JP4720077B2 - Surface emitting device - Google Patents

Description

  The present invention relates to a surface light-emitting device that emits light in a planar shape by causing light from an LED element that is a point light source to enter from an incident end surface of a light guide plate, propagate through the light guide plate, and emit the light from the entire surface.

  2. Description of the Related Art In recent years, surface light emitting devices that emit light from LED elements, which are point light sources, in a planar shape have been used as light sources such as liquid crystal backlights. The light emitting device is configured to allow light from the light emitting diode to enter from the light incident end face of the light guide plate and to emit light from the entire light emitting surface of the light guide plate. In this light emitting device, it is important to output light uniformly from the light emitting surface, and various structures have been proposed to achieve this uniformity. An example of a surface light-emitting device that realizes this uniformity is disclosed in, for example, Patent Document 1.

  The surface light-emitting device disclosed in Patent Document 1 is characterized by a light guide plate. In claim 1, the light emission from the light source is emitted from the first main surface of the light guide. In the apparatus, the light guide has a plurality of cutouts having different shapes on one end surface of the light source that faces the light emission portion of the light source, and the plurality of cutouts are respectively the centers of the surfaces that face the light emission portion of the light emission portion. The angle formed between the first surface, which increases with the one end surface of the light guide as it moves away from the light source, and the end surface of the light guide, as it moves away from the center of the surface facing the emission surface of the light emitting unit, decreases. And the second surface. ”.

JP 2002-42534 A

However, at the present time when surface light emitting devices are widely used, more uniform surface light emission is required.
In view of the above, an object of the present invention is to provide a surface light emitting device that is more excellent in uniformity.

A surface light emitting device comprising: a light source having a semiconductor light emitting element; and a light guide plate that has a light emitting surface and an incident end surface and outputs light from the light source incident from the incident end surface from the light emitting surface. A light entrance part that diffuses the incident light composed of a plurality of cut-out prisms at a position facing the light source, and has a flat part at a position facing the light emission center of the light source in the light entrance part, The distance between the two adjacent cutout prisms located on the left and right sides with the flat part as the center is different from the interval between the two cutout prisms adjacent on the inner side, and the angle formed between the inner incident surface and the incident end surface is The feature is that the notch prism located farther from the center becomes smaller .

In the surface light emitting device according to the present invention, it is preferable that, in the light incident portion, the interval between the two notch prisms adjacent on the outside is wider than the interval between the two notch prisms adjacent on the inside.
Since the surface light-emitting device according to the present invention configured as described above can effectively diffuse the incident light, more uniform surface light emission is possible.

  In the surface light emitting device according to the present invention, the notch prism may be a notch formed in a triangular prism shape on the incident end surface, or may be a notch formed in a triangular pyramid shape.

  In the surface light emitting device according to the present invention, it is preferable that the notch prism is set so that the plurality of notch prisms are symmetrical from the center of the light entrance portion in the light entrance portion.

  The surface light emitting device according to the present invention can provide a surface light emitting device with high uniformity on the light emitting surface.

Hereinafter, a surface light emitting device according to an embodiment of the present invention will be described with reference to the drawings.
The surface light-emitting device according to the present embodiment is a surface light-emitting device that includes a light source and a light guide plate that has a light-emitting surface and an incident end surface and outputs light from the light source incident from the incident end surface from the light-emitting surface. Thus, the light guide plate has a feature.
More specifically, the light guide plate of the surface light emitting device of the present embodiment is a light guide plate of the surface light emitting device for uniformly emitting light from the point light source incident from the incident end surface 3 from the entire light emitting surface. Thus, the structure of the light incident portions 12a, 12b, and 12c is characteristic.
Here, the light incident portion is provided opposite to the light source at the incident end face, diffuses light from the light source and enters the light guide plate, and is generally constituted by a plurality of cutout prisms.

(Whole structure of light guide plate of embodiment)
As shown in FIG. 1, the light guide plate 1 of the present embodiment has a light emitting surface 1 as one main surface, an incident side end surface 11a, an opposite end surface 11b facing the incident side end surface, and side surfaces 11c, 11d. In addition, an incident end face 3 is provided separately from the incident end face 11a. The incident end face 3 is constituted by an end face of the light introducing part 12 formed on the incident side end face 11 a, and light incident parts 12 a, 12 b, 12 c are formed on the incident end face 3. As shown in FIG. 1, the light introducing portion 12 has a trapezoidal planar shape, and the incident end surface 3 is an end surface corresponding to the upper base of the trapezoid.
The light introduction part 12 is a part that diffuses and introduces light into the main part of the light guide plate 1, and the light emitting surface 11 of the light guide plate 1 is a part located between the incident side end face 11 a and the opposing end face 11 b. Is done.
The light guide plate of the present invention is not limited to the configuration shown in FIG. 1, and even when the light introducing portion 12 is not formed, the incident side end surface 11a is used as the incident end surface, and the incident side end surface 11a is connected to the light incident portion 12a. , 12b, 12c may be formed directly.

