WO2017179418A1 - Optical member, planar lighting device, and machining method - Google Patents

Abstract

According to an embodiment of the present invention, an optical member(2, 2A, 2B, 2C, 2D, 2E) has a base section (20, 20A, 20B, 20C, 20D, 20E) and prism sections (22, 22A, 22B, 22C, 22D). The base section (20, 20A, 20B, 20C, 20D, 20E) is a planarly formed transparent body. The prism sections (22, 22A, 22B, 22C, 22D) are formed on one surface of the base section (20, 20A, 20B, 20C, 20D, 20E), and are aligned in the predetermined direction. In a cross-section of each of the prism sections (22, 22A, 22B, 22C, 22D), said cross-section being in the predetermined direction, a second region (222, 222A, 222B) having a prism shape is continuous from a first region (221, 221A, 221B) having a tilt angle of 0-8 degrees with respect to a surface on the reverse side of the one surface, and the ratio of the first region with respect to the length in the predetermined direction is 60% or more but less than 100%.

Description

Optical member, planar illumination device, and processing method

The present invention relates to an optical member, a planar illumination device, and a processing method.

Conventionally, planar lighting devices used for high-mount stoplights of automobiles have been provided. In such a planar illumination device, for example, a light source, a mirror, and a lens may be used to facilitate light distribution control.

JP2015-179603A

However, in the conventional planar illumination device, the lens transmits light, but the back surface (back surface) of the light emitting surface cannot be seen through, and when a mirror is used, the mirror does not transmit light. Therefore, in the above-described conventional technology, it is possible to perform a desired light distribution control, but when the light source is not turned on, the back surface of the light emitting surface of the optical member can be seen through (hereinafter also referred to as “transparent”). There is a problem that it is difficult to maintain.

The present invention has been made in view of the above, and an object of the present invention is to provide an optical member, a planar illumination device, and a processing method capable of enabling desired light distribution control while maintaining transparency. And

In order to solve the above-described problems and achieve the object, an optical member according to an aspect of the present invention includes a base that is a transparent body formed in a flat plate shape, and is formed on one surface of the base and aligned in a predetermined direction. A second region having a prism shape is connected to a first region that is a prism portion and has an inclination angle with respect to the opposite surface of the one surface of 0 to 8 degrees in a cross section along the predetermined direction, and the predetermined region And a prism portion in which the ratio of the first region in the length in the direction is 60% or more and less than 100%.

According to one embodiment of the present invention, desired light distribution control can be achieved while maintaining transparency.

FIG. 1 is a front view showing a planar illumination device according to the embodiment. FIG. 2 is a side view showing the planar illumination device according to the embodiment. FIG. 3 is a side cross-sectional view illustrating a main part of the planar lighting device according to the embodiment. FIG. 4 is a side view showing an optical member having a low reflection portion and a luminance suppression portion according to the embodiment. FIG. 5 is a side view showing the planar illumination device according to the first modification. FIG. 6 is a diagram illustrating a change due to lighting of the light source of the planar illumination device according to the first modification. FIG. 7 is a side cross-sectional view showing the main part of the optical member according to Modification 2. FIG. 8 is a side cross-sectional view showing a main part of an optical member according to Modification 3. FIG. 9 is a side view showing a planar illumination device according to Modification 4. FIG. 10 is a front view showing a planar lighting device according to Modification 5. FIG. 11 is a side view showing a planar lighting device according to Modification 5. FIG. 12 is a front view showing a main part of a planar lighting device according to Modification 6.

Hereinafter, the planar illumination device having the optical member according to the embodiment will be described with reference to the drawings. The application of the optical member is not limited by the embodiments described below. It should be noted that the drawings are schematic, and the relationship between the dimensions of each element, the ratio of each element, and the like may differ from the actual situation. Even between the drawings, there are cases in which portions having different dimensional relationships and ratios are included.

As described above, an object of the present embodiment is to provide an optical member, a planar illumination device, and a processing method capable of enabling desired light distribution control while maintaining transparency. Here, in the present embodiment, a planar illumination device is further provided that emits desired light to the light extraction surface side of the optical member and can suppress an increase in light leaking to the back surface side of the optical member. Also aimed.

For example, in a planar illumination device using a mirror, desired light distribution control can be performed, but light is not transmitted to the back side of the light emitting surface (light extraction surface) by the mirror. Therefore, a planar illumination device that transmits light in a direction intersecting the light emitting surface is desired in order to improve visibility and the like when the planar illumination device is used in a high-mount stoplight of an automobile or the like. However, in a planar illumination device that transmits light in a direction intersecting the light emitting surface, it is possible to emit desired light to the light emitting surface side of the optical member and suppress an increase in light leaking to the back surface side of the light extraction surface. There is a problem that it is difficult. Therefore, an object of the present embodiment is to provide a planar illumination device that emits desired light to the light extraction surface side of the optical member and can suppress an increase in light leaking to the back surface side of the optical member. .

