Patent
High-frequency superposition automatic output controller for laser
TLDR
In this paper, the authors proposed a method to prevent the increase of the transient output power of an oscillation circuit, and to set a luminous output at a set value automatically by providing a means in which the rise time when high-frequency currents are superposed to laser driving currents is made simultaneous with or later than the response time of an automatic output control loop.Abstract:
PURPOSE: To prevent the increase of the transient output power of an oscillation circuit, and to set a luminous output at a set value automatically by providing a means in which the rise time when high-frequcncy currents are superposed to laser driving currents is made simultaneous with or later than the response time of an automatic output control loop. CONSTITUTION:An optical disk 2 for an optical disk device 1 is turned and driven by a spindle motor arranged in the vertical direction, an optical head 3 is disposed oppositely to one surface of the disk 2, and the disk 2 is irradiated with light beams. A laser diode 5 is housed in the head 3, and the diode 5 is controlled by output currents from an APC circuit 7 for controlling power. The diode 5 is supplied with high-frequency currents from an oscillation circuit 8 for high-frequency superposition. A pin photodiode for monitor is sealed into the diode 5, and luminous a output in case of the operation of the circuit 8 is set automatically to set-value power by the currents of the diode.read more
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Patent
Method and device for automatic frequency control of semiconductor lasers
TL;DR: In this article, a method for automatic frequency control of semiconductor kasers is presented, in which the signal emitted from a laser (1) is sent to an optical resonator (6) whose resonance frequency is modulated by a ramp signal, and the signal outgoing from the resonator is converted into an electrical signal, the derivative of the electrical signal is calculated, the zero crossing of the derivative is detected, the ramp signal is sampled in corresponding with such a zero crossing, the sample thus obtained is algebraically summed to a reference signal depenent on the nominal laser
Patent
Optical disk device
TL;DR: In this paper, the authors propose to set a recording light quantity state under a condition fitting in a recording mode when a mode is switched to the recording mode even by performing high frequency superimposing by starting automatic light quantity control after a time when monitor output to detect the light emitting quantity of a laser diode arrives at a constant value when the mode is migrated from the recording to a reproducing mode.
Patent
Light modulation method for optical disk drive device
TL;DR: In this article, a recovery is promptly executed for a reading error of a track address in a modified constant angular velocity format, when a defective reading operation of the track address occurs, a clock frequency of the zone corresponding to each detecting position is selected due to the detection of the head by a head position sensor or the movement of a head to a home position at which a detection signal of a home positioning sensor is obtained, and the reading operation is retried.
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Optical disk apparatus for detecting error readings of a track address in MCAV format
TL;DR: In this article, a recovery is promptly executed for a reading error of a track address in a modified constant angular velocity format, when a defective reading operation of the track address occurs, a clock frequency of the zone corresponding to each detecting position is selected due to the detection of the head by a head position sensor or the movement of a head to a home position at which a detection signal of a home positioning sensor is obtained, and the reading operation is retried.
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Patent
Laser drive circuit
TL;DR: In this paper, the authors propose to make light modulation degree uniform and to reduce noise by permitting a sequence controller to set the output of a target value generator to a level (a) to cause a holder to hold a current signal, then setting the output output of the target value generators to asymptotically increase or decrease the output amplitude of a variable amplitude generator.