JP4385057B2 - Light guide plate and flat illumination device - Google Patents

Description

In the present invention, for a light source having emitted light having an arc-shaped directivity characteristic, an arc-shaped or corrugated region corresponding to the directivity characteristic from the incident end face portion is used as a mirror surface portion so as to correspond to the directivity characteristic of the light source, In other areas, fine dot-shaped light deflecting elements are provided on the exit surface portion and the opposite exit surface portion, and on the exit surface portion and the opposite exit surface portion depending on the thickness of the light guide plate depending on the maximum refraction angle when entering the light guide plate. first a light guide plate without the optical deflecting element is at a distance from the incident end face to reach the diffusing portion at a position closer to the entrance end surface than the front surface of at least a light source opposed to the light guide plate, the light guide plate Reflectors extending to a distance where no light deflection element is provided in the direction of the exit surface, and extending to a distance where no light deflection element is provided in the direction of the exit surface, or extending to the entire counter exit surface, and these Case for storing light source, light guide plate, and reflector A flat lighting device comprising comprising a reflector from the outside of the light guide plate further comprises from the outside of the reflector in the order of the light source, reflector provided substantially equal opening to the size of the emission surface of the light source, the opening The light source part is inserted into the light source plate, and the light source and the incident end face part of the light guide plate are not in contact with each other. The amount of emitted light is suppressed in the region corresponding to the directivity characteristic of the light source, and the desired amount of emitted light is obtained in the other regions. The light emitted from the light source is not reflected when observing from the light exit surface, and the light emitted from the light exit from the light source and the light emitted from a plurality of light sources or from a plurality of light sources having different emission colors is mixed. A light guide plate that can be obtained, diffuses lateral light from the light source, reflects light returned from the light guide plate, can be returned to the light guide plate again, and avoid contact between the light source and the light guide plate In addition, the light guide plate can be sandwiched, leakage light from the light guide plate can be eliminated, and abnormal emission light due to contact between the light source and the light guide plate or non-mixing by light sources of different emission colors The present invention relates to a reflector that can avoid unnecessary emitted light and can avoid deformation of the light guide plate due to heat from the light source even during long-time use, and a flat illumination device using these light guide plates.

As a conventional light source device, in order to make a lot of radiated light enter into a light guide plate or the like, a device using a transparent material is known so as to be fitted into the light guide plate.
Furthermore, a light source device is also known in which the light source device is miniaturized so that more light sources can be used, and portions other than the light emitting portion are omitted as much as possible.

Further, since the light source used in the light source device is a semiconductor light emitting element (LED or the like) and has high directivity, light with particularly high luminance and energy value goes straight to the center position of the light guide plate, and the incident portion of the light guide plate The illumination device is configured to diffuse light when entering the light guide plate by applying a prism process having a ridge in the direction from the front surface portion to the back surface portion so as to diffuse in the incident portion so as to travel in the opposite direction It has been known.
JP-A-10-293202

  In the conventional light source device described above, in order to allow a large amount of radiated light to enter the light guide plate or the like, all of the light source plates are fitted with the light guide plate and transparent materials are used. Since the light enters the light guide plate in a state where the directivity remains as it is, the light exiting as it is reflected in the directivity is obtained. For this reason, there is a problem that light spots are generated and a problem that the use of linear light that has entered the central portion of the light guide plate is small.

  Further, since the light source used in the light source device is a semiconductor light emitting element (LED or the like) and has high directivity, light with particularly high luminance and energy value goes straight to the center position of the light guide plate, and the incident portion of the light guide plate The illumination device is configured to diffuse light when entering the light guide plate by applying a prism process having a ridge in the direction from the front surface portion to the back surface portion so as to diffuse in the incident portion so as to travel in the opposite direction Then, a diffusion effect can be obtained in the lateral direction with respect to the thickness. However, a part of the light traveling in the lateral direction leaks outside from the side surface portion of the light guide plate without being diffused in the thickness direction. Therefore, there is a problem that the amount of light emitted from the emission surface cannot be obtained as expected.