(Light incident parts 12a, 12b, 12c)
This embodiment of the light guide plate which is formed in the light incident portion 12a, 12b, 12c, respectively, as shown in FIG. 2, a plurality of cut that Kirikakare the triangular prism respectively outs prism _{P0, P R k (k =} 1 , 2, 3... N), P _L k (k = 1, 2, 3... _M ), but the point light source has the following unique structure not found in the conventional example. 2 makes it possible to uniformly diffuse the light incident from the entire light emitting surface 11, and realizes extremely high uniformity on the light emitting surface 11. In the present embodiment, the light emission center of the point light source 2 is arranged at the center of the light incident portions 12a, 12b, 12c. Further, when viewed from the light emitting surface of the light guide plate, the shape of the central notch prism P0 arranged at the center of the light incident portions 12a, 12b, 12c is directed to the directivity of the light source such as an isosceles triangle shape or an equilateral triangle shape. Accordingly, it can be suitably set.
Note that the position on the incident end face of the light guide plate where the angle, notch depth, width, interval, etc. of the notch prism are determined is not limited in the present invention. In particular, in this specification, a notch prism cut into a triangular prism shape will be described using the angle, notch depth, width, interval, and the like of the notch prism on the light emitting surface (upper surface). Further, in the present specification, notched prisms P _R k (k = 1, 2, 3... N), P _L k (k = 1, 2, 3... _M ) other than the center notched prism P0. In particular, the notch prisms that are spaced apart from each other are described as the separation prisms, but the portions that are simply described as the notch prisms may also include the concept of the separation prisms.

(1) Spacing between adjacent notch prisms In the present invention, first, the prism positions are set so that the notch prisms PRk and PLk located on the outer side with the center notch prism P0 as the center have a wider spacing between adjacent prisms. Is set.
That is, the light incident portion 12a of the present embodiment, 12b, 12c (hereinafter,. Simply indicated by reference numeral 12 when the representatively shown), as shown in FIG. 3, the distance _D R (k between prisms, k + 1), D _L (k, k + 1) becomes D _R (0,1) <D _R (1,2) <D _R (2,3)... and D _L (0,1) <D _L ( 1, 2) <D _L (2,3)...
Here, the distance D _R (k, k + 1) between the prisms is between the notch prism P _R k located on the right side of the central prism P 0 and the notch prism P _R k + 1 located on the outer side adjacent thereto. The distance between the prisms D _L (k, k + 1) is the distance between the k-th notch prism PLk located on the left side of the central prism P0 and the notch prism P _L k + 1 located on the outer side adjacent thereto. Indicates.

As shown in FIG. 4, the light incident part 12 configured as described above can spread light more effectively and enter the light guide plate 1.
That is, as shown in FIG. 4, the light L1 emitted from the light source, for notch prism P _{L k} is in a position away from the light emission center of the light source, with respect to the incident end surface 3 as the distance from the emission center is large Light is incident into the light guide plate obliquely so that the incident angle becomes large.
Therefore, as in this embodiment, when the notch distance of the prism P _{L k} + 1 adjacent to the notch prism P _{L k} and the outer is located away from the light emission center of the light source is set to be large, notch prism P _L k The rate at which the light incident from the outer incident surface F _Lo (k) is reflected by the inner incident surface F _Li (k + 1) of the notch prism P _L k + 1 can be reduced.

  On the other hand, as in the conventional example, the distance between a pair of adjacent notch prisms located away from the light emission center of the light source is set in the same manner as the distance between the notch prisms (distance between notch prisms). The light L2 incident from the outer incident surface of one notch prism between the pair of notch prisms located at positions away from the light emission center of the light source, and the inner side of the other notch prism. The ratio reflected by the incident surface is increased (FIG. 5).

  In other words, in the present invention, the interval between the adjacent cut-out prisms is such that light incident from the outer incident surface of the cut-out prism (one cut-out prism) located inside the cut-out prism is the other cut-out prism. Is set in accordance with the distance from the light emission center of the pair of adjacent notch prisms so that the ratio of reflection by the inner entrance surface of the light source becomes smaller.

(2) Angles of the outer incident surface and the inner incident surface with respect to the incident end surface in each notch prism Further, in the light incident portion 12 of the light guide plate of the present embodiment, as a more preferable form, the outer incident surface in each notch prism The angles of the surface and the inner incident surface with respect to the incident end surface 3 are set as follows.
That is, in the light incident part 12 of the present embodiment, the angle between the outer incident surface and the surface perpendicular to the incident end surface 3 becomes smaller as the notched prism located on the outer side, and the incident end surface 3 of the inner incident surface. The angle with the surface perpendicular to is set to be large.
In the present specification, when the angles of the outer incident surface and the inner incident surface are indicated by the angle with respect to the incident end surface 3, the angle is indicated by the inner angle in the triangular section of the notch prism. Therefore, when the above-described characteristics of the outer incident surface and the inner incident surface are expressed by the angle with respect to the incident end surface, the angle formed between the outer incident surface and the incident end surface becomes larger as the notched prism located away from the central notch prism P0. In other words, the angle formed by the inner incident surface and the incident end surface is set to be smaller as the notch prism located away from the center notch prism.

3, when the angle of the incident surface of the central notch prism P0 with respect to the plane perpendicular to the incident end surface 3 is θc, the notched prisms P _L 1, P _L 2, P _L 3. .. Angles θ _Li (1), θ _Li (2), θ _Li (3),... Of each inner incident surface F _Li (1), F _Li (2), F _Li (3). Is set so as to satisfy θc <θ _Li (1) <θ _Li (2) <θ _Li (3)..., And notches prisms P _R 1, P _R 2, P _R 3. The angles θ _Ri (1), θ _Ri (2), θ _Ri (3),... Of each inner entrance surface F _Ri (1), F _Ri (2), F _Ri (3). <Θ _Ri (1) <θ _Ri (2) <θ _Ri (3)...

