JP5315802B2 - Illumination device and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system capable of reducing a sharp luminance variation at boundary portions between divided regions different in emission luminance without the need for electric control. <P>SOLUTION: In the lighting system, a region on a light-emitting element substrate 12 where a plurality of light-emitting elements 10 are aligned and mounted in two axial directions is parted into the plurality of divided regions each including the plurality of light-emitting elements 10 and the emission luminance is controlled in the divided regions. The adjacent divided regions are combined into a mutually symmetrical nest structure using the region corresponding to at least one light-emitting element 10, as a nest, thereby: reducing a sharp luminance variation at the boundary portions between the divided regions different in emission luminance; and suppressing the influences of black flares or parallax. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an illumination device and a display device used for a display device such as a liquid crystal display.

  A liquid crystal display is used as a thin display device. In the liquid crystal display, a backlight that irradiates the entire surface of the liquid crystal panel from behind is used, and the liquid crystal display can be roughly classified into a direct type and an edge light type depending on the structure. In the edge light system, light is incident from the side surface of the light guide plate, and uniform light is emitted from the upper surface of the light guide plate to the liquid crystal panel. As the display becomes larger, the entire panel can be illuminated uniformly and with high brightness. There was a disadvantage that it was not possible. Therefore, the backlight of the current large display obtains desired characteristics by arranging a plurality of fluorescent lamps.

  In recent years, the use of light-emitting diodes as a light source has been attracting attention in order to further reduce the thickness, weight, lifetime, and environmental burden of large display backlights, and to improve video characteristics by controlling blinking. Yes. In a backlight using such a light emitting diode, when trying to illuminate the liquid crystal panel by emitting white light, the following two methods can be mentioned.

  The first method is a method using three light emitting diodes of RGB, and synthesizes white light by simultaneously lighting the light emitting diodes of three colors of RGB. The second method is a method using a blue light emitting diode chip as a light emitting element. In this method, the blue light-emitting diode chip is surrounded by a resin containing a phosphor, and the blue light from the blue light-emitting diode chip is color-converted into white light.

  In recent years, a method for controlling the light emission luminance of the entire backlight based on display luminance information of the entire display screen has been proposed. Furthermore, the display screen is divided into a plurality of areas (hereinafter referred to as “divided areas”) corresponding to each light source constituting the backlight, and the display luminance required for each divided area is determined. A method of partially suppressing the light emission luminance of the light source has been proposed (for example, see Patent Document 1).

  FIG. 10 conceptually shows an example of a method for controlling the light emission luminance of the backlight in units of divided areas as described above. For example, as shown in FIG. 10A, it is assumed that the brightest oval shape 61 is displayed in the substantially central portion, and an image 52 whose periphery is dark is displayed. If the backlight of the liquid crystal display device on which such an image 62 is displayed is composed of a plurality of divided regions 11 arranged vertically and horizontally as shown in FIG. 10B, FIG. When the image 61 shown in (A) is displayed, as shown in FIG. 10 (C), the light emission luminance of the divided region corresponding to the place with the lowest display luminance is suppressed. Here, reference numerals 11-10 and 11-11 denote divided regions that do not suppress the emission luminance, and the emission luminances of the divided regions other than these divided regions 11-10 and 11-11 are suppressed. Thus, by displaying the image while partially suppressing the light emission luminance of the backlight, it is possible to prevent unnecessary lighting of the backlight and reduce power consumption.

  However, in the method of controlling the light emission luminance of the backlight in units of divided areas as described above, a steep luminance change occurs at a boundary portion between divided regions having different light emission luminances. FIG. 11 shows an example of a luminance distribution including a steep luminance change at a boundary portion between divided regions having different light emission luminances. Here, 11-A is a divided region with the maximum luminance, and 11-B is a divided region in the extinguished state around the divided region 11-A with the maximum luminance. In this case, the luminance distribution at the boundary between the divided region 11-A having the maximum luminance and the surrounding divided region 11-B in the lighted state suddenly changes from the equivalent value in the lighted state to the maximum luminance value. This caused the following problems, for example.

