Organic EL panel

• US 20050073264A1
• Filed: 09/27/2004
• Published: 04/07/2005
• Est. Priority Date: 09/29/2003
• Status: Active Grant

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Matsumoto, Shoichiro
• Granted Patent: US 7,102,293 B2
• Time in Patent Office: Days
• US Class Current: 315/169.300
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/351 comprising more than three subpixels, e.g. red-green-blue-white [RGBW]

Abstract

A drive transistor is connected, via its drain region, to a power supply line, and, via its source region, to a transparent electrode of an organic EL element. The channel region is formed bent into a substantially L shape. This arrangement is able to simplify the arrangement of a gate electrode by providing the gate electrode so as to run straight over a channel region in parallel to the power source line. Accordingly, the aperture ratio is increased.

Claims

1. An organic EL panel where pixels are arranged in matrix, each pixel including an organic EL element having at least an organic light emitting layer between a pair of electrodes,

wherein

each pixel has a drive transistor for supplying a current from a power supply line to the organic EL element of the pixel,

the drive transistor has a semiconductor layer having a substantially L shape,

a source region and a drain region are formed at both ends of the semiconductor layer, and

a portion of the semiconductor layer between the source region and the drain region is covered by a gate electrode which extends straight along one edge of the semiconductor layer having the substantially L shape.

2. The organic EL panel according to claim 1, wherein the power supply line extends in a column direction, and the semiconductor layer comprises a first portion extending along the power supply line and a second portion bending at a substantially right angle.

3. The organic EL panel according to claim 2, wherein the gate electrode extends in a direction identical to a direction in which the first portion extends.

4. The organic EL panel according to claim 2, wherein a tip end of the first portion is connected to the power supply line, and the second portion is connected to the organic EL element.

5. The organic EL panel according to claim 4, wherein the power supply line has a projected portion projecting toward a side of the drive transistor, and the projected portion is connected to the first portion via a contact.

6. The organic EL panel according to claim 1, wherein the power supply line is placed between columns of the pixels and supplies power to the organic EL elements of the pixels in two columns arranged on both sides of the power supply line.

7. The organic EL panel according to claim 6, wherein

light emitting colors of the pixels include R (red), G (green), B (blue), and W (white),

pixels for emitting light of the same color are arranged in a column direction,

one of the power supply lines is shared by pixels in a column for a light color with maximum current efficiency in light emission by the organic EL element and pixels in a column for a light color with minimum current efficiency, and

another power supply line is shared by pixels in columns for other light colors.

8. The organic EL panel according to claim 7, wherein the one of the power supply lines is shared by pixels for W and G light, and the other power supply line is shared by pixels for W and G light.

9. The organic EL panel according to claim 1, wherein

each pixel has a holding capacitor for holding a gate voltage of the drive transistor,

the holding capacitor is placed on a side of one end of each pixel in the column direction,

the organic EL element is placed on a side of another end of the pixel in the column direction, and

the drive transistor is placed between the organic EL element and the power supply line.

10. The organic EL panel according to claim 9, wherein the power supply line has a projected portion projecting toward a side of the pixel, and the projected portion is connected to the drive transistor.