Specifically, in order to solve the above-described problems and achieve the object, the planar lighting device according to one aspect of the present embodiment is a back surface of the light extraction surface of the base that is a transparent body formed in a flat plate shape. A light source part disposed along one side surface of the base part of the optical member, and a ratio of luminance of the light extraction surface to luminance of the back surface The luminance ratio is 20 or more. According to this aspect, desired light can be emitted to the light extraction surface side of the optical member, and an increase in light leaking to the back surface side of the optical member can be suppressed.

(Embodiment)
First, the outline | summary of a structure of the planar illuminating device 1 is demonstrated using FIG.1 and FIG.2. FIG. 1 is a front view showing a planar illumination device according to the embodiment. FIG. 2 is a side view showing the planar illumination device according to the embodiment.

As shown in FIG. 1, the planar illumination device 1 includes an optical member 2 and a light source unit 3.

The optical member 2 has a base 20 that is a transparent body formed in a flat plate shape. For example, the base portion 20 is formed of a light transmissive material. For example, the base 20 may be formed of acrylic resin, polycarbonate, or the like. For example, the base 20 may be a so-called light guide plate. The base 20 may be formed of any material as long as it has desired translucency (for example, it is transparent), desired strength, heat resistance, and the like. Further, in the optical member 2, one surface 21 (hereinafter also referred to as “light extraction surface 21”) illustrated in FIG. 1 is a light emitting surface. In addition, the desired translucency here may be that the back surface (back surface) of the light extraction surface 21 that is a light emitting surface is seen through, that is, transparent.

Further, as shown in FIG. 2, the base portion 20 of the optical member 2 is formed with a prism portion 22 on one side in the thickness direction of the base portion 20. For example, the prism portion 22 is formed on the back surface (hereinafter also referred to as “back surface”) of the light extraction surface 21 of the optical member 2. The prism portions 22 are formed side by side in a predetermined direction. For example, the prism portion 22 is formed side by side in the longitudinal direction of the base portion 20 (left-right direction in FIG. 2).

Here, the prism portion 22 will be described with reference to FIG. FIG. 3 is a side cross-sectional view illustrating a main part of the planar lighting device according to the embodiment. The prism portion 22 is formed in a shape having a predetermined prism function. In addition, the prism portion 22 has a prism shape in the first region 221 in which the inclination angle θ1 with respect to the plane in which the thickness direction of the base portion 20 is orthogonal in the cross section along the longitudinal direction of the base portion 20 is 0 degree (°) or more and 8 degrees or less. The 2nd area | region 222 which has is continuous. In the following description, the first region 221 of one prism portion 22 continues to the height of the first region 221 of one prism portion 22, that is, the second region 222 of another prism portion 22. The height of the position is defined as “first height”. In addition, the height of the position where the first region 221 and the second region 222 of one prism portion 22 are continuous is referred to as a “second height”.

The prism portion 22 may be formed along the width direction of the base portion 20 (hereinafter, also referred to as “short direction”), or may be formed inclined with respect to the short direction of the base portion 20. . For example, the first region 221 of the prism portion 22 may be formed along the short direction of the base portion 20. Further, for example, the second region 222 of the prism portion 22 may be formed along the short direction of the base portion 20. In the example shown in FIG. 3, the light extraction surface 21 is a flat surface and the thickness direction of the base portion 20 is perpendicular to the surface. Therefore, the surface where the thickness direction of the base portion 20 is orthogonal will be described as the light extraction surface 21 hereinafter. .

For example, in FIG. 3, in the prism portion 22, as shown in FIG. 3, the first tilt angle θ <b> 1 with respect to the light extraction surface 21 in the section along the longitudinal direction of the base portion 20 is 0 degree (°) or more and 8 degrees or less. A second region 222 having a prism shape is continuous with the region 221. Further, it is more preferable that the inclination angle θ1 of the first region 221 of the prism portion 22 is not less than 0 degrees and not more than 4 degrees. Further, as shown in FIG. 3, the second region 222 of one prism portion 22 is continuous with the first region 221 of another prism portion 22.