(Object of invention)
The present invention has been made to solve the above-described problems, and provides a light guide plate and a flat illumination device as described below. That is, for a light source composed of a semiconductor light-emitting element having emitted light having an arc-shaped directivity , and for a light source having this directivity, the directivity from the incident end face corresponds to the directivity of the light source. The arc-shaped or wave-shaped area is used as a mirror surface, and in other areas, fine dot-shaped light deflecting elements are provided on the exit surface and / or the opposite exit surface, and guided by the maximum refraction angle when entering the light guide plate. distance the incident and the light guide plate without the light deflector, than the front surface of at least a light source opposed to the light guide plate from the incident end face to reach the first exit surface portion and anti emitting surface portion depends on the thickness of the optical plate It has a diffusing part at a position close to the end face part, and extends to a distance where no light deflection element is provided in the direction of the exit surface part of the light guide plate, and similarly extends to a distance where no light deflection element is provided in the direction of the opposite exit face part. Extends over the entire surface Furekuta and, the light sources and the light guide plate and a reflector and such a light guide plate formed by and a case for housing a, a reflector and a planar illumination device consisting, the reflectors from outside of the light guide plate, the outer side of the reflector To the light source, the reflector is provided with an opening substantially equal to the size of the light emitting surface of the light source, the light source portion is inserted into the opening, and the light source is not in contact with the incident end surface of the light guide plate. In the area corresponding to the directivity of the light, the amount of outgoing light can be suppressed, and in other areas, the desired amount of outgoing light can be emitted, and there is no reflection of the light source when observed from the outgoing face part, and the whole outgoing face part Uniform outgoing light and mixed outgoing light can be obtained even with light from a plurality of light sources and light sources having different emission colors.
Further, it is possible to diffuse the light in the lateral direction from the light source, reflect the light returned from the light guide plate, return the light to the light guide plate again, and avoid contact between the light source and the light guide plate.
Further, the light guide plate can be sandwiched between the reflectors, and leakage light from the light guide plate can be eliminated. In addition, it is possible to avoid abnormal outgoing light due to contact between the light source and the light guide plate and unmixed outgoing light due to a plurality of light sources of different emission colors, and also the light guide plate due to heat from the light source even during long-time use Can be avoided.

In the light guide plate according to claim 1 of the present invention, the exit surface part and / or the non-emission surface part has an arcuate or corrugated region corresponding to the directivity characteristic of the light source from the incident end surface part corresponding to the light source as a mirror surface part. In other regions, a fine dot-shaped light deflection element is provided.

The light guide plate according to claim 1 has an arcuate or corrugated region corresponding to the directivity characteristic of the light source from the incident end surface corresponding to the light source as the mirror surface portion on the exit surface portion and / or the non-light exit surface portion and other regions. Is provided with a fine dot-shaped light deflecting element, so that the amount of emitted light can be suppressed in a region corresponding to the directivity characteristic of the light source, and a desired amount of emitted light can be emitted in other regions.

  Further, the light guide plate according to claim 2 is configured such that the thickness at the incident end surface portion is T and the maximum refraction angle when light is incident from the incident end surface portion into the light guide plate is γ from the incident end surface portion. No light deflection element is provided on the exit surface portion and / or the opposite exit surface portion during the distance up to the product value of T and T.

  The light guide plate according to claim 2 has Cot γ and T from the incident end surface portion when the thickness at the incident end surface portion is T and the maximum refraction angle when light enters the light guide plate from the incident end surface portion is γ. Since no light deflecting element is provided on the exit surface portion and / or the opposite exit surface portion during the distance up to the product value, it is possible to obtain a belt-like flat mirror surface from the incident end surface portion without emitting light from the light source. it can.

Furthermore, the planar illumination device according to claim 3 is the light guide plate of claim 1 or 2,
A light source composed of a semiconductor light emitting element having an arc-shaped directivity of emitted light ;
Light guide plate and opposite to than the front surface of at least the light source has a diffuser portion at a position closer to the incident end face, and a reflector extending in the emission face direction and anti-emitting surface direction so as to cover the entrance end face,
A case for storing the light source, the light guide plate, and the reflector ;
A reflector is provided from the outside of the light guide plate, and then the light source is provided from the outside of the reflector. The reflector is provided with an opening that is substantially equal to the size of the light emitting surface of the light source. The light source is inserted into the opening and the light source and the light guide plate are incident. It is characterized by not contacting the end face .

