JP5299771B2 - Surface emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformize emission light and to enhance brightness, relating to a surface light-emitting device where a plurality of dots containing white pigments are printed on a light guide plate. <P>SOLUTION: The surface light-emitting device includes a light guide plate 1 with end faces 14a and 14b which allow transmission of incident light, a reflecting surface 12 which is perpendicular to the end faces 14a and 14b and on which a plurality of dots 11 containing white pigments reflecting the transmission light from the end faces 14a and 14b are printed, and a display surface 13 which faces the reflecting surface 12 and emits reflection light from the reflecting surface 12, as well as light sources 2a and 2b that are positioned along the end faces 14a and 14b to emit incident light. The plurality of dots 11 differ in weight density of the white pigments depending on positions of the reflecting surface 12. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a surface light emitting device in which a plurality of dots containing a white pigment are printed on a light guide plate.

  In a surface light emitting device used as a backlight for liquid crystal display or a display lamp such as a signboard, a light guide plate that converts linear incident light into planar output light, a light source positioned along the light guide plate, There is a side light type (edge light type) surface light-emitting device having FIG. 13 is a cross-sectional view illustrating an example of a configuration of a main part of a sidelight surface emitting device.

  In the surface light emitting device 101 shown in FIG. 13, light emitted from the light sources 20 a and 20 b respectively covered with the reflectors 30 a and 30 b is incident on the end surfaces 140 a and 140 b of the light guide plate 100. The incident light is transmitted through the end faces 140 a and 140 b and reflected by the reflection surface 120 or the reflection sheet 40 of the light guide plate 100. These reflected lights are emitted from the display surface 130 and are sequentially transmitted through the diffusion sheet 60 and the lens sheet 50.

  FIG. 14 is a plan view of the light guide plate 100 viewed from the reflection surface 120.

  As shown in FIG. 14, a plurality of dots 110 are printed on the reflecting surface 120 in order to make the luminance of the light emitted from the display surface 130, that is, the emitted light of the surface light emitting device 101 uniform over the entire display surface. . The plurality of dots 110 increase in area as their positions on the reflecting surface 120 move away from the light sources 20a and 20b. This is because the dot area density (the area of the dots occupying per unit area of the reflecting surface) is increased as the distance from the light source on the reflecting surface increases, and the amount of incident light that becomes non-uniform according to the distance from the light source. The amount of reflected light is adjusted so that the luminance of the emitted light is uniform over the entire display surface.

  As described above, for example, Patent Document 1 discloses an apparatus that attempts to make the luminance of emitted light uniform by printing dots having different areas on the reflection surface of a light guide plate.

  In general, the plurality of dots printed on the reflection surface of the light guide plate includes a white pigment, and the weight concentration of the white pigment contained in each dot (the white pigment contained per unit mass of the dot). (Mass) is the same as shown in FIG. FIG. 15 shows the change in the weight concentration of the white pigment of the dots 110 with respect to the distance from the light source 20a.

Hei 6-265730

  In the surface light emitting device, it is required not only to make the emitted light uniform but also to increase the luminance. In order to increase the brightness of the emitted light, there are means for engraving a lens groove on the light guide plate instead of printing dots, means for forming irregularities by molding, and the like. However, with these means, especially when the light guide plate is large (screen size is 19 inches or more) or thin (thickness is 0.2 mm or less), advanced machining techniques are necessary and expensive, so there is a problem in mass productivity. There is. Thus, there is a demand for increasing the brightness of emitted light in a surface light emitting device such as the surface light emitting device 101 in which dots are printed on a light guide plate.

  In order to increase the luminance of the emitted light by the surface light emitting device 101, the weight concentration of the white pigment contained in the dots 110 may be increased. However, in this case, in order to uniformly adjust the luminance of the emitted light, it is necessary to reduce the dot area density in the region near the light source on the reflecting surface. Then, on the reflecting surface, the distribution of dots is sparse, and dark portions where dots are not printed increase, so that the luminance uniformity of the entire surface is impaired. Therefore, in the surface light emitting device 101, when increasing the brightness of the emitted light, the upper limit of the weight concentration of the white pigment is limited, thereby preventing the brightness of the emitted light from being increased.