As shown in FIG. 3, for example, in the optical member 2, in the cross section along the longitudinal direction of the base portion 20, the first region 221 of one prism portion 22 is in one direction (a direction away from the light extraction surface 21). The second region 222 of one prism portion 22 has an inclined shape, and one end of the second region 222 is continuous with the first region 221, and is opposite to one direction with respect to the light extraction surface 21 (with respect to the light extraction surface 21. The other end portion is continuous with the first region 221 of the other prism portion 22. For example, in the cross section along the longitudinal direction of the base portion 20, the first region 221 of one prism portion 22 has a shape that inclines in a direction away from the light extraction surface 21 from the left to the right in FIG. The second region 222 of one prism portion 22 has a shape in which one end portion is continuous with the first region 221 and is inclined in a direction approaching the light extraction surface 21 from left to right in FIG. The other end portion is continuous with the first region 221 of the other prism portion 22.

Further, for example, in the cross section along the longitudinal direction of the base portion 20, the first region 221 of one prism portion 22 extends from a first height in the thickness direction of the base portion 20 to a second height higher than the first height. Has a shape. The second region 222 of one prism portion 22 has a shape in which one end portion is continuous with the first region 221 at the second height and extends to the first height, and the other end at the first height. The portion is continuous with the first region 221 of the other prism portion 22. For example, the second region 222 of the leftmost prism portion 22 in FIG. 3 is continuous with the first region 221 of the adjacent (right) prism portion 22. In addition, the inclination angle with respect to the light extraction surface 21 of the second region 222 in the cross section along the longitudinal direction of the base 20 may be appropriately set according to a desired light distribution.

In the prism portion 22, the ratio R11 of the first region 221 in the length of the base portion 20 in the longitudinal direction is 60% or more and less than 100%. As shown in FIG. 3, the length L11 of the first region 221 in the length in the longitudinal direction of the base 20 is the length L10 of the entire prism portion 22 in the length in the longitudinal direction of the base 20 (hereinafter referred to as “structural unit length”). R11 ”) is 60% or more and less than 100%. For example, the ratio R11 described above is calculated by the following mathematical formula (1).

Ratio R11 = length L11 of first region 221 / constituent unit length L10 (1)

For example, the structural unit length L10 corresponds to the total length of the first region 221 and the second region 222 in the length of the base 20 in the longitudinal direction. In the prism portion 22, the ratio R11 of the first region 221 in the length of the base portion 20 in the longitudinal direction is more preferably 75% or more and less than 100%.

The prism portion 22 is formed so that the structural unit length L10 of the prism portion 22 is 40 μm or more and 500 μm or less. The prism unit 22 more preferably has a structural unit length L10 of the prism unit 22 of not less than 80 μm and not more than 250 μm. With the above-described configuration, the optical member 2 has a desired light-transmitting property (for example, is transparent) even in the base portion 20 on which the prism portion 22 is formed. For example, with the configuration described above, the optical member 2 is transparent, and when the light source unit 3 is in a non-lighting state, the back side can be seen through from the light extraction surface 21 side of the base 20, and from the back side of the base 20. The light extraction surface 21 side can be seen through.

Further, the plurality of prism portions 22 may be formed symmetrically (symmetric in FIG. 2) with respect to a center line passing through the central portion in the longitudinal direction on the back surface of the light extraction surface 21 of the optical member 2. For example, on the back surface of the light extraction surface 21 of the optical member 2, a plurality of prism portions 22 are arranged in the order of the first region 221 and the second region 222 from the side surface 23 on the left side in FIG. 2 to the central portion in the longitudinal direction. . Further, for example, on the back surface of the light extraction surface 21 of the optical member 2, the prism portion 22 arranged in the order of the first region 221 and the second region 222 from the right side surface 24 side in FIG. Multiple lines. As described above, the plurality of prism portions 22 may be formed mirror-symmetrically with respect to the center line in the longitudinal direction on the back surface of the light extraction surface 21 of the optical member 2.

The light source unit 3 includes a holding member 30, a light source 31 such as an LED (Light Emitting Diode), and a light incident element 32. The light source unit 3 is disposed along the side surfaces 23 and 24 of the base 20 of the optical member 2. For example, the light source unit 3 is provided as a pair at both ends of the optical member 2. In addition, the light source part 3 may be provided in only one of the both end parts of the optical member 2.

For example, the pair of holding members 30 hold the optical member 2 from both sides. In FIG. 1, a pair of light sources 3 is provided at both ends of the optical member 2 in the longitudinal direction of the base 20 and holds the optical member 2. Each holding member 30 holds the light source 31 and the light incident element 32. 1 illustrates a state in which the light source 31 and the light incident element 32 are exposed in a front view. However, if the light source 31 and the light incident element 32 are disposed at predetermined positions with respect to the optical member 2, for example, The cover member 30 may be covered. The optical member 2 may be held by the holding member 30 by covering the vicinity of the side surfaces 23 and 24 with the holding member 30.

