JP4634264B2 - Light guide plate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a light guide plate used for illuminating a panel such as a liquid crystal display device, a fluorescent display tube, or a display panel from the back, and a method for manufacturing the same.

  Conventionally, when a light beam of a point light source is incident on the light guide plate from one side of the light guide plate, it is easy to directly irradiate the light beam from the light source to a location located in front of the light source in the light guide plate. However, it is difficult for the light beam from the light source to be irradiated to the part deviating from the light beam other than the front surface. Therefore, for example, in the light guide plate disclosed in Patent Document 1, a plurality of grooves for guiding light rays from the light source in a predetermined direction are formed on the lower surface thereof. That is, in the light guide plate 51 of Patent Document 1, as shown in FIG. 11, the groove 53 is formed so as to meander greatly toward the light source 52. More specifically, the groove closer to the light source 52 among the plurality of grooves 53 is configured to meander at a large acute angle with respect to the central axis X of the light source 52. A part of the light beam emitted from the light source 52 is reflected by a groove adjacent to the light source 52, that is, a large meandering groove, and spreads in the left-right direction. The spread of the light beam is proportional to the size of the meandering of the groove. That is, the light beam reflected by the groove having a larger meandering spreads more in the left-right direction. As a result, conventionally, it is difficult for light from the light source to be directly irradiated on the light guide plate, and it is possible to irradiate the light emitted from the light source even at a predetermined portion other than the front surface of the light source.

Further, in the light guide plate disclosed in Patent Document 2, a plurality of holes are provided at a location facing the light source (light incident portion), that is, a location positioned in front of the light source. The insides of the plurality of holes are filled with air. A part of the light beam emitted from the light source is introduced into the light guide plate through the light incident part, and then reflected or refracted at the interface between the air and the light guide plate filled in each hole. While passing through the air. As a result, the light introduced into the light guide plate is diffused by the air filled in the holes, the light distribution in the light guide plate is widened, and the light is also emitted from the light source at a predetermined location other than the front surface of the light source. It is possible to irradiate light rays. In this case, the holes filled with air function as light distribution adjusting means for adjusting the light distribution in the light guide plate. Further, in Patent Document 2, as similar light distribution adjusting means, a plurality of diffusion materials made of, for example, barium sulfate having a refractive index different from that of the light guide plate, a plurality of bubbles, a glass beads having a refractive index different from that of the light guide plate, etc. A light guide plate having such a fine particle in a light incident portion is disclosed.
JP 2002-8423 A JP 2002-175713 A

  In the above conventional light guide plate, it is possible to irradiate the light beam emitted from the light source at a predetermined site other than the front surface of the light source, regardless of the configuration in which the light beam of the light source is incident from one side surface. The formation of dark parts is suppressed as much as possible. However, since a part of the light beam emitted from the light source is reflected toward a predetermined part other than the front surface of the light source, the amount of the light beam radiated to a position located in front of the light source is inevitably reduced. Resulting in. In this case, there is a high possibility that the brightness of the portion of the light guide plate located in front of the light source, that is, the central portion of the light guide plate cannot be obtained sufficiently. As a result, the luminance may decrease over the entire light guide plate. Alternatively, luminance unevenness may occur due to a decrease in the brightness of the central portion of the light guide plate, and uniform light emission may be difficult as a whole.

  The present invention has been made in view of such conventional circumstances, and an object of the present invention is to provide a light guide plate and a method for manufacturing the same that can improve luminance and can uniformly emit light as a whole.

In order to achieve the above object, the invention according to claim 1 is an incident end face for allowing a light beam from a light source to enter the inside, and a light beam incident from the incident end face formed by cutting a plurality of grooves. A light guide plate that includes a reflecting portion that reflects light in a predetermined direction, and an emitting portion that emits light reflected by the reflecting portion to the outside, and a plurality of the incident end faces are provided. in the vicinity of the deep grooves than the depth of grooves in the first reflecting section for reflecting the light rays incident from a light incident end face, our Keru the first reflecting on the second reflecting part for reflecting the light rays incident from the other incident end face exists as a groove which is continuous with part of the groove, the first reflecting portion is formed on the front side of the light source in the longitudinal direction of the groove, the second reflecting portion in the longitudinal direction of the groove Of the first reflecting portion And summarized in that formed on the side.

  According to the above configuration, the light guide plate is provided with a plurality of incident end faces, and light from the light source enters the light guide plate through each incident end face. In this case, in the vicinity of one incident end face, the first light reflecting portion that reflects the light incident from the incident end face is efficiently reflected toward the emitting portion. On the other hand, in the vicinity of one incident end face, the light incident from the other incident end face is reflected with respect to the second reflecting portion to which the light incident from the incident end face does not sufficiently reach. That is, for the second reflecting portion where the light beam incident from one incident end surface does not reach sufficiently, the light beam incident from the one incident end surface is not distributed but the light beam incident from the other incident end surface is distributed. It is reflected. Therefore, according to the light guide plate of the present invention, by providing a plurality of incident end faces that allow the light from the light source to enter, the light guide plate having only one incident end face (the light guide plate that allows the light from the light source to enter from one side) is provided. Thus, it is not necessary to distribute the light beam incident from the incident end face, and as a result, the possibility that the brightness at the exit portion of the light guide plate is lowered is low.

  However, it is unavoidable that the second reflecting portion in the vicinity of the one incident end face is irradiated with a light ray incident from another incident end face, so that a difference in the amount and intensity of the irradiated light ray is avoided. Absent. In such a case, in the vicinity of one incident end face, the first reflecting portion and the second reflecting portion may cause generation of luminance unevenness in the exit portion of the light guide plate.

  Therefore, in the present invention, the depth of the groove in the second reflecting portion is formed deeper than the depth of the groove in the first reflecting portion. As a result, it is possible to adjust the amount and intensity of light that enters from the other incident end face and irradiates the groove in the deeply formed second reflecting portion. That is, it is possible to make the amount and intensity of the light incident on the second reflecting portion after being incident from the other incident end face the same as the amount and intensity of the light irradiated on the first reflecting portion. Therefore, luminance unevenness at the light emitting portion of the light guide plate is suppressed, and uniform light emission can be ensured as a whole.

The gist of the invention described in claim 2 is that the light guide plate has a substantially square planar shape, and the other incident end face is provided at a position opposite to the one incident end face.
According to the above configuration, by providing at least one other incident end surface at a position opposite to the one incident end surface, the second reflecting portion to which the light incident from the one incident end surface does not reach the second reflecting portion is one. The incident light is irradiated from the end face (other incident end face) opposite to the incident end face. Thereby, it becomes easy to irradiate the same light with respect to a 2nd reflection part. That is, the amount of light irradiated to the second reflecting portion is sufficiently secured, and unevenness in luminance at the light exiting portion of the light guide plate is suitably suppressed, and it is easy to ensure uniform light emission as a whole. It becomes.

