Sanyo Electric Co., Ltd.

Naoaki Komiya

Masahiro Okuyama

Tsutomu Yamada

Ryoichi Yokoyama

Ryuji Nishikawa

Shoichiro Matsumoto

Koji Hirosawa

Kiyoshi Yoneda

Keiichi Sano

Katsuya Anzai

Kiichi Hirano

An active matrix type electroluminescence display device is provided which comprises a plurality of display pixels GS, GS, GS, arranged in a matrix of rows and columns; gate signal lines GL, GL, Gli connected to and shared by a plurality of display pixels arranged in each row; and gate drive circuits for sequentially supplying a select signal SCAN to the gate signal lines GL, GL, GL, Gli. Each display pixel includes an electroluminescence element, a first thin film transistor in which a display signal DATA is applied to the drain and which is switched on and off in response to the select signal SCAN, and a second thin film transistor for driving the EL element based on the display signal DATA. The gate drive circuits are placed so that each of the gate signal lines GL, GL, GL, Gli is driven from both ends.

Active matrix type electroluminescence display device

An active matrix type electroluminescence display device comprises a plurality of display pixels GS, GS, GS, etc. arranged in a matrix of rows and columns, each display pixel including an EL element, a first thin film transistor in which a display signal is applied to the drain and which is switched on and off in response to a select signal, a capacitance with one end connected to the source of the first thin film transistor for maintaining a voltage corresponding to the display signal, and a second thin film transistor for driving the EL element based on the display signal. The other ends of the capacitance of row display pixels are connected to and shared by a plurality of first capacitance lines HLA, HLA, HLA, HLAi. Both ends of the plurality of first capacitance lines HLA, HLA, HLAare connected to and shared by second capacitance lines HLBand HLB. A constant voltage is supplied to the second capacitance line.

Power source lines () for supplying drive current from power source input terminals () to organic EL elements () formed in a display pixel region having display pixels are connected by a bypass line () along the row direction within the display pixel region. This arrangement minimizes decrease in power source current caused by resistance of the power source lines () according to the line length. Accordingly, the organic EL elements () can adequately receive the actual desired current, thereby achieving an organic EL device capable of bright displays and having uniform display luminance within the display region.

Emissive display device and electroluminescence display device with uniform luminance

A low power-consumption active matrix display device including gate lines, drain lines, and pixel electrodes, which are arranged at intersections between the gate lines and the drain lines. A drain line driver is connected to the drain lines to select a drain line and provide the selected drain line with an image signal. A gate line driver is connected to the gate lines to select a predetermined gate line and provide the selected gate line with a gate signal. Level shifters are connected to the drain line driver to operate in a time-dividing manner. Each level shifter supplies the drain line driver with a boosted voltage.

Active matrix display device

Using scan (TFT-&#x2dc;TFT-) data having a size of 3 bits from data lines (DATA&#x2dc;DATA) is stored in storage capacitors (SC&#x2dc;SC). Driving TFTs (TFT-&#x2dc;TFT-) are switched fully on by the voltage of these storage capacitors (SC&#x2dc;SC). The on/off conditions of the driving TFTs (TFT-&#x2dc;TFT-) are controlled according to digital data, to control the on/off conditions of organic EL elements (EL&#x2dc;EL) and provide brightness control.

Organic EL circuit

An insulator substrate () is provided with a display pixel region () comprising an electroluminescence element () having a cathode (), emissive layer (), and anode (), and with first and second TFTs for driving the element. Surrounding the display pixel region (), a peripheral drive circuit region () having a third TFT for driving each pixel is further provided on the insulator substrate (). The cathode () is disposed in a region other than the peripheral drive circuit region (). With this arrangement, generation of a back channel by applying the EL element potential to the cathode is prevented in a complementary TFT employed in the peripheral drive circuit region for controlling the display region, thereby suppressing changes in threshold values due to such back channel generation. As a result, an EL display device with reduced generation of penetration current and minimized increased current consumption is achieved.

Electroluminescence display device

A discharge transistor (TFT) which connects the upper end of an organic EL element (EL) and a negative power source (VEE) and a control transistor (TFT) which connects the upper end of a storage capacitor (SC) with a power source (PVDD) are provided. These transistors (TFTTFT) are turned on by the upper gate line, so that the capacitor of the organic EL element (EL) is discharged prior to the selection of the line for these transistors.