Each light source unit 3 is provided with a plurality (four in FIG. 1) of light sources 31. For example, the plurality of light sources 31 are provided side by side in a predetermined direction. In FIG. 1, the light source unit 3 is provided side by side along the short direction of the base 20.

For example, the light incident element 32 has a function of converting light emitted from the light source 31 that is a point light source into light of a linear light source. For example, the light incident element 32 is formed of a light transmissive material. The light incident element 32 is provided between the light source 31 and the side surfaces 23 and 24 of the base 20. For example, in the light source unit 3 on the left side in FIG. 1, the light incident element 32 is provided between the light source 31 and the side surface 23 of the base 20. Further, in the light source unit 3 on the left side in FIG. 1, the light incident element 32 is provided along the side surface 23 of the base 20. Further, for example, in the light source unit 3 on the right side in FIG. 1, the light incident element 32 is provided between the light source 31 and the side surface 24 of the base 20. Further, in the light source unit 3 on the right side in FIG. 1, the light incident element 32 is provided along the side surface 24 of the base 20.

Further, a mechanism for performing predetermined optical control is provided on the surface 321 on the light source 31 side of the light incident element 32 (hereinafter also referred to as “light incident surface 321”). For example, the light incident surface 321 on the light source 31 side of the light incident element 32 may be a TIR (Total Internal Reflection) -Fresnel lens surface. The light incident surface 321 of the light incident element 32 is provided with a mechanism for performing predetermined optical control at a location corresponding to each light source 31. 1 schematically illustrates the case where one light incident element 32 is used for the four light sources 31, but the light incident elements 32 may be provided for each light source 31, respectively. The light incident element 32 may have any configuration as long as desired light distribution control is possible.

In addition, it is desirable that the luminance of the surface of the light incident element 32 facing the side surfaces 23 and 24 of the base 20, that is, the surface 322 opposite to the light incident surface 321 of the light incident element 32 is uniform. For example, it is desirable that the luminance in the vertical direction of the surface of the light incident element 32 that faces the side surfaces 23 and 24 of the base 20 is uniform. A predetermined light distribution member may be provided on the surface of the light incident element 32 that faces the side surfaces 23 and 24 of the base 20. For example, a lenticular lens, a diffusing element, a prism, or a TIR-Fresnel lens may be provided as a light distribution member on the surface of the light incident element 32 that faces the side surfaces 23 and 24 of the base 20. In addition, although a light distribution member may be arrange | positioned to the side surfaces 23 and 24 of the base 20, it is desirable that the brightness | luminance after transmitting the side surfaces 23 and 24 is uniform in this case. The light incident element 32 may be continuous with the side surfaces 23 and 24 of the base 20. For example, the light incident element 32 may be integrally formed with the base 20. Also, a mechanism for performing predetermined optical control may be provided on the opposite surface 322 side of the light incident element 32. For example, an optical element such as a TIR-Fresnel lens or lenticular may be disposed on the opposite surface 322 of the light incident element 32.

In addition, it is desirable that the width W11 of the region where the luminance is uniform in the light incident element 32 is equal to or greater than the width W10 of the base 20 in the short direction. Here, the term “uniform brightness” means, for example, that a brightness ratio between a bright part and a dark part (dark part brightness / bright part brightness) described later is 70% or more, preferably 80% or more. Thereby, since the planar illumination device 1 is irradiated with light from the light incident element 32 over the entire lateral direction of the side surfaces 23 and 24 of the optical member 2, the light extraction surface 21 of the base 20 is more evenly distributed. Can emit light. The light incident element 32 may have the same thickness as the base 20. In the example shown in FIG. 1, for simplicity of explanation, the case where the width W11 of the region where the luminance is uniform in the light incident element 32 is the same as the width of the light incident element 32 is illustrated. The width W11 of the region where the luminance is uniform in the optical element 32 may be narrower than the width of the light incident element 32.

