TWI234015B - Light guide plate, surface light source device and liquid crystal display device - Google Patents

Abstract

If LED is lit, light penetrates an incident surface 16D to be guided into a light guide plate 16. The guided light is successively reflected inside the inclined surface pair 16I, 16J of a projection 16K formed on entire or part of the divisions of light path folding surfaces to direct into the light guide plate 16. As light changes direction in approximately 90 DEG after two internal reflections, the total internal reflection condition is not easy to be ruined by each internal reflection. It is possible to make the bottom part between the inclined surfaces 16I and 16J shallow while getting close to the emergent surface 16B. It is also possible to break the projection 16K and the bottom part before the emergent surface 16B. The inclined surfaces 16I and 16J are deformed as curved surface, or twisted surface. The vertex angle for the projection 16K is selected within a range between 60 DEG and 120 DEG corresponding to the inclination of the emergent surface 16B of the light path folding surfaces 16C specified within a range between 10 DEG and 70 DEG.

Description

1234015 A7 V. Description of the invention] [Background of the invention] [Technical field] The present invention relates to a light guide plate, a surface light source device, and a liquid crystal display device. In particular, the present invention relates to a light guide using a curved surface of an optical path to improve efficient light input. A light plate, a surface light source device using such a light guide plate, and a liquid crystal display device using the same surface light source device for lighting a liquid crystal display panel. The present invention is applicable to, for example, a surface light source device and a light guide plate used in a liquid crystal device attached to a mobile phone. [Related Technology] It is known to illuminate a liquid crystal display panel of a liquid crystal display device by a surface light source device. Generally, a surface light source device includes a light guide plate and a primary light source that supplies primary light to the plate. In the past, for primary light sources, rod-shaped fluorescent lamps (cold-cathode tubes) have been widely used, but in recent years, point-to-local light sources using LEDs (light emitting diodes) have been gradually adopted. Lines, especially smaller liquid crystal display devices attached to mobile phones, are becoming mainstream. An example of a liquid crystal display device printed by an employee of the Intellectual Property Bureau of the Ministry of Economic Affairs and Consumer Affairs Co., Ltd. is shown in an exploded perspective view in FIG. 9 is a cross-sectional structure of a surface light source device. The paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm). 1. If you refer to the two figures, the liquid crystal display device is a liquid crystal display panel 2 illuminated by a surface light source device 3. The surface light source device 3 includes a light guide plate 6 LED (point light source) 8 and a reflection plate 5. The light guide plate 6 has a substantially wedge-shaped cross section, and an exit surface 6B is provided by a measurement surface on one side, and a back surface 6Λ is provided by a measurement surface on the other side. Moreover, the light guide plate 6-^^ is thicker, 312095 1234015 printed by the Intellectual Property Bureau of the Ministry of Economic Affairs, and printed by the company. The paper is applicable to the standard (CNS) A4 specification. See the official director 2 A7 V. Description of the invention (2) It has a shape cut at an inclination of approximately 45 degrees so that the Liantian shooting surface 6B and the test surface 6A. An optical path curved surface 6c is provided by the inclined surface. The reflecting plate 5 is composed of a white PET film, and reflects the light leaking from the back surface 6 back to the light guide plate 6 to prevent the loss of light. In addition, various reflection directions of light are generated due to random reflection, which promotes

The exit from the exit surface 6B. The LED8 is configured with one or more according to the required brightness, and constitutes a primary light source as a whole. In this example, four LEDs are arranged at equal intervals. As can be understood from the mark in FIG. 9, these LEDs 8 are arranged approximately directly below the curved surface 6C of the optical path, and supply primary light to the curved surface of the optical path through the incident surface 6D. Port Here, the incident surface 6D is a strip-shaped area provided by the edge portion of the back surface 6A, and the front end of the same edge portion meets the optical path curved surface 6C to form an edge line. If the LED 8 is turned on, the light is introduced into the light guide