JP6016190B2 - Light deflection element, illumination switch and surface light source device using the element - Google Patents

Description

  The present invention relates to an optical deflection element, an illumination switch using the element, and a surface light source device. Specifically, the present invention relates to an optical deflecting element for spreading light incident substantially perpendicularly from the incident surface side in the surface direction and emitting the light from the light emitting surface substantially uniformly. The present invention also relates to an illumination switch that is turned on or off by a push button pressing operation, and a surface light source device used as a backlight.

  As an apparatus using a light deflecting element for spreading light incident substantially perpendicularly from the incident surface side in the surface direction and emitting it almost uniformly from the light emitting surface, there are, for example, an illumination switch and a surface light source device. Illumination switches are used in various devices such as communication devices, wireless application devices, electronic measuring instruments, automation devices, office equipment, consumer electronic devices, and operation panels in elevators. The surface light source device is used as a backlight of a liquid crystal display device.

  As an illumination switch, for example, there is a switch whose size is 10 mm in length and width and 10 mm in height when viewed from the front. Recently, the light emitting area as viewed from the front is 19mm in length and breadth and the height is 7.85mm. The lighting switch has a large light emitting area with a large area seen from the front, and is low in height and thin. Is supplied.

  As described above, when the illumination switch has a large area, it is difficult to uniformly illuminate the light emitting area with one LED. Therefore, a large area illumination switch incorporates 6 to 8 LEDs in order to obtain luminance uniformity in the light emitting area. However, in an illumination switch incorporating a large number of LEDs, the price of the illumination switch increases due to the cost of the components. Further, when the illumination switch is thinned, the distance between the surface of the illumination switch and the LED is shortened, so that the luminance is increased in front of each LED, and uneven luminance tends to occur in the light emitting area.

  Similarly, even in the case of a surface light source device, if the area of the light emitting area increases, it becomes difficult to uniformly illuminate the whole with one LED.

  Accordingly, there is a demand for an optical assembly in which a wide light-emitting area can be uniformly illuminated by reducing the light emitted from one or a small number of LEDs, and the thickness can be reduced. In particular, those applicable to illumination switches and surface light source devices are required. As such an optical assembly, those disclosed in Patent Documents 1 and 2 are known.

(Regarding Patent Document 1)
Patent Document 1 discloses an example of an optical assembly. This optical assembly includes a light source, a light guide, and a light diffusing element (light deflecting element). The light guide has a through-hole penetrating vertically, and a light source is disposed in the lower part of the through-hole, and a light diffusing element is housed in the upper part of the through-hole. On the entire upper surface of the light diffusing element, a plurality of prisms are provided radially from the center toward the outer peripheral edge, and concentric concave and convex grooves are formed on the lower surface. In addition, concentric grooves are formed on the upper surface of the light guide, and a plurality of prisms are formed radially on the entire lower surface.

  The light emitted upward from the light source enters the light diffusing element and is totally reflected by the prism on the upper surface of the light diffusing element. The light beam reflected by the prism of the light diffusing element spreads in the outer peripheral direction and enters the light guide. The light that has entered the light guide body spreads in the outer circumferential direction while repeating total reflection in the light guide body, and gradually leaks from the upper surface of the light guide body in the middle to cause the upper surface of the light guide body to shine almost uniformly.

  However, in the optical assembly having such a structure, since most of the light emitted upward from the light source is totally reflected by the prism of the light diffusing element, there is almost no light emitted upward from the upper surface of the light diffusing element. There is a problem that the brightness of the central portion is too low. Further, when the light diffusing element and the light guide are separately formed, the light traveling direction changes abruptly at the boundary between them, so that luminance unevenness occurs at the boundary between the light diffusing element and the light guide. On the other hand, when the light diffusing element and the light guide are molded integrally, the shape becomes complicated, so that the molding is difficult and the cost is high.

(Regarding Patent Document 2)
Patent Document 2 discloses another optical assembly. The optical assembly of Patent Document 2 includes a light source, a reflective layer, and a structured surface element (light deflection element). A plurality of prisms are provided radially on the entire top surface of the structured surface element from the center toward the outer periphery. The light source is disposed in the center of the upper surface of the reflective layer, and the structured surface element is disposed thereon.

  In this optical assembly, the light emitted from the light source is guided from the central part to the outer peripheral part while repeating reflection between the prism of the structured surface element and the reflective layer, and the light leaked from the prism in the middle of the light guide. The light is emitted upward. Therefore, the loss in the reflective layer is large, and the luminance of the optical assembly is likely to decrease.

JP 2006-215509 A (FIGS. 1, 2 and 3) JP-T 2009-521784 (FIG. 1)

  An object of the present invention is to provide an optical deflection element that can cope with an increase in the area of a light emitting area and has high luminance uniformity on the light emitting surface. Furthermore, an object of the present invention is to provide an illumination switch or a surface light source device using the light deflection element.

The light deflection element according to the present invention has a light incident side surface and a light output side surface facing each other, and the light incident side surface is disposed between the light incident side surface and the light output side surface. There is a light guide region for guiding light toward the outer peripheral direction on the outer peripheral side of the light incident region of the surface, and the light emitting region has a light guide region in the region facing the light incident region. multiple deflection pattern for reflecting toward the light incident from the surface of the incident side to the light guide region is formed radially around the optical axis of light incident to the light incident region, the deflection pattern , A pair of slopes inclined in the circumferential direction of a circle centered on the optical axis of the light incident on the light incident area, and the width of the deflection pattern is the optical axis in the area close to the optical axis. Gradually increases from the distance from the front and at the end of the region far from the optical axis And decreased gradually toward the tip of the deflection pattern positioned farther from the optical axis, the deflection pattern is characterized by being arranged at a gap.

In the light deflection element according to the present invention, a pair inclined in the circumferential direction of a circle centering on the optical axis of the light incident on the light incident region , in a region facing the light incident region on the surface on the light emitting side. Since the plurality of deflection patterns formed by the slopes of the light beam are formed radially about the optical axis of the light incident on the light incident area, a part of the light incident from the light incident area is reflected by the deflection pattern. It is sent to the light guide region, spreads in the outer circumferential direction, and is emitted to the outside from the light emitting side surface. Therefore, according to the light deflection element of the present invention, the light emitting area can be widened, and the peripheral portion is not easily darkened even if the light emitting area is widened.

On the other hand, in the light deflection element according to the present invention, since the gap is formed between the deflection patterns , a part of the light incident from the light incident area is emitted to the outside from the gap between the deflection patterns . Therefore, light entering the light input region is nearly fed toward the outer periphery Ru prevents the central portion of the light incident area becomes dark. In addition, the width of the deflection pattern gradually increases as the distance from the optical axis increases in the region near the optical axis, and the deflection pattern positioned on the side far from the optical axis at the end of the region far from the optical axis. Since it gradually decreases toward the tip, the luminance unevenness of the light deflection element can be reduced and light can be emitted uniformly.