For example, in the front luminance of the light emitting area (light extraction surface 21), that is, the luminance in the vertical direction of the light extraction surface 21, the luminance distribution is focused on the light incident end surfaces (side surfaces 23 and 24) of the light guide plate (base 20). In the state, the luminance distribution (averaged in the thickness direction) is calculated at a pitch of at least 1 mm, preferably 0.5 mm, in the width direction (short direction) of the light guide plate. Further, for example, by setting the width W11 of the region where the luminance is uniform in the light incident element 32 to be equal to or larger than the width W10 in the short direction of the base portion 20, the bright portion and the dark portion of the luminance obtained by the calculation method described above are used. The luminance ratio (dark portion luminance / bright portion luminance) can be 70% or more, preferably 80% or more. Further, for example, the pitch of the optical elements of the linear light source (the light incident surface 321 of the light incident element 32) is more preferably 10 to 1000 μm. Further, for example, the pitch of the optical elements of the linear light source (the light incident surface 321 of the light incident element 32) is more preferably 20 to 200 μm.

Moreover, the optical member 2 of the surface illumination device 1 may have various configurations in order to perform desired light distribution control. This point will be described with reference to FIG. FIG. 4 is a side view showing an optical member having a low reflection portion and a luminance suppression portion according to the embodiment. As shown in FIG. 4, the optical member 2 may include a low reflection portion 25 and a luminance suppression portion 26.

As shown in FIG. 4, the low reflection part 25 which suppresses the reflection in the base 20 is provided in the optical extraction surface 21 side of the base 20 in the optical member 2. As shown in FIG. For example, the optical member 2 is formed with a low reflection portion 25 having a low reflection function so as to overlap the light extraction surface 21. For example, the low reflection portion 25 may have a fine uneven shape of 1 μm or less such as a dielectric multilayer film formed by sputtering or vapor deposition or a moth-eye shape. For example, the low reflection part 25 may be formed by performing the low reflection process on the light extraction surface 21. For example, in the low reflection process, it is preferable to process the light extraction surface 21 into a mirror surface state. For example, the above-described processing methods include direct processing (sputtering, vapor deposition, shaping, etc.) on the base 20 as a light guide plate, insert molding of a low reflection film, and application of a low reflection film via an adhesive or adhesive. Any processing method such as combination may be used.

The regular reflectance of the light extraction surface 21 is preferably 1.6% or less. For example, when the regular reflectance of the light extraction surface 21 is 1.6% or less, in the example illustrated in FIG. 4, the ratio of the light beam IL14 reflected in the base 20 out of the light beams IL12 toward the light extraction surface 21 is 1. .. 6% (= light amount of IL14 / light amount of IL12 * 100) or less. Further, for example, the regular reflectance of the light extraction surface 21 may be 1.6% or less by forming the low reflection portion 25 so as to overlap the light extraction surface 21 of the optical member 2. In addition, the regular reflectance of the light extraction surface 21 is further preferably 0.8% or less. In addition, the regular reflectance of the light extraction surface 21 is further preferably 0.4% or less.

In addition, formation of the low reflection part 25 mentioned above is an example, and the optical member 2 may be any configuration as long as the regular reflectance of the light extraction surface 21 satisfies a desired value. For example, if the regular reflectance of the light extraction surface 21 satisfies a desired value, the optical member 2 may not have the low reflection portion 25.

As shown in FIG. 4, a luminance suppression unit 26 that suppresses the emission of light to the back side is provided on the back side of the base 20 in the optical member 2. For example, the optical member 2 is formed with a luminance suppressing portion 26 that suppresses light emission to the back surface side so as to cover the back surface. For example, the luminance suppression unit 26 may be a louver film, a film that reflects the wavelength of light from a light source (dielectric multilayer film), a film that absorbs light (dielectric multilayer film), a transparent film containing a dye-based pigment, or the like. Good. In addition, it is preferable to use a louver film to shield light emitted in an oblique direction. Note that the luminance suppressing unit 26 may have any configuration as long as it has a desired function.

It is preferable that the luminance ratio LR1 that is the ratio of the luminance of the light extraction surface 21 to the luminance of the back surface is 20 or more. For example, the luminance ratio LR1 is calculated by the following mathematical formula (2).

Luminosity ratio LR1 = luminance of light extraction surface 21 / luminance of back surface (2)

For example, the luminance ratio LR1 may be 20 or more by arranging the luminance suppressing unit 26 on the back side of the base 20. Further, it is preferable that the luminance ratio LR1 is 40 or more. Further, it is more preferable that the luminance ratio LR1 is 100 or more. For example, the luminance of the light extraction surface 21 may be the luminance in the vertical direction of the light extraction surface 21. Further, the luminance on the back surface may be the luminance in the thickness direction of the base portion 20 on the back surface of the light extraction surface 21 (surface on which the prism portion 22 is formed). For example, the luminance ratio LR1 may be a ratio of the front luminance on the light extraction surface 21 side to the front luminance on the back surface side.