The gist of the invention described in claim 3 is that, in the second reflecting portion on the one incident end face side, a deep groove is provided as the distance from the other incident end face increases.
As described above, the light beam incident from the other incident end face is irradiated on the second reflecting portion on the one incident end face side. At this time, in the second reflecting portion of the present invention, a deep groove is provided as the distance from the other incident end face increases. For this reason, the light beam irradiated from the other incident end face side to the specific groove that is farthest from the other incident end face is not reflected by the intermediate groove and may travel to the specific groove. Becomes higher. Therefore, the amount of light reflected in a specific groove that is the farthest from the other incident end face is not reduced, and it becomes easier to ensure uniform light emission as a whole at the exit portion of the light guide plate.

The gist of the invention described in claim 4 is that the second reflecting portion is provided with a deep groove as the distance from the first reflecting portion increases.
Usually, in the second reflecting part on the one incident end face side, the light from the other incident end face side becomes difficult to be irradiated as the distance from the first reflecting part increases. Further, the light beam incident from one incident end face is more difficult to be irradiated as it is separated from the first reflecting portion. Therefore, in the present invention, in the second reflecting portion on one incident end face side, a deeper groove is provided in a portion (a portion away from the first reflecting portion) that is difficult to be irradiated with light rays from both incident end face sides. It will be. Thereby, even in such a part, it is possible to reliably reflect the light rays from both incident end faces in a predetermined direction. As a result, it becomes much easier to ensure uniform light emission as a whole at the exit portion of the light guide plate.

The invention according to claim 5 is an incident end face for making a light beam from a light source incident therein, a reflecting portion that is formed by cutting a plurality of grooves and reflects the light ray incident from the incident end face in a predetermined direction, The light guide plate is composed of an output part from which the light beam reflected by the reflection part is emitted to the outside, and the light incident from the incident end face is reflected to the end face facing the incident end face toward the incident end face. Reflecting means is provided, and in the vicinity of the incident end face, a groove deeper than the depth of the groove in the first reflecting portion that reflects the light incident from the incident end face reflects the light reflected by the reflecting means. the second was present as a groove which is continuous with the groove in our Keru the first reflecting portion on the reflection part of the first reflecting portion is formed in the front side of the light source in the longitudinal direction of the grooves, the first Reflecting portion, and summarized in that in the longitudinal direction of the groove is formed outside of the first reflector.

  According to the above configuration, the reflecting surface that reflects the light incident from the incident end surface is provided on the end surface facing the incident end surface. Thereby, the light beam incident from the incident end face is reflected to the opposite side (incident end face side) by the reflecting means, and is irradiated to the second reflecting portion. As a result, it is possible to adjust the amount and intensity of the light beam reflected by the reflecting means and applied to the groove in the deeply formed second reflecting portion. That is, it is possible to make the amount and intensity of the light beam reflected by the reflecting means and applied to the second reflection unit to be approximately the same as the amount and intensity of the light beam applied to the first reflection unit. Therefore, luminance unevenness at the light emitting portion of the light guide plate is suppressed, and uniform light emission can be ensured as a whole.

Invention of Claim 6 is a manufacturing method of the light-guide plate as described in any one of Claims 1-5, Comprising : From the said reflection part side, an optical output is less than 10W and a wavelength is 0.4 micrometer. In the following, and in the step of irradiating the laser beam having a thickness of 1.0 to 25.0 μm while scanning at a scanning speed in the range of 1 mm / second to 3000 mm / second in a direction parallel to the incident end face, The gist is to form a plurality of grooves.

  According to this, a laser beam having a light output of less than 10 W, a wavelength of 0.4 μm or less, and 1.0 to 25.0 μm and a scanning speed set in a range of 1 mm / second to 3000 mm / second is used. As a result, the light scattering property of the reflecting portion can be improved. As a result, it is possible to obtain a desired light guide plate capable of suppressing luminance unevenness and ensuring uniform light emission as a whole.

The gist of the invention described in claim 7 is that the laser beam is a CO ₂ laser beam having a wavelength of 9.0 to 11.0 μm.
According to the above configuration, by performing the grooving using CO ₂ laser light having a wavelength of 9.0Myuemu～11.0Myuemu, it is possible to improve the workability.

  The gist of the invention described in claim 8 is that the step is repeated a plurality of times. According to this, the said process is repeated several times, and the further improvement of the light scattering property in a reflection part is achieved by processing a groove | channel. As a result, it is possible to obtain a desired light guide plate that can easily ensure uniform light emission as a whole by suppressing luminance unevenness.

  According to the light guide plate and the method of manufacturing the same of the present invention, it is possible to improve luminance and to emit light uniformly as a whole.

  Hereinafter, an embodiment in which the present invention is embodied in, for example, a light guide plate of a surface light source device used in a backlight of a liquid crystal display device will be described with reference to the drawings. First, an outline of the liquid crystal display device will be described.

  As shown in FIG. 1, the liquid crystal display device 11 includes a liquid crystal panel 12 and a surface light-emitting device 13 disposed on the back surface (surface opposite to the display surface) of the liquid crystal panel 12. The surface light emitting device 13 as a backlight includes a light guide plate 14 and light sources (light emitting diodes 15) disposed adjacent to the left and right of the light guide plate 14. One light emitting diode 15 (hereinafter referred to as LED 15) is provided to face each of a pair of opposing end faces (incident end faces to be described later) of the light guide plate 14. A scattering sheet 16 is provided between the liquid crystal panel 12 and the light guide plate 14, and a reflection sheet 17 is provided on the opposite side of the liquid crystal panel 12 with the light guide plate 14 interposed therebetween. The reflection sheet 17 serves to return the light beam leaking downward from the light guide plate 14 to the inside of the light guide plate 14.

Next, the light guide plate 14 will be described.
The light guide plate 14 is formed in a long square plate shape (planar shape is a long square shape) with a highly transparent material (for example, acrylic resin). The light guide plate 14 is reflected by the pair of incident end faces 20A and 20B that allow the light rays from the LED 15 to enter the inside, the reflection portion 21 that reflects the light rays incident from the incident end surfaces 20A and 20B in a predetermined direction, and the reflection portion 21. It has an emission part 22 for emitting the emitted light to the outside (in the present embodiment, upward). The incident end faces 20A and 20B are provided on the end faces facing each other in the light guide plate 14 and facing the LEDs 15. Moreover, the reflection part 21 is provided facing the output part 22 in order to reflect the reflected light ray outside.

  As shown in FIGS. 2 and 3, the reflection portion 21 has a groove region M in which a plurality of linear grooves 23 are arranged in parallel. The groove region M is provided at a predetermined distance from each incident end face 20A, 20B. That is, between the end of the groove region M and the incident end faces 20A and 20B, a flat buffer portion K in which no groove is formed is provided. The width and size of the buffer portion K are appropriately set in consideration of the uniformity of light emission depending on the relationship with the intensity of light, the depth of the groove, and the like.