In an embodiment of the optical deflection element according to the present invention, both sides of the deflection pattern coincide with a radial direction centered on the optical axis in a region close to the optical axis.

  In another embodiment of the light deflection element according to the present invention, the thickness of the light guide region gradually decreases as the distance from the optical axis increases. Therefore, the light entering the light guide region is emitted to the outside little by little while being guided in the outer peripheral direction while being repeatedly reflected on both surfaces of the light guide region, and uniformly emits the light emitting area of the light deflection element. As a method of emitting light little by little from the light guide region, there is a method of applying diffusion ink to the back surface of the light guide region or forming an optical pattern. According to this embodiment, the manufacturing process of the light deflection element Is not complicated.

  In still another embodiment of the light deflection element according to the present invention, the light incident area is recessed in a spherical shape. According to such an embodiment, it is possible to spread the light that is transmitted through the light incident region and incident on the light deflection element, and it is possible to improve the uniformity of luminance.

  In still another embodiment of the light deflection element according to the present invention, the gap emits light from the surface on the light emission side to the outside, and may be a flat surface, a curved surface, or a bent surface. . Further, the deflection pattern and the gap may be formed smoothly, and the cross section may be sinusoidal as a whole.

  The region facing the light incident region on the light emitting side surface may be a flat surface at least in the center when the slope is leveled, or may be a rotationally symmetric curved surface with the optical axis as the center. Good. The former is easier to manufacture the light deflection element, but the latter can spread the light transmitted through the light incident region.

  In still another embodiment of the light deflection element according to the present invention, the inclined surface is not provided in the vicinity of the optical axis in a region facing the light incident region on the light incident side surface. If the slope is provided up to the position of the optical axis, many slopes gather at the position of the optical axis, making it difficult to manufacture the slope (or the slope portion of the molding die). According to this embodiment, such difficulty can be avoided.

  In still another embodiment of the light deflection element according to the present invention, a light diffusing portion for diffusing light is provided on the incident-side surface in the light guide region. The light diffusing portion can be formed by, for example, an annular concavo-convex pattern centered on the optical axis, a radial pattern, a dot pattern, a wrinkle shape or a fine pattern, or printing of diffusing ink. According to such an embodiment, since the light guided through the light guide region is reflected and diffused by the light diffusing section, the uniformity of the luminance distribution of the light emitted from the light deflection element is improved.

  In still another embodiment of the optical deflection element according to the present invention, the sectional shapes of the deflection patterns are different from each other. According to such an embodiment, ring-shaped luminance unevenness hardly occurs.

  An optical assembly according to the present invention includes the light deflection element according to the present invention, and a light source arranged to face the light incident area of the light deflection element. According to the present invention, it is possible to produce an optical assembly that has a large light emitting area and that can uniformly emit light as a whole.

  The illumination switch according to the present invention includes a push button, the light deflection element according to the present invention disposed behind the push button so as to face the push button, and the light incident area of the light deflection element. And a first contact and a second contact that are electrically connected to each other when the push button is pressed. According to the present invention, it is possible to manufacture an illumination switch that has a large light emitting area and can emit light uniformly.

  In the illumination switch according to the present invention, the distance between the push button and the light source changes between when the push button is pressed and when the push button is not pressed. The luminance distributions of the light emitting areas at the time of light source emission when the button is not pressed are different from each other. In this case, since the brightness changes between when the push button is pressed and when the push button is not pressed, the visual operation feeling of the illumination switch is improved.

  A surface light source device according to the present invention includes a light deflection element according to the present invention, a light source disposed to face the light incident area of the light deflection element, and a diffusion disposed on a light emission side of the light deflection element. And a seat. According to the present invention, it is possible to manufacture a surface light source device having a large light emitting area and capable of uniformly emitting light as a whole.

  The liquid crystal display device according to the present invention includes the surface light source device according to the present invention and a liquid crystal panel disposed on the light emitting side of the surface light source device. According to such a liquid crystal display device, the visibility of the screen of the liquid crystal display device is improved.

  The means for solving the above-described problems in the present invention has a feature of appropriately combining the constituent elements described above, and the present invention enables many variations by combining such constituent elements. .

FIG. 1 is a perspective view of an illumination switch according to Embodiment 1 of the present invention. FIG. 2 is an exploded perspective view of the illumination switch shown in FIG. FIG. 3 is a cross-sectional view showing a cross section taken along line XX of FIG. FIG. 4 is a perspective view of a switch board in which a terminal spring is insert-molded in the illuminated switch according to the first embodiment of the present invention. FIG. 5A is a perspective view of a light control plate (light deflection element) used in the illumination switch according to the first embodiment of the present invention. FIG. 5B is a top view of the light control plate. 6A is a partially broken perspective view of the light control plate of FIG. 5A. FIG. 6B is a cross-sectional view of the light control plate. FIG. 7A is an enlarged view of a Y portion in FIG. 5B. FIG. 7B is an enlarged view of a portion Z in FIG. 7A. FIG. 8A is a perspective view of a deflection pattern. FIG. 8B is a top view of the deflection pattern. FIG. 8C is a cross-sectional view along the length direction of the deflection pattern. FIG. 8D is an enlarged cross-sectional view along the width direction of the deflection pattern. FIG. 9 is a diagram for explaining the behavior of light emitted from the light source. 10A and 10B are a cross-sectional view along the length direction and a cross-sectional view along the width direction showing the behavior of the light transmitted through the light transmission part between the deflection patterns. FIG. 11 is a graph showing the luminance distribution of the comparative example having no light control plate and the luminance distribution of the first embodiment including the light control plate. FIG. 12A is a diagram illustrating a luminance distribution of a comparative example having no light control plate. FIG. 12B is a diagram illustrating a luminance distribution of Embodiment 1 including a light control plate. FIG. 13 is a graph showing the luminance distribution in the light emitting area of the illumination switch when the push button is pressed and not pressed. FIG. 14A is a diagram showing a luminance distribution in the light emitting area of the illumination switch in a state where the push button is pressed. FIG. 14B is a diagram illustrating a luminance distribution in the light emitting area of the illumination switch when the push button is not pressed. 15A, 15B, and 15C are diagrams showing various cross-sectional shapes of the deflection pattern. 16A, 16B, and 16C are diagrams showing various cross-sectional shapes of the deflection pattern and the light transmission portion. 17A, 17B, and 17C are diagrams showing various cross-sectional shapes of the light transmission portion between the deflection patterns. 18A, 18B, and 18C are diagrams showing various cross-sectional shapes of the deflection pattern and the light transmission portion. FIG. 19 is a graph showing the minimum inclination angle at which light is totally reflected on the upper surface of the light control plate when light in a direction parallel to the central axis is incident on the inclined upper surface of the light control plate. FIG. 20 is a cross-sectional view illustrating a modification of the light control plate according to the first embodiment of the present invention. FIG. 21A is a schematic diagram illustrating another shape of the light incident region of the light control plate according to the first embodiment of the present invention. FIG. 21B is a schematic diagram illustrating still another shape of the light incident region of the light control plate according to the first embodiment of the present invention. 22A and 22B are an enlarged plan view and a plan view showing an enlarged pattern region of the light control plate according to the second embodiment of the present invention. 23A and 23B are an enlarged plan view and a plan view showing an enlarged pattern region of the light control plate according to Embodiment 3 of the present invention. 24A and 24B are a perspective view and a plan view of a dot-shaped deflection pattern provided on the light control plate according to the third embodiment of the present invention. FIG. 25A is a perspective view seen from the lower surface side of the light control plate according to the fourth embodiment of the present invention. FIG. 25B is an enlarged cross-sectional view of the light control plate of FIG. 25A. 26A, 26B, and 26C are diagrams showing different cross-sectional shapes of the deflection pattern. FIG. 27A is a schematic diagram for explaining the cause of ring-shaped luminance unevenness. FIG. 27B is a cross-sectional view showing deflection patterns having different inclination angles. FIG. 27C is a schematic diagram for explaining how light from the light source spreads when the deflection pattern of FIG. 27B is used. FIG. 28 is a schematic sectional view showing a liquid crystal display device according to Embodiment 5 of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments, and various design changes can be made without departing from the gist of the present invention.

