Planar illumination device

Abstract

A planar illumination device (1) according to an embodiment comprises a substrate (3), a plurality of light sources (4) in a first group, and one or more light sources (5) in a second group. Prescribed electrical wiring is applied to the substrate (3). The plurality of light sources (4) in the first group are disposed across substantially the entire surface of the substrate (3). The one or more light sources (5) in the second group are disposed adjacent to the plurality of light sources (4) in the first group within a prescribed region on the substrate (3).

Description

Planar lighting device

[0001] The present invention relates to a surface lighting device.

[0002] There are cluster meters that combine various meters required when driving, such as an automobile speedometer, tachometer, and odometer (see, for example, Patent Document 1). Such cluster meters include telltale parts such as warning lights, and the telltale parts are required by law to have specified colors and be visible in any environment, such as by not being insufficiently bright even when exposed to direct sunlight.

[0003] Nowadays, such cluster meters have come to use LCD panels and backlights to provide a high degree of display flexibility, but because the telltale section requires high brightness and high color rendering, it is often installed separately from the LCD panel. In other words, the telltale section is comprised of a light-blocking member cut out in the shape of the icon to be displayed, and a single-color LED (Light Emitting Diode) that corresponds to the specified display color and is located directly below the light-blocking member.

[0004] Although not the telltale part of a cluster meter itself, a display device provided with a different backlight has been disclosed for displaying fixed patterns such as touch switch patterns alongside non-fixed patterns such as map information and in-vehicle camera images (see, for example, Patent Document 2). Alternatively, a warning display for approaching vehicles may be provided independently to the rear, but door mirrors and room rearview mirrors are also increasingly being displayed using liquid crystal panels and backlights, and telltale parts such as approach warning displays may also be provided within the display device.

[0005] Japanese Patent Laid-Open No. 9-301065 Japanese Patent Laid-Open No. 2019-152748

[0006] As described above, if the telltale section of the cluster meter is provided separately from the liquid crystal panel and its backlight for the other sections, or if the telltale sections of the door mirrors and rearview mirror are provided separately from the liquid crystal panel and its backlight for the other sections, the structure becomes complex and it becomes difficult to reduce costs.In addition, because the telltale section cannot be used for other displays, there are problems in that the display screen is not fully utilized and the degree of freedom in screen display is not increased.

[0007] The present invention has been made in view of the above, and aims to provide a surface lighting device that can be used as a backlight for cluster meters, door mirrors, rearview mirrors, etc. that have telltale sections, that can meet the high brightness and high color rendering properties required for telltale sections, etc., that has a simple structure, that makes effective use of the display screen, and that allows for increased flexibility in screen display.

[0008] In order to solve the above-mentioned problems and achieve the object, a surface lighting device according to one aspect of the present invention includes a substrate, a first group of multiple light sources, and one or more second group of light sources. The substrate is provided with predetermined electrical wiring. The first group of multiple light sources is arranged over substantially the entire surface of the substrate. The second group of one or more light sources is arranged adjacent to the first group of multiple light sources within a predetermined region of the substrate.

[0009] A surface lighting device according to one embodiment of the present invention can be used as a backlight for cluster meters, door mirrors, rearview mirrors, etc. that have telltale sections, and can meet the high brightness and high color rendering properties required for telltale sections, etc., has a simple structure, makes effective use of the display screen, and improves the flexibility of screen display.

[0010] FIG. 1 is an external perspective view of a surface lighting device according to one embodiment. FIG. 2 is an exploded perspective view of the main parts of the surface lighting device. FIG. 3 is a plan view showing only the substrate and the reflector. FIG. 4 is a cross-sectional view taken along the line X-X of the surface lighting device in FIG. 1. FIG. 5 is a diagram showing an example of the effect on brightness uniformity and the improvement thereof due to the addition of a second group of light sources and the removal of a portion of the reflecting wall of the reflector. FIG. 6 is an external perspective view showing an example of a state in which a liquid crystal panel is attached to a surface lighting device. FIG. 7 is a diagram showing an example of a telltale portion displayed on the liquid crystal panel.