  The pitch of each groove in the groove region M is set at equal intervals. The length direction of each groove 23 (indicated by arrow R1 in FIG. 2) is parallel to the incident end face 20A (20B), and the arrangement direction of the grooves 23 (indicated by arrow R2 in FIG. 2) is the groove 23. Is orthogonal to the length direction R1. As shown in FIG. 3, the depth of the central portion of the plurality of grooves 23 is gradually formed deeper toward the center side of the light guide plate 14. Thereby, even if it leaves | separates from 20 A of incident end surfaces (20B), predetermined light ray reflection amount is securable.

  As shown in FIG. 2, in the groove region M (reflecting portion 21), a predetermined portion M1 (M2) located near each incident end face 20A (20B) is a first reflecting portion 26A (26B) and a second reflecting portion. It is divided into section 27A (27B). Hereinafter, only the configuration of the predetermined portion M1 located in the vicinity of the incident end face 20A will be described. The configuration of the predetermined place M2 located near the other incident end face 20B is the same as the predetermined place M1 located near the incident end face 20A, and is omitted. In the present embodiment, the first reflecting portion and the second reflecting portion at the predetermined location M1 in the vicinity of the incident end surface 20A are represented by 26A and 27A, respectively, and the first reflecting portion at the predetermined location M2 in the vicinity of the incident end surface 20B and The second reflecting portions are denoted by 26B and 27B, respectively.

  In the present embodiment, the “predetermined portion M1 in the vicinity of the incident end face 20A” refers to an area in the grooves 23 constituting the groove area M that cannot sufficiently reflect the light incident from the incident end face 20A (first order). 2 is a portion (a region in which luminance unevenness occurs in the length direction R1) where a groove where even a part of the reflection portion 27A is formed is formed.

  26 A of 1st reflection parts say the site | part which can reflect the light ray which injects from 20 A of incident end surfaces directly in the predetermined location M1 near 20 A of incident end surfaces. That is, the first reflecting portion 26A refers to a substantially front portion of the LED 15 facing the incident end face 20A. On the other hand, the second reflecting portion 27A refers to a portion that cannot sufficiently reflect the light incident from the incident end face 20A and can reflect the light incident from another incident end face 20B on the opposite side. Incidentally, since the LED 15 irradiates light in a substantially front direction of the front, the light beam does not reach the part other than the irradiation direction sufficiently. That is, in the light guide plate 14 of the present embodiment that uses the LED 15, the second reflecting portion 27 </ b> A that cannot sufficiently reflect the light incident from the incident end face 20 </ b> A inevitably occurs. In the light guide plate 14 of the present embodiment, the second reflecting portion 27A appears at the corner portion of the groove region M (two corners of the groove region M).

  Each groove belonging to the predetermined location M1 in the vicinity of the incident end face 20A (in this embodiment, six grooves close to the incident end face 20A) has a groove depth in the second reflecting portion 27A and a groove in the first reflecting portion 26A. It is formed deeper than the depth of. In the present specification, the “six grooves belonging to the predetermined portion M1 in the vicinity of the incident end face 20A” are referred to as a first groove 23A to a sixth groove 23F in order from the incident end face 20A. Further, in each of the first groove 23A to the sixth groove 23F, the grooves belonging to the first reflecting portion 26A are referred to as first portions A1 to F1, and the grooves belonging to the second reflecting portion 27A are referred to as second portions A2 to F2. . That is, for each of the first groove 23A to the sixth groove 23F, the depth of the second part is formed deeper than the depth of the first part.

  As shown in FIG. 4, in the second reflecting portion 27A on the incident end face 20A side, the groove is formed deeper as the distance from the opposite incident end face 20B on which the light ray received by the second reflecting section 27A enters. That is, the second portions A2 to F2 of the first groove 23A to the sixth groove 23F are formed deeper as the distance from the incident end surface 20B increases. In other words, the second portion A2 of the first groove 23A is formed deepest, and the second portion F2 of the sixth groove 23F is formed shallowest.

  The second portions A2 to F2 of the six grooves 23A to 23F belonging to the predetermined location M1 in the vicinity of the incident end face 20A are formed deeper as the distance from the first portions A1 to F1 increases. That is, of the six grooves 23A to 23F, the second portion A2 of the first groove 23A that is closest to the incident end face 20A is formed in a stepped shape through two steps as shown in FIG. ing. And 2nd site | part A2 of 23 A of 1st grooves | channels is formed deeply gradually as it leaves | separates from 1st site | part A1 (toward the direction of arrow R3). The second groove 23B adjacent to the first groove 23A also has the same shape as the first groove 23A.

  In addition, the second portion C2 of the third groove 23C among the six grooves 23A to 23F is formed in a step shape through one step as shown in FIG. 5B. The second portion C2 of the third groove 23C is gradually formed deeper as the distance from the first portion C1 increases. The fourth groove 23D adjacent to the incident end face 20B side with respect to the third groove 23C has the same shape as the third groove 23C. Furthermore, as shown in FIG. 5C, the second portion E2 of the fifth groove 23E is formed flat and has a constant depth. The sixth groove 23F adjacent to the incident end face 20B side with respect to the fifth groove 23E also has the same shape as the fifth groove 23E. Note that the second part E2 of the fifth groove 23E and the second part F2 of the sixth groove 23F are formed deeper than the first parts E1 and F1 of the grooves 23E and 23F. It is considered that it is formed deeper as it moves away from one part.

  Further, in the region M3 other than both the predetermined portion M1 located in the vicinity of the incident end surface 20A and the predetermined portion M2 located in the vicinity of the incident end surface 20B, there is a low possibility of uneven brightness, so this region M3 The grooves 23 belonging to are formed with the same depth in the length direction R1 (see FIG. 2).

Next, a method for manufacturing the light guide plate 14 will be described.
The light guide plate 14 is obtained by scanning a laser beam in parallel with the incident end face 20A (20B) on the back surface of a resin transparent substrate to form a predetermined number of grooves. As the constituent resin of the transparent substrate used here, an acrylic resin, an ester resin, an olefin resin, a vinyl resin, an epoxy resin, an ether resin, and the like are conceivable. It is not something. Among these resins, an acrylic resin is preferable from the viewpoint of being particularly excellent in transparency and workability.

  In addition, as the transparent substrate, a substrate manufactured by a cell casting method, an extrusion method, or the like is known, and among these, it is possible to process a groove having high light diffusibility when performing laser processing. From such a viewpoint, it is preferable to use a substrate manufactured by a cell casting method.

  In the laser processing, the light output of the laser light is preferably less than 10W. When this light output is 10 W or more, there is a high possibility that the light scattering property of the reflecting portion 21 is lowered. As a result, it is difficult to ensure uniform light emission as a whole at the light emitting portion 22 of the light guide plate 14.

