JP3700904B2 - Light guide plate, side light type surface light source device, and liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light guide plate, a sidelight-type surface light source device, and a liquid crystal display device, and in particular, a light guide plate in which protrusions by a pair of inclined surfaces are repeatedly formed along an incident surface on a surface facing a light exit surface of a plate-shaped member; The present invention can be applied to a sidelight type surface light source device and a liquid crystal display device using this light guide plate. In the present invention, a projection projecting from the side surface is formed on the exit surface side from the imaginary line dividing the side surface of the plate member in the thickness direction of the plate member, so that the surface facing the exit surface of the plate member is formed. In the configuration in which the protrusions formed by the pair of inclined surfaces are repeatedly formed, abnormal light emission can be prevented even if the protrusions are formed on the side surfaces of the plate-like member.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, for example, in a liquid crystal display device, a liquid crystal display panel is illuminated by a sidelight type surface light source device, thereby reducing the overall shape.
[0003]
That is, in the sidelight type surface light source device, a primary light source composed of a rod-shaped light source is disposed on the side of a plate-like member (that is, composed of a light guide plate), and illumination light emitted from the primary light source is guided from the end surface of the light guide plate to the light guide plate. Is incident on. Further, the sidelight type surface light source device bends the illumination light and emits the light from the plane of the light guide plate toward the liquid crystal display panel, whereby the overall shape can be reduced.
[0004]
Such a sidelight type surface light source device has a method in which the light guide plate is formed with a substantially uniform plate thickness and a method in which the thickness of the light guide plate is gradually reduced as the distance from the primary light source increases. The latter can emit illumination light more efficiently than the former.
[0005]
18 is an exploded perspective view showing an example of the latter sidelight type surface light source device 1, and FIG. 19 is a cross-sectional view taken along line AA in FIG. In this sidelight type surface light source device 1, a primary light source 3 is disposed on the side of a light guide plate 2, and a reflection sheet 4, a light guide plate 2, a light diffusion sheet 5, and prism sheets 6 and 7 made of a light control member are sequentially stacked. Formed.
[0006]
The primary light source 3 is formed by surrounding a fluorescent lamp 8 made of a cold cathode tube with a reflector 9, and illuminates light from an opening side of the reflector 9 to an end surface (hereinafter referred to as an incident surface) 2 </ b> A of the light guide plate 2. . Here, the reflector 9 is formed of, for example, a sheet material that regularly or irregularly reflects incident light.
[0007]
The light guide plate 2 is formed of a transparent member, for example, acrylic (PMMA resin) by injection molding so as to have a wedge-shaped cross section, and the illumination light of the primary light source 3 is incident from an incident surface 2A that is an end surface. Thereby, the light guide plate 2 repeatedly reflects between the side surface 2B of the reflection sheet 4 (hereinafter referred to as the back surface) and the side surface 2C of the light diffusion sheet 5 (hereinafter referred to as the output surface) to propagate the illumination light. During reflection on the exit surface 2C, a component having a critical angle or less is emitted from the back surface 2B and the exit surface 2C.
[0008]
Further, the light guide plate 2 has a light scattering surface 2D formed on the back surface 2B. Here, as shown in FIG. 20, the light scattering surface 2D is made of, for example, magnesium carbonate or titanium oxide as a pigment so that the degree of light scattering gradually increases from the incident surface 2A side toward the wedge-shaped tip. It is formed by selectively adhering light scattering ink. The light scattering surface 2D may be formed by partially forming the back surface 2B on a satin surface (texture surface) instead of the light scattering ink. In this case as well, the light scattering surface 2D forms a satin-ground region at a constant pitch or randomly, for example, in a rectangular shape, and the area of each rectangular region increases from the incident surface 2A side toward the wedge-shaped tip. It is formed to increase. As a result, the light guide plate 2 makes the light quantity distribution of the emitted light uniform over substantially the entire area of the emission surface 2C.
[0009]
In this way, the light guide plate 2 that emits illumination light basically reflects repeatedly between the back surface 2B and the exit surface 2C and propagates the illumination light, while reflecting on the exit surface every time it is reflected by the back surface 2B. The incident angle of illumination light is reduced, and a component having a critical angle or less is emitted from the emission surface 2C. Therefore, the directivity of the illumination light emitted from the emission surface 2C is a directivity inclined toward the tip of the wedge shape.