The arrangement of the luminance suppressing unit 26 described above is an example, and the optical member 2 may have any configuration as long as the luminance ratio LR1 satisfies a desired value. For example, if the luminance ratio LR1 satisfies a desired value, the optical member 2 may not have the luminance suppressing unit 26.

Here, the light distribution in the optical member 2 will be described using the light beams IL11 to IL15 shown in FIG. Light rays IL11 to IL15 shown in FIG. 4 virtually indicate the light distribution in the optical member 2. For example, among the light beams IL11 that travel from the base 20 toward the second region 222, some of the light beams IL12 are reflected in the direction of the light extraction surface 21 by the second region 222 having a prism function.

Of the light beams IL12 that travel from the base 20 toward the light extraction surface 21, some of the light beams IL13 are emitted to the outside of the light extraction surface 21. For example, since the regular reflectance of the light extraction surface 21 satisfies a desired value due to suppression of reflection by the low reflection portion 25, most of the light beam IL13 is radiated out of the light extraction surface 21. The Thus, the planar illumination device 1 can suppress an increase in the amount of light reflected from the light extraction surface 21 side into the base 20 when the regular reflectance of the light extraction surface 21 satisfies a desired value. The light extraction efficiency can be improved.

In addition, a part of the light beam IL14 out of the light beam IL12 from the base 20 toward the light extraction surface 21 is reflected by the light extraction surface 21. For example, since the reflection is suppressed by the low reflection portion 25, a small amount of the light beam IL14 out of the light beam IL12 is reflected by the light extraction surface 21. As described above, the optical member 2 is able to reduce the light leaking from the back surface by suppressing reflection on the light emitting surface (light extraction surface 21).

Further, for example, among the light beams IL11 that travel from the inside of the base portion 20 toward the second region 222, some of the light beams IL15 pass through the second region 222 and are emitted to the outside of the base portion 20. That is, the light beam IL15 becomes light that leaks in an oblique direction from the back surface when it is virtually planar. Such light leaking from the back surface may be visually recognized by a person on the back surface side, for example, a person inside or outside the vehicle in which the planar lighting device 1 is used as a high-mount light. However, in the planar lighting device 1, the luminance ratio LR <b> 1 satisfies a desired value by the luminance suppressing unit 26 or the like, so that light leaking to the back side is suppressed and the influence on the person on the back side can be suppressed. .

(Modification 1-6)
A planar irradiation apparatus according to a modification of the embodiment will be described with reference to the drawings. In addition, about the structure similar to embodiment, the code | symbol same as embodiment is attached | subjected and description is abbreviate | omitted suitably.

(Modification 1)
First, the planar lighting device 100 according to the first modification will be described with reference to FIGS. 5 and 6. FIG. 5 is a side view showing the planar illumination device according to the first modification. FIG. 6 is a diagram illustrating a change due to lighting of the light source of the planar illumination device according to the first modification.

As shown in FIG. 5, the planar illumination device 100 includes an optical member 200 and a light source unit 3.

The optical member 200 has a base 201 that is a transparent body formed in a flat plate shape. For example, the base 201 is formed of a light-transmitting material like the base 20 of the optical member 2. Further, in the optical member 200, a prism region 202 to be subjected to prism processing is formed on the back surface of the light emitting surface (the upper surface in FIG. 5) of the optical member 200. For example, the prism region 202 is formed by arranging prism structures in the longitudinal direction of the base 201 (left and right direction in FIG. 5). For example, the prism region 202 is formed by arranging a plurality of prism portions 22 as shown in FIG. 3 in a predetermined direction.

Further, in the example shown in FIG. 5, non-prism regions 203 that are not subjected to prism processing are formed at both ends of the base 201 in the longitudinal direction (left-right direction in FIG. 5). Note that the length of the non-prism region 203 may be appropriately set according to the application of the planar illumination device 100 or the like.

Here, a processing method for forming the prism region 202 and the non-prism region 203 will be described.

For example, in the optical member 200, a prism region 202 in which a prism processing is performed on a predetermined region on the back surface of the base 201 may be formed by post processing as a processing method for performing prism processing. Thereby, in the optical member 200, a prism area 202 is formed by applying a prism process to a predetermined area on the back surface of the base 201, and a non-prism area 203 is formed in another area.

Further, for example, after the optical member 200 is subjected to prism processing over the entire back surface of the base 201, the non-prism region 203 is formed by removing the prism processing in the region corresponding to the non-prism region 203 by post-processing. It may be formed. Thereby, in the optical member 200, a prism area 202 is formed by applying a prism process to a predetermined area on the back surface of the base 201, and a non-prism area 203 is formed in another area.

