Abstract: A laser power control apparatus and method prevent fluctuation in the level of laser power due to a difference between reaction speeds of an automatic power controller according to write speeds of a disc drive. In the apparatus and method, laser power can be automatically controlled to prevent a variation in the level of laser diode driving voltage in read power periods, according to the write speeds of a disc drive, in a write mode. Thus, it is possible to prevent unstable operations of a servo circuit due to a variation of the level of laser power and further, prevent deterioration in the quality of the servo circuit due to a variation in the level of a wobble signal, thereby stabilizing recording characteristics of the disc drive.

Abstract: Provided are an organic light-emitting compound of Formula 1 and an organic light-emitting device using the organic light-emitting compound: where Ar, R1, R2, R3, R4, and R5 are the same as defined in the detailed description. The organic light-emitting device manufactured using the organic light-emitting compound has a low turn-on voltage and high efficiency and color purity.

Abstract: A method of controlling a recording speed of an optical disc recording system includes detecting error information with respect to a level of a servo control signal of the optical disc recording system, and adjusting the recording speed of the optical disc recording system with reference to the error information.

Abstract: A method of and an apparatus for controlling a power of a light emitter in an optical disc drive to stabilize a servo control operation by efficiently compensating a slow tail effect occurring in a photodiode monitoring outputs of the light emitter are provided. The method includes: detecting an intensity of a laser signal reflected from a recording medium; normalizing the reference value using the detected value; and adjusting the reference value using the normalization result.

Abstract: A laser power control apparatus and method prevent fluctuation in the level of laser power due to a difference between reaction speeds of an automatic power controller according to write speeds of a disc drive. In the apparatus and method, laser power can be automatically controlled to prevent a variation in the level of laser diode driving voltage in read power periods, according to the write speeds of a disc drive, in a write mode. Thus, it is possible to prevent unstable operations of a servo circuit due to a variation of the level of laser power and further, prevent deterioration in the quality of the servo circuit due to a variation in the level of a wobble signal, thereby stabilizing recording characteristics of the disc drive.

Abstract: An apparatus for changing a recording speed of an optical recording medium by analyzing wobble signals in real time during a recording operation, includes a signal process unit which outputs a cyclic redundancy check (CRC) signal that checks for a generation of errors on the optical recording medium from absolute time in pregroove (ATIP) information output from the optical recording medium during the recording operation, and a speed control unit which changes the recording speed during the recording operation according to a comparison of the CRC signal output from the signal process unit with a reference value. In the apparatus, the recording speed is limited or lowered in response to a signal quality of a recording section being less than an acceptable level during the recording operation. Accordingly, buffer under run and defects of read-in start position and seek fail, which are generated during a ZCLV operation, are prevented.