Display system and electrical appliance

• US 7,688,290 B2
• Filed: 01/03/2001
• Issued: 03/30/2010
• Est. Priority Date: 01/17/2000
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Koyama, Jun, Yamazaki, Shunpei, Shibata, Noriko
• Primary Examiner(s): Kumar; Srilakshmi K
• Application Number:
  US09/752,817
• Publication Number:
  US 20010020922A1
• Time in Patent Office: 3,373 Days
• Field of Search: 345 44- 46, 345/77, 345/102, 345/690, 345/207, 345/82, 345/80, 345/81, 345 30-111, 345/76, 348/602, 348/603, 348/687, 250/205, 315/169.3, 257/763, 340281-282
• US Class Current: 345/77
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• 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 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/028 Generation of voltages supplied to electrode drivers in a matrix display other than LCD
• CPC Class Codes: G09G 2354/00 Aspects of interface with display user
• CPC Class Codes: G09G 2360/14 Detecting light within display terminals, e.g. using a single or a plurality of photosensors
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/30 using electroluminescent panels
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 5/10 Intensity circuits

Abstract

A display system in which the luminance of light-emitting elements in a light-emitting device is adjusted based on information on an environment. A sensor obtains information on an environment as an electrical signal. A CPU converts, based on comparison data set in advance, the information signal into a correction signal for correcting the luminance of EL elements. Upon receiving this correction signal, a voltage changer applies a predetermined corrected potential to the EL elements. Thus, this display system enables control of the luminance of the EL elements.

Claims

1. A display system comprising:

a plurality of pixels, each of said plurality of pixels comprising at least a transistor and an EL (electro-luminescent) element having a first electrode and a second electrode;

a sensor for obtaining an information signal of an environment;

a CPU (central processing unit) for converting said information signal of the environment supplied from said sensor into a correction signal;

an EL driving power source; and

a voltage changer connected to receive the correction signal and an output of the EL driving power source, and configured to produce an output potential that varies based on the correction signal,

wherein the output potential of the voltage changer is electrically connected to the second electrode of the EL element via a switch,

wherein the first electrode of the EL element is electrically connected to a power supply line via the transistor of the pixel including the EL element, and

wherein the switch is provided external to the pixels.

2. A display system according to claim 1, wherein said information signal comprises a user'"'"'s living-body information.

3. A display system according to claim 1, wherein said plurality of pixels, said sensor, said CPU and said voltage changer are formed on a same substrate.

4. A display system according to claim 1, wherein said EL (electro-luminescent) element comprises an organic material or an inorganic material.

5. A display system according to claim 1, wherein said display system is incorporated in one selected from the group consisting of a video camera, a digital camera, a head-mount display, a car navigation system, a portable telephone, an image reproduction apparatus, a car audio equipment, and a personal computer.

6. A display system according to claim 1, wherein the sensor comprises a CCD (charge-coupled device) or a photo-diode.

7. A display system according to claim 1, wherein the transistor is a current controlling thin film transistor.

8. A display system according to claim 1, further comprising:

a switching thin film transistor electrically connected to a gate electrode of the transistor of the pixel.

9. A display system according to claim 1, wherein the transistor of the pixel comprises a monocrystalline semiconductor film.

10. A display system comprising:

a plurality of pixels, each of said plurality of pixels comprising at least an EL (electro-luminescent) element having two electrodes with an EL layer interposed therebetween and a current control thin film transistor electrically connected to one of said two electrodes of said EL element;

an EL driving power source; and

a voltage changer connected to receive an information signal of an environment and an output of the EL driving power source, and to produce an output potential electrically connected to the other of said two electrodes of said EL element via a switch, wherein the voltage changer is configured to vary the output potential based on the information signal, and

wherein the switch is provided external to the pixels.

11. A display system according to claim 10, wherein said information signal comprises a user'"'"'s living-body information.

12. A display system according to claim 10, wherein said display system is incorporated in one selected from the group consisting of a video camera, a digital camera, a head-mount display, a car navigation system, a portable telephone, an image reproduction apparatus, a car audio equipment, and a personal computer.

13. A display system according to claim 10, wherein the EL (electro-luminescent) element comprises an organic material or an inorganic material.

14. A display system according to claim 10, further comprising:

a switching thin film transistor electrically connected to a gate electrode of the current control thin film transistor.

15. A display system according to claim 10, wherein the current control thin film transistor comprises a monocrystalline semiconductor film.

16. An active matrix display device comprising:

a sensor for obtaining an information signal of an environment;

a voltage changer connected to receive an output of an EL driving power source and a corrected potential generated by converting the information signal, and to generate an output potential that varies based on the corrected potential; and

a plurality of pixels, each of said plurality of pixels comprising;

at least one thin film transistor over a substrate, said thin film transistor comprising at least an active layer, and a gate electrode adjacent to said active layer with a gate insulating film interposed therebetween; and

an EL (electro-luminescent) element comprising at least an EL layer between an anode and a cathode, one of said anode and said cathode being electrically connected to said active layer,

wherein the output potential of the voltage changer is electrically connected to the other of the anode and the cathode of said EL element via a switch, and

wherein the switch is provided external to the pixels.

