Abstract: A vehicle includes first and second power supply cords. Positive and negative electrodes of a battery are connected to a first power supply portion and a first ground portion of a first circuit, respectively, by the first power supply cord, and connected to a second power supply portion and a second ground portion of the second circuit, respectively, by the second power supply cord. The first circuit includes a control circuit configured to measure voltages of the second power supply portion as a first voltage and as a second voltage with reference to a potential of the first ground portion and a potential of the second ground portion, respectively. In a case in which the first and second voltages have a predetermined relationship, power supplied from the second power supply cord to the second circuit is set to be a predetermined value or less.

Abstract: A vehicle includes first and second power supply cords. Positive and negative electrodes of a battery are connected to a first power supply portion and a first ground portion of a first circuit, respectively, by the first power supply cord, and connected to a second power supply portion and a second ground portion of the second circuit, respectively, by the second power supply cord. The first circuit includes a control circuit configured to measure voltages of the second power supply portion as a first voltage and as a second voltage with reference to a potential of the first ground portion and a potential of the second ground portion, respectively. In a case in which the first and second voltages have a predetermined relationship, power supplied from the second power supply cord to the second circuit is set to be a predetermined value or less.

Abstract: A load short-circuit detection method is a load short-circuit detection method executed in a load drive device including: a power storage element that stores electric power for driving a load; a first switch that is connected to a low-potential side of the load and controls a current flowing through the load; and a voltage detection circuit that detects a voltage of a current flow path flowing from the power storage element to a low-potential side power supply via the first switch. The load short-circuit detection method includes: PWM-driving the first switch at a predetermined duty ratio; and detecting that the load is being short-circuited in a case where a state in which the voltage of the current flow path detected by the voltage detection circuit is lower than or equal to a predetermined threshold voltage continues for a predetermined period of time or longer.

Abstract: The output voltage of a cathode drive-type semiconductor laser driving circuit is set to a minimum, power consumption by a driving circuit portion is suppressed, and the heat that is generated by the optical head or the optical disc device is reduced. In addition to a conventional configuration, the semiconductor laser driving circuit of the invention measures the cathode voltage (Vout) of a semiconductor laser (1) and controls the anode voltage (Vld) such that the cathode voltage (Vout) becomes a predetermined level, and by doing so sets the output voltage of the semiconductor laser driving circuit to a predetermined level in order to curtail power consumption by the driving circuit and minimize the rise in temperature of the optical head or the optical disc device.

Abstract: An optical pickup according to the present invention includes an integrated circuit element (LDD) 5 for driving first, second, and third semiconductor lasers 3, 4, and 5. The LDD 50 is shaped so as to have a rectangular principal face surrounded by one side, with a plurality of input/output pins being arranged along each side. The plurality of input/output pins include a first pin group connected to a blue-violet laser 5 whose oscillation wavelength is the shortest, a second pin group connected to a red laser 4, and a third pin group connected to an infrared laser 3. The wiring structure of the optical pickup includes a first transmission line 41 for connecting the first pin group to the blue-violet laser 5, a second transmission line 33 for connecting the second pin group to the red laser 4, and a third transmission line 31 for connecting the third pin group to the infrared laser 3, where the first transmission line 41 is shorter than both the second and third transmission lines 31 and 33.

Abstract: An output voltage of a cathode driving type semiconductor laser driving circuit is made minimum, power consumption of a driving circuit section is suppressed, and heat generation of an optical head or an optical disc device is reduced. In addition to the conventional constitution, the semiconductor laser driving circuit permits the output voltage of the semiconductor laser driving circuit to be at a prescribed level by measuring a cathode voltage (Vout) of a semiconductor laser (1) and controlling an anode voltage (Vld) so that the cathode voltage (Vout) is at the prescribed level, reduces power consumption of the driving circuit and suppresses temperature increase of the optical head or the optical disc device to be minimum.

Abstract: An optical pickup according to the present invention includes an integrated circuit element (LDD) 5 for driving first, second, and third semiconductor lasers 3, 4, and 5. The LDD 50 is shaped so as to have a rectangular principal face surrounded by one side, with a plurality of input/output pins being arranged along each side. The plurality of input/output pins include a first pin group connected to a blue-violet laser 5 whose oscillation wavelength is the shortest, a second pin group connected to a red laser 4, and a third pin group connected to an infrared laser 3. The wiring structure of the optical pickup includes a first transmission line 41 for connecting the first pin group to the blue-violet laser 5, a second transmission line 33 for connecting the second pin group to the red laser 4, and a third transmission line 31 for connecting the third pin group to the infrared laser 3, where the first transmission line 41 is shorter than both the second and third transmission lines 31 and 33.

Abstract: A laser driving device is provided that can support a higher speed and drives a semiconductor laser (3) to emit light in a pulse-like manner in accordance with a digital signal. The laser driving device includes a temperature sensor (5), a recording pulse generator (1), an auxiliary pulse generator (4), and an adder (8). The temperature sensor (5) produces a measured temperature that changes in accordance with a temperature of the semiconductor laser. The recording pulse generator (1), the auxiliary pulse generator (4), and the adder (8) produce a pulse-like signal having a shape corresponding to the measured temperature.