plate 6 through the incident surface 6D. All the incoming light rays enter the curved surface 6C of the optical path. Then, most of the internal incident light is internally reflected by the curved surface 6C of the optical path to form a direction change of about 90 degrees. The light ray 'internally reflected by the optical path curved surface 6C propagates into the light guide plate 6 in a direction from the optical path curved surface 6C to the edge. As is well known, during this process, the back surface 6a, the internal reflection of the exit surface 6B, and the reflection from the reflecting plate 5 (after leaking from the back surface 6A), etc., are gradually emitted from the exit surface 6B. And this emitted light (illumination output 1 ^ is used for the illumination of the liquid crystal display panel 2. 312095 Order ------.-Line-(Please read the precautions on the back before filling out this page) 1234015 A7 V. Description of the invention ( 3: In the conventional liquid crystal display device described above, a problem is that in the curved surface of the light path 6 (: the component light in the surface light source device does not reflect internally, but departs from the outside. There is a reason for this when shooting. When the reflection condition towards the curved surface 6c of the optical path will destroy a part of the incident light. When the part is incident, # 夕 、 隹 /-古 于, which is fully supplied, is neat, but the direction of the entrance from the LED8 is neat, but large. There are a few angles to expand as you are familiar with. If the light guide plate 6 belongs to a ship from & money & resin materials (for example, order PMMA: methyl methyl acid · refractive index is called to bend the light path The angle of 6C is set to a condition of approximately 45 degrees, and the critical angle becomes approximately η. Therefore, in FIG. 9, the light incident on the curved surface 6C of the optical path from the angle of 45 degrees of the incident surface from below is totally reflected. However, it is inclined Several degrees of light (incidence angle is less than the critical angle), a part of it is leaking The light leakage can be reduced by changing the inclination angle of the light path curved surface 6C or the material (refractive index) of the light guide plate 6. However, the inclination angle of the light path curved surface 6 (: cannot be increased from 45 degrees. Moreover, the low-cost guide The material of the light plate is also limited, so it cannot be expected to have such a large refractive index. Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs [Objective and Summary of the Invention] Here, the object of the present invention is to provide a surface light source device that solves the above problems. A liquid crystal display device and an improved light guide plate used in the device. Specifically, a light guide plate improved so that the curved surface of the light path can efficiently perform the direction change of the light path, and a surface light source device and a liquid crystal display using the light guide plate The invention is firstly applicable to an exit surface for outputting light; the size of the back paper is applied to the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 3 312095 1234015 5. Description of the invention The rear surface of the surface; an incident surface provided at the aforementioned back surface for inputting light; A light guide plate with a light path curved surface in the direction of the incident surface. The main point of the improvement of the present invention is to form at least a protrusion on the light curved surface of the light guide plate of this type. The oblique surface extending in the direction of. This protrusion is formed to have a function of bending the optical path by two internal reflections. Moreover, at least one of the protrusions is formed corresponding to the position of the main input light in the incident surface (in general, , On the top of each light source. There may be two or more positions.-According to this basic feature, with respect to the input light from the light source, a curved surface of the optical path is formed to efficiently change the direction of the optical path. This is because, as described above, the internal incidence angle becomes larger when the internal incidence on each inclined surface is caused by the existence of protrusions with inclined surfaces, and the total reflection condition is not easy compared with the conventional case where only incident inside the flat surface (no protrusions). The edge of destruction, that is, 'a large internal angle of incidence, of course, makes total reflection easy and reduces light leakage. 