Abstract: An optical pickup actuator comprises a lens holder having an object lens which focuses a laser beam onto an optical information storage medium mounted thereon. In the optical pickup actuator the lens holder is movably supported by a support member with respect to a base. The optical pickup actuator also comprises a magnetic circuit to drive the lens holder in a focusing direction and a tilt direction independently.

Abstract: An optical pickup actuator, including a lens holder movably installed on a base, and mounted with an objective lens to transmit an incident light to an optical information recording medium, and a magnetic circuit to independently drive the lens holder in a focusing direction, a tilting direction and a tracking direction, respectively.

Abstract: An optical pickup apparatus according to an embodiment of the present invention, comprises an optical unit for projecting a plurality of wavelengths of light, the light including a celadon light, toward a recording medium and receiving the light reflected from the recording medium to thereby detect an information signal and an error signal, and a compatible objective lens for focusing a light projected from the optical unit to thereby form an optical spot on a recording surface of the recording medium and applying at least three light having different wavelength ranges to be compatibly used for both the high-density and the low-density recording mediums. Accordingly, the optical pickup apparatus is capable of compatibly employing a high-density recording medium, which uses a celadon light and is slimmer than a digital versatile disc (DVD), and at least one low-density recording medium.

Abstract: A memory module, a memory unit, and a hub with a non-periodic clock and methods for using the same. An example memory module may include a phased locked loop, receiving an external, periodic clock and generating one or more internal periodic clocks and a plurality of memory units, receiving one of the internal periodic clocks or a non-periodic clock from an external source.

Abstract: An optical pickup actuator and a method of assembling the same is provided. The method of assembling the optical pickup actuator comprises the steps of providing a blade having at least one objective lens mounting area and an aberration correcting mechanism mounting area, arranging an objective lens in the objective lens mounting area, positioning an aberration correcting mechanism in the aberration correcting mechanism mounting area such that the central point of the aberration correcting mechanism coincides with the central point of the objective lens, tuning the aberration correction mechanism, and adhering the aberration correcting mechanism using an adhesive.

Abstract: A memory module test system including at least one memory module. The at least one memory module includes a first hub and a plurality of semiconductor memory devices. The system includes a tester for testing the at least one memory module. A second hub is located between the first hub and the tester. The second hub is for converting a memory command and memory data output from the tester into packet data and transmits the packet data to the first hub. The second hub converts the packet data output from the first hub into memory data and transmits the memory data to the tester.

Abstract: A memory module testing apparatus and method include a test slot adapted to receive a target memory module, wherein the target memory module includes a first memory unit to store information related to the target memory module. The memory module testing apparatus further includes a second memory unit adapted to store information related to a memory module, and a first switching unit adapted to selectively provide a driving signal to at least one of the first memory unit and the second memory unit.

Abstract: A semiconductor memory module and a semiconductor memory device are disclosed. In one embodiment, the invention provides a semiconductor memory module comprising a circuit board, a plurality of semiconductor memory devices adapted to operate during a test mode and a normal operation mode and mounted on the circuit board, a first signal line set comprising a plurality of first signal lines connected to the plurality of semiconductor memory devices, and a plurality of second signal line sets. Each semiconductor memory device comprises first terminals adapted to receive first signals from the first signal lines, second terminals connected to a corresponding one of the second signal line sets, a third terminal adapted to receive an enable signal during the test mode, and a signal transmitting unit adapted to output second signals to the second terminals in response to the enable signal.

Abstract: An optical pickup device includes a light source to emit light, an objective lens to focus the light on a recording medium to form a light spot, an optical path changer on an optical path between the light source and the objective lens to change the path of incident light, a chromatic aberration correction lens disposed on an optical path between the light source and the objective lens, and a photodetector to receive light which is reflected from the recording medium and is then incident thereon through the optical path changer. The chromatic aberration correction lens corrects a chromatic aberration occurring due to a change in the wavelength and/or due to an increase in a wavelength bandwidth of the light. The chromatic aberration correction lens includes at least two lenses such that a lens having a positive power and a lens having a negative power are adjacent to each other.

Abstract: An optical pick-up actuator capable of a tilt operation. The optical pick-up actuator has a triaxial magnetic driving portion installed on a movable portion and a supporting portion to move the movable portion in a focusing direction and a tracking direction and tilt the movable portion. The triaxial magnetic driving portion includes a pair of focusing/tilting driving magnets, a pair of tracking driving magnets, focusing coils, a pair of tilt coils, and a pair of tracking coils. The pair of tilt coils installed on the movable portion each face one of the pair of focusing/tilting driving magnets and are wired independently from the pair of focusing coils.