  An object of the present invention is to enable uniform emission light and high brightness in a surface light emitting device in which a plurality of dots containing a white pigment are printed on a light guide plate.

In order to achieve the above object, a surface light emitting device according to the present invention comprises:
A light guide plate comprising: an end surface that transmits incident light; a reflective surface that is orthogonal to the end surface; and a display surface that faces the reflective surface and emits reflected light from the reflective surface; and a position along the end surface In the surface light emitting device having the line light source that emits the incident light, a plurality of dots including a white pigment that reflects the transmitted light from the end surface is printed on the reflection surface, and the printing of the plurality of dots is performed. a projection region where the end face bleeds through the region, there is an adjacent region adjacent to the projection area, the plurality of dots, the respective positions in the reflective surface, have different weight concentration of the white pigment The weight concentration of the white pigment in the projection area increases as the distance from the line light source located along the end surface corresponding to the projection area increases, and the weight concentration of the white pigment in the adjacent area increases from the line light source. After decreasing with distance, characterized in that it increases again.

  According to the present invention, since the brightness of the emitted light is adjusted by changing the weight concentration of the white pigment contained in the dots, the emitted light can be made uniform and the brightness can be increased.

It is sectional drawing which shows the structure of the principal part of the surface emitting device of Embodiment 1. It is the top view which looked at the light-guide plate provided in the surface emitting device of Embodiment 1 from the reflective surface. FIG. 3 is a diagram showing a change in weight concentration of a white pigment of dots 110 with respect to a distance from a light source 2a in the surface light emitting device shown in FIG. In the surface emitting device shown in FIG. 2, it is a figure which shows the other example of the weight density change of the white pigment of the dot 110 with respect to the distance from the light source 2a. It is the top view which looked at the light-guide plate provided in the surface emitting device of Embodiment 2 from the reflective surface. FIG. 6 is a diagram showing a change in weight concentration of a white pigment of dots 110 with respect to a distance from a light source 2a in the surface light emitting device shown in FIG. FIG. 6 is a diagram showing another example of a change in the weight concentration of the white pigment of the dots 110 with respect to the distance from the light source 2a in the surface light emitting device shown in FIG. It is the top view which looked at the light-guide plate provided in the surface emitting device of Embodiment 3 from the reflective surface. It is the top view which looked at the light-guide plate provided in the surface emitting device of Embodiment 4 from the reflective surface. It is sectional drawing which shows the structure of the principal part of the surface emitting device of Embodiment 5. It is the top view which looked at the light-guide plate provided in the surface emitting device of Embodiment 6 from the reflective surface. In the surface emitting device shown in FIG. 11, it is a figure which shows the weight density change of the white pigment of the dot 110 with respect to the distance from the light source 2a. It is sectional drawing which shows an example of a principal part structure of the surface light-emitting device of a sidelight system. It is the top view which looked at the light-guide plate provided in the surface light-emitting device shown in FIG. 13 from the reflective surface. In the surface emitting device shown in FIG. 13, it is a figure which shows the weight density change of the white pigment of the dot 110 with respect to the distance from the light source 20a.

(Embodiment 1)
The surface light-emitting device of this embodiment will be described. FIG. 1 is a cross-sectional view illustrating a configuration of a main part of the surface light-emitting device of Embodiment 1.

  In the surface light emitting device 10 shown in FIG. 1, the light source 2a is disposed along the end surface 14a of the light guide plate 1, and the light source 2b is disposed along the end surface 14b. The light sources 2a and 2b are, for example, lamps, and are covered with the reflectors 3a and 3b, respectively.

  The light guide plate 1 includes a reflective surface 12 that is orthogonal to the end surfaces 14 a and 14 b and a display surface 13 that faces the reflective surface 12. The shape of the light guide plate 1 is not limited to a plate shape as shown in FIG. 1, and may be a wedge shape in which the interval between the reflective surface 12 and the display surface 13 is gradually narrowed, for example.

  A diffusion sheet 6 is attached to the display surface 13, and a lens sheet 5 is attached to the diffusion sheet 6. On the other hand, a plurality of dots 11 are printed on the reflective surface 12, and the reflective sheet 4 is attached. Here, the dots 11 printed on the reflecting surface 12 will be described in detail.

  FIG. 2 is a plan view of the light guide plate 1 as seen from the reflecting surface 12.

