Display device

• US 20040080500A1
• Filed: 10/20/2003
• Published: 04/29/2004
• Est. Priority Date: 10/21/2002
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Koyama, Jun
• Granted Patent: US 7,362,297 B2
• Time in Patent Office: Days
• US Class Current: 345/204
• CPC Class Codes: G09G 2330/022 in absence of operation, e.g. no data being entered during a predetermined time
• CPC Class Codes: G09G 2330/023 using energy recovery or conservation
• CPC Class Codes: G09G 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 5/18 Timing circuits for raster scan displays specially adapted for television H04N ; synchronisation between the display unit and other display units, videodisc player G09G5/12

Abstract

A display device of the present invention has an incorporated charge pump control circuit and a clock frequency of a switching element can be varied according to a display mode to reduce the power consumption. On the display device, a variable frequency-dividing circuit and a CPU to control the circuit are configured with thin film transistors. A clock frequency of a switching element is varied by controlling a dividing ratio of the variable frequency-dividing circuit on the basis of CPU data.

Claims

1. A display device comprising:

a charge pump control circuit comprising a thin film transistor on a substrate.

9. A display device according to claim 1, wherein the display device is a liquid crystal display device.

13. A display device according to claim 1, wherein the display device is an EL display device.

17. A display device according to claim 1, wherein the display device is applied to an electrical equipment selected from the group consisting of a digital camera, a notebook type personal computer, a PDA, a DVD playback device, a folding portable information device, a watch type display device and a mobile phone.

2. A display device comprising:

a charge pump control circuit comprising a thin film transistor on a substrate;

a switching element; and

a capacitor,

wherein the switching element is driven correspondingly to an output signal of the charge pump control circuit to step a voltage up or down.

3. A display device according to claim 2, wherein the charge pump control circuit can vary a clock frequency to input to the switching element.

4. A display device according to claim 3, wherein the frequency varying unit is controlled by a CPU.

5. A display device according to claim 4, wherein the CPU is comprised of a thin film transistor.

10. A display device according to claim 2, wherein the display device is a liquid crystal display device.

14. A display device according to claim 2, wherein the display device is an EL display device.

18. A display device according to claim 2, wherein the display device is applied to an electrical equipment selected from the group consisting of a digital camera, a notebook type personal computer, a PDA, a DVD playback device, a folding portable information device, a watch type display device and a mobile phone.

6. A display device comprising:

a variable frequency-dividing circuit comprising a thin film transistor; and

a CPU comprising a thin film transistor,

wherein the variable frequency-dividing circuit is controlled by the CPU, and

wherein a dividing ratio is varied according to a display mode.

11. A display device according to claim 6, wherein the display device is a liquid crystal display device.

15. A display device according to claim 6, wherein the display device is an EL display device.

19. A display device according to claim 6, wherein the display device is applied to an electrical equipment selected from the group consisting of a digital camera, a notebook type personal computer, a PDA, a DVD playback device, a folding portable information device, a watch type display device and a mobile phone.

7. A display device comprising:

a switching element comprising a PIN diode.

8. A display device according to claim 7, wherein the PIN diode is formed simultaneously with the thin film transistor.

12. A display device according to claim 7, wherein the display device is a liquid crystal display device.

16. A display device according to claim 7, wherein the display device is an EL display device.

20. A display device according to claim 7, wherein the display device is applied to an electrical equipment selected from the group consisting of a digital camera, a notebook type personal computer, a PDA, a DVD playback device, a folding portable information device, a watch type display device and a mobile phone.