The wavelength range of the laser light is preferably 0.4 μm or less and in the range of 1.0 μm to 25.0 μm. When the wavelength is more than 0.4 μm to less than 1.0 μm and more than 25.0 μm, the absorption due to the electronic transition absorption of the substrate material or the stretching vibration and bending vibration of the chemical bond becomes small, and the transparent substrate There is a high possibility that it is difficult to process a groove having a desired depth. The type of laser light to be used is not particularly limited as long as it is laser light that oscillates within a wavelength range of 0.4 μm or less and 1.0 μm to 25.0 μm. Examples of this type of laser light include laser light that oscillates infrared light and laser light that oscillates ultraviolet light. Examples of laser light that oscillates infrared light include CO ₂ laser light, CO laser light, YAG laser light, YVO ₄ laser light, and semiconductor laser light. Examples of laser light that oscillates ultraviolet rays include third harmonic, fourth harmonic, and excimer laser light of YAG laser light and YVO ₄ laser light. Among these, the viewpoint that it is oscillated in a wavelength range (9.0 μm to 11.0 μm) in which the absorption coefficient of the transparent substrate becomes large to improve workability in groove processing on the transparent substrate, and is small and low cost. Therefore, it is preferable to use CO ₂ laser light.

  Furthermore, the scanning speed of the laser beam is preferably in the range of 1 mm / second to 3000 mm / second. More preferably, it is in the range of 100 mm / second to 2000 mm / second. When this scanning speed is less than 1 mm / second, there is a problem that the processing time becomes very long. On the other hand, when the scanning speed exceeds 3000 mm / second, the grooves 23 are hardly formed stably, and it becomes difficult to ensure uniform light emission as a whole at the emission portion 22 of the light guide plate 14. In the present embodiment, from the viewpoint of improving the light scattering property of the groove 23, it is preferable to repeat the laser processing under the predetermined processing conditions a plurality of times.

  Now, when the light guide plate 14 of the present embodiment is employed in the surface light emitting device 13, for example, the light beam of the LED 15 is incident on the inside of the light guide plate 14 through a pair of opposite incident end surfaces 20A and 20B. In this case, for example, in the predetermined portion M1 in the vicinity of the incident end face 20A, regarding the first reflecting portion 26A that reflects the light incident from the incident end face 20A, the same light is efficiently reflected toward the emitting section 22 side. The On the other hand, in the predetermined portion M1, the light incident from the incident end face 20A is reflected by the second reflecting portion 27A which is very unlikely to be reflected without sufficiently reaching the incident end face 20A. Will be. That is, the light beam incident from the incident end surface 20A is not reflected, but the light beam incident from the incident end surface 20B is reflected instead of the light beam incident from the incident end surface 20A. ing. Therefore, in the present embodiment, the problem that the amount and intensity of light incident from the incident end face 20A is reduced is avoided, and sufficient brightness at the center portion of the light guide plate 14 is secured.

  At this time, the second reflecting portion 27A on the incident end face 20A side is irradiated with the light ray incident from the opposite incident end face 20B, so that there is a difference in the amount and intensity of the irradiated light ray. Is inevitable. In such a case, in the predetermined location M1 in the vicinity of the incident end face 20A, the first reflective portion 26A and the second reflective portion 27A may cause luminance unevenness in the light emitting portion 22 of the light guide plate 14.

  Therefore, in the present embodiment, with respect to each of the grooves 23A to 23F located at the predetermined location M1 in the vicinity of the incident end face 20A, the depth of the second portion belonging to the second reflecting portion 27A is set to the first depth belonging to the first reflecting portion 26A. It is formed deeper than the depth of one part. Accordingly, it is possible to adjust the amount and intensity of light that enters from the incident end face 20B and is irradiated to the second part formed deeper than the first part in each of the grooves 23A to 23F. That is, the amount and intensity of light incident from the incident end face 20B and applied to the second reflecting portion 27A are approximately the same as the amount and intensity of light incident from the incident end face 20A and applied to the first reflecting portion 26A. It becomes possible to do.

  In addition, also at the predetermined location M2 in the vicinity of the incident end face 20B, the light incident from the incident end face 20B is efficiently reflected by the first reflecting section 26B, and is incident from the incident end face 20A and irradiated to the second reflecting section 27B. The amount and intensity of the received light become approximately the same as the amount and intensity of the light incident from the incident end face 20B and applied to the first reflecting portion 26B. Thereby, sufficient light emission is ensured also about the corner part of the light-guide plate 14 like a center part. As a result, luminance unevenness in the emission part 22 of the light guide plate 14 is suppressed, and uniform light emission can be ensured as a whole.

The effects exhibited by the above embodiment will be described below.
(1) For the second reflecting portion 27A to which the light incident from the incident end face 20A does not sufficiently reach, the light incident from the incident end face 20A is not distributed, but the light incident from another incident end face 20B. Is reflected. Therefore, in the present embodiment, the problem that the amount and intensity of light incident from the incident end face 20A is reduced is avoided, and sufficient brightness at the center portion of the light guide plate 14 is secured.

  (2) The grooves 23A to 23F located at the predetermined location M1 (M2) in the vicinity of the incident end face 20A (20B) are such that the depth of the second portion belonging to the second reflecting portion 27A (27B) is the first reflecting portion. It is formed deeper than the depth of the first part belonging to 26A (26B). As a result, the amount and intensity of the light incident from the other incident end face and applied to the second part formed deeper than the first part in each of the grooves 23A to 23F are incident from the one incident end face to be the first. It becomes possible to make it comparable to the amount and intensity of the light rays irradiated to the part. Accordingly, sufficient light emission is ensured at the corner portion of the light guide plate 14 as well as the central portion. As a result, luminance unevenness in the light emitting portion 22 of the light guide plate 14 is suppressed, and uniform light emission can be ensured as a whole.

  (3) By providing the incident end faces 20A and 20B so as to face each other, it becomes easy to irradiate the light beams to the second reflecting portions 27A and 27B. That is, the amount of light irradiated to the second reflecting portions 27A and 27B is sufficiently secured, and unevenness in luminance at the emitting portion 22 of the light guide plate 14 is suitably suppressed, and uniform light emission is achieved as a whole. It can be secured easily.

  (4) In the second reflecting portion 27A (27B), the groove is formed deeper as the distance from the opposite incident end surface 20B (20A) on which the light beam received by the second reflecting portion 27A (27B) is incident is increased. That is, for example, the second portions A2 to F2 of the first groove 23A to the sixth groove 23F in the second reflecting portion 27A are formed deeper as the distance from the incident end face 20B increases. As a result, the light beam travels from the incident end surface 20B to the first groove 23A that is the farthest away, and as a result, the amount of light beam reflected by the first groove 23A is not reduced. Accordingly, it becomes easier to ensure uniform light emission as a whole at the emission portion 22 of the light guide plate 14.