Further, for example, the optical member 200 forms the prism region 202 by post-processing after the region corresponding to the non-prism region 203 is generated on the back surface of the base 201 lower than the height of the region subjected to the prism processing. Accordingly, the prism region 202 may be formed. Thereby, in the optical member 200, a prism area 202 is formed by applying a prism process to a predetermined area on the back surface of the base 201, and a non-prism area 203 is formed in another area.

The processing method for forming the prism region 202 and the non-prism region 203 is not limited to the above, and any processing method can be used as long as the prism region 202 and the non-prism region 203 can be formed in a desired region. There may be. For example, the optical member 200 may be molded by the above processing method using a predetermined mold.

Next, the non-lighting state and the lighting state of the planar lighting device 100 will be described with reference to FIG.
A planar lighting device 100-1 illustrated in FIG. 6 represents the planar lighting device 100 in a non-lighting state, and a planar lighting device 100-2 represents the planar lighting device 100 in a lighting state. The planar illumination devices 100-1 and 100-2 are referred to as the planar illumination device 100 when not distinguished from each other. The planar illumination device 100 shown in FIG. 6 shows a case where the planar illumination device 100 is viewed from the front.

As shown in FIG. 6, in the planar lighting device 100-1 in the non-lighted state, the entire base 201 of the optical member 200 is transparent, and an object located behind can be visually recognized. That is, in the planar lighting device 100-1 in the non-lighting state, the member located behind in both the prism region 202 subjected to the prism processing and the non-prism region 203 not subjected to the prism processing. Is visible. Further, in the planar lighting device 100-1 in the non-lighting state, when viewed from the back of the planar lighting device 100, the entire base portion 201 of the optical member 200 is transparent, and an object positioned in the front is also the same. It may be visible.

On the other hand, as shown in FIG. 6, in the planar lighting device 100-2 in the lighting state, the prism region 202 of the base 201 of the optical member 200 emits light, and the member located behind cannot be visually recognized. Further, in the planar lighting device 100-2 in the lighting state, since the non-prism region 203 of the base 201 of the optical member 200 does not emit light, the member located behind can be visually recognized. As described above, the planar illumination device 100 forms the prism region 202 and the non-prism region 203 in an appropriate region, thereby performing surface light emission using a desired region, and the other regions are desired even in a lighting state. Light transmittance can be maintained.

(Modification 2)
Next, an optical member 2A according to Modification 2 will be described with reference to FIG. FIG. 7 is a side cross-sectional view showing the main part of the optical member according to Modification 2.

The optical member 2A has a base 20A that is a transparent body formed in a flat plate shape. For example, the base 20 </ b> A is formed of a light-transmitting material like the base 20 of the optical member 2. A prism portion 22A is formed on the back surface of the light extraction surface 21A of the optical member 2A. The prism portion 22A is formed side by side in a predetermined direction. For example, the prism portion 22A is formed side by side in the longitudinal direction of the base portion 20A (the left-right direction in FIG. 7).

The prism portion 22A is formed in a shape having a predetermined prism function. For example, in the prism portion 22A, the second region 222A having a prism shape is continuous with the first region 221A parallel to the light extraction surface 21A in the cross section along the longitudinal direction of the base portion 20A. In FIG. 7, the first region 221A is formed to be parallel to the light extraction surface 21A, that is, to have an inclination angle of 0 degree, but in the cross section along the longitudinal direction of the base 20A, the first region 221A is formed with respect to the light extraction surface 21A. The inclination angle may be 0 degree or more and 8 degrees or less. In addition, it is more preferable that the inclination angle of the first region 221A of the prism portion 22A is not less than 0 degrees and not more than 4 degrees.

The second region 222A of the prism portion 22A is formed in a shape protruding from the back surface. For example, the second region 222A is formed in a triangular shape that protrudes from the back surface to the outside in a cross section along the longitudinal direction of the base portion 20A.

In the prism portion 22A, the ratio R21 of the first region 221A in the length of the base portion 20A in the longitudinal direction is the same as the ratio R11 in the prism portion 22. For example, the length L21 of the first region 221A in the length in the longitudinal direction of the base portion 20A is the length L20 of the entire prism portion 22A in the length in the longitudinal direction of the base portion 20A (hereinafter also referred to as “structural unit length L20”). It is preferable that the ratio R21 to is 60% or more and less than 100%. In the prism portion 22A, the ratio R21 is more preferably 75% or more and less than 100%.

