Abstract: A method for monitoring an optical disk drive performance quality by determining a laser diode quality indicator for a laser diode arranged in an optical disk drive for scanning an optical disk, includes measuring an actual value of a parameter associated with a laser diode characteristic, obtaining a reference value of the parameter, comparing the actual value with the reference value for obtaining a comparison result, and determining the laser diode quality indicator from the comparison result. The laser diode quality indicator can at least take a warning level signaling a precursor for a defective state of the optical disk drive and an error level signaling a defective state of the optical disk drive. The laser diode characteristic may be a light-current or a voltage-current relationship.

Abstract: An optical scanning device is adapted for scanning a record carrier having an outer face. The optical scanning device comprises a radiation source for generating a radiation beam, and an objective system having an exit face arranged for evanescent coupling of the radiation beam between the exit face and the outer face and for converging the radiation beam to a focus. A gap servo maintains a distance between the exit face and the outer face at a predetermined gap height. The optical scanning device includes a control unit for setting the predetermined gap height at at least two different values.

Abstract: Recordable DVD+R and DVD+R/W optical discs with two (or more) information layers are developed to double the data storage capacity and video recording time. A method and device are proposed to make dual layer DVD disc recordings compliant with the dual layer DVD-ROM standard Recording the data in a DVD-ROM compliant way on the dual layer DVD+R or DVD+R/W disc is obtained by shifting the middle zone area towards the inner radius of a disc in such a way that the data zones of both layers are filled up with data.

Abstract: An optical disk drive and a method for scanning an optical disk that includes a substantially circular track with a scanning velocity is provided. A servo control signal (SCS) is determined based on a servo error signal (SES). A first performance indicator (IND1) of the servo actuator is determined from at least one of the SES and SCS. IND1 is compared against a first pre-determined threshold (ITHR1), determining a first servo margin (MAR1). The scanning velocity is set in dependence on at least MAR1. In particular, scanning velocity is reduced when the first performance indicator exceeds the first pre-determined threshold. Additionally or alternatively, a bandwidth of control of the servo actuator can be adjusted in dependence on at least one of a second servo margin, determined from at least one of SES and SCS, and a third servo margin, associated with a mark quality determined from a central aperture signal.

Abstract: An optical disk drive for determining a disk characteristic of an optical disk comprising an information layer comprising a substantially circular track is described. The optical disk drive has an optical pickup unit arranged to generate a beam, direct the beam to the optical disk for forming an incident beam, sense a reflected beam produced by the optical disk with a sensor upon receiving the incident beam with the sensor, produce a sensor output signal from sensing the reflected beam; a disk receiving device arranged to receive the optical disk; a motor arranged to provide a transition of the disk receiving device from a first mode to a second mode in at least one transition phase; and a controller arranged to receive the sensor output signal during at least one part of the at least one transition phase and perform at least part of determining the disk characteristic from at least the sensor output signal received during the at least one part of the at least one transition phase.

Abstract: The optical scanning device [10] is arranged for scanning a record carrier [1]. The record carrier has an outer face [7]. The scanning device comprises a radiation source [11] for generating a radiation beam [12] and an objective system [25] having an exit face [26] arranged for evanescent coupling of the radiation beam between the exit face and the outer face and for converging the radiation beam to a focus [27]. A tilt measuring system [67, 77] provides a tilt signal [87; 88] representing a tilt angle between the objective system and the record carrier. A control unit [95] determines a distance signal representing a distance between the exit face and the focus from the tilt signal.

Abstract: A method of reducing power dissipation in a variable-gain photo-detector circuit is described. The variable-gain photo-detector circuit has an output to output a main spot signal and at least one side spot signal. The main spot (M) and the side spot (Si or S2) are formed by separating a light beam into a main beam and at least one side beam and focusing the main beam on the main spot (M) and the side beam on at least one side spot (Si or S2) on an optical record carrier The method processes the main spot signal with a first averaging circuit having a first cut-off frequency. The side spot signal is processed with a second averaging circuit having a second cut-off frequency. The second cut-off frequency is lower than the first cut-off frequency. The above technique reduces power dissipation in the variable-gain photo-detector circuit and is useful for all optical devices.

Abstract: A method for estimating maximum available write power of an optical storage drive includes generating a beam of laser light having a power level, measuring a first parameter of the laser light source and a second parameter of the beam of laser light, and using the measured parameters to estimate the maximum available write power.

Abstract: An optical disk drive and a method for determining a disk type are described. The optical disk drive may be arranged to receive a radial error signal while an incident beam is focused onto the optical disk and before tracking the track, to analyze the radial error signal for detecting whether a wobble signal is present, indicating whether the track is wobbled, and to derive a disk type from the wobble signal, if present. The optical disk drive may additionally or alternatively be arranged to receive a central aperture signal while the incident beam is focused onto the optical disk and before tracking a track including a sequence of embossed pits, to analyze the signal amplitude of the central aperture signal, and to determine the disk type from at least a first variation of the signal amplitude of the central aperture signal as a function of time.

Abstract: In a tracking control method for use in an optical disk drive to read/write an optical disk, an open-loop tracking control operation of the optical disk drive is first performed according to an input tracking error signal and a predetermined periodical offset to generate a dynamic offset. Afterwards, a closed-loop tracking control operation of the optical disk drive is performed according to the input tracking error signal calibrated with the dynamic offset.