The flat illumination device according to claim 3 is the light guide plate of claim 1 or 2,
A light source composed of a semiconductor light emitting element having an arc-shaped directivity of emitted light ;
Light guide plate and opposite to than the front surface of at least the light source has a diffuser portion at a position closer to the incident end face, and a reflector extending in the emission face direction and anti-emitting surface direction so as to cover the entrance end face,
A case for storing the light source, the light guide plate, and the reflector ;
A reflector is provided from the outside of the light guide plate, and then the light source is provided from the outside of the reflector. The reflector is provided with an opening that is substantially equal to the size of the light emitting surface of the light source. The light source is inserted into the opening and the light source and the light guide plate are incident. Since the end face portion is not in contact , the light in the lateral direction is diffused from the light source, the light returned from the light guide plate can be reflected and returned to the light guide plate, and contact between the light source and the light guide plate can be avoided. Can do.
Further, the light guide plate can be sandwiched by the reflector.

  According to a fourth aspect of the present invention, there is provided the flat illumination device according to the fourth aspect, wherein the reflector emits light when the thickness at the incident end face is T and the maximum refraction angle when light enters the light guide plate from the incident end face is γ. It extends to the distance up to the product value of Cotγ and T in the surface direction and extends to the distance up to the product value in the direction of the anti-light emitting surface or extends to the entire anti-light emitting surface.

  According to a fourth aspect of the present invention, there is provided the flat illumination device according to the present invention, wherein the reflector has a thickness T at the incident end face portion and a maximum refraction angle when light enters the light guide plate from the incident end face portion as γ. Since it extends to the distance up to the product value of Cotγ and T and extends to the distance up to the product value in the direction of the counter-exiting surface or extends to the entire counter-exiting surface part, it does not affect the output light from the light guide plate The light guide plate can be sandwiched by the reflector, and the light leaked in the direction opposite to the light emitting surface can be returned to the light guide plate again.

  Furthermore, the flat illumination device according to claim 5 is characterized in that the reflector has an opening in the size of the emission surface of the light source.

  In the flat illumination device according to the fifth aspect, since the reflector has an opening in the size of the emission surface of the light source, the light emitted from the light source is emitted from the opening even if the reflector is placed on the light guide plate side of the light source. The light can be emitted in the direction of the light guide plate.

As described above, in the light guide plate according to claim 1, the exit surface portion and / or the opposite exit surface portion has an arcuate or corrugated region corresponding to the directivity characteristic of the light source from the incident end surface portion corresponding to the light source as the mirror surface portion. At the same time, a fine dot-shaped light deflecting element is provided in the other region, so that the amount of emitted light is suppressed in the region corresponding to the directivity characteristic of the light source, and the target amount of emitted light is emitted in the other region. Can do.
For this reason, there is no reflection of the light source when observed from the exit surface portion, and the exit surface portion can obtain uniform exit light and exit light mixed with light from a plurality of light sources or light sources having different emission colors.

The light guide plate according to claim 2 has Cot γ and T from the incident end surface portion when the thickness at the incident end surface portion is T and the maximum refraction angle when light enters the light guide plate from the incident end surface portion is γ. Since no light deflecting element is provided on the exit surface portion and / or the opposite exit surface portion during the distance up to the product value, it is possible to obtain a belt-like flat mirror surface from the incident end surface portion without emitting light from the light source. it can.
Therefore, the reflector can be brought into close contact with the belt-like flat mirror surface.
Further, the position of the incident end face can be easily determined, and the workability and reliability in assembling and the like can be improved.