The prism portion 22A is formed so that the structural unit length L20 of the prism portion 22A is 40 μm or more and 500 μm or less. The prism unit 22A more preferably has a structural unit length L20 of the prism unit 22A of not less than 80 μm and not more than 250 μm. With the above-described configuration, the optical member 2A has a desired translucency (for example, is transparent) even in the base portion 20A where the prism portion 22A is formed.

Here, the light distribution in the optical member 2A will be described using the light beams IL21 to IL28 shown in FIG. Note that the light beams IL21 to IL28 shown in FIG. 7 virtually indicate the light distribution in the optical member 2A. For example, among the light beams IL21 traveling from the base 20A toward the second region 222A, a part of the light beams IL22 is reflected in the direction of the light extraction surface 21A by the second region 222A having a prism function.

Of the light beam IL22 that travels from the inside of the base 20A toward the light extraction surface 21A, a part of the light beam IL23 is emitted outside the light extraction surface 21A. Further, out of the light beam IL22 from the base 20A toward the light extraction surface 21A, a part of the light beam IL24 is reflected by the light extraction surface 21A and emitted to the back surface side of the base 20A.

Further, for example, of the light beam IL21 that travels from the inside of the base portion 20A toward the second region 222A, a part of the light beam IL25 passes through the second region 222A and is radiated out of the base portion 20A, and is reflected by the adjacent second region 222A. Then, the light beam IL26 is emitted to the back surface side of the base portion 20A. Further, for example, the light beam IL27 traveling from the inside of the base portion 20A toward the second region 222A passes through the second region 222A and is radiated to the back surface side of the base portion 20A as the light beam IL28. As described above, in the optical member 2A, it is difficult to suppress the light emitted to the back surface side of the base portion 20A than the optical member 2 according to the embodiment. The member 2 is more preferable than the optical member 2A.

(Modification 3)
Next, an optical member 2B according to Modification 3 will be described with reference to FIG. FIG. 8 is a side cross-sectional view showing a main part of an optical member according to Modification 3.

The optical member 2B has a base portion 20B which is a transparent body formed in a flat plate shape. For example, the base portion 20 </ b> B is formed of a light transmissive material like the base portion 20 of the optical member 2. A prism portion 22B is formed on the back surface of the light extraction surface 21B of the optical member 2B. The prism portions 22B are formed side by side in a predetermined direction. For example, the prism portion 22B is formed side by side in the longitudinal direction of the base portion 20B (the left-right direction in FIG. 8).

The prism portion 22B is formed in a shape having a predetermined prism function. For example, in the prism portion 22B, a second region 222B having a prism shape is continuous with the first region 221B parallel to the light extraction surface 21B in the cross section along the longitudinal direction of the base portion 20B. In FIG. 8, the first region 221B is formed so as to be parallel to the light extraction surface 21B, that is, to have an inclination angle of 0 degree, but in the cross section along the longitudinal direction of the base 20B, the first region 221B is formed with respect to the light extraction surface 21B. The inclination angle may be 0 degree or more and 8 degrees or less. Further, it is more preferable that the inclination angle of the first region 221B of the prism portion 22B is 0 degree or more and 4 degrees or less. Depending on the processing accuracy, the inclination angle of the first region 221B of the prism portion 22B includes a negative value (for example, −1 degree). That is, here, 0 degree regarding the inclination angle of the first region 221B of the prism portion 22B includes a minus value in a range caused by processing accuracy (manufacturing error) or the like.

The second region 222B of the prism portion 22B is formed in a shape recessed from the back surface into the base portion 20B. For example, the second region 222B is formed in a triangular shape that is recessed from the back surface into the base 20B in the cross section along the longitudinal direction of the base 20B.

In the prism portion 22B, the ratio R31 of the first region 221B in the length of the base portion 20B in the longitudinal direction is the same as the ratio R11 in the prism portion 22. For example, the length L31 of the first region 221B in the length in the longitudinal direction of the base portion 20B is the length L30 of the entire prism portion 22B in the length in the longitudinal direction of the base portion 20B (hereinafter also referred to as “structural unit length L30”). It is preferable that the ratio R31 to is 60% or more and less than 100%. In the prism portion 22B, the ratio R31 is more preferably 75% or more and less than 100%.

The prism portion 22B is formed so that the structural unit length L30 of the prism portion 22B is 40 μm or more and 500 μm or less. In the prism portion 22B, it is more preferable that the structural unit length L30 of the prism portion 22B is 80 μm or more and 250 μm or less. With the above-described configuration, the optical member 2B has a desired translucency (for example, is transparent) even in the base portion 20B where the prism portion 22B is formed.

Here, the light distribution in the optical member 