[0010]
The light diffusion sheet 5 is made of a sheet material having light diffusibility, and further scatters illumination light emitted from the emission surface 2C of the light guide plate 2 so that the light scattering surface 2D is not recognized. The shine, shadow, etc. of each part of the light guide plate 2 illuminated by the
[0011]
The prism sheets 6 and 7 are arranged to correct the directivity of the light guide plate 2. That is, the prism sheets 6 and 7 are formed of a light-transmitting sheet material such as polycarbonate, and a prism surface is formed on the surface opposite to the light guide plate 2 side. This prism surface is repeatedly formed with triangular projections with a pair of inclined surfaces. In the prism sheet 6, these projections are repeatedly formed along the side surface 2G of the light guide plate 2. In the prism sheet 7, these projections are formed. It is repeatedly formed along the incident surface of the light guide plate 2. Thus, the prism sheets 6 and 7 correct the main emission direction of the emitted light to the front direction of the emission surface 2C with the pair of inclined surfaces.
[0012]
In the sidelight type surface light source device 1 according to such an illumination light emission principle, the reflection sheet 4 is formed by a sheet-like regular reflection member made of a metal foil or the like, or a sheet-like irregular reflection member made of a white PET film or the like. The illumination light leaking from the back surface 2B is reflected and incident on the light guide plate 2, thereby improving the utilization efficiency of the illumination light.
[0013]
The sidelight type surface light source device that emits illumination light in this way is mounted on a personal computer or the like integrally with the liquid crystal panel, held by a frame or the like. Accordingly, the sidelight type surface light source device needs to be able to easily and reliably position and hold the light guide plate 2 with respect to a holding member such as a frame. In particular, in the sidelight type surface light source device, if the light guide plate 2 collides with the fluorescent lamp 8 due to an impact or the like, the fluorescent lamp 8 may be damaged, and the light guide plate 2 is securely moved so as not to move to the fluorescent lamp 8 side. It is necessary to hold the positioning.
[0014]
Thus, depending on the sidelight type surface light source device, as shown in FIG. 21, a convex portion 2H is integrally formed on the side surface 2G of the light guide plate 2, and the convex portion 2H is positioned and held on the frame of the light guide plate 2 by this convex portion 2H. It was made.
[0015]
[Problems to be solved by the invention]
By the way, in this type of side light type surface light source device, if the projections formed by a pair of inclined surfaces are repeatedly formed on the back surface 2B of the light guide plate 2, the illumination light can be efficiently transmitted as compared with the case where the back surface 2B is formed by a flat surface. It turned out that it can emit.
[0016]
That is, in this sidelight type surface light source device, a projection having a triangular cross section with a pair of inclined surfaces is repeatedly formed on the back surface 2B of the light guide plate 2 along the entrance surface 2A, and the light diffusion sheet 5 on the exit surface 2C. In addition, the prism sheet 7 is omitted, and the prism sheet 6 is disposed in such a direction that the prism surface faces the light guide plate 2 (that is, the prism surface downward), contrary to that shown in FIGS. 17 and 18. The
[0017]
The light guide plate 2 corrects the direction of the illumination light reflected by the back surface 2B to the front direction of the exit surface 2C in the in-plane direction along the incident surface by the pair of repeatedly formed inclined surfaces. As a result, when the back surface 2B is configured as a flat surface, the light guide plate 2 is incident on the output surface 2C with a small incident angle even when the illumination light component is totally reflected on the output surface 2C with a large incident angle. The illumination light is emitted efficiently and the utilization efficiency of the illumination light is improved. Further, in the in-plane direction along the incident surface, the directivity of the illumination light emitted from the emission surface 2C is emphasized in the front direction of the emission surface 2C.
[0018]
However, in the side light type surface light source device of this configuration, when the projection 2H equivalent to the conventional one is formed on the side surface (see FIG. 21), the region having a high luminance level in a stripe shape from the root of the projection 2H toward the center of the light guide plate 2 AR1 was observed, and it was found that so-called abnormal light emission occurred on the exit surface 2C.
[0019]
The present invention has been made in consideration of the above points. In a configuration in which protrusions with a pair of inclined surfaces are repeatedly formed on the back surface of the light guide plate, abnormal light emission is prevented even if the protrusions are formed on the side surfaces of the light guide plate. A light guide plate, a sidelight type surface light source device, and a liquid crystal display device using the sidelight type surface light source device are proposed.
