Light emitting module and method of driving the same, and optical sensor

• US 7,068,246 B2
• Filed: 06/11/2001
• Issued: 06/27/2006
• Est. Priority Date: 06/12/2000
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Koyama, Jun, Yamazaki, Shunpei
• Primary Examiner(s): WU, XIAO MIN
• Application Number:
  US09/878,862
• Publication Number:
  US 20020027229A1
• Time in Patent Office: 1,842 Days
• Field of Search: 345/76, 345/77, 345/81, 345/82, 345/83, 345/87, 345/102, 345/207, 315/169.1, 315/169.3
• US Class Current: 345/76
• CPC Class Codes: G01J 1/4204 with determination of ambient light solar light G01J2001/4266
• CPC Class Codes: G01J 1/44 Electric circuits for command of an exposure part G03B7/02
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• 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 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 3/3275 Details of drivers for data electrodes
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• 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 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 27/1288 employing particular masking sequences or specially adapted masks, e.g. half-tone mask
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 : Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H10K 50/86 : Arrangements for improving contrast, e.g. preventing reflection of ambient light
• CPC Class Codes: H10K 59/13 : comprising photosensors that control luminance
• CPC Class Codes: H10K 59/8791 : Arrangements for improving contrast, e.g. preventing reflection of ambient light

Abstract

The object of the present invention is to provide a light emitting module which is excellent in visibility and can reduce power consumption.

The light emitting module includes a light emitting device containing at least a pixel section 101 and a sensor section 104, which are formed on the same insulating body, and further includes means for sensing illuminance of a use environment with the sensor section 104 and for adjusting luminance of a light emitting element according to the illuminance to keep a ratio of the luminance to the illuminance of the use environment at a constant value.

Claims

1. A light emitting module comprising:

a light emitting device comprising a pixel section and a sensor section which are formed on a same insulating body; and

a correction circuit connected to the light emitting device,

wherein said correction circuit adjusts luminance of a light emitting element of the pixel section according to environmental illuminance sensed by the sensor section and for keeping a ratio of the luminance to the environmental illuminance at a constant value by the correction circuit,

wherein said sensor section is disposed outside said pixel section, and

wherein said sensor section comprises at least one optical sensor comprising a photodiode, a reset TFT, a buffer TFT and a constant current TFT.

2. A light emitting module according to claim 1, wherein the sensor section includes a thin film photodiode.

3. A light emitting module according to claim 1, wherein the correction circuit comprises an arithmetic circuit for calculating the luminance of the light emitting element based on a signal transmitted from the sensor section.

4. A light emitting module according to claim 2, wherein the light emitting element and the thin film diode are electrically connected to a transistor.

5. A light emitting module according to claim 4, wherein the transistor is a bottom gate type thin film transistor.

6. A light emitting module according to claim 1, wherein the light emitting element is an EL element.

7. A light emitting module according to claim 1, wherein the light emitting module is included in one of a portable telephone, a video camera, a digital camera, a computer, and a portable telephone.

8. A light emitting module according to claim 1, wherein said sensor section comprises at least one optical sensor comprising a photodiode, a first reset TFT, a buffer TFT, a load capacitance, and a second reset TFT.

9. A light emitting module according to claim 1, wherein said sensor section comprises at least one optical sensor comprising a photodiode, a reset TFT, a buffer TFT, and a load resistance or a load capacitance.

10. A light emitting module according to claim 1, wherein said sensor section comprises at least one optical sensor comprising a photodiode and a reset TFT.

11. A light emitting module comprising:

a light emitting device comprising a pixel section and a sensor section sensing environmental illuminance which are formed on a same insulating body; and

a correction circuit connected to the light emitting device,

wherein the pixel section comprises a thin film light emitting element,

wherein the sensor section includes a thin film photodiode,

wherein the sensor section is disposed outside said pixel section, and

wherein said sensor section comprises at least one optical sensor comprising a photodiode, a reset TFT, a buffer TFT and a constant current TFT.

12. A light emitting module according to claim 11, wherein the correction circuit comprises an arithmetic circuit for calculating the luminance of the light emitting element based on a signal transmitted from the sensor section.

13. A light emitting module according to claim 11, wherein the light emitting element and the thin film photodiode are electrically connected to a transistor.

14. A light emitting module according to claim 13, the transistor is a bottom gate type thin film transistor.

15. A light emitting module according to claim 11, wherein the light emitting element is an EL element.

16. A light emitting module according to claim 11, wherein the light emitting module is included in one of a portable telephone, a video camera, a digital camera, a computer, and portable telephone.

17. A light emitting module according to claim 11, wherein said sensor section comprises at least one optical sensor comprising a photodiode, a first reset TFT, a buffer TFT, a load capacitance, and a second reset TFT.

18. A light emitting module according to claim 11, wherein said sensor section comprises at least one optical sensor comprising a photodiode, a reset TFT, a buffer TFT, and a load resistance or a load capacitance.