[0011] Hereinafter, a surface lighting device according to an embodiment will be described with reference to the drawings. Note that the present invention is not limited to these embodiments. Furthermore, the dimensional relationships and ratios of elements in the drawings may differ from reality. The dimensional relationships and ratios may differ between the drawings. Furthermore, the content described in one embodiment or modification is, in principle, applicable to other embodiments or modifications as well.

[0012] FIG. 1 is an external perspective view of a surface lighting device 1 according to one embodiment. In the figure, for convenience, the longitudinal direction of the surface lighting device 1 is designated as the X-axis direction, the lateral direction as the Y-axis direction, and the thickness direction as the Z-axis direction, but the position during use is arbitrary. FIG. 2 is an exploded perspective view of the main parts of the surface lighting device 1, and is a view seen from the light output surface side, similar to FIG. 1. FIG. 3 is a plan view showing only the substrate 3 and the reflector 6. FIG. 4 is an X-X cross-sectional view of the surface lighting device 1 in FIG. 1, showing a cross-section of the upper part of FIG. 1.

[0013] 1, the surface lighting device 1 has a substantially rectangular (or substantially square) and plate-like outer shape, and the housing is composed of a bottom frame (hidden behind in FIG. 1) in the shape of a box with a floor that houses a substrate and the like (described later), and a top frame 10 that covers the opening side of the bottom frame. The top frame 10 has an exit surface 1a formed by a substantially rectangular opening 10a, so that light is irradiated from the inside of the surface lighting device 1 to the outside. In FIG. 1, an internal polarized reflective film 9 is exposed on the exit surface 1a. When the surface lighting device 1 is used as a backlight for an in-vehicle cluster meter, door mirror, rearview mirror, etc., a liquid crystal panel or the like is attached to the side of the exit surface 1a.

[0014] In Figure 2, the surface lighting device 1 comprises a bottom frame 2, a substrate 3 on which a first group of multiple (large number) light sources 4 and a second group of one or more (six in the illustrated example) light sources 5 are arranged, a reflector 6, a diffuser 7, a prism sheet 8, and a polarized reflective film 9 are attached, and a top frame 10 fits onto the outside of the bottom frame 2 to form a lid.

[0015] The bottom frame 2 has a bottom and four side walls provided around the periphery of the bottom. The bottom frame 2 is formed by die-casting, sheet metal, etc. The substrate 3 is fixed to the inside of the bottom of the bottom frame 2 via a fixing member (not shown) such as double-sided tape.

[0016] A first group of light sources 4, each consisting of a plurality (numerous) of LEDs (Light Emitting Diodes) or the like, is arranged, for example, in a grid pattern across substantially the entire surface of the substrate 3. Furthermore, in a predetermined region on the substrate 3, for example, along a portion of the upper long side in the figure, one or more second group of light sources 5 are arranged adjacent to the first group of light sources 4. Each second group of light source 5 is arranged, for example, in the center of four first group of light sources 4 arranged at each corner of an imaginary rectangle (without interfering with the first group of light sources 4). Electrical wiring is provided on the substrate 3 to supply power to each of the light sources 4, 5. The light emission of each of the light sources 4, 5 can be individually controlled.

[0017] The back surface of the reflector 6 is fixed between the first group of light sources 4 on the substrate 3 via a plurality of fixing members (not shown) such as double-sided tape in the shape of strips extending in the left-right direction (or the up-down direction) in FIG.

[0018] The reflector 6 reflects light emitted from the first group of light sources 4 toward the light output surface to increase brightness. The reflector 6 has an outer edge surrounded by a frame 6a that also serves as a reflective wall, and its interior is divided into multiple (numerous) segments surrounded by four reflective walls 6b. Most of the reflector 6 is made up of segments (first segments) corresponding to individual first group light sources 4, while the portion corresponding to a telltale portion of a warning light or the like is made up of a segment corresponding to four first group light sources 4 arranged vertically and horizontally and one central second group light source 5. In the segment (second segment) corresponding to the telltale portion, the four reflective walls 6b between the four first group light sources 4 are removed, and the second group light source 5 is placed in the space formed by removing the four reflective walls 6b. As a result, the four first group light sources 4 and the central second group light source 5 are surrounded by four reflective walls 6b (one of which is part of the frame 6a). The reflector 6 is manufactured by injection molding of synthetic resin or the like. In the above embodiment, the four reflecting walls 6b are entirely removed, but a portion of each of the four reflecting walls 6b may remain as long as space for arranging the second group of light sources 5 can be secured. The second segments may be arranged at any position. For example, a first segment may be interposed between adjacent second segments, or the second segments may be provided at a position away from the frame 6a and inward. If the overall shape of the reflector 6 is irregular in plan view, the second segments may be provided only in the rectangular portion excluding the irregular portion. Furthermore, multiple second segments may correspond to one icon.

