JP5853739B2 - Collimated light source and surface light source device - Google Patents

Description

  The present invention relates to a collimated light source and a surface light source device, and more particularly to a collimated light source for allowing parallel light to enter a light guide plate of the surface light source device and a surface light source device using the collimated light source.

  Some surface light source devices used for displays such as amusement devices can change the light source to be turned on so that only a part of the light emitting surface can be illuminated. In such a surface light source device, a plurality of light sources are arranged in a line along the end surface of the light guide plate. When only a part of the light source is lit, the light emitted from the lit light source is introduced into the light guide plate as parallel light. In such a surface light source device, the parallel light incident on the light guide plate is guided almost straight to the front of the light source, so that only the front of any light source can emit light, and various effects by light are possible. become. In addition, since light is guided straight to the front of each light source, the light is emitted to the front of other light sources, making it difficult to shine ahead of the other light sources, and the boundary between the shining area and the non-shining area It can be made clear. Furthermore, each light source includes LED chips of red light, green light, and blue light, and the light guide plate can emit light in various colors by switching the LED chip to be lit.

(A surface light source device of Patent Document 1)
An example of such a type of surface light source device is disclosed in Patent Document 1. FIG. 1 is a perspective view of a surface light source device 11 described in Patent Document 1. FIG. The surface light source device 11 includes a collimated light source 12 and a light guide plate 13.

  The collimating light source 12 includes a plurality of light sources 14 incorporating LED chips for red light, green light, and blue light, and a collimating lens array 15. The collimating lens array 15 is formed by arranging a plurality of collimating lenses 16 side by side, and is formed into a plate having a uniform thickness with a transparent resin.

  One collimating lens 16 and one light source 14 in the collimating lens array 15 are shown in FIG. The rear end surface of the collimating lens 16 is a light incident surface 17, and a diffusion pattern region 18 is formed at the center of the light incident surface 17. Side portions extending forward from both ends of the light incident surface 17 are each composed of a reflection wall 19 and a step surface 20. The reflection wall 19 is a flat surface spreading outward as it goes forward, and the step surface 20 is a flat surface parallel to the light incident surface 17. Further, the front surface of the collimating lens 16 is constituted by an emission side lens 21 (convex lens) having an arc shape when viewed from the thickness direction.

  The light guide plate 13 is formed into a flat plate shape with a transparent resin having a high refractive index, and a light emission pattern 23 (for emitting light from the front surface 13b (light emission surface) by totally reflecting light to an appropriate portion of the back surface 13a. 4) is formed.

  In the surface light source device 11, as shown in FIG. 1, the collimating lens array 15 is positioned by bringing the front end face of each collimating lens 16 into contact with the light incident end face 13 c of the light guide plate 13. The collimating lens 16 is disposed so as to be opposed to the light incident surface 17.

  In the surface light source device 11, light incident on the collimator lens 16 from both ends (flat regions) of the light incident surface 17 out of the light emitted from the light source 14 is refracted by the light incident surface 17 and directed forward. move on. Further, the light incident on the collimating lens 16 from the diffusion pattern region 18 is diffused in the diffusion pattern region 18 and spreads left and right, and the light diffused toward both side surfaces of the collimating lens 16 is totally reflected by the reflection wall 19. To be directed forward. The light emitted from the collimator lens 16 is collimated by the emission side lens 21 and is emitted from the emission side lens 21 as substantially parallel light. Accordingly, the amount of light distributed is reduced in the central portion of the collimating lens 16 because light is diffused by the diffusion pattern region 18, and the light diffused in the diffusion pattern region 18 is distributed on both sides of the collimating lens 16. For this reason, the amount of light increases, and the intensity of the parallel light emitted from the collimating lens 16 is substantially uniform over the entire width of the collimating lens 16. The light that has entered the light guide plate 13 from the collimator lens array 15 is guided through the light guide plate 13 and is reflected from the light output pattern 23 to be output from the surface 13 b of the light guide plate 13, thereby forming the light output pattern 23. The illuminated area emits light.

(Derivative form from the surface light source device of Patent Document 1)
In the surface light source device 11 as described above, there is a possibility that a positional deviation occurs between the collimating lens array 15 and the light guide plate 13 due to vibration or the like after the surface light source device 11 is incorporated into a device. In order to prevent this, as shown in FIGS. 3 and 4, the collimating lens array 15 and the light guide plate 13 are integrated, and the front end face of each collimating lens 16 is formed continuously with the light incident end face 13 c of the light guide plate 13. is there. In this case, a substantially triangular through hole 22 is formed between the exit side lenses 21 of the adjacent collimator lenses 16 for the exit side lens 21 of the collimator lens 16.

JP 2011-233416 A

  Even in the above surface light source device, when a higher quality device is required, radial luminance unevenness and striped color unevenness as shown in FIG. 5 become a problem. The radial luminance unevenness referred to here is one in which the luminance in the left-right oblique direction increases immediately before each collimating lens 16 (the end of the light guide plate 13). The cause of such radial luminance unevenness is considered as follows.