  (5) A predetermined groove (for example, the second portion A2 of the first groove 23A) in the second reflecting portion 27A (27B) is formed deeper as the distance from the first reflecting portion 26A (26B) increases. As a result, it is possible to reliably reflect the light beam in a predetermined direction (upward) even in a region where it is difficult to irradiate the light beam from both the incident end faces 20A and 20B. Accordingly, it is possible to ensure more uniform light emission as a whole at the emission portion 22 of the light guide plate 14. Further, in this case, the processing can be facilitated by forming a predetermined groove (for example, the second portion A2 of the first groove 23A) in the second reflecting portion 27A (27B) in a step shape.

  (6) The depth of the central portion of the plurality of grooves 23 in the groove region M is gradually formed deeper toward the center side of the light guide plate 14. Thereby, even if it leaves | separates from 20 A of incident end surfaces (20B), predetermined light ray reflection amount is securable. That is, it is possible to ensure sufficient light emission at the central portion of the emission portion 22 of the light guide plate 14.

  (7) In the present embodiment, by forming the groove 23 using laser processing, it is not necessary to use an expensive mold or the like, and therefore the manufacturing cost can be reduced. Further, by controlling the light output and the scanning speed and performing multiple overlapping drawing, a groove having a desired depth can be realized easily and with high accuracy. In addition, with the processing of the groove pattern on the light guide plate 14, the light guide plate 14 with high positional accuracy can be cut out by laser processing, which is suitable as a processing method of the light guide plate 14.

(8) As a manufacturing method of the light guide plate 14 of the present embodiment, a CO ₂ laser beam having an optical output of less than 10 W and a wavelength of 9.0 to 11.0 μm is scanned in a range of 100 mm / second to 2000 mm / second. It is preferable to repeat the irradiation process while scanning at a speed a plurality of times. Thereby, the light scattering property in the reflecting portion 21 is improved, and the light guide plate 14 that enables uniform light emission as a whole can be obtained.

In addition, this embodiment can also be changed and embodied as follows.
-In this embodiment, although 2nd site | part A2-D2 of predetermined groove | channel 23A-23D was formed in step shape, the shape of the 2nd site | part A2-D2 is not limited to this. That is, the second portions A2 to D2 may be flat as shown in FIG. 6A, for example, as long as the second portions A2 to D2 become deeper as they are separated from the first portions A1 to D1, respectively. Alternatively, it may be curved as shown in FIG. FIGS. 6A and 6B show the first groove 23A among the predetermined grooves.

  In the present embodiment, six grooves 23 that have been subjected to predetermined processing so that the depth of the second part is deeper than the first part are provided, but the number of such grooves 23 is limited to this. Not. The number of the grooves 23 to be subjected to such predetermined processing is appropriately changed depending on the width of the second reflecting portion 27A (27B) in the groove region M and the interval of the grooves 23. The width of the second reflecting portion 27A (27B) is changed according to the size of the light guide plate 14, the position and height of the LED 15, the spread angle of the light beam of the LED 15, and the like.

  In addition, regarding the optimum depth and length of the second portion (A2 to F2) that can suitably exhibit the effects of the present invention, the size of the light guide plate 14, the position and height of the LED 15 are disposed, the LED 15 Since it is changed according to the spread angle of the light beam, it is not particularly limited as long as it becomes deeper than the first part.

  In the present embodiment, in the second reflecting portion 27A on the incident end surface 20A side, the groove is formed deeper as the distance from the opposite incident end surface 20B increases. However, the depth of the groove in the second reflecting portion 27A is reduced. You may set all the same. That is, the second portions (A2 to F2) of the first groove 23A to the sixth groove 23F may all be formed to the same depth.

  In the present embodiment, the pair of incident end faces 20 </ b> A and 20 </ b> B are provided to face each other, but these incident end faces may not be provided to face each other on the light guide plate 14. Further, the number of incident end faces in the light guide plate 14 is not particularly limited.

  In the present embodiment, the pair of incident end faces 20A and 20B facing each other are provided, but the light guide plate 31 having one incident end face may be adopted. That is, in this light guide plate 31, the light beam of the LED enters from one side. In this case, as shown in FIG. 7A, a reflecting means 32 for reflecting the light beam incident from the incident end face 31A is provided on the end face facing the incident end face 31A. Examples of the reflection means 32 include conventionally known metal thin films, reflection sheets, reflection printing, and the like, but are not particularly limited as long as they have light reflectivity. As a result, as indicated by the alternate long and short dash line in FIG. 7A, the light beam incident from the incident end surface 31A is reflected by the reflecting means 32 to the opposite side (incident end surface 31A side) and irradiated to the second reflecting portion 35. Become so. Further, in this case, as shown in FIG. 7B, it is preferable that the depth of the central portion of each groove 23 increases as the distance from the incident end surface 31A increases. Thereby, the light beam incident from the incident end surface 31A can be surely advanced even to the groove 23X which is the farthest from the incident end surface 31A.

  As shown in FIG. 8A, when two LEDs 15 are provided for each incident end face 20A (20B), the second reflecting portion 27A (27B) is not only the corner portion of the groove region M, It is formed also in the location corresponding between LED15. In this case, as shown in FIG. 8B, each groove 23 belonging to the predetermined location M1 (M2) in the vicinity of the incident end face 20A (20B) has a particularly deep central portion and end in the length direction. The At this time, the groove in the second reflecting portion 27A (27B) corresponding to the space between the LEDs 15 is formed deeper toward the central portion in order to suitably suppress the luminance unevenness in the emitting portion 22 of the light guide plate 14. preferable. And the shape of the groove | channel in each 2nd reflection part 27A (27B) may be a curved surface shape as shown in FIG.8 (b), and may be the step shape formed through several level | step differences.

  In the present embodiment, the light guide plate 14 having a rectangular shape in plan view is used. However, the planar shape of the light guide plate 14 is not limited to this, and may be, for example, a regular square shape, a rhombus shape, or a regular shape. In addition to a circular shape, a semicircular shape, an elliptical shape, and the like, a polygonal shape such as a triangular shape, a pentagonal shape, and a hexagonal shape may be used. In this case, the number of incident end faces on which the light rays of the LED are incident is not particularly limited.

The height position of the LED 15 with respect to the incident end face 20A (20B) is appropriately set in consideration of the uniformity of light emission, such as the intensity of light rays and the depth of grooves.
In the present embodiment, grooves 23A to 23F in which the depth of the second reflecting part (second part) is deeper than the first reflecting part (first part) are provided in the vicinity of each incident end face 20A (20B). Yes. However, even if a groove shallower than the first reflecting part (first part) is partially mixed in the second reflecting part (second part), the depth of the groove in the second reflecting part is the first reflection. This corresponds to a structure formed deeper than the depth of the groove in the portion. In this case, it is preferable that a groove in which the average value of the depth of the second reflecting part (second part) is larger than the depth of the first reflecting part (first part) is provided in the vicinity of each incident end face.