[0019] The first group of light sources 4 are elements that emit light from the side surfaces, while the second group of light sources 5 are elements that emit light from the top surface. That is, light emitted from the side surfaces of the first group of light sources 4 is reflected by the reflecting wall 6b of the reflector 6 and emitted in a direction approximately normal to the emission surface. Light emitted from the top surface of the second group of light sources 5 is emitted directly in a direction approximately normal to the emission surface.

[0020] The diffuser 7, which is disposed on the exit side of the reflector 6, diffuses the light passing through it to reduce brightness unevenness. The incident side of the diffuser 7 (the light source 4, 5 side, the reflector 6 side) is provided with a plurality of tiny pyramid prisms, each with a quadrangular pyramid whose apex (the apex that does not contact the base) faces the light sources 4, 5 and whose bottom faces the exit side. The pyramid prisms may be disposed over the entire surface of the diffuser 7, or may be disposed only in an area where the second group of light sources 5, which corresponds to the telltale portion, is disposed. Separately from the diffuser 7, an optical sheet provided with a plurality of pyramid prisms may be disposed on the incident side of the diffuser 7.

[0021] The pyramidal prisms diffuse light emitted from the side surfaces of the first group of light sources 4 and reflected by the reflecting walls 6b of the reflector 6, as well as light emitted from the top surfaces of the second group of light sources 5, to the surrounding area, thereby reducing uneven brightness. Note that the diffuser 7 does not necessarily need to include pyramidal prisms depending on the specifications for brightness uniformity, and prisms of other shapes than pyramidal ones may also be provided.

[0022] The prism sheet 8 disposed on the exit side of the diffuser 7 adjusts the light distribution to improve brightness.

[0023] The polarized reflection film 9 arranged on the output side of the prism sheet 8 passes polarized light in a predetermined direction and reflects polarized light in a direction perpendicular to that, and is aligned with the polarization direction of the liquid crystal panel attached externally.

[0024] A top frame 10 is disposed on the light exit surface side of the polarizing reflective film 9, and is fixed to the bottom frame 2. The top frame 10 is formed by die casting, sheet metal, or the like.

[0025] Although the planar lighting device 1 is illustrated as being flat, the planar lighting device 1 may also be curved. In this case, for example, the bottom frame 2, the substrate 3, the reflector 6, and the top frame 10 are formed into curved shapes, and the diffuser 7, the prism sheet 8, and the polarizing reflective film 9 are deformed into curved shapes during assembly.

[0026] 5A and 5B are diagrams showing examples of the effects on luminance uniformity and the improvement thereof due to the addition of the second group of light sources 5 and the removal of some of the reflective walls of the reflector 6. The top diagram (a) is a plan view showing an example of the luminance distribution of the first comparative example of the surface illumination device 1′ in which the second group of light sources is not provided and some of the reflective walls of the reflector are not removed. In this case, there is a slight decrease in luminance in the periphery, but luminance uniformity is maintained in most areas.

[0027] (b) in the second row from the top is a plan view showing an example of the luminance distribution when only the first group of light sources is turned on in the surface lighting device 1" of the second comparative example, in which a second group of light sources is provided and part of the reflective wall of the reflector has been removed. In this case, uneven luminance occurs near the upper long side due to the removal of the reflective wall of the reflector, but the impact is small because the number and arrangement of the first group of light sources are the same as in the first comparative example. Note that the second comparative example, in which a second group of light sources is provided and part of the reflective wall of the reflector has been removed, is slightly inferior in luminance uniformity compared to the embodiment shown in Figures 1 to 4, but can be adopted as another embodiment.