  When the collimating lens array 15 and the light guide plate 13 are integrated by injection molding as shown in FIG. 3, the width between the front end surface of the collimating lens 16 and the light guide plate 13 needs to be about 3 mm for the convenience of injection molding. And As the light beam L1 shown in FIG. 3, the exit side lens 21 is partially lost at this connected portion, and thus the light beam passing through the connected portion is not refracted by the exit side lens 21. Therefore, the light beam L1 is emitted in an oblique direction without being converted into parallel light, and the straight front of the light source 14 becomes dark at the end of the light guide plate 13, and a bright line due to the light beam L1 is generated in the forward oblique direction as shown in FIG. Further, even in the surface light source device of Patent Document 1 in which the collimator lens 16 and the light guide plate 13 are not integrated, if the front end surface of the collimator lens 16 is in close contact with the light incident end surface 13c of the light guide plate 13, for the same reason. The light beam that passes through the closely contacted portion is not converted into parallel light by the emission side lens 21, and the front side becomes darker and a bright line is generated in the diagonally forward direction.

  Further, the striped color unevenness means that even if the LED chip of red light, green light, and blue light is turned on and the light source 14 emits white light, the vicinity of the light incident end face 13c of the light guide plate 13 (from the light incident end face 13c). In the region of about 10-40 mm), a striped pattern slightly colored in red (R), green (G), and blue (B) can be seen. Such color unevenness is particularly noticeable in the immediate vicinity of the light incident end face of the light guide plate. The cause of the striped color unevenness is considered as follows.

  When LED chips of red light, green light, and blue light are arranged in the light source in the width direction, when viewed from the direction (thickness direction) perpendicular to the light emitting surface of the light guide plate, the parallel light of each color in the light guide plate The angle shifts, and the shift between the colors increases at a position away from the light incident end face. Therefore, as shown in FIG. 4, in the light source 14, the green light LED chip 24 </ b> G, the red light LED chip 24 </ b> R, and the blue light 24 </ b> B are arranged in a line along the thickness direction of the light guide plate 13. On the other hand, when the collimating lens array 15 is integrated with the light guide plate 13 or is brought into close contact with the light incident end surface 13c of the light guide plate 13, a relatively large penetration is made between the exit side lenses 21 of the adjacent collimating lenses 16. A hole 22 is created. The through hole 22 has a substantially triangular shape when viewed from the thickness direction, and the maximum length D in the front-rear direction is about 4 mm.

  Therefore, the light passing through the emission side lens 21 like the light beam L2 shown in FIG. 3 is collimated and enters the light guide plate 13, but a part of the light enters the light guide plate 13 as shown in FIG. It leaks upward through the through hole 22 without being incident. The light leaking in this way is shifted by the green light (G) of the LED chip 24G, the red light (R) of the LED chip 24R, and the blue light (B) of the LED chip 24B as shown in FIG. Color irregularities such as 5 appear.

  The present invention has been made in view of such technical problems, and an object of the present invention is to reduce the occurrence of uneven brightness and color unevenness in a collimated light source or a surface light source device using a collimated light source. There is.

Collimated light source according to the present invention is a collimated light source having a plurality of light sources, a plurality of collimating lenses for emitting collimated the light emitted from said light source, said collimator lens, respectively, wherein A light incident surface for introducing light from a light source, a light exit surface located on the opposite side of the light incident surface, and extending from both sides of the light incident surface toward the light exit surface, from the light incident surface A light reflecting wall for reflecting the introduced light, a through hole formed in the thickness direction of the collimator lens formed between the light incident surface and the light exit surface, and the through hole introduced from the light incident surface A light refracting surface formed on the edge of the through hole for collimating light passing through the hole , and the plurality of collimating lenses are arranged side by side in the width direction, and the adjacent collimating lenses are arranged side by side. Part of And characterized in that it.

In the collimated light source according to the present invention, the light that has been introduced into the collimating lens from the light incident surface and spread laterally is reflected by the light reflecting wall and emitted forward from the light emitting surface. Further, the light introduced into the collimating lens substantially forward from the light incident surface is converted into parallel light by passing through the through-hole, and is emitted forward from the light exit surface. Moreover, in this collimated light source, a through hole for collimating the light passing therethrough is formed between the light incident surface and the light exit surface, so that the output surface of the collimated light source is on the light incident surface of the light guide plate. Even if it is in close contact or formed integrally with the light guide plate, the light refracting surface at the edge of the through hole for parallelizing the light beam does not disappear, and uneven brightness is present at the end of the light guide plate. It becomes difficult to occur. In addition, by arranging the through hole between the light incident surface and the light exit surface, the length of the through hole in the direction perpendicular to the light incident surface can be shortened, so that light is less likely to leak from the through hole and the luminance is increased. Unevenness is also reduced. Further, in the collimating light source according to the present invention, the collimating lenses are arranged side by side in the width direction, and the adjacent collimating lenses are part of the side surfaces of each other, so that a plurality of collimating lenses are integrated. Handling becomes easy.

  In an embodiment of the collimated light source according to the present invention, a distance between a light refracting surface closer to the light incident surface and a light refracting surface farther from the light incident surface of the edge of the through hole is equal to the through hole. The center portion of the through hole is smaller than both end portions of the through hole. In such an embodiment, when viewed from the thickness direction of the collimating lens, the shape of the through hole is substantially concave and optically functions as a convex lens, so that the light passing therethrough can be collimated. In addition, since the length of the through hole in the direction perpendicular to the light incident surface is reduced at the central portion of the through hole, light leakage at the central portion of the through hole is reduced.

  In another embodiment of the collimated light source according to the present invention, the light refracting surface on the side close to the light incident surface of the edge of the through hole is configured by a curved surface, a curved surface in an arc shape, or a plurality of planes. It is characterized by that. According to such an embodiment, light can be refracted by the light refracting surface formed on the surface of the through-hole that is closer to the light incident surface, so that the light refraction on the side closer to the light incident surface of the through-hole. By making the surface into an appropriately shaped surface, for example, a surface that swells so that the central portion projects into the through hole, light can be collimated.