Further, angles θ _Lo (1) of the outer incident surfaces F _Lo (1), F _Lo (2), F _Lo (3)... Of the notched prisms P _L 1, P _L 2, P _L 3. ), Θ _Lo (2), θ _Lo (3),... Are set so as to satisfy θc> θ _Lo (1)> θ _Lo (2)> θ _Lo (3). Angles θ _Ro (1), θ of the outer incident surfaces F _Ro (1), F _Ro (2), F _Ro (3)... Of the notch prisms P _R 1, P _R 2, P _R 3. _Ro (2), θ _Ro (3),... Are set so as to satisfy θc> θ _Ro (1)> θ _Ro (2)> θ _Ro (3).

As shown in FIG. 6, the light incident section 12 configured as described above can spread light more effectively and enter the light guide plate 1.
That is, as shown in FIG. 6, the light L1 from the light source emitted in the direction of the notch prism P _L k located away from the light emission center of the light source is reflected on the outer incident surface F _Lo of the notch prism P _L k. When the light is incident from (k), the probability that the incident light L3 is reflected by the inner incident surface F _Li (k + 1) of the adjacent notch prism P _L k + 1 can be reduced (on the inner incident surface of each notch prism). When the angle and the angle of the outer incident surface are not set as described above, for example, when the angle of the inner incident surface and the angle of the outer incident surface are set to be the same in all the prisms, a dotted line in FIG. As shown by (2), the probability of being reflected by the inner incident surface F _Li (k + 1) of the adjacent cut-out prism P _L k + 1 increases.)

  In other words, according to the present invention, the angle of the inner incident surface and the angle of the outer incident surface of the notch prism are set so that the angles of the notch prisms (one notch prism) that are located inside the pair of adjacent notch prisms are outside incident. This is set according to the distance from the emission center of the two notch prisms so that the ratio of the light incident from the surface being reflected by the inner entrance surface of the other notch prism is reduced.

(3) Angle formed by the outer incident surface and the inner incident surface in each notch prism Further, the light incident section 12 of the present embodiment is separated from the light emission center as shown in FIGS. 10, 11, 18, and 19. Accordingly, the angle of the notch prisms by the outer incident surfaces F _Lo (k), F _Ro (k) and the inner incident surfaces F _Li (k), F _Ri (k) may be set to change. Preferably, in the light incident part 12 of the present embodiment, as shown in FIGS. 11 and 19, from the inner incident surface F _Ri (k) and the outer incident surface F _Ro (k) of the notch prism P _R k. becomes the angle [theta] P _R k, are each set to satisfy the _{P0 <P R 1 <P R} 2 <P R 3 ···, notches prism _{P L} k of the inner entrance surface _F Li (k) and an outer The angles θP _L k formed from the incident surface F _Lo (k) are set so as to satisfy P0 <P _L 1 <P _L 2 <P _L 3. In addition, when the opening w of the notch prism has the same width in accordance with such an angle setting, the notch prism notch depth (from the top of the notch prism outer incident surface and inner incident surface). The height h to the incident end face is h0>hR1>hR2> hR3... And h0>hL1>hL2> hL3. Note that the angle θ _Ri (k + 1) formed between the inner incident surfaces F _Ri (k + 1) and F _Li (k + 1) of the notch prism and a plane perpendicular to the incident end surfaces D _R (k, k + 1) and D _L (k, k + 1). ), Θ _Li (k + 1), and a plane perpendicular to the outer incident surfaces F _Ro (k + 1) and F _Lo (k + 1) and the incident end surfaces D _R (k + 1, k + 2) and D _L (k + 1, k + 2) of the notch prism. The angles θ _Ro (k + 1) and θ _Lo (k + 1) formed by are the same.

The light incident part 12 configured as described above can also effectively make light incident in the lateral direction (perpendicular to the optical axis of the light source).
That is, in the light incident part 12 of the present embodiment, the cutout prism angles θP _L k and θP _R k are set to be larger as the cutout prism located on the outer side is larger. Since the notch depth is reduced, in a pair of adjacent notch prisms, the ratio of the light incident from the outside incident surface of the notch prism located inside is reflected by the inside entrance surface of the other notch prism is small. Become.

Further, as described above, the distance D _L between adjacent prism _{(k, k + 1),} D R (k, k + 1) to change the, in particular adjacent higher notch prism located outside around the central cutout prism prism In this embodiment, by changing the interval between adjacent prisms so that the interval between them is widened, the angle of the notch prism is set to be smaller as the notch prism located on the outer side becomes smaller. The effects of the invention can be obtained. That is, in the light incident part 12 of the present embodiment, as shown in FIG. 10, the angle θP _{R formed} by the inner incident surface F _Ri (k) and the outer incident surface F _Ro (k) of the notch prism P _R k. k, are set so as to satisfy P0> P _R 1> P _R 2> P _R 3... respectively, and the inner incident surface F _Li (k) and the outer incident surface F _{Lo of the} notch prism P _L k are set. The angle θP _L k composed of (k) is set so as to satisfy P0> P _L 1> P _L 2> P _L 3. In addition, when the openings of the notch prism have the same width due to such an angle setting, the notch prism notch depth (incident from the top due to the notch prism outer incident surface and inner incident surface). height) h to the end face is a _{h0 <h R 1 <h R} 2 <h R 3 ··· and _{h0 <h L 1 <h L} 2 <h L 3 ···. The angles θ _Ri (k + 1), θ _Li formed by the inner entrance surfaces F _Ri (k + 1), F _Li (k + 1) of the notch prism and the incident end surfaces D _R (k, k + 1), D _L (k, k + 1). (K + 1) and the angle θ _Ro (k + 1) formed between the outer incident surfaces F _Ro (k + 1) and F _Lo (k + 1) and the incident end surfaces D _R (k + 1, k + 2) and D _L (k + 1, k + 2) of the notch prism. , Θ _Lo (k + 1) are the same.

