JP5179908B2 - Surface light source lighting device - Google Patents

Description

  The present invention relates to a light guide plate and a surface light source illumination device.

  FIG. 1 is a perspective view of a tandem surface light source device (surface light source illumination device) disclosed in Patent Document 1. FIG. In FIG. 1, reference numerals BL <b> 1 and BL <b> 2 denote first and second light guide blocks (light guide plates) arranged in tandem. One end face of each of the light guide blocks BL1 and BL2 is an incident end face 511 and 512, and light from the light sources (for example, cold cathode tubes) 501 and 502 enters. And the light which entered from the entrance end surfaces 511 and 512 of each light guide block BL1 and BL2 is radiate | emitted upward from the light-projection surfaces 521 and 522 of the upper surface of each light guide block BL1 and BL2.

  By the way, in the conventional tandem type surface light source device shown in FIG. 1, linear light sources (for example, cold cathode tubes) are used as the light sources 501 and 502. In this case, the light guide blocks BL1 and BL2 are used. Even if the light sources 501 and 502 are arranged in the vicinity of the incident end faces 511 and 512, color unevenness does not occur in the light guide blocks BL1 and BL2, but light with uneven color is emitted from the light guide blocks BL1 and BL2. Light is not emitted), but instead of the linear light sources (for example, cold cathode tubes) 501 and 502, the linear light sources (for example, cold cathode tubes) 501 and 502 are positioned (light guide block BL1). , BL2 in the vicinity of the incident end faces 511, 512), a plurality of monochromatic point light sources (for example, red (R) point light source, green (G) point light source, blue (B) point light source) are incident. Length of end face (incident end face) When arranged at a predetermined interval in the x, the color unevenness in the light guide blocks BL1, BL2 occurs, light generated color unevenness disadvantageously be light emitted from the light guide blocks BL1, BL2. In particular, in recent years, area control control for adjusting the brightness and chromaticity of a liquid crystal illumination surface light source device according to a display image has been required in a high-quality and large-sized thin TV, and the tandem surface light source device has a single-color spot shape. There is an increasing demand for using a light source, and it is desired to solve the above problems.

  In order to solve such a problem, the inventor of the present application initially places a plurality of monochromatic point light sources in the length direction x of the light incident end face at predetermined intervals in FIGS. 2 to 4. As shown, it has been found that the point light source arrays may be arranged at a distance D sufficient for the light emitted from each point light source to spread and be mixed at the light incident end face. FIG. 2 is a cross-sectional view of a surface light source device (surface light source illumination device) in which point light source arrays are arranged at a distance D sufficient to spread light emitted from each point light source and be mixed at the light incident end face. 3 is a diagram showing a light guide plate used in the surface light source device (surface light source illumination device) of FIG. 2, and FIG. 4 is a portion indicated by reference numeral 212 in FIG. 3 (derived from each point light source). It is a figure for demonstrating the color mixture in the space to the light-incidence end surface of an optical plate.

  In FIG. 2, 11 to 14 are the first to fourth light sources, 21 to 24 are the first to fourth light guide plates, and 7 is an optical film (diffusion plate, if necessary, a diffusion film, (Prism lens) 41 to 44 are light guide plate holding members (L-shaped angles) in the first to fourth stages, 5 is a shade forming a first-stage color mixing area, and 6 is a housing.

  Referring to FIG. 3, the light guide plate 2 (21, 22, 23, 24) includes a light incident end surface 2a into which light from a light source enters, a counter light incident end surface 2b facing the light incident end surface 2a, An emission surface 2g for emitting illumination light, a bottom surface 2h facing the emission surface 2g, and a side surface 2i sandwiched between the emission surface 2g and the bottom surface 2h are provided. In the example of FIG. 3, the thickness of the light guide plate 2 decreases from the light incident end surface 2a toward the counter light incident end surface 2b. Although not shown, a recess for arranging the light source of the light guide plate module at the next stage may be formed in the vicinity of the anti-incident light end surface 2b of the bottom surface 2h. In addition, in order to maintain the laminated structure of the light guide plate 2 (21, 22, 23, 24), the light incident end surface 2a of the light guide plate 2 overlaps with the counter light incident end surface 2b of the previous light guide plate (notch portion). ) Is provided. In general, in order to hold the laminated structure of the light guide plates, each light guide plate is attached to a holding member such as a metal or resin L-shaped angle or a wave structure (for example, Patent Document 2) integrated with them. The structure to wear is often adopted.

  In FIG. 4, the first to fourth light sources 11 to 14 in FIG. 2 are shown as 1 (1R, 1G, 1B,...). In FIG. 4, the range indicated by the symbol A is a mixed color range.

  2 to 4, the distance from the point light source 1 to the light incident end surface 2a generally depends on the directivity characteristics of the light source. For example, when a light source that emits Lambertian light is used as the point light source, as illustrated in FIG. 4, the distance D from the point light source 1 to the light incident end surface 2a is the arrangement pitch of the point light sources. Is approximately equal to P.

According to the configuration of FIGS. 2 to 4, a plurality of monochromatic point light sources 1 are emitted from each point light source 1 even when arranged at a predetermined interval P in the length direction x of the light incident end surface 2a. The light (for example, light having a Lambertian directivity) is mixed in a portion indicated by reference numeral 212 in FIG. 3 (space from each point light source 1 to the light incident end surface 2a of the light guide plate 2). Thus, since light is incident on the light incident end face 2a of the light guide plate 2 (21, 22, 23, 24), light having no color unevenness can be emitted from the light exit surface 2g of the light guide plate.
Japanese Patent No. 3373427 JP 2002-72204 A

  However, in the configurations of FIGS. 2 to 4, in order to mix the light from the plurality of monochromatic point light source arrays 1, a space for mixing colors (mixed color area) is set by placing a distance between the light incident end face 2a and the light source 1. If 212 is provided, there is a problem that the light utilization efficiency deteriorates.