  Further, in this embodiment, the light refracting surface on the side far from the light incident surface of the edge of the through hole is constituted by a plane parallel to the light output surface and an inclined surface inclined with respect to the light output surface. It is desirable that According to such a configuration, light can be refracted and collimated even on a light refracting surface far from the light incident surface, so that the shape of the light refracting surface closer to the light incident surface can be simplified. Can do. In particular, the central portion of the light refracting surface on the side far from the light incident surface in the edge of the through hole is a plane parallel to the light exit surface, and the light on the side far from the light incident surface in the edge of the through hole. It is desirable that both sides of the refracting surface are inclined surfaces that are inclined such that an end close to the central portion is close to the light incident surface and an end far from the central portion is far from the light incident surface.

  Yet another embodiment of the collimated light source according to the present invention is characterized in that the light reflecting wall is constituted by a curved surface or a plurality of planes bulging toward the outside of the collimating lens. According to such an embodiment, the light reflecting wall can be formed substantially in a parabolic mirror shape or a concave mirror shape, so that the light reflected forward can be converted into parallel light.

  Still another embodiment of the collimated light source according to the present invention is characterized in that the light incident surface has a region where a diffusion pattern is provided and a flat region where no diffusion pattern is provided. According to such an embodiment, the light incident on the region provided with the diffusion pattern is diffused by the diffusion pattern, and the light incident on the flat surface passes through the light incident surface without being diffused. By adjusting, the distribution of light entering the collimating lens from the light source can be optimized. For example, the diffusion pattern may be provided with a groove or a ridge extending in the thickness direction of the collimating lens.

A first surface light source device according to the present invention includes a light guide plate and the collimated light source according to the present invention disposed along a light incident end surface of the light guide plate, and a light output surface of the collimated light source is the light guide plate. It is characterized in that it is joined or integrally formed with the light incident end face. According to such a surface light source device, since a plurality of collimating lenses are integrated, handling at the time of assembling the surface light source device becomes easy. Further, luminance unevenness and color unevenness generated at the end of the light guide plate can be reduced.

A second surface light source device according to the present invention is formed integrally with a plurality of light sources, a light guide plate, and an end of the light guide plate, and converts the light emitted from the light source into parallel light to guide the light. A surface light source device having a plurality of collimating lenses to be incident on an optical plate, wherein a member in which the plurality of collimating lenses and the light guide plate are integrated includes a light incident surface for introducing light from the light source, and a front surface A light reflecting wall that extends from both sides of the light entry surface toward the light guide plate and reflects light introduced from the light incident surface; a through-hole penetrating in the thickness direction of the collimator lens; A light refracting surface formed at the edge of the through hole for collimating the light introduced from the writing light surface and passing through the through hole , and the plurality of collimating lenses are arranged in the width direction. Adjacent collimating lenses And a part are continuous. In such a surface light source device, since the plurality of collimating lenses and the light guide plate are integrated, there is no displacement between the collimating lens and the light guide plate, and the labor for attaching the collimating lens to the light guide plate can be saved. Further, luminance unevenness and color unevenness generated at the end of the light guide plate can be reduced. Furthermore, in the surface light source device according to the present invention, the collimating lenses are arranged side by side in the width direction, and adjacent collimating lenses are part of the side surfaces of each other, so that a plurality of collimating lenses are integrated, The handling becomes easy.

In an embodiment of the second surface light source device according to the present invention, when viewed from the side, the end of the light reflecting wall on the side far from the light incident surface is located on the side far from the light incident surface of the through hole. It is characterized by being located farther from the light incident surface than the end. According to such an embodiment, light that does not pass through the through hole can be more reliably reflected forward by the light reflecting wall.

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

FIG. 1 is a perspective view of the surface light source device disclosed in Patent Document 1. FIG. FIG. 2 is a perspective view showing one collimating lens and one light source in the collimating lens array shown in FIG. FIG. 3 is a plan view showing the surface light source device of FIG. 1 in which a collimating lens array and a light guide plate are integrated. FIG. 4 is a schematic cross-sectional view taken along the line PP in FIG. FIG. 5 is an explanatory diagram schematically showing the luminance unevenness and the color unevenness generated in the surface light source device of FIG. FIG. 6 is a plan view of the collimated light source according to the first embodiment of the present invention. 7 is a cross-sectional view taken along the line QQ in FIG. FIG. 8 is a perspective view showing a collimating lens array used in the collimating light source of FIG. FIG. 9 is an enlarged plan view showing one collimating lens in the collimating lens array. FIG. 10A is a perspective view showing the structure of the light incident surface of the collimator lens. FIG. 10B is a perspective view showing a different structure of the light incident surface of the collimator lens. FIG. 11A shows the collimating light source of Embodiment 1 in which the collimating lens array has a wedge shape. FIG. 11B shows a collimated light source according to a comparative example. FIG. 12A is a ray diagram illustrating a state in which light emitted from the light source is collimated by the light reflection wall and the through hole. FIG. 12B is a ray diagram illustrating a state in which light emitted from the light source is converted into parallel light by the through hole. FIG. 13A is a diagram illustrating light reaching the light exit surface without being affected by the light reflecting wall or the through hole. FIG. 13B is a diagram illustrating an improved example in which light reaching the light exit surface is eliminated without being affected by the light reflecting wall or the through hole. FIG. 14 is a diagram simulating the locus of light emitted from the light source in the collimated light source of the first embodiment. FIG. 15 is a perspective view showing the surface light source device according to Embodiment 1 of the present invention. FIG. 16 is a plan view of the surface light source device according to the first embodiment. FIG. 17 is a diagram illustrating a result of measuring directivity characteristics at the end portion of the light guide plate in front of the light source that is turned on in the conventional example and the surface light source device of the first embodiment. FIG. 18 is a diagram illustrating a result of measuring the directivity characteristics at the end portion of the light guide plate in front of the middle of the light sources that are turned on in the conventional light source device and the surface light source device of the first embodiment. . FIG. 19A is a diagram illustrating a luminance distribution during light emission at the end portion of the light guide plate in a conventional surface light source device. FIG. 19B is a diagram illustrating a luminance distribution during light emission at the end portion of the light guide plate in the surface light source device according to the first embodiment of the present invention. FIG. 20 is a diagram showing a change in luminance along the Y-axis direction at a position of 10 mm from the light incident end face based on FIGS. 19A and 19B. FIG. 21A is a plan view showing a collimated light source according to Embodiment 2 of the present invention. FIG. 21B is a cross-sectional view of the collimated light source. FIG. 22 is a plan view of a surface light source device 72 according to Embodiment 2 of the present invention. FIG. 23 is a plan view showing a surface light source device 81 according to Embodiment 3 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)
Hereinafter, a collimated light source and a surface light source device according to Embodiment 1 of the present invention will be described with reference to FIGS.