Thus, notch prism P _{R k} is located away from the center cutout prism P0, P L _k as the notch depth h _{R k,} even if h L _k is increased, the notch prism adjacent intervals Since D _L (k, k + 1) and D _R (k, k + 1) are arranged such that the distance between the notch prisms located on the outer side with the center notch prism as the center is increased, the inside incidence of the outer notch prism is increased. It is possible to prevent the light entering from the outer incident surface of the adjacent notch prism from being blocked by the surface. Further, as the angles θP _L k and θP _R k of the notch prisms located on the outer side become smaller, as shown in FIG. 26, the angle is lower than the normal of the outer incident surfaces F _Lo and F _Ro (the center of the light incident portion). Since light is refracted closer to the normal by making light incident from the incident end face D _L (k, k + 1), D _R (k, k + 1) side) further away from the optical axis, the direction is substantially perpendicular to the optical axis. The light can be refracted and expanded. On the other hand, as shown in FIG. 27, when the angles θPLk and θPRk of the notch prisms located on the outside increase, the incident end face D _L closer to the vertical of the outer incident surfaces F _Lo and F _Ro (closer from the center of the light incident portion) Since light enters from (k−1, k), D _R (k−1, k) side), it is difficult to refract the light in a direction substantially perpendicular to the optical axis.

(4) Width of each cut-out prism opening The light incident section 12 of the present embodiment is similar in shape to each of the plurality of cut-out prisms as shown in FIGS. 14, 15, 22, and 23. And the width of the opening of the notch prism may be set to change.
Preferably, the light entering portion 12 of the present embodiment, FIG. 14, the cutout prism P _{R k} as shown in FIG. 23, P L _k is the left and right sides around the central cutout prism P0, the center cutout prism the distance from P0, becomes smaller in similar shape, _w0 is the opening w of the notch _{prism> w R 1> w R 2} > w R 3 ··· and _{w0> w L 1> w L} 2> w L 3 Set to satisfy. Further, the notch depth h of the notch prism satisfies h0> h _R 1> h _R 2> h _R 3... And h0> h _L 1> h _L 2> h _L 3. Set.

Light can be effectively spread also with respect to the light incident portion configured as described above. That is, with the central notch prism P0 as the center, the left and right sides are reduced in a similar shape, so that in the pair of adjacent notch prisms, the light incident from the outer incident surface of the notch prism located on the inner side becomes the other The proportion reflected by the inner entrance surface of the notch prism is reduced.
Furthermore, as described above, by providing an interval between adjacent notch prisms, in particular, by changing the interval between adjacent prisms so that the notch prism located on the outer side with the center notch prism P0 as the center is changed, Furthermore, the effect can be enhanced. In the case of the present embodiment, as shown in FIG. 14, the distances D _L (k, k + 1) and D _L between the notch prisms PLk and PRk that are located outward from the center notch prism P0 as the center. _{Even if R} (k, k + 1) is set to be narrow, a good effect can be obtained. That is, in a pair of adjacent notch prisms, the ratio of light incident from the outer incident surface of the notch prism positioned on the inner side can be relatively reduced by the inner incident surface of the other notch prism. .

Further, as shown in FIG. 15, the distance between adjacent prisms is increased as the distance from the light emission center increases, so that it can be set to have a similar shape on both the left and right sides with the center notch prism as the center. That is, in the light incident part 12 of the present embodiment, the notch prisms P _R k and P _L k are opened on the notch prism so that the notch prisms P _R k and P _L k increase in a similar shape on both the left and right sides with the center notch prism P0 as the center. parts w is set so as to satisfy _{w0 <w R 1 <w R} 2 <w R 3 ··· and _{w0 <w L 1 <w L} 2 <w L 3 ···. Further, the notch depth h of the notch prism satisfies h0 <h _R 1 <h _R 2 <h _R 3... And h0 <h _L 1 <h _L 2 <h _L 3. Set.
As described above, when the center cutout prism P0 is the center and the left and right sides are enlarged in a similar shape, the light incident from the outer incident surface of the cutout prism located on the inner side is adjacent to the other pair of cutout prisms. Although the ratio of reflection by the inner entrance surface of the notch prism increases, the ratio of reflected light can be reduced by gradually increasing the distance between the notch prisms with the center notch prism as the center. it can. Furthermore, in the case of such a form, the outer notch prism apart from the center notch prism located on the dark side between the corners of the light guide plate and the light source has a larger shape, so that the outer notch prism Since more light can be incident on the outer incident surface, it is possible to effectively spread the light in a direction substantially perpendicular to the optical axis.

