Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Hisashi Senga

Hiromichi Ishibashi

Toshio Matsumoto

Shigeru Furumiya

Ken'ichi Kasazumi

Takeharu Yamamoto

Kenzo Ishibashi

Kazuhisa Yamamoto

Kiminori Mizuuchi

Yasuo Kitaoka

Hideki Hayashi

Tetsuya Shihara

Tomotada Kamei

Yohichi Saitoh

Tosifumi Yokoyama

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 () 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.

Semiconductor laser driving circuit, and optical disc device and integrated circuit provided with semiconductor laser driving circuit

An optical pickup according to the present invention includes an integrated circuit element (LDD)for driving first, second, and third semiconductor lasers, and. The LDDis 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 laserwhose oscillation wavelength is the shortest, a second pin group connected to a red laser, and a third pin group connected to an infrared laser. The wiring structure of the optical pickup includes a first transmission linefor connecting the first pin group to the blue-violet laser, a second transmission linefor connecting the second pin group to the red laser, and a third transmission linefor connecting the third pin group to the infrared laser, where the first transmission lineis shorter than both the second and third transmission linesand. Of the rectangular principal face of the LDD, the side along which the first pin group is provided is orthogonal to the side along which the second pin group is provided or to the side along which the third pin group is provided.

Optical pickup and optical disc device

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.

Optical recording/reproducing apparatus with transmission amount variation unit

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. A light-receiving elementconverts the optical pulse into an electric signal and outputs a photo-detection signal; an LPFcalculates the average value of the optical pulse, based on the photo-detection signal; a DSPcalculates a light-emission power value, based on the average value of the optical pulse and the duty of the optical pulse, and calculates the difference between the light-emission power value and a target power value; an EP-ROMstores a correction value for correcting a calculation which is executed by the DSP; the DSPcorrects the calculation, based on the correction value, and controls an electric-current value which is supplied to a semiconductor laser, based on the calculation result which is obtained from the correction; and a laser drive circuitdrives the semiconductor laser, based on the electric-current value.

Laser control unit, laser control circuit, and laser-power adjustment method

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.

Method and apparatus for controlling laser power using a test light emission pattern having a multipulse light emission interval

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.

Optical disc drive for controlling laser emission

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.

Driving method and driving circuit of light source apparatus

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 (), an optical waveguide-type QPM-SHG device () for generating a second harmonic from light emitted from the semiconductor laser source (), a wavelength control means () for controlling a wavelength of light emitted from the semiconductor laser source (), a means for slightly fluctuating wavelength () for changing a wavelength of light emitted from the semiconductor laser source () and a means for detecting a change in output light power of the optical waveguide-type QPM-SHG device () that occurs when a wavelength of light emitted from the semiconductor laser source () is changed. In this case, a wavelength of light emitted from the semiconductor laser source () is controlled to an optimum wavelength of the optical waveguide-type QPM-SHG device () based on a change in output light power of the optical waveguide-type QPM-SHG device () that occurs when a wavelength of light emitted from the semiconductor laser source () is changed.

Light source apparatus and its control method

A pulse emitting laser is constantly controlled while recording data continuously to a desired power level without using test emissions or a high speed sample hold filter. The laser drive method detects beam emission power from a light source and generates a monitor wave; receives data and generates an expected wave for the beam power based on the received data; calculates the difference between the generated monitor wave and the expected wave; controls current flow from the bias current source based on the calculated waveform difference; and finally emits a beam from the light source based on the controlled current flow of the bias current source.

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Osaka, Japan

Hisashi Senga