Global Oled Technology LLC

Eastman-kodak Company

Other

Semiconductor Manufacturing International (shanghai) Corporation

Makoto Kohno

Seiichi Mizukoshi

Kouichi Onomura

Nobuyuki Mori

Nobuyki Mori

Kazuyoshi Kawabe

An object of the invention is to convert input RGB data to R'G&#x2032;B&#x2032;W data without suffering loss of gradations of the input RGB data. A display panelis configured having unit pixels made up of subpixels of RGBW (red, green, blue, white). In an RGB&#x2192;R&#x2032;G&#x2032;B&#x2032;W conversion section, conversion is carried out under conditions that usage rate of W is less than 100%, and a bit width of input RGB data us larger than a bit width of R&#x2032;G&#x2032;B&#x2032;W data after conversion. In the RGB&#x2192;R&#x2032;G&#x2032;B&#x2032;W conversion section, R1G1B1values and W values are determined so that an absolute value of a sum of values obtained by multiplying differences between respective RGB data input and respective RGB components in R&#x2032;G&#x2032;B&#x2032;W data after conversion by a weight, becomes minimum.

Display device

The rate of reading from a memory for storing display irregularity correction data is lowered. At the time of display, calculation is carried out in a correction calculation section using an input signal and correction data in one or more memory units, and brightness inconsistency correction is carried out. The way in which correction calculation is carried out in the correction calculation section is changed for every frame.

To alleviate an afterimage phenomenon caused by a hysteresis characteristic of a drive transistor. Current driven type light emitting elementsare provided for each of pixelsthat are arranged in a matrix shape, and current of the light emitting elementsis controlled using drive TFTsthat operate by receiving data voltage on a gate. At least two power supply voltages (PVDDa, PVDDb) for supply to each pixel are provided, one being set to a voltage such that current corresponding to a data voltage flows in the drive TFT, the other being set to a voltage beyond a variation range of data voltage and that reverse biases the drive TFT, and the two power supply voltages are switched and supplied to each pixel

The rate of reading from a memory for storing display irregularity correction data is lowered. At the time of display, calculation is carried out in a correction calculation sectionusing an input signal and correction data in RAM, and brightness inconsistency correction is carried out. The way in which correction calculation is carried out in the correction calculation sectionis changed for every frame.

There is provided a display device in which disadvantageous effects due to unnecessary operations of an image lag alleviating function are minimized. In a display device of active matrix type, for each of the pixels arranged in a matrix, a current-driven emissive element is provided, and the current of the emissive element is controlled using a drive TFT so as to perform display. While a black display period during which an opposite bias voltage is applied between the gate electrode and the source electrode of the drive TFT is inserted in order to alleviate image lag, this insertion is performed only when a predetermined condition is satisfied, and is performed for a certain duration according to a command by a microcomputer ().

Display unevenness is suppressed. A display device includes pixels () arranged in matrix, each including a current-driven type light emitting element (EL) and a drive transistor (Tr) for supplying a current to the current-driven type light emitting element (EL). The current-driven type light emitting element (EL) is driven by dividing each frame period into a plurality of sub-frame periods for lighting time. The drive transistor is controlled under current write driving using two write currents having a ratio of 1:1/2and a sum of the two write currents.

To compensate for voltage drop on a power supply line. In a display device, pixel data is supplied to each of a plurality of pixels arranged in a matrix form and display is performed. Each pixel has a self-emissive element. A horizontal direction power supply line (horizontal direction PVDD) which supplies a power supply to each pixel is provided, and one end of the horizontal PVDD line is connected to a vertical power supply line (vertical PVDD line) that is connected to an external power supply terminal. Correction data corresponding to a voltage drop to the horizontal PVDD line due to a resistance in the vertical PVDD line is then obtained through a calculation based on pixel data, and the input pixel data is corrected using the correction data so as to reduce the influence of the voltage drop on the pixel current.

Compensating voltage drop for display device

In order to maintain a high visual image quality and save power, a display device includes: R sub-pixels, G sub-pixels, B sub-pixels, and W sub-pixels; and a human detection sensor () for detecting whether or not a person is present within a predetermined range. A use rate of the W sub-pixels is changed depending on whether or not a person is present within the predetermined range.