  In FIG. 11, when the bright portion 63 in the display image occupies a part of the divided area 11-A, the divided area 11-A is given a high luminance value such as the maximum luminance, while the divided area 11-A. The divided area 11-B around the area is turned off or given a low luminance value in accordance with a dark image. From this, although the portion other than the bright portion 63 in the divided region 11-A should originally appear darker than the surrounding divided region 11-B, it is more than the surrounding divided region 11-B. A “black flare” that appears to float up occurs.

  In addition, the problem of luminance difference due to parallax also increases. FIG. 12 is a diagram showing the relationship between the luminance distribution and the luminance difference due to parallax. Here, the luminance difference due to parallax is a difference in luminance between when the surface of the liquid crystal panel is viewed from the front and when viewed from the non-front. For example, the brightness of point A on the surface of the liquid crystal panel is greatly different between when viewed from the front and when viewed from the non-front, and this phenomenon is compared with the case where the brightness change is slow as shown by the dotted line in the figure. Become prominent.

In order to reduce the influence of such black flare and parallax, for example, the following method has been proposed. That is, according to the image signal to the liquid crystal display panel, the luminance of the light source is controlled for each divided area, and when the lighting area and the unlit area where the luminance of the backlight is determined based on the image signal are adjacent to each other, This is a method of lighting an adjacent area of a certain width near the lighting area of the extinguishing area with a lower luminance than the lighting area. In this method, since the luminance change between the divided areas becomes gentle, the influence of black flare and parallax can be alleviated (see, for example, Patent Document 2).
JP 2004-221503 A JP 2008-51905 A

  However, in such a known method, a process for detecting a portion where the luminance difference between the lighting region and the non-lighting region is equal to or larger than the set value, or a luminance value of an adjacent region having a certain width of the detected non-lighting region is equal to or smaller than the set value. A logic circuit or software for performing a lifting process is required. For this reason, the scale of the circuit and the scale of the software increase, and the scale further increases as the display becomes larger.

  The present invention has been made in view of the above points, and an illuminating device capable of alleviating a steep luminance change at a boundary portion between divided regions having different emission luminances without using electrical control, and the same It is to provide a display device using the above.

  In solving the above-described problems, the lighting device of the present invention includes a substrate, a plurality of light-emitting elements arranged in a biaxial direction in a predetermined region of the substrate, and a plurality of predetermined regions of the substrate. A plurality of divided regions including the light emitting element, and a control unit that controls light emission luminance for each of the divided regions, wherein at least a part of the divided regions adjacent to each other has at least one light emission. They are combined with each other in a nested structure in which regions corresponding to elements are nested.

  In the present invention, at least a part of the divided regions adjacent to each other is combined with each other in a nested structure with the region including at least one light emitting element as a nest, so that the boundary portion between the divided regions having different light emission luminances. A steep luminance change can be mitigated, and the influence of black flare and parallax can be suppressed.

  In the illuminating device of the present invention, the adjacent divided regions may be combined in a nesting structure symmetrical to each other. Thereby, a steep luminance change at the boundary portion between the divided regions having different emission luminances can be alleviated uniformly.

  In the illuminating device of the present invention, the at least some of the adjacent divided regions may be combined in a symmetric nested structure with a plurality of regions having different numbers of light emitting elements as individual nesting. Thereby, the luminance change at the boundary portion between the divided regions having different emission luminances can be made more gradual.

  Furthermore, a display device according to another aspect of the present invention includes a display panel and a lighting device provided adjacent to the display panel, and the lighting device is provided in a predetermined area of the substrate and the substrate. A plurality of light emitting elements arranged in the axial direction and a predetermined area of the substrate are divided into a plurality of divided areas each including the plurality of light emitting elements, and the light emission luminance for each of the divided areas is controlled. And at least a part of the divided regions adjacent to each other are combined with each other in a nested structure in which a region corresponding to at least one of the light emitting elements is nested.

