Abstract: An optical disc having a power calibration area for calibrating the power of a data recording laser beam. The power calibration area is provided at an inner peripheral part of the disc and has test areas and count areas. The test areas are provided to accomplish trial writing of data, and the count areas are provided to record data representing the use condition of the test areas. Data is recorded on the optical disc, while calibrating the data recording laser beam. The number of the test areas is increased in accordance with an increase in the recording density of the optical disc. The optical disc may be a double-density CD. In this case, the disc has 800 to 1200 test areas. The test areas have the smallest possible size, and the count areas are provided in the smallest possible number. Therefore, the disc can have sufficiently large data regions. Thus, the power of the data recording laser beam can be therefore adjusted many times.

Abstract: Physical addresses of the recording areas provided on an optical disc are represented in a time-axis data format and in a binary data format. The physical address value gradually increases from the inner part of the disc to the outer part of the disc, while the formats remain in one-to-one correspondence over the recording areas. The distance the optical head must move to reach a target recording area can therefore be calculated easily independently of where on the disc the optical head is located, enabling the optical head to quickly access the target recording area.

Abstract: A tornado type air intake and blowing device has an exhaust port communicating with an exhaust duct, an air supply chamber which is provided so as to surround the exhaust port and to which air is supplied through an air supply inlet, and air blowing ports blowing air supplied into the air supply chamber by swirling the air from the outer periphery of the exhaust port diagonally downward, the air blowing ports being provided in a side wall part of the air supply chamber, whereby the exhaust port can be formed in the entire area of the lower opening surface of the air supply chamber, the outside diameter of the air supply chamber is sufficient if it is equal to an outside diameter corresponding to the required opening diameter of the exhaust port and, accordingly, a device body can be formed compact.

Abstract: To enable a plurality of types of optical discs different in recording density from each other and quickly getting “ready” for writing and/or reading data to and/or from each of such optical discs, various controlling conditions requisite for the data writing and reading operations are stored in a memory for both optical discs having first and second recording densities, respectively. For a shorter time up to a “ready” state for data write or read, a controller makes an instant discrimination, based on the pattern of a sync signal “SYNC” included in an ATIP wobble signal supplied from an ATIP decoder, between the optical disc having the first recording density and that having the second recording density, reads, from the memory, controlling conditions corresponding to the result of the disc type discrimination, and sets operating parameters for each component of the optical disc drive.

Abstract: Within a sub-code to be recorded in a recording medium, the physical characteristics of the recording medium are recorded. This enables a recording apparatus or a reading apparatus to easily and correctly determine the physical characteristics of the recording medium by reading the sub-code. The physical characteristic information includes information concerning the material, the disc type, the linear velocity, the track pitch, the moment of inertia, and the size/configuration of the recording medium. It is thus possible to easily and correctly determine the physical characteristics of the disc (or unit area) while maintaining the compatibility with known recording media.

Abstract: An air intake and blowing device, comprising a blowing fan (11) such as a turbo fan capable of blowing air in all directions which is installed inside a main casing (2) provided with an air intake port (5) and an air blowing port (9) enclosing the air intake port (5), the air blowing port (9) being provided with a vortex flow creating member which creates a spiral blowing vortex air flow to form a spirally swirl-blowing air flow, and air surrounded by the blowing air flow being formed in a stable tornado flow and sucked strongly into the air intake port (5).

Abstract: In a recording medium, the physical characteristic information of the recording medium, and more specifically, the configuration (shape and size) and the moment of inertia of the disc, is recorded. This enables a recording apparatus or a reading apparatus to easily and correctly determine the physical characteristics of the disc, and thus to perform suitable settings for the recording or reading operation.

Abstract: Physical addresses of the recording areas provided on an optical disc are represented in the first format that is time-axis data and the second format that is binary data. The physical address value gradually increases from the inner most part toward the outermost part of this disc, while the first format and the second format remains in one-to-one correspondence over the entire recording areas. The distance the optical head must move to reach the target recording area can therefore be calculated easily, no matter where on the disc the optical is located at present. This enables the optical head to make a fast access to the target recording area.

Abstract: Within a sub-code to be recorded in a recording medium, the physical characteristics of the recording medium are recorded. This enables a recording apparatus or a reading apparatus to easily and correctly determine the physical characteristics of the recording medium by reading the sub-code. The physical characteristic information includes information concerning the material, the disc type, the linear velocity, the track pitch, the moment of inertia, and the size/configuration of the recording medium. It is thus possible to easily and correctly determine the physical characteristics of the disc (or unit area) while maintaining the compatibility with known recording media.

Abstract: An optical disc having a power calibration area for calibrating the power of a data recording laser beam. The power calibration area is provided at an inner peripheral part of the disc and has test areas and count areas. The test areas are provided to accomplish trial writing of data, and the count areas are provided to record data representing the use condition of the test areas. Data is recorded on the optical disc, while calibrating the data recording laser beam. The number of the test areas is increased in accordance with an increase in the recording density of the optical disc. The optical disc may be a double-density CD. In this case, the disc has 800 to 1200 test areas. The test areas have the smallest possible size, and the count areas are provided in the smallest possible number. Therefore, the disc can have sufficiently large data regions. Thus, the power of the data recording laser beam can be therefore adjusted many times.

Abstract: To enable a plurality of types of optical discs different in recording density from each other and quickly getting “ready” for writing and/or reading data to and/or from each of such optical discs, various controlling conditions requisite for the data writing and reading operations are stored in a memory for both optical discs having first and second recording densities, respectively. For a shorter time up to a “ready” state for data write or read, a controller makes an instant discrimination, based on the pattern of a sync signal “SYNC” included in an ATIP wobble signal supplied from an ATIP decoder, between the optical disc having the first recording density and that having the second recording density, reads, from the memory, controlling conditions corresponding to the result of the disc type discrimination, and sets operating parameters for each component of the optical disc drive.

Abstract: A low-speed focus servo operation in which an objective lens is moved slowly is performed in a start process that is executed after mounting of an optical recording medium. On the other hand, a high-speed focus search operation in which the objective lens is moved fast is started when focusing is lost in a state that a focus servo operation is being performed. In the high-speed focus search operation, the focus servo characteristic is set to a modified version of a characteristic that is determined by a calibration operation that is performed in the start process.

Abstract: The present invention provides a disc reproduction apparatus capable of correctly and easily read out a bar code data without carrying out a strictly constant angular velocity control. The disc reproduction apparatus according to the present invention includes a measurement block for measuring an edge interval of a bar code signal extracted from reading a bar code data recording area on a disc and a decoder for using the edge interval values measured by this measurement block, so as to decode the bar code data. This decoder identifies each of the edge interval values with a corresponding bar interval according to a distribution of the edge values measured.