News Column

Patent Application Titled "Light Source Apparatus and Liquid Crystal Display Apparatus" Published Online

May 8, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors Takasi, Motoki (Osaka-shi, JP); Takemura, Hideo (Osaka-shi, JP), filed on May 18, 2012, was made available online on April 24, 2014.

The assignee for this patent application is Sharp Kabushiki Kaisha.

Reporters obtained the following quote from the background information supplied by the inventors: "Conventional liquid crystal display devices of this type have a transmissive liquid crystal panel, and a backlight is used in the back of the transmissive liquid crystal panel. For the light source apparatus used as a backlight, CCFL (Cold Cathode Fluorescent Lamp) has conventionally been a main stream. However, with recent progress in LED technology, use of the LED as a light source is regarded as promising instead of using the CCFL.

"In a direct LED backlight of Patent Document 1, a method is used for controlling streaked and uneven brightness due to the overlapping of shadows created by pillars and adhesive resin of optical lenses blocking light from a light emitting element. However, optical diffusing lenses used therein are all the same.

"FIG. 11 is a longitudinal cross sectional view showing a configuration example of an essential part of a conventional light emitting module, on which a light emitting element disclosed in Patent document 1 is mounted. FIG. 12 is a plane view showing an arrangement example of optical lenses in a plane emitting unit on which a plurality of light emitting element modules of FIG. 11 are mounted.

"As shown in FIG. 11, in a light emitting element module 100, a plurality of light emitting element parts 102 are mounted on a substrate 101 as light emitting elements, the light emitting element parts 102 being equipped with LEDs and the light emitting element parts 102 being arranged either in one column or in a plurality of columns.

"In the substrate 101, wiring is provided on a base material 101a formed by impregnating, for example, a resin (epoxy resin, cyanate resin and the like) into woven or non-woven, glass fiber, organic fiber or the like. White insulation material (white resist and the like) 101b is formed on the uppermost surface of the substrate 101 in such a manner to cover a region except for a land part in the wiring. Covering the uppermost surface of the substrate 101 with the white insulation material 101b increases reflection rate of light from the light emission elements and increases light irradiation amount to a display area, in addition to protecting the wiring. Note that ordinary solder resist can be used if a reflection sheet is provided separately on the surface of the substrate.

"In a light emitting element part 102, one or a plurality of LED chips (not shown) are mounted on a part substrate 102a such as ceramic, and the LED chips are electrically connected to the part substrate 102a with wires (not shown). Thus, the LED chips and wires are formed by being sealed by a sealing resin 102b. For the seal resin 102b, transparent resin such as silicon is used, and fluorescent materials are added as needs arise.

"The substrate 101 has an opening 101d which is not covered with the insulating materials 101b. In the opening 101d, an optical lens 103 and the base material 101a of the substrate 101 are fixed with adhesive resin 104.

"The size of the opening 101d is the same as, or slightly greater than, that of a bottom surface of a pillar 103a of the optical lens 103. As such, providing the opening 101d the size of which is the same as or slightly greater than the size of the bottom surface of the pillar 103a facilitates the positioning of the adhesive resin 104, thus facilitating the control of resin amount. If the amount of the adhesive resin 104 is too much, then the adhesive resin 104 will rise up to the bottom surface of the lens section 103b of the optical lens 103, or will spread to the surface of substrate 101 beyond the opening 101d. As a result, transmitted light may be blocked or absorbed at the bottom surface of the lens section 103b or the pillar 103a, which may influence the diffusion of light from the light emitting element.

"At the center of the optical lens 103, a recess 103c is formed for partially housing the light emitting element part 102 from the bottom. The light emitting element part 102 is not sealed and has a layer of air between the light emitting element part 102 and the recess 103C, which provides favorable heat radiation of the light emitting element part 102.

"In addition, in a conventional plane light emission unit 110 as shown in FIG. 12, pillars 103a of each of optical lenses 103 and adhesive resins 104 adjacent to each other are arranged to commonly prevent a straight line L1 in a longitudinal direction and a straight line L2 in a transverse direction, where the lines connect the centers of the light emitting element parts 102 adjacent to each other. As a result, shadows created by pillars 103a of the optical lenses 103 and adhesive resins 104 blocking light from a light emitting element will not overlap with each other, thereby controlling the occurrence of streaked and uneven brightness."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "Problems to be Solved by the Invention

"In the above conventional plane light emitting unit 110 disclosed in Patent Document 1, when the light diffusing lenses 103 are arranged in a matrix and in a longitudinal and transverse array as shown in FIG. 12, the spread of individual light of many of the light emitting element parts 102 link with light of an adjacent light diffusing lens 103. Therefore, uneven emission of light is likely to occur, which is a certain pattern of longitudinal streaks, transverse streaks and oblique streaks as a whole backlight. In particular, uneven emission of streaks occurring throughout an entire screen are obvious to human eyes, which is one of the reasons that reduces a display quality.

"Unevenness of the same type occurring continuously at a proximal position is more visible to human eyes than unevenness of the same type occurring at a location farther than the proximal position, even if the two types of unevenness have the same brightness difference.