(Embodiment 1)
[Structure of illuminated switch]
Hereinafter, the structure of the illumination switch according to the first embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3 are a perspective view, an exploded perspective view, and a cross-sectional view taken along line XX of FIG. 1, of the illumination switch 11 according to the first embodiment of the present invention. FIG. 4 is a perspective view of the switch board 12 used in the illumination switch 11. FIG. 5A is a perspective view of the light deflection element used in the illumination switch 11, that is, the light control plate 31 as viewed from the back side. FIG. 5B is a top view of the light control plate 31. 6A and 6B are a perspective view and a cross-sectional view, partly broken, of the light control plate 31. FIG. 1 and 2 show the illumination switch 11 in an upright state, but in the following, the vertical direction refers to the vertical direction in the cross-sectional view of FIG. 3 regardless of FIG. 1 and FIG. (For example, the direction from the light source 25, the first contact 22a, the second contact 22b, and the like toward the light guide region 37 and the push button 14 is referred to as an upward direction).

  Referring to FIG. 1, the illumination switch 11 has an appearance of a switch board 12, external terminals 13 a, 13 b, 21 a, 21 b exposed on both side surfaces of the switch board 12, and a push button 14 disposed on the upper surface of the switch board 12. And a frame 15 having a frame shape surrounding the periphery of the push button 14. Although the illumination switch 11 may have a round shape when viewed from the front, a rectangular shape as shown in FIG. 1 will be described below.

  In the illumination switch 11, when the push button 14 is pushed in, the internal contacts are brought into conduction and the illumination switch 11 is turned on. When the push button 14 is released, the push button 14 returns to the original position, the internal contacts are insulated and the illumination switch 11 is turned off.

  The illumination switch 11 is composed of components as shown in FIG. The switch substrate 12 is formed of a white resin (for example, white polycarbonate resin). The switch substrate 12 has a box-shaped storage portion 16 on the upper surface thereof. A plurality of claws 17 for attaching the frame 15 are provided on both opposite sides of the switch board 12. A circular recess 24 is formed on the bottom surface of the storage portion 16.

  The switch board 12 is insert-molded by embedding four terminal springs 18a, 18b, 19a, 19b. The light source terminal springs 18a and 18b are respectively provided with light source mounting electrode pads 20a and 20b at one end and external terminals 21a and 21b at the other end. In the state where the terminal springs 18a and 18b are insert-molded on the switch board 12, as shown in FIG. 4, the two electrode pads 20a and 20b are exposed side by side in the center of the recess 24, and the external terminals 21a and 21b are switched. It protrudes from the side surface of the substrate 12.

  The terminal springs 19a and 19b have external terminals 13a and 13b at both ends, respectively. The terminal spring 19a includes a first contact 22a having a rectangular shape at the center. The terminal spring 19b includes a second contact 22b having a rectangular shape at the center. In a state where the terminal springs 19a and 19b are insert-molded on the switch substrate 12, as shown in FIG. 4, the first contact 22a is exposed in the vicinity of the electrode pads 20a and 20b. The second contact 22b is exposed at the edge in the recess 24 on the opposite side of the first contact 22a. The external terminals 13 a and 13 b of the terminal springs 19 a and 19 b protrude from the side surface of the switch board 12.

  The light source 25 is an LED, and is mounted on the center of the switch substrate 12 by bonding the electrodes on the lower surface to the electrode pads 20a and 20b as shown in FIG. As the light source 25, a white LED is often used, but a colored LED such as a red LED or a blue LED may be used.

  As shown in FIG. 2, the reversing spring 26 has a shape in which the outer peripheral portion of the disc spring is cut out at a plurality of locations. The reversal spring 26 is fitted inside the recess 24 (see FIG. 3). The outer peripheral edge of the reversing spring 26 overlaps with the second contact 22b and is in contact with the second contact 22b. The inner peripheral portion of the reversing spring 26 is located above the first contact 22a and is separated from the first contact 22a.

  The light source 25 is disposed at a position corresponding to the light incident area 32 of the light control plate 31, and the light control plate 31 and the light source 25 constitute an optical assembly. Further, the upper surface of the light source 25 protrudes from the hole 27 provided at the center of the reversing spring 26.

  The light control plate 31 is placed on the reversing spring 26 (see FIG. 3). The light control plate 31 is formed of a transparent resin having a large refractive index, such as polycarbonate resin (PC) or polymethyl methacrylate resin (PMMA). Moreover, you may produce the light-control board 31 with transparent glass etc. other than resin. Thick ribs 39 are provided on the outer periphery of the upper surface of the light control plate 31, and support portions 40 project from the central portions of the sides of the ribs 39. The joint 40a is recessed. Other detailed shapes of the light control plate 31 will be described later.

  A diffusion sheet 41 is disposed on the light control plate 31. The diffusion sheet 41 has a high haze value, and preferably has a haze value of 90% or more, for example. At the center of the four sides of the diffusion sheet 41, a fitting portion 42 protrudes. The diffusion sheet 41 is supported on the light control plate 31 such that the fitting portion 42 is fitted into the fitted portion 40 a of the light control plate 31.

  The push button 14 is formed of a translucent resin and has a function of scattering light. For example, it is molded from POM (polyoxymethylene), milky white PC (polycarbonate resin), or milky white PMMA (polymethyl methacrylate). Further, the push button 14 may be colored red or green, and may be printed or stamped with characters or marks.