  FIG. 6 is a plan view showing the collimated light source 31 according to Embodiment 1 of the present invention, and the collimated light source 31 includes a collimating lens array 32 and a light source 33. FIG. 7 is an enlarged view showing a cross section taken along line QQ in FIG. 6. FIG. 8 is a perspective view of the collimating lens array 32. FIG. 9 is an enlarged plan view showing one collimating lens 34 in the collimating lens array 32. FIG. 10A is a perspective view showing the structure of the light incident surface 35 of the collimating lens 34, and FIG. 10B is a perspective view showing a different structure of the light incident surface 35 of the collimating lens 34.

  As shown in FIG. 6, the collimated light source 31 includes a collimating lens array 32 and a plurality of light sources 33. The collimating lens array 32 is formed by integrally forming a plurality of collimating lenses 34 having the same shape in a horizontal row. In FIG. 6, four collimating lenses 34 are integrated, but the collimating lens array 32 may have a large number of collimating lenses 34 integrated according to the width of the light guide plate. The collimating lens array 32 is manufactured by injection molding using a transparent resin having a large refractive index such as polycarbonate resin (PC), acrylic resin (PMMA), polystyrene resin (PS), or the like as a raw material. The collimating lens array 32 can also be manufactured by cutting.

  As shown in FIG. 8, the collimating lens array 32 includes a light incident surface 35 for disposing the light source 33 on the end surface of each collimating lens 34, and light is incident on the end surface opposite to the light incident surface 35. A light exit surface 36 parallel to the surface 35 is provided. The light exit surface 36 is a flat surface continuous from end to end of the collimating lens array 32. Further, in the collimating lens array 32, the thickness (height) h of the light exit surface 36 is equal to the thickness of the light incident end surface of the light guide plate described later, and the thickness H of the light incident surface 35 is greater than the thickness h of the light exit surface 36. Is also getting bigger. Therefore, as shown in FIG. 7, the collimating lens array 32 has a wedge-shaped cross section in the front-rear direction (cross section parallel to the XZ plane described later), and both the front and back surfaces 40b and 40a are inclined surfaces. Yes. In the following, the X-axis direction is defined in the direction perpendicular to the light exit surface 36, the Y-axis direction is defined in the width direction of the collimator lens array 32 orthogonal to the X-axis direction, and orthogonal to the X-axis direction and the Y-axis direction. The Z-axis direction is defined in the thickness direction of the collimating lens array 32.

  As shown in FIGS. 8 and 9, a diffusion pattern region 37 is formed at the center of the light incident surface 35, and a flat surface region 45 without a pattern is formed on both sides of the diffusion pattern region 37. Referring to FIG. 10A, both left and right end portions of the light incident surface 35 are smooth flat surface regions 45, and a diffusion pattern region 37 is formed between the left and right flat surface regions 45. The diffusion pattern region 37 is a region where a V-groove diffusion pattern 47 extending in the thickness direction of the collimating lens array 32 is formed. The diffusion pattern region 37 is further divided into two regions. The central portion of the diffusion pattern region 37 is a region 46a where the density of the diffusion pattern 47 is small. Here, the diffusion pattern 47 and the strip-shaped planes 48 are arranged alternately and regularly. Between the region 46a and the flat surface region 45 is a region 46b where the density of the diffusion pattern 47 is high, and the diffusion pattern 47 is arranged without a gap.

  Note that the diffusion pattern region 37 is formed from a convex shape such as a prism shape or a semi-cylindrical shape extending in the thickness direction of the collimating lens array 32 as shown in FIG. 10B instead of the V-groove diffusion pattern 47 of FIG. 10A. A diffusion pattern 49 may be provided.

  As shown in FIG. 9, both side surfaces of each collimating lens 34 are formed by light reflecting walls 38 extending from both ends of the light incident surface 35 toward the light exit surface 36. The continuous portions 41 provided at the front end portion of the reflecting wall 38 are continuous and integrated with each other. The ends of adjacent light reflecting walls 38 are smoothly connected by a curved surface. The light reflecting wall 38 bulges outward in the width direction of the collimating lens 34. For example, the light reflecting wall 38 may be a curved surface formed by a curved surface such as an arc or a parabola when viewed from the Z-axis direction, and is configured by a plurality of planes and bent into a polygonal line when viewed from the Z-axis direction. It may be. Further, the distance between the left and right light reflecting walls 38 (the distance in the direction parallel to the light exit surface 36) becomes wider toward the light exit surface 36.