17. An active matrix display device according to claim 16, wherein said plurality of pixels and said sensor are formed over a same substrate.

18. An active matrix display device according to claim 16, wherein said sensor comprises a CCD (charge-coupled device) or a photo-diode.

19. An active matrix display device according to claim 16, wherein said information signal comprises a user'"'"'s living-body information.

20. An active matrix display device according to claim 16, wherein said display device is incorporated in at least one selected from the group consisting of a video camera, a digital camera, a head-mount display, a car navigation system, a portable telephone, an image reproduction apparatus, a car audio equipment, and a personal computer.

21. An active matrix display device according to claim 16, wherein the EL (electro-luminescent) element comprises an organic material or an inorganic material.

22. An active matrix display device according to claim 16, wherein the transistor is a current controlling thin film transistor.

23. An active matrix display device according to claim 16, further comprising:

a switching thin film transistor electrically connected to a gate electrode of the transistor.

24. An active matrix display device according to claim 16, wherein the active layer of the thin film transistor compnses a monocrystalline semiconductor film.

25. An active matrix display device comprising:

a sensor for obtaining an information signal of an environment;

a voltage changer connected to receive the information signal and an output of an EL driving power source, and to generate an output potential that varies based on the information signal; and

a plurality of pixels, each of said plurality of pixels comprising;

at least one thin film transistor over a substrate, said thin film transistor comprising at least an active layer, and a gate electrode adjacent to said active layer with a gate insulating film interposed therebetween; and

an EL (electro-luminescent) element comprising at least an EL layer between an anode and a cathode, one of said anode and said cathode being electrically connected to said active layer,

wherein the output potential of the voltage changer is electrically connected to the other of the anode and the cathode of said EL element via a switch, and

wherein the switch is provided external to the pixels.

26. An active matrix display device according to claim 25, wherein said plurality of pixels and said sensor are formed over a same substrate.

27. An active matrix display device according to claim 25, wherein said sensor comprises a CCD (charge-coupled device) or a photo-diode.

28. An active matrix display device according to claim 25, wherein said information signal comprises a user'"'"'s living-body information.

29. An active matrix display device according to claim 25, wherein said display device is incorporated in at least one selected from the group consisting of a video camera, a digital camera, a head-mount display, a car navigation system, a portable telephone, an image reproduction apparatus, a car audio equipment, and a personal computer.

30. An active matrix display device according to claim 25, wherein the EL (electro-luminescent) element comprises an organic material or an inorganic material.

31. An active matrix display device according to claim 25, wherein the transistor is a current controlling thin film transistor.

32. An active matrix display device according to claim 25, further comprising:

a switching thin film transistor electrically connected to a gate electrode of the transistor.

33. An active matrix display device according to claim 25, wherein the active layer of the thin film transistor comprises a monocrystalline semiconductor film.

40. An active matrix display device according to claim 25, wherein the EL (electro-luminescent) element comprises an organic material or an inorganic material.

34. An active matrix display device comprising:

a sensor for obtaining an information signal of an environment;

a CPU (central processing unit) for converting said information signal to a corrected signal;

a voltage changer connected to receive the corrected signal and an output of an EL driving power source, and configured to produce an output potential that varies based on the corrected signal; and

a plurality of pixels, each of said plurality of pixels comprising;

at least one thin film transistor over a substrate, said thin film transistor comprising at least an active layer, and a gate electrode adjacent to said active layer with a gate insulating film interposed therebetween; and

an EL (electro-luminescent) element comprising at least an EL layer between an anode and a cathode, one of said anode and said cathode being electrically connected to said active layer;

wherein the output potential of the voltage changer is electrically connected to the other of the anode and the cathode of said EL element via a switch, and

wherein the switch is provided external to the pixels.

35. An active matrix display device according to claim 34, wherein said plurality of pixels, said sensor, said CPU, and said voltage changer are formed over a same substrate.

36. An active matrix display device according to claim 34, further comprising an A/D (analog-to-digital) converter interposed between said sensor and said CPU, and a D/A (digital-to-analog) converter interposed between said CPU and said voltage changer.

37. An active matrix display device according to claim 34, wherein said sensor comprises a CCD (charge-coupled device) or a photo-diode.

38. An active matrix display device according to claim 34, wherein said information signal comprises a user'"'"'s living-body information.

39. An active matrix display device according to claim 34, wherein said display device is incorporated in at least one selected from the group consisting of a video camera, a digital camera, a head-mount display, a car navigation system, a portable telephone, an image reproduction apparatus, a car audio equipment, and a personal computer.

41. An active matrix display device according to claim 34, wherein the transistor is a current controlling thin film transistor.

42. An active matrix display device according to claim 34, further comprising:

a switching thin film transistor electrically connected to a gate electrode of the transistor.

43. An active matrix display device according to claim 34, wherein the active layer of the thin film transistor comprises a monocrystalline semiconductor film.