  The frame 15 is formed in a frame shape with an opaque resin. The push button 14 is slidably fitted into the window 46 of the frame 15, and flanges 45 provided at four corners of the push button 14 come into contact with the lower surface of the edge of the window 46, thereby pushing the push button 14. This prevents the window 46 from passing upward. Note that the support portion 40 of the light control plate 31 is also provided with a step portion 40 b for making contact with the lower surface of the edge of the window 46. Engagement hooks 47 protrude downward on both side surfaces of the frame 15, and the frame 15 can be detachably attached to the switch board 12 by hooking the engagement hooks 47 on the claws 17 of the switch board 12.

  The illumination switch 11 is assembled as shown in FIG. That is, the switch board 12 is insert-molded with terminal springs 18a, 18b, 19a and 19b. The light source 25 is mounted on the electrode pads 20a and 20b on the upper surface of the switch substrate 12, and is electrically connected between the electrode pads 20a and 20b. When the reversing spring 26 is placed on the upper surface of the switch board 12, the reversing spring 26 is fitted and positioned inside the recess 24, and the upper surface (light emitting surface) of the light source 25 is projected upward from the hole 27 of the reversing spring 26. The lower end of the outer periphery of the reversing spring 26 is brought into contact with the second contact 22b. The light control plate 31 having the diffusion sheet 41 attached on the upper surface is disposed on the light source 25 and the reversing spring 26. The push button 14 is passed through the window 46 of the frame 15 from the lower surface side. In this state, the push button 14 is overlaid on the light control plate 31 and the diffusion sheet 41, and the frame 15 is overlaid on the switch board 12. Further, the illumination switch 11 is assembled by engaging the engagement hook 47 of the frame 15 with the claw 17 of the switch board 12. In this assembled state, the central axis C of the light control plate 31 substantially coincides with the optical axis of the light source 25 (the axis line that coincides with the principal ray emitted from the light source 25).

[Contact open / close operation]
The illumination switch 11 is opened and closed between the first contact 22a and the second contact 22b as follows. As shown in FIG. 3, when the push button 14 is not pressed, the reversing spring 26 is separated from the first contact 22a and is not in contact with the first contact 22a. And the second contact 22b are open.

  When the push button 14 is pushed downward with a finger, the light control plate 31 is pushed down together with the push button 14. Therefore, the reversing spring 26 is crushed by the operating portion 33 to come into contact with the first contact 22 a, and the first contact 22 a and the second contact 22 b are closed via the reversing spring 26. Since the reversing spring 26 is buckled and deformed when being crushed, a click feeling when the push button 14 is pressed can be obtained.

  When the push button 14 is released, the push button 14 and the light control plate 31 are returned to their original positions by the elastic restoring force of the reversing spring 26, and the reversing spring 26 is separated from the first contact 22a and the first contact 22a. The space between the second contacts 22b is opened. A click feeling can also be obtained by the reversal spring 26 when releasing the push button 14.

[Structure of light control plate]
Next, the shape of the light control plate 31 will be described in detail. 5A is a perspective view seen from the back side of the light control plate 31, and FIG. 5B is an enlarged view showing the light incident region 32 of the light control plate 31. FIG. 6A is a partially broken perspective view of the light control plate 31. FIG. 6B is a cross-sectional view of the light control plate 31.

  The lower surface 51 of the light control plate 31 is a gently inclined surface that falls downward toward the center. The overall shape of the lower surface of the light control plate 31 is a rotationally symmetric frustoconical shape about the central axis C of the light control plate 31 (which coincides with the optical axis of the light source 25). A light incident region 32 that is recessed in a spherical shape is provided at the center of the lower surface of the light control plate 31 (the portion facing the light source 25). On the lower surface of the light control plate 31, an operation portion 33 for pressing the reversing spring 26 protrudes in an annular shape around the light incident region 32. The light incident area 32 has a shape obtained by rotating a recess having the shape shown in FIG. 6B around the central axis C of the light control plate 31.

  A region surrounded by the ribs 39 on the upper surface of the light control plate 31 is a light emitting surface 28 (also referred to as a light emitting area) for emitting light. In this embodiment, the light emitting surface 28 is a flat surface. In the light emitting surface 28, a region facing the light incident region 32 is a pattern region in which a large number of V-groove-shaped deflection patterns 52 are radially arranged.

  8A to 8D show the shape of one deflection pattern 52. FIG. FIG. 8A is a perspective view of the deflection pattern 52. FIG. 8B shows a shape viewed from directly above the deflection pattern 52. 8C and 8D show a cross section along the longitudinal direction of the deflection pattern 52 and an enlarged cross section along the width direction. As shown in FIG. 8D, the deflection pattern 52 is formed by a V-groove composed of two inclined surfaces 53a and 53b (the inclined surface may be a flat surface or a curved surface), as shown in FIG. 8C. The depth of the V-groove gradually changes along the length direction. The deflection pattern 52 has a leaf shape as shown in FIG. 8B when viewed from above. In the center region, the deflection pattern 52 has a V-groove width and depth that gradually increase as the distance from the end on the center axis C side increases. In the outer peripheral region, the V groove increases as the distance from the end on the center axis C side increases. The width and depth of the are decreasing relatively rapidly. The inclination angle β of the inclined surfaces 53a and 53b is about 45 °.

  7A and 7B are enlarged views of the deflection pattern 52 arranged in a radial pattern. FIG. 7A is an enlarged view of a Y portion in FIG. 5B. FIG. 7B is an enlarged view of a Z portion in FIG. 7A. Each of the deflection patterns 52 has an end on the center side on the center axis C of the light control plate 31 and is arranged radially with a point on the center axis C as a center. In a region near the central axis C of each deflection pattern 52, both side edges also coincide with the radial direction centered on a point on the central axis C. The deflection patterns 52 are not arranged without gaps, but flat light transmission portions 54 are formed in the gaps between the deflection patterns 52 as shown in FIG. 7B. The light transmitting portions 54 are also arranged radially with a point on the central axis C as a center. In FIG. 7B, in order to make the light transmission part 54 easy to understand, hatching is applied to one inclined surface 53a and the other inclined surface 53b.

  A region on the outer peripheral side of the light incident region 32 and the pattern region of the light control plate 31 is a light guide region 37 that becomes thinner toward the outer peripheral side.

  When the light control plate 31 is rectangular, if the light guide region 37 is extended to the four corners of the light control plate 31, the thickness of the light guide region 37 is reduced at the corners of the light control plate 31, and the strength is reduced. Or in order to prevent a strength fall, it is necessary to enlarge the thickness of the light control board 31. FIG. Therefore, in the case of the rectangular light control plate 31, the light guide region 37 extends to the center of each side, and the corners are formed to have a constant thickness. Therefore, even if the thickness of the light control plate 31 is thin, it is possible to prevent the strength at the corners from decreasing.

  Furthermore, the strength of the light control plate 31 is increased by providing a thick rib 39 on the outer periphery of the light control plate 31.

