# US 2013/0155040 A1 · Liquid crystal display panel and liquid crystal display device

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- Number: US 2013/0155040 A1
- Document ID: US20130155040A1
- Status: Published application
- Kind: A1
- Application number: 13/715,960
- Filed: 2012-12-14
- Published: 2013-06-20
- Earliest claimed: 2011-12-14
- Assignees: Panasonic Corporation; Panasonic Liquid Crystal Display Co., Ltd.
- Inventors: Takahiro KOBAYASHI; Yoshio Umeda; Katuji Tanaka
- Web page: https://patentgrep.com/patent/US20130155040A1

## CPC

- G02F 1/133603: {with LEDs}
- G02B 6/0073: {Light emitting diode [LED]}
- G02B 6/0083: {Details of electrical connections of light sources to drivers, circuit boards, or the like}
- G09G 3/3406: {Control of illumination source (illumination devices structurally associated with liquid crystal cells G02F1/1336)}
- G09G 3/3413: {Details of control of colour illumination sources}
- 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)
- G09G 3/342: {using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines}
- G09G 2320/0233: Improving the luminance or brightness uniformity across the screen
- G09G 2320/0242: Compensation of deficiencies in the appearance of colours
- G09G 2320/045: Compensation of drifts in the characteristics of light emitting or modulating elements
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)

## 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

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 1)

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.

### Claim 4 (depends on 3)

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.

### Claim 5 (depends on 1)

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.

### Claim 6 (depends on 1)

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.

### Claim 7 (depends on 1)

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.