Abstract: To provide an optical head unit which is configured to provide a reproduce signal when reproducing information from a recording medium of a corresponding standard by selectively using laser beams with different wavelengths, an optical diffraction element is provided, in which the grooves of a binary diffraction grating mainly for a laser beam with a wavelength of 655 nm and a blazed diffraction grating mainly for a laser beam with a wavelength of 405 nm are defined substantially parallel, and the reflected laser beams of the laser beams with respective wavelengths reflected by a corresponding optical disc are guided to a substantially the same detection area or detection areas positioned very close to one another in a photodetector.

Abstract: To provide an optical head unit which is configured to provide a reproducing signal difficult to be influenced by vibrations when reproducing information from a recording medium of a corresponding standard by selectively using laser beams with different wavelengths, the distance between a beam split phase of a beam splitter and a photodetector is reduced by providing a ball lens on a beam split plane defined not parallel and not vertical to an axial line connecting an optical coupling prism and a beam splitter, and reducing the distance between a photodetector and a beam split plane of a beam splitter, as an embodiment of a disc apparatus.

Abstract: To have laser light sources with different wavelengths as one body, to guide the optical axes of the laser light sources through a common optics as far as possible, and to realize compactness, manufacturing easiness, low cost and high performance and reliability, when the wavelengths of laser beams from first, second and third light sources 21, 22, and 23 are different, a laser beam with a shortest wavelength is output from the first light source, a laser beam with a intermediate wavelength is output from the second light source, and a laser beam with a longest wavelength is output from the third light source. In this arrangement, a laser beam from the light source with a shortest wavelength is reflected by the least number of times.

Abstract: An automotive electric power unit is provided to reduce the occurrence of electromagnetic noise caused by change in magnetic fields when the current dropps to zero when an ignition switch is being switched off. When the ignition switch is switched off, an input voltage to an ON/OFF control terminal of a DC/DC converter gently decreases through a potential difference between terminals of a motor driving load connected thereto. Accordingly, a control device, for which a detecting voltage is set relatively high, first detects an OFF state of the ignition switch and disconnects power loads such as a cooling fan, air conditioner, and defroster from the DC/DC converter by regulating relays. Then, the DC/DC converter, for which a detecting voltage is set lower than the detecting voltage for the control device, detects the OFF state of the ignition switch and stops stepping down the voltage so that a charging current for a battery of the load current thereof is shut off.

Abstract: An optical pickup device has first emission unit emits first laser beam, second emission unit emits second laser beam whose wavelength is different from that of first laser beam, to same optical axis to first laser beam is emitted, objective lens collects first and second laser beams emitted from first and second emission units and emits collected light to information recording medium, wavefront converting unit arranged on routes of respective reflected lights of first and second laser beams from information recording medium, wavefront converting unit receiving reflected lights of first and second laser beams and selectively wavefront converting at least one of reflected lights, and light receiving unit receives at least one of reflected lights of first and second laser beams having passed through wavefront converting unit, and outputs detection signal corresponding thereto.

Abstract: An automotive electric power unit is provided to reduce the occurrence of electromagnetic noise caused by change in magnetic fields when the current dropps to zero when an ignition switch is being switched off. When the ignition switch is switched off, an input voltage to an ON/OFF control terminal of a DC/DC converter gently decreases through a potential difference between terminals of a motor driving load connected thereto. Accordingly, a control device, for which a detecting voltage is set relatively high, first detects an OFF state of the ignition switch and disconnects power loads such as a cooling fan, air conditioner, and defroster from the DC/DC converter by regulating relays. Then, the DC/DC converter, for which a detecting voltage is set lower than the detecting voltage for the control device, detects the OFF state of the ignition switch and stops stepping down the voltage so that a charging current for a battery of the load current thereof is shut off.