  As described above, according to the present invention, it is possible to alleviate a steep luminance change at a boundary portion between divided regions having different emission luminances without using electrical control, and suppress the influence of black flare and parallax. it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the form described below, a display device including the lighting device of the present invention is applied to a liquid crystal television.

  Note that the scope of application of the display device of the present invention is not limited to a liquid crystal television, and any display device including a lighting device may be used. For example, it can be widely applied to personal computers, PDAs (Personal Digital Assistants), and the like.

  FIG. 1 is a schematic perspective view of a liquid crystal television 100 as a display device according to an embodiment of the present invention, and FIG. 2 is a schematic exploded perspective view of a portion held by a casing 300 of the liquid crystal television 100. As shown in these drawings, the liquid crystal television 100 includes a liquid crystal panel 200 as a display panel, the lighting device 1, a driving unit 420 that drives the liquid crystal panel 200 and the lighting device 1, a liquid crystal panel 200, the lighting device 1, and A housing 300 that holds the driving unit 420 and a stand 400 that holds the housing 300 are provided. The illumination device 1 illuminates the image display area of the liquid crystal panel 200 from the back, and emits white light.

  Below, the illuminating device which is embodiment of this invention is demonstrated.

(First embodiment)
FIG. 3 is a cross-sectional view of the illumination device 1 according to the first embodiment of the present invention. As shown in the figure, the lighting device 1 includes a rectangular light emitting element substrate 12, a reflector 13, a rectangular light diffusion plate 15 corresponding to the planar shape of the light emitting element substrate 12, and a plane of the light emitting element substrate 12. And a rectangular fluorescent sheet 16 corresponding to the shape. A plurality of light emitting elements 10 are mounted on the light emitting element substrate 12 in a predetermined rectangular area of the light emitting element substrate 12 so as to be arranged in a matrix in each of the two axial directions of the rectangular area. The light diffusing plate 15 is disposed with a distance of, for example, about 20 mm from the light emitting element substrate 12, and the gap is held by a plurality of support pillars (not shown). For example, the fluorescent sheet 16 is disposed on the light diffusing plate 15 on the light exit surface side of the light diffusing plate 15, for example, so as to overlap or be close to the light diffusing plate 15. A liquid crystal panel 200 is disposed at the tip of the light emission surface of the fluorescent sheet 16. The reflection plate 13 is disposed on the inner surface in four directions of the cubic space formed by the light emitting element substrate 12 and the light diffusion plate 15. A liquid crystal panel 200 is disposed at the tip of the light emission surface of the fluorescent sheet 16.

  The light emitting element substrate 12 includes a metal substrate 17 and a plurality of light emitting elements 10 mounted on one surface of the substrate 17 via an insulating layer (not shown). Here, for example, an InGaN-based blue light emitting diode is used as the light emitting element 10.

  FIG. 4 is a cross-sectional view showing details of a blue light emitting diode package. As shown in the figure, a submount substrate 26 on which a blue light emitting diode chip 25 is surface-mounted is formed on a surface of an insulating layer 18 provided on one surface of a metal substrate 17 by a heat conductive adhesive 27. It is joined. An electrode portion (not shown) provided on the submount substrate 26 is electrically connected to the electrode portion 19 on the substrate 17 side by a bonding wire 20. And the chip | tip 25 of a blue light emitting diode is sealed by the transparent resin molding 28 as a lens body including the area | region to the connection part by the bonding wire 20 of the periphery vicinity. Examples of the resin material for sealing include silicone and the like which are excellent in light resistance and heat resistance.

  For example, the fluorescent sheet 16 is excited on a transparent plastic film by a green phosphor that emits green light having a green wavelength by being excited by blue light having a blue wavelength emitted from a blue light emitting diode. Two types of phosphors are included: a red phosphor that emits red light having a red wavelength. Thereby, the green light and the red light color-converted by the fluorescent sheet 16 and the blue light that is the excitation light from the blue light emitting diode are mixed, and white light is generated and emitted. The fluorescent sheet 16 includes a transparent plastic film containing a yellow phosphor that emits yellow light having a yellow wavelength when excited by blue light having a blue wavelength emitted from a blue light emitting diode. May be. In this case, white light is obtained by mixing the yellow light color-converted by the fluorescent sheet 16 and the blue light.