[0028] (c) in the third row from the top is a plan view showing an example of the luminance distribution when the first and second groups of light sources are turned on in the surface lighting device 1" of the second comparative example, in which the second group of light sources is provided and part of the reflective wall of the reflector has been removed. In this case, in addition to the gentle luminance distribution in (b), a peaky luminance distribution is observed due to the lighting of the second group of light sources, and high luminance can be expected in the telltale area.

[0029] (d) in the fourth row from the top is a plan view showing an example of the luminance distribution when only the first group of light sources 4 is turned on in the surface illumination device 1 according to the embodiment of Figures 1 to 4. In this case, compared to the luminance distribution in (b), the luminance unevenness is reduced due to the diffusion effect of the pyramidal prisms of the diffuser 7.

[0030] 1 to 4 , the fifth diagram (e) is a plan view showing an example of the luminance distribution when the first group of light sources 4 and the second group of light sources 5 are turned on. In this case, compared to the luminance distribution in (c), the peaky luminance distribution is eliminated due to the diffusion effect of the pyramidal prisms of the diffuser 7. Therefore, the use of a diffuser with pyramidal prisms is effective when luminance uniformity is prioritized over brightness.

[0031] 6 is a perspective view showing an example of the appearance of the planar lighting device 1 with the liquid crystal panel 20 attached thereto. The front side in the figure is the display surface 20a of the liquid crystal panel 20. The liquid crystal panel 20 may be a color liquid crystal panel or a monochrome liquid crystal panel.

[0032] FIG. 7 shows an example of a telltale section 20b displayed on the liquid crystal panel 20. When a color liquid crystal panel is used as the liquid crystal panel 20, the first group of light sources 4 and the second group of light sources 5 can emit white or pseudo-white light. In this case, the shapes and colors of the various warning lights in the telltale section 20b are displayed as images reproduced by the color liquid crystal panel, and the various warning lights are displayed by illuminating them from behind with white or pseudo-white light from the second group of light sources 5. Furthermore, by simultaneously lighting not only the second group of light sources 5 but also the surrounding first group of light sources 4, the brightness of the warning light display can be further increased. Even when a color liquid crystal panel is used, the brightness of the warning lights can be further increased by configuring the second group of light sources 5 to emit light in a color corresponding to the displayed icon.

[0033] At least one of the first and second groups of light sources 4, 5 may be a light-emitting source that combines red, green, and blue (RGB) monochromatic LEDs. LEDs in which RGB light-emitting chips are integrated into a single package are commercially available. When the RGB light-emitting chips are turned on simultaneously, white light is obtained, and when one of the RGB light-emitting chips is turned on, monochromatic light of one of the RGB colors is obtained. By changing the ratio of the light emission amounts of the RGB chips, monochromatic light of any color can be obtained. This allows the light source elements to be standardized.

[0034] Furthermore, when a monochrome liquid crystal panel is used as the liquid crystal panel 20, the first group of light sources 4 can emit light in white, pseudo-white, or a predetermined color, and the second group of light sources 5 can emit light in a color (including white and pseudo-white) corresponding to the displayed icon. In this case, the figures of the various warning lights in the telltale section 20b are displayed as images reproduced by the monochrome liquid crystal panel, and the colors of the various warning lights are displayed by the color of illumination provided from behind by the second group of light sources 5. Note that, in this case as well, at least one of the first and second groups of light sources 4, 5 may be a light source that combines monochromatic red, green, and blue (RGB) LEDs.

[0035] Furthermore, regardless of whether a color or monochrome liquid crystal panel is used as the liquid crystal panel 20, any image (such as a speedometer, tachometer, map image, or television image) can be displayed over the entire display surface 20a, including the telltale portion 20b. In this case, illumination from the surface lighting device 1 is provided by the first group of light sources 4. Furthermore, icons corresponding to warning lights or the like can be displayed in a predetermined color in the telltale portion 20b, superimposed on the image in the other portions. To ensure the visibility of the icons, when displaying icons superimposed on various meters, the icons can be displayed with symbols on a black background, the display of the various meters in the overlapping portions can be turned off, or the telltale portion 20b and the various meters can be displayed alternately. Furthermore, when used as a cluster meter, in addition to the display of the telltale portion 20b, various meters required during driving, such as a speedometer and a tachometer, can be displayed in the portions other than the telltale portion 20b. When used as a door mirror or a rearview mirror, the telltale portion 20b can be displayed, and at the same time, a camera-captured image of the rear side or the like can be displayed in the portion other than the telltale portion 20b.