The flat illumination device according to claim 3 is the light guide plate of claim 1 or 2,
A light source composed of a semiconductor light emitting element having an arc-shaped directivity of emitted light ;
Light guide plate and opposite to than the front surface of at least the light source has a diffuser portion at a position closer to the incident end face, and a reflector extending in the emission face direction and anti-emitting surface direction so as to cover the entrance end face,
A case for storing the light source, the light guide plate, and the reflector ;
A reflector is provided from the outside of the light guide plate, and a light source is provided from the outside of the reflector in that order. The reflector is provided with an opening that is substantially equal to the size of the light exit surface. Since the end face portion is not in contact , the light in the lateral direction is diffused from the light source, the light returned from the light guide plate can be reflected and returned to the light guide plate, and contact between the light source and the light guide plate can be avoided. Can do.
Further, the light guide plate can be sandwiched by the reflector.
Therefore, it is possible to avoid abnormal emission light due to contact between the light source and the light guide plate and non-mixed emission light due to light sources of different emission colors, especially mixing light from light sources of different emission colors Can do.
Further, light leaking from the light guide plate can be eliminated.
Furthermore, it is possible to avoid deformation of the light guide plate due to heat from the light source even when used for a long time.

According to a fourth aspect of the present invention, there is provided the flat illumination device according to the present invention, wherein the reflector has a thickness T at the incident end face portion and a maximum refraction angle when light enters the light guide plate from the incident end face portion as γ. Since it extends to the distance up to the product value of Cotγ and T and extends to the distance up to the product value in the direction of the counter-exiting surface or extends to the entire counter-exiting surface part, it does not affect the output light from the light guide plate The light guide plate can be sandwiched by the reflector, and the light leaked in the direction opposite to the light emitting surface can be returned to the light guide plate again.
Therefore, it can be provided in close contact with the light guide plate, light can be used effectively, and bright outgoing light can be obtained.

In the flat illumination device according to the fifth aspect, since the reflector has an opening in the size of the emission surface of the light source, the light emitted from the light source is emitted from the opening even if the reflector is placed on the light guide plate side of the light source. The light can be emitted in the direction of the light guide plate.
Therefore, the light emitted from the light source can be emitted to the incident end surface portion of the light guide plate without contacting the light source and the light guide plate, and the leaked light from the incident end surface portion can be returned to the light guide plate again.
Further, light leaking from the light guide plate can be eliminated.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
1 is a schematic cross-sectional view of a flat illumination device including a light guide plate according to the present invention, FIG. 2 is a schematic front view of the light guide plate according to the present invention, and FIG. 3 is a schematic perspective view and a cross-sectional view of the reflector according to the present invention. is there.
In addition, this invention provides the following light guide plates and planar illuminating devices. That is, the remainder of the product of the maximum refraction angle γ and the thickness of the incident end face when the light enters the incident end face in the opposite direction from the incident end face to the exit face and the opposite exit face of the light guide plate. The region between the distances up to the value of the tangent function is the mirror surface portion, the region corresponding to the directivity characteristics of the light source is the mirror surface portion, and the light guide plate provided with the light deflection element in the other region, and the light exit surface of the light source A reflector having an opening in size and having a diffusing portion, extending to the mirror surface portion of the exit surface portion of the light guide plate, and similarly extending to the mirror surface portion of the anti-light exit surface portion or extending to the entire anti-exit surface portion; A flat illumination device composed of a light source having directional characteristics, wherein the amount of emitted light is suppressed in a region corresponding to the directional characteristic of the light source in the light guide plate, and a desired amount of emitted light in other regions. The light source is reflected when observed from the exit surface. No.
Further, in the reflector, an opening is provided in the size of the light exit surface of the light source at a position opposite to the light source so that a diffuser is provided at a position closer to the incident end face than the surface of the light source in both ends of the light source. Therefore, it is possible to diffuse the light in the lateral direction from the light source, reflect the light returned from the light guide plate, and return it to the light guide plate again, while avoiding contact between the light source and the light guide plate, and abnormal outgoing light due to contact In addition, it is possible to avoid unmixed outgoing light from a plurality of light sources of different emission colors, and to avoid deformation of the light guide plate due to heat from the light source even during long-time use, and as a whole outgoing surface part Uniform outgoing light and mixed outgoing light can be obtained even with light from a plurality of light sources and light sources having different emission colors.
Furthermore, it is possible to provide a mirror surface portion up to the shortest exit position on the incident end face portion of the outgoing light depending on the thickness of the incident end face portion, and to sandwich the light guide plate with the reflector, thereby eliminating leakage light from the light guide plate.

