Liquid crystal display device, image display device, illumination device and emitter used therefor, driving method of liquid crystal display device, driving method of illumination device, and driving method of emitter

• US 7,903,062 B2
• Filed: 04/28/2005
• Issued: 03/08/2011
• Est. Priority Date: 06/15/2000
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Jinda, Akihito, Shiomi, Makoto, Miyachi, Koichi
• Primary Examiner(s): Abdulselam; Abbas I
• Application Number:
  US11/116,281
• Publication Number:
  US 20050206589A1
• Time in Patent Office: 2,140 Days
• Field of Search: 345/87, 345/73, 345/204, 345/208, 345/77, 345/89, 345/102, 345/690, 345 93- 94, 348/752, 362/561
• US Class Current: 345/87
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2310/066 Waveforms comprising a gently increasing or decreasing portion, e.g. ramp
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2330/06 Handling electromagnetic interferences [EMI], covering emitted as well as received electromagnetic radiation
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines

Abstract

The cold cathode tube for illuminating pixels with light which is in accordance with an output signal has luminance which gradually increases at a rise and gradually decreases at a fall per one frame time. The cold cathode tube contains a fluorescent material of only one of three primary colors of light, and has a certain OFF period or dimming period per one frame time. Between a diffusing plate and a reflecting plate are provided partition walls for parting emitting areas, so that the illumination light of one cold cathode tube does not reach the display elements to be illuminated by the other cold cathode tubes. The emission of each display element is changed per one frame time between a normal ON state and a dim state. The cold cathode tube has two or more OFF periods within one frame time, and, luminance of the cold cathode tube is changed per one frame period. As a result, it is possible to suppress shortening of life of emitters in an illuminating section, and to relieve lowering of luminance of the emitters, and also to obtain a desirable display quality even in a fast-moving image.

Claims

1. A liquid crystal display device, comprising:

an emitter for illuminating pixels with light which is in accordance with a driving signal; and

emission control means for controlling the driving signal so that an emission waveform of the emitter has an ON period which has a first luminance and an OFF period which has a second luminance darker than the first luminance, wherein a rise and a fall of the emission waveform of the emitter at a timing of a change between the ON period and the OFF period are slacked per one vertical period, wherein said emission control means slacks a rise and a fall of a waveform of the driving signal and/or of an envelope of the waveform of the driving signal.

2. The liquid crystal display device as set forth in claim 1, further comprising an inverter control circuit for providing an inverter input signal to an inverter which in turn provides an inverter output signal to the emitter, and wherein a rise and fall of a waveform of each of the inverter input signal and the inverter output signal are slacked.

3. The liquid crystal display device as set forth in claim 1, wherein said emission control means is adapted so that a rise and a fall of a waveform of the driving signal essentially become part of a sinusoidal wave.

4. The liquid crystal display device as set forth in claim 1, wherein said emission control means is adapted so that a rise and a fall of an envelope of a waveform of the driving signal essentially become part of a sinusoidal wave.

5. The device of claim 1, wherein a switching timing between the ON period and the OFF period of the emitter can be determined regardless of a timing of selecting each scanning line.

6. The device of claim 1, wherein by means of that the rise and fall of a waveform of the driving signal or its envelope are slacked, the rise and fall of the emission waveform of the emitter are more remarkably slacked than a case that the rise and fall of a waveform of the driving signal or its envelope are not slacked.

7. A liquid crystal display device, comprising:

an emitter for illuminating pixels with light which is in accordance with a driving signal; and

emission control means for controlling the driving signal so that the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage, wherein the driving signal makes up a sinusoidal wave whose frequency essentially matches an inverse of a vertical period.

8. A liquid crystal display device, comprising:

an emitter for illuminating pixels with light which is in accordance with a driving signal; and

emission control means for controlling the driving signal so that an envelope of the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage, wherein the envelope of the driving signal makes up a sinusoidal wave where the envelope has a frequency which essentially matches an inverse of a vertical period.

9. A liquid crystal display device, comprising:

an emitter for illuminating pixels with light which is in accordance with a driving signal; and

emission control means for controlling the driving signal so that the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage, wherein the driving signal makes up a Gaussian distribution waveform whose repetitive period essentially matches a vertical period.

10. A liquid crystal display device, comprising:

an emitter for illuminating pixels with light which is in accordance with a driving signal; and

emission control means for controlling the driving signal so that an envelope of the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage, wherein the envelope of the driving signal makes up a Gaussian distribution waveform where the envelope has a repetitive period which essentially matches a vertical period.