2. As a result, the square path is transformed by the light path f surface, and the amount of light inside the transmission light guide plate is increased. As a result, the brightness of the exit surface is also increased. If it is used in a liquid crystal display device, the display screen becomes brighter. Here, it is considered that when the arrangement interval of the light sources is narrow, or if light input is not carried out at a position slightly separated from the upper surface of the light source, the protrusions are preferably formed repeatedly along the edge portion. L_ ^ is formed at the bottom between adjacent protrusions. M is close to the size of the paper. This paper applies the Chinese national standard (CNSM4 X fierce 7 ϋ) ---- a'-a ^ ^ 4 312095 1234015 —_B7 V. Description of the invention (5 / It is also possible to interrupt in front of the exit surface. Secondly, the surface light source device according to the present invention includes at least one one-person light source and a guide wire. Then, the light guide plate has an exit surface for rotating light; The back face faces the back face of the exit surface; the incident face provided at the edge of the back face for inputting light supplied from the primary light source; and the light path f for allowing the light input through the incident face to move away from the incident face. The curved surface and the above-mentioned improvement are implemented on the curved surface of the optical path. That is, at least one ridge is formed on the curved surface of the optical path, and the protrusion is provided with inclined surfaces for performing optical path bending with two internal reflections. Each inclined surface faces toward The direction extending from the exit surface to the back surface is extended. Then, at least one of the protrusions is formed corresponding to the main input light level in the incident surface. (One or more). For a surface light source device, it is preferable that the protrusions are repeatedly formed along the edges. The lines may be formed at the bottom between adjacent protrusions and may become shallower as they approach the exit surface. It may be interrupted in front of the exit surface. If the surface light source device improved as described above is arranged for the illumination of the liquid crystal display panel, the liquid crystal display device of the present invention can be obtained. [Example] Reference is made to Figs. 1 to 7 The drawings illustrate embodiments of the present invention. In addition, in the drawings, the dimensions, shapes, etc. of each element are appropriately exaggerated for easy understanding. In addition, common symbols are used for elements used in common with FIGS. 8 and 9. , And repeated explanations are omitted as appropriate. _ [First embodiment] This paper size applies the Chinese National Standard (CNS) A4 (210 X 297 mm) 5 312095 1234015 Printed by A7, Employees ’Cooperative, Intellectual Property Bureau, Ministry of Economic Affairs 5 Description of the Invention (6 First, referring to FIG. 1, the schematic structure of the liquid crystal display device of this embodiment is shown. The liquid crystal display device i1 is a liquid crystal display illuminated from the back. 2 is provided with a surface light source device 13. The surface light source device 13 is provided with a light guide plate 16, an LED (point light source) 8, and a reflection plate 5. The light guide plate 16 is a light-transmitting member made of, for example, acrylic resin, and has approximately The wedge-shaped cross section has an exit surface 16B provided by the measurement surface on one side and a back surface 16A provided by the measurement surface on the other side. Optical path curved surface 16c. This optical path curved surface 16C has projections 16K that are repeatedly formed along an imaginary surface inclined at approximately 45 degrees to the exit surface 16B. In other words, the imaginary surface provides the optical path curved surface 16 (: a general surface (excluding the projection 16K) The plane left when outside. The same applies below). As shown in FIG. 1, the protrusions 16K are provided with a pair of inclined surfaces 161 and 16J by being enlarged and shown. Each oblique surface 161, 16J extends in a direction connecting the emission surface 16B and the rear surface 16A. In addition, each of the inclined surfaces 161 and 16J is inclined in the opposite direction to the general surface of the optical path curved surface 16c to form a triangular roof-shaped three-shaped cross section. The intersections of each of the oblique surfaces 161 and 16J correspond to the tops of the sections of each ridge. Note that this top (the intersection of the oblique faces) is approximately 45 degrees inclined from the exit surface 16B. In addition, the repeating pitch (space between adjacent tops) of the protrusions 16K is specified as 50 // m. The size of the relatively protruding 16K has also become smaller. Therefore, each bottom portion formed between adjacent protrusions 16K causes