  Further, a purple (near ultraviolet) light emitting diode can be used instead of the blue light emitting diode. In this case, as a phosphor layer, a red phosphor that emits red light of red wavelength when excited by violet (near ultraviolet) light of violet (near ultraviolet) wavelength emitted from a violet (near ultraviolet) light emitting diode; Contains a green phosphor that emits green light of green wavelength when excited by violet (near ultraviolet) light and a blue phosphor that emits blue light of blue wavelength when excited by violet (near ultraviolet) light Things are used. Thereby, red, green, and blue color-converted by the phosphor layer and violet (near ultraviolet) light are mixed to obtain white light.

As the material of the phosphor for yellow, (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce ³⁺ (common name: YAG: Ce ³⁺ ), α-SiAlON: Eu ²⁺ , (Ca, Sr, Ba) ) ₃ SiO ₄ : Eu ^{2+ and the} like. Examples of the green phosphor material include (Ca, Sr, Ba) ₃ SiO ₄ : Eu ²⁺ , SrGa ₂ S ₄ : Eu ²⁺ , β-SiAlON: Eu ²⁺ , Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce ³⁺ , and phosphor materials for red are (Ca, Sr, Ba) S: Eu ²⁺ , (Ca, Sr, Ba) ₂ SiO ₅ N ₈ : Eu ²⁺ , CaAlSiN ₃ : Eu ^{2+ and the} like.

  FIG. 5 is a plan view of the light emitting side of the light emitting element substrate 12. In the light emitting element substrate 12, for example, a total of 1020 light emitting elements 10 are arranged at regular intervals of 30 rows and 34 columns. The entire rectangular area in which these light emitting elements 10 are arranged is divided into a plurality of types of divided areas 11 (11a, 11b, 11c), and a plurality of pieces belonging to each divided area 11 (11a, 11b, 11c). The group of the light emitting elements 10 is a unit for controlling the light emission luminance. In the example of FIG. 5, the entire rectangular area is divided into a total of 42 divided areas 11 (11 a, 11 b, 11 c) of 6 vertical and 7 horizontal. In this embodiment, a light source module corresponding to each divided region 11 (11a, 11b, 11c) is produced, and these light source modules are combined to constitute one rectangular light source corresponding to the liquid crystal panel 200. Hereinafter, the divided area 11 will be referred to as the light source module 11 and the description will proceed. Each light source module 11 is connected to the drive unit 420 (FIG. 2) through a flexible printed board (not shown). The drive unit 420 includes a control unit that controls light emission luminance in units of the light source module 11.

  In order to fill the entire rectangular area with the light source module 11 without gaps, in this embodiment, as shown in FIG. 5, three types of light source modules 11a, 11b, and 11c are used. Hereinafter, 11a is referred to as a “first light source module”, 11b as a “second light source module”, and 11c as a “third light source module”. The first light source module 11a is equipped with 36 light emitting elements 10 and fills other than the peripheral edge of the entire rectangular area. Therefore, most of the entire rectangular area is constituted by the combination of the first light source modules 11a. The third light source module 11c is mounted with four light emitting elements 10 to fill the four corners of the entire rectangular area. And the 2nd light source module 11b mounts the 12 light emitting elements 10, and fills except the four corners of the peripheral part of the whole rectangular area.

  Except for the combination of the second light source module 11b and the third light source module 11c arranged at the peripheral edge of the entire rectangular area, the adjacent light source modules 11 (the combination of the first light source modules 11a, the first The light source module 11a and the second light source module 11b are combined with each other in a nested structure with a region corresponding to at least one light emitting element 10 as a nest. The region of one light emitting element 10 is an area in which one light emitting element 10 is mounted in the light source module 11 as indicated by reference numeral 31 in FIG. A region 31 where the single light emitting element 10 is mounted or a region 32 where a plurality of the regions 31 are continuous is used as a nesting portion.