As shown in FIG. 2, a plurality of dots 11 having the same shape and area are printed on the reflecting surface 12 at regular intervals. The white pigment contained in each dot is a white and highly reflective material typified by silicon dioxide (SiO ₂ ), barium sulfate (BaSO ₄ ), titanium dioxide (TiO ₂ ), and magnesium oxide (MgO). Is used. However, the weight concentration of the white pigment is not constant. FIG. 3 is a diagram showing a change in the weight concentration of the white pigment of the dots 110 with respect to the distance from the light source 2a in the surface emitting device shown in FIG. In FIG. 3, the vertical axis indicates the weight concentration of the white pigment. On the other hand, the horizontal axis indicates the distance from the light source 2a, and the position farthest from the light source 2a is the position closest to the light source 2b.

  As shown in FIG. 3, on the reflection surface 12, dots 11 having a higher white pigment weight concentration are printed in regions farther from the light sources 2a and 2b. Thereby, in the reflective surface 12, a reflectance becomes high as it leaves | separates from the light sources 2a and 2b. Examples of a method for printing the dots 11 on the reflection surface 12 include screen printing, offset printing, and inkjet printing. When printing the dots 11 on the reflecting surface 12 by screen printing or offset printing, inks having different white pigment weight concentrations may be prepared and printed in several steps. When printing the dots 11 on the reflecting surface 12 by ink jet printing, printing can be performed at once by putting inks having different weight concentrations of white pigments into a plurality of tanks. Therefore, printing time is longer than screen printing or offset printing. Can be shortened.

  In the surface light emitting device 10, light emitted from the light sources 2 a and 2 b is transmitted through the end surfaces 14 a and 14 b and introduced into the light guide plate 1. At this time, since the light sources 2a and 2b are respectively covered with the reflectors 3a and 3b, the light emitted from the light sources 2a and 2b efficiently enters the end surfaces 14a and 14b.

  The transmitted light from the end surfaces 14 a and 14 b is reflected by the plurality of dots 11 printed on the reflection surface 12 or the reflection sheet 4 and emitted from the display surface 13. At this time, the amount of light incident on the reflecting surface 12 (transmitted light from the end surfaces 14a and 14b) decreases as the position is farther from the light sources 2a and 2b. Since the reflectance is high, the luminance of the emitted light from the display surface 13 is uniform over the entire surface.

  Also, since the weight concentration of the white pigment contained in the dot is changed according to the distance from the light source, the white pigment contained in the dot is constant, and only the dot area density is changed to adjust the brightness of the emitted light Unlike the above, the upper limit of the weight concentration of the white pigment is not limited. Therefore, it is possible to increase the brightness of the emitted light. The emitted light from the display surface 13 is sequentially transmitted through the diffusion sheet 6 and the lens sheet 5, thereby further improving the luminance uniformity.

  In the present embodiment, the weight concentration of the white pigment contained in the dots 11 increases uniformly with increasing distance from the light sources 2a and 2b as shown in FIG. 3, but as shown in FIG. The distribution may be such that after increasing from 2b, it decreases once and then increases again. This is for eliminating the dark lines generated on the display surface 13 by the end surfaces 14 a and 14 b being reflected on the reflection surface 12 and making the luminance of the emitted light uniform on the entire display surface 13. The reflection surface 12 has a projection area where the end faces 14a and 14b are reflected, and the light reflected from the projection area and emitted from the display surface 13 has lower luminance than the light reflected from the adjacent area adjacent to the projection area. Become. Therefore, up to the projection area, the dark line is eliminated by increasing the weight concentration of the white pigment as the distance from the light sources 2a and 2b increases. However, if the weight density of the white pigment of the dots printed in the adjacent area is made equal to that of the dots printed in the projection area, the luminance of the light reflected from the adjacent area and emitted from the display surface 13 becomes too high. Therefore, in the adjacent region, the weight concentration of the white pigment contained in the dots 11 is reduced as the distance from the light sources 2a and 2b increases. If the weight concentration of the white pigment continues to decrease, the amount of incident light on the reflecting surface 12 is not uniform, and the uniformity of the emitted light from the display surface 13 is impaired. For this reason, the brightness of the emitted light on the display surface 13 is uniformly adjusted over the entire surface by increasing the white pigment concentration again from the light sources 2a and 2b from the point where the uniformity is impaired.