[Light switch on and off]
In the illumination switch 11, the light source 25 and the terminal springs 18a and 18b are circuits independent of the switch portion including the first and second contacts 22a and 22b, the reversing spring 26, and the like. Light is emitted by flowing current from 21a and 21b. In order to associate the light source 25 of the illumination switch 11 with the switch portion, the external terminals 13a, 13b, 21a, and 21b of the illumination switch 11 are connected to a control circuit.

  In a general method of use (control method), when the push button 14 is pressed, the control circuit detects that the contact 22a, 22b is closed, the control circuit emits the light source 25, and the illumination switch 11 is turned on. . And the lighting state of the illumination switch 11 continues after the push button 14 returns. When the push button 14 is pressed in the lighting state, the control circuit detects that the contact 22a, 22b is closed, the light source 25 is stopped by the control circuit, and the illumination switch 11 is turned off. Then, even after the push button 14 is restored, the illumination switch 11 remains off.

[Behavior of light during light emission]
Next, the behavior of light when the light source 25 emits light will be described. Consider a case where the push button 14 is not pressed but the light source 25 emits light and the illumination switch 11 is lit.

  First, consider the light L1 emitted from the light source 25 and incident on the light incident region 32 and incident on the deflection pattern 52 formed in the pattern region on the upper surface. The light L1 passes through the light incident region 32 and then enters the deflection pattern 52. The light L1 incident on the deflection pattern 52 is reflected back by the slopes 53a and 53b of the deflection pattern 52 and returns to the lower surface side of the light control plate 31 and enters the light guide region 37 as shown by solid lines in FIGS. 10A and 10B. Proceed toward. The light L1 that has entered the light guide region 37 travels in the outer peripheral direction of the light control plate 31 while repeating total reflection on the upper and lower surfaces of the light guide region 37. Since the incident angle of light decreases every time the light is totally reflected on the upper and lower surfaces of the light guide region 37, the light is emitted from the upper surface or the lower surface of the light guide region 37 to the outside when the incident angle is smaller than the critical angle of total reflection. To do. The light that has been retroreflected by the deflection pattern 52 in this way is sent to the light guide region 37 and is uniformly emitted from the entire light exit surface 28.

  On the other hand, light L2 emitted from the light source 25 and transmitted through the light incident region 32 and incident on the upper light transmitting portion 54 passes through the light transmitting portion 54 as it is, as indicated by a broken line in FIGS. 10A and 10B. The light exits from the center of the light exit surface 28 to the outside.

  Thus, the lights L1 and L2 emitted from the light emitting surface 28 are diffused by the diffusion sheet 41 and the push button 14, and the push button 14 is caused to emit light uniformly.

  In the illumination switch 11 according to the first embodiment of the present invention, the light emitted from the light source 25 can be recursively reflected by the deflection pattern 52 and carried in the outer peripheral direction, so that the light emitted from one light source 25 can be spread over a wide area. Can be spread. Therefore, a large light emitting area (for example, an area having a width of 20 mm or more in the vertical and horizontal directions) can be emitted by a small number of light sources 25. Further, even if the height (thickness) of the illumination switch 11 is reduced (for example, 7.4 mm or less), a wide light emitting area can be emitted.

  However, when there is no gap between the deflection patterns 52 in the pattern area as in the prior art, most of the light emitted to the central portion is sent to the outer peripheral portion, and the luminance of the central portion of the light control plate 31 is increased. Decreases and darkens. On the other hand, in the illumination switch 11 of the first embodiment, since the light transmission part 54 is provided between the deflection patterns 52, the light L2 transmitted through the light transmission part 54 is emitted from the upper surface of the light control plate 31 immediately after that. Thus, the central portion of the light control plate 31 can be prevented from becoming dark. In addition, by adjusting the area ratio between the deflection pattern 52 and the light transmitting portion 54, the luminance of the central portion and the outer peripheral portion of the light control plate 31 can be adjusted, and luminance unevenness can be reduced.

  Therefore, according to Embodiment 1 of the present invention, a thin illumination switch having a large light emitting area can be manufactured at low cost, and the entire light emitting area can be made to emit light with a uniform luminance distribution. Become. Further, since the light is diffused by the diffusion sheet 41 or the push button 14 provided on the upper surface of the illumination switch 11, no matter which direction the light is emitted from the light control plate 31, it will shine when viewed from the front. You can make it visible.

  FIG. 11 is a graph showing the luminance distribution of the comparative example having no light control plate and the luminance distribution of the first embodiment including the light control plate (by computer simulation). In FIG. 11, a thick solid line (“no light control plate”) indicates the luminance distribution in the light emitting area of the illumination switch of the comparative example that does not have the light control plate (that is, the illumination switch configured by the light source, the diffusion sheet, and the push button). It is a represented graph. In FIG. 11, a thin solid line (“Example 1”) is a graph showing the luminance distribution in the light emitting area of the illumination switch according to the first embodiment of the present invention, and further, a one-dot chain line (“direct light”) and a broken line ( The “light guide light”) represents the brightness distribution of the first embodiment separately for the brightness distribution of the directly emitted light and the brightness distribution of the light guide light. Each luminance distribution represents a luminance distribution on a diagonal line of the light emitting area when the light emitting area is 20 mm in length and width. The horizontal axis in FIG. 11 represents the distance measured diagonally from the center of the light source 25 (central axis C), and the vertical axis represents the luminance (arbitrary unit).

  FIG. 12A is a diagram showing the luminance distribution in the light emitting area of the comparative example in black and white. FIG. 12B is a diagram showing the luminance distribution in the light emitting area of Embodiment 1 in black and white. In any case, the brightness of the light emitting area is higher in the region with higher brightness (whiter region), and the luminance of the light emitting area is lower in the region with lower lightness (blackish region).

  When the light control plate is not used, the light emitted from the light source is only diffused by a diffusion sheet or a push button, so that the graph of “no light control plate” in FIG. 11 and the luminance distribution diagram of FIG. In addition, the luminance of the central portion of the light emitting area is high and only the central portion is brightly shining. A broken line graph (“light guide light”) in FIG. 11 is light emitted from the upper surface of the light control plate 31 after passing through the deflection pattern 52 and being totally reflected at least once on the upper or lower surface of the light control plate 31. Represents the luminance distribution. If only the deflection pattern 52 is provided in this way, the light at the center is bent in the circumferential direction by the deflection pattern 52 and totally reflected by the upper surface of the light control plate 31 and sent in the outer circumferential direction. As described above, the luminance distribution is almost flat, but the luminance is lowered at the center. On the other hand, the one-dot chain line (“direct light”) graph in FIG. 11 is transmitted through the light transmitting portion 54 and transmitted through the light control plate 31 without being reflected by the upper and lower surfaces of the light control plate 31. The luminance distribution of the light emitted from the upper surface of the control plate 31 is shown. As described above, the luminance distribution due to the direct light transmitted through the light transmitting portion 54 has a high luminance at the center of the light emitting area, as indicated by the one-dot chain line in FIG. Therefore, the luminance distribution in the case where the deflection pattern 52 and the light transmission portion 54 are provided in a radial pattern is the sum of the broken line graph and the one-dot chain line graph in FIG. 11, and emits light as shown in the thin solid line in FIG. 11 and FIG. 12B. The luminance distribution of the area is almost uniform.