  -In this embodiment, the deep groove | channel was formed as it separated from the 1st reflection part (1st site | part) (or as it separated from the other incident end surface). However, even if shallow grooves are mixed in the middle, this corresponds to a configuration in which deep grooves are provided as they are separated from the first reflecting portion (first portion) (as they are separated from other incident end faces).

  -You may use the light-guide plate 14 of this embodiment for the purpose of providing the color rendering effect of making parts other than a character shine in various colors in a fluorescent display tube. Moreover, you may use for the display apparatus which illuminates the character or design in display panels, such as a nameplate of a taxi, and the reel of a pachinko machine from the back.

Further, the technical idea that can be grasped from the embodiment will be described below.
-The light guide plate in which the groove | channel formed in step shape via a several level | step difference in the said 2nd reflection part is provided. According to such a configuration, uniform light emission can be ensured as a whole while ensuring ease of processing.

  A surface light emitting device comprising: the light guide plate; and a light source facing an incident end surface of the light guide plate.

Next, the embodiment will be described more specifically with reference to test examples and comparative examples.
<Evaluation 1: Evaluation of brightness and luminance unevenness in light guide plate>
[Test Examples 1 to 11 and Comparative Example 1]
Here, the light guide plate was manufactured by appropriately changing the depth and shape of each groove in the second reflecting portion 27A (27B). The groove pitch in the light guide plate of each example is 0.8 mm. Then, in the state where the LED 15 facing each of the pair of incident end faces 20A and 20B was caused to emit light, the brightness and luminance unevenness of the light guide plate in each example were evaluated visually according to the following criteria. The results are shown in Table 1. Note that “brightness unevenness” in the following evaluation criteria refers to the brightness difference in the vicinity of the corner portion of the emission portion 22 of the light guide plate 14.
◎: Brightness in the central portion of the light guide plate is ensured, and no luminance unevenness is observed and uniform as a whole. ○: Brightness in the central portion of the light guide plate is ensured and almost no uneven luminance is observed. Although the brightness in the central portion of the light plate was secured, the luminance unevenness was noticeable (Test Example 1).
As shown in FIG. 9A, in the first groove 23A and the second groove 23B of Test Example 1, the depth of the portion (second portion) from the end portion to 5.0 mm in the length direction R1 is as follows. It is 37 μm, and the depth of the other part (first part) is 17 μm. In the third groove 23C and the fourth groove 23D, the depth of the portion (second portion) from the end portion to 3.3 mm in the length direction is 37 μm, and the depth of the other portion (first portion). Is 21 μm. Moreover, in the 5th groove | channel 23E and the 6th groove | channel 23F, the depth of the location (2nd site | part) to 1.7 mm in the length direction from an edge part is 37 micrometers, and other locations (1st site | part) The depth is 25 μm.
(Test Example 2)
Here, the second portions of the first groove 23A to the fourth groove 23D are formed in a stepped shape through one step. And about the 2nd site | part of the remaining 5th groove | channel 23E and the 6th groove | channel 23F, it formed flatly. Incidentally, as shown in FIG. 9B, in the first groove 23A and the second groove 23B of the test example 2, the depth from the end portion to 3.3 mm in the length direction is 67 μm, The depth of the part from 3.3 mm to 5.0 mm is 37 μm, and the depth of the other part (first part) is 17 μm. In the third groove 23C and the fourth groove 23D, the depth from the end portion to the length of 1.7 mm is 67 μm, and the depth from 1.7 mm to 3.3 mm is 37 μm. The depth of the other part (first part) is 21 μm. Furthermore, in the 5th groove | channel 23E and the 6th groove | channel 23F, the depth of the location from the edge part to 1.7 mm in a length direction is 37 micrometers, and the depth of the other place (1st site | part) is 25 micrometers. is there.
(Test Example 3)
Here, the second portions of the first groove 23A and the second groove 23B are formed in a stepped shape through one step. And about the 2nd site | part of 3rd groove | channel 23C and 4th groove | channel 23D, it formed in flat shape. Incidentally, as shown in FIG. 9 (c), in the first groove 23A and the second groove 23B of Test Example 3, the depth from the end portion to 1.7 mm in the length direction is 107 μm, The depth of the place from 1.7 mm to 3.3 mm is 67 μm, and the depth of the other place (first part) is 17 μm. In the third groove 23C and the fourth groove 23D, the depth from the end portion to 1.7 mm in the length direction is 67 μm, and the depth of the other portion (first portion) is 21 μm. The fifth groove 23E and the sixth groove 23F have the same depth along the length direction and are set to 25 μm.
(Test Example 4)
Here, the second portion of the first groove 23A and the second groove 23B is formed in a stepped manner through two steps, and the second portion of the third groove 23C and the fourth groove 23D is formed through one step. It was formed like a staircase. And about the 2nd site | part of the remaining 5th groove | channel 23E and the 6th groove | channel 23F, it formed flatly. Incidentally, as shown in FIG. 9 (d), in the first groove 23A and the second groove 23B of Test Example 4, the depth from the end portion to 1.7 mm in the length direction is 157 μm, The depth of the portion from 1.7 mm to 3.3 mm is 67 μm, the depth of the portion from 3.3 mm to 5.0 mm is 37 μm, and the depth of the other portion (first portion) is 17 μm. It is. In the third groove 23C and the fourth groove 23D, the depth from the end portion to the length of 1.7 mm is 67 μm, and the depth from 1.7 mm to 3.3 mm is 37 μm. The depth of the other part (first part) is 21 μm. Furthermore, in the 5th groove | channel 23E and the 6th groove | channel 23F, the depth of the location from the edge part to 1.7 mm in a length direction is 37 micrometers, and the depth of the other place (1st site | part) is 25 micrometers. is there.
(Test Example 5)
Here, the second portion of the first groove 23A and the second groove 23B is formed in a stepped manner through two steps, and the second portion of the third groove 23C and the fourth groove 23D is formed through one step. It was formed like a staircase. And about the 2nd site | part of the remaining 5th groove | channel 23E and the 6th groove | channel 23F, it formed flatly. Incidentally, as shown in FIG. 9 (e), in the first groove 23A and the second groove 23B of Test Example 5, the depth from the end portion to 1.7 mm in the length direction is 107 μm, The depth of the portion from 1.7 mm to 3.3 mm is 67 μm, the depth of the portion from 3.3 mm to 5.0 mm is 37 μm, and the depth of the other portion (first portion) is 17 μm. It is. In the third groove 23C and the fourth groove 23D, the depth from the end portion to the length of 1.7 mm is 67 μm, and the depth from 1.7 mm to 3.3 mm is 37 μm. The depth of the other part (first part) is 21 μm. Furthermore, in the 5th groove | channel 23E and the 6th groove | channel 23F, the depth of the location from the edge part to 1.7 mm in a length direction is 37 micrometers, and the depth of the other place (1st site | part) is 25 micrometers. is there.
(Test Example 6)
As shown in FIG. 9 (f), in the first groove 23 </ b> A and the second groove 23 </ b> B of Test Example 6, the depth of the portion (second portion) from the end portion to 5.0 mm in the length direction is 67 μm. The depth of the other part (first part) is 17 μm. In the third groove 23C and the fourth groove 23D, the depth of the portion (second portion) from the end portion to 3.3 mm in the length direction is 67 μm, and the depth of the other portion (first portion). Is 21 μm. Moreover, in the 5th groove | channel 23E and the 6th groove | channel 23F, the depth of the location (2nd site | part) from an edge part to 1.7 mm in a length direction is 67 micrometers, and other locations (1st site | part) The depth is 25 μm.
(Test Example 7)
As shown in FIG. 9 (g), in the first groove 23A and the second groove 23B of Test Example 7, the depth of the portion (second portion) from the end portion to 5.0 mm in the length direction is 107 μm. The depth of the other part (first part) is 17 μm. In the third groove 23C and the fourth groove 23D, the depth of the portion (second portion) from the end portion to 3.3 mm in the length direction is 107 μm, and the depth of the other portion (first portion). Is 21 μm. Moreover, in the 5th groove | channel 23E and the 6th groove | channel 23F, the depth of the location (2nd site | part) from an edge part to 1.7 mm in a length direction is 107 micrometers, and other locations (1st site | part) The depth is 25 μm.
(Test Example 8)
Here, as shown in FIG. 9 (h), in the first groove 23A and the second groove 23B, the depth from the end portion to 3.3 mm in the length direction is 37 μm, and the other portions The depth of is 17 μm. In the third groove 23C and the fourth groove 23D, the depth from the end portion to 1.7 mm in the length direction is 37 μm, and the depth of the other portions is 21 μm. The fifth groove 23E and the sixth groove 23F have the same depth along the length direction and are set to 25 μm.
(Test Example 9)
Here, as shown in FIG. 9 (i), in the first groove 23A and the second groove 23B, the depth from the end portion to 3.3 mm in the length direction is 67 μm, and the other portions The depth of is 17 μm. In the third groove 23C and the fourth groove 23D, the depth from the end portion to 1.7 mm in the length direction is 67 μm, and the depth of the other portions is 21 μm. The fifth groove 23E and the sixth groove 23F have the same depth along the length direction and are set to 25 μm.
(Test Example 10)
Here, as shown in FIG. 9 (j), in the first groove 23A and the second groove 23B, the depth from the end portion to 3.3 mm in the length direction is 107 μm, and the other portions The depth of is 17 μm. In the third groove 23C and the fourth groove 23D, the depth from the end portion to the length of 1.7 mm is 107 μm, and the depth of the other portions is 21 μm. The fifth groove 23E and the sixth groove 23F have the same depth along the length direction and are set to 25 μm.
(Test Example 11)
Here, as shown in FIG. 9 (k), in the first groove 23A and the second groove 23B, the depth from the end portion to 1.7 mm in the length direction is 37 μm, and the other portions The depth of is 17 μm. In the third groove 23C and the fourth groove 23D, the depth is the same along the length direction and is 21 μm. In addition, the fifth groove 23E and the sixth groove 23F have the same depth along the length direction and are set to 25 μm.
(Test Example 12)
Here, as shown in FIG. 9 (l), in the first groove 23A and the second groove 23B, the depth from the end portion to 1.7 mm in the length direction is 67 μm, and the other portions The depth of is 17 μm. In the third groove 23C and the fourth groove 23D, the depth is the same along the length direction and is 21 μm. In addition, the fifth groove 23E and the sixth groove 23F have the same depth along the length direction and are set to 25 μm.
(Test Example 13)
Here, as shown in FIG. 9 (m), in the first groove 23A and the second groove 23B, the depth from the end portion to 1.7 mm in the length direction is 107 μm, and the other portions The depth of is 17 μm. In the third groove 23C and the fourth groove 23D, the depth is the same along the length direction and is 21 μm. In addition, the fifth groove 23E and the sixth groove 23F have the same depth along the length direction and are set to 25 μm.
(Comparative Example 1)
Here, the groove region was formed only by grooves having the same depth in the length direction. That is, in each groove of the first groove 23A to the sixth groove 23F, the first part and the second part have the same depth. The plurality of grooves are formed deeper toward the center side of the light guide plate. Incidentally, regarding the light guide plate of Comparative Example 1, the depth of the first groove 23A is 17 μm, and the depth of the specific groove located at the center of the groove region is 100 μm.

