LCD device having a homogeneous LC layer

• US 20060209004A1
• Filed: 12/08/2005
• Published: 09/21/2006
• Est. Priority Date: 12/08/2004
• Status: Abandoned Application

• Current Assignee: NEC LCD Technologies Limited (Tianma Microelectronics Company Limited)
• Original Assignee: NEC LCD Technologies Limited (Tianma Microelectronics Company Limited)
• Inventors: Ikeno, Hidenori, Nagai, Hiroshi
• Application Number:
  US11/297,272
• Publication Number:
  US 20060209004A1
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2300/0434 Flat panel display in which a field is applied parallel to the display plane
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

An LCD device includes an LC panel, and a backlight unit having a backlight source and a luminous intensity control unit. The backlight source has a peak luminous intensity in each of wavelength ranges corresponding to red, green and blue colors. The luminous intensity control unit controls the peak luminous intensity of the wavelength range corresponding to the blue color at a lower gray scale level of the LCD unit to be lower than that at a higher gray scale level, to thereby prevent the chromaticity on the screen from shifting toward blue color.

Claims

1. A liquid crystal display (LCD) device comprising a pair of transparent substrates, a homogeneously aligned liquid crystal (LC) layer sandwiched therebetween and including therein LC molecules having longer axes aligned in parallel to a surface of said transparent substrates, and a backlight unit,supplying backlight to said LC layer, wherein;

said backlight unit comprises a backlight source having a peak luminous intensity in each of first through third wavelength ranges of 380 to 490 nm, 490 to 590 nm and 590 to 800 nm, respectively, and a luminous intensity control unit for controlling a luminous intensity of said backlight source to control a gray scale level of said LCD device; and

said luminous intensity control unit controls said peak luminous intensity of said first wavelength range at a first gray scale level to be lower than said peak luminous intensity of said first wavelength range at a second gray scale level which is higher than said first gray scale level.

2. The LCD device according to claim 1, wherein said second gray scale level is the highest gray scale level of said LCD device.

3. The LCD device according to claim 1, wherein said first gray scale level is the lowest gray scale level of said LCD device.

4. The LCD device according to claim 1, wherein, assuming that Lwb is the peak luminous intensity of said first wavelength range upon display of white color in said LCD device, and that said gray scale level is divided into 100 levels, with black color being a zero level and white color being a 99 level in terms of intensity,

said luminous intensity control unit controls said backlight source so that said luminous intensity of said first wavelength range assumes 0.5×

Lwb to 0.85×

Lwb at a gray scale level between a zero level and a 15 level, and 0.7×

Lwb to 1.0×

Lwb at a gray scale level between a 16 level and a 25 level.

5. The LCD device according to claim 1, wherein, assuming that said peak luminous intensities of said first through third wavelength ranges are Lwb, Lwg and Lwr, respectively, upon display of white color in said LCD device, and that said gray scale level of said LCD device is divided into 100 levels, with black color being a zero level and white color being a 99 level in terms of intensity,

said luminous intensity control unit controls said backlight source so that a ratio among said peak luminous intensities of said first through third wavelength ranges assumes 0.5×

Lwb to 0.85×

Lwb;

Lwg;

Lwr at a gray scale level between a zero level and a 15 level, and assumes 0.7×

Lwb to 1.0×

Lwb;

Lwg;

Lwr at a gray scale level between a 16 level and a 25 level.

6. The LCD device according to claim 1, wherein said luminous intensity control unit controls an overall luminous intensity of said first wavelength range at said first gray scale level to be lower than an overall luminous intensity of said first wavelength range at said second gray scale level.

7. A liquid crystal display (LCD) device comprising a pair of transparent substrates, a homogeneously aligned liquid crystal (LC) layer sandwiched therebetween and including therein LC molecules having longer axes aligned in parallel to a surface of said transparent substrates, and a backlight unit supplying backlight to said LC layer, wherein:

said backlight unit comprises a backlight source having a peak luminous intensity in each of first through third wavelength ranges of 380 to 490 nm, 490 to 590 nm and 590 to 800 nm, respectively, and a luminous intensity control unit for controlling a luminous intensity of said backlight source to control a gray scale level of said LCD device in each of a plurality of divided screen areas of said LCD device; and

said luminous intensity control unit controls said peak luminous intensity of said first wavelength range, in a first screen area representing a first gray scale level, to be lower than said peak luminous intensity of said first wavelength range in a second screen area representing a second gray scale level which is higher than said first gray scale level.

8. The LCD device according to claim 7, wherein said second gray scale level is the highest gray scale level of said LCD device.

9. The LCD device according to claim 7, wherein said first gray scale level is the lowest gray scale level of said LCD device.

10. The LCD device according to claim 7, wherein, assuming that Lwb is the peak luminous intensity of said first wavelength range upon display of white color in said LCD device, and that said gray scale level of said LCD device is divided into 100 levels, with black color being a zero level and white color being a 99 level in terms of intensity,

said luminous intensity control unit controls said backlight source so that said luminous intensity of said first wavelength range in each of said divided screen area assumes 0.5×

Lwb to 0.85×

Lwb at a gray scale level between a zero level and a 15 level, and assumes 0.7×

Lwb to 1.0×

Lwb at a gray scale level between a 16 level and a 25 level.

11. The LCD device according to claim 7, wherein, assuming that said peak luminous intensities of said first through third wavelength ranges are Lwb, Lwg and Lwr, respectively, upon display of white color in said LCD device, and that said gray scale level of said LCD device is divided into 100 levels, with black color being a zero level and white color being a 99 level,

said luminous intensity control unit controls said backlight source so that a ratio among peak luminous intensities of said first through third wavelength ranges in each of said divided screen areas assumes 0.5×

Lwb to 0.85×

Lwb;

Lwg;

Lwr at a gray scale level between a zerolevel and a 15 level, and assumes 0.7×

Lwb to 1.0×

Lwb;

Lwg;

Lwr at a gray scale level between a 16 level and a 25 level.

12. The LCD device according to claim 7, wherein said luminous intensity control unit controls, in each of divided screen areas, an overall luminous intensity of said first wavelength range at said first gray scale level to be lower than an overall luminous intensity of said first wavelength range at said second gray scale level.