Abstract: An optical pickup including a light detection element to divide light reflected from an optical recording medium into first through fourth light beam portions in a radial direction of the optical recording medium. From detection signals from the light detection element, a reproduction signal detection portion detects an information signal, and a tracking error signal detection portion detects a tracking error signal. The light source emits light that is focused as a single light spot on a main track of the optical recording medium. The tracking error signal detection portion gain controls and sums push-pull signals from the detection signals to detect, during a recording operation, a tracking error signal with reduced push-pull offset without erasing existing signals on adjacent tracks. The reproduction signal detection portion sums and gain controls the detection signals to detect an information signal containing reduced crosstalk from adjacent tracks.

Abstract: An optical pickup includes an aberration correction element to correct chromatic aberration caused by variation of power from a light source when changing between operating modes in a recording medium. The aberration correction includes a first retardation member, which includes a stepped convex pattern with a plurality of steps at one side, and a second retardation member combined with the first retardation member. The second retardation member includes a stepped concave pattern with a plurality of steps at one side facing the first retardation member, the stepped concave pattern corresponding to the stepped convex pattern. The first and the second retardation members include different refractive indices for a light beam, which allows the first and the second retardation members to selectively create a phase difference of an incident light beam according to a polarization of the incident light beam.

Abstract: An optical disk with an improved structure of an information pit, and a method of manufacturing the same. The optical disk has projections respectively projecting from bottom surfaces of a plurality of information pits. Also, in the optical disk, laser beams irradiated onto the information pits from an optical pickup to read information recorded on the optical disk are scattered by the projections. Thus, among the laser beams irradiated onto the information pits, the laser beams reflected toward the optical pickup are largely decreased, so that an amplitude and resolution of a reproduced signal are greatly increased, thereby significantly improving reproduction characteristics of the optical disk.

Abstract: An objective lens includes an aspherical lens facing a disk and having a predetermined first focal distance and a predetermined numerical aperture, and a holographic lens installed adjacent to the aspherical lens and having a second focal distance longer than that of the first focal distance and having a diffraction lattice to compensate for the chromatism due to a change in wavelength of laser light having a wavelength of 670 nm or less. Thus, during the shift between recoding and reproduction of a DVD or an HD-DVD, the change in wavelength due to the change in power of the laser light and chromatism according to the change can be effectively corrected. Also, since the objective lens is formed of one aspherical lens and one holographic lens, the material for each of the lenses can be easily selected and also the structure of the optical pickup using the objective lens according to the present invention can be simplified.

Abstract: An optical pickup compatible with optical discs having different formats. A first light source emits a first light beam suitable for a first format optical disc. An objective lens is optimized for a wavelength of the first light source. Light reflected from the first optical disc provides a reproduction signal. A second light source emits a second light beam suitable for a second format optical disc. A light splitter splits the second light beam and the objective lens focuses the split beams onto the second disc as a main light spot and a sub-light spot. Lights reflected from the main light spot and the sub-light spot are independently detected and then processed to correct for chromatic aberration caused by a difference in the wavelengths of the first and second light beams and/or spherical aberration caused by thickness difference between the first and second format optical discs.

Abstract: An optical pickup capable of focusing a main light spot and an auxiliary light spot including optical aberration when an optical disk is not tilted, and analyzing the main light spot and the auxiliary light spot with a photodetector, thereby correcting aberration.

Abstract: An optical disk with an improved structure of an information pit, and a method of manufacturing the same. The optical disk has projections respectively projecting from bottom surfaces of a plurality of information pits. Also, in the optical disk, laser beams irradiated onto the information pits from an optical pickup to read information recorded on the optical disk are scattered by the projections. Thus, among the laser beams irradiated onto the information pits, the laser beams reflected toward the optical pickup are largely decreased, so that an amplitude and resolution of a reproduced signal are greatly increased, thereby significantly improving reproduction characteristics of the optical disk.

Abstract: A refrigerator having freezing and refrigerating compartments and a refrigerating H.M. cycle and a control method therefor, comprises a compressor for compressing refrigerant, a condenser for condensing refrigerant, a capillary tube for expanding refrigerant, a first evaporator mounted in the refrigerating compartment and a second evaporator mounted in series to the first evaporator in the freezing compartment; the freezing and refrigerating compartments divided from each other to be cooled, separately, a first fan mounted in the refrigerating compartment to circulate air passing through the first evaporator, a second fan mounted in the freezing compartment to circulate air passing through the second evaporator, and a control portion for controlling the operation of the compressor and the freezing and refrigerating fans, thereby performing both compartments to be maintained at the constant temperature.

Abstract: A refrigerator includes first, and second compartments cooled to different temperatures. A first evaporator and first fan are provided in the first compartment, and a second evaporator and second fan are provided in the second compartment. A first switch controls the supply of electrical power to a compressor, the first fan, and the second switch. The second switch is operable to turn on/off the second fan while power is supplied to the compressor and first switch.

Abstract: A refrigerator includes a freezing compartment and a separate refrigerating compartment. A pair of evaporators is associated with the freezing and compartments, respectively. Each evaporator has a fan associated therewith. A compressor is connected to both of the evaporators. The compressors and fans are all electrically connected in parallel and operated simultaneously when the temperature in a selected one of the compartments is above a reference temperature. The selected compartment can be either the refrigerating compartment or the freezing compartment.

Abstract: A refrigerator includes a compressor, and freezing and refrigerating compartments, each compartment having its own evaporator and fan. Only one of those fans can be operated at any given time. To operate the refrigerator, an actual temperature of a first of the compartments (either the freezing compartment or the refrigerating compartment) is compared with a reference temperature. If the actual temperature is lower than the reference temperature, then neither of the fans is operated. If the actual temperature is greater than the reference temperature, then an actual temperature of the second compartment is compared with a reference temperature. If the actual temperature of the second compartment is higher than its respective reference temperature, then the fan of only the second compartment is operated; otherwise, the fan of only the first compartment is operated.