  The thickness direction (Z-axis direction) of each collimator lens 34 is located between the light incident surface 35 and the light exit surface 36, particularly at a location closer to the light entrance surface 35 than the center of the light entrance surface 35 and the light exit surface 36 in the X-axis direction. A through hole 39 having a substantially concave shape penetrating into the hole is opened. The edge of the through hole 39 on the side close to the light incident surface 35 is a substantially arc-shaped first light refracting surface 42 that swells so that the central portion projects into the through hole 39. The first light refraction surface 42 may be curved so as to have an arc shape when viewed from the Z-axis direction, or may be bent into a polygonal line by a plurality of planes. Further, the edge of the through hole 39 on the side close to the light exit surface 36 is also a second light refracting surface 43 that protrudes so that the central portion projects into the through hole 39. The second light refracting surface 43 is a flat surface 43a whose central portion is perpendicular to the X-axis direction. It has become. Thus, the length of the through hole 39 in the X-axis direction is the shortest at the center of the through hole 39. The shortest length D of the through hole 39 needs to be as short as possible in order to minimize light leakage from the through hole 39. Assuming mass production by injection molding, the shortest length D of the through hole 39 is required to be about 1 mm in consideration of the durability of the mold.

  Both side surfaces 44 of the through hole 39 are inclined planes so as to be substantially parallel to the light reflecting wall 38. The distance between the side surface 44 of the through hole 39 and the light reflecting wall 38 is required to be at least about 1.5 mm when mass production of the collimating lens array 32 is assumed by injection molding.

  Furthermore, the corner portion between the first light refraction surface 42 and the side surface 44 and the corner portion between the inclined surface 43b and the side surface 44 are appropriately curved with a curvature. This is because when the collimating lens array 32 is injection-molded, a radius of about 0.2 mm is required at a location corresponding to the corner portion of the through hole 39 in consideration of the durability of the injection mold. When the lens array 32 is molded, the corner portion of the through hole 39 becomes a curved surface.

  As shown in FIG. 7, a light emitting color green LED chip 51G, a red LED chip 51R, and a blue LED chip 51B are mounted in the light source 33. Each LED chip 51G, 51R, 51B is a transparent resin. 52 is sealed. These LED chips 51G, 51R, 51B are arranged along the Z-axis direction. Further, the transparent resin 52 is covered with a coating portion 53 made of a white resin on the outer peripheral surface except the front surface, and a portion where the transparent resin 52 on the front surface is exposed serves as an emission window 54 for emitting light. Thus, the light source 33 emits white light from the emission window 54 by simultaneously lighting the LED chips 51G, 51R, and 51B, and colors one or two LED chips to emit light. Emit light. The light source 33 is disposed so as to face the light incident surface 35 of the collimator lens 34. The height of the exit window 54 of the light source 33 is smaller than the height of the light incident surface 35 of the collimating lens 34.

Here, the dimension example of the collimating lens 34 which comprises the collimating lens array 32 is described (refer FIG. 9). However, this dimension is an example and is not limited to these dimensions.
Arrangement pitch of collimating lens 34: 10.8 mm
Collimating lens 34 width W: 10.8 mm
Collimating lens 34 length S: 9 mm
The width of the exit window 54 of the light source 33: 2.5 mm
Width w of light incident surface 35: 4.4 mm
Width M of region 46a having a small diffusion pattern density: 2.2 mm
Diffusion pattern density (area density) in region 46a: 50%
Vertical angle of diffusion pattern 47: 80 degrees Radius of curvature of light reflecting wall 38: about 27 mm
Center length D of through-hole 39: about 1 mm Curvature radius of first light refracting surface 42: about 2.3 mm
Inclination θ of the inclined surface 43b in the second light refracting surface 43: about 21 degrees

  Next, the effects of the collimated light source 31 of the first embodiment having the above-described structure will be described with reference to FIGS. 11A shows the collimated light source 31 of the first embodiment in which the collimating lens array 32 has a wedge shape, and FIG. 11B shows a comparative example with the collimated light source 31 of the first embodiment.

  In the comparative example shown in FIG. 11B, the collimating lens array 32 has a uniform thickness. When the thickness of the collimating lens array 32 is uniform as in this comparative example, when the thickness of the light guide plate is reduced, the thickness of the collimating lens array 32 is also reduced. Therefore, the thickness of the light incident surface 35 of the collimating lens array 32 is thinner than the height of the light emission window of the light source 33, and a part of the light emitted from the light source 33 enters the light incident surface 35 as shown in FIG. 11B. The light use efficiency decreases. Further, when the LED chips 51G, 51R, and 51B having different emission colors are arranged in the thickness direction, even if the light source 33 attempts to emit white light, some light (for example, part of green or blue light) ) Does not enter the light incident surface 35, the color balance of the light incident on the light incident surface 35 is lost, and the light emitted from the collimating lens array 32 is colored.

  On the other hand, in the case of the collimated light source 31 of the first embodiment, the collimating lens array 32 has a wedge shape. Therefore, even if the thickness of the light guide plate is reduced, the thickness of the light incident surface 35 is set to the emission window of the light source 33. It can be larger than the height. Therefore, as shown in FIG. 11A, leakage of light emitted from the light source 33 is reduced, and light utilization efficiency is improved. Further, even if the LED chips 51G, 51R, 51B having different emission colors are arranged in the thickness direction, the light of any emission color is difficult to leak from the light incident surface 35, so the color of the light incident on the collimating lens array 32 It is possible to prevent the outgoing light from being colored due to a loss of balance.