[0020]
[Means for Solving the Problems]
  In order to solve this problem, in the invention of claim 1, the light incident from the end face of the plate-like member is emitted from the emission surface of the plate-like member in the process of propagating through the inside of the plate-like member. In the light guide plate, the protrusions formed by a pair of inclined surfaces are repeatedly formed on the back surface of the plate member in the extending direction of the end surface,Excluding the end face and the face facing the end faceOn the side surface of the plate-like member, a projection protruding from the side surface is formed on the emission surface side from a virtual line dividing the side surface in the thickness direction of the plate-like member.Then, the thickness of the base of the protrusion protruding from the side surface farthest from the end face is formed thinner than the end face side of the part..
[0021]
  According to a second aspect of the present invention, in the sidelight type surface light source device, the illumination light emitted from the predetermined light source is incident from the end surface of the plate-like member, and the illumination light is bent and emitted from the emission surface of the plate-like member. , Repeatedly forming protrusions with a pair of inclined surfaces on the back surface of the plate-like member in the direction in which the end faces extend,Excluding the end face and the face facing the end faceProtrusions projecting from the side surface of the side surface of the plate-like member are formed on the emission surface side from the virtual line dividing the side surface in the thickness direction of the plate-like member.Then, the thickness of the base of the protrusion protruding from the side surface farthest from the end face is formed thinner than the end face side of the part..
[0022]
  According to a third aspect of the present invention, in the configuration of the second aspect, the protrusion is connected to the end surface.InForm on the end face side from the center of the opposing face and end faceThe
[0023]
  And claims4In the invention of claim 2,Or claim 3The liquid crystal display panel is illuminated by the sidelight type surface light source device described in 1).
[0024]
  In the light guide plate configured such that light incident from the end face of the plate-like member is emitted from the exit surface of the plate-like member in the process of propagating through the inside of the plate-like member as in the configuration of claim 1 , Repeatedly forming a pair of sloped protrusions on the back surface of the plate-like member in the direction in which the end face extends,Excluding the end face and the face facing the end faceA projection that is brightly illuminated by illumination light by forming a projection that protrudes from the side surface of the side surface of the plate-like member on the emission surface side from a virtual line that divides the side surface in the thickness direction of the plate-like member. The roots of the projections are formed small, and the roots of the brightly illuminated projections are formed away from the pair of slopes, whereby the roots of the brightly illuminated projections are visually recognized from the exit surface and are generated at a high luminance level. The streak area can be made difficult to perceive.Further, in this configuration, if the thickness of the base at the part farthest from the end face of the protrusion protruding from the side surface is formed thinner than the part on the end face side from the part, the side farther from the end face, The roots of the projections that are brightly illuminated by the illumination light can be made smaller, and the streak-like region with a higher luminance level can be made harder to perceive.
[0025]
  Further, as in the configuration of claim 2, the side light type surface light source device that makes the illumination light emitted from the predetermined light source incident from the end face of the plate member, bends the illumination light and emits it from the emission surface of the plate member. Then, on the back surface of the plate-like member, a protrusion with a pair of inclined surfaces is repeatedly formed in the direction in which the end surface extends,Excluding the end face and the face facing the end faceIf a protrusion protruding from the side surface is formed on the emission surface side of the imaginary line dividing the side surface of the plate member in the thickness direction of the plate member, the base of the protrusion brightly illuminated by the illumination light is formed small In addition, the roots of the brightly illuminated projections are formed away from the pair of slopes, and thereby the roots of the brightly illuminated projections are visually recognized from the exit surface, thereby generating streaky regions having a high luminance level. Can be perceived difficult.Further, in this configuration, if the thickness of the base at the part farthest from the end face of the protrusion protruding from the side surface is formed thinner than the part on the end face side from the part, the side farther from the end face, The roots of the projections that are brightly illuminated by the illumination light can be made smaller, and the streak-like region with a higher luminance level can be made harder to perceive.
[0026]
  Further, as in the configuration of claim 3, the tip protrusion is formed on the end surface.InIn the configuration in which the plate member is formed so that the plate thickness decreases as the distance from the end surface increases from the center between the opposing surface and the end surface, the protrusion can be formed on the thick plate portion. By keeping the roots of the brightly illuminated protrusions away from the pair of slopes, it is possible to make the streaky areas with high brightness levels difficult to perceive.The
[0027]
  Claim by these4As in the configuration of claim 2,Or claim 3A high-quality display screen can be formed by illuminating the liquid crystal display panel with the sidelight type surface light source device described in 1. above.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
[0029]
(1) First embodimentPrerequisite configuration
  FIG. 1 shows a side light type surface light source device according to the first embodiment of the present invention in comparison with FIG.Prerequisite compositionFIG. The sidelight type surface light source device 10 is formed by housing a reflection sheet 4, a light guide plate 12, a prism sheet 6, and a primary light source 3 in a frame 11 that is a frame. In this side light type surface light source device 10, the same components as those of the side light type surface light source device 1 of FIG. 18 are denoted by the corresponding reference numerals, and redundant description is omitted. Further, as the reflection sheet 4, a diffuse reflection member made of a white PET film is applied.