  FIG. 6 is an enlarged view of the combination of the first light source modules 11a by the nesting structure. Here, the left first light source module 11a is turned off, and the right first light source module 11a is turned on. Here, paying attention to the number of light-emitting elements 10 in the lit state from the Nth column to the (N + 2) th column, the number is 2 in the Nth column, 4 in the (N + 1) th column, and the (N + 2) th column. There are six light-emitting elements 10 that are lit. On the other hand, when attention is paid to the number of light-emitting elements 10 in the unlit state from the (N−1) th column to the (N + 1) th column, there are 6 in the (N−1) th column, 4 in the Nth column, and In the (N + 1) -th column, there are two light-emitting elements 10 that are turned off. Thus, the first light source modules 11a are combined in a nesting structure symmetrical to each other with the region 31 and the region 32 being nested.

  FIG. 7 is a diagram showing a luminance distribution when the light emitting elements 10 in the Mth row and the (M + 1) th row are caused to emit light in the combination of the first light source modules 11a in the nested structure in FIG. Here, 41 is a luminance distribution of the Mth row, 42 is a luminance distribution of the (M + 1) th row, and 43 is a luminance distribution obtained by combining the luminance distribution 41 of the Mth row and the luminance distribution 42 of the (M + 1) th row. . In the luminance distribution of 43, the dotted line is the luminance distribution when the light source module under the same conditions is used except that it does not have a nested structure. 43, by combining the first light source modules 11a with each other in a nested structure, it is possible to alleviate a steep luminance change at a boundary portion between divided regions having different emission luminances. The influence of flare and parallax can be suppressed.

  Furthermore, in this embodiment, since the shape (layout of the light emitting element 10) of the first light source modules 11a is determined so that adjacent ones are combined with each other in a symmetrical nested structure, the light source is turned off in FIG. The same effect can be obtained even when the left and right first light source modules 11a are interchanged. That is, it is possible to alleviate the luminance change at the boundary portion between the divided regions having different emission luminances uniformly in all the regions.

  Further, in this embodiment, the light source module 11 is provided with a region 31 in which one light emitting element 10 is mounted and a region 32 in which a plurality of regions 31 are continuous in the light source module 11, so that only one size of nesting is provided. Compared to the case where it is adopted, the luminance change at the boundary portion between the divided regions having different emission luminances can be made more gradual. Of course, nesting in which the number of the light emitting elements 10 is three or more may be added.

  Furthermore, in this embodiment, it is possible to alleviate a steep luminance change at the boundary portion between the divided regions having different emission luminances without using electrical control, and thus the size can be reduced. In addition, power consumption can be reduced.

(Modification 1)
Next, the modification 1 of this embodiment is shown.
FIG. 8 is a plan view of the light emitting side of the light emitting element substrate 12 of Modification 1 of the present embodiment.

  The main difference from the light emitting element substrate 12 shown in FIG. 5 is the number and layout of the light emitting elements 10 mounted on each of the first light source module 11a and the second light source module 11b. Sixteen light emitting elements 10 are mounted on the first light source module 11a. Eight light emitting elements 10 are mounted on the second light source module 11b. And also in this modification 1, except for the combination of the 2nd light source module 11b and the 3rd light source module 11c which are arrange | positioned at the peripheral part of the whole rectangular area, the adjacent light source modules 11 (1st The combination of the light source modules 11a and the combination of the first light source module 11a and the second light source module 11b) are combined with each other in a nested structure with a region corresponding to at least one light emitting element 10 as a nest. Therefore, also according to the first modification, it is possible to alleviate a steep luminance change at a boundary portion between divided regions having different emission luminances, and it is possible to suppress the influence of black flare and parallax.

  Further, in the first modification, since the first light source modules 11a are combined with each other in a nesting structure in which adjacent ones are symmetrical to each other, the boundary portion between the divided regions having different emission luminances uniformly in all regions It is possible to alleviate a steep luminance change at.

