Image display and image displaying method

• US 20020135553A1
• Filed: 04/25/2002
• Published: 09/26/2002
• Est. Priority Date: 03/14/2000
• Status: Abandoned Application

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Kamizawa, Sadaomi, Iwata, Akihiko, Urakabe, Takahiro, Nishino, Ko, Nagai, Haruhiko
• Application Number:
  US09/959,986
• Publication Number:
  US 20020135553A1
• Time in Patent Office: Days
• US Class Current: 345/89
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• 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 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2025 the sub-frames having all the same time duration
• CPC Class Codes: G09G 3/2077 by a combination of two or more gradation control methods
• CPC Class Codes: G09G 3/34 by control of light from an independent source
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

It is aimed to perform a gradation display by using a light source array. A pixel having a desired luminance Y can be displayed by changing an emission intensity P of LED light source during one pixel display period C and turning on and off LCD corresponding to the change of the emission intensity P of LED light source.

Claims

1. An image display apparatus which displays an image based on an image signal comprising:

a light source;

a light source driving circuit for inputting the image signal and controlling an emission of the light source;

an optical device in which optical switches, for inputting a beam output from the light source and modulating the beam, are arranged; and

an optical device driving circuit for inputting the image signal and controlling an operation time of each of the optical switches in the optical device,

wherein the emission of the light source and the operation time of each of the optical switches in the optical device are combined to perform a gradation display at each pixel.

2. The image display apparatus of claim 1, wherein the optical device driving circuit changes the operation time of each of the optical switches during one pixel display period based on an input image signal, and

the light source driving circuit sets an emission time period of the light source to be the one pixel display period and sets an emission intensity of the light source to be fixed during the one pixel display period.

3. The image display apparatus of claim 1, wherein the optical device driving circuit sets the operation time of each of the optical switches to be one pixel display period, and

the light source driving circuit sets an emission intensity of the light source to be fixed during the one pixel display period and changes an emission time period of the light source during the one pixel display period based on an input image signal.

4. The image display apparatus of claim 1, wherein the optical device driving circuit changes the operation time of each of the optical switches during one pixel display period based on an input image signal, and

the light source driving circuit sets an emission time period of the light source to be the one pixel display period and changes an emission intensity of the light source during the one pixel display period based on the input image signal.

5. The image display apparatus of claim 1, wherein the optical device driving circuit sets the operation time of each of the optical switches to be one pixel display period, and

the light source driving circuit changes an emission time period of the light source during the one pixel display period based on an input image signal and changes an emission intensity of the light source during the one pixel display period based on the input image signal.

6. The image display apparatus of claim 1, wherein the optical device driving circuit changes the operation time of each of the optical switches during one pixel display period based on an input image signal, and

the light source driving circuit sets an emission intensity of the light source to be fixed during the one pixel display period and changes an emission time period of the light source during the one pixel display period based on the input image signal.

7. The image display apparatus of claim 1, wherein the optical device driving circuit changes the operation time of each of the optical switches during one pixel display period based on an input image signal, and

the light source driving circuit changes an emission time period of the light source during the one pixel display period based on the input image signal, and changes an emission intensity of the light source during the one pixel display period based on the input image signal.

8. The image display apparatus of claim 1, wherein the light source is a light source array in which a plurality of light source units are arranged.

9. The image display apparatus of claim 8, wherein the light source array assigns one or more than one light source unit to one pixel of an LCD.

10. The image display apparatus of claim 4, wherein the light source driving circuit changes the emission intensity of the light source to be one of values of 2^N (N=0, 1, 2, 3, . . . ) during the one pixel display period, and

the optical device driving circuit selects the emission intensity being one of the values of 2^N (N=0, 1, 2, 3, . . . ) by turning on and off each of the optical switches during the one pixel display period.

23. The image display apparatus of claim 1, wherein the displaying the image is performed in color applying a color field sequential system in which displays of red, green, and blue are switched according as time passes.