  FIG. 5 is a diagram for explaining the problem of the configuration of FIGS. In FIG. 5, the monochromatic point light source 1 is replaced with a point light source 100 for simplification. When light rays are emitted from the point light source 100 within a range of ± 90 degrees, the emitted light rays are directly incident on the light guide plate 2 (light rays emitted within a range of α in FIG. 5) and a color mixing space ( It is divided into light rays that interfere with the wall surface of the color mixture region 212 (light rays emitted in the range of β and β ′ in FIG. 5). Usually, the wall surface of the color mixing region 212 uses a high reflectance member having a reflectance of 90% or more, but a loss of 10 to several percent is still unavoidable. The light beam that interferes with the wall surface of the mixed color region 212 is expected to interfere with the wall surface a plurality of times before reaching the light guide plate after being reflected by the wall surface, and the light beam is attenuated each time the light beam is reflected by the wall surface.

Considering the simplified model shown in FIG. 5, α = 2 tan ⁻¹ (T / 2D). Here, D is the distance from the light source 100 to the light incident end face 2a of the light guide plate 2, and T is the height of the color mixture region 212. From the above formula, the smaller the height T of the color mixture region 212 is, the smaller the proportion of light rays that are directly incident on the light guide plate 2 and the greater the proportion of light rays that interfere with the wall surface of the color mixture region 212. Further, if the distance D from the light source 100 to the light incident end surface 2a of the light guide plate 2 is increased, the proportion of light directly incident on the light guide plate 2 is reduced, and the proportion of light rays that interfere with the wall surface is increased. That is, if the thickness of the surface light source device is reduced and the distance of the color mixture space (color mixture region) 212 is sufficiently secured, the reflection loss on the wall surface of the color mixture region 212 increases and the light use efficiency deteriorates. There is. For this reason, luminance decreases or power consumption increases to compensate for it.

  The present invention provides a light guide plate capable of mixing light from a plurality of single-color point light sources without reducing light utilization efficiency even when light from a plurality of single-color point light sources is incident. An object of the present invention is to provide a surface light source illumination device.

In order to achieve the above object, the invention according to claim 1 is the first light guide plate module when one light guide plate and a light source for allowing predetermined light to enter the light guide plate are one light guide plate module. A surface light source illumination device using a plurality of second light guide plate modules and third light guide plate modules,
The light guide plate of each light guide plate module is
When light of a plurality of colors is incident from the light incident end surface with a predetermined interval in the length direction of the light incident end surface, the light having a plurality of colors incident from the light incident end surface is mixed. A light guide plate comprising a mixed color region and an effective region having a light emitting surface for emitting light from the mixed color region on the upper surface,
The effective area of the light guide plate decreases from the color mixture area side toward the side opposite to the color mixture area (anti-light-incident end face), and the thickness on the counter-incident light end face side decreases. Part is provided ,
The color mixing region of the light guide plate has a structure in which another light guide plate can be superimposed on at least a part of the region without increasing the overall thickness, and the upper surface of the effective region. As a parallel part having a bottom surface parallel to the light exit surface, and between the parallel part of the color mixing region and the effective region, the parallel part has a predetermined inclination angle with respect to the upper surface and / or the bottom surface of the parallel part. An inclined portion having an inclined upper surface connecting the upper surface of the active region and the upper surface of the effective region,
The parallel part has the same or increased thickness as it goes from the light incident end face toward the inclined part,
The inclined portion has the same or increased thickness from the parallel portion of the color mixture region toward the effective region,
The surface light source illumination device is configured such that the light guide plate of the first light guide plate module and the light guide plate of the second light guide plate module are overlapped, and the light guide plate of the second light guide plate module and the third light guide plate module The light guide plates of other light guide plate modules are overlapped in a manner of overlapping the light guide plates of
The effective region where the thickness of the light guide plate of the first light guide plate module does not change is superimposed on the parallel portion in the color mixture region of the second light guide plate module,
On the inclined portion in the color mixture region of the second light guide plate module, a portion where the thickness of the first light guide plate module on the side opposite to the light incident end surface is reduced is superimposed,
The anti-incident light end face of the first light guide plate module is located at the boundary between the effective area of the light guide plate and the inclined portion of the second light guide plate module,
The effective area where the thickness of the light guide plate of the second light guide plate module does not change is superimposed on the parallel portion in the color mixture area of the third light guide plate module,
A portion where the thickness of the second light guide plate module on the light incident end face side is reduced is overlapped on the inclined portion in the color mixture region of the third light guide plate module;
The anti-incident light end face of the second light guide plate module is located at the boundary between the effective region of the light guide plate and the inclined portion of the third light guide plate module,
The light exit surface of the light guide plate of the first light guide plate module, the light exit surface of the light guide plate of the second light guide plate module, and the light exit surface of the light guide plate of the third light guide plate module are connected flat. And
The light source of the first light guide plate module, the light source of the second light guide plate module, and the light source of the third light guide plate module are mounted on one substrate,
The bottom surface of the parallel portion of the light guide plate of the first light guide plate module, the bottom surface of the parallel portion of the light guide plate of the second light guide plate module, and the bottom surface of the parallel portion of the light guide plate of the third light guide plate module. The light guide plate of the first light guide plate module, the light guide plate of the second light guide plate module, and the light guide plate of the third light guide plate module are arranged on a flat surface. It is a surface light source illumination device .

The invention according to claim 2 is the surface light source illuminating device according to claim 1, wherein each of the light guide plates of the first light guide plate module, the second light guide plate module, and the third light guide plate module comprises:
The predetermined inclination angle of the inclined upper surface of the inclined portion of the color mixture region is less than 30 °,
It is characterized in that the angle is more than an angle at which another light guide plate can be superimposed on at least a part of the mixed color region without increasing the overall thickness.