[0036] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0037] As described above, the surface illumination device according to the embodiment includes a substrate provided with predetermined electrical wiring, a first group of multiple light sources arranged over substantially the entire surface of the substrate, and one or more light sources of a second group arranged adjacent to the first group of multiple light sources within a predetermined region of the substrate. This makes it possible to use the surface illumination device as a backlight for a cluster meter, door mirror, rearview mirror, etc. that has a telltale section, and can meet the high brightness and high color rendering properties required for the telltale section, while having a simple structure, making effective use of the display screen, and improving the flexibility of the screen display.

[0038] That is, the second group of light sources is primarily used to illuminate the telltale section and the first group of light sources is used to illuminate areas other than the telltale section, and therefore the device can be used as a backlight for cluster meters, door mirrors, rearview mirrors, and the like that have telltale sections. Furthermore, because the second group of light sources is provided separately from the first group of light sources, the brightness of the second group of light sources can be easily increased and they can be made to emit any color, thereby meeting the high brightness and high color rendering properties required for telltale sections and the like. Furthermore, because the first group of light sources and the second group of light sources are arranged on a single substrate, the structure is simple and low-cost. Furthermore, because the first group of light sources allows the entire screen to be used for areas other than the telltale section, the display screen can be used effectively. Furthermore, the telltale section and other displays are displayed on a liquid crystal panel provided on the output side, eliminating the need for a light-shielding member with an icon-shaped cutout specifically for the telltale section, thereby improving the flexibility of the screen display.

[0039] Furthermore, the plurality of light sources in the first group are arranged in a lattice pattern over substantially the entire surface of the substrate, and one or more light sources in the second group are arranged between adjacent light sources in the first group. This allows the plurality of light sources in the first group to be arranged in the same manner as in conventional technology that does not have a telltale unit, and therefore allows the light sources to function as a backlight for a telltale unit or the like while maintaining their function as a backlight for a cluster meter or the like.

[0040] The light source of the second group is disposed at the center of four light sources of the first group that are adjacent vertically and horizontally, and at least a portion of the four reflective walls between the four light sources of the first group with the light source of the second group disposed at the center is removed. This makes it possible to additionally dispose the light source of the second group while improving the brightness by the reflector.

[0041] Furthermore, the first group of light sources are elements that emit light from the side, and the one or more second group of light sources are elements that emit light from the top. This allows light emission to be controlled according to the presence or absence of a reflective wall of the reflector. That is, the first group of light sources emit light toward the reflective wall, and the second group of light sources that are not surrounded by a reflective wall emit light toward the exit side, thereby effectively achieving a light distribution in an approximately normal direction.

[0042] In addition, an optical sheet having a plurality of minute pyramidal prisms with their apexes facing the light source is provided on the output side, whereby the diffusing action of the pyramidal prisms reduces brightness unevenness caused by adding one or more light sources in the second group or by removing the reflective wall of the reflector, thereby improving brightness uniformity.

[0043] Furthermore, a color liquid crystal panel is disposed on the output side, and the first group of light sources emits white or pseudo-white light, and the one or more second group of light sources emits white, pseudo-white, or a predetermined color corresponding to the icon. This allows the color of light required in the telltale section, etc. to be realized by the color development of the color liquid crystal. Furthermore, by making not only the second group of light sources but also the surrounding first group of light sources emit light, the brightness of the telltale section, etc. can be increased. One or more of the light sources in the first and second groups may be a light-emitting source that includes a single red, green, or blue monochromatic LED.

[0044] Furthermore, when illuminating a predetermined area of ​​the substrate, one or more of the second group of light sources arranged in the predetermined area emit light, or the plurality of first group of light sources arranged in the predetermined area and one or more of the second group of light sources arranged in the predetermined area emit light, thereby enabling the display of a telltale section or the like to be performed by the light emitted by the light sources of the second group, and also increasing brightness by adding the light sources of the first group.