11. A liquid crystal display device, comprising:

an emitter for illuminating pixels with light which is in accordance with a driving signal; and

emission control means for controlling the driving signal so that the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage, wherein the driving signal makes up a Lorentz distribution waveform whose repetitive period essentially matches a vertical period.

12. A liquid crystal display device, comprising:

an emitter for illuminating pixels with light which is in accordance with a driving signal; and

emission control means for controlling the driving signal so that an envelope of the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage, wherein the envelope of the driving signal makes up a Lorentz distribution waveform where the envelope has a repetitive period which essentially matches a vertical period.

13. A liquid crystal display device, comprising:

an emitter for illuminating pixels with light which is in accordance with a driving signal; and

emission control means for controlling the driving signal so that the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage, wherein the driving signal makes up a triangular wave whose frequency essentially matches an inverse of a vertical period.

14. A liquid crystal display device, comprising:

an emitter for illuminating pixels with light which is in accordance with a driving signal; and

emission control means for controlling the driving signal so that an envelope of the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage, wherein the envelope of the driving signal makes up a triangular wave where the envelope has a frequency which essentially matches an inverse of a vertical period.

15. A driving method of a liquid crystal display device comprising:

controlling a driving signal of an emitter provided in a liquid crystal display device so that the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage, and

slacking a rise and a fall of the driving signal at a timing of a change between the ON period and the OFF period per one vertical period.

16. The driving method as set forth in claim 15, wherein a driving signal line associated with the driving signal is grounded via a capacitor.

17. The method of claim 15, further comprising providing an inverter input signal to an inverter which in turn provides an inverter output signal to the emitter, and wherein a rise and fall of a waveform of each of the inverter input signal and the inverter output signal are slacked.

18. The method of claim 15, wherein a switching timing between the ON period and the OFF period of the emitter can be determined regardless of a timing of selecting each scanning line.

19. The method of claim 15, wherein by means of that the rise and fall of a waveform of the driving signal or its envelope are slacked, the rise and fall of the emission waveform of the emitter are more remarkably slacked than a case that the rise and fall of a waveform of the driving signal or its envelope are not slacked.

20. A driving method of a liquid crystal display device comprising:

controlling a driving signal of an emitter provided in a liquid crystal display device so that the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage, and

slacking a rise and a fall of an envelope of the driving signal at a timing of a change between the ON period and the OFF period per one vertical period.

21. The driving method as set forth in claim 20, wherein a driving signal line associated with the driving signal is grounded via a capacitor.

22. A driving method of a liquid crystal display device comprising:

setting a driving signal of an emitter provided in a liquid crystal display device so that the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and wherein the driving signal has a periodic waveform which is in synchronism with a vertical synchronize signal,

wherein a rise and a fall of the periodic waveform make up part of a sinusoidal wave.

23. A driving method of a liquid crystal display device comprising:

setting an envelope of a driving signal of an emitter provided in a liquid crystal display device so that the envelope of the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and wherein the envelope of the driving signal has a periodic waveform which is in synchronism with a vertical synchronize signal, and

wherein a rise and a fall of the periodic waveform make up part of a sinusoidal wave.

24. A driving method of a liquid crystal display device comprising:

setting a driving signal of an emitter provided in a liquid crystal display device so that the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and wherein the driving signal has a periodic waveform which is in synchronism with a vertical synchronize signal, and

wherein the periodic waveform is essentially a sinusoidal wave.

25. A driving method of a liquid crystal display device comprising:

setting an envelope of a driving signal of an emitter provided in a liquid crystal display device so that the envelope of the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and wherein the envelope of the driving signal has a periodic waveform which is in synchronism with a vertical synchronize signal, and

wherein the periodic waveform is essentially a sinusoidal wave.

26. A driving method of a liquid crystal display device comprising:

setting a driving signal of an emitter provided in a liquid crystal display device so that the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and wherein the driving signal has a periodic waveform which is in synchronism with a vertical synchronize signal, and

wherein the periodic waveform is essentially a repetition of a Gaussian distribution waveform.

27. A driving method of a liquid crystal display device comprising:

setting an envelope of a driving signal of an emitter provided in a liquid crystal display device so that the envelope of the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and wherein the envelope of the driving signal has a periodic waveform which is in synchronism with a vertical synchronize signal, and

wherein the periodic waveform is essentially a repetition of a Gaussian distribution waveform.

