Abstract: In an information recording system, information is recorded, through light from a light source, in a recording medium comprising a recording layer which has a phase reversibly changeable between a crystal phase and an amorphous phase. The light source emits, for forming a record mark in the recording layer, multi-pulse light which includes a head heating pulse, a head cooling pulse and following rear heating pulse and rear cooling pulse in the stated order. The head heating pulse includes a front division and a rear division. The difference in light-emission power between the head heating pulse and an immediately following cooling pulse is larger than the difference in light-emission power between another heating pulse and an immediately following cooling pulse.

Abstract: A power control system controls power of light emitted from a light source to a recording medium. The light having a first power is used to erase previous information from the recording medium and the light having a second power is used to record information in the recording medium in a recording operation. The power control system includes a detecting unit for detecting reflected light from the recording medium when the light source emits the light having the first power to erase the information from the recording medium. The detecting unit outputs a reflection signal corresponding to the reflected light. The power control system further has a control unit for controlling the first power of the light emitted from the light source so that a level of the reflection signal output from the detecting means is controlled at a predetermined target level.

Abstract: A trial writing operation is performed on a phase-change optical disc using write and erase light-emitting powers, which together are varied according to predetermined variation ratios respectively. Signals relevant to said trial writing operation are reproduced from said disc. Optimum ones of the write and erase light-emitting powers are determined using the thus-reproduced signals. The predetermined variation ratios for the write and erase light-emitting powers may be the same as each other. Alternatively, the trial writing operation may be performed on a phase-change optical disc using write and erase light-emitting powers which are individually varied according to predetermined variation ratios respectively.

Abstract: Optical information recording medium in which, information of a data format constructed by an ID section and a data section can be recorded and regenerated from both regions of a land portion and a groove portion formed on a disk face. Information such as an address is recorded to the ID section as a format by a PPM recording system when information is recorded to the data section by a PWM recording system. The information recording medium may have a land portion and a groove portion formed in a spiral or concentric shape. A land mark may be formed in a position information section of the land portion and constructed by a pit recorded as position information, and a groove mark may be formed in a position information section of the groove portion. The groove mark may be constructed using an interrupting portion between grooves and recorded as independent position information different from the position information of the land portion.

Abstract: It is an object of the present invention to reduce a data error ratio in the mark edge recording method. In this invention, a corrected value of a record pulse is set by checking the data recording characteristics of an optically recording medium. For this reason, it is possible to adjust a length of a record mark to a specified value as well as to suppress errors such as data errors when data is regenerated.

Abstract: An optical information recording medium in the form of an magneto-optical recording disk with a sector format preformatted in accordance with a mark edge recording method, wherein two types of preformat patterns are provided for an area VFO2 for a PLL, positioned after an area ID1 or an area ID2 indicating a track number or a sector number, with one pattern being selected from the two types of preformat patterns and being preformatted, depending upon whether a prepit preformatted in the area ID1 or the area ID2 is completed within the area ID1 or the area ID2, or is discontinued in the area ID1 or the area ID2.

Abstract: An optical information recording medium in the form of an magneto-optical recording disk with a sector format preformatted in accordance with a mark edge recording method, wherein two types of preformat patterns are provided for an area VFO2 for a PLL, positioned after an area ID1 or an area ID2 indicating a track number or a sector number, with one pattern being selected from the two types of preformat patterns and being preformatted, depending upon whether a prepit preformatted in the area ID1 or the area ID2 is completed within the area ID1 or the area ID2, or is discontinued in the area ID1 or the area ID2.

Abstract: The present invention provides a golf club head made of at least a first and second head components formed integrally with each other. A metallic material of the first head component is different in kind from that of the second head component. At an anti-disjoining device such as a projection, concavity or the like is formed, as a part of the head, on all or a part of an end face of the first head component, which is to join the second head component. Further a metallic material having a melting point 200.degree. C. or more below that of the metallic material of the first head component is cast to the first head component to integrally join the end faces of the first and second head components, thereby forming the second head component.

Abstract: In a method for detecting a defect in a prepit as a sampling object formed on a recording face of an information recording medium in an optical or magnetooptic disk drive unit, an optical or magnetooptic disk is used as the information recording medium and focusing and tracking controls are performed by using a sample servo system at recording and reproducing times of information.

Abstract: A defect detection circuit for optical pick up device having a record medium on which a track is formed which track has a plurality of segments formed in series along the track. The circuit comprises a first detection circuit for detecting a defect of a segment sampled to be detected by comparing difference between a latest data of a refresh signal from the segment and a preceding data of a refresh signal from a preceding segment sampled before the segment to be detected with a first predetermined value. The circuit further comprises a second detection circuit for detecting a defect of the segment to be detected by comparing the latest data with a second predetermined value and a discrimination circuit for discriminating whether the segment is defective or not.