Sharp Kabushiki Kaisha Corporation

Toshihiro Ohba

Hisashi Uede

Yoshiharu Kanatani

Hiroshi Kishishita

Shigeyuki Harada

Atsushi Sakamoto

Hiroshi Kinoshita

Kazuo Shoji

Yoshihide Fujioka

Masashi Kawaguchi

Shuhei Yasuda

Yosihide Fujioka

Shuji Inada

Hidetoshi Maeda

Akio Inohara

Kinichi Isaka

Yoshiyuki Kokuhata

Ikuo Ogawa

Hiromasa Asada

Kyoichi Yamamoto

Hisashi Yamaguchi

Masayoshi Koba

Jun Kudo

Takahiro Senda

Seiji Ohhashi

Norio Yasunishi

Koki Taniguchi

Chuji Suzuki

Hiroyuki Shimoyama

Kiyohisa Matsui

Morihisa Sogabe

Hisashi Ueda

Kioichi Yamamoto

Chugi Suzuki

In a pixel circuit, a switching TFT, a driving TFT, and an organic EL elementare provided between a power supply wiring line Vp and a common cathode Vcom and a capacitorand a switching TFTare provided between a gate terminal of the driving TFTand a data line Sj. A switching TFTis provided between a connection point A between the capacitorand the switching TFTand a power supply wiring line Vr, a switching TFTis provided between the gate and drain terminals of the driving TFT, and a capacitoris provided between the gate terminal of the driving TFTand the power supply wiring line Vr. Thus, a display device is provided that can freely set a period during which variations in the threshold voltage of a drive element are compensated for, and performs high-quality display by holding a control terminal potential of the drive element during light emission from an electro-optical element.

Electric current driving type display device and pixel circuit

In a display device such as a thin-film EL display device, etc. formed with a dielectric layer disposed between a plurality of scanning side electrodes and a plurality of data side electrodes in the direction for them intersecting to each other, a modulation voltage, varied according to gradation display data is applied to the data side electrodes, and a positive or negative writing voltage is applied to the scanning side electrodes in a line order for a gradation display different in brightness. Binary coded signals corresponding to each gradation of a gradation display are used as the gradation display data. The logical value of the binary coded signal is inverted according to the polarity of the writing voltage. Thus, a common gradation display can be performed from one binary coded signal for both the negative driving that applies a negative writing voltage and the positive driving that applies a positive writing voltage. As a result, by only by adding a data conversion circuit for inverting a binary coded signal, the function that converts the correspondence relation between the gradation to be displayed and the gradation display data depending on the negative driving or positive driving can be incorporated.

Method and apparatus for driving display device

A liquid crystal display device includes a liquid crystal panel having a plurality of scanning electrodes including first and second scanning electrodes, a plurality of signal electrodes including a first signal electrode, and a liquid crystal layer. A display is generated based on display data including first and second display data. The liquid crystal display device further includes a scanning electrode driver which outputs a scanning voltage to the first scanning electrode in a first scanning period and outputs a scanning voltage to the second scanning electrode in a second scanning period following the first scanning period. A signal electrode driver outputs a first voltage corresponding to the first display data to the first signal electrode in the first scanning period and outputs a second voltage corresponding to the second display data to the first signal electrode in the second scanning period. The signal electrode driver compares the first display data and the second display data and, when the first display data and the second display data are different, outputs a third voltage for correcting a reduction of an effective voltage of the second voltage for a correction duration in the second scanning period.

Liquid crystal display device

A driving method for a liquid crystal display is provided with the steps of (a) applying a row select voltage to each of the row electrodes simultaneously, the row select voltage corresponding to an element of an orthogonal matrix and being either +1 or -1 ; (b) conducting an exclusive-or operation with respect to each element of a row select vector and a display vector, the row select vector indicating the row select voltages by vector notation and the display vector indicating a display data by the vector notation, and conducting a summation of each exclusive-or operation; (c) applying to the column electrode a voltage of a level which varies depending on the summation so as to simultaneously drive the plurality of rows; and (d) in a case where all the display data correspond to ON display or OFF display in the step (c), assigning the row select voltage, applied to either the selected row electrode having the lowest select voltage among driving voltages within one frame period for the ON display or the selected row electrode having the highest select voltage among the driving voltages within one frame period for the OFF display, to a virtual row electrode outside a display area, and applying a virtual display data to the virtual row electrode.

Driving method for a liquid crystal display

A display device, such as thin film EL display device, is formed by interposing a dielectric layer between a plurality of scanning electrodes and a plurality of data electrodes which are arranged at right angles. Modulation voltage is varied in accordance to the display data, and is applied to the data electrodes. Further, a writing voltage is applied to the scanning electrodes in sequential line order, to thereby perform gradation display. Further, the writing voltage includes a ramp voltage, which varies with time. Thus, the peak of the current flowing through the luminescent layer of the picture element, as a current contributing to the luminescence, is suppressed to a low level. contributing to the luminescence, is suppressed to a low level. Accordingly, the energization period of the current is also elongated. Thus gradation display over multiple levels is made possible and a stable display of different gradation levels is enabled.

Method and apparatus for driving a display device

This invention relates to gradation display by a pulse width control method (PWM method) in every pixel in a capacitive display apparatus such as a liquid crystal display apparatus. The driving voltage applied to the electrodes is varied slowly, and the number of gradations of gradation display by the PWM method is increased. Since the capacitive display apparatus is used, for each electrode further from the drive circuit, the driving pulse is more influenced and its persisting duration is extended. As a result, even in identical gradation data, uneven colors may occur. The pulse width applied to the electrodes is gradually decreased as scanning of the electrodes sequentially occurs. Therefore, the brightness of the capacitive display apparatus may be made uniform over the entire screen surface.