(5) Relationship between the width of the central notch prism opening and the spacing between the notch prism adjacent to the center notch prism The light incident part of the present embodiment is positioned facing the light emission center as shown in FIG. distance between the prism _P R 1, _{P L} 1 and the central cutout prism P0 notch the adjacent width of the opening w0 of the central cutout prism P0 and a central notch prism to _{D R (0,1), D L} ( 0,1) may be substantially the same. Further, the width w0 of the opening of the center cutout prism P0, the prism _P R 1 two notches adjacent to the central cutout prism, _{P L} 1 and the central notch spacing _D R of the prism P0 (0, 1) , D _L (0, 1) can be made larger, but by making it smaller as shown in FIG. 17, it is possible to obtain more uniform surface light emission.
Since the light incident on the central notch prism P0 travels in a direction substantially perpendicular to the optical axis from the light source, if the light is changed in a direction substantially perpendicular to the optical axis, the light is incident on the front end of the light guide plate. Since the amount of light reaching a certain facing end face 11b is reduced, there are cases where the vicinity of the light source becomes significantly brighter than other parts, and thus preferable surface emission cannot be obtained. Therefore, as described above, by making the width w0 of the central notch prism opening substantially equal to or smaller than the interval between the notch prisms P _L 1 and P _R 1 adjacent to the center notch prism P0, Such a problem can be avoided.

(6) Flat part disposed opposite to the light emission center The light guide plate of the present embodiment described above has a flat part D between two adjacent cutout prisms in the light incident part 12 of the light guide plate of the present embodiment. (0) can also be arranged facing the emission center. That is, as shown in FIGS. 9, 12, 13, 20, 21, 24, and 25, in the light incident portion 12, the central notch prism P <b> 0 does not exist, and the central notch prism P <b> 0 is replaced. a plurality of notches prism P _{R k,} is P L _k are respectively disposed on left and right sides around the flat portion D (0) to be placed on. In such a case, the notch prisms P _L 1 and P _R 1 are disposed adjacent to the flat portion D (0).
By adopting such a configuration, the flat portion D (0) is arranged in the light incident portion 12 facing the light emission center, so that the light traveling in the optical axis direction from the light source reaches the tip portion of the light guide plate. Can lead. Furthermore, by arranging the notched prisms P _R k and P _L k on the left and right sides with the flat portion D (0) as the center, light having a large incident angle with respect to the incident end face can be efficiently spread in the light guide plate width direction. Can do. In addition, light having a large incident angle can be spread in the width direction of the light guide plate at the incident end face 3 that is relatively far from the light emission center.
Note that the width of the flat portion D (0), which is disposed opposite to the light emission center and is made up of the incident end face of the light incident portion, takes into account the directivity, light quantity, and other light emission characteristics of the light source to obtain a desired light emission surface. Can be determined as appropriate.

As described above, the light guide plate according to the present embodiment has the notch prisms P _R k and P _L k located on the outer side with respect to the center notch prism P 0 in the light incident portion 12. Since the prism position is set so as to widen the incident light, incident light can be effectively diffused and incident, and a dark part (FIG. 1) formed near the incident end face 3 of the light emitting surface 11. The portion indicated by the broken line with the reference numeral 50 can be made extremely small.

  Further, the light guide plate of the present embodiment is set such that, in the light incident portion 12, the angle formed between the outer incident surface and the incident end surface is larger as the notched prism located away from the center notched prism P0. The angle formed between the inner entrance surface and the entrance end surface is set to be smaller as the notch prism located farther from the center notch prism, so that the incident light can be diffused and entered more effectively. The dark part formed near the incident end face 3 of the light emitting surface 11 can be made even smaller.

  In the light guide plate according to the present embodiment, the angle of the notched prism formed by the outer incident surface and the inner incident surface is changed in the light incident portion 12, and preferably the notched prism formed by the outer incident surface and the inner incident surface. The angle may be set so as to increase as the notch prism located away from the center notch prism P0. Even in such a form, the incident light can be effectively expanded without being blocked, and a dark portion formed in the vicinity of the incident end face 3 of the light emitting surface 11 can be eliminated.

  Further, in the light guide plate of the present embodiment, the notch prisms have similar shapes in the light incident part 12, and the width of the opening of the notch prism changes, preferably away from the center notch prism P0. You may set so that the notch prism located may become small. Even in such a form, the incident light can be effectively expanded without being blocked, and a dark portion formed in the vicinity of the incident end face 3 of the light emitting surface 11 can be eliminated.

Further, the light guide plate of the present embodiment, the distance D of the light incident portion 12, a prism P _{L 1,} P R ₂ notch adjacent to the prism P0 notch width w0 and the central cutting of the opening of the center cutout prism _L (0,1) and D _R (0,1) are substantially the same, or the width w0 of the opening of the central notch prism is the distance D _L (0,1) between the central notch prism and the adjacent notch prism. If it is set to be smaller than D _R (0, 1), a light guide plate that can more effectively obtain uniform surface light emission can be obtained.

  In the light guide plate of the present embodiment, in the light incident part 12, a flat part D (0) is provided at the center of the light incident part facing the light emission center, and the prisms are cut out on both the left and right sides with the flat part as the center. Is set so that a sufficient amount of light traveling straight in the optical axis direction from the light source can be guided to the opposing end surface of the light guide plate tip.