Further, the invention according to claim 3 is the surface light source illuminating device according to claim 1 or 2, wherein each light source of the first light guide plate module, the second light guide plate module, and the third light guide plate module is:
A red point light source, a green point light source, and a blue point light source are repeatedly arranged at predetermined intervals in the length direction of the light incident end face of the light guide plate,
Alternatively, a package in which a red point light source, a green point light source, and a blue point light source are arranged at a predetermined ratio is arranged at a certain interval in the length direction of the light incident end face of the light guide plate. This is a surface light source illumination device.

The invention according to claim 4 is the surface light source illuminating device according to claim 3, wherein each light guide plate of the first light guide plate module, the second light guide plate module, and the third light guide plate module is:
Luminance distribution control processing is performed on the bottom surface and / or the exit surface of the effective region, and the color mixture region is not subjected to diffuse reflection processing as light extraction means .

According to the first and second aspects of the invention, when the light guide plate allows light of a plurality of colors to enter from the light incident end surface at a predetermined interval in the length direction of the light incident end surface, Since it has a color mixing area that has the function of mixing light of multiple colors that have entered from the light incident end face, it also reduces the efficiency of light utilization when light from multiple monochrome point light sources is incident. In addition, light from a plurality of single-color point light sources can be mixed. In addition, each light guide plate is configured by sequentially superimposing the preceding light guide plate on at least a part of the mixed color region, so that light from a plurality of single-color point light sources is received. Even in the case of incident light, illumination with high light use efficiency is possible. Since each light source of the plurality of light guide plate modules is mounted on one substrate, the number of members can be significantly reduced.

In particular, in the light guide plate according to claim 1, the color mixture region includes a parallel portion having a bottom surface parallel to the light emitting surface as the upper surface of the effective region, thereby impairing the light utilization efficiency of the tandem type surface light source device. In addition, it is possible to obtain a tandem surface light source device that mixes a plurality of monochromatic point light source arrays without unnecessarily increasing the thickness of the tandem surface light source device. In addition, a light guide plate structure is formed in a flat housing shape by using a plane provided in the vicinity of the light incident end face (particularly by making the bottom surface of the parallel part parallel to the upper surface (light emitting surface) of the effective region). The body can be placed and no L-shaped angle or corrugated structure is required.

According to the second aspect of the present invention, the predetermined inclination angle of the inclined upper surface of the inclined portion of the color mixture region is less than 30 °, and the entire thickness is formed on at least a part of the color mixture region. Since the angle is larger than the angle at which other light guide plates can be overlapped without increasing the height, the loss due to the inclined upper surface and the bottom surface of the inclined portion is suppressed to less than 10%, and the surface light source device Increase in thickness can be suppressed.

According to the third aspect of the present invention, even when light from a plurality of single-color point light sources is incident, the light from the plurality of single-color point light sources is mixed without reducing the light use efficiency. It becomes possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 6 is a diagram (plan view) showing a configuration example of the light guide plate according to the present invention. In FIG. 6, 1 is a plurality of monochromatic point light sources (1a is a red (R) point light source (eg, red LED), 1b is a green (G) point light source (eg, green LED), and 1c is blue (B ) Point light source (for example, a blue LED)), for example, emitting light having Lambertian directivity. Referring to FIG. 6, the light guide plate 3 receives light of a plurality of colors when entering the light from the light incident end surface 3a with a predetermined interval P in the length direction x of the light incident end surface 3a. A color mixing region 3f having a function of mixing light of a plurality of colors incident from the end surface 3a and an effective region 3e having a light emitting surface for emitting light from the color mixing region 3f on the upper surface are provided. Yes.

  Here, the length y of the mixed color region 3f is a plurality of monochromatic point light sources 1 (1a is a red (R) point light source, 1b is a green (G) point light source, and 1c is a blue (B) point light source). Is set to an optimum length necessary to prevent color unevenness.

  In the example of FIG. 6, a red (R) point light source 1 a, a green (G) point light source 1 b, and a blue (B) point light source 1 c are 1: 1: 1 as the plurality of monochromatic point light sources 1. However, even when the plurality of single-color point light sources 1 are configured as shown in FIG. 7, FIG. 8, FIG. 9, or the like, the configuration of the plurality of single-color point light sources 1 Accordingly, the light guide plate 3 of the present invention can be used in the same manner by setting the length y of the color mixture region 3f to an optimum length necessary to prevent color unevenness. Here, in the example of FIG. 7, the plurality of monochromatic point light sources 1 includes a red (R) point light source (for example, a red LED) 1 a, a green (G) point light source (for example, a green LED) 1 b, and a blue (B). A point light source (for example, a blue LED) 1c is repeatedly arranged at a ratio of 1: 2: 1. In the example of FIG. 8, the plurality of monochromatic point light sources 1 includes a red (R) point light source (for example, a red LED) 1 a, a green (G) point light source (for example, a green LED) 1 b, and a blue (B) point. The 3-in-1 package 8 in which the shape light source (for example, blue LED) 1c is arranged at a ratio of 1: 1: 1 is arranged with a constant interval W1. In the example of FIG. 9, the plurality of single-color point light sources 1 includes a red (R) point light source (for example, a red LED) 1 a, a green (G) point light source (for example, a green LED) 1 b, and a blue (B) point. The 4-in-1 package 9 in which the light source (for example, blue LED) 1c is arranged at a ratio of 1: 2: 1 is arranged with a constant interval W2.

  The light guide plate 3 (the mixed color region 3f and the effective region 3e) of the present invention is formed of the same material as the conventional light guide plate (for example, a resin such as PMMA and PC (polycarbonate), glass, or the like).