"In addition, when the distance between a light emitting element and a light diffusing sheet is narrowed down to performance limitation or when the pitch distance of light emitting elements mounted in a planar manner is widened to performance limitation, there arises a problem with a conventional configuration with a single light distribution property, of insufficient spreading of light from the center of the light emitting element to the peripheral portion depending on a deviation in properties due to variation on production of light emitting element modules. Thus, the brightness is relatively decreased at the middle point between the light emitting elements in a plane view, and the brightness immediately above the light emitting elements is relatively increased to generate lattice like unevenness, which affects the display quality.

"The present invention is intended to solve the conventional problems described above. It is an objective of the present invention to provide: a light source apparatus capable of controlling brightness unevenness of a plane light source to increase display quality of the plane light source; and a liquid crystal display apparatus with the light source apparatus used therein.

"Means for Solving the Problem

"A light source apparatus according to the present invention comprises a plurality of light emitting element modules provided therein, in which one or a plurality of light emitting elements are mounted on a substrate, for emitting light planarly, where a light source section causing first unevenness and a light source section causing second unevenness are alternately arranged, so that the first unevenness and the second unevenness are relieved with each other, thereby achieving the objective described above.

"Preferably, in the light source apparatus according to the present invention, alight source section causing lattice like unevenness by a light part and a light source section causing oblique like unevenness by a light part are alternately arranged for each row or each column when a plurality of light source sections are arranged in a matrix in a row direction and a column direction in a plane view.

"A light source apparatus according to the present invention comprises a plurality of light emitting element modules provided therein, in which one or a plurality of light emitting elements are mounted on a substrate, for emitting light planarly, the light source apparatus further comprising a light source section with a narrow light distribution property and a light source section with a broad light distribution property being alternately arranged for each row or each column when a plurality of the light source sections are arranged in a matrix in a row direction and a column direction in a plane view, thereby achieving the objective described above.

"Preferably, in a light source apparatus according to the present invention, a light source section with a large light and dark contrast difference and a light source section with a small light and dark contrast difference are alternately arranged in the light emitting element module for each row or each column when a plurality of the light source sections are arranged in a matrix in a row direction and a column direction in a plane view.

"Still preferably, in a light source apparatus according to the present invention, a light emitting element module comprising one or a plurality of light source sections with a large light and dark contrast difference, and a light emitting element module comprising one or a plurality of light source sections with a small light and dark contrast difference, are alternately arranged.

"Still preferably, in the light emitting element module in the light source apparatus according to the present invention, a light source section with a large light and dark contrast difference and a light source section with a small light and dark contrast difference are alternately arranged.

"Still preferably, in the light source apparatus according to the present invention, the light source section comprises a reflecting material provided on a substrate region around the light emitting element, in addition to the light emitting element; and the light source section with the large light and dark contrast difference and the light source section with the small light and dark contrast difference are formed by the difference in a reflection rate of the reflecting material.

"Still preferably, in the light source apparatus according to the present invention, a lens is mounted for each light emitting element, and the substrate region around the light emitting element is a substrate region immediately below the lens.

"Still preferably, in the light source apparatus according to the present invention, a light source section with a narrow light distribution angle and a light source section with a broad light distribution angle are alternately arranged when a plurality of the light source sections are arranged in a matrix in a row direction and a column direction in a plane view.

"Still preferably, in the light source apparatus according to the present invention, the light emitting element module comprising the one or the plurality of light source sections with the narrow light distribution angle, and the light emitting element module comprising the one or the plurality of light source sections with the broad light distribution angle are alternately arranged.

"Still preferably, in the light source apparatus according to the present invention, the light source section with the narrow light distribution angle and the light source section with the broad light distribution angle are alternately arranged in the light emitting element module.

"Still preferably, in the light source apparatus according to the present invention, the light source section comprises the light emitting element and the lens mounted for each light emitting element; and the light source section with the narrow light distribution angle and the light source section with the broad light distribution angle are formed by the difference in at least any of a length of a plurality of principal pillars of the lens, a thickness of the lens and a shape of the lens.

"Still preferably, in the light source apparatus according to the present invention, the light source section comprises the light emitting element; and the light source section with the narrow light distribution angle and the light source section with the broad light distribution angle are formed by the difference in a height of the one or the plurality of light emitting sections of the light emitting element.

"Still preferably, in the light source apparatus according to the present invention, the light source section comprises the light emitting element; and the light source section with the narrow light distribution angle and the light source section with the broad light distribution angle are formed by the difference in a shape of a sealing section through which light from the light emitting element is emitted.

"A liquid crystal display apparatus according to the present invention comprises the light source apparatus according to the present invention provided on a back surface side of a liquid crystal panel, to be used as a backlight, thereby achieving the objective described above.

"With the above structure, the operation of the present invention will be described.

"According to the present invention, in a light source apparatus in which a plurality of light emitting element modules having one or a plurality of light emitting elements mounted on a substrate are provided for planar light irradiation, when a plurality of light source sections are arranged in a matrix and in row and column directions in a plane view, a light source section with a narrow light distribution property and a light source section with a broad light distribution property are alternately arranged for each row or each column.