19. A light emitting module according to claim 11, wherein said sensor section comprises at least one optical sensor comprising a photodiode and a reset TFT.

20. A light emitting module comprising:

a light emitting device comprising a pixel section, a driving circuit, and a sensor section sensing environmental illuminance which are formed on a same insulating body; and

a correction circuit connected to the light emitting device,

wherein the pixel section includes a thin film light emitting element,

wherein the sensor section includes a thin film photodiode,

wherein said sensor section is disposed outside said pixel section, and

wherein said sensor section comprises at least one optical sensor comprising a photodiode, a reset TFT, a buffer TFT and a constant current TFT.

21. A light emitting module according to claim 20, wherein the correction circuit comprises an arithmetic circuit for calculating the luminance of the light emitting element based on a signal transmitted from the sensor section.

22. A light emitting module according to claim 20, wherein the light emitting element and the thin film photodiode are electrically connected to a transistor.

23. A light emitting module according to claim 22, wherein the transistor is a bottom gate type thin film transistor.

24. A light emitting module according to claim 20, wherein the light emitting element is an EL element.

25. A light emitting module according to claim 20, wherein the light emitting module is included in one of a portable telephone, a video camera, a digital camera, a computer, and a portable telephone.

26. A light emitting module according to claim 20, wherein said sensor section comprises at least one optical sensor comprising a photodiode, a first reset TFT, a buffer TFT, a load capacitance, and a second reset TFT.

27. A light emitting module according to claim 20, wherein said sensor section comprises at least one optical sensor comprising a photodiode, a reset TFT, a buffer TFT, and a load resistance or a load capacitance.

28. A light emitting module according to claim 20, wherein said sensor section comprises at least one optical sensor comprising a photodiode and a reset TFT.

29. A method for driving a light emitting module which comprises a light emitting device comprising a pixel section and a sensor section disposed outside said pixel section which are formed on a same insulating body and a correction circuit connected to the light emitting device, said method comprising the steps of:

adjusting luminance of the light emitting element of the pixel section according to environmental illuminance sensed by the sensor section; and

keeping a ratio of the luminance to the environmental illuminance at a constant value by correction circuit,

wherein said sensor section comprises at least one optical sensor comprising a photodiode, a reset TFT, a buffer TFT and a constant current TFT.

30. An electronic device comprising at least one electro luminescence display device, said display device comprising:

a substrate;

at least one pixel comprising an electro luminescence element over said substrate;

at least one first thin film transistor disposed at said pixel for selecting said pixel;

at least one second thin film transistor disposed at said pixel for supplying an electric current through said electro luminescence element;

a data signal side driver circuit for supplying a data signal to said pixel;

a gate signal side driver circuit electrically connected to a gate electrode of said first thin film transistor, wherein each of said data signal side driver circuit and said gate signal side driver circuit comprises third thin film transistors formed over said substrate; and

a sensor section for sensing a light intensity of an environment formed outside said pixel over said substrate, wherein said sensor comprises a photodiode and at least one fourth thin film transistor;

a correction circuit for receiving an output signal form said sensor section and correcting luminance of said electro luminescence element in accordance with said output signal.

31. An electronic device according to claim 30, wherein said correction circuit is provided over said substrate.

32. An electronic device according to claim 30 wherein said electric device is one of a portable telephone, a video camera, a digital camera, a computer, and portable telephone.

33. An electronic device comprising:

a substrate;

at least one pixel comprising an electro luminescence element over said substrate;

at least one first thin film transistor disposed at said pixel for selecting said pixel;

at least one second thin film transistor disposed at said pixel for supplying an electric current through said electro luminescence element;

at least one third thin film transistor disposed at least one driver circuit over said substrate;

at least one fourth thin film transistor disposed at a sensor section over said substrate;

a first insulating layer over said first thin film transistor, said second thin film transistor, said third thin film transistor and said fourth thin film transistor;

a second insulating layer over said first insulating layer; and

a photodiode electrically connected with said fourth thin film transistor through said first insulating layer and said second insulating layer, and disposed at said sensor section over said second insulating layer,

wherein said sensor section senses environmental illuminance.

34. A electronic device according to claim 33 further comprising a correction circuit over said substrate.

35. An electronic device comprising:

a substrate;

at least one pixel comprising an electro luminescence element over said substrate;

at least one first thin film transistor disposed at said pixel for selecting said pixel;

at least one second thin film transistor disposed at said pixel for supplying an electric current through said electro luminescence element;

at least one third thin film transistor disposed at least one driver circuit over said substrate;

at least one fourth thin film transistor disposed at a sensor section over said substrate;

a first insulating layer over said first thin film transistor, said second thin film transistor, said third thin film transistor and said fourth thin film transistor;

a photodiode electrically connected with said fourth thin film transistor through said first insulating film, disposed at said sensor section over said first insulating layer; and

a second insulating layer over said photodiode,

wherein said sensor section senses environmental illuminance.

36. A electronic device according to claim 35 further comprising a correction circuit over said substrate.