  Thus, in the present invention, the light guide plate 3 itself includes the color mixture region 3f (in other words, the light incident end surface 3a of the light guide plate 3 is extended to just before the light source 1, and the color mixture region is provided in the resin. (For example, the light incident end face 2a in FIG. 5 is extended toward the point light source 100 and the mixed color region is filled with resin or the like), so that the light from the plurality of monochromatic point light sources 1 is used. Even in the case of incident light, it is possible to mix light from a plurality of monochromatic point light sources 1 without reducing the light use efficiency.

  That is, for example, when the light incident end face 2a in FIG. 5 is extended toward the point light source 100 and the mixed color region is filled with resin or the like, of the light emitted from the point light source 100 toward the light guide plate, A light beam having a shallow incident angle at the light incident end face enters the light guide plate, and a light beam incident at an angle greater than the critical angle at the resin / air boundary in the color mixing region is totally reflected, and theoretically reaches the effective region without reflection loss. On the other hand, since light incident on the resin / air boundary of the color mixture region at an angle less than the critical angle leaks, a reflecting member is provided outside the color mixture region in order to return the light into the light guide plate. As a result, according to the simulation, the emission efficiency in the case of mixing colors in the resin increases from 21% to 73% compared to the case of mixing colors in the air. Thus, in the configuration of the present invention, even when light from a plurality of single-color point light sources 1 is incident, the light from the plurality of single-color point light sources 1 is mixed without degrading the light use efficiency. It turns out that it becomes possible.

  10 is a cross-sectional view of the light guide plate 3 according to the first embodiment of the present invention (for example, a cross-sectional view taken along the line CC in FIG. 6).

  Referring to FIG. 10, in the light guide plate 3 of the first embodiment, the effective area 3e decreases in thickness from the color mixing area 3f side toward the side opposite to the color mixing area 3f (anti-light-incident end face 3b). ing. That is, in the light guide plate 3 of the first embodiment, the bottom surface 3h of the effective region 3e is a surface inclined with respect to the top surface (light emitting surface) 3g of the effective region 3e.

  In the light guide plate 3 of the first embodiment, the color mixture region 3f has an upper surface 3c and a bottom surface 3d that are inclined with respect to the upper surface (light emitting surface) 3g of the effective region 3e. That is, in the light guide plate 3 of the first embodiment, the color mixture region 3f is a plate-like shape obtained by extending the bottom surface 3h of the effective region 3e as it is. Note that the inclination angle of the upper surface 3c and the bottom surface 3d of the effective color region 3e with respect to the upper surface (light emitting surface) 3g of the color mixing region 3f is less than 30 °, as in other forms described later, and the color mixing region 3f It is more than an angle at which another light guide plate 3 can be superimposed on at least a part of the region without increasing the overall thickness.

  FIG. 11 is a cross-sectional view of a surface light source illumination device (tandem type surface light source device) in which a plurality of light guide plates 3 of the first embodiment of FIG. In FIG. 11, the same reference numerals are given to the portions corresponding to FIG. 2. That is, in FIG. 11, the light guide plate 3 is shown as 21, 22, 23, and 24.

  In the first embodiment of the light guide plate 3 and the surface light source illumination device (tandem surface light source device) using the same, the light guide plate 3 is extended to the light source 1 side and the color mixture region 3f is provided in the light guide plate 3. The distance between the light source 1 and the light guide plate 3 can be made the shortest, whereby the light directly incident on the light guide plate 3 from the light source 1 can be maximized. Moreover, since it can be expected that many light beams are guided in the light guide plate 3 by total reflection with no reflection loss, the light utilization efficiency can be increased as compared with the case where the light is reflected by the reflecting member.

  By the way, in general, when light rays enter the light guide plate from the air, the emission angle from the air / light guide plate boundary is smaller than the incident angle to the air / light guide plate boundary (see FIG. 12). Accordingly, the directivity of the light source is narrower than the directivity in air in the light guide plate. For this reason, the length of the color mixture region 3f in the light guide plate is longer than the length of the color mixture region 212 (see FIGS. 3 and 4) disposed in the air.

  In the light guide plate 3 according to the first embodiment, the upper surface 3c and the bottom surface 3d of the color mixture region 3f are inclined with respect to the upper surface (light emitting surface) 3g of the effective region 3e. The thickness of the tandem type surface light source device is increased by an amount longer than the length of the color mixture region 212 arranged in the air.

  As the screen size increases, the number of light guide plates increases, and accordingly, the number of L-shaped angles increases and the number of members increases. In order to reduce the number of members, it is also conceivable to dispose a structure on a corrugated structural member integrated with an L-shaped angle. In particular, when an LED is used as a light source, it is conceivable that the casing is made of metal because of waste heat, but it is not easy to create a large corrugated structure by sheet metal processing.

  The light guide plate 3 of the second embodiment of the present invention has a structure capable of solving the above-described problems in the light guide plate 3 of the first embodiment.

  FIG. 13 is a cross-sectional view (for example, a cross-sectional view taken along the line CC of FIG. 6) of the light guide plate 3 according to the second embodiment of the present invention.

  Referring to FIG. 13, in the light guide plate 3 of the second embodiment, the effective region 3e does not change in thickness from the color mixture region 3f side toward the side opposite to the color mixture region 3f (counter-incident light end surface 3b). Or the thickness is reduced in part. In the example of FIG. 13, the effective area 3e is partially reduced in thickness from the color mixture area 3f side to the side opposite to the color mixture area 3f (the anti-incident light end face 3b). The thickness may be the same (same) from the color mixture region 3f side to the side opposite to the color mixture region 3f (counter-incident end surface 3b).