a strong reflection in a line shape 'to prevent this reflection from appearing on the exit surface 16B. This is the so-called ------ order ------, --- line-AW. (Please read the precautions on the back before filling out this page) 1234015 A7 V. Description of the Invention (7 / Shooting)- This kind of type is easy to appear if the size of 16κ is increased to a certain degree. Next, the behavior of the light rays of the liquid crystal display device configured as described below will be described below. For the function of the light path curved surface 16C, refer to Fig. 2. Fig. 2 The light path curved surface 16 is shown in plan view ⑷ and side view (B). If the LED 8 'is turned on, light is introduced into the light guide plate 16 through the incident surface i6D. Most of the introduced light is incident on the inside of the light path. Here, it is 'important' that the curved surface of the optical path is formed unevenly and repeatedly to form a protrusion formed by the oblique surface ⑹, 16J, as in the past (see Figs. 8 and 9). Therefore, the internal incidence is equal to The oblique surface of the protrusion i6i i6j is implemented. Here, from the point of light quantity, the main force that becomes the internal incident light is from the light emitting point of any LED8 to go directly above the incident surface 经过 to the oblique surface. 16I, 16J. Either in Figure 2 or (B) shows an example of a general optical path. Here, the curved surface g of the optical path is represented by the symbol Θ (to be more precise, the general surface representing the top of the Misaki section to the surface M), and the angle of the back surface 16A is generalized. It means that the incident direction from the plane i6D is also drawn from the vertical incidence. There are also a number of tilts in the two figures, from the point of light emission indicated by the symbol P to the top (and approximately perpendicular), and incident on one side. Bevel! 61 Inside: Z7: The light 'is immediately incident internally on the other side again, and is reflected again internally. Here, the angle of incidence when the internal incident is 2 degrees is better than the conventional light path f curved surface 6 c (see Two p anti 7 312095 ------- t --------- (Please read the precautions on the back before filling this page) Line --I '1234015 A7 V. Description of the invention (9) For example The range is from 10 degrees to 70 degrees. However, it is necessary to pay attention to the angle 0, and of course change the most appropriate mitral angle (the angle formed by the inclined surface 16I '16J). (Please read the precautions on the back before filling this page } Furthermore, when the light guide plate 16 is thin, if the angle Θ is set too large, it must be noted that the incident surface 16D can be set. The width becomes narrower. Conversely, if the angle 0 is reduced, the settable width becomes wider as the incident surface 16D. Therefore, the expansion of the degree of freedom of the angle 0 is also an advantage of the present invention. In the conventional optical path curved surface 6C ( (Figures 8 and 9), in fact, you should pay attention to things that can only be selected in a narrow range around 45 degrees. For example, the inclination angle of the curved surface 6C is only less than 45 degrees, and the total reflection condition It is almost unsatisfactory, and the amount of light leakage from the curved surface of the optical path is rapidly increased. Although the present invention adopts a small tilt angle of 0, the total reflection condition is not simply destroyed. In addition, the direction of the optical path L after the 'direction conversion' can also be adjusted by designing the angle (apex angle of the three-section cross section) formed by the inclined surfaces 161 and 16J. Corresponding angle (9 ', the above range of 10 degrees to 70 degrees, the actual selection range of the same apex angle is about 60 degrees to 120 degrees. The Ministry of Economic Affairs, Intellectual Property Bureau, Employee Consumer Cooperatives printed the main optical path L after the direction change. The direction is preferably designed for uniform emission from the exit surface 16B. In general, if the main optical path L and the exit surface 16B are parallel, there will be a tendency to send light from the entrance surface 16 to a distance, and the tilt will be weakened Although this is the outline of the first embodiment, various deformations are allowed for the shape formed on the curved surface of the optical path of the edge of the input light beam of the light guide plate. The second embodiment to the sixth embodiment will be described. These are as follows: This paper standard weekly uses the Chinese National Standard (CNS) A4 specification (21Q x 297 public love)-9 312095 1234015 A7 B / V. Description of the invention (! 〇) [Second Embodiment j Refer to Section 3 Fig. 