  As shown in FIG. 1, the flat illumination device 1 is placed so that a light source 16 on which a semiconductor light emitting element 17 is placed on a substrate or the like is housed in an opening 14 provided in a vertical surface 13 of a reflector 11. The light guide plate 2 is provided on the emission side 13a of the vertical surface 13 of the reflector 11, and the light source 16, the reflector 11, the light guide plate 2 and the like are housed.

  The light guide plate 2 is formed of a transparent acrylic resin (PMMA) having a refractive index of about 1.4 to 1.7, polycarbonate (PC), etc., and is disposed on the opposite side of the incident end surface portion 3 and the incident end surface portion 3 for guiding light. The anti-incidence end face part 3b located, the outgoing face part 5 that emits the guided light, the opposite outgoing face part 6 located on the opposite side of the outgoing face part 5, and the side face connected to the outgoing face part 5 and the opposite outgoing face part 6 Part 4.

The light incident on the light guide plate 2 travels into the light guide plate 2 in a range where the refractive index γ satisfies the expression 0 ≦ | γ | ≦ Sin ⁻¹ (1 / n). For example, since the refractive index of acrylic resin, which is a resin material used for the general light guide plate 2, is about n = 1.49, the maximum incident angle is from the direction of the exit surface portion 5 of the entrance end surface portion 3 to the opposite exit surface portion 6. The light in the direction and the light from the opposite exit surface portion 6 direction to the exit surface portion 5 direction has an incident angle of 90 °, and the refraction angle γ refracted by the incident end surface portion 3 is in the range of γ = 0 to ± 42 °.
However, in the vicinity of the exit surface portion 5, only γ = −42 ° in the direction of the exit surface portion 6 only, and in the vicinity of the exit surface portion 6, only γ = + 42 ° in the direction of the exit surface portion 5 only.

  Further, the light incident on the light guide plate 2 within the range of the refraction angle γ = 0 to ± 42 ° is Sin α = (1 / n) at the boundary surface between the light guide plate 2 and the air layer (n = 1). The critical angle can be expressed by an equation. For example, since the refractive index of acrylic resin, which is a resin material used for the general light guide plate 2, is about n = 1.49, the critical angle α is about α = 42 °. If the exit surface portion 5 and the opposite exit surface portion 6 of the light guide plate 2 have no projections or depressions for deflecting light rays or do not exceed the critical angle α, the light in the light guide plate 2 is emitted from the exit surface portion 5 or the opposite exit surface portion 6. Thus, the light travels in the direction of the anti-incident end face 3b while totally reflecting.

In addition, the light guide plate 2 is formed as a mirror surface portion 7 from the incident end surface portion 3 of the exit surface portion 5 or the opposite exit surface portion 6 to an arbitrary distance in the direction of the anti-incident end surface portion 3b.
The width of the mirror surface portion 7 (an arbitrary distance from the incident end surface portion 3 toward the non-incident end surface portion 3b) depends on the thickness T at the incident end surface portion 3 of the light guide plate 2 and is the shortest from the incident end surface portion 3. The total reflected light travels in the direction of the exit surface portion 5 and the counter-exit surface portion 6 at a distance. When light enters the light guide plate 2 from the incident end surface portion 3, the maximum refraction angle γ is γ = The light having an angle of ± 42 ° and directed toward the exit surface portion 5 has an incident angle of 48 ° with respect to the exit surface portion 5. The reflected light is advanced in 6 directions.

Similarly, the light directed toward the counter-exit surface 6 has an incident angle of 48 ° with respect to the counter-exit surface 6, and if it is a mirror surface, is totally reflected and advances the reflected light toward the output surface 5.
For this reason, since there is no total reflected light between the thickness T at the incident end face 3 and the maximum refraction angle γ between the incident end face 3 and the product of Cot γ and T, this outgoing face portion 5 and the non-emission surface portion 6 are provided with a mirror surface portion 7 without providing the light deflection element 9 or the like.