(Embodiment 2)
The surface light-emitting device of this embodiment will be described. The surface light-emitting device of this embodiment has the same configuration of the main part as compared with the surface light-emitting device 10 of the first embodiment, and the printing state of the dots 11 on the reflection surface 12 is different. FIG. 5 is a plan view of the light guide plate provided in the surface light-emitting device of Embodiment 2 as seen from the reflection surface.

  In the surface light emitting device 20 shown in FIG. 5, dots 11 having a larger area are printed on the reflective surface 12 at regular intervals in the region of the reflective surface 12 that is farther from the light sources 2a and 2b. In the surface light emitting device 20, as shown in FIG. 6, the weight concentration of the white pigment contained in the dots 11 is higher in the region away from the light sources 2 a and 2 b on the reflection surface 12, as in the surface light emitting device 10. Thereby, similarly to the surface light-emitting device 10, the reflectance increases as the distance from the light sources 2a and 2b increases on the reflecting surface 12. As shown in FIG. 7, in the present embodiment as well, in the same manner as in the first embodiment, the weight concentration of the white pigment contained in the dots 11 increases in the projection area and decreases in the adjacent area on the reflection surface 12. There may be.

  In the present embodiment, not only the weight concentration of the white pigment contained in the dots 11 but also the dot area density on the reflecting surface 12 is used as a means for making the luminance of the emitted light from the display surface 11 uniform. Further improvement.

(Embodiment 3)
The surface light-emitting device of this embodiment will be described. The surface light-emitting device of this embodiment has the same configuration of the main part as compared with the surface light-emitting device 10 of the first embodiment, and the printing state of the dots 11 on the reflection surface 12 is different. FIG. 8 is a plan view of the light guide plate provided in the surface light emitting device of Embodiment 3 as seen from the reflection surface.

  In the surface light emitting device 30 shown in FIG. 8, the number of dots 11 is larger in the reflective surface 12 in a region away from the light sources 2 a and 2 b. In the surface light emitting device 30, as shown in FIG. 6, the weight concentration of the white pigment contained in the dots 11 is higher in the region away from the light sources 2 a and 2 b on the reflecting surface 12, as in the surface light emitting device 10. Thereby, similarly to the surface light-emitting device 10, the reflectance increases as the distance from the light sources 2a and 2b increases on the reflecting surface 12. As shown in FIG. 7, in the present embodiment as well, in the same manner as in the first embodiment, the weight concentration of the white pigment contained in the dots 11 increases in the projection area and decreases in the adjacent area on the reflection surface 12. There may be.

  In the present embodiment, not only the weight concentration of the white pigment contained in the dots 11 but also the dot area density on the reflecting surface 12 is used as a means for making the luminance of the emitted light from the display surface 11 uniform. Further improvement.

(Embodiment 4)
The surface light-emitting device of this embodiment will be described. The surface light-emitting device of this embodiment has the same configuration of the main part as compared with the surface light-emitting device 10 of the first embodiment, and the printing state of the dots 11 on the reflection surface 12 is different. FIG. 9 is a plan view of the light guide plate provided in the surface light-emitting device of Embodiment 4 as seen from the reflection surface.

  In the surface light emitting device 40 shown in FIG. 9, dots 11 having a larger area are printed at a higher density in a region of the reflecting surface 12 that is farther from the light sources 2a and 2b. Further, as shown in FIG. 6, in the surface light emitting device 40, the weight concentration of the white pigment contained in the dots 11 is higher in the region away from the light sources 2 a and 2 b on the reflecting surface 12, as in the surface light emitting device 10. Thereby, similarly to the surface light-emitting device 10, the reflectance increases as the distance from the light sources 2a and 2b increases on the reflecting surface 12. As shown in FIG. 7, in the present embodiment as well, in the same manner as in the first embodiment, the weight concentration of the white pigment contained in the dots 11 increases in the projection area and decreases in the adjacent area on the reflection surface 12. There may be.

  In the present embodiment, not only the weight concentration of the white pigment contained in the dots 11 but also the area and density of the dots on the reflecting surface 12 are used as means for equalizing the luminance of the emitted light from the display surface 11. The property is further improved.