  Further, since the light incident surface 35 has a structure as shown in FIG. 10A, the light incident from the light incident surface 35 is spread in the width direction by the diffusion pattern region 37. That is, the light emitted from the light source 33 has a high luminance in front of the light source 33 and a low luminance in the left-right oblique direction. However, since the light emitted forward from the light source 33 is scattered by the diffusion pattern 47, the light incident on the central portion of the light incident surface 35 is also sent to the end of the collimating lens 34. On the other hand, the light emitted from the light source 33 in the diagonal direction enters the collimating lens 34 from the flat surface region 45 at the side end of the light incident surface 35. As a result, the intensity distribution in the width direction of the light incident on the collimating lens 34 is made uniform.

  The arrangement of the diffusion pattern 47 may be appropriately designed so that the intensity distribution of the light that has passed through the light incident surface 35 is substantially uniform in the Y-axis direction. In the first embodiment, the central region 46 a of the diffusion pattern region 37 has a lower diffusion pattern density than the regions 46 b at both ends of the diffusion pattern region 37, and the intensity of light emitted from the collimating lens 34 is the central portion ( The light source 33 is prevented from becoming too small (in front of the light source 33).

  As shown in FIG. 11A, the light beam L3 incident on the collimating lens 34 is guided while being totally reflected by the back surface 40a and the front surface 40b of the collimating lens 34, and is emitted from the light output surface 36. Since the first light refracting surface 42 acts as a convex lens, the light ray L3a incident on the central portion of the first light refracting surface 42 out of the light ray L3 passes through the through-hole 39 as shown in FIG. 12A. The light is refracted by one light refracting surface 42 to be collimated. Then, the light beam L3a is transmitted through the flat surface 43a of the second light refraction surface 43 as it is, and is collimated in the X-axis direction from the light output surface 36.

  Further, as shown in FIG. 12B, the light beam L3b incident on the end portion of the first light refracting surface 42 is refracted by the first light refracting surface 42 to be collimated when passing through the through hole 39. However, although the light beam collimated by the first light refracting surface 42 is inclined from the X-axis direction, it is bent in a direction parallel to the X-axis direction by being refracted by the inclined surface 43b of the second light refracting surface 43. The collimated light beam L3b is emitted from the light exit surface 36.

  Further, the light beam L3c guided in the direction away from the through hole 39 is incident on the light reflecting wall 38 as shown in FIG. 12A, is totally reflected by the light reflecting wall 38 and is converted into parallel light, and from the light exit surface 36. A collimated light beam L3c is emitted. In this way, most of the light emitted from almost the entire light exit surface 36 is converted into parallel light.

  In addition, since both side surfaces 44 of the through hole 39 are inclined substantially parallel to the light reflection wall 38, it is difficult to block light traveling toward the light reflection wall 38. Further, as the inclination at the end of the arc-shaped first light refracting surface 42 approaches the direction orthogonal to the light exiting surface, the ratio of the light incident on the end of the first light refracting surface 42 being totally reflected and becoming lossy light increases. Therefore, the shape of the end of the first light refracting surface 42 has a gentle inclination so that there is no total reflection loss.

  In the collimating lens 34 having such a structure, depending on the positional relationship between the light reflecting wall 38 and the through hole 39, as shown in FIG. An outgoing light beam L4 may be generated. For example, in the case of the collimating lens 34 having the above dimension example, light emitted in a direction forming an angle of 20 to 32 degrees with respect to the X-axis direction is emitted without hitting the through hole 39 or the light reflecting wall 38. The light is emitted from the surface 36. Since such light cannot control the emission direction, when such non-control light is generated, when adjacent light sources 33 emit light in different colors, light of different colors is mixed in the light guide plate. Color rendering is impaired.

  In such a case, as shown in FIG. 13B, the width of the collimating lens 34 is increased (for example, in the dimension example, the width W is increased from 10.8 mm to 11.8 mm). It is only necessary that the end be closer to the light exit surface 36 and that the light ray coming out from the end of the exit window of the light source 33 is in contact with the through hole 39 and reflected by the light reflecting wall 38. By so doing, the generation of non-control light can be suppressed, and the light beam L4 as described above can be converted into parallel light. Moreover, you may enable it to suppress non-control light by changing the design of the shape of the light reflection wall 38 or the through-hole 39. FIG.

  FIG. 14 is a simulation of the trajectory of light emitted from the light source 33. From this figure, it can be seen that the light emitted from the light exit surface 36 is fairly well collimated even if it is not completely parallel light.

  FIG. 15 is a perspective view showing the surface light source device 61 according to Embodiment 1 of the present invention, and FIG. 16 is a plan view of the surface light source device 61. The surface light source device 61 includes the light guide plate 62 and the collimated light source 31 of the first embodiment. The light guide plate 62 is injection-molded with a transparent resin having a high refractive index, guides light incident from the light incident end surface 63c, and reflects light with a light emission pattern provided at an appropriate location on the back surface 63a. Light is emitted from the emission surface 63b.