28. A driving method of a liquid crystal display device comprising:

setting a driving signal of an emitter provided in a liquid crystal display device so that the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and wherein the driving signal has a periodic waveform which is in synchronism with a vertical synchronize signal, and

wherein the periodic waveform is essentially a repetition of a Lorentz distribution waveform.

29. A driving method of a liquid crystal display device comprising:

setting an envelope of a driving signal of an emitter provided in a liquid crystal display device so that the envelope of the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and wherein the envelope of the driving signal has a periodic waveform which is in synchronism with a vertical synchronize signal, and

wherein the periodic waveform is essentially a repetition of a Lorentz distribution waveform.

30. A liquid crystal display device comprising:

an emitter for illuminating pixels with light which is in accordance with a driving signal, the emitter receiving such a driving signal where the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage, and

wherein a rise and fall of the driving signal at a timing of a change between the ON period and the OFF period are slacked per one vertical period.

31. A liquid crystal display device comprising:

an emitter for illuminating pixels with light which is in accordance with a driving signal, the emitter receiving such a driving signal that an envelope of the driving signal has an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage, wherein a rise and a fall of the envelope of the driving signal at a timing of a change between the ON period and the OFF period are slacked per one vertical period.

32. A liquid crystal display device comprising:

an emitter which receives a driving signal having an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and where the driving signal has a periodic waveform in synchronism with a vertical synchronize signal, and

wherein a rise and a fall of the periodic waveform make up part of a sinusoidal wave.

33. A liquid crystal display device comprising:

an emitter which receives a driving signal where an envelope of the driving signal comprises an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and where the envelope of the driving signal has a periodic waveform in synchronism with a vertical synchronize signal, and

wherein a rise and a fall of the periodic waveform make up part of a sinusoidal wave.

34. A liquid crystal display device comprising:

an emitter which receives a driving signal having an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and where the driving signal has a periodic waveform in synchronism with a vertical synchronize signal, and

wherein the periodic waveform is essentially a sinusoidal wave.

35. A liquid crystal display device comprising:

an emitter which receives a driving signal where an envelope of the driving signal comprises an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and where the envelope of the driving signal has a periodic waveform in synchronism with a vertical synchronize signal, and

wherein the periodic waveform is essentially a sinusoidal wave.

36. A liquid crystal display device comprising:

an emitter which receives a driving signal having an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and where the driving signal has a periodic waveform in synchronism with a vertical synchronize signal, and

wherein the periodic waveform is essentially a repetition of a Gaussian distribution waveform.

37. A liquid crystal display device comprising:

an emitter which receives a driving signal where an envelope of the driving signal comprises an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and where the envelope of the driving signal has a periodic waveform in synchronism with a vertical synchronize signal, and

wherein the periodic waveform is essentially a repetition of a Gaussian distribution waveform.

38. A liquid crystal display device comprising:

an emitter which receives a driving signal having an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and where the driving signal has a periodic waveform in synchronism with a vertical synchronize signal, and

wherein the periodic waveform is essentially a repetition of a Lorentz distribution waveform.

39. A liquid crystal display device comprising:

an emitter which receives a driving signal where an envelope of the driving signal comprises an ON period which has a first voltage and an OFF period which has a second voltage lower than the first voltage per one vertical period, and where the envelope of the driving signal has a periodic waveform in synchronism with a vertical synchronize signal, and

wherein the periodic waveform is essentially a repetition of a Lorentz distribution waveform.

40. A liquid crystal display device, comprising:

an emitter for illuminating pixels with light which is in accordance with a driving signal; and

emission control means for controlling the driving signal so that one vertical synchronize period includes two or more of separate periods of reduced luminance of the emitter, and that luminance of the emitter is changed by a period of one vertical synchronize period.

41. The liquid crystal display device as set forth in claim 40, wherein said emission control means is adapted to incorporate a small pulse in the driving signal of a certain period of reduced luminance, which is provided per one vertical synchronize signal, so as to divide the period of reduced luminance.

42. The liquid crystal display device as set forth in claim 40, wherein said emission control means is further adapted to slack a rise and a fall of a waveform of the driving signal.

43. The liquid crystal display device as set forth in claim 40, wherein said emitter is one of a cold cathode tube, a light-emitting diode element, an electroluminescence element, a hot cathode tube, a mercury lamp, a halogen lamp, and a laser.