[Comparison of luminance distribution when pushing the push button and returning]
Next, in the illumination switch 11 according to the first embodiment of the present invention, the results obtained by simulation of the luminance distribution of each light emitting area in the state where the push button 14 is pressed and the state where the push button 14 is not pressed (return state) are obtained. explain. FIG. 13 is a graph showing a luminance distribution on a line segment passing through the center of the light emitting area and parallel to any side in the illumination switch 11 having a light emitting area of 20 mm in length and width. The solid line graph indicates the luminance distribution when the push button 14 is not pressed, and the broken line graph indicates the luminance distribution when the push button 14 is pressed. The horizontal axis in FIG. 13 represents the distance measured from the center of the light source (center axis C), and the vertical axis represents the luminance (arbitrary unit).

  FIG. 14A shows the luminance distribution of the light emitting area (vertical and horizontal 20 mm each) when the push button 14 is pressed. FIG. 14B shows the luminance distribution of the light emitting area when the push button 14 is not pressed. 14A and 14B also indicate that the brightness of the light emitting area is higher in a region with higher lightness (whiter region), and the luminance of the light emitting area is lower in a region with lower lightness (blackish region).

  When the push button 14 is not pressed, the entire light emitting area emits light with substantially uniform luminance as shown in the solid line graph of FIG. 13 and FIG. 14B. On the other hand, when the push button 14 is being pressed, the light control plate 31 is close to the light source 25, so that the center of the light emitting area becomes slightly brighter as shown in the broken line graph of FIG. 13 and FIG. The part becomes a little dark.

  In the illumination switch 11 according to the first embodiment of the present invention, since the light emission condition of the light emission area when the push button 14 is pressed changes from the light emission condition when the push button 14 is not pressed, the push button 14 is pressed. It becomes easy to understand that it is in a state. Therefore, when the push button 14 is pressed, a feeling of clicking is obtained by the reversing spring 26, and the light emission state of the push button 14 is changed, so that the feeling of operation of the push button 14 is improved both tactilely and visually.

[Various shapes of deflection pattern and direct light generation surface]
Next, various shapes (modifications) of the deflection pattern 52 and the light transmission portion 54 will be described. In the pattern region, as shown in FIG. 15A, the deflection pattern 52 is formed by the V grooves 53 a and 53 b formed with flat slopes, and a flat light transmission portion 54 is formed between the deflection patterns 52. However, the shapes of the deflection pattern 52 and the light transmission part 54 are not limited to this, and various cross-sectional shapes are possible. For example, in the pattern region shown in FIG. 15B, the valley portion of the deflection pattern 52 is formed flat and the flat surface is used as the light transmission portion 54. Further, in the pattern region shown in FIG. 15C, flat light transmission portions 54 are formed between the deflection patterns 52, and valley portions of the deflection patterns 52 are formed flat, and the flat surfaces serve as the light transmission portions 54. In the case where the light control plate 31 is molded using a mold, if the shape is as shown in FIG. 15A, the shape of the portion of the mold that forms the light transmitting portion 54 is determined by the shape of the tip of the tool, so that variation is reduced. 15B, the degree of freedom of the ratio of the light transmission portion 54 is increased (this effect is obtained when the deflection pattern 52 or the light transmission portion 54 is formed by directly processing the light control plate 31). Is the opposite.) If the shape is as shown in FIG. 15C, the light transmission part 54 is dispersed, so that the light transmission part 54 does not shine and become noticeable when viewed through the push button 14.

  FIG. 16A shows a case where the light transmission portion 54 is flat and the inclined surfaces 53a and 53b of the deflection pattern 52 are curved so as to swell into the groove. FIG. 16B shows a case where the light transmission part 54 is flat and the slopes 53a and 53b of the deflection pattern 52 are curved so as to be retracted from the groove. If the slopes 53a and 53b are curved as shown in FIGS. 16A and 16B, the light spreads when reflected by the slopes 53a and 53b due to the lens effect, so that the light is reflected by the upper surface of the light control plate 31. The light spreads after being converted into the light, and the light is easily emitted uniformly from the upper surface of the light control plate 31. 17A, 17B, and 17C are cases where the slopes 53a and 53b are flat surfaces and the light transmitting portion 54 is curved. In each of the shapes of FIGS. 17A to 17C, the light transmitting portion 54 is curved and the light transmitted through the light transmitting portion 54 spreads, so that the light transmitting portion 54 is less noticeable when viewed through the push button 14. FIG. 16C shows a case where both the slopes 53a and 53b and the light transmission part 54 are curved, and the cross section is, for example, sinusoidal. 18A to 18C show a case where the deflection pattern 52 and the light transmission part 54 are bent and the deflection pattern 52 and the light transmission part 54 have a polygonal cross section.

  When the light transmission part 54 is curved, it may be curved in the direction opposite to that shown in FIGS. 17A and 17B. Further, the sectional shape of the deflection pattern 52 may be similar along the length direction, but may be gradually deformed. For example, it may have a V-groove shape as shown in FIG. 10B at the center, and gradually approach a sine wave as shown in FIG.

  15A-15C, FIG. 16A-16B, FIG. 17A-17C, and FIG. 18A-18B, it is intuitive that which region is the deflection pattern 52 and which region is the light transmitting portion 54. It is obvious. However, when both the deflection pattern 52 and the light transmitting portion 54 are curved as shown in FIG. 16C, or when there is a surface with an inclination angle that is difficult to judge as shown in FIG. At 52, it is not clear from where the light transmission portion 54 is. However, since the behavior of the light incident from the lower surface of the light control plate 31 varies depending on the direction of the light beam, the boundary between the deflection pattern 52 and the light transmission portion 54 does not necessarily have to be clear, and may be ambiguous. In the present embodiment, it is sufficient that the pattern region includes a region that refracts the transmitted light source light in the circumferential direction and a region that transmits light from the light source almost linearly when viewed from above. There is no problem even if the direction of the transmitted light gradually changes in the meantime. However, as an indication of distinction, it can be explained as follows.