  Furthermore, also in this modified example 1, by providing the light source module 11 with a region 31 in which one light emitting element 10 is mounted and a region 32 in which a plurality of regions 31 are continuous as a nest, only one size of nest is provided. As compared with the case of adopting, the luminance change at the boundary portion between the divided regions having different emission luminances can be made more gradual.

(Modification 2)
Next, a second modification of the present embodiment is shown.
FIG. 9 is a diagram showing a configuration of the first light source module 11a of Modification 2 of the present embodiment.

  The second modification is an example in which only the region 31 in which one light emitting element 10 is mounted is provided as a nest in the first light source module 11a. As described above, even when adjacent light source modules are combined with each other in a nested structure with only the region 31 on which one light emitting element 10 is mounted as a nest, the steepness at the boundary portion between the divided regions having different emission luminances can be obtained. Brightness change can be mitigated, and the influence of black flare and parallax can be suppressed.

(Other variations)
In the above embodiment, the diffusion plate is used as the light diffusion means. However, a film having the same light diffusion function may be used instead of the diffusion plate. Further, the fluorescent sheet and the light diffusing means are not necessarily in close contact with each other, and a gap portion may exist between both members. Furthermore, in the above-described embodiment, the light source modules for each divided region are produced and combined, but the plurality of light emitting element groups belonging to each divided region is configured to be a unit in which the light emission luminance is controlled. It is not necessary to use what is modularized. Further, although an embodiment using a blue light emitting diode as a light emitting element has been described here, the present invention can also be applied to a case where light emitting diodes of three colors of RGB are used.

  The present invention is not limited only to the above-described embodiment, and it is needless to say that various updates can be added without departing from the gist of the present invention.

1 is a schematic perspective view of a liquid crystal television as a display device according to an embodiment of the present invention. FIG. 2 is a schematic exploded perspective view of a portion held by a case of the liquid crystal television of FIG. 1. It is sectional drawing of the illuminating device concerning the 1st Embodiment of this invention. It is sectional drawing which shows the detail of the package of a blue light emitting diode. It is a top view of the light emission side of a light emitting element substrate. It is an enlarged view of the combination by the nesting structure of the 1st light source modules. It is a figure which shows the luminance distribution at the time of making the light emitting element of M line and (M + 1) line light-emit in the combination by the nesting structure of the 1st light source modules of FIG. It is a top view by the side of the light emission of the light emitting element substrate of the modification 1 of this embodiment. It is a figure which shows the structure of the 1st light source module of the modification 2 of this embodiment. It is a conceptual diagram of the method of controlling the light emission brightness | luminance of a backlight in the unit of a division area. It is a figure which shows the luminance distribution by the control method of FIG. 10, and a problem by this. It is the figure which showed the relationship between luminance distribution and the luminance difference by parallax.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Illuminating device 10 Light emitting element 11 Divided area (light source module)
11a 1st light source module 11b 2nd light source module 11c 3rd light source module 12 Light emitting element substrate 15 Diffusion plate 16 Fluorescent sheet 17 Substrate 100 Liquid crystal television 200 Liquid crystal panel 420 Drive part

Claims (2)

A substrate,
A plurality of light emitting elements arranged in a biaxial direction in a predetermined region of the substrate;
A predetermined region of the substrate is divided into a plurality of divided regions each including a plurality of the light emitting elements, and a control unit that controls light emission luminance for each of the divided regions,
An illuminating device in which at least some of the divided regions adjacent to each other are combined with each other in a nesting structure symmetrical to each other with a plurality of regions having different areas and the number of the light emitting elements as individual nesting . Comprising a display panel and an illumination device provided adjacent to the display panel, the illumination device comprising:
A substrate,
A plurality of light emitting elements arranged in a biaxial direction in a predetermined region of the substrate;
A predetermined region of the substrate is divided into a plurality of divided regions each including a plurality of the light emitting elements, and a control unit that controls light emission luminance for each of the divided regions,
A display device in which at least a part of adjacent divided regions occupy a plurality of regions having different areas and the number of light emitting elements are combined into each other in a nesting structure symmetrical to each other.

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