc drive uses the appropriate reading power to access the MKB, the recognizable number of access times in the MKB data is reduced, and the medium key signal is extracted to be confirmed if it is recognizable to restore the main data.

Abstract: A watermark embedding method based on DCT subband image characters is disclosed. An original image is converted into a frequency image using a discrete cosine transformation. The watermark information is then embedded into a specific embedding block in each macro-block of the frequency image. The method has the following advantages: (1) the image embedded by watermark is resistant from distortion and damages from compressions; (2) the watermark image can be extracted without employing the original image; and (3) the quality of the image embedded with the watermark image can remain intact.

Abstract: A rewritable DVD-RAM disc. By changing the location or dimension of the lead-out area of the DVD-RAM disc, the data area of the disc can be enlarged. The enlarged area of the disc can be flexibly applied to the user area, the main spare area, or the backup spare area.

Abstract: A method is proposed for managing defect areas on an erasable optical disc in a dynamic manner. By this method, a main spare area including a plurality of logical blocks is used to provide substitution logic blocks for any bad logical blocks in the user read/write area; and when all the logical blocks in the main spare area are used up, a supplementary spare area is defined from a continuous unused storage area in the user read/write area; and further, when all the logical blocks in this supplementary spare area are used up, an additional supplementary spare area is defined from another continuous unused storage area in the user read/write area; and so forth. The method allows the use of a comprehensive set of commands and data message for the communication between the file system and the optical drive when performing this management method.

Abstract: This invention relates to a DVD reading-writing pickup head employing multiple wavelengths for data access on an optical record medium. With the configuration of the pickup head of the present invention, the number of the used optical elements is minimized. The pickup head of the present invention includes a cemented birefringent prism, a plurality of objective lenses, quarter-wavelength plates and laser sources and a photo detector. The cemented birefringent prism is used to refract the laser beams generated by the laser sources into an incident branch and split the laser beams and a reflected branch reflected from the optical record medium.

Abstract: This invention concerns a reading-writing pickup head for data access on optical record media. The pickup head of the present invention includes a birefringent prism and a quarter-wave plate where the birefringent prism is made of double-refraction material with different refraction indices on different polarizations, and it is used to split the incident and reflection beams of the pickup head. According to the present invention, the prism and the polarized beam splitter of a pickup head of the related art are replaced with the birefringent prism. Consequently, the number of optical elements of the pickup head according to the present invention is reduced.

Abstract: A compact optical pickup head which doesn't utilize a holographic optical element is disclosed. A birefringent prism and a quarter-wave plate are disposed in the optical path of the compact pickup head. The birefringent prism is consisted of two crystals made from a birefringent material, and having their optical axes perpendicular to each other. Therefore, the laser source beam will not be refracted when passing through the birefringent prism or will be refracted to a direction differing from the returning beam), while the returning beam is refracted by the birefringent prism to the photo detector. The power of laser ray is fully utilized to increase the reliability of signal transformation. A higher optical signal can be obtained, and the interference of returning beam to the source beam is also be prevented.

Abstract: A double focal-point magneto-optic pick-up head is provided. This magneto-optic pick-up head reads data from an optical disc by using a diffraction grating to diffract a laser beam into two diffracted beams of equal intensity which are focused on the optical disc at two focal points. One focal point is pinpointed on one groove portion of the optical disc, and the other focal point is pinpointed on one neighboring land portion of the same. This allows the two reflected beams to have a difference in propagation length equal to twice the depth of the land portion. The reflected beams are subsequently diffracted again by the diffraction grating into four beams, two of which are directed to interfere with each other to thereby produce an interference beam representative of a read signal from the optical disc. Since the depth is fixed by manufacture, the difference in propagation length between the two reflected beams from the two focal points on the optical disc can always be maintained at a constant.

Abstract: A single-lens optical pick-up head has a laser diode, a beam splitter, a collimator, a polarizing light converter, a polarization controller, a polarizing beam splitter, a first quarter-wavelength plate, a mirror, a second quarter-wavelength plate, a convex mirror, an objective lens and a photodetector, for use in accessing DVD and CD discs by switching its optical property between two states.

Abstract: A digital video disc optical pick-up head system has a laser light source, a beam splitter, a collimating len, a polarization changer, a deflecting mirror, an optical crystal assembly, an objective len and a photosensor assembly. These optical components together constitute an optical pick-up head system that generates only a single focus at any one time. When an alternative focus is required, polarized light of an alternative polarization is used for generating a detectable opto-electrical signal for the photosensor.

Abstract: A beam shaper device for an optical read/write head on an optical disc drive is provided. This beam shaper device is particularly useful for shaping a laser beam originally emitted with an elliptical cross section, into having a substantially circular cross section. The beam shaper device includes only one prism and one plane mirror. The shape of the prism and the orientation of the plane mirror are specifically devised in such a way as to allow the output beam shaper device to have a circular cross section and to have its propagation axis orthogonal to that of the input laser beam.

Abstract: A miniature optical head for optical disk drive units is disclosed. The head assembly comprises a polarization light-splitter means having a block-shaped body. A laser light source generates a laser light beam at a predetermined wavelength and illuminating into the block body of the polarization light-splitter means. A first quarter-wavelength light plate means arranged at a side surface of the block-shaped body of the polarizing light-splitter means is placed opposite the laser light source. A reflective diffraction grating arranged further external to the first quarter-wavelength light plate means is used for reflectively diffracting the laser light beam. A second quarter-wavelength light plate means is arranged to a surface of the block-shaped polarizing light-splitter means in a plane perpendicular to the first quarter-wavelength light plate means. A holographic optical element is arranged on a side surface of the block-shaped body opposite the second quarter-wavelength light plate means.

Abstract: A coaxial master-slave lens system is provided. The coaxial master-slave lens system can be either fixed-focus type or zoom type, and can be equipped to any camera equipment. In such a coaxial master-slave lens system, a slave lens is provided as an additional attachment to the master lens. The slave lens is provided with a center hollowed portion for accommodating the master lens in such a manner that the slave optical axis is in coincidence with the master optical axis; the slave front lens plane is in coincidence with the master front lens plane; the slave rear lens plane is in coincidence with the master rear lens plane; the slave front focus point is in coincidence with the master front focus point; and the slave rear focus point is in coincidence with the master rear focus point.