In each example, since light beams are respectively incident from a pair of opposite end faces (incident end faces 20A and 20B) in the light guide plate 14, it is confirmed that the brightness at the central portion of the light guide plate 14 is sufficiently secured. It was. As shown in Table 1, in Test Examples 1 to 13, good results were obtained in which little or no luminance unevenness was observed. This is because, in Test Examples 1 to 13, since the groove in the second reflecting part is formed deeper than the groove in the first reflecting part, the amount of light irradiated to the second reflecting part from the LED on the opposite side This is considered to be due to the fact that it is possible to make the intensity equal to the amount and intensity of light directly irradiated to the first reflecting portion from the nearby LED.

  In addition, among these test examples, it was confirmed that particularly uniform luminance was obtained in the light guide plates of Test Examples 2 to 5 (see FIG. 10A). This is considered to be due to the fact that the predetermined grooves in the second reflecting portion are each formed in a stepped shape that becomes deeper as the distance from the center portion increases.

  On the other hand, the luminance unevenness was remarkable in Comparative Example 1 (see FIG. 10B). This is because, with respect to the light guide plate of Comparative Example 1, the depth of the groove in the second reflecting portion is the same as the depth of the groove in the first reflecting portion, so that it enters from the opposite LED and enters the second reflecting portion. This is considered to be caused by a difference between the amount and intensity of the irradiated light beam and the amount and intensity of the light beam incident from a nearby LED and directly applied to the first reflecting portion.