Further, the light guide plate 2 has an incident end surface at a position corresponding to the semiconductor light emitting element 17 of the light source 16 placed in the vicinity of the incident end surface portion 3 in the direction from the incident end surface portion 3 of the exit surface portion 5 or the opposite exit surface portion 6 to the anti-incident end surface portion 3b. A region 8 corresponding to the directivity characteristic of the light source 16 from the portion 3 toward the non-incident end face portion 3b is a mirror surface.
The size and area shape of the mirror surface area 8 is a light shape projected from the semiconductor light emitting element 17 and the light source 16 onto the incident end face portion 3 of the light guide plate 2 and has an arc shape as shown in FIGS. The width, curvature, and the like vary depending on the directivity characteristics of the emitted light, and the region 8 corresponding to the directivity characteristics is used as the mirror surface area 8 in any case.

  Further, the light guide plate 2 is provided with a light deflection element 9 in the region other than the mirror surface region 8 and the mirror surface portion 7 on the light exit surface portion 5 and the counter light exit surface portion 6 so as to break the reflected light or critical angle close to the critical angle. The light can be refracted and emitted from these portions.

  Thus, as can be seen from the above description, the light exited from the mirror surface portion 7 in the direction opposite to the incident surface portion 3b and the light exiting surface portion 6 are totally reflected by the opposite surfaces. If the light deflection element 9 or the like is provided in the direction opposite to the incident surface 3b from the mirror surface 7, the critical angle is broken and light is emitted to the outside. For this reason, when the region 8 at a position corresponding to the directional emission region such as the semiconductor light emitting element 17 having a strong directivity is made into a mirror surface, there is no reflection of the light source when observed from the emission surface 5 and the required emission surface 5 As a whole, uniform outgoing light can be obtained.

  Further, the reflector 11 can be brought into close contact with the belt-like flat mirror surface portion 7 and the position of the incident end surface portion 3 can be easily determined, thereby improving workability and reliability in assembling and the like. it can.

  The light source 16 may be a semiconductor light emitting element 17 mounted directly on a substrate or the like, or may be injection or transfer mold, etc. A lead made of a phosphor bronze material or the like in which a pattern is formed in a resin by insert molding The semiconductor light emitting element 17 may be formed by die bonding or wire bonding after the frame is inserted and formed on the lead frame by molding resin.

The resin to be formed is made of an insulating material such as a modified polyamide, prebutylene terephthalate, nylon 46, or an aromatic polyester, and is made of titanium in order to improve light reflectivity and obtain light shielding properties. A mixture in which white powder such as barium acid is mixed is heated and injection molded.
In addition, in the mold for heat injection molding, a portion corresponding to the periphery of the emission direction is processed with fine irregularities.

The semiconductor light-emitting element 17 is a high-intensity light-emitting element composed of a semiconductor chip of a compound such as a quaternary compound or an InGaAlP-based, InGaAlN-based, or InGaN-based compound. R (red light emission) G (green light emission) B (blue) Light emission) or single-color semiconductor light emitting elements 17 are arranged.
Also, blue light is emitted from the blue light emitting semiconductor light emitting element 17 itself using the blue light emitting semiconductor light emitting element 17 and a fluorescent material which is a yellow light emitting wavelength conversion material. It may be a pseudo white light that is excited to emit white light by mixing yellow light emitted from a yellow light emitting fluorescent material with a blue light emission color.
Here, electrode terminals, connection lead wires, wirings, and the like of the light source 16 are omitted and not shown.

  As shown in FIG. 3, the reflector 11 includes an upper surface 12 having a narrow width upward, a lower surface 15 positioned on the opposite side, and a vertical surface 13 connecting the upper surface 12 and the lower surface 15. Further, the vertical surface 13 has a side facing the incident end surface part 3 of the light guide plate 2 as an emission side 13a and the opposite side as a counter-emission side 13b, and the vertical surface 13 is a position where the semiconductor light emitting element 17 of the light source 16 is placed. An opening 14 is provided at a position corresponding to.