  As described above, the light-emitting device of the present invention selects the most appropriate shape of the notch prism and the best interval in accordance with the shape of the light guide plate and the directivity of the light source, thereby making the incident light more effective. Can be spread over the entire surface of the light guide plate. In this case, increasing the number of notch prisms and increasing the side walls can diffuse light more complexly and improve the uniformity of brightness, but the mold structure becomes complicated, and as a result, the mold There may be a problem that the shape of the incident end face of the light guide plate manufactured by the method becomes unstable. Therefore, it is preferable to select the shape to be used in consideration of the manufacturing conditions in addition to the required specifications depending on the purpose of use. That is, since various shapes can be selected in the present invention, which shape of the cutout is selected depends on the size of the light guide plate, the number of light sources to be used and the directivity thereof, the intended performance, It is also possible to comprehensively study and determine the restrictions on mold fabrication and molding accuracy.

Further, in the present embodiment, as a more preferable embodiment of the present invention, the light introducing portion 12 that does not constitute the light emitting surface is formed, and the light shielding portion that covers the upper surface of the light introducing portion 12 is formed.
Thereby, leakage of light from directly above the notch prism can be prevented, and the uniformity of light on the light emitting surface 11 can be improved.

Further, in the light guide plate of the present invention, a texture or prism array composed of a plurality of dots, the density of which is set so that the luminous intensity of the light emitting surface is made more uniform on one or both of the reflective surface and the light emitting surface, etc. Surface processing can also be performed. Here, the dots are a large number of concave portions or convex portions formed on the reflecting surface or the like for scattering light, and the luminance distribution on the light emitting surface can be adjusted in accordance with the density. For example, when the dot density or the area occupied by the dots is sequentially increased as the distance from the light source increases, the luminance in the light emitting surface can be made uniform. In addition, the shape of the dots is not limited to simple recesses or protrusions, but in order to more effectively scatter light, various shapes such as those where the central part of the bottom of the recesses is raised and those around the protrusions are recessed Can be applied.
The dot arrangement may be regularly arranged so as to have a predetermined density, may be arranged randomly, or may be a dot pattern obtained by combining them.

In the above embodiment, the example using the triangular prism notch prism has been described. However, the present invention is not limited to this, and may be configured using a triangular pyramid cutout prism P100 shown in FIG.
There are the following operational effects between the triangular prism cutout prism and the triangular pyramid cutout prism.
The triangular prism notch prism has a remarkable effect of diffusing light from the light source in the lateral direction (left and right).
Therefore, it is more possible to combine this triangular prism cutout prism with a configuration unique to the present application in which the prism position is set so that the interval between the adjacent cutout prisms P _R k and P _L k is wider. A good light diffusion effect can be obtained. In addition to this, the angle between the outer incident surface and the surface perpendicular to the incident end surface 3 is smaller and the angle between the inner incident surface and the surface perpendicular to the incident end surface 3 is smaller as the notched prism is located on the outer side. By adding a configuration in which the value is set to be larger, an even better light diffusion effect can be obtained.

On the other hand, the effect of diffusing light from the light source in the lateral direction (left and right) is not as remarkable in the triangular pyramid cutout prism as in the triangular prism cutout prism.
However, as shown in FIG. 7, the triangular pyramid-cut prism does not penetrate on the main surface side on the light emitting surface side, so that light can be less leaked from the main surface on the light emitting surface side.
Therefore, for example, it is suitable for a surface emitting device that does not have a space for forming the light introducing portion 12.
In addition, the triangular pyramid-cut prism itself is not as effective in diffusing light from the light source in the horizontal direction (left and right) as the triangular prism cut-out prism, but the cut-out prism located on the outer side is adjacent to the prism. Combining a configuration peculiar to the present application in which the prism position is set so that the interval between them is wide, a good light diffusion effect can be obtained.
In other words, according to the specific configuration of the present invention, the shortage of light diffusing ability of the triangular pyramid-cut prism can be compensated.

  Hereinafter, preferred materials and the like regarding each element in the surface light emitting device of the present embodiment will be described.

(Light guide plate)
As the material used for the light guide plate in the present invention, it is preferable to use a material having excellent light transmittance and moldability, and examples thereof include acrylic resin, polycarbonate resin, cycloolefin polymer, polystyrene resin, and functional norbornene resin. . These light guide plate materials have different refractive indexes, but the light diffusion can be controlled by selecting the angle and number of notched prisms formed on the incident end face of the light guide plate. Is not subject to any restrictions. Moreover, the shape of the light guide can be any shape depending on the application.

(light source)
In the surface light-emitting device of the present invention, the number of light sources may be one, or two or more. Generally, a light-emitting diode (LED element) is used. In order to position and fix the LED element and the notch prism formed on the incident end face of the light guide plate, for example, a support made of a resin molded body is used, and the light emission surface of the LED element is the light incident portion of the light guide plate. LED elements are arranged so as to face each other. The LED element has a semiconductor element and a translucent resin that covers the semiconductor element. The translucent resin absorbs light generated from the semiconductor element and generates light having a wavelength different from that of the absorbed light. The fluorescent substance to be contained can be contained. When the light generated from the semiconductor element is ultraviolet light, a phosphor that is excited by the ultraviolet light to generate ultraviolet light or visible light can be used, or a semiconductor element capable of emitting visible light may be used. Further, it may be combined with a fluorescent material capable of absorbing visible light from the semiconductor element and emitting visible light having a longer wavelength. When a semiconductor element is used in combination with a phosphor, it is possible to emit mixed colors having various tones, and color mixing can be improved by making light incident from the above-described notch prism.