[0030]
Here, the light guide plate 12 is formed of a transparent member such as acrylic by injection molding so as to have a wedge-shaped cross section, and the illumination light of the primary light source 3 is incident from an incident surface 12A that is an end surface. As a result, the light guide plate 12 repeatedly reflects between the back surface 12B and the exit surface 12C to propagate the illumination light L (see FIG. 18), and a part of the back surface is reflected on the back surface 12B and the exit surface 12C. The light is emitted from 12B and the emission surface 12C.
[0031]
The light guide plate 12 is repeatedly formed with minute protrusions along the incident surface 12A on the back surface 12B, as partially shown by the arrow C on the incident surface 12A side. Here, the protrusion is formed in a triangular shape by directly connecting a pair of inclined surfaces 12E and 12F extending in a direction orthogonal to the incident surface 12A. As a result, the light guide plate 12 corrects the directivity of the emitted light in the front direction of the emission surface 12C (the normal direction of the emission surface 12C) in the plane parallel to the incident surface 12A and efficiently emits the illumination light. The light quantity emitted from 12C is increased.
[0032]
In this embodiment, the light guide plate 12 has a pair of inclined surfaces 12E and 12F formed at an equal inclination with respect to the exit surface 12C, and the angle formed by the inclined surfaces 12E and 12F is selected to be about 100 degrees. Yes. The apex angle can be appropriately selected within the range of 50 degrees to 130 degrees to obtain practical characteristics, but is preferably within the range of 60 degrees to 110 degrees. Further, in the light guide plate 12, these minute protrusions are, for example, a repetition pitch W1 of 50 [μm], which is smaller than 1/4 of the pixel period of the liquid crystal display panel to which the sidelight type surface light source device 10 is applied. It is formed by.
[0033]
Further, the light guide plate 12 is provided with a light emission promoting surface that promotes the emission of the illumination light L on the emission surface 12C. Here, the light emission promoting surface is formed so that the degree of promoting the emission of illumination light increases from the wedge-shaped tip of the light guide plate 12 toward the incident surface 12A of the light guide plate 12. In this embodiment, the light emission promoting surface is constituted by a light scattering surface that scatters illumination light, and the degree of scattering of the illumination light increases as it goes from the wedge-shaped tip of the light guide plate 12 toward the incident surface 12A. Configured. Thereby, the light guide plate 12 increases the amount of emitted light that is insufficient on the incident surface 12A side (thick wall side) of the light guide plate 12, and makes the amount of emitted light uniform.
[0034]
That is, as shown in FIG. 2, the light scattering surface is formed by partially roughening the exit surface 12C into a circular shape (dot shape) by mat surface processing (hereinafter, a region roughened into this circular shape). Is called a light scattering pattern). Here, the light scattering pattern 13 is formed to have a small diameter (for example, a diameter of 50 μm or less) that is difficult to perceive with the naked eye when viewed from the exit surface 12C side. Further, as indicated by reference characters D and E, the light scattering patterns 13 are arranged so that the number per unit area decreases from the vicinity of the fluorescent lamp 8 of the light guide plate 12 toward the wedge-shaped tip.
[0035]
Specifically, the light guide plate 12 measures an emitted light amount distribution when no light scattering pattern 13 is formed on the exit surface 12C, and the area of the light scattering pattern 13 arranged per predetermined unit area is determined from the measured light amount distribution. (Hereinafter referred to as the coverage) is calculated for the entire exit surface 12C. Further, according to this coverage, as indicated by symbols E and D in FIG. 2, frames are set by varying the pitch so that the pitch increases toward the wedge tip, and light scattering is caused by irregular arrangement in each frame. Pattern 13 is arranged. As a result, the light guide plate 12 forms a light emission promoting surface that makes it difficult for the light scattering pattern 13 to be recognized by the naked eye from the emission surface 12C side.
[0036]
Further, the light guide plate 12 is formed with protrusions (positioning protrusions) 12H on the side surface 12G, and the protrusions 12H are engaged with the recesses 11A formed on the frame 11 and positioned on the frame 11.