"Accordingly, the light source section with a narrow light distribution property and the light source section with a broad light distribution property are alternately arranged, Thus, a light source section having large light emission brightness on an optical axis passing through a light emitting element and small light emission brightness in a peripheral part away from the optical axis, is combined with a light source section having small light emission brightness on the optical axis passing through the light emitting element than the light emission brightness on the optical axis at the first light source section, and having large light emission brightness in a peripheral part away from the optical axis than light emission brightness at the peripheral part away from the optical axis of the first light source section, thereby relieving the decrease in emission brightness between the light source sections. As a result, the difference in brightness is relieved immediately above the light source section and between the light source sections. Thereby, it becomes possible to control the brightness unevenness of the plane light source and increase a display quality of the plane light source.

"In addition, since the difference in brightness is relieved immediately above the light source section and between the light source sections and the unevenness in brightness is controlled on a screen, a pitch between the light emitting elements can be widened, and as a result, the number of light source sections, including light emitting elements, are reduced.

"Effects of the Invention

"From the foregoing, according to the present invention, a light source section having large light emission brightness on an optical axis passing through a light emitting element and small light emission brightness in a peripheral part away from the optical axis, is combined with a light source section having small light emission brightness on the optical axis passing through the light emitting element than the light emission brightness on the optical axis at the first light source section, and having large light emission brightness in a peripheral part away from the optical axis than light emission brightness at the peripheral part away from the optical axis of the first light source section, thereby relieving the decrease in emission brightness between the light source sections. As a result, the difference in brightness is relieved immediately above the light source section and between the light source sections, and it becomes possible to control unevenness in brightness on a screen visually sensed by humans. As a result, it becomes possible to increase a display quality of the plane light source.

"As such, since the difference in brightness is relieved immediately above the light source section and between the light source sections and the unevenness in brightness is controlled on a screen, the pitch between the light emitting elements can be widened, and as a result, the numbers of light source sections can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is a plane view schematically showing an example of an LED module arrangement of an LED light source apparatus according to Embodiment 1 of the present invention.

"FIG. 2 is a longitudinal cross sectional view of a section AA' schematically showing a configuration example of an essential part of a liquid crystal display apparatus with the LED light source apparatus in FIG. 1 incorporated therein and is also a figure showing brightness according to positions corresponding to the section AA'.

"FIG. 3 is a plane view schematically showing positions of light diffusing lenses and light and dark portions of brightness, in the case of providing only an LED module in which brightness is set to be low by a reflection rate of a white resist.

"FIG. 4 is a plane view schematically showing positions of light diffusing lenses and light and dark portions of brightness, in the case of providing only an LED module in which brightness is set to be high by a reflection rate of a white resist.

"FIG. 5 is a plane view schematically showing positions of light diffusing lenses and light and dark portions of brightness in the case of Embodiment 1 alternately arranging an LED module having a high brightness peak and a larger difference in light and dark contrast, and an LED module having a low brightness peak and a small difference in light and dark contrast, in units of substrate section.

"FIG. 6 is a plane view schematically showing an arrangement example of three LED modules in the LED light source apparatus in FIG. 1.

"FIG. 7 is a partial longitudinal cross sectional view schematically showing a configuration example of an essential part of a liquid crystal display apparatus having an LED light source apparatus according to Embodiment 2 of the present invention incorporated therein, and is also a figure showing brightness according to positions corresponding to the subject cross-section.

"FIG. 8 is a partial longitudinal cross sectional view schematically showing a configuration example of an essential part of a liquid crystal display apparatus, for describing a light source section with a narrow light distribution angle.

"FIG. 9 is a partial longitudinal cross sectional view schematically showing a configuration example of an essential part of a liquid crystal display apparatus, for describing a light source section with a broad light distribution angle.

"FIG. 10(a) is a partial longitudinal cross sectional view of a liquid crystal display apparatus having a variation of an LED light source apparatus according to Embodiment 2 of the present invention incorporated therein; FIG. 10(b) is side view of an LED in the case of a height d1 of a light emitting section within the LED; and FIG. 10 is a side view of an LED in the case of a height d2 of a light emitting section which is lower than a height d1 of the light emitting section in FIG. 10(b)

"FIG. 11 is a longitudinal cross sectional view showing a configuration example of an essential part of a conventional light emitting element module having a light emitting element disclosed in Patent Document 1 mounted thereon.

"FIG. 12 is a plane view showing an arrangement example of optical lenses in a plane light emitting unit having a plurality of light emitting element modules of FIG. 11 mounted thereon."

For more information, see this patent application: Takasi, Motoki; Takemura, Hideo. Light Source Apparatus and Liquid Crystal Display Apparatus. Filed May 18, 2012 and posted April 24, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4463&p=90&f=G&l=50&d=PG01&S1=20140417.PD.&OS=PD/20140417&RS=PD/20140417

Keywords for this news article include: Sharp Kabushiki Kaisha.

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Source: Politics & Government Week