[Comparative Examples 2-3]
Here, evaluation similar to the above was performed in a state where the light beam of the LED 15 was incident on the light guide plate 14 from one side.
(Comparative Example 2)
The light guide plate of Test Example 5 was used, and an LED light beam was incident on the light guide plate from one side. As a result, luminance unevenness was confirmed at the exit portion on the incident end face side. This is considered to be caused by the fact that the light is not easily irradiated to the second reflecting portion in the vicinity of the incident end face because light is incident only on one side of the light guide plate. From the results of Comparative Example 2 and Test Example 3 above, it was proved that the light incident from the opposite incident end face was reliably irradiated to the second reflecting portion in the vicinity of the incident end face.
(Comparative Example 3)
Using the light guide plate of Comparative Example 1, the light beam of the LED was incident on the light guide plate from one side. As a result, as in Comparative Example 2, uneven brightness was clearly confirmed at the exit portion on the incident end face side.
<Evaluation 2: Evaluation of groove processing conditions>
Here, the processing conditions at the time of processing a groove using CO ₂ laser light were changed as appropriate, and the influence of such processing conditions on the brightness at the exit portion of the light guide plate was evaluated according to the following criteria. That is, it was evaluated whether or not the light guide plate has a glare when the LEDs facing the respective incident end faces are caused to emit light. The results are shown in Table 2. Note that “feeling of glare” in the following criteria indicates whether light is scattered or not by the grooves formed in the reflecting portion. That is, when the light scattering property is excellent, no glare is felt, and uniform brightness can be obtained at the exit portion.
○: No glaring sensation is observed Δ: glaring sensation is observed (processing examples 1 to 3)
Using a CO ₂ laser oscillator (Laser Marker MLG9310 SO 9100, manufactured by Keyence Corporation), CO ₂ on the back surface of an acrylic substrate (“SUMIPEX” manufactured by Sumitomo Chemical Co., Ltd.) having a size of 81 mm × 20 mm and a thickness of 2 mm in parallel with the incident end face. The light guide plate was produced by scanning the laser beam to form a total of 89 light-scattering grooves. The processing conditions (laser light output, wavelength, scanning speed) in each example are shown in Table 2.

As shown in Table 2, in Processing Example 1 and Processing Example 2, it was confirmed that no “glittering” was observed in the light guide plate, and that uniform brightness was ensured at the exit portion. This is considered to be due to the fact that a groove capable of ensuring a sufficient light scattering property can be formed by processing with a light output of less than 10 W. On the other hand, in the processing example 3, since the processing with the light output of 10 W or more is performed, it is considered that the light scattering property in the reflecting portion is lowered.
<Evaluation 3: Evaluation of Acrylic Substrate Manufacturing Method>
(Production Examples 1-2)
Here, grooving was performed on two types of acrylic substrates having different manufacturing methods under predetermined processing conditions, and the presence or absence of “glare feeling” was evaluated in the same manner as in Evaluation 2 above. The results are shown in Table 3.
(Production Example 1)
A light guide plate was produced on the back surface of the acrylic substrate manufactured by the cell casting method by scanning the CO ₂ laser light in parallel with the incident end face under the conditions of the above-described Processing Example 1 to form a light scattering groove.
(Production Example 2)
Here, the light guide plate was produced by performing the laser processing similar to the said manufacture example 1 with respect to the back surface of the acrylic substrate manufactured by the extrusion method.

As shown in Table 3, it was confirmed that the acrylic substrate manufactured by the cell casting method was more suitable for laser processing than the extrusion method. This is because, in an acrylic substrate manufactured by the cell cast method, a solvent or a monomer remains in the substrate, so that fine holes are easily formed on the groove surface processed by laser light, and the groove has excellent light diffusibility. This is presumed to be due to the ease of formation of.

Schematic which shows a liquid crystal display device. The top view which shows the light-guide plate of this embodiment. 3-3 sectional drawing in FIG. 4-4 sectional drawing in FIG. 2A is a sectional view taken along line 5a-5a in FIG. 2, FIG. 2B is a sectional view taken along line 5b-5b in FIG. 2, and FIG. 2C is a sectional view taken along line 5c-5c in FIG. (A) And (b) is sectional drawing which shows the shape of the groove | channel of another example. (A) is a top view which shows the light guide plate of another example, (b) is 7b-7b sectional drawing in Fig.7 (a). (A) is a top view which shows the light guide plate of another example, (b) is 8b-8b sectional drawing in Fig.8 (a). (A)-(m) is schematic which shows the shape of the 2nd reflective part in each test example. (A) is a photograph showing the light guide plate of Test Examples 2 to 5, and (b) is a photograph showing the light guide plate of Comparative Example 1. The top view which shows the conventional light-guide plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 14 ... Light guide plate, 15 ... LED as a light source, 20A, 20B ... Incident end face, 21 ... Reflection part, 22 ... Output part, 23 ... Groove, 26A, 26B ... 1st reflection part, 27A, 27B ... 2nd reflection part .

Claims (8)

An incident end face for allowing light rays from the light source to enter the interior, a reflection part formed by cutting a plurality of grooves and reflecting the light incident from the incident end face in a predetermined direction, and the light rays reflected by the reflection part A light guide plate composed of an emission part that is emitted to the outside,
A plurality of the incident end faces are provided, and in the vicinity of one incident end face, a groove that is deeper than the depth of the groove in the first reflecting portion that reflects light incident from one incident end face is incident from another incident end face. exists as a groove which is continuous with our Keru groove of the first reflector to the second reflector portion for reflecting light, said first reflecting portion is formed in the longitudinal direction of the groove on the front side of the light source The light guide plate , wherein the second reflection part is formed outside the first reflection part in a length direction of the groove . 2. The light guide plate according to claim 1, wherein the light guide plate has a substantially quadrangular planar shape, and the other incident end face is provided at a position facing the one incident end face. 3. The light guide plate according to claim 1, wherein a deep groove is provided in the second reflecting portion on the one incident end face side as the distance from the other incident end face increases. 4. 4. The light guide plate according to claim 1, wherein a deep groove is provided in the second reflecting part as the distance from the first reflecting part increases. 5. An incident end face for allowing light rays from the light source to enter the interior, a reflection part formed by cutting a plurality of grooves and reflecting the light incident from the incident end face in a predetermined direction, and the light rays reflected by the reflection part A light guide plate composed of an emission part that is emitted to the outside,
Reflecting means for reflecting the light beam incident from the incident end surface to the incident end surface side is provided on the end surface facing the incident end surface,
Wherein in the vicinity of the entrance end surface, deep grooves than the depth of the grooves in the first reflecting section for reflecting the light incident from the incident end face, Keru you on the second reflecting part for reflecting the reflected rays by the reflecting means and the It exists as a groove continuous with the groove of the first reflecting portion, and the first reflecting portion is formed on the front side of the light source in the length direction of the groove, and the second reflecting portion is the length of the groove. A light guide plate formed outside the first reflecting portion in the vertical direction . It is a manufacturing method of the light guide plate according to any one of claims 1 to 5 ,
From the reflection part side, laser light having an optical output of less than 10 W, a wavelength of 0.4 μm or less, and 1.0 to 25.0 μm is 1 mm / second to 3000 mm / second in a direction parallel to the incident end face. The method for manufacturing a light guide plate, wherein the plurality of grooves are formed in the reflection portion by performing irradiation while scanning at a scanning speed in a range. The light guide plate manufacturing method according to claim 6, wherein the laser light is CO ₂ laser light having a wavelength of 9.0 to 11.0 μm. 8. The method for manufacturing a light guide plate according to claim 6, wherein the step is repeated a plurality of times.