Organic EL pixel circuit

An EL element () having an organic emissive layer or the like between the anode and cathode is used as an element to be driven, and an element driving TFT () for controlling the current supplied to the EL element () and a compensation thin film transistor () having an opposite conductive characteristic as the element driving TFT () are provided between the EL element () and the power supply line VL. With this structure, variation in the current supplied to each EL element () is reduced.

Thin film transistor for supplying power to element to be driven

A wide line portion is drawn from a cathode while another wide line portion is formed by gathered lines extending from cathode terminals. A contact of realtively large size is formed in a region where the two wide line portions overlap each other with an insulating film being interposed therebetween, so as to connect both wide line portions. Further, in this contact, the cathode terminals and the cathode are connected through an intermediate layer composed of a conductive oxide material. Thus, a reduction in the voltage to be applied to the cathode as a result of increased line resistance between the terminals and the cathode can be prevented, thereby preventing deterioration of display quality.

Line structure in electroluminescence display device

Powder desiccant is mixed into a seal which adheres a first substrate to a second substrate, thereby sealing a display region. Almost no moisture permeates through the outer surfaces of the substrates sandwiching the display region, while moisture permeating through the seal is adsorbed by the desiccant. An emissive layer is thereby prevented from deterioration due to moisture. By covering the display region with a resin sealing layer composed of resin having desiccant mixed therein, the display region can reliably be protected from moisture. By forming a groove in the substrate and placing a desiccant therein, moisture can be further reliably adsorbed.

Electroluminescence display device having a desiccant

Between a positive power supply and a negative power supply , a p-channel transistor and an n-channel transistor are connected in series while a p-channel transistor and an n-channel transistor are also connected in series. An inverted input signal *Sig is input to the respective gates of the transistors and , while an input signal Sig is input to the respective gates of the transistors and . As a result, of a pair of the transistors connected in series, namely either the transistors and or the transistors and , when one transistor turns ON, the other transistor turns OFF. Thus, generation of through currents is prevented.

Level shifter for use in active matrix display apparatus

Power source lines ( ) for supplying drive current from power source input terminals ( ) to organic EL elements ( ) formed in a display pixel region having display pixels are connected by a bypass line ( ) along the row direction within the display pixel region. This arrangement minimizes decrease in power source current caused by resistance of the power source lines ( ) according to the line length. Accordingly, the organic EL elements ( ) can adequately receive the actual desired current, thereby achieving an organic EL device capable of bright displays and having uniform display luminance within the display region.

A current control circuit is provided between a power source circuit and a power source line VL which supplies a drive current to an organic EL element provided in each emissive pixel of a display panel. An amount of current flowing from the power source circuit to the power source line VL is detected, and when the amount of current increases, a power source voltage Vdd to be applied to the power source line VL is decreased, thereby decreasing a current flowing thorough the organic EL element. Alternatively, contrast or brightness level of display data to be supplied to each EL element is controlled in accordance with the detected amount of current, so that when the current amount increases, the contrast or brightness level is reduced thereby restricting a current flowing through the organic EL element. Thus, the amount of current flowing through the organic EL element can be restricted to thereby prevent excessive power consumption of the display device.

Display device having driven-by-current type emissive element

In a display device including, for each pixel, an organic EL element ( ) and TFTs ( ) for controlling the element, a sequential circuit ( ) is provided for stopping supply of power source voltages Vvdd and Hvdd to drivers ( ) for driving the TFTs ( ) which control each organic EL element ( ) after stopping supply of power source voltage Pvdd to the organic EL element ( ) when the device is turned off.

Display device

The emitted luminance of an EL device is controlled in an analog manner so as to realize a multiple gray-scale display by employing a first TFT ( ) for switching, which turns on and off according to a selection signal SCAN and a second TFT ( ) for driving an EL device ( ) having an emissive layer between a pair of electrodes, by providing an analog switch ( ) for sampling an analog video signal (VIDEO) at a predetermined period and a capacitor ( ) for holding a sampling voltage from the analog switch ( ), and by applying the analog voltage held in the capacitor ( ) to the gate of the second TFT.

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Kobe, Japan

Naoaki Komiya