(Semiconductor element)
As the semiconductor element, for example, nitride-based compound semiconductor (formula _In i _Ga j _Al k N, where, 0 ≦ i, 0 ≦ j , 0 ≦ k, i + j + k = 1) a device fabricated by using the Can be used. As nitride compound semiconductors, there are various types including InGaN and GaN doped with various impurities. This semiconductor element is formed by growing a semiconductor such as InGaN or GaN as a light emitting layer on a substrate by MOCVD or the like. Examples of the structure of the semiconductor element include a homostructure, a heterostructure, or a double heterostructure having a MIS junction, a PIN junction, or a pn junction. The nitride semiconductor layer can have various emission wavelengths depending on the material and the degree of mixed crystal. Moreover, it can also be set as the single quantum well structure and multiquantum well structure which formed the semiconductor active layer with the thin film which produces a quantum effect.

(Fluorescent substance)
The fluorescent substance used in the present invention converts the wavelength of light from the LED element as described above, and the fluorescent substance is fluorescent on the translucent resin covering the LED element placed in the support body made of a resin molded body. By containing the substance, the light emitted to the outside of the support can be converted. When the light from the LED element is high-energy short-wavelength visible light, the nitrogen-containing CaO—Al ₂ activated by a perylene-type derivative that is an organic phosphor, ZnCdS: Cu, YAG: Ce, Eu, and / or Cr. Various inorganic materials such as O ₃ —SiO ₂ are suitably used. Especially when YAG: Ce phosphor is used, light from the LED element that emits blue light depending on its content and yellow color that is partially absorbed by the light can be emitted and the white system is relatively simple. It is preferable because it can be formed with high reliability. Similarly, when a nitrogen-containing CaO—Al ₂ O ₃ —SiO ₂ phosphor activated by Eu and / or Cr is used, blue light and a complementary color by partially absorbing the light depending on its content Therefore, the white system is preferable because it can be formed relatively easily and with high reliability.

  In the above embodiment, the numbers n and m of the left and right cut-out prisms in the light incident portion are the same (n = m). However, the present invention is not limited to this, and the number of left and right cut-out prisms n and m may be different (n≈m or n ≠ m may be satisfied).

  Next, the light guide plate of the surface light emitting device according to the embodiment of the present invention will be described. However, the present invention is not limited to this.

As Example 1, the light guide plate shown in FIG.
In the light guide plate 1 of the present embodiment, the length of the incident side end face 11a and the opposite end face 11b is set to about 46 mm, and the length of the side faces 11c and 11d is set to about 34 mm, and is about 3 mm outward from the incident side end face 11a. It has a projecting incident end face 3. The incident end face 3 has a width of about 30 mm, and light incident portions 12 a, 12 b, and 12 c are formed on the incident end face 3.
Further, the light incident portions 12a, 12b, and 12c are respectively triangular prism cutout prisms P0, P _L 1, P _L 2, and P _L each having an isosceles triangular shape in which the lengths of the eleven outer incident surfaces and the inner incident surfaces are equal. _{3, P L 4, P L} 5, P R 1, P R 2, P R 3, P R 4, P R 5 by constructed, detailed shapes and positional relationship as shown in tables 1 and 2 below did.

表１中、括弧（）内に示す角度は、入射端面３に対する角度である。 [Table 1]

In Table 1, the angle shown in parentheses () is an angle with respect to the incident end face 3.

[Table 2]
(Adjacent notch prism spacing)

The width of the opening of each notch prism was 0.11 mm, and the notch depth h was 0.095 mm.
Using the light guide plate of the surface light emitting device of Example 1 configured as described above, a light emitting diode is provided to face the light incident portions 12a, 12b, and 12c to produce a surface light emitting device to emit light on the light emitting surface. As a result of observing the state, as shown in the photograph of FIG. 8 (only the vicinity of the light incident part is represented and the other part is covered with a mask), the dark part near the incident side end face can be reduced.
In this example, blasting was performed on the side of the reflecting surface of the light guide plate (the other main surface facing the light emitting surface) close to the incident side end surface (a portion at a predetermined distance from the incident side end surface).

FIG. 10 shows a schematic plan view of the light incident part of the light guide plate of the second embodiment.
In the light guide plate 1 of this embodiment, the length of the incident side end face 11a and the opposite end face 11b is set to about 46 mm, and the length of the side faces 11c and 11d is set to about 34 mm, as in the first embodiment. The incident end face 3 protrudes about 3 mm outward from 11a. The width of the incident end face 3 is about 30 mm, and light incident portions 12a, 12b, and 12c are formed on the incident end face 3.
Further, the light incident portions 12a, 12b, and 12c are respectively triangular prism cutout prisms P0, P _L 1, P _L 2, and P _L each having an isosceles triangular shape in which the lengths of the eleven outer incident surfaces and the inner incident surfaces are equal. _{3, P L 4, P L} 5, P R 1, P R 2, P R 3, P R 4, P R 5 by constructed, detailed shapes and positional relationship as shown in tables 3 and 4 below To do.

[Table 3]

[Table 4]
(Adjacent notch prism spacing)

The width of the opening of each notch prism including the center notch prism is 0.10 mm.
When the light guide plate of the surface light emitting device of Example 2 configured as described above is used, the vicinity of the incident surface side end surface and the dark portion between the light sources can be reduced.