  In the example of FIG. 13, the color mixture region 3f of the light guide plate 3 includes a parallel portion 3m having an upper surface 3j and a bottom surface 3k parallel to the upper surface (light emitting surface) 3g of the effective region 3e, and a parallel portion 3m of the color mixture region 3f. And an effective region 3e, and an inclined portion 3t having an inclined upper surface 3r connecting the upper surface 3j of the parallel portion 3m and the upper surface 3g of the effective region 3e with a predetermined inclination angle with respect to the upper surface 3j and the bottom surface 3k of the parallel portion 3m. And. In the example of FIG. 13, the bottom surface 3s of the inclined portion 3t is parallel to the inclined upper surface 3r. That is, in the example of FIG. 13, the upper surface 3j and the bottom surface 3k of the parallel portion 3m are parallel to the upper surface (light emitting surface) 3g of the effective region 3e (therefore, the upper surface 3j and the bottom surface 3k of the parallel portion 3m are In addition, the inclined upper surface 3r and the bottom surface 3s of the inclined portion 3t are parallel to each other. Thereby, in the example of FIG. 13, the thickness of the light guide plate 3 does not change (same) in the color mixture region 3f of the light guide plate.

  Note that the inclination angle of the inclined portion 3t with respect to the inclined upper surface 3r and the parallel portion 3m of the bottom surface 3s with respect to the upper surface 3j and the bottom surface 3k (or the upper surface (light emitting surface) 3g of the effective region 3e) is less than 30 °, as will be described later. In this case, the angle may be more than an angle at which another light guide plate 3 can be superimposed on at least a part of the mixed color region 3f without increasing the overall thickness.

  FIG. 14 is a view showing a state in which a plurality of light guide plates 3 of FIG.

  FIG. 15 is a cross-sectional view of a surface light source illumination device (tandem surface light source device) in which a plurality of light guide plates 3 of FIG. In FIG. 15, the same reference numerals are given to the portions corresponding to those in FIG. That is, in FIG. 15, the light guide plate 3 is shown as 21, 22, 23, and 24.

  In the light guide plate 3 of the second form and the surface light source illumination device (tandem type surface light source device) using the same, the color mixture region 3f is provided in the light guide plate 3 as in the first form. 1 and the light guide plate 3 can be made the shortest distance, whereby the light directly incident on the light guide plate 3 from the light source 1 can be maximized. Moreover, since it can be expected that many light beams are guided in the light guide plate 3 by total reflection with no reflection loss, the light utilization efficiency can be increased as compared with the case where the light is reflected by the reflecting member.

  Further, in the light guide plate 3 of the second form, by providing the parallel part 3m in the color mixture area 3f, as shown in FIG. 16, when the color mixture area 3f is simply provided in the resin (in the first form) Compared to the light guide plate 3), the thickness of the surface light source device can be suppressed by the amount of the parallel portion 3m (compared to the light guide plate 3 of the first embodiment, the thickness is increased by the amount of the parallel portion 3m). Can be reduced).

  Furthermore, in the light guide plate 3 of the second embodiment, a portion parallel to the exit surface is provided on the light incident end surface 3a side (particularly, the bottom surface 3k of the parallel portion 3m is replaced with the upper surface (light exit surface) 3g of the effective region 3e). 14), the light guide plate structure can be arranged on the flat casing 300 as shown in FIG. 14, and there is an advantage that an L-shaped angle or a wave-shaped structure is not necessary.

  As described above, in the light guide plate 3 of FIG. 13, although the color mixture region is provided in the resin, the thickness of the surface light source device is not increased unnecessarily by simply extending the light guide plate, and emission from the light guide plate. The shape of the color mixture region 3f is determined so as not to reduce the efficiency. As a result, a tandem surface light source device that mixes a plurality of single-color point light source arrays without detracting from the light utilization efficiency of the tandem surface light source device and without unnecessarily increasing the thickness of the tandem surface light source device is obtained. be able to. Further, using a plane provided in the vicinity of the light incident end surface (by making the bottom surface 3k of the parallel part 3m parallel to the top surface (light emitting surface) 3g of the effective region 3e), the light is guided onto a flat housing. An optical plate structure can be arranged, and an L-shaped angle or a corrugated structure becomes unnecessary.

  That is, the light guide plate 3 of FIG. 13 has a tandem structure in which the anti-incident light end surface 3b is mounted on a step provided at the boundary between the exit surface of the adjacent light guide plate and the inclined upper surface of the color mixing region. Can be configured. And when the light-guide plate 3 of FIG. 13 comprises a tandem structure, as shown in FIG. 14, each light emission surface 3g is equipped with the shape where it connects flatly. Further, as shown in FIG. 14, the bottom surface of the effective area of the light guide plate 3 and the top surface of the color mixture area of the light guide plate 3 shown in FIG. Are overlapped without increasing the thickness, and the bottom surfaces of the mixed color regions of the respective light guide plates 3 are provided on a single plane. Thereby, the above-described excellent effect can be obtained.

  In the example of FIG. 13, the upper surface 3j and the bottom surface 3k of the parallel portion 3m are parallel to the upper surface (light emitting surface) 3g of the effective region 3e (therefore, the upper surface 3j and the bottom surface 3k of the parallel portion 3m are In addition, the inclined upper surface 3r and the bottom surface 3s of the inclined portion 3t are parallel to each other. Thus, in the example of FIG. 13, the thickness of the light guide plate 3 does not change (same) in the color mixture region 3 f of the light guide plate 3, but if necessary, the color mixture region 3 f of the light guide plate 3 enters the color mixture region 3 f. It is also possible to increase the thickness in the direction from the optical end face 3a toward the effective region 3e.