'On the light guide plate% used in the second embodiment, the light path f curved surface 26C is shown in a plan view from the top to the upper side of the light guide plate 26. The end of the guide plate 26 on the thicker side is provided with a thin and light emitting connection surface. surface( The light path curved surface 26C is not shown). The light path curved surface 26C is inclined with respect to the exit surface 16β: there are a large number of protrusions, the protrusions 26K and the first are implemented :: limit opening / completion corresponding to LED8 marked with a dotted line The position of the luminous point ρ is changed by PI. It is mainly implemented near the position where the light is input to the light guide plate 26. The light path curved surface 26C forms a flat inclined surface (approximately inclined) at a portion where the protrusion 26K is not formed (corresponding to the blank space of the LED8). 45 degrees). Each protrusion 26K is provided with a pair of inclined surfaces 26I and 26J. Each inclined surface 261 and 26J 'extends in a direction connecting the exit surface 26B and the back surface (not shown). Further, each inclined surface 261 and 26J is opposite to The general surfaces of the optical path curved surface 26c are inclined obliquely to each other to form a triangular roof-shaped Mikasa section. The parent line of each beveled surface 261 26J corresponds to the top of each Mikasa section. The size or repeating pitch of the protrusions 26K, and The protrusions of the i-th embodiment may be "the same degree. Incidentally, the inclination of the light path curved surface 26C of the inclined surfaces 261 and 26J with respect to the general surface is based on the position corresponding to the light emitting point P (the position of the main input light). The slope on the side is steeper than the slope on the near side. For example, in the figure 3, 'the slope of the right half slope 261 is steeper than 26J, and the slope of the left half slope 26J is steeper than 261. The difference in slope is As shown in the figure, the farther away from the position corresponding to the light-emitting point P (the main input light position), the clearer the paper scale uses the Chinese National Standard (CNS) A4 specification (210 X 297 public meal 1 — 10 312095 1234015) 5. Description of the invention ( The reason for the difference between the printed point deviation of the consumer cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs and the = Γ oblique difference is that 'inside from the light emitting ^, towards the inside of the inclined plane 261 or the inclined plane 26J, the order is slightly oblique, which corresponds to its observance + The change of direction should be facilitated by private parties.彳 Total reflection condition—the surface is reflected twice. «One way 'The light path curved surface 26 still achieves the direction conversion without waste of the light components separated from the main light (an umbrella line input near the light-emitting point P). As a result, light utilization efficiency can be further improved. [Third Embodiment] The fruit reference ",, and Fig. 4 ', that is, for the light guide plate 36 used in the third embodiment-the plan view ⑷ and the side view W viewed from above the exit surface 36B side show the light path curved surface 36C The light guide has an optical path curved surface 36C connecting the exit surface 36B and the back surface 36A (front end edge of the projection surface) at the end of the thicker side. The optical path curved surface 36C is inclined with respect to the emission surface 36B. The imaginary surface of the dog has 3-6K. Then, the depth of the bottom of these protrusions 36K is toward the position corresponding to the LED8 light emitting point ρ indicated by the dotted line, in other words, as the main input light is from the light guide plate 36 And gradually become shallower. Then, in front of the exit surface 36B, the depth becomes zero and shifts to a flat surface. Moreover, the inclined surfaces 361, 36J are three-dimensionally twisted and rolled surfaces, and the slope of the inclined surface approaches the exit surface 36B. Slows down, smoothly shifts to a flat surface in response to the bottom end. In addition, the shift position (boundary) is fixed so that it is incident inside