[0045] Furthermore, a monochrome liquid crystal panel is disposed on the exit side, and the first group of light sources emits light in white, pseudo-white, or a predetermined color, and the one or more second group of light sources emit light in a color corresponding to the icon displayed in the predetermined area. This allows the light emission color of the second group of light sources to achieve the light emission color required for the telltale section, etc. The one or more light sources of the first and second groups may be a light emission source that includes a single red, green, or blue monochromatic LED.

[0046] The first and / or second light sources are light sources each made up of red, green, and blue monochromatic LEDs, which can be integrated into one light source. This allows the elements of the light source to be unified.

[0047] Furthermore, the surface lighting device according to the embodiment can be applied to warning displays on door mirrors and rearview mirrors, for example, in addition to warning displays on cluster meters, and can also be applied to blind view spot warnings (warning that a vehicle is approaching from behind or to the side).

[0048] Furthermore, the present invention is not limited to the above-described embodiments. Configurations in which the above-described components are appropriately combined are also included in the present invention. Furthermore, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-described embodiments, and various modifications are possible.

[0049] REFERENCE SIGNS LIST 1 Planar lighting device, 1a Light output surface, 2 Bottom frame, 3 Substrate, 4, 5 Light source, 6 Reflector, 6a Frame, 6b Reflection wall, 7 Diffuser, 8 Prism sheet, 9 Polarized reflection film, 10 Top frame, 10a Opening, 20 Liquid crystal panel, 20a Display surface, 20b Telltale section

Claims

1. A substrate, A plurality of first light sources disposed in a first region of the substrate; One or more second light sources arranged in a second region inside the first region at positions different from the first light source; A surface lighting device comprising:

2. The plurality of first light sources are arranged in a lattice pattern in the first region, The one or more second light sources are disposed between the plurality of first light sources disposed in the second region.

2. The spread illuminating device according to claim 1.

3. a reflector having a reflecting wall surrounding each of the first light sources; The plurality of first light sources are arranged in a lattice pattern, The one or more second light sources are disposed at the center of four of the first light sources adjacent vertically and horizontally, At least a portion of the four reflecting walls between the four first light sources in which the second light source is disposed at the center is removed.

3. A spread illuminating device according to claim 1 or 2.

4. the first light sources are elements that emit light from a side surface, The one or more second light sources are elements that emit light from the top surface.

3. A spread illuminating device according to claim 1 or 2.

5. An optical sheet having a plurality of minute pyramid prisms whose apexes face the substrate is provided on the exit side of the substrate.

3. A spread illuminating device according to claim 1 or 2.

6. A color LCD panel is placed on the output side, the first light sources emit white or pseudo-white light; The one or more second light sources emit light in white, pseudo white, or a predetermined color corresponding to an icon.

3. A spread illuminating device according to claim 1 or 2.

7. When illuminating the second region of the substrate, light is emitted from the one or more second light sources arranged in the second region, or light is emitted from the plurality of first light sources arranged in the second region and the one or more second light sources arranged in the second region.

7. The spread illuminating device according to claim 6.

8. A monochrome LCD panel is placed on the exit side, the first light sources emit light in white, pseudo white, or a predetermined color; The one or more second light sources emit light in a color corresponding to an icon displayed in the second area.

3. A spread illuminating device according to claim 1 or 2.

9. The first light source and / or the second light source is a light emitting source in which red, green, and blue monochromatic LEDs are integrated into one.

3. A spread illuminating device according to claim 1 or 2.

10. A substrate; a first group of a plurality of light sources arranged over substantially the entire surface of the substrate; a second group of one or more light sources disposed adjacent to the first group of light sources within a predetermined region of the substrate; a reflector having a reflective wall surrounding each of the first group of the plurality of light sources; Equipped with the first group of light sources is arranged in a lattice pattern over substantially the entire surface of the substrate; The second group of light sources is disposed at the center of the four light sources of the first group that are adjacent vertically and horizontally; At least a portion of the four reflecting walls between the four light sources of the first group in which the light source of the second group is disposed in the center is removed. Surface lighting device.