26. The image display apparatus of claim 1, wherein the optical device is a liquid crystal display device, and the optical device driving circuit displays a gradation based on a digital gradation control system in which the liquid crystal display device is turned on and off by using one of a low temperature p-Si TFT AMD (polysilicon thin film transistor active matrix drive) and a PMD (passive matrix drive).

38. The image display apparatus of claim 1, wherein the light source includes one or more than one light source corresponding to a plurality of pixels.

11. An image display apparatus which displays an image based on an image signal comprising:

a light source array in which a plurality of light source units are arranged;

a light source driving circuit for inputting the image signal and controlling at least one of an emission intensity and an emission time period of each of the plurality of light source units in the light source array, based on an input image signal; and

an optical device in which optical switches for inputting beams output from the light source array and modulating the beams are arranged,

wherein at least one of the emission intensity and the emission time period of each of the plurality of light source units in the light source array is controlled to perform a gradation display at each pixel.

12. The image display apparatus of claim 11, wherein the image signal includes a plurality of pixel signals, and

the light source driving circuit extracts a pixel signal corresponding to each of the plurality of light source units in the light source array out of the plurality of pixel signals and controls the emission intensity of each of the plurality of light source units in the light source array.

13. The image display apparatus of claim 12, wherein the pixel signal includes a red signal, a green signal, and a blue signal,

the light source array includes a red light source, a green light source, and a blue light source for each of the plurality of light source units, and

the light source driving circuit controls the emission intensity of the red light source by using the red signal, the emission intensity of the green light source by using the green signal, and the emission intensity of the blue light source by using the blue signal.

14. The image display apparatus of claim 11, wherein each of the plurality of light source units corresponds to a pixel, and

the light source driving circuit controls the emission intensity of each of the plurality of light source units corresponding to each pixel.

15. The image display apparatus of claim 14, wherein the light source driving circuit changes the emission intensity of each of the plurality of light source units during one pixel display period.

16. The image display apparatus of claim 11 further comprising,

an optical device in which optical switches for inputting beams output from the light source array and modulating the beams are arranged, and

an optical device driving circuit for inputting the image signal and controlling an operation time of each of the optical switches during one pixel display period based on the input image signal.

18. The image display apparatus of claim 17, wherein the optical device driving circuit inputs the image signal composed of N subfields (SF_1, SF_2, . . . , SF_N) to which N (positive integer) number of unequal values (V_0, V_1, V_2, . . . , V_N−

1) are respectively assigned, divides the one pixel display period into (V₀+V₁+V₂+ . . . +V<sub>N−

1</sub>) periods, and turns on each of the optical switches during a period corresponding to values assigned to the subfields which has been turned on as the image signal.

19. The image display apparatus of claim 18, wherein the values V_0, V_1, V_2, . . . V_N−

1 are equal to 2⁰, 2^1, . . . , 2<sup>N−

1</sup>.

20. The image display apparatus of claim 19, wherein the optical device is one of an LCD (liquid crystal display) and a DMD (digital micromirror device).

21. The image display apparatus of claim 19, wherein the light source includes at least one of a lamp, a laser diode, a light emitting diode, an electro luminescence, and a field emission display.

22. The image display apparatus of claim 11, wherein the light source array includes at least one of a lamp, a laser diode, a light emitting diode, an electro luminescence, and a field emission display.

24. The image display apparatus of claim 23, wherein the color field sequential system is a system in which one frame display period is divided into three color field periods of a red field, a green field, and a blue field, and one pixel display period is included in each of the three color field periods.

25. The image display apparatus of claim 23, wherein the color field sequential system is a system in which one frame display period is divided into a plurality of subfields, each of the plurality of subfields is further divided into three color field periods of a red field, a green field, and a blue field, and one pixel display period is included in one frame display period.