  The collimating lens array 32 and the light guide plate 62 are molded products of transparent resin having the same refractive index. The collimating lens array 32 is bonded to the light incident end surface 63c of the light guide plate 62 so that air is not caught between the light exit surface 36 and the light incident end surface 63c of the light guide plate 62. For example, the light exit surface 36 of the collimator lens array 32 is applied to the light incident end surface 63 c of the light guide plate 62 using a transparent ultraviolet (UV) curable optical adhesive having the same refractive index as that of the collimator lens array 32 and the light guide plate 62. Glued. Alternatively, the light exit surface 36 of the collimator lens array 32 may be attached to the light incident end surface 63 c of the light guide plate 62 using optical oil having the same refractive index as that of the collimator lens array 32 and the light guide plate 62.

  Therefore, in this surface light source device 61, the substantially collimated light emitted from the collimated light source 31 enters the light guide plate 62 from the light incident end face 63c. The light that has entered the light guide plate 62 is guided in the light guide plate 62 substantially along the X-axis direction, and individually emits light in front of each collimated light source 31. For example, when each light source 33 emits light in a different color, the light guide plate 62 emits light in a divided manner for each color, so that the surface light source device 61 can have color rendering properties and performance.

  Further, in this surface light source device 61, since the through hole 39 for collimating the light is provided between the light incident surface 35 and the light exit surface 36, the collimated light source 31 is joined to the surface light source device 61. Even if integrated, the shape of the through hole 39 is not impaired. Therefore, luminance unevenness as in the conventional example can be eliminated.

  FIG. 17 is a diagram illustrating a result of measuring the directivity characteristics at the end portion of the light guide plate in front of the light source that is turned on (for example, an E portion in FIG. 16). The horizontal axis indicates an angle measured from the X-axis direction, and the vertical axis indicates luminance. Moreover, a broken line shows the case of the prior art example of FIG. 3, and a solid line shows the case of the surface light source device 61 of the first embodiment. According to FIG. 17, both the conventional example and the first embodiment show almost the same directivity characteristics, and the directivity half-value angle in the width direction is about 6 degrees.

  FIG. 18 is a diagram illustrating a result of measuring the directivity characteristics at the end portion of the light guide plate in the middle front of the light sources that are lit (for example, F portion in FIG. 16). The horizontal axis indicates an angle measured from the X-axis direction, and the vertical axis indicates luminance. Moreover, a broken line shows the case of the conventional example of FIG. 3, and a solid line shows the case of the surface light source device 61 of the first embodiment. As can be seen from FIG. 18, in the case of the conventional example, two large luminance peaks are shown around ± 10 degrees, and noticeable luminance unevenness is observed. On the other hand, in the case of the first embodiment, peaks are also seen on both sides of the peak in the X-axis direction (angle 0 °), but it is considerably smaller than the conventional example, and unevenness in luminance is reduced. .

  FIG. 19A is a diagram showing the luminance distribution during light emission at the end portion of the light guide plate in the surface light source device of the conventional example as shown in FIG. 3 (a light source and a collimator lens are added to the photograph of the light guide plate). . FIG. 19B is a diagram showing the luminance distribution during light emission at the end of the light guide plate in the surface light source device 61 of Embodiment 1 of the present invention (a light source and a collimator lens added to a photograph of the light guide plate). It is. In the observation regions shown in FIGS. 19A and 19B, the width direction (Y-axis direction) is the width of two collimating lenses (21.6 mm), and the length direction (X-axis direction) is measured from the light incident end face. It is a rectangular area with a length of 45 mm.

In the region of 30 mm or less measured from the light incident end face, the luminance unevenness of the conventional example obtained from FIG. 19A is about 50%, whereas the luminance unevenness of Embodiment 1 obtained from FIG. 19B is about 80%. Thus, the uneven brightness is improved by the first embodiment. Further, in the region of 30 mm or more measured from the light incident end face, the luminance unevenness of the conventional example obtained from FIG. 19A and the luminance unevenness of Embodiment 1 obtained from FIG. 19B are both about 80%. This is because, in the region of 30 mm or more from the light incident end face, the luminance unevenness is not large even in the conventional example. The brightness unevenness here is
[(Minimum luminance) / (Maximum luminance)] x 100%
Is defined by

  FIG. 20 shows the change in luminance along the Y-axis direction at a position 10 mm from the light incident end face based on FIGS. 19A and 19B. The horizontal axis indicates the position in the Y-axis direction for two collimating lenses, and the vertical axis indicates the luminance. Further, the broken line indicates the luminance distribution of the conventional example obtained based on FIG. 19A, and the solid line indicates the luminance distribution of the first embodiment obtained based on FIG. 19B. Also from FIG. 20, the effect of improving luminance unevenness according to the first embodiment of the present invention is clear.

  Next, regarding color unevenness, in the conventional example, the opening length D is about 4 mm at the central portion of the through hole 22, whereas in Embodiment 1, the opening length D is at the central portion of the through hole 39. Therefore, in the first embodiment, light leakage from the through hole 39 can be reduced as compared with the conventional example, thereby suppressing the occurrence of color unevenness.

(Embodiment 2)
FIG. 21A is a plan view showing a collimated light source 71 according to Embodiment 2 of the present invention. FIG. 21B is a cross-sectional view of the collimated light source 71. This collimated light source 71 is composed of one light source 33 and one independent collimating lens 34. Since the collimating lens 34 of the second embodiment also has the same shape and structure as the collimating lens 34 constituting a part of the collimating lens array 32 of the first embodiment, the details are omitted. However, the collimating lens 34 according to the second embodiment is different from the collimating lens 34 according to the first embodiment in that the light reflecting walls 38 extend from both ends of the light incident surface 35 to the light exit surface 36.