[0037]
Here, the projection 12H is formed in a columnar shape having a rectangular cross section, and is formed so that the surface on the exit surface 12C side is flush with the exit surface 12C. Further, the protrusion 12H is cut off at the base portion, as shown in FIG. 3, on the thick incident surface 12A side of the light guide plate 12, and the side surface 12G of the light guide plate 12 is divided in the thickness direction of the light guide plate 12. It is offset from the imaginary line M toward the exit surface 12C. Thus, the protrusion 12H is formed so that the edges E1 and E2 extending in the direction perpendicular to the emission surface 12C out of the edges E1 to E3 formed at the base of the side surface 12G are shortened and orthogonal to this edge. About the length of a direction, even if it shortens edge E1 and E2 in this way, it is made by the length which can ensure sufficient intensity | strength.
[0038]
In the above configuration, the illumination light L emitted from the fluorescent lamp 8 (see FIG. 1) and (see FIG. 19) is reflected directly or after being reflected by the reflector 9, and then enters the light guide plate 12 from the incident surface 12A. The illumination light L propagates inside the light guide plate 12 while being repeatedly reflected between the back surface 12B and the exit surface 12C. At this time, every time the illumination light L is reflected by the back surface 12B, the incident angle with respect to the emission surface 12C decreases, and a component having a critical angle or less with respect to the emission surface 12C is emitted from the emission surface 12C. Further, at this time, the illumination light L is urged to be emitted from the emission surface 12C by the light emission promotion surface formed on the emission surface 12C of the light guide plate 12, and the amount of emitted light in the direction from the incident surface 12A side toward the wedge-shaped tip is It is made uniform.
[0039]
In this way, part of the illumination light that enters the light guide plate 12 and propagates through the light guide plate 12 is reflected by the side surface 12G of the light guide plate 12 and propagates through the light guide plate 12. At this time, as shown in FIGS. 4 to 6, in the light guide plate 12 having the protrusion formed on the side surface 12 </ b> G, the edges E <b> 1 to E <b> 3 formed at the root of the protrusion 12 </ b> H are brightly illuminated by the illumination light L.
[0040]
Further, the illumination light L propagating in the light guide plate 12 is scattered by the light diffusion pattern (FIG. 2) formed on the exit surface 12C, but most of the light propagates from the entrance surface 12A toward the wedge-shaped tip. As a result, of the edges formed at the base of the protrusion 12H, the edges E1 and E2 extending in the direction perpendicular to the emission surface are illuminated more brightly than the edge E3 parallel to the emission surface, and also to the emission surface. Of the edges E1 and E2 extending in the vertical direction, the edge E1 on the wedge-shaped tip side is more brightly illuminated than the edge E2 on the incident surface side.
[0041]
As shown in FIG. 4, in the light guide plate in which a pair of inclined surfaces are repeatedly formed on the back surface, when the same protrusion is formed as in the case of the light guide plate having the back surface formed by a flat surface, the edge that is brightly illuminated in this way E1 and E2 are reflected and observed by the respective slopes formed on the back surface, thereby generating an area AR1 having a high luminance level in a linear shape (see FIG. 21).
[0042]
As shown in FIG. 5, when the back surface is formed of a flat surface, the illumination light L that brightly illuminates the edges E1 and E2 in this way is mostly reflected by the exit surface 12C and is reflected on each part of the light guide plate 12. This sort of area AR1 with a high luminance level is not visible. On the other hand, when a slope is formed on the back surface, the illumination light reflected by the back surface due to the presence of the slope is incident on the exit surface at a small incident angle, so that it is emitted from the exit surface and is visually recognized. A high level area AR1 is observed.
[0043]
In contrast to the generation principle of the area AR1 having a high luminance level, in this embodiment, as shown in FIG. 6, the edges E1 and E2 extending in the direction perpendicular to the emission surface 12C are formed to be short. As a result, the portion that is brightly illuminated is reduced accordingly, and the region with a high luminance level is more difficult to observe than the exit surface 12C.
[0044]
Further, as shown in FIG. 7, the protrusion 12 </ b> H is on the light incident surface side of the light guide plate 12, and emerges from an imaginary line M that divides the side surface 12 </ b> G of the light guide plate 12 in the thickness direction of the light guide plate 12. By being offset toward the 12C side, the edges E1 and E2 are formed so as to be separated from the back surface 12B. On the other hand, the illumination light L that brightly illuminates the edges E1 and E2 is scattered when reflected by the edges E1 and E2. Thus, in this embodiment, the illumination light L that brightly illuminates the edges E1 and E2 is distributed in each direction until reaching the separated back surface 12B, and is also visually recognized through the exit surface 12C. It becomes difficult.