------------ ^^ 1 — (Please read the precautions on the back before filling in this page) Order ·-| Line _ 11 312095 1234015 A7 B7 V. Description of the invention (the incidence of light of 12 The angle 0 (refer to FIG. 4B) is greater than the critical angle. According to this embodiment, the internal reflection of the inclined surfaces of the protrusions 36K 361 and 36J easily becomes total reflection, and efficient direction change can be achieved. [Fourth Embodiment] As shown in Fig. 5 ', in the fourth embodiment, a large number of protrusions are repeatedly formed only for a predetermined interval of LeD8. As shown in the simple diagram, each protrusion forms a high ridge on the back side of the light guide plate, and gradually decreases the height of the ridge toward the exit surface. Then, 'is shifted to a flat curved optical path in front of the exit surface. That is, the two bevels are not rolled. As shown in the figure, the protrusions of this embodiment use a flat curved optical path as a reference surface to correspond to a portion where a ridge is formed. Not to mention, a bottom is formed between the ridge and the ridge, and the bottom gradually decreases toward the exit surface and disappears at the position shifted to the flat surface. According to this embodiment, the internal reflection of the oblique surface of the protrusion is easily changed to the total reflection ', and efficient direction change can be achieved. Of course, it is preferable that such a protrusion formation region is provided corresponding to each LED8. (Please read the precautions on the back before filling out this page) 0-• Line-Printing Room for Employees' Cooperatives in the Intellectual Property Bureau of the Ministry of Economic Affairs [Fifth Embodiment] As shown in Figure 6, this embodiment is also only for LED8 Sections repeatedly form a large number of protrusions. As a simple illustration, a deep bottom is formed on the back side of the light guide plate, and the depth of the bottom gradually decreases toward the exit surface. Then, it shifts to a flat curved optical path just in front of the exit surface. Then, a protrusion is formed between the adjacent bottom and the bottom. Each protrusion forms a triangular cross-sectional shape by the intersection of two inclined surfaces. The two bevels are not: shrink. / This paper size is in accordance with the Chinese National Standard (CNS) A4 specification (2i0x 297 public love) 312095 A7 1234015 V. Description of the invention (13) According to this embodiment, the internal reflection of the oblique surface of the protrusion is easily changed to total reflection: possible Achieve efficient direction change. Of course, it is preferable that such a protrusion formation region 'is provided corresponding to each LED8. [Sixth Embodiment] As shown in Fig. 7, in the sixth embodiment, an optical path curved surface 46c of a light guide plate 46 is formed along a general surface that is gently curved. Each of the protrusions is tender and forms a large number of oblique faces having an inclined surface with respect to the curved surface. As shown in the figure, the intersection of the oblique faces forms a curved top and a bottom is formed between adjacent tops. These bottoms describe curved lines as shown by the dotted lines. The depth of the bottom is gradually made shallower from the incident surface 46D side toward the exit surface 46B. In addition, the top corners made by the oblique faces that meet at the top cover the full length of the top to become a $. According to this embodiment M, the internal reflection of the oblique surface of the protrusion easily becomes total reflection, and efficient direction change can be achieved. [Other Modifications] The above-mentioned embodiments are not intended to limit the field of view of the present invention. For example, the following deformations are allowed. (a) In each of the above embodiments, the protrusions cover the entire length of the edge portion, or are limited to the periphery of the main input position of the light to form a plurality. However, depending on the situation, an average protrusion may be formed for each LED, or a unique protrusion may be formed as a whole. However, in this case, it is preferable to increase the size of the protrusions as needed. (b) The form of the protrusion to the curved surface of the optical path in each of the above embodiments may be used in combination. For example, 'form cancer of figure 7 (sixth embodiment) using a curved surface is used in figure 5 (fourth embodiment) or sixth (fourth embodiment), and it is limited to the curved surface as a reference Ridge (figure 5), or G-scale scales applicable to Zhongguanjia Standard (CNS) A4 (2l0X 297 public love) ------ 1 Ί 〇 1 should be combined (1) (21 cread Read the notes on the back before filling out this page} Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economy 1234015 A7 ______ B7 5. The range of the description of the invention (14 / (Figure 6) is also possible.) (E) In the above embodiments In the middle, the oblique surface of the raised blame key forms a sharp roof (squall line) that is directly connected. However, 'stop the direct connection and use a round roof. It is also possible to have rounded corners to form a rounded roof or A sharp roof (crossing line) is also acceptable. (D) Processing of the exit surface or back surface of the light guide plate may be performed as required.

