Sharp Kabushiki Kaisha Corporation

Noritaka Kishi

Noboru Noguchi

Masanori Ohara

Shigetsugu Yamanaka

Hiroyuki Furukawa

Tamotsu Sakai

Kazuyoshi Yoshiyama

Katsuya Otoi

Kazuo Takizawa

Naoko Gotoh

Daichi Nishikawa

Naoko Goto

Katsuhiro Kikuchi

Hideki Uchida

Kaoru Yamamoto

Yasuyuki Ogawa

Satoshi Inoue

Yoshimitsu Yamauchi

Yuto Tsukamoto

Akira Tagawa

Kengo Takahama

Eiji Koike

Yoshifumi Ohta

Norikazu Okada

Hiromitsu Katsui

Keiko Higashi

An organic EL display device includes: a pixel circuit drive unit configured to drive pixel circuits while performing a property measuring process in which a property of circuit elements is measured; a parameter table configured to store parameter values derived from monitoring data obtained in the property measuring process; a compensation computation unit configured to correct externally provided image data based on the parameter values stored in the parameter table, so as to generate a digital video signal to be fed to the pixel circuits; a temperature sensor configured to sense temperature; and a monitoring control section configured to control an execution frequency of the property measuring process in accordance with the sensed temperature. The monitoring control section increases the execution frequency of the property measuring process with an increase in the sensed temperature.

Display device and driving method therefor

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

In a current measurement period set in a pause period, a display device of the present invention applies measurement voltages to data lines (Sto Sm) and measures currents outputted to monitoring lines (Mto Mm) from m pixel circuits (), and then applies data voltages generated corresponding to video signals to the data lines (Sto Sm).

Display device and method for driving same

In a data line drive/current measurement circuit, m measurement units are disposed in a plurality of semiconductor chips such that the m measurement units are distributed among the plurality of semiconductor chips. A display apparatus includes transistors such that one transistor is provided for two adjacent semiconductor chips. Inter-chip correction data indicating a variation among the semiconductor chips in terms of characteristics of elements in the measurement units is determined based on a result of a current measurement performed for the same transistor using measurement units disposed in different semiconductor chips. The inter-chip correction data is stored in a storage unit and is used in correcting an image signal. The inter-chip correction data may be determined based on a result of measuring a current flowing through a common cathode of organic EL elements for each semiconductor chip. Thus, a variation in the characteristic of the element among the semiconductor chips is compensated for and high image quality is achieved in displaying.

Display apparatus and driving method therefor

A display device that is configured to include two independent shift registers and is capable of performing a monitoring process without causing the degradation of display quality or the occurrence of abnormal operation is implemented. In a display device including: a writing control shift register composed of a plurality of first unit circuits () each including a first boost circuit () and a first output node reset circuit (); and a monitoring control shift register composed of a plurality of second unit circuits () each including a second boost circuit () and a second output node reset circuit (), current drive capability of the first boost circuit () is higher than current drive capability of the second boost circuit (), and current drive capability of the second output node reset circuit () is higher than current drive capability of the first output node reset circuit ().

Display device including output control circuits

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 detection/correction output circuit of a data-line driving circuit is provided with a transimpedance circuit including an operational amplifier and a current-detection transistor to detect a driving current that has passed through a driving transistor in a pixel circuit. The output voltage of the operational amplifier is amplified by using resistance elements connected in series. Thereby, it is possible to compensate the threshold voltage of the driving transistor with high accuracy by establishing a prescribed relationship between the gain of the driving transistor and the gain of the current detection transistor (by matching both gains) even if there is a difference between both gains. The output voltage of the operational amplifier may be amplified using a non-inverting amplifier circuit.

Display apparatus and driving method thereof

The organic EL display device includes: a current monitoring section that measures a current flowing in a circuit element and outputs a digital measured value in accordance with the measured current; and an averaging section () that calculates an average value of a plurality of input values. The current monitoring section measures the current flowing in a circuit element in each pixel circuit a plurality of times in a fixed amount of time. For each pixel circuit, the averaging section () receives a plurality of measured values outputted from the current monitoring section in a fixed amount of time as a plurality of input values and outputs an average value of the plurality of digital measured values as a value for use in compensation computation to compensate for degradation of the circuit element.

Display device and method of driving same

When a display mode is a high-resolution mode, image display is performed by time division driving. When the display mode is a low-resolution mode, image display is performed by defining j pixel circuits arranged continuously in a direction in which scanning signal lines extend as one group, bringing only one organic EL element into a light-emitting state in each of the pixel circuits in a frame period, and bringing organic EL elements having respective light emission colors different from one another into a light-emitting state in the j pixel circuits included in each group in the frame period. Pixel circuits in a display unit are configured such that the intervals of organic EL elements which go into a light-emitting state in the frame period when in the low-resolution mode are equalized regarding a direction in which the scanning signal lines extend.

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.

The purpose of the present invention is to suppress the fluctuation of a data line voltage that occurs when an analog voltage signal is sampled and held in a data line in a display device provided with a current-driven display element. Transistors (SWr, SWG, SWb) of each demultiplexer () are successively switched on, for each predetermined period, in a selection period of a write control line (SW_LR(i)). In a period when the transistor (SWr) is switched on, an analog video signal (Dj) from a data voltage output unit circuit () is applied to a data line (SLrj) and a pixel circuit (). When the transistor SWr is then switched off, the voltage held by the data line (SLrj) decreases below the voltage of the analog video signal (Dj) due to a parasitic capacitance (Cssdr). However, the voltage of a voltage fluctuation compensation line (G_Cnt (i)) changes from a low level to a high level within the selection period. This causes the voltage of the data line (SLrj) to rise via a capacitor (Ccnt), and the decrease in voltage to be compensated for.

Pixel circuit, display device, and method for driving same

An object of the present invention is to implement a display device capable of compensating for degradation of circuit elements without causing a grayscale failure. Based on the results of detection of characteristics of drive transistors and organic EL elements, a control circuit () finds magnitudes of threshold shifts of the drive transistors and the organic EL elements. A power supply voltage control unit () sets a value of a low-level power supply voltage (ELVSS) to a value lower, by a voltage value corresponding to an average value of the magnitudes of the threshold shifts for all pixels, than a value at an initial point in time. Furthermore, the power supply voltage control unit () adjusts a value of a high-level power supply voltage (ELVDD), depending on magnitudes of mobilities obtained by detection of characteristics of the drive transistors.

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.

Based on the results of detection of characteristics of drive transistors and organic EL elements, a control circuit finds magnitudes of threshold shifts of the drive transistors and the organic EL elements. A power supply voltage control unit sets a value of a low-level power supply voltage to a value lower, by a voltage value corresponding to an average value of the magnitudes of the threshold shifts for all pixels, than a value at an initial point in time. Furthermore, the power supply voltage control unit adjusts a value of a high-level power supply voltage, depending on magnitudes of mobilities obtained by detection of characteristics of the drive transistors.

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Osaka, Japan

Noritaka Kishi