  FIG. 22 is a plan view of a surface light source device 72 according to Embodiment 2 of the present invention. In the surface light source device 72, a plurality of collimated light sources 71 are arranged along the light incident end surface 63 c of the light guide plate 62, and the light exit surface 36 of the collimator lens 34 of each collimated light source 71 is the light incident end surface of the light guide plate 62. 63c is joined.

  In the surface light source device 72 as in the second embodiment, since each collimator lens 34 is independent, the light in the collimator lens 34 is prevented from leaking into the adjacent collimator lens 34 and mixing light of different colors. Can do.

(Embodiment 3)
FIG. 23 is a plan view showing a surface light source device 81 according to Embodiment 3 of the present invention. In this surface light source device 81, a plurality of collimating lenses 34 (collimating lens array 32) having a structure as described in the first embodiment and a light guide plate 62 are integrally formed by injection molding.

  Further, in this surface light source device 81, when the collimating lens 34 and the light guide plate 62 are viewed from the side, the end (point J shown in FIG. 23) of the light reflecting wall 38 far from the light incident surface 35 is the through hole 39. Is located farther from the light incident surface 35 than the end far from the light incident surface 35 (point K shown in FIG. 23). According to such a configuration, light that does not pass through the through hole 39 can be more reliably reflected forward by the light reflecting wall 38.

  In this surface light source device 81, since the plurality of collimating lenses 34 and the light guide plate 62 are integrally molded, the labor for assembling can be saved and the mass productivity can be improved. Further, there is no possibility that a positional shift occurs between the collimating lens 34 and the light guide plate 62.

DESCRIPTION OF SYMBOLS 31 Collimated light source 32 Collimating lens array 33 Light source 34 Collimating lens 35 Light incident surface 36 Light emitting surface 37 Diffusion pattern area 38 Light reflection wall 39 Through hole 42 First light refraction surface 43 Second light refraction surface 47, 49 Diffusion pattern 61 Surface light source Device 62 Light guide plate 63c Light incident end surface 71 Collimated light source 72 Surface light source device 81 Surface light source device

Claims (12)

A collimated light source having a plurality of light sources, a plurality of collimating lenses for emitting collimated the light emitted from the light source,
The collimating lenses are respectively
A light incident surface for introducing light from the light source;
A light exit surface located on the opposite side of the light entrance surface;
A light reflecting wall that extends from both sides of the light incident surface toward the light exit surface and reflects light introduced from the light incident surface;
A through hole formed in the middle of the light incident surface and the light exit surface and penetrating in the thickness direction of the collimating lens;
Before for collimating the light passing through the through-holes are introduced from the light incident surface, and a light refracting surface formed on an edge of the through hole,
The collimating light source , wherein the plurality of collimating lenses are arranged side by side in the width direction, and adjacent collimating lenses have a part of side surfaces continuous with each other .   The distance between the light refracting surface near the light incident surface and the light refracting surface far from the light incident surface of the edge of the through hole is greater than the both end portions of the through hole at the center of the through hole. The collimated light source according to claim 1, wherein the collimated light source is small.   2. The collimator according to claim 1, wherein a light refracting surface closer to the light incident surface in an edge of the through hole is configured by a curved surface, a curved surface in an arc shape, or a plurality of planes. light source.   4. The collimator according to claim 3, wherein a light refracting surface closer to the light incident surface in an edge of the through hole swells so that a central portion projects toward the inside of the through hole. light source.   The light refracting surface on the side farther from the light incident surface of the edge of the through hole is constituted by a plane parallel to the light exit surface and an inclined surface inclined with respect to the light exit surface, The collimated light source according to claim 3. The center part of the light refracting surface on the side far from the light incident surface among the edges of the through hole is a plane parallel to the light emitting surface,
Of the edges of the through-holes, on both sides of the light refracting surface far from the light incident surface, an end close to the central portion is close to the light incident surface, and an end far from the central portion is far from the light incident surface. The collimated light source according to claim 5, wherein the collimated light source is an inclined surface that is inclined as follows.   The collimated light source according to claim 1, wherein the light reflecting wall is configured by a curved surface or a plurality of flat surfaces bulging toward the outside of the collimating lens.   The collimating light source according to claim 1, wherein the light incident surface has a region where a diffusion pattern is provided and a flat region where no diffusion pattern is provided.   The collimating light source according to claim 8, wherein the diffusion pattern is a concave groove or a ridge extending in a thickness direction of the collimating lens. A light guide plate consists of a collimated light source according to claim 1 which is disposed along the light incident end face of the light guide plate, joined or integrally formed light exit surface of the collimating light source to the light incident end face of the light guide plate A surface light source device. A plurality of light sources, a light guide plate, and a plurality of collimating lenses that are formed integrally with an end portion of the light guide plate and collimate the light emitted from the light source so as to enter the light guide plate. A surface light source device,
A member in which a plurality of the collimating lenses and the light guide plate are integrated,
A light incident surface for introducing light from the light source;
A light reflecting wall that extends from both sides of the light incident surface toward the light guide plate and reflects light introduced from the light incident surface;
A through-hole penetrating in the thickness direction of the collimating lens;
A light refracting surface formed on an edge of the through hole for collimating light introduced from the light incident surface and passing through the through hole;
Equipped with a,
The surface light source device , wherein the plurality of collimating lenses are arranged side by side in the width direction, and adjacent collimating lenses have a part of side surfaces continuous with each other . When viewed from the side, the end of the light reflecting wall far from the light incident surface is located farther from the light incident surface than the end of the through hole far from the light incident surface. The surface light source device according to claim 11 , wherein the surface light source device is a feature.

Images