Global Oled Technology LLC

Mitsumi Electric Company Ltd.

Mitburri Electric Co., Ltd

Yuichi Maekawa

Koichi Miwa

Kenichi Furukawa

Checking failures in transistors including driving transistors, switching transistors, and sampling transistors before light emitting elements are formed in a display device. I-V characteristics including threshold voltage of the driving transistorC in one pixel circuit can be detected. In a pixel circuit, the sampling transistorA and switching transistorD are made conductive and the signal potential is given to the gate electrode of the driving transistorC from the signal line DTCm. At this time, the current which flows between the drain electrode and source electrode of driving transistorC flows through the switching transistorD and a reference potential line Vref_r to a test point, and is measured by a current measuring device connected to the test point.

Pixel circuit, display device, and inspection method

Compensate for the variations of threshold voltage of a driving transistor. During the period of the reference signal voltage Vref being set to the signal line DTC, voltage between the gate and source of the driving transistorC is made equal to or greater than the threshold voltage of the driving transistorC, and the difference in voltage of the reference signal voltage Vref and the reference power supply voltage Vref_r is charged to the retentive capacitanceB. At the same time, the voltage of the source of the said driving transistorC is set to the reference power supply voltage Vref_r to make the voltage applied to the light emitting elementE equal to or lower than its threshold voltage, a voltage corresponding to the threshold voltage of the driving transistorC is held in the retentive capacitanceB. During a period of time when a display signal voltage is set to the signal line DTC, the sampling transistorA is conducting, so as to sample the signal voltage, and this signal voltage is superposed on the threshold voltage held in the retentive capacitance.

A display device in which a plurality of pixels are arranged in a matrix form, corresponding to intersections of a plurality of data lines and a plurality of scan lines, wherein each pixel includes a light emitting element having a first electrode connected to a first power supply and which emits light according to a current that flows; a driving transistor having a source electrode connected to a second power supply and which supplies a drain current to a second electrode of the light emitting element; a data storage capacitor having a first electrode connected to a gate electrode of the driving transistor; and a first switch which is switched ON during a pixel selection period so that data of a data line is written to the data storage capacitor, and wherein a potential of a second electrode of the data storage capacitor is changed.

Display device and pixel circuit

To efficiently compensate a threshold value of a driving transistor. In a state where a first switching transistor is non-conductive and a second switching transistor in conductive, a sampling transistor is made conductive and a reference voltage is supplied from a signal line to write a threshold voltage of a driving transistor to a first capacitance. After that, in a state where first and second switching transistors and are non-conductive, the sampling transistor is made conductive and a signal voltage from the signal line is written to the first capacitance. Further, after that the sampling transistor is put into a non-conductive state, and the first and second switching transistors are put in a conductive state, to drive the driving transistor and supply current to a light emitting element.

A method for adjusting a focus bias in an optical disc drive comprises the steps of: rotationally driving an optical disc in a state that only focus servo is engaged without engaging tracking servo; driving an actuator of an optical pick-up so that a laser beam projected from the optical pick-up is moved in a tracking direction to obtain an HF signal; and determining a focus bias by which a proper focusing point can be obtained based on the HF signal. The driving of the actuator is carried out by supplying an actuator drive control signal to a tracking actuator of the optical pick-up in a state that tracking servo is not engaged.

Method for adjusting focus bias in optical disc drive and optical disc drive that can implement the method

An optical disc drive that can carry out recording data to an optical disc such as a format procedure of the optical disc in a relatively short time is provided. An optical disc drivehas a rotation driving mechanism for rotating a loaded optical discat any one of multiple rotational speed (rotation number) levels, an optical pick-upcapable of moving in a radial direction of the loaded optical discto overwrite information (data) onto the optical discby emitting a laser beam thereto, and an optical pick-up moving mechanism including a sled motorfor moving the optical pick-upin the radial direction of the optical disc. In a case that the optical discis a blank disc having no recording history, i.e., in a case of a first recording procedure of the optical disc, the optical disc drivecarries out recording at a recording speed higher than the highest recording speed for overwriting.

Optical disc drive

An optical power level-controlling device controls optical power level of a laser beam irradiated on an optical disk. The optical power level takes an ERASE (reference) level, a lower BIAS level and a higher WRITE level. Recording is performed by alternating the optical power level between BIAS and WRITE levels. In a controlling part, test signals are recorded while varying the optical power level and in an OPC for setting an optimum WRITE level by reproducing the test signals. A combined control, i.e., combination of a feedback control and a fixed value control at a predetermined ratio, is performed on BIAS level during a recording operation of the test signals. Fixed value control is performed on the difference between ERASE level and BIAS level during a recording operation.

Optical power level-controlling device for stable oscillation of laser diode

An optical disc drive equipped with a TLN signal generating apparatus is disclosed. The TLN signal generating apparatus includes a TLN signal generating circuit for generating a TLN signal (track loss signal) based on signals obtained from an optical pick-up; a digitizing circuit for digitizing the TLN signal by comparing it with a reference level; and a correction circuit for correcting the TLN signal so that it is accurately digitized by the digitizing circuit irrespective of an offset component which is a direct current component contained in the TLN signal. The correction circuit is comprised of an offset component detecting circuit for detecting a level of the offset component contained in the TLN signal; and a signal control circuit for controlling, responsive to the level of the offset component detected by the offset component detecting circuit, a level of the TLN signal generated by the TLN signal generating circuit so that the level of the TLN signal will become a level which does not receive any influence from the level of the direct component. The correction circuit can also be comprised of a signal correcting circuit which amplifies an alternating current component contained in the TLN signal without eliminating a directed current component contained in the TLN signal.

TLN SIGNAL GENERATING APPARATUS USED IN OPTICAL DISC DRIVE AND OPTICAL DISC DRIVE EQUIPPED WITH THE APPARATUS, AND OPTICAL DISC DRIVE EQUIPPED WITH AMPLITUDE ADJUSTING APPARATUS FOR TRACKING ERROR SIGNAL

Growing community of inventors

Kanagawa, Japan

Yuichi Maekawa