Nonuniformity in an organic EL display device is effectively detected. All display pixels of an organic EL panel are turned on and the display is photographed with a digital camera. A computer performs image processing of the photographed image to detect an area in which unevenness exists. Then, a V-I curve of each pixel in the area is measured to calculate necessary correction values. The calculated correction values are stored in a memory for use in correcting a signal input to the organic EL panel.

Method of correcting nonuniformity of pixels in an OLED

Noise on a current to be measured is removed. Horizontal power supply lines (PVDD) are arranged in a horizontal direction and supply a current to pixels in respective corresponding horizontal lines. A switch () connects a group of the horizontal power supply lines (PVDD) to a first power supply line (PVDDa) or a second power supply line (PVDDb) disposed outside a pixel region in a switchable manner. Only the horizontal power supply lines (PVDD) in a group to which a pixel to be measured belongs are supplied with power from the second power supply line (PVDDb) so as to measure a current of each pixel in the group, and a current flowing into a power source (PVDDa) connected to a group to which other pixels than the pixel to be measured belong is measured, to thereby calculate a pixel current based on a difference between the two measured currents.

A driving method of a display device in which an image is displayed on a display panel having a display element arranged in a pixel matrix, includes comparing, among pixel data corresponding to a display content in each pixel, pixel data corresponding to an nth horizontal scan line of an Nth frame and pixel data corresponding to an nth horizontal scan line of an (N&#x2212;1)th frame; and setting a brightness reduction ratio with respect to pixel data corresponding to the nth horizontal scan line of the Nth frame or a later horizontal scan line of the Nth frame based as a function of the comparison and all pixel data corresponding to the (N&#x2212;1)th frame or all pixel data from the nth horizontal scan line of the (N&#x2212;1)th frame to an (n&#x2212;1)th horizontal scan line of the Nth frame and controlling power supplied.

Driving device and driving method for display device

A method of measuring a panel current in an active matrix organic electroluminescence display panel, wherein when a current flowing through a display panel when one or a plurality of pixels are caused to emit light is measured, a flow-in current flowing into the display panel from a side of a high voltage and a flow-out current flowing out from the display panel toward a side of a low voltage are simultaneously measured, and a value of a panel current is determined using both obtained measurement results.

Method and device for measuring panel current

An electroluminescent display device having a first and a second power supply; a respective power supply line for each row, wherein each power supply line is placed along a horizontal direction and is connected to the respective first electrodes of the driving TFTs of the pixels in the corresponding row; a plurality of switches, each connected to one or more power supply lines, for selectively connecting the corresponding one or more power supply lines to either the first or the second power supply; a gate driver for selecting a gate line; and a selecting circuit for controlling the plurality of switches, wherein the selecting circuit causes the power supply line corresponding to the selected gate line to be connected to the first power supply, and the one or more power supply lines not corresponding to the selected gate line to be connected to the second power supply.

Current controlled electroluminescent display device

An OLED display having a correction circuit for producing corrected image data in response to the first image data and in response to correction data to correct for brightness unevenness due to TFT variations; a memory for storing first image data or correction data; a switch effective in first and second states in response to a function switching signal having first and second conditions, respectively; and circuitry for causing the switch to be in the first state to connect the memory to the image input signal interface and to provide the stored first image data to the panel as the second image data; and for causing the switch to be in the second state to connect the memory to the correction circuit, provide the stored correction data to the correction circuit, and provide the corrected image data to the panel as the second image data.

Correcting brightness variations in organic electroluminescent panel

During image display, pixel current measurement for brightness irregularity correction is carried out. Display is carried out by sequentially writing pixel data in a horizontal direction to pixel sections that are arranged in a matrix shape. Horizontal power supply lines PVDD are arranged for each horizontal line, and power is supplied from these power supply lines to corresponding pixel sections. When carrying out measurement of pixel current by lighting pixel sections one at a time, a horizontal power supply line PVDD of a horizontal line to which the lit pixel belongs is connected to a power supply PVDDb by a switch, and other horizontal power supply lines PVDD are connected to PVDDa.

Growing community of inventors

Kanagawa, Japan

Makoto Kohno