28. The image display apparatus of claim 27, wherein the light source includes a red light source, a green light source, and a blue light source, and

the light source driving circuit sets the color temperature of white by adjusting an emission time ratio among the red light source, the green light source, and the blue light source.

29. The image display apparatus of claim 28, wherein the light source driving circuit controls a gradation by changing at least one of an emission intensity and an emission time period of the light source, with keeping the emission time ratio among the red light source, the green light source, and the blue light source.

30. The image display apparatus of claim 27, wherein the light source includes a red light source, a green light source, and a blue light source, and

the light source driving circuit sets a color temperature of white by adjusting an emission intensity ratio among the red light source, the green light source, and the blue light source.

31. The image display apparatus of claim 30, wherein the light source driving circuit controls a gradation by changing at least one of an emission intensity and an emission time period of the light source, with keeping the emission intensity ratio among the red light source, the green light source, and the blue light source.

17. An image display apparatus which displays an image based on an image signal comprising:

a light source;

an optical device in which optical switches for inputting a beam output from the light source and modulating the beam are arranged; and

an optical device driving circuit for inputting the image signal and controlling an operation time of each of the optical switches by way of unequally dividing one pixel display period based on an input image signal.

27. An image display apparatus which displays an image based on an image signal comprising:

a light source; and

a light source driving circuit for inputting the image signal and controlling an emission of the light source,

wherein the light source driving circuit sets a color temperature of white by controlling the emission of the light source.

32. An image display apparatus which displays an image based on an image signal comprising:

a light source array in which a plurality of light source units are arranged in a state that one or more than one of the plurality of light source units is located to be corresponding to one pixel; and

a light source driving circuit for inputting the image signal and controlling at least one of an emission intensity and an emission time period of each of the plurality of light source units in the light source array, based on a value of an input image signal,

wherein the image display apparatus performs a gradation display per pixel without using an optical device in which optical switches, for inputting beams and modulating the beams, are arranged.

39. The image display apparatus of claim 32, wherein the light source array includes at least one of a lamp, a laser diode, a light emitting diode, an electro luminescence and a field emission display.

33. An image display method of an image display apparatus, for displaying an image based on an image signal, which includes a light source and an optical device where optical switches for inputting a beam output from the light source and modulating the beam are arranged, the image display method comprising:

inputting the image signal and controlling an emission of the light source; and

inputting the image signal and controlling an operation time of each of the optical switches,

wherein the emission of the light source and the operation time of each of the optical switches in the optical device are combined to perform a gradation display at each pixel.

34. An image display method of an image display apparatus, for displaying an image based on an image signal, which includes a light source array where a plurality of light source units are arranged and an optical device where optical switches for inputting beams output from the light source array and modulating the beams are arranged, the image display method comprising:

inputting the image signal;

controlling an emission intensity of each of the plurality of light source units in the light source array based on an input image signal; and

performing a gradation display at each pixel by controlling the emission intensity of each of the plurality of light source units in the light source array.

35. An image display method of an image display apparatus, for displaying an image based on an image signal, which includes a light source and an optical device where optical switches, for inputting a beam output from the light source and modulating the beam, are arranged, the image display method comprising:

inputting the image signal, and controlling an operation time of each of the optical switches by unequally dividing one pixel display period based on an input image signal.

36. An image display method of an image display apparatus, for displaying an image based on an image signal, which includes a light source and a light source driving circuit for inputting the image signal and controlling an emission of the light source, the image display method comprising:

setting a color temperature of white based on controlling the emission of the light source by using the light source driving circuit.

37. An image display method of an image display apparatus, for displaying an image based on an image signal, which includes a light source array where a plurality of light source units are arranged, the image display method comprising:

inputting the image signal;

controlling at least one of an emission intensity and an emission time of each of the plurality of light source units in the light source array based on a value of an input image signal; and

performing a gradation display at each pixel without using an optical device in which optical switches for inputting beams and modulating the beams are arranged.