To. For processing, there is an emission promotion II such as transmission through the exit surface or roughening of the back surface, formation of minute protrusions, and the like.调整 In order to adjust various characteristics of the light emitted from the light guide plate, more than one additional plate may be arranged along the output surface. The additional plates are, for example, a tri-panel plate and a light diffusion plate. ⑺As a light guide plate, instead of a transparent tree, it is also possible to use a so-called scattered light guide. The light-scattering light-guiding body 'is a well-known light-guiding body having the ability to scatter, such as particles. b) Although the light guide plate in each of the above embodiments has a wedge-shaped cross section, this is I 4 and does not limit the present invention. For example, a light guide plate having a uniform thickness as a whole may be used, and light may be provided at one end or two or more ends in the above-mentioned manner, and a curved surface may be used. At this time, depending on the position and number of curved surfaces of each optical path ', an appropriate number of point-shaped light emitting sources and incident surfaces are provided. (h) The present invention is applicable to a surface light source device used for applications other than illumination behind a liquid crystal display panel of a liquid crystal display device such as a mobile phone or a portable personal computer, and a light guide plate suitable for use in the device. For example, a surface light source device suitable for front lighting of a liquid crystal display panel may be used. .__ And it can be widely applied to other electronic devices such as LCD TVs. This paper size is applicable to Chinese national standards (CNSM4 Regulation mG x 297 Public Issue'-, 312095 14 1234015

Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. 5. Description of the invention (15) Lighting equipment, liquid crystal display device and light guide plate used in the device. [Brief Description of the Drawings] Fig. 1 is a schematic diagram showing an overall configuration of a liquid crystal display device according to a first embodiment of the present invention in an exploded perspective view. Fig. 2 is a plan view (A) and a side view (B) of the light guide plate used in the embodiment shown in Fig. 1 showing the curved surface of the light path. Fig. 3 is a plan view showing a light path curved surface of the light guide plate used in the second embodiment. Fig. 4 is a plan view (A) and a side view (B) of the light guide plate used in the third embodiment, showing the curved surface of the light path. Fig. 5 is an enlarged view of the periphery of the primary light source for the light guide plate used in the fourth embodiment. FIG. 6 is an enlarged view of the periphery of the primary light source for the light guide plate used in the fifth embodiment. Fig. 7 is a plan view of the light guide plate used in the sixth embodiment without a light path curved surface. Fig. 8 is an exploded perspective view showing the overall arrangement of a liquid crystal display device including a conventional surface light source device using a local light source. Fig. 9 is a sectional view showing the surface light source device shown in Fig. 8. [Explanation of component symbols] 1, 11 LCD display device 2 LCD display panel 3, 1 3 Surface light source device ---- ^ ------.— line—AWI C Please read the precautions on the back before filling in this Page) This paper size is in accordance with Chinese National Standard (CNS) A4 (210 X 297 mm) 15 312095 [234015 A7 B7 V. Description of the invention (16

6 '16' 26 '36 6A ^ 16A ^ 26A 6B, 16B, 26B 6C, 16C, 26C 6D > 16D > 26D

46 36A > 46A 36B, 46B 36C, 46C 36D-46D

16K '26K ~ 36K' 46K Light guide plate Back side of the light guide plate Light path of the back of the light guide plate Curved surface Incident surface protrusion of the light guide plate 161, 16J, 261, 26J, 361, 36J Protruding slope ------- order- ----.— Line— (Please read the notes on the back before filling out this page) Printed by the Intellectual Property Bureau Staff Consumer Cooperatives of the Ministry of Economic Affairs This paper is sized to the Chinese National Standard (CNS) A4 (210 X 297 mm) 16 312095

Claims (1)