Further, the reflector 11 is formed of a thermoplastic resin such as acrylic resin (PMMA) or polycarbonate (PC), and a white material such as titanium oxide is mixed in the diffusion portion to increase reflection efficiency or to scatter and reflect. Fine irregularities have been processed.
Note that the diffusing portions are the light guide plate 2 side, 15 and 13a in FIG. 3 facing the light guide plate 2 (outgoing surface portion 5, counter-emitting surface portion 6 and incident end surface portion 3).

Further, the light in the lateral direction can be diffused from the emission surface portion of the light source 16 and the semiconductor light emitting element 17 by the diffusion portion particularly at a position close to the incident end surface portion 3.
Furthermore, the light returned from the light guide plate 2 (anti-incident end surface portion 3b) can be reflected by the diffusing portion and returned to the light guide plate 2 again.
Furthermore, abnormal outgoing light due to contact between the light source 16 or the semiconductor light emitting element 17 and the light guide plate 2 or unmixed outgoing light due to the light source 16 or the semiconductor light emitting element 17 having a plurality of different emission colors can be avoided. Light from the light sources 16 and the semiconductor light emitting elements 17 having a plurality of different emission colors can be mixed.

The opening 14 has the same size as the exit surface of the light source 16 and the exit surface of the semiconductor light emitting element 17, and a small gap is provided on the light guide plate 2 side so that a part can be inserted. The contact between the light emission surface 17 and the incident end surface portion 3 of the light guide plate 2 is avoided.
Furthermore, the deformation of the light guide plate 2 due to heat from the light source 16 can be avoided even when used for a long time.

Further, the reflector 11 covers the output surface portion 5 and the anti-output surface portion 6 in a width corresponding to the mirror surface portion 7 from the incident end surface portion 3 of the light guide plate 2, and the light guide plate 2 is covered with the reflector 11 without affecting the light emitted from the light guide plate 2. Be able to pinch.
Incidentally, this is because, in the light guide plate 2, when the thickness at the incident end surface portion 3 is T and the maximum refraction angle when light enters the light guide plate 2 from the incident end surface portion 3 is γ, the incident end surface is as follows. It is equal to the distance from the part 3 to the product value of Cotγ and T.

  Furthermore, since the reflector 11 extends over the entire anti-light-emitting surface portion 6 of the light guide plate 2, the light leaked in the direction of the anti-light-emitting surface portion 6 can be returned to the light guide plate 2 again.

  The case 18 is formed from a resin in which a white material such as titanium oxide is mixed into a thermoplastic resin having strength, a plastic resin such as a thermoplastic resin, or a metal such as an aluminum die-cast, and the light guide plate 2 or the light source 16. In addition, the reflector 11 and the like are accommodated, and in some cases, a diffuser (not shown) is placed on the upper portion (on the light guide plate 2).

  Although not shown here, the diffuser is made of transparent acrylic resin (PMMA), polycarbonate (PC), etc., and has fine irregularities on the front and back surfaces, and one light beam passes through the diffuser. It is possible to diffuse in a random direction and make a strong luminance part, a dark part, etc. inconspicuous.

As described above, according to the present invention, when the directional light from the directional light source is guided into the light guide plate, the exit surface and the anti-emission of the light guide plate facing the position of the light source provided near the incident end surface portion of the light guide plate. The amount of emitted light in the region corresponding to the directional characteristics of the light source can be made to be a mirror surface with respect to the surface from the incident end face portion to the arc-shaped or corrugated region having a strong light intensity that matches the directional characteristics of the light source. In other areas, a desired amount of emitted light can be emitted. As a result, there is no reflection of the light source when observed from the exit surface portion, and the exit surface portion can obtain uniform exit light and exit light mixed with light from a plurality of light sources or light sources having different emission colors. A light guide plate can be provided. Further, when the light having the maximum refraction due to incidence from the incident end face portion proceeds in the direction of the exit surface or the counter exit surface, particularly the thickness of the incident end face portion among the thickness of the light guide plate, the distance from the entrance end face portion is The value is a cotangent function of the product of the maximum refraction angle γ upon incidence and the thickness of the incident end face. For this reason, since there is no light beam that is totally reflected from the incident end surface portion to this value, the region between the distance to the incident end surface portion depending on the thickness of the light guide plate is defined as a mirror surface portion, and these flat mirror surfaces The light guide plate can be sandwiched between the reflectors using the portion, the deviation between the light guide plate and the reflector can be eliminated, and the reflector can be brought into close contact with the light guide plate. In addition, it is possible to provide a light guide plate that can easily determine the position of the incident end face portion and can improve workability and reliability in assembly and the like.
In addition, the reflector is provided with a plurality of openings that are substantially equal to the size of the light exit surface, and the reflector diffuser is placed closer to the entrance end face of the light guide plate than the surface of the light source. It can eliminate light, diffuse lateral light from the light source, reflect light returning from the light guide plate, return it to the inside of the light guide plate, and avoid contact between the light source and the light guide plate. A reflector that can avoid deformation of the light guide plate due to heat from the light source even during time use. The light guide plate and the reflector cause abnormal outgoing light or multiple different light emission due to contact between the light source and the light guide plate. It is possible to provide a flat illumination device capable of avoiding unmixed outgoing light due to color light sources, and particularly capable of mixing light from light sources having a plurality of different emission colors.

