Driving method of a display device employing electro-light-emitting elements and the same display device

• US 6,222,323 B1
• Filed: 11/08/1999
• Issued: 04/24/2001
• Est. Priority Date: 11/06/1998
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Yamashita, Hideaki, Yamashita, Akihiro
• Primary Examiner(s): Philogene, Haissa
• Application Number:
  US09/436,466
• Time in Patent Office: 533 Days
• Field of Search: 315/169.3, 315/167, 315/168, 315/169.1, 315/169.2, 315/149, 315/163, 345/44, 345/48, 345/55, 345/76, 345/77, 345/68, 345/84, 345/90, 313/504-506
• US Class Current: 315/169.3
• CPC Class Codes: G09G 2310/0213 controlling the sequence of the scanning lines with respect to the patterns to be displayed, e.g. to save power
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2330/023 using energy recovery or conservation
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3216 using a passive matrix

Abstract

A driving method of a display device which includes cathodes formed by plural stripe-lines and anodes across the cathodes and formed by plural stripe-lines as well as a light-emitting layer provided between the cathodes and anodes. Firstly, illuminate a first light-emitting element connected to a first cathode, secondly, in order to illuminate a second light-emitting element connected to a second cathode, run electric current into the second element. In this case, remove part of stored charges in the second element and leave charges in at least one light-emitting element other than the second element, then run electric current into the second element. This driving method allows the display device to reduce the power consumption.

Claims

1. A method of driving a display device, said method comprising the steps of:

(a) providing the display device, wherein said display device includes a plurality of

cathodes,

anodes facing the cathodes, and

a plurality of emitting elements having an organic emitting layer disposed between the cathodes and the anodes;

(b) applying a direct current to the organic emitting layer;

(c) illuminating a first light-emitting element coupled to a first cathode;

(d) removing electric charges stored in a second light-emitting element and leaving electric charges in at least one of the light-emitting elements except the second light-emitting element; and

(e) running electric current through the second light-emitting element.

2. A method of driving a display device, said method comprising the steps of:

(a) providing the display device, wherein said display device includes a plurality of light-emitting elements which include cathodes including a plurality of stripe lines, anodes across the cathodes and having a plurality of strip lines, and a light-emitting layer between the cathodes and the anodes;

(b) detecting light in an environment where the display device is used; and

(c) controlling electric current running through the light-emitting layer responsive to the light detected.

3. The method of driving a display device as defined in claim 2 wherein the electric current running through the light-emitting layer is controlled by varying a period during which the current runs.

4. A method of driving a display device, said method comprising the steps of:

(a) providing the display device, wherein said display device includes a plurality of

cathodes,

anodes facing the cathodes,

and a plurality of emitting elements having an organic emitting layer disposed between the cathodes and the anodes;

(b) applying a direct current to the organic emitting layer;

(c) setting a luminance level responsive to a time signal sent from a clock; and

(d) controlling a current running through the emitting layer responsive to the luminance level.

5. The method of driving a display device as defined in claim 4 wherein the electric current running through the light-emitting layer is controlled by varying a period during which the current runs.

6. A display device comprising:

(a) a plurality of light-emitting elements including;

cathodes comprising a plurality of stripe lines;

anodes across said cathodes and comprising a plurality of stripe lines; and

a light-emitting layer provided between said cathodes and said anodes,

(b) an anode controller including;

electric current sources;

a first point having a given potential; and

a plurality of first switches for opening and closing between said anodes and one of said electric current sources and said first point; and

(c) a cathode controller including;

a voltage source;

a second point having a given potential; and

a plurality of second switches for opening and closing between said cathodes and one of said voltage source and said second point,

wherein said cathode controller applies a voltage to said cathodes sequentially as well as said anode controller supplies electric current to desirable said anodes for illuminating said light-emitting elements at intersections of said cathodes receiving a voltage and said desirable anodes,

wherein said display device illuminates a first light-emitting element coupled to a first cathode by running electric current through said first element, and for illuminating a second light-emitting element coupled to a second cathode, said first and said second switches—

both coupled to the second element—

are closed to said first and said second points respectively, and at the same time, anodes coupled to said light-emitting elements other than the second element are opened to both of said current sources and said first point, before electric current runs into said second element.

7. A display device comprising:

(a) a plurality of light-emitting elements including;

cathodes comprising a plurality of stripe lines;

anodes across said cathodes and comprising a plurality of stripe lines; and

a light-emitting layer provided between said cathodes and said anodes,

(b) an anode controller including;

electric current sources;

a first point having a given potential; and

a plurality of first switches for opening and closing between said anodes and one of said electric current sources and said first point;

(c) a cathode controller including;

a voltage source;

a second point having a given potential; and

a plurality of second switches for opening and closing between said cathodes and one of said voltage source and said second point,

(d) a brightness setter for determining a brightness level of said light-emitting elements based on external information; and

(e) a controller for controlling electric current running through said light-emitting elements based on the determined brightness level,

wherein said cathode controller applies a voltage to said cathodes sequentially as well as said anode controller supplies electric current to desirable said anodes for illuminating said light-emitting elements at intersections of said cathodes receiving a voltage and said desirable anodes, and

wherein, based on the determined brightness level, said controller controls said anode controller for adjusting electric current running through said light-emitting elements.

8. The display device as defined in claim 7 wherein the external information is sent from a photo-sensor.

9. The display device as defined in claim 7 wherein the external information is sent from at least one of a clock and a calendar.

10. The display device as defined in claim 7 further comprising an input section through which desirable information is supplied, wherein the brightness level of the light-emitting elements is determined based on the information.

11. A display device comprising:

(a) a plurality of emitting elements including;

(a-1) a plurality of cathodes;

(a-2) anodes facing said cathodes;

(a-3) an emitting layer disposed between said cathodes and said anodes;

(b) a current source for supplying an electric current to selected members of said emitting elements;

(c) a luminance setter for setting a luminance level of said emitting elements based on external information; and

(d) a controller for controlling a current running through said emitting elements.

12. The display device as defined in claim 11, wherein the external information is from an optical sensor.

13. The display device as defined in claim 11, wherein the external information is from at least one of a clock and a calendar.

14. The display device as defined in claim 11 further comprising an input section for receiving desirable information input by a user, so that the luminance level of said emitting elements is set based on the desirable information.