  In fact, as shown in FIG. 17A, the inventor of the present application has a tip thickness of 30 mm (the thickness of the light incident end surface is 1.5 mm, the thickness on the side opposite to the light incident end surface is 2.0 mm), Flat plate (incident end face thickness is 2.0 mm, anti-incident end face side thickness is 2.0 mm), tapered (incident end face thickness is 2.0 mm, anti-incident end face side thickness is 1) .5 mm) of three types of light guide plates as a mixed color region, a 0.33 mm square Lambertian light source was arranged from the light incident end face, and the amount of light reaching the counter light incident end face was simulated as the transmission efficiency. As a result, as shown in FIG. 17 (b), the transmission efficiency of the taper is 93.14% and the transmission efficiency of the flat plate is 93.11%, whereas the transmission efficiency of the taper is 86.44%. became. Accordingly, the shape of the color mixture region 3f is flat or when it is necessary to be bold, it is desirable to avoid the taper.

  Further, for example, in the example of FIG. 13, the inclination angle with respect to the upper surface 3j and the bottom surface 3k of the parallel portion 3m of the inclined portion 3t and the bottom surface 3s (or the upper surface (light emitting surface) 3g of the effective region 3e) increases. In addition, the transmission efficiency in the color mixture region decreases, that is, the reflection loss on the reflection surface covering the color mixture region leaked from the light guide plate increases.

  In fact, the inventor of the present application determines the inclination angle with respect to the inclined upper surface 3r of the inclined portion 3t and the upper surface 3j and the bottom surface 3k of the parallel portion 3m of the bottom surface 3s (or the upper surface (light emitting surface) 3g of the effective region 3e) and the light guide plate emission. An efficiency simulation was performed. FIG. 18 shows the simulation result.

  From FIG. 18, for example, in the example of FIG. 13, if the inclination angle is less than 30 degrees, the loss occurring at the inclined upper surface 3 r and the bottom surface 3 s of the inclined portion 3 t is reduced by about 10% compared to when the inclination angle is 0 degree. It is possible to suppress the increase in the thickness of the surface light source device while suppressing the emission efficiency at the light output end surface of the light guide plate from about 80% to 70%.

  As described above, the light guide plate 3 according to the present invention allows light of a plurality of colors to enter from the light incident end surface when entering the light from the light incident end surface at a predetermined interval in the length direction of the light incident end surface. It is characterized by comprising a color mixture region having a function of mixing light of a plurality of colors, and an effective region having a light emission surface on the upper surface for emitting light from the color mixture region.

  Here, the thickness of the effective region does not change from the color mixture region side to the side opposite to the color mixture region (counter-incident light end surface), or the thickness decreases in part.

  Further, the light guide plate of the present invention has a structure in which another light guide plate can be overlaid on at least a part of the color mixture region without increasing the overall thickness.

  As described above, the light guide plate 3 according to the present invention allows light of a plurality of colors to enter the light from the light incident end surface when entering the light from the light incident end surface at a predetermined interval in the length direction of the light incident end surface. Because it has a mixed color area that has the function of mixing multiple colors of light, even when entering light from multiple single-color point light sources, multiple single colors can be used without reducing the light utilization efficiency. It becomes possible to mix light from the point light source.

  In the light guide plate 3 of the present invention, the color mixture region includes a parallel portion having an upper surface and / or a bottom surface parallel to a light emitting surface as an upper surface of the effective region, a parallel portion of the color mixture region, and the effective region. And an inclined portion having an inclined upper surface connecting the upper surface of the parallel portion and the upper surface of the effective region with a predetermined inclination angle with respect to the upper surface and / or the bottom surface of the parallel portion. Yes.

  Here, the parallel part has the same or increased thickness as it goes from the light incident end face toward the inclined part. In addition, the thickness of the inclined portion is the same or increases from the parallel portion of the color mixture region toward the effective region.

  Thus, in the light guide plate 3 of the present invention, the color mixture region includes a parallel portion having a top surface and / or a bottom surface parallel to the light emitting surface as the top surface of the effective region. It is possible to obtain a tandem type surface light source device that mixes a plurality of monochromatic point light source arrays without impairing the light utilization efficiency of the device and without unnecessarily increasing the thickness of the tandem type surface light source device. In addition, a light guide plate structure is formed in a flat housing shape by using a plane provided in the vicinity of the light incident end face (particularly by making the bottom surface of the parallel part parallel to the upper surface (light emitting surface) of the effective region). The body can be placed and no L-shaped angle or corrugated structure is required.

  In the light guide plate 3 according to the present invention, the predetermined inclination angle of the inclined upper surface of the inclined portion of the color mixture region is less than 30 °, and the entire thickness is formed on at least a part of the color mixture region. It is characterized in that the angle is larger than the angle at which another light guide plate can be superimposed without increasing. Thereby, the increase in the thickness of the surface light source device can be suppressed while the loss due to the inclined upper surface and the bottom surface of the inclined portion is suppressed to less than 10%.

  The surface light source illumination device of the present invention is a surface light source using a plurality of light guide plate modules when one light guide plate and a light source for allowing predetermined light to enter the light guide plate are used as one light guide plate module. In the illumination device, the light guide plate of the present invention described above is used as the light guide plate, and each light guide plate is sequentially stacked in a manner in which the light guide plate of the previous stage is overlaid on at least a part of the mixed color region. It is characterized by being superposed on each other. Accordingly, even when light from a plurality of monochromatic point light sources is incident, illumination with high light use efficiency is possible.

  The surface light source illumination device of the present invention is characterized in that each light source of the plurality of light guide plate modules is mounted on a single substrate.

