Abstract: An imaging unit captures an image of an entire recording surface of an optical recording medium. An image storing unit stores the image captured as one image of a recording surface image. A track-information calculating unit calculates a virtual center point and an actual track pitch of the optical recording medium. An image-analysis-path generating unit matches a center of an image analysis path with the virtual center point of the recording surface image stored. An image analyzing unit performs an image analysis of the pits sequentially from an innermost periphery according to the image analysis path, and converts the pit arrangement information of the track into a digital signal, and stores the digital signal converted.

Abstract: An apparatus for carrying out a fine servo control and a rough servo control with respect to the rotation of a motor for rotating a recording medium in accordance with information recorded on the recording medium. A fine servo signal is generated on the basis of a reproduction clock, filtered by a first filtering device, and used for the fine servo control. A rough servo signal is generated on the basis of a frame synchronizing signal, filtered by a second filtering device, and used for the rough servo control. The first filtering device has a first frequency band, and the second filtering device has a second frequency band. The upper limit of the second frequency band is lower than that of the first frequency band.

Abstract: An auto-loading system of disk playback apparatus includes a door open/close detecting device for detecting that a door is being closed when a disk is being ejected, and loads the disk into the disk playback apparatus by the detection signal therefrom. According to another aspect, the apparatus generates an alarm immediately when detection is made thereby that the door is being closed when the disk is being ejected.

Abstract: A gain controlling apparatus is provided with: an adjusting device (6, 7, 8) for adjusting a gain of a generation signal, which is generated on the basis of a light reception signal obtained by receiving a reflection light of a light beam from an information recording medium (1); and a detecting device (21, 14, 16) for detecting whether or not the generation signal is generated and outputting a detection signal when the generation signal is generated. The gain controlling apparatus is also provided with a controlling device (18) for controlling the adjusting device to increase the gain by a predetermined value set in advance when the detection signal is not outputted by the detecting device.

Abstract: An automatic gain control device includes: reading unit for reading information signal from a recording medium; servo loop including servo control unit for controlling position of the reading unit with respect to the recording medium; mixing unit for mixing a disturbance signal into the servo loop; gain control unit detecting gain of the servo loop in accordance with level of the disturbance signal and varying the gain of the servo loop; and level detecting unit for discriminating whether level of the information signal read by the reading unit is higher than a predetermined level or not, wherein the mixing unit mixes the disturbance signal into the servo loop when the level of the information signal is higher than the predetermined level.

Abstract: An automatic gain control device includes: reading unit for reading information signal from a recording medium; servo loop including servo control unit for controlling position of the reading unit with respect to the recording medium; mixing unit for mixing a disturbance signal into the servo loop; gain control unit detecting gain of the servo loop in accordance with level of the disturbance signal and varying the gain of the servo loop; and level detecting unit for discriminating whether level of the information signal read by the reading unit is higher than a predetermined level or not, wherein the mixing unit mixes the disturbance signal into the servo loop when the level of the information signal is higher than the predetermined level.

Abstract: A cutting insert is disclosed which includes a polygonal plate-like insert body defined by a front face, a rear face and a plurality of side faces lying between the front face and the rear face. The insert body has at least one main cutting edge defined by the intersection of the front face with one of the side faces and at least one nose portion intersecting the at least one main cutting edge and defined by one of the corners of the front face. The front face has an inclined surface extending immediately from the nose portion and sloping toward the rear face in a direction away from the nose portion.