Surface light source device and liquid crystal display unit

Patent metadata

Field	Value
Publication number	US-10650756-B2
Application number	US-57985609-A
Country	US
Kind code	B2
Filing date	Oct 15, 2009
Priority date	Jun 21, 2006
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

A surface light source device which illuminates a transmission-type liquid crystal display unit from the back surface includes P×Q surface light source units with individually controlled light sources. Each of the light sources includes a plurality of light-emitting element units. Each of the light-emitting element units includes at least one red light-emitting element that emits red light, at least one green light-emitting element that emits green light, and at least one blue light-emitting element that emits blue light. The center of mass of a luminance profile based on each of a plurality of red light-emitting elements, a plurality of green light-emitting elements, and a plurality of blue light-emitting elements in each surface light source unit substantially coincides with the center of mass of the surface light source unit.

First claim

What is claimed is:

1. A surface light source device which illuminates a transmission-type liquid crystal display unit from a back surface, the liquid crystal display unit having a display area including pixels arranged in a two-dimensional matrix, the surface light source device comprising:
P×Q surface light source units corresponding to P×Q imaginary display area units obtained by assuming that the display area of the liquid crystal display unit is divided into the P×Q imaginary display area units,
wherein:
light sources included in the surface light source units are individually controlled and are configured to emit white light,
the P×Q surface light source units comprise at least one first surface light source unit and each of the at least one first surface light source units includes first light sources,
the white light emitted by the first light sources of each of the at least one first surface light source units has a luminance profile, and
for each luminance profile of the white light emitted by the first light sources of each of the at least one first surface light source unit, a center of mass of that luminance profile is located inside a circle of diameter D drawn around a center of mass of a corresponding first surface light source unit of the at least one first surface light source unit, such that the first light sources of that corresponding first surface light source unit are configured to emit white light for an entirety of the surface light source unit, where D is determined by the equation D=0.2 S 0 1/2 and S 0 is a surface area of that corresponding first surface light source unit.

2. The surface light source device of claim 1 , wherein each light source of the light sources of the surface light source units are individually controlled such that an emitted luminescence of light emitted by the light source is at a maximum value by adjusting a generated luminescence of light generated by a light-emitting circuit and/or by adjusting a transmittance of the light source such that the generated luminescence and the transmittance are at a predetermined ratio.

3. The surface light source device of claim 2 , wherein the maximum value is determined based on a light that would be generated when a maximum control signal able to be applied to the light source is applied to the light source.

4. The surface light source device of claim 2 , wherein the predetermined ratio is based on a maximum possible luminescence of the light source and a maximum possible transmittance of the light source.

5. The surface light source device of claim 1 , further comprising:
a controlling unit configured to control a luminance of the light sources of the surface light source units; and
a driving circuit configured to control a transmittance of said liquid crystal display unit, wherein the driving circuit is configured to set a transmittance of at least one of said pixels of the display area to a specified value based at least in part on a control performed by the controlling unit of a luminance of a first light source at a position in the surface light source device corresponding to the at least one pixel,
wherein the driving circuit is configured to set the transmittance of the at least one pixel to achieve a pixel luminance for the at least one pixel equivalent to a pixel luminance that could be achieved for the at least one pixel when the controlling unit applies a maximum signal to the first light source.

6. The surface light source device of claim 5 , wherein said maximum signal is a maximum value among signals that the controlling unit can apply to red light sources, green light sources, and blue light sources.

7. A surface light source device which illuminates a transmission-type liquid crystal display unit from a back surface, the liquid crystal display unit having a display area including pixels arranged in a two-dimensional matrix, the surface light source device comprising:
P×Q surface light source units partitioned from one another by partition walls,
wherein
each of the surfaces of the partition walls diffuse reflected light or specularly reflect light;
light sources included in the surface light source units are individually controlled, and
a light source included in each of the surface light source units includes a light-emitting circuit, the light-emitting circuit comprising at least one light-emitting unit, each of the at least one light-emitting unit being positioned in an area of the light source such that the light-emitting circuit is arranged to emit white light of a uniform color for an entirety of the surface light source unit, the at least one light-emitting unit being positioned such that a center of mass of the luminance profile for the at least one light-emitting unit coincides with a center of mass of an area defined by the partition walls of the surface light source unit such that the at least one light-emitting unit is configured to emit white light of a uniform color for an entirety of the surface light source unit.

8. A transmission-type liquid crystal display unit which has a display area including pixels arranged in a two-dimensional matrix, comprising a surface light source device that illuminates the liquid crystal display unit from a back surface,
wherein:
the surface light source device includes P×Q surface light source units corresponding to P×Q imaginary display area units obtained by assuming that the display area of the liquid crystal display unit is divided into the P×Q imaginary display area units;
light sources included in the surface light source units are individually controlled and are configured to emit white light;
the P×Q surface light source units comprise at least one first surface light source unit and each of the at least one first surface light source units includes first light sources,
the white light emitted by the first light sources of each of the at least one first surface light source units has a luminance profile, and
for each luminance profile of the white light emitted by the first light sources of each of the at least one first surface light source unit, a center of mass of that luminance profile is located inside a circle of diameter D drawn around a center of mass of a corresponding first surface light source unit of the at least one first surface light source unit, such that the first light sources of that corresponding first surface light source unit are configured to emit white light for an entirety of the surface light source unit, where D is determined by the equation D=0.2 S 0 1/2 and S 0 is a surface area of that corresponding first surface light source unit.

Assignees

• Aoki Tomio
• Hayashi Masatake
• Masuda Shozo
• Morimoto Tadashi
• Saturn Licensing Llc

Inventors

• Aoki Tomio
• Hayashi Masatake
• Masuda Shozo
• Morimoto Tadashi

Classifications

• G09G2320/064

  by time modulation of the brightness of the illumination source · CPC title

• G09G3/3426 Primary

  the different display panel areas being distributed in two dimensions, e.g. matrix · CPC title

• G09G2360/145

  the light originating from the display screen · CPC title

• G02F1/133603

  with LEDs · CPC title

• G09G3/3413

  Details of control of colour illumination sources · CPC title