  That is, when the surface light source illumination device as shown in FIG. 2 is configured using the conventional light guide plate as shown in FIG. 1, as shown in an enlarged view (enlarged view of FIG. 2) in FIG. It is necessary to hold the light plates (21 to 24) at L-shaped angles (41 to 44) corresponding to the respective light plates (21 to 24), and the printed circuit boards on which the light sources (LEDs) 11 to 14 are mounted are as shown in 91 to 94. Since it is necessary to be arranged on the L-shaped angles 41 to 44 one by one, printed circuit boards 91 to 94 mounted with light sources (LEDs) 11 to 14 are required for each light guide plate (21 to 24). It becomes. As described above, in the surface light source illumination device as shown in FIG. 2, the substrates 91 to 94 on which the light sources (LEDs) 11 to 14 are mounted are surrounded by the light guide plates 21 to 24 and the L-shaped angles 41 to 44. Therefore, if the thickness is limited, an expensive flexible printed board must be used. Although a printed circuit board may be arranged between the light guide plates 21 to 24 and the L-shaped angles 41 to 44, a light source (LED) mounting substrate (light source driving substrate) is also required for each light guide plate.

  Further, if one printed circuit board is arranged between the bottom of the housing and the L-shaped angle, the light sources (LEDs) 11 to 14 are located on the L-shaped angle from notches (not shown) opened at the L-shaped angle. Therefore, it is difficult to mount so as to satisfy the height and inclination so as to face the light incident end face of the light guide plate.

  Thus, in the surface light source illumination device as shown in FIG. 2, a light source (LED) mounting substrate (light source driving substrate) on which a light source (LED) is mounted (drives the light source (LED)) is provided for each light guide plate. Since it is necessary, there is a problem that the number of members is increased. In particular, when a relatively expensive flexible printed circuit board is used, there is a problem that the cost is increased.

  On the other hand, in the surface light source illumination device of the present invention, each light source of the plurality of light guide plate modules is mounted on one substrate. Can be significantly reduced. In other words, since only one light source (LED) mounting substrate (light source driving substrate) is required for a plurality of light guide plate modules and a plurality of light sources (LEDs), the number of members is reduced compared to the conventional configuration. can do.

  Specifically, in the surface light source illumination device of the present invention, as shown in FIG. 20, one printed circuit board 9 on which light sources (LEDs) 11 to 14 are mounted at predetermined positions is arranged on the bottom of the casing, A plurality of light guide plates 21 to 24 can be arranged on one printed circuit board 9. The circuit components other than the light source (LED) may be mounted in a recess provided in the light guide plate structure, or the printed circuit board rear side using a notch (not shown) on the bottom surface of the housing. May be implemented. Further, connection to a power source and other necessary external circuits can be performed by wiring drawn from a notch (not shown) on the bottom surface of the housing.

  The light guide plate of the present invention described above can be manufactured by using a general molding method such as injection molding using a resin used for optical applications such as PMMA and PC, like a general light guide plate. Further, when productivity is not particularly questioned, it may be created by machining such as cutting from a resin plate or a glass plate.

  Further, in the above-described light guide plate of the present invention, the bottom surface and the side surface of the light guide plate may be covered with a reflecting member or the like, similarly to the conventional light guide plate. In addition, in the effective area of the light guide plate of the present invention described above, in the same manner as in the conventional light guide plate, on the bottom surface and / or the exit surface of the effective area, minute irregularities, cones, substantially hemispheres, trapezoidal dots, knurling, printing Processing for controlling the luminance distribution, which is so-called light extraction means, is performed by attaching dots or another sheet member coated with a diffuse reflection material. On the other hand, such diffuse reflection processing as the light extraction means is not necessary in the color mixture region. Further, in the light guide plate of the present invention described above, an optical member for a surface light source such as a diffuser plate, a diffuser sheet, or a prism sheet is provided on the light output surface of the light guide plate as necessary, as in the case of a conventional light guide plate. May be overlaid. Further, each light guide plate may be integrated, or may be divided if necessary.

  In addition, the light source of the surface light source illumination device of the present invention described above may be a linear light source such as CCFL or HCFL, or a point light source such as an LED that has been frequently used in recent years. Each light source is disposed close to the light incident end face of the light guide plate. When color mixing is necessary, color mixing is performed in a color mixing region provided on the light guide plate.

INDUSTRIAL APPLICABILITY The present invention can be used for a thin large surface light source device, in particular, a liquid crystal display backlight, a transmission signboard backlight, a lighting device for a trace table, a Schaukasten (X-ray light box) lighting device, a flat lighting device such as a ceiling lamp It is.

It is a perspective view of the conventional tandem type surface light source device (surface light source illumination device). It is sectional drawing of the surface light source device (surface light source illumination device) which has arrange | positioned the point light source row | line | column at sufficient distance for the light radiate | emitted from each point light source to spread and to be mixed in a light-incidence end surface. It is a figure which shows the light-guide plate used for the surface light source device (surface light source illumination device) of FIG. In the surface light source device (surface light source illumination device) of FIG. 2, it is a figure for demonstrating the color mixing in the space from each point light source to the light-incidence end surface of a light-guide plate. FIG. 5 is a diagram for explaining a problem of the configuration of FIGS. 2 to 4. It is a figure (plan view) showing an example of composition of a light guide plate concerning the present invention. It is a figure (top view) which shows the other structural example of a several monochromatic point light source. It is a figure (top view) which shows the other structural example of a several monochromatic point light source. It is a figure (top view) which shows the other structural example of a several monochromatic point light source. It is sectional drawing of the light-guide plate of the 1st form of this invention. It is sectional drawing of the surface light source illuminating device (tandem type | mold surface light source device) which overlap | superposed the tandem type using several light-guide plates of FIG. It is a figure for demonstrating that the outgoing angle from an air / light-guide plate boundary becomes small compared with the incident angle to the air / light-guide plate boundary generally when a light ray injects in the light-guide plate from the air. It is sectional drawing of the light-guide plate of the 2nd form of this invention. It is a figure which shows the state which piled up several light guide plates of FIG. It is sectional drawing of the surface light source illuminating device (tandem type | mold surface light source device) which overlap | superposed the tandem type using several light-guide plates of FIG. It is a figure for demonstrating that the light guide plate of a 2nd form can suppress the thickness increase of a surface light source device by the part which provided the parallel part compared with the light guide plate of a 1st form. It is a figure which shows the result of having simulated the amount of light reaching from the light incident end face to the counter light incident end face as a transmission efficiency, considering three types of light guide plates of a tip, a flat plate, and a taper as a mixed color region. It is a figure which shows the result of having performed the simulation of the inclination-angle of an inclination part, and light-guide plate emission efficiency. FIG. 3 is an enlarged view of FIG. 2. It is a figure which shows the example of arrangement | positioning of the printed circuit board in the surface light source illuminating device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 3 Light-guide plate 3a Light-incidence end surface 3e Effective area 3f Color mixing area 3g Upper surface (light emission surface) of effective area
3m Parallel portion 3j Upper surface of parallel portion 3k Bottom surface of parallel portion 3t Inclined portion 3r Upper surface of inclined portion 3s Bottom surface of inclined portion 9 Light source mounting substrate (light source driving substrate)

