LIQUID CRYSTAL DISPLAY PANEL AND LIQUID CRYSTAL DISPLAY DEVICE

• US 20130155040A1
• Filed: 12/14/2012
• Published: 06/20/2013
• Est. Priority Date: 12/14/2011
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation), Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Inventors: KOBAYASHI, Takahiro, Umeda, Yoshio, Tanaka, Katuji
• Granted Patent: US 9,024,923 B2
• Time in Patent Office: Days
• US Class Current: 345/204
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G02B 6/0083 Details of electrical connections of light sources to drivers, circuit boards, or the like
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• 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
• CPC Class Codes: G09G 5/00 Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators image data processing or generation, in general G06T
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

The liquid crystal display panel includes a liquid crystal display unit, and a backlight unit illuminating the liquid crystal display unit. The backlight unit includes first and second white light-emitting diodes that respectively emit white light, and first and second drive units that respectively supply a current to the first and second white light-emitting diodes. The first and second drive units are respectively configured to be able to adjust supply current to the first and second white light-emitting diodes. Chromaticities of the first and second white light-emitting diodes are of a relationship of being positioned opposite each other across a blackbody locus on an xy chromaticity diagram. The first and second white light-emitting diodes change over time so that, on the xy chromaticity diagram, an intersection point of the blackbody locus and a line that passes through the chromaticities of the first and second white light-emitting diodes becomes constant.

Claims

1. A liquid crystal display panel, comprising:

a liquid crystal display unit that includes a display screen that displays an image; and

a backlight unit that illuminates the liquid crystal display unit from a rear face of the liquid crystal display unit, wherein

the backlight unit includes;

a first white light-emitting diode and a second white light-emitting diode that respectively emit white light;

a first drive unit that supplies a current to the first white light-emitting diode; and

a second drive unit that supplies a current to the second white light-emitting diode,

the first drive unit is configured to be able to adjust a supply current to the first white light-emitting diode,

the second drive unit is configured to be able to adjust a supply current to the second white light-emitting diode,

a chromaticity of the first white light-emitting diode and a chromaticity of the second white light-emitting diode are of a relationship of being positioned opposite each other across a blackbody locus on an xy chromaticity diagram, and

the first white light-emitting diode and the second white light-emitting diode change over time so that, on the xy chromaticity diagram, an intersection point of the blackbody locus and a line that passes through the chromaticity of the first white light-emitting diode and the chromaticity of the second white light-emitting diode becomes constant.

2. The liquid crystal display panel according to claim 1, wherein the first drive unit adjusts a supply current to the first white light-emitting diode and the second drive unit adjusts a supply current to the second white light-emitting diode so that a chromaticity of the light emitted from the backlight unit becomes constant.

3. The liquid crystal display panel according to claim 1, wherein the first white light-emitting diode and the second white light-emitting diode change over time so that, on the xy chromaticity diagram, the chromaticity of the first white light-emitting diode and the chromaticity of the second white light-emitting diode move on the line that passes through the chromaticity of the first white light-emitting diode and the chromaticity of the second white light-emitting diode.

4. The liquid crystal display panel according to claim 3, wherein

the first white light-emitting diode and the second white light-emitting diode respectively include:

a light-emitting diode chip that emits light of a predetermined wavelength; and

a phosphor that absorbs a part of the light emitted from the light-emitting diode chip to emit light of a wavelength different from the predetermined wavelength,

a material foaming the respective light-emitting diode chips of the first white light-emitting diode and the second white light-emitting diode and a composition of the material forming the light-emitting diode chips are mutually the same, and

a material forming the respective phosphors of the first white light-emitting diode and the second white light-emitting diode and a composition of the material forming the phosphors are mutually the same.

5. The liquid crystal display panel according to claim 1, further comprising a light guide plate that is disposed on a rear face side of the display screen of the liquid crystal display unit and guides incident light to the display screen, wherein

the first white light-emitting diode and the second white light-emitting diode are alternately disposed along at least one end part of the light guide plate, and emit the white light toward the end part.

6. The liquid crystal display panel according to claim 1, further comprising a light guide plate that is disposed on a rear face side of the display screen of the liquid crystal display unit and guides incident light to the display screen, wherein

the first white light-emitting diode and the second white light-emitting diode are alternately disposed at a side of the light guide plate opposite to the display screen facing the light guide plate, and emit the white light toward the light guide plate.

7. A liquid crystal display device, comprising:

the liquid crystal display panel according to claim 1; and

a control circuit that controls the liquid crystal display unit of the liquid crystal display panel based on an input image signal.