Method and apparatus for driving capacitive display device

In accordance with the invention, gradation display is performed for each picture element in capacitive display apparatuses such as EL display apparatus by means of pulse width modulation. In doing so, pulse duration of the voltage applied to one group of electrodes among the a plurality of electrodes arranged in matrix is so set as to span over two scanning periods, during which another group of electrodes which are grouped into pairs each of two adjacent lines are scanned successively. This reduces the number of drive voltage charge and discharge cycles. Consequently power consumption of the display apparatus of PWM system can be controlled to a low level.

Method and apparatus for driving display apparatus

A display unit includes a thin film EL display panel, a scanning side switching circuit connected to a scanning side electrode, a data side switching circuit connected to a data side electrode, a scanning side drive circuit which outputs a high voltage pulse to the scanning side switching circuit and a data side drive circuit which outputs a signal voltage to the data side switching circuit. It further includes a device for decreasing a pulse width of a high voltage pulse supplied from the scanning side drive circuit to the scanning side switching circuit in accordance with an increase of the level of a high voltage generated by a high voltage power supply in the scanning side drive circuit.

Display unit having brightness control function

A method of driving a display device with a plurality of scanning side electrodes and a plurality of data side electrodes which are disposed in directions intersecting each other, and a dielectric layer interposed between the scanning side electrodes and the data side electrodes, and including steps of applying modulation voltages corresponding to display data to the data side electrodes, and also applying writing voltages of positive or negative polarity to the scanning side electrodes through line sequence, so as to cause picture elements composed of the dielectric layer to emit light. The driving method further includes steps of thinning out the display data, and applying a plurality of kinds of modulation voltages different in amplitude according to each frame, so as to cause the picture elements to effect gradation display of different brightness in multi-stages.

Method of driving a display device

In a display device having a plurality of scanning-side electrodes arranged in one direction, a plurality of data-side electrodes arranged in a second direction intersection the first direction, and dielectric layers interposed therebetween, a modulated voltage the magnitude of which is varied according to the emission or non-emission of light is applied to the data-side electrodes, while applying a write voltage in line sequential fashion to the scanning-side electrodes, thereby performing the display control. In such a display device, the polarity of the voltage applied between the data-side electrode and the scanning-side electrode corresponding to the picture element to be driven for light emission is reversed one or more times during the period in which the write voltage is being applied to the scanning-side electrode. This serves to reduce the modulated voltage and the write voltage, thus contributing to the reduction in power consumption. Even when the modulated voltage or the write voltage is reduced, the desired brightness of emitted light can be obtained. In the case of not lowering the modulated voltage or the write voltage, it is possible to further enhance the brightness of emitted light.

Method and apparatus for driving a capacitive flat matrix display panel

A thin film EL display device is described which comprises a group of parallel scanning electrodes, a group of parallel data electrodes laid so as to extend perpendicular to the group of the scanning electrodes, and an EL layer disposed between the respective groups of the scanning and data electrodes. Each of the electrodes of at least one of the groups of the scanning and data electrodes which apply a writing voltage to the EL layer is connected with a driver circuit of high voltage breakdown characteristic having only a push-pull function or a pull-up and pull-down function. This driver circuit employs thyristors as switching elements.

Thin film el display device

A thin film EL display panel is composed of an EL layer placed between scanning electrodes and data side electrodes which are arranged at right angles to the scanning electrodes. A thin film EL display panel drive circuit includes a first and a second switching circuits connected to each of the scanning electrodes to apply voltages of negative and positive polarities, respectively, with respect to the voltage of the data side electrodes; and third and a fourth switching circuits connected to each of the data side electrodes to respectively charge and discharge the EL layer corresponding to the scanning electrode.

Thin film EL display panel drive circuit

A driving method of a thin film EL display unit and a driving circuit thereof comprising a thin film EL panel constituted by installing an EL layer between scanning-side electrodes and data-side electrodes and driver ICs which are connected respectively to the scanning-side electrodes and the data-side electrodes, wherein, on a drive which applies a write voltage positive to the data-side electrodes to the scanning-side electrodes, the scanning-side electrodes are raised once to a predetermined potential or higher, and thereafter the positive write voltage is applied thereto, and on a drive which applies a write voltage negative to the data-side electrodes to the scanning-side electrodes, the scanning-side electrodes are reduced once to a predetermined potential or lower, and thereafter the negative write voltage is applied thereto, which can reduce a maximum voltage applied to the scanning-side driver ICs.

Driving method of thin film EL display unit and driving circuit thereof

A thin-film EL display panel drive circuit capable of varying the drive voltage according to changes in the number of emitting picture elements.

A thin film electroluminescent (EL) display panel drive circuit includes first and second switching circuits for driving scanning electrodes of the panel in two fields, wherein odd numbered scanning electrodes are applied with a negative voltage polarity and even numbered scanning electrodes are provided with a positive voltage polarity in a first field, and the voltage polarities are reversed during the second field. Data signals are applied to data electrodes by a data electrode driver circuit which includes third and fourth switching circuits for providing selected data electrodes with a modulate voltage of a stepwise nature or ground, depending upon whether the selected data electrodes intersect with selected scanning electrodes having a negative or positive voltage polarity respectively. The stepwise modulation voltage is supplied by a control switching circuit which selectively supplies the third switching circuit with voltages of a first level, a second level and a floating level.

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Nara, Japan

Toshihiro Ohba