  Now, the upper surface (light emitting surface 28) of the light control plate 31 having a refractive index n is tilted at a certain inclination angle α, and light parallel to the optical axis (center axis C) of the light source 25 is applied to the upper surface of the light control plate 31. Let us consider the case where the light is incident on. When the inclination angle α of the upper surface of the light control plate 31 is large, the light is totally reflected on the upper surface of the light control plate 31, and when the inclination angle α of the upper surface of the light control plate 31 is small, the light is reflected on the upper surface of the light control plate 31. To Penetrate. Therefore, the inclination angle β of the inclined surfaces 53 a and 53 b of the deflection pattern 52 is larger than the inclination angle of the light transmitting portion 54. The curve in FIG. 19 indicates that when light parallel to the optical axis of the light source 25 is incident toward the upper surface (light emitting surface 28) of the light control plate 31 having a refractive index n, all of the light is incident on the upper surface of the light control plate 31. It represents the minimum tilt angle α that is reflected. That is, in the region above the curve in FIG. 19, the light incident on the upper surface of the light control plate 31 is totally reflected, and in the region below the curve in FIG. To Penetrate. Therefore, even when the deflection pattern 52 and the light transmission part 54 change smoothly, the value on the curve (the inclination angle α corresponding to the refractive index n of the light control plate 31) is used as a boundary. A region with a large inclination angle is the deflection pattern 52, and a region with a smaller inclination angle can be considered as the light transmission part 54.

  In the patterns shown in FIGS. 6A, 6B, 7A, and 7B, the deflection pattern 52 and the light transmitting portion 54 are formed radially around a point on the central axis C. The ratio of the area of the light transmission portion 54 to the area of the deflection pattern 52 (projected area viewed from above) in the ring-shaped region centered on the point is constant near the center axis C and far from the center axis C. However, it is getting bigger gradually. However, the ratio of the area of the light transmission part 54 to the area of the deflection pattern 52 in the ring-shaped region can be adjusted as appropriate within a range of 0 to 100%. For example, the light control plate 31 is redesigned so that the ratio of the light transmission part 54 is increased at a low luminance at the central portion of the upper surface, and the ratio of the light transmission part 54 is reduced at a high luminance. do it. For example, in the above embodiment, the amount of light emitted from the upper surface of the light control plate 31 through the light transmission part 54 in the pattern region is about 25% of the amount of light emitted from the entire upper surface of the light control plate 31. ing.

  In the above embodiment, the light emitting surface 28 is a flat surface. However, as shown in FIG. 20, the entire light emitting surface 28 is curved, and the deflection pattern 52 is formed on the curved surface. Also good. In the example shown in FIG. 20, the light exit surface 28 is recessed at the center thereof, and is inclined smoothly when it exceeds the curved portion at the highest position inclined in an inverted conical shape around the light exit surface 28. When the entire light exit surface 28 is curved in this way, the light emitted from the light exit surface 28 spreads due to the lens effect, so that the light directly emitted from the light exit surface 28 and the total reflection are repeated several times. Light emitted from the emission surface 28 is likely to be mixed, and the boundary between both lights becomes inconspicuous.

  In the above embodiment, the light incident area 32 of the light control plate 31 is curved in a spherical shape. However, the light incident area 32 may be a flat surface as shown in FIG. 21A. If the light incident region 32 is flat, the light control plate 31 can be easily manufactured. On the other hand, the light transmitted through the light incident region 32 is difficult to spread. In this case, it is preferable to increase the density of the deflection pattern 52.

  Further, as shown in FIG. 21B, a Fresnel lens-shaped light incident region 32 having an optical effect equivalent to that of the spherical light incident region 32 may be used. If the light incident area 32 of the light control plate 31 is formed into a Fresnel lens shape, the thickness of the light control plate 31 can be reduced. However, when the Fresnel lens shape is used, the light passing through the stepped portion gathers in the center, and there is a risk that the uniformity of luminance may be lowered. Therefore, it is preferable to increase the density of the deflection pattern 52.

(Embodiment 2)
22A and 22B are a plan view showing a part of the light control plate according to Embodiment 2 of the present invention, that is, a pattern region in an enlarged manner, and an enlarged sectional view thereof. In the light control plate of the second embodiment, a spherical convex portion 56 is formed at the center of the upper surface of the light control plate 31, and a large number of deflection patterns 52 are arranged radially around the convex portion 56. The deflection pattern 52 has a shape as shown in FIG. 8, and the end on the center side of the deflection pattern 52 is located at the edge of the convex portion 56. Since the other structure of the light control plate is the same as that of the first embodiment, the description thereof is omitted (the same applies to the following embodiments).

  In the structure as in the first embodiment, it is difficult to process the slopes 53a and 53b radially at the center of the light emitting surface 28, and therefore the slopes 53a and 53b may not be formed at the center. When the slopes 53a and 53b cannot be formed, the amount of light that passes straight upward through the light control plate increases, and the luminance uniformity decreases. In such a case, processing of the inclined surfaces 53a and 53b can be facilitated by starting the deflection pattern 52 from a location deviating from the center of the light emitting surface 28 as in the second embodiment. Further, by providing a rotationally symmetric convex portion 56 at the center of the light emitting surface 28, the light near the center is diffused so that the light does not pass straight through the center to prevent uneven brightness.

(Embodiment 3)
23A and 23B are a plan view showing a part of a light control plate according to Embodiment 3 of the present invention, that is, a pattern region in an enlarged manner, and an enlarged sectional view thereof. In the light control plate of the second embodiment, a large number of deflection patterns 52 in the form of dot patterns are distributed discretely in the pattern region provided on the upper surface of the light control plate 31. 24A and 24B are a perspective view and a plan view of a deflection pattern 52 in the form of a dot pattern. The deflection pattern 52 is formed in a diamond shape by four inclined surfaces, and is arranged radially about the center of the light incident region 32. The inclination angle ε of the inclined surfaces 53a and 53b of the deflection pattern 52 is 45 °, and the angle τ of the angle located in the radial direction when the deflection pattern 52 is viewed from above is 30 °. In FIG. 23A, the deflection patterns 52 are arranged with a certain degree of regularity, but may be arranged at random. In this embodiment, the entire portion of the pattern area provided on the light emitting surface 28 where the deflection pattern 52 is not provided is the light transmitting portion 54. If the deflection patterns 52 are arranged radially, it can be said that such light transmission parts 54 are also formed radially.

  Even in the deflection pattern 52 as shown in FIGS. 24A and 24B, the light incident on the inclined surface can be recursively reflected. Therefore, even when such a light control plate is used, the same light control plate as in the first embodiment is used. An effect can be produced. In the first embodiment, since the deflection pattern 52 extending long is formed, the streak of light transmitted through the deflection pattern 52 is easily visible through the push button 14, but in the second embodiment, the dot-shaped deflection pattern 52 is dispersed. Therefore, the light pattern transmitted through the deflection pattern 52 is less noticeable.

(Embodiment 4)
FIG. 25A is a perspective view from the back side showing the light control plate 61 according to Embodiment 4 of the present invention. FIG. 25B is a cross-sectional view of the light control plate 61. On the lower surface 51 of the light control plate 61, light diffusion portions, that is, a large number of ring-shaped uneven patterns 62 are formed concentrically. When the uneven pattern 62 is formed on the lower surface of the light control plate 61 as described above, the light reflected by the lower surface 51 is diffused, so that the uniformity of luminance in the light emitting area is improved.