[0045]
The illumination light L emitted from the emission surface 12C in this way is scattered by the light diffusion pattern 13 formed on the emission surface 12C, which makes it difficult to visually recognize the area AR1 having a higher luminance level, which is practically sufficient. Abnormal light emission on the exit surface is prevented to a certain extent.
[0046]
According to the above configuration, in the configuration in which the protrusions by the pair of inclined surfaces 12E and 12F are repeatedly formed on the back surface 12B of the light guide plate 12, the light guide plate 12 has the light incident surface side 12A, A projection 12H protruding from the side surface 12G is formed at a position offset from the imaginary line M dividing the side surface 12G in the thickness direction of the light guide plate 12 toward the emission surface 12C, thereby brightening the illumination light at the base of the projection 12H. The illuminated edge can be made difficult to see from the exit surface 12C, and abnormal light emission on the exit surface can be prevented.
[0047]
(2)Reference example of this application
  FIG. 8 in comparison with FIG.According to reference examples not included in the present inventionIt is sectional drawing which shows the light-guide plate 22 applied to a sidelight type surface light source device. This light guide plate 22 is a range in which the side surface 22G of the light guide plate 22 is offset from the imaginary line dividing the light guide plate 22 in the thickness direction of the light guide plate 22 toward the output surface 22C side in the first embodiment.As for the premise constitution of the above-mentionedA protrusion 22H is formed so as to be offset from the light guide plate 12 toward the back surface. The light guide plate 22 is formed in the same shape as the above-described light guide plate 12 except that the projections 22H are formed at different positions.
[0048]
  As shown in FIG. 8, even if the protrusion 22H is formed on the back surface side in the range where the side surface of the light guide plate 22 is shifted to the emission surface 22C side from the imaginary line dividing the light guide plate 22 in the thickness direction, the first EmbodimentPrerequisite configurationThe same effect can be obtained.
[0049]
(3) No.1EmbodimentExamples of
  FIG. 9 shows the first aspect of the present invention.1It is a perspective view which expands and shows the part of protrusion 32H about the light-guide plate 32 applied to the sidelight type surface light source device which concerns on this embodiment. The light guide plate 32 is formed in the same shape as the light guide plate 12 described above except that the shape of the protrusion 32H is different.
[0050]
That is, as shown in FIG. 10 in comparison with FIG. 3, in this light guide plate 32, the protrusion 32H is formed in a columnar shape with a trapezoidal cross section so that the base is thin on the side farther from the incident surface 32A.
[0051]
According to the configuration shown in FIG. 9 and FIG. 10, the projection AR is formed so that the root is thin on the wedge-shaped tip side that is most brightly illuminated, so that the linear area AR1 having a high luminance level can be obtained. Furthermore, recognition can be made more difficult.
[0052]
(4) No.2Embodiment
  FIG. 11 shows a comparison of FIG.2It is a perspective view which expands and shows the part of protrusion 42H about the light-guide plate 42 applied to the sidelight type surface light source device which concerns on this embodiment. The light guide plate 42 is formed in the same shape as the light guide plate 12 described above except that the shape of the protrusion 42H is different.
[0053]
  Here, the protrusion 42H has the above-described first.1After rising from the side surface 42G with the same cross-sectional shape as the protrusion 32H in the embodiment, the tip end side is bent into the back surface 42B side. Accordingly, the protrusion 42H is configured to enlarge the area of the side surface for positioning.
[0054]
  As shown in FIG. 11, even if the side surface area for positioning is enlarged on the tip side of the projection,1As in the embodiment, abnormal light emission on the exit surface can be prevented. Further, as the area of the side surface of the protrusion is increased, the position of the light guide plate 42 can be further stabilized by effectively avoiding the dropout from the recess formed in the frame.
[0055]
(5) No.3Embodiment
  FIG. 12 shows the first aspect of the present invention by comparison with FIG.3It is a perspective view which expands and shows the part of protrusion 52H about the light-guide plate 52 applied to the sidelight type surface light source device which concerns on this embodiment. The light guide plate 52 is formed in the same shape as the light guide plate 42 described above except that the shape of the protrusion 52H is different.
[0056]
  Here, the protrusion 52H has the above-mentioned first.1The root portion is formed by the same cross-sectional shape as the protrusion 32H in the embodiment. Further, the protrusion 52H is formed so that the cross-sectional shape gradually increases on the back surface side as the distance from the root increases so that the area of the side surface for positioning increases sequentially.