(Embodiment 5)
The surface light-emitting device of this embodiment will be described. The surface light-emitting device of this embodiment has the same configuration of the main part as compared with the surface light-emitting device 10 of the first embodiment, and the printing state of the dots 11 on the reflection surface 12 is different. FIG. 10 is a cross-sectional view illustrating a configuration of a main part of the surface light-emitting device of Embodiment 5.

  In the surface light emitting device 50 shown in FIG. 10, the dots 11 whose thickness is increased in a region away from the light sources 2 a and 2 b on the reflection surface 12 are printed with high density. In the surface light emitting device 50, as shown in FIG. 6, the weight concentration of the white pigment contained in the dots 11 is higher in the region away from the light sources 2 a and 2 b on the reflecting surface 12, as in the surface light emitting device 10. Thereby, in the surface light-emitting device 50, since the total amount of the white pigment increases as the dots 11 are further away from the light sources 2a and 2b on the reflection surface 12, the transmittance is reduced. That is, the reflectance increases as the distance from the light sources 2a and 2b increases on the reflecting surface 12. As shown in FIG. 7, in the present embodiment as well, in the same manner as in the first embodiment, the weight concentration of the white pigment contained in the dots 11 increases in the projection area and decreases in the adjacent area on the reflection surface 12. There may be.

  In the present embodiment, not only the weight concentration of the white pigment contained in the dots 11 but also the thickness of the dots on the reflection surface 12 are used as means for making the luminance of the emitted light from the display surface 11 uniform. Further improvement.

(Embodiment 6)
The surface light-emitting device of this embodiment will be described. The surface light-emitting device of this embodiment has the same configuration of the main part as compared with the surface light-emitting device 10 of the first embodiment, and the printing state of the dots 11 on the reflection surface 12 is different. FIG. 11 is a plan view of the light guide plate provided in the surface light emitting device of Embodiment 6 as seen from the reflection surface.

  In the surface light emitting device 60 shown in FIG. 11, the entire surface of the reflecting surface 12 is printed with uniform dots. In addition, as shown in FIGS. 12A and 12B, the surface light emitting device 60 has the same weight concentration of the white pigment contained in the dots 11 as the light sources 2 a and 2 b on the reflecting surface 12 as in the surface light emitting device 10. The distance from the center of the light source 2a, 2b (y direction) becomes higher at the same time. Thereby, similarly to the surface light-emitting device 10, the reflectance increases as the distance from the light sources 2a and 2b increases on the reflecting surface 12. As shown in FIG. 4, in this embodiment as well, the weight concentration of the white pigment contained in the dots 11 increases in the projection area and decreases in the adjacent area on the reflecting surface 12 as in the first embodiment. There may be.

  In the present embodiment, since the weight concentration of the white pigment contained in the dots 11 is changed not only in the x direction but also in the y direction so as to make the luminance of the emitted light uniform, the uniformity is further improved. .

1, 100 Light guide plate 2a, 2b, 20a, 20b Light source 3a, 3b, 30a, 30b Reflector 4, 40 Reflective sheet 5, 50 Lens sheet 6, 60 Diffusion sheet 10, 20, 30, 40, 50, 60, 101 surface Light emitting device 11, 110 Dot 12, 120 Reflective surface 13, 130 Display surface

Claims (2)

A light guide plate comprising: an end surface that transmits incident light; a reflecting surface that is orthogonal to the end surface; and a display surface that faces the reflecting surface and emits reflected light from the reflecting surface;
In a surface light emitting device having a linear light source located along the end face and emitting the incident light ,
The reflective surface is printed with a plurality of dots containing a white pigment that reflects the transmitted light from the end surface, and the print region of the plurality of dots is adjacent to the projection region and the projected region where the end surface is reflected There is an adjacent region, and the plurality of dots have different weight concentrations of the white pigment depending on their positions on the reflecting surface, and the weight concentration of the white pigment in the projection region corresponds to the projection region. A surface light emitting device characterized in that it increases with distance from a line light source located along the end surface, and the weight concentration of the white pigment in the adjacent region decreases and then increases again with distance from the line light source . The surface emitting device according to claim 1, wherein the white pigment material contains barium sulfate or magnesium oxide .

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