1234015 VI. Scope of patent application L A light guide plate having an exit surface for outputting light; a back face facing the back surface of the exit surface; a light input provided at the entrance surface t of the back edge portion; The light input from the incident surface faces an optical path curved surface away from the incident surface, wherein the optical path curved surface forms at least one protrusion, and the protrusion has an inclined surface extending in a direction connecting the exit surface and the back surface, so that The internal light path is bent twice, and at least one of the protrusions just described corresponds to a position where the input light is mainly implemented in the aforementioned incident surface. 2 · If the scope of patent application is the first! In the light guide plate of the item, the protrusion is repeatedly formed along the edge portion. 3 · If the scope of patent application is the first! The light guide plate according to item 2 or item 2, wherein the light guide plate is formed at the bottom between adjacent protrusions and becomes shallower as it approaches the aforementioned exit surface. 4. If the light guide plate of the third item of the application is applied, the aforementioned bottom is interrupted in front of the aforementioned exit surface. 5. A surface light source unit comprising a surface light source device including at least one primary light source and a light guide plate, wherein 'otherwise said light guide plate has an exit surface for outputting light; The direction P indicates the back surface of the light exit surface, an incident surface provided at the edge of the back surface for inputting light supplied by the primary light source, and a distance from the incident surface for the light input through the incident surface. The light guide plate with a curved light path in the direction is characterized in that at least one protrusion is formed on the f surface of the light path f. This dog has a square connecting the exit surface and the back surface. ----- ^ -------— ^ —— 9. (Please read the precautions on the back before filling this page) 1234015 A8 B8 C8 D8 Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs Range extension: An oblique surface, so that the internal light path is bent twice. At least one of the protrusions corresponds to ^, and T should be formed at the position where the input light is mainly applied on the incident surface. 6. As for the 5th item in the scope of patent application, the above-mentioned, +, # μ Jiuyuan device in which the aforementioned protrusions are repeatedly formed along the edge. 7. == The surface light source device of the item 5 or 6 of the range, wherein the bottom portion ′ of the dog shape becomes shallower as it approaches the aforementioned exit surface. 8. As stated in the scope of the patent, the meaning of item 7, +, & free You Yuanzhi, where the aforementioned bottom is interrupted in front of the projection surface. 9. A liquid crystal display device, which is a liquid crystal display device that uses a surface light source device to illuminate a liquid crystal display panel, wherein the surface light source device includes at least one secondary light source and a light guide plate, and the light guide plate has a function of outputting light. The exit surface facing the back surface of the exit surface; the incident surface provided at the edge of the back surface for inputting light supplied by the primary light source; and the light passing through the incident surface away from the incident surface The light guide plate with a curved optical path in a planar direction is characterized in that the curved surface of the optical path is formed with at least one protrusion, and the protrusion is provided with an inclined surface extending in a direction connecting the exit surface and the rear surface, so that the optical path is bent twice inside. At least one of the protrusions is formed at a position where the input light is mainly implemented in the incident surface. 10. If the liquid crystal display device according to item 9 of the scope of patent application, wherein the aforementioned protrusions --------------------- order ---- 11 ----- line! (Please read the precautions on the back before filling in this page) This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 18 312095 1234015 as C8 D8 6. The scope of patent application is repeatedly formed along the aforementioned edge . 11. The liquid crystal display device according to item 9 or 10 of the scope of patent application, wherein the liquid crystal display device is formed at the bottom between adjacent protrusions and becomes shallower as it approaches the exit surface. 12. The liquid crystal display device according to claim 11 in which the aforementioned bottom portion is interrupted in front of the aforementioned exit surface. -------------------- Order— — · —Line— (Please read the precautions on the back before filling out this page) Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs The size of the paper is applicable to the Chinese National Standard (CNS) A4 (210 X 297 mm) 19 312095