[0057]
  According to the configuration shown in FIG. 12, even if the cross-sectional shape is gradually enlarged on the back surface side as the distance from the root increases,1The same effect as in the embodiment can be obtained. Further, by gradually expanding the cross-sectional shape on the back surface side, it is possible to improve the releasability of the light guide plate during molding.
[0058]
(6) Other embodiments
In the above-described embodiment, the case where the protrusion is formed so that the cross-sectional shape of the root portion is rectangular or trapezoidal has been described. However, the present invention is not limited to this, and the point is that the root is formed on the wedge-shaped tip side. Protrusions are formed so that the thickness of the portion is reduced, and the same effect as in the above-described embodiment can be obtained. That is, in the cross-sectional shape of the root portion, as shown in FIG. 13, an arc-shaped protrusion formed by the emission surface and a flat surface may be formed, and as shown in FIG. 14, the emission surface is flat. It is good also as the triangular shape formed by the smooth surface. Further, as shown in FIGS. 15 and 16, a rectangular shape distorted so that a side intersecting with the emission surface is inclined with respect to the emission surface may be used. Moreover, as shown in FIG. 17, it is good also as an inverted trapezoid shape formed by the output surface and the flat surface.
[0059]
Further, in the above-described embodiment, the case where the protrusion is formed by rising from the side surface of the light guide plate with the quadrangular shape of the root portion is described, but the present invention is not limited to this, and the triangular pyramid, quadrangular pyramid shape, etc. A protrusion may be formed.
[0060]
Furthermore, in the above-described embodiment, the case where the inclined surface is formed with the same inclination on the back surface has been described. However, the present invention is not limited to this, and the inclination of the pair of inclined surfaces may be varied.
[0061]
Further, in the above-described embodiment, a case has been described in which a pair of inclined surfaces formed on the back surface is directly connected to form a triangular cross-sectional protrusion, but the present invention is not limited to this, for example, when connecting by a curved surface Furthermore, the present invention can be widely applied to the case where the slope itself is formed by a curved surface.
[0062]
Further, in the above-described embodiment, the case where the light scattering pattern is randomly arranged by setting the frame by changing the pitch and irregularly arranging the light scattering pattern in the frame has been described. The invention is not limited to this, and as shown by reference numerals D1 and E1 in FIG. 2, the light diffusion pattern may be arranged by combining regular arrangement and irregular arrangement, and in the same manner as a conventional light guide plate. Thus, the present invention can be widely applied to the formation of a light diffusion surface.
[0063]
In the above embodiment, the light guide plate is formed of a transparent member. However, the present invention is not limited to this, and the light guide plate is formed of various members as long as the effects of the present invention can be obtained. The present invention can be widely applied to such cases.
[0064]
In the above-described embodiment, the case where the prism sheet is laminated on the light exit surface of the light guide plate has been described, but the present invention is not limited thereto, and when the light diffusion sheet is disposed between the light guide plate and the prism sheet, Furthermore, in place of these, or in addition to these, various members such as a polarization separation sheet that selectively transmits illumination light of a desired polarization plane and reflects the polarization plane orthogonal thereto are arranged. It can be widely applied when arranged.
[0065]
Furthermore, in the above-described embodiment, the case where the illumination light is incident from one end face has been described. However, the present invention is not limited to this, and the side light type surface light source device configured to receive the illumination light from another end face is also provided. Can also be widely applied.
[0066]
Furthermore, in the above-described embodiment, the case where the present invention is applied to a sidelight type surface light source device using a light guide plate made of a plate-shaped member having a wedge-shaped cross section has been described. The present invention can be widely applied to a side light type surface light source device using a flat plate having a substantially uniform thickness as an optical plate.
[0067]
Further, in the above-described embodiment, the case where the primary light source is configured by the fluorescent lamp made of a rod-shaped light source has been described. However, the present invention is not limited thereto, and a plurality of point light sources such as light emitting diodes are arranged to form the primary light source. It can be widely applied to cases.
[0068]
Further, in the above-described embodiment, the case where the present invention is applied to the surface light source device of the liquid crystal display device has been described. However, the present invention is not limited to this, and the sidelight type surface light source device such as various illumination devices and display devices. Can be widely applied to.