  In order to make the luminance uniform, a textured shape, a fine pattern, a radial pattern, or the like may be provided in addition to the uneven pattern 62. At this time, the brightness can be made even more uniform by adjusting the density and shape of the fine pattern.

  Further, the deflection pattern 52 may be constituted by only one inclined surface 53a as shown in FIGS. 26A and 26B. In that case, only the slope 53a of one direction may be used like FIG. 26A, and the slopes 53a and 53b from which an inclination direction differs may be arrange | positioned alternately like FIG. 26B. Further, even when the deflection pattern 52 includes two inclined surfaces 53a and 53b, the cross section of the deflection pattern 52 may be asymmetric as shown in FIG. 26C.

  If the cross-sectional shape of the deflection pattern 52 is the same for any of the deflection patterns 52, the light emitted at an angle from the optical axis of the light source 25 spreads in a rotationally symmetrical manner. That is, f1 in FIG. 27A represents a ripple of light incident on the light incident region 32, f2 represents a ripple of light reflected on the light exit surface 28, f3 represents a ripple of light reflected on the light guide region 37, f4 represents a ripple of light emitted from the light control plate 31, and f5 represents a ripple of light emitted from the upper surface of the push button 14. Therefore, the light emitted from the light source 25 in the vicinity of the optical axis spreads in the order of the ripples f 1 → f 2 → f 3 → f 4 → f 5, and a light ripple such as f 5 is generated on the surface of the push button 14. Therefore, a ripple f5 shown in FIG. 27A appears in the light emitting area of the illumination switch 11, and ring-shaped luminance unevenness is likely to occur.

  In order to avoid this, as shown in FIG. 27B, the cross-sectional shape (or inclination angle of the inclined surface) of the deflection pattern 52 may be sequentially changed. If the cross-sectional shape of the deflection pattern 52 is varied, the light ripples are distorted and spread accordingly. That is, f1-f5 in FIG. 27C is a case where the deflection pattern 52 as shown in FIG. 27B is used, f1 represents a ripple of light incident on the light incident region 32, and f2 represents light reflected on the light exit surface 28. F3 represents a ripple of light reflected from the light guide region 37, f4 represents a ripple of light emitted from the light control plate 31, and f5 represents a ripple of light emitted from the upper surface of the push button 14. Also in this case, the light emitted from the light source 25 to the vicinity of the optical axis spreads in the order of the ripples f1 → f2 → f3 → f4 → f5, and a distorted ripple such as f5 is formed on the surface of the push button 14. Arise. In addition, the shape of the ripples such as f5 differs depending on the direction of the light emitted from the light source 25. Therefore, the unevenness of luminance becomes inconspicuous and the appearance is improved by overlapping the ripples of the light emitted in each direction.

(Embodiment 5)
FIG. 28 is a schematic sectional view showing a liquid crystal display device 71 according to Embodiment 5 of the present invention. In this liquid crystal display device 71, a surface light source device 73 serving as a backlight is disposed on the back surface of a liquid crystal panel 72. In the surface light source device 73, the diffusion sheet 75 is disposed on the upper surface of the light control plate 74 according to the present invention (for example, the light control plate of the first embodiment), the light source 25 is placed facing the light incident region 32, and light control is performed. A reflection sheet 76 is arranged to face the lower surface of the plate 74.

  The light control plate 74 has the same structure as the light control plate described so far, but has a larger light emitting area than that for the illumination switch.

  In each of the above embodiments, a concave deflection pattern is shown, but the deflection pattern may be formed in a convex shape.

DESCRIPTION OF SYMBOLS 11 Illumination switch 12 Switch board 14 Push button 15 Frame 16 Storage part 25 Light source 26 Reversing spring 28 Light emission surface 31 Light control board 32 Light incident area 37 Light guide area 41 Diffusion sheet 52 Deflection pattern 53a, 53b Slope 54 Light transmission part 61 Light control plate 62 Uneven pattern 71 Liquid crystal display device

Claims (16)

It has a light incident side surface and a light emission side surface facing each other,
Between the light incident side surface and the light emission side surface, a light guide region for guiding light toward the outer peripheral direction is provided on the outer peripheral side of the light incident region of the light incident side surface. Have
The light incident region facing the region of the surface of the light emission side, the multiple deflection pattern for reflecting toward the light incident from the surface of the light incident side to the light guide region, the light incident Formed radially around the optical axis of the light incident on the region,
The deflection pattern is configured by a pair of slopes inclined in the circumferential direction of a circle centered on the optical axis of light incident on the light incident region, and the width of the deflection pattern is a region close to the optical axis. Then, it gradually increases with increasing distance from the optical axis, and at the end of the region far from the optical axis, gradually decreases toward the tip of the deflection pattern located on the side far from the optical axis,
The optical deflection element, wherein the deflection patterns are arranged with a gap. 2. The optical deflection element according to claim 1 , wherein both sides of the deflection pattern coincide with a radial direction centered on the optical axis in a region close to the optical axis .   The light deflection element according to claim 1, wherein the light guide region gradually decreases in thickness as the distance from the optical axis increases.   The light deflection element according to claim 1, wherein the light incident area is recessed in a spherical shape.   The optical deflection element according to claim 1, wherein the gap is a flat surface, a curved surface, or a bent surface.   The optical deflection element according to claim 1, wherein the deflection pattern and the gap have a sine wave cross section as a whole.   The light deflection element according to claim 1, wherein a region facing the light incident region on the light emitting side surface is a flat surface when the deflection pattern is leveled.   The region facing the light incident region on the light emitting side surface is a rotationally symmetric curved surface with the optical axis as a center when the deflection pattern is leveled. Optical deflection element.   2. The light deflection element according to claim 1, wherein the deflection pattern is not provided in the vicinity of the optical axis in a region facing the light incident region on the light emitting side surface.   The light deflection element according to claim 1, wherein a light diffusing portion for diffusing light is provided on the incident-side surface in the light guide region.   The optical deflection element according to claim 1, wherein the deflection patterns have different cross-sectional shapes. The light deflection element according to any one of claims 1 to 11 ,
A light source disposed to face the light incident area of the light deflection element;
An optical assembly comprising: A push button,
The light deflection element according to any one of claims 1 to 11 , which is disposed behind the push button so as to face the push button.
A light source disposed to face the light incident area of the light deflection element;
A first contact and a second contact that are electrically connected to each other when the push button is pressed;
Illuminated switch with. The illumination switch according to claim 13 , wherein the luminance distribution of the light emitting area when the light source emits light when the push button is pressed is different from the luminance distribution of the light emitting area when the light source emits light when the push button is not pressed. . The light deflection element according to any one of claims 1 to 11 ,
A light source disposed to face the light incident area of the light deflection element;
A diffusion sheet disposed on the light exit side of the light deflection element;
A surface light source device. A surface light source device according to claim 15 ;
A liquid crystal panel disposed on the light emitting side of the surface light source device;
A liquid crystal display device.