Abstract: An optical pickup according to the present invention includes an integrated circuit element (LDD) 5 for driving first, second, and third semiconductor lasers 3, 4, and 5. The LDD 50 is shaped so as to have a rectangular principal face surrounded by one side, with a plurality of input/output pins being arranged along each side. The plurality of input/output pins include a first pin group connected to a blue-violet laser 5 whose oscillation wavelength is the shortest, a second pin group connected to a red laser 4, and a third pin group connected to an infrared laser 3. The wiring structure of the optical pickup includes a first transmission line 41 for connecting the first pin group to the blue-violet laser 5, a second transmission line 33 for connecting the second pin group to the red laser 4, and a third transmission line 31 for connecting the third pin group to the infrared laser 3, where the first transmission line 41 is shorter than both the second and third transmission lines 31 and 33.

Abstract: When a light-receiving element receives a first laser beam, an output power detection unit detects a differential quantum efficiency value of the first laser beam. A control unit judges whether or not an intensity filter and a filter driving unit are operated in accordance with a control signal output from the control unit by using the differential quantum efficiency value from the output power detection unit.

Abstract: Provided is a semiconductor laser driving device which enables to reduce unnecessary power consumption. The laser driving device includes: a laser driving section for supplying a driving current for causing a semiconductor laser to emit light; a temperature detecting section for detecting a temperature of the semiconductor laser; and a voltage control section for supplying a source voltage to the laser driving section while changing a voltage value of the source voltage in accordance with the temperature detected by the temperature detecting section. As a result, unnecessary power consumption can be reduced. An appliance having the aforementioned information laser driving device will make energy savings possible, and further make it possible to suppress temperature increases of the appliance.

Abstract: A laser control unit, a laser control circuit and a laser-power adjustment method are provided which are capable of controlling laser power precisely, even if an error is produced in the duty of an optical pulse.

Abstract: Method for controlling a laser power used in recording on an optical disk includes: causing the laser to emit a test light emission pattern including a multipulse light emission interval and an at-bottom value continuous light emission interval; receiving the test light emission pattern of the laser to convert the pattern to an electric signal and to thereby obtain a light detection signal; calculating a detection value of a multipulse average value from the average value of the light detection signal, and calculating a bottom detection value from the light detection signal to obtain a light emission power characteristic of the laser on a supplied current based on the detection value of the multipulse average value and the bottom detection value; and controlling the current supplied to the laser based on the light emission power characteristic on the current supplied to the laser.

Abstract: In an optical disc drive, a laser light source emits a laser beam having an intensity changeable with the amount of drive current supplied. A first photodetector receives the laser beam reflected from an optical disc, thereby generating a readout signal. A second photodetector receives the laser beam, generates an electric signal representing the power of the laser beam received, and outputs the electric signal as a light quantity detection signal. A feedback control loop compares the level of the light quantity detection signal with a predetermined target value and regulates the drive current such that the level of the light quantity detection signal approaches the target value. In reading data from the optical disc, the target value is changed so as to compensate for a variation of the sensitivity of the second photodetector, thereby controlling the power of the laser beam emitted from the laser light source.

Abstract: A driving method of a semiconductor laser having an active layer region, a phase adjustment region and a distributed Bragg reflector region includes the steps of: calculating an average value of multipulse modulation currents modulated between a peak current and a bottom current input to said active layer region; calculating a difference between the average value of the multipulse modulation currents and a bias current input to the active layer region; and applying a first compensation current to the phase adjustment region when the multipulse modulation current is input to the active layer region, and applying a second compensation current corresponding to the difference to the phase adjustment region when the bias current is input to the active layer region.

Abstract: A light source device can attain a stable output of a harmonic even when there occurs a change in the ambient temperature or fluctuation in the output power. The light source device is provided with a semiconductor laser source (4), an optical waveguide-type QPM-SHG device (5) for generating a second harmonic from light emitted from the semiconductor laser source (4), a wavelength control means (7) for controlling a wavelength of light emitted from the semiconductor laser source (4), a means for slightly fluctuating wavelength (8) for changing a wavelength of light emitted from the semiconductor laser source (4) and a means for detecting a change in output light power of the optical waveguide-type QPM-SHG device (5) that occurs when a wavelength of light emitted from the semiconductor laser source (4) is changed.

Abstract: When a light-receiving element receives a first laser beam, an output power detection unit detects a differential quantum efficiency value of the first laser beam. A control unit judges whether or not an intensity filter and a filter driving unit are operated in accordance with a control signal output from the control unit by using the differential quantum efficiency value from the output power detection unit.

Abstract: In an optical disc drive, a laser light source emits a laser beam having an intensity changeable with the amount of drive current supplied. A first photodetector receives the laser beam reflected from an optical disc, thereby generating a readout signal. A second photodetector receives the laser beam, generates an electric signal representing the power of the laser beam received, and outputs the electric signal as a light quantity detection signal. A feedback control loop compares the level of the light quantity detection signal with a predetermined target value and regulates the drive current such that the level of the light quantity detection signal approaches the target value. In reading data from the optical disc, the target value is changed so as to compensate for a variation of the sensitivity of the second photodetector, thereby controlling the power of the laser beam emitted from the laser light source.

Abstract: A laser control unit, a laser control circuit and a laser-power adjustment method are provided which are capable of controlling laser power precisely, even if an error is produced in the duty of an optical pulse.

Abstract: A laser driving device is provided that can support a higher speed and drives a semiconductor laser (3) to emit light in a pulse-like manner in accordance with a digital signal. The laser driving device includes a temperature sensor (5), a recording pulse generator (1), an auxiliary pulse generator (4), and an adder (8). The temperature sensor (5) produces a measured temperature that changes in accordance with a temperature of the semiconductor laser. The recording pulse generator (1), the auxiliary pulse generator (4), and the adder (8) produce a pulse-like signal having a shape corresponding to the measured temperature.