[0069]
【The invention's effect】
As described above, according to the present invention, the projection of the plate member is emitted by forming a projection protruding from the side surface on the emission surface side from the imaginary line dividing the side surface of the plate member in the thickness direction of the plate member. A surface light source device having a high-quality light emitting surface capable of preventing abnormal light emission even when a protrusion is formed on a side surface of a plate-like member in a configuration in which a protrusion formed by a pair of inclined surfaces is repeatedly formed on a surface facing the surface. And a liquid crystal display device using the same can be realized.
[Brief description of the drawings]
FIG. 1 is a first embodiment of the present invention.Prerequisite configurationIt is a disassembled perspective view which shows the sidelight type surface light source device which concerns on.
2 is a plan view showing an exit surface of a light guide plate in the sidelight type surface light source device of FIG. 1. FIG.
FIG. 3 is a cross-sectional view showing a side surface of a light guide plate by taking a cross section at a base portion of a protrusion.
FIG. 4 is a perspective view for explaining an abnormal light emission on an emission surface.
FIG. 5 is a perspective view for explaining the case where the back surface is formed as a flat surface in comparison with FIG. 4;
FIG. 6 shows the first embodiment in comparison with FIG.Prerequisite configurationIt is a perspective view with which it uses for description of the prevention principle of abnormal light emission of the light-guide plate which concerns on.
7 is a front view of FIG. 6. FIG.
FIG. 8 is a comparison with FIG.Reference exampleIt is sectional drawing which shows the light-guide plate applied to the sidelight type surface light source device which concerns on.
FIG. 9 shows the first of the present invention.1It is a perspective view which expands partially and shows the light-guide plate applied to the sidelight type surface light source device which concerns on this embodiment.
10 is a cross-sectional view showing the light guide plate of FIG. 9 in comparison with FIG. 3;
FIG. 11 shows the first of the present invention.2It is a perspective view which expands partially and shows the light-guide plate applied to the sidelight type surface light source device which concerns on this embodiment.
FIG. 12 shows the first of the present invention.3It is a perspective view which expands partially and shows the light-guide plate applied to the sidelight type surface light source device which concerns on this embodiment.
13 is a cross-sectional view showing a light guide plate applied to a sidelight type surface light source device according to another embodiment in comparison with FIG.
14 is a cross-sectional view showing a light guide plate in which the cross-sectional shape of the base portion of the protrusion is formed in a triangular shape by comparison with FIG.
15 is a cross-sectional view showing a light guide plate in which the cross-sectional shape of the base portion of the protrusion is formed in a quadrangular shape in comparison with FIG.
16 is a cross-sectional view showing a light guide plate having a cross-sectional shape of a protrusion different from that in FIG.
FIG. 17 is a cross-sectional view showing a light guide plate with a cross-sectional shape of a protrusion that is further different from those in FIGS. 15 and 16;
FIG. 18 is an exploded perspective view showing a conventional sidelight type surface light source device.
FIG. 19 is a cross-sectional view taken along line AA in FIG.
20 is a plan view showing the back surface of the light guide plate of FIG. 18. FIG.
FIG. 21 is a perspective view for explaining the abnormal light emission on the emission surface.

Claims (4)

A light guide plate configured such that light incident from the end surface of the plate-like member is emitted from the emission surface of the plate-like member in the process of propagating through the inside of the plate-like member,
On the back surface of the plate-like member, a protrusion with a pair of inclined surfaces is repeatedly formed in the direction in which the end surface extends,
Protrusions protruding from the side surface on the emission surface side of the imaginary line dividing the side surface in the thickness direction of the plate-like member, on the side surface of the plate-like member excluding the end surface and the surface facing the end surface. Forming ,
A light guide plate characterized in that a thickness of a base at a part farthest from the end face of the protrusion protruding from the side surface is formed thinner than a part closer to the end face than the part . In the sidelight type surface light source device that makes the illumination light emitted from the predetermined light source incident from the end face of the plate member, bends the illumination light and emits it from the emission surface of the plate member,
On the back surface of the plate-like member, a protrusion with a pair of inclined surfaces is repeatedly formed in the direction in which the end surface extends,
Protrusions protruding from the side surface on the emission surface side of the imaginary line dividing the side surface in the thickness direction of the plate-like member, on the side surface of the plate-like member excluding the end surface and the surface facing the end surface. Forming ,
A sidelight type surface light source device characterized in that a thickness of a base at a part farthest from the end face of the protrusion protruding from the side face is formed thinner than a part on the end face side from the part . The protrusion and the center of and the surface facing the said end surface said end face, side light type surface light source device according to claim 2, characterized in that formed on the end face side. A liquid crystal display device illuminates a liquid crystal display panel with the sidelight type surface light source device according to claim 2 .

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