Abstract: A compatible optical pickup compatibly using a high density recording medium and at least one low density recording medium, includes an objective lens to form a light spot suitable for use on a recording surface of the high density recording medium by focusing a corresponding incident light beam with a high NA suitable for the high density recording medium and a light spot suitable for use on another recording surface of the low density recording medium by focusing another corresponding incident light beam, and an actuator provided to apply tilt to the objective lens. The light beam for the low density recording medium is incident on the objective lens as a divergent beam. When the objective lens is shifted in a radial direction, a tilt is applied to the objective lens corresponding to the shift.

Abstract: There is provided an output buffer circuit for a semiconductor memory device. The output buffer circuit includes: a main buffer and parallel connected auxiliary buffer receiving an input signal. A selection circuit controls the auxiliary buffer by selectively defining a selected input signal in relation to the input signal and an adjacent input signal.

Abstract: An optical pickup including an optical member which inhibits interference light reflected from an adjacent layer from being received by a photodetector when an optical information storage medium includes a plurality of recording layers on at least one side thereof. The optical pickup suppresses a photodetector, especially first and second sub-photodetectors of the photodetector, from receiving the interference light reflected from the adjacent layer.

Abstract: A compatible optical pickup includes an optical disc, an objective lens, a diffractive device, and a divergent lens. The optical unit emits a short wavelength light beam corresponding to a high density optical disc and a long wavelength light beam corresponding to a low density optical disc. The objective lens forms a light spot on the high density optical disc and the low density optical disc and the diffractive device diffracts the short wavelength light beam to correct chromatism according to a change in a wavelength of the short wavelength light beam. The divergent lens refracts the long wavelength light beam toward the objective lens to increase a working distance with respect to the low density optical disc.

Abstract: A memory module and related method are disclosed. The memory module comprises a clock generator configured to generate first and second internal clock signals in relation to an external clock signal, and a register configured to receive the first and second internal clock signals. The register stores an external control/address signal in response to the first internal clock signal and transmits an internal control/address signal derived from the external control/address in response to the second internal control/address signal.

Abstract: An optical pickup device includes a light source to emit light, an objective lens to focus the light on a recording medium to form a light spot, an optical path changer on an optical path between the light source and the objective lens to change the path of incident light, a chromatic aberration correction lens disposed on an optical path between the light source and the objective lens, and a photodetector to receive light which is reflected from the recording medium and is then incident thereon through the optical path changer. The chromatic aberration correction lens corrects a chromatic aberration occurring due to a change in the wavelength and/or due to an increase in a wavelength bandwidth of the light. The chromatic aberration correction lens includes at least two lenses such that a lens having a positive power and a lens having a negative power are adjacent to each other.

Abstract: A multi-mode electrostatic discharge (ESD) circuit for a semiconductor chip comprises first and second ESD diodes. In a first mode, a body voltage greater than a power source voltage of the semiconductor chip is applied to the first ESD diode and a body voltage less than a ground voltage of the semiconductor chip is applied to the second ESD diode. In a second mode, a body voltage substantially equal to the power source voltage of the semiconductor chip is applied to the body of the first ESD diode and a body voltage substantially equal to the ground voltage of the semiconductor chip is applied to the second ESD diode.

Abstract: An optical pickup having a plurality of objective lenses. At least one of the plurality of objective lenses is configured so that a type of wavefront error mainly generated by a tilt of the at least one of the plurality of objective lenses is the same as a type of a wavefront error mainly generated by an angle at which light is incident upon the at least one of the plurality of objective lenses.

Abstract: An optical disc apparatus and a wobble signal detection method in which a light beam projected onto an optical disc and reflected by the optical disc is divided into at least four light regions in the direction corresponding to the radial direction of the optical disc to detect the light regions, and a wobble signal is detected by performing a subtraction on first and second difference signals, the first difference signal obtained by performing a subtraction on detection signals for the inner light regions of the divided and/or detected light beam and the second difference signal obtained by performing a subtraction on detection signals for the outer light regions of the divided and/or detected light beam.

Abstract: A semiconductor memory module and a semiconductor memory device are disclosed. In one embodiment, the invention provides a semiconductor memory module comprising a circuit board, a plurality of semiconductor memory devices adapted to operate during a test mode and a normal operation mode and mounted on the circuit board, a first signal line set comprising a plurality of first signal lines connected to the plurality of semiconductor memory devices, and a plurality of second signal line sets. Each semiconductor memory device comprises first terminals adapted to receive first signals from the first signal lines, second terminals connected to a corresponding one of the second signal line sets, a third terminal adapted to receive an enable signal during the test mode, and a signal transmitting unit adapted to output second signals to the second terminals in response to the enable signal.