FIG. 14 is a schematic plan view relating to a light incident portion of the light guide plate of the third embodiment.
In the light guide plate 1 of this embodiment, the length of the incident side end face 11a and the opposite end face 11b is set to about 46 mm, and the length of the side faces 11c and 11d is set to about 34 mm, as in the first embodiment. The incident end face 3 protrudes about 3 mm outward from 11a. The width of the incident end face 3 is about 30 mm, and light incident portions 12a, 12b, and 12c are formed on the incident end face 3.
The light incident portions 12a, 12b, and 12c are triangular prism cutout prisms P0, P _L 1, P _L 2, and P _L each having an isosceles triangular shape in which the lengths of the nine outer incident surfaces and the inner incident surfaces are equal. 3, P _L 4, P _R 1, P _R 2, P _R 3, P _R 4, and the detailed shape and positional relationship are as shown in Table 5 and Table 6 below.

[Table 5]

[Table 6]
(Adjacent notch prism spacing)

  By using the light guide plate of the surface light emitting device of Example 3 configured as described above, it is possible to satisfactorily reduce the vicinity of the incident side end face and the dark part between the light sources.

  The present invention relates to a light guide plate and a surface light emitting device of a surface light emitting device, and can be applied to a liquid crystal backlight, a panel meter, an indicator lamp, a surface light emitting switch, and the like.

It is a top view of an embodiment concerning the present invention. It is a perspective view which expands and shows a part of light-incidence part of embodiment. It is a top view which shows the light-incidence part of embodiment in detail. It is a schematic diagram (the 1) for demonstrating the effect of the light-incidence part of embodiment. It is the schematic diagram used as a comparison in order to demonstrate the effect of the light entrance part of embodiment. It is a schematic diagram (the 2) for demonstrating the effect of the light-incidence part of embodiment. It is a figure which shows the notch of the triangular pyramid shape which comprises the light-incidence part of the modification which concerns on this invention. It is a photograph which shows the mode of the light emission surface of the surface light-emitting device of an Example. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a top view which shows the light-incidence part of embodiment in detail. It is a schematic diagram (the 3) for demonstrating the effect of the light-incidence part of embodiment. It is the schematic diagram used as a comparison in order to demonstrate the effect of the light entrance part of embodiment.

1 ... light guide plate,
2 ... light source,
3 ... incident end face,
11 ... light emitting surface,
11a ... incident side end face,
11b ... opposing end faces 11c, 11d ... side faces,
12 ... introduction part,
12a, 12b, 12c ... light incident part,
P0: Central notch prism,
_{P R k (k = 1,2,3 ···} n) ··· right k-th notch prism,
P _L k (k = 1, 2, 3... _M ): k-th notch prism on the left side,
F (0): entrance surface of the central notch prism P0,
F _Ri (k) ... the inner entrance surface of the k-th notch prism on the right side,
F _Li (k): inner entrance surface of the left k-th notched prism,
F _Ro (k) ... the outer incident surface of the k-th notch prism on the right side,
F _Lo (k) ... the outer incident surface of the k-th notch prism on the left side,
θ _Ri (k): an angle formed by the inner incident surface of the right k-th notch prism and a surface perpendicular to the incident end surface;
θ _Li (k): an angle formed between the inner incident surface of the left k-th notch prism and a surface perpendicular to the incident end surface;
θ _Ro (k): an angle formed between the outer incident surface of the right k-th notch prism and a surface perpendicular to the incident end surface;
θ _Lo (k)... Angle formed between the outer incident surface of the left k-th notched prism and a surface perpendicular to the incident end surface.
θP0... the top angle between the outer and inner incidence surfaces of the central notch prism θP _R k... the outer incidence surface F _Ro (k) and the inner incidence surface F _Ri (k) of the right k-th notch prism. ) and the angle of the top by [theta] P _L k · · · left k th notch angle of the top by the outer entrance surface _F Lo (k) and the inner entrance surface _F Li (k) of the prism D (0) · · · ( P _R 1 and _P between _L 1) flat portion w0 · · · central cutting width _w of the opening of the lacking prism R k · · · right k-th cutting width of the opening of the lacking prism _w L k · ·・ Width h0 of the opening of the k-th notch prism on the left side ... Height (depth) of the center notch prism
h _R k: Height (depth) of the k-th notch prism on the right side
h _L k: Height (depth) of the k-th notch prism on the right side

Claims (5)

A surface light emitting device comprising: a light source having a semiconductor light emitting element; and a light guide plate that has a light emitting surface and an incident end surface and outputs light from the light source incident from the incident end surface from the light emitting surface,
The incident end surface has a light incident portion that is made up of a plurality of cutout prisms and diffuses incident light at a position facing the light source,
In the light incident part, it has a flat part at a position facing the light emission center of the light source,
The angle formed between the inner incident surface and the incident end surface is set so that the interval between the two adjacent notched prisms located on the left and right sides of the flat portion is different from the interval between the two adjacent notched prisms on the inner side. Is a surface light emitting device characterized in that it becomes smaller as the notch prism located farther from the center .   The surface emitting device according to claim 1, wherein in the light incident portion, the interval between two notch prisms adjacent on the outside is wider than the interval between two notch prisms adjacent on the inside.   The surface emitting device according to claim 1, wherein the notch prism is formed by a notch formed in a triangular prism shape at the incident end face.   The surface light emitting device according to claim 1, wherein the notch prism includes a notch formed in a triangular pyramid shape on the incident end face.   5. The surface light emitting device according to claim 1, wherein in the light incident portion, the plurality of notched prisms are set symmetrically from the center of the light incident portion.

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