It is a schematic sectional drawing of the plane illuminating device containing the light-guide plate which concerns on this invention. It is a schematic front view of the light-guide plate which concerns on this invention. It is the approximate group perspective view and sectional drawing of the reflector which concern on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Planar illumination apparatus 2 Light-guide plate 3 Incident end surface part 3b Anti-incident end surface part 4 Side surface part 5 Outgoing surface part 6 Anti-emission surface part 7 Mirror surface part 8 Mirror surface area 9 Light deflection element 11 Reflector 12 Upper surface 13 Vertical surface 13a Outgoing side 13b Non-emission side 14 Opening portion 15 Lower surface 16 Light source 17 Semiconductor light emitting element 18 Case T Thickness of light guide plate (thickness of incident end surface portion)
γ refraction angle (maximum refraction angle)
n Refractive index α Critical angle

Claims (5)

An incident end surface portion that guides light from a light source composed of a semiconductor light emitting element having emitted light having an arc-shaped directivity , an exit surface portion that emits the guided light, and a counter-exit surface portion located on the opposite side of the exit surface portion In the light guide plate composed of the side surface portion to which the emission surface portion and the opposite emission surface portion are connected,
The exit surface portion and / or the counter-exit surface portion has an arcuate or corrugated region corresponding to the directivity characteristic of the light source from the incident end surface portion corresponding to the light source as a mirror surface portion, and the other regions have fine details. A light guide plate comprising a dot-shaped light deflection element. When the thickness at the incident end face portion is T and the maximum refraction angle when light enters the light guide plate from the incident end face portion is γ, the light guide plate has Cot γ and T from the incident end face portion. 2. The light guide plate according to claim 1, wherein the light deflection element is not provided on the exit surface portion and / or the opposite exit surface portion during a distance up to a product value of. The light guide plate according to claim 1 or 2,
A light source composed of a semiconductor light emitting element having an arc-shaped directivity of emitted light ;
It has a diffusion portion at a position closer to the entrance end surface than the front surface of at least the light source to face the light guide plate, the emission surface direction and the extending anti emitting surface direction so as to cover said entrance end face A reflector to
A case for storing the light source, the light guide plate, and the reflector is provided ,
The reflector is provided from the outside of the light guide plate, and the light source is provided in order of the light source from the outside of the reflector. The reflector is provided with an opening that is substantially equal to the size of the emission surface of the light source, and the light source portion is inserted into the opening. In addition , the flat illumination device is characterized in that the light source and the incident end surface portion of the light guide plate are not in contact with each other . The reflector has Cot γ and T in the direction of the exit surface when T is the thickness at the entrance end surface and γ is the maximum refraction angle when light enters the light guide plate from the entrance end surface. 4. The flat illumination device according to claim 3, wherein the flat illumination device extends to a distance up to a product value and extends to a distance up to the product value in the direction of the counter-exiting surface or to the entire counter-exiting surface. . The flat illumination device according to claim 3, wherein the reflector has an opening in a size of an emission surface of the light source.

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