Claims (4)

When one light guide plate and a light source for allowing predetermined light to enter the light guide plate are one light guide plate module, a plurality of first light guide plate modules, second light guide plate modules, and third light guide plate modules. A surface light source illumination device using a piece,
The light guide plate of each light guide plate module is
When light of a plurality of colors is incident from the light incident end surface with a predetermined interval in the length direction of the light incident end surface, the light having a plurality of colors incident from the light incident end surface is mixed. A light guide plate comprising a mixed color region and an effective region having a light emitting surface for emitting light from the mixed color region on the upper surface,
The effective area of the light guide plate decreases from the color mixture area side toward the side opposite to the color mixture area (anti-light-incident end face), and the thickness on the counter-incident light end face side decreases. Part is provided ,
The color mixing region of the light guide plate has a structure in which another light guide plate can be superimposed on at least a part of the region without increasing the overall thickness, and the upper surface of the effective region. As a parallel part having a bottom surface parallel to the light exit surface, and between the parallel part of the color mixing region and the effective region, the parallel part has a predetermined inclination angle with respect to the upper surface and / or the bottom surface of the parallel part. An inclined portion having an inclined upper surface connecting the upper surface of the active region and the upper surface of the effective region,
The parallel part has the same or increased thickness as it goes from the light incident end face toward the inclined part,
The inclined portion has the same or increased thickness from the parallel portion of the color mixture region toward the effective region,
The surface light source illumination device is configured such that the light guide plate of the first light guide plate module and the light guide plate of the second light guide plate module are overlapped, and the light guide plate of the second light guide plate module and the third light guide plate module The light guide plates of other light guide plate modules are overlapped in a manner of overlapping the light guide plates of
The effective region where the thickness of the light guide plate of the first light guide plate module does not change is superimposed on the parallel portion in the color mixture region of the second light guide plate module,
On the inclined portion in the color mixture region of the second light guide plate module, a portion where the thickness of the first light guide plate module on the side opposite to the light incident end surface is reduced is superimposed,
The anti-incident light end face of the first light guide plate module is located at the boundary between the effective area of the light guide plate and the inclined portion of the second light guide plate module,
The effective area where the thickness of the light guide plate of the second light guide plate module does not change is superimposed on the parallel portion in the color mixture area of the third light guide plate module,
A portion where the thickness of the second light guide plate module on the light incident end face side is reduced is overlapped on the inclined portion in the color mixture region of the third light guide plate module;
The anti-incident light end face of the second light guide plate module is located at the boundary between the effective region of the light guide plate and the inclined portion of the third light guide plate module,
The light exit surface of the light guide plate of the first light guide plate module, the light exit surface of the light guide plate of the second light guide plate module, and the light exit surface of the light guide plate of the third light guide plate module are connected flat. And
The light source of the first light guide plate module, the light source of the second light guide plate module, and the light source of the third light guide plate module are mounted on one substrate,
The bottom surface of the parallel portion of the light guide plate of the first light guide plate module, the bottom surface of the parallel portion of the light guide plate of the second light guide plate module, and the bottom surface of the parallel portion of the light guide plate of the third light guide plate module. The light guide plate of the first light guide plate module, the light guide plate of the second light guide plate module, and the light guide plate of the third light guide plate module are arranged on a flat surface. Surface light source lighting device . The surface light source illumination device according to claim 1, wherein each of the light guide plates of the first light guide plate module, the second light guide plate module, and the third light guide plate module comprises:
The predetermined inclination angle of the inclined upper surface of the inclined portion of the color mixture region is less than 30 °,
A surface light source illumination device characterized in that the light source plate has an angle larger than an angle at which another light guide plate can be superimposed on at least a part of the color mixture region without increasing the overall thickness. . The surface light source illumination device according to claim 1 or 2, wherein each light source of the first light guide plate module, the second light guide plate module, and the third light guide plate module is:
A red point light source, a green point light source, and a blue point light source are repeatedly arranged at predetermined intervals in the length direction of the light incident end face of the light guide plate,
Alternatively, a package in which a red point light source, a green point light source, and a blue point light source are arranged at a predetermined ratio is arranged at a certain interval in the length direction of the light incident end face of the light guide plate. A surface light source illumination device. In the surface light source illumination device according to claim 3, each light guide plate of the first light guide plate module, the second light guide plate module, and the third light guide plate module is:
A surface light source , wherein the bottom surface and / or the exit surface of the effective area is subjected to luminance distribution control processing, and the color mixture region is not subjected to diffuse reflection processing as light extraction means Lighting device.

Images