Abstract: The present invention relates to a method of selecting a range of gain values (2000) of a gain-bandwidth limited photo-detector circuit (45) for reading data from a record carrier (104). The method comprises: a) finding a first read power by setting a maximum allowable gain value (gma?), the first read power being a minimum read power value at which data is readable from the rotating record carrier at a first speed; and b) finding a second read power and a second gain value, by increasing the first read power value and decreasing the maximum allowable gain value. The second read power being the minimum read power value at which data is readable from the rotating record carrier at a second speed. The method is useful for all kinds of photo-detector circuits in optimizing gain values and achieving optimum performance with the optimum number of gain values.

Abstract: An optical disk drive for determining a disk characteristic of an optical disk comprising an information layer comprising a substantially circular track is described. The optical disk drive has an optical pickup unit arranged to generate a beam, direct the beam to the optical disk for forming an incident beam, sense a reflected beam produced by the optical disk with a sensor upon receiving the incident beam with the sensor, produce a sensor output signal from sensing the reflected beam; a disk receiving device arranged to receive the optical disk; a motor arranged to provide a transition of the disk receiving device from a first mode to a second mode in at least one transition phase; and a controller arranged to receive the sensor output signal during at least one part of the at least one transition phase and perform at least part of determining the disk characteristic from at least the sensor output signal received during the at least one part of the at least one transition phase.

Abstract: Recordable DVD+R and DVD+R/W optical discs with two (or more) information layers are developed to double the data storage capacity and video recording time. A method and device are proposed to make dual layer DVD disc recordings compliant with the dual layer DVD-ROM standard Recording the data in a DVD-ROM compliant way on the dual layer DVD+R or DVD+R/W disc is obtained by shifting the middle zone area towards the inner radius of a disc in such a way that the data zones of both layers are filled up with data.

Abstract: An optical scanning device is adapted for scanning a record carrier having an outer face. The optical scanning device comprises a radiation source for generating a radiation beam, and an objective system having an exit face arranged for evanescent coupling of the radiation beam between the exit face and the outer face and for converging the radiation beam to a focus. A gap servo maintains a distance between the exit face and the outer face at a predetermined gap height. The optical scanning device includes a control unit for setting the predetermined gap height at at least two different values.

Abstract: An optical disk drive and a method for scanning an optical disk that includes a substantially circular track with a scanning velocity is provided. A servo control signal (SCS) is determined based on a servo error signal (SES). A first performance indicator (IND1) of the servo actuator is determined from at least one of the SES and SCS. IND1 is compared against a first pre-determined threshold (ITHR1), determining a first servo margin (MAR1). The scanning velocity is set in dependence on at least MAR1. In particular, scanning velocity is reduced when the first performance indicator exceeds the first pre-determined threshold. Additionally or alternatively, a bandwidth of control of the servo actuator can be adjusted in dependence on at least one of a second servo margin, determined from at least one of SES and SCS, and a third servo margin, associated with a mark quality determined from a central aperture signal.

Abstract: A method of determining a maximum allowable read power for a drive-record carrier combination is described. The method finds a forward-sense setpoint value to control a light power control loop, by reading data from the record carrier at which degradation of the data occurs. This technique is useful for all optical storage devices such as CD, DVD and Blu-ray players and recorders.

Abstract: The optical scanning device [10] is arranged for scanning a record carrier [1]. The record carrier has an outer face [7]. The scanning device comprises a radiation source [11] for generating a radiation beam [12] and an objective system [25] having an exit face [26] arranged for evanescent coupling of the radiation beam between the exit face and the outer face and for converging the radiation beam to a focus [27]. A tilt measuring system [67, 77] provides a tilt signal [87; 88] representing a tilt angle between the objective system and the record carrier. A control unit [95] determines a distance signal representing a distance between the exit face and the focus from the tilt signal.

Abstract: The invention relates to a method for monitoring an optical disk drive performance quality by determining a laser diode quality indicator for a laser diode arranged in an optical disk drive for scanning an optical disk. The determining includes measuring (1000) an actual value (ITHACT) of a parameter (ITH) associated with a laser diode characteristic, obtaining (2000) a reference value (ITHR) of the parameter, comparing (3000) the actual value with the reference value for obtaining a comparison result (ICOM), and determining (4000) the laser diode quality indicator (Qual) from the comparison result. The laser diode quality indicator can at least take a warning level signaling a precursor for a defective state of the optical disk drive and an error level signaling a defective state of the optical disk drive. The laser diode characteristic can e.g. be a light-current relationship or a voltage-current relationship. The parameter can be associated with e.g.

Abstract: A method of reducing power dissipation in a variable-gain photo-detector circuit is described. The variable-gain photo-detector circuit has an output to output a main spot signal and at least one side spot signal. The main spot (M) and the side spot (Si or S2) are formed by separating a light beam into a main beam and at least one side beam and focusing the main beam on the main spot (M) and the side beam on at least one side spot (Si or S2) on an optical record carrier The method processes the main spot signal with a first averaging circuit having a first cut-off frequency. The side spot signal is processed with a second averaging circuit having a second cut-off frequency. The second cut-off frequency is lower than the first cut-off frequency. The above technique reduces power dissipation in the variable-gain photo-detector circuit and is useful for all optical devices.

Abstract: The invention makes use of the air-polycarbonate interface of an optical disk as an accurate reflection reference. The air-polycarbonate interface can be used both during production of an optical disk or during normal operation of an optical disk drive. The air-polycarbonate reflection measurement can be used in a number of applications, including the process of identifying an optical disk during normal operation, detecting contamination of the optical disk during use, and testing of an optical disk during manufacture.