Sharp Kabushiki Kaisha Corporation

Naoko Gotoh

Noritaka Kishi

Hiroyuki Furukawa

Tamotsu Sakai

Kazuyoshi Yoshiyama

Katsuya Otoi

Katsuhiro Kikuchi

Hideki Uchida

Kazuo Takizawa

An organic EL panelis a bendable display panel including a plurality of pixel circuitseach having a light emitting element and a drive element. A data line drive circuitperforms, by driving data lines, an operation of writing a voltage to a control terminal of the drive element and an operation of measuring a current flowing through the drive element for the pixel circuitsselected by a scanning line drive circuit. A bending detection unitdetects a bending state of the organic EL panelbased on a measurement result of the current flowing through the drive element. A correction unitcorrects a video signal VSbased on the detected bending state. With this, the bending state of a screen is detected and a change in brightness or color when the screen is bent is prevented.

Flexible display device and method for detecting bending state thereof

A measurement circuit includes a plurality of measurement units, performs, at a same timing, a main measurement for measuring a current or a voltage with respect to a pixel circuit with supplying a measurement voltage to a part of the measurement units and a dummy measurement for measuring a current or a voltage with supplying a dummy signal to remaining measurement units, and performs a calculation on a result of the main measurement and a result of the dummy measurement. As the dummy signal, a signal with which a value to be measured is approximately zero is used. The measurement result of the current or the voltage is used for correcting a video signal. With this, a display device which can remove noise in measurement when measuring the current or the voltage with respect to the pixel circuit is provided.

Display device and drive method therefor

A current measurement circuit measures a current flowing through a drive transistor when a plurality of measurement voltages are written to a pixel circuit in a switching manner, and a current flowing through an organic EL element when another plurality of measurement voltages are written to the pixel circuit in a switching manner. A correction unit obtains a threshold voltage and a gain of the drive transistor and the organic EL element with respect to each pixel circuit based on a measured current, determines in which operation region the drive transistor operates between a saturation region and a triode region with respect to each pixel circuit based on the video signal, and corrects the video signal in accordance with the operation region of the drive transistor. Since the drive transistor operates both in the saturation region and the triode region, it is possible to reduce a power supply voltage and reduce power consumption of a display device.

In a current measurement period of a pixel circuit (), a measurement voltage is applied to a non-inverting input terminal of an operational amplifier (), switches () turn on, and a switch () turns off. Next, the switch () turns off, and a capacitor () is charged with charge of a current flowing through the pixel circuit (). Next, the switch () turns off, the switch () turns on, a constant current flows through a current source (), and a voltage of a second terminal (terminal connected to an output terminal of the operational amplifier ()) of the capacitor () decreases. A voltage comparator () and a counter () measure the current flowing through the pixel circuit () by measuring time until a voltage of the second terminal of the capacitor reaches a voltage Vcomp. A video signal VSis corrected based on a current measurement result. With this, it is possible to compensate for capacitance variation of a capacitance in a current measurement circuit and perform high image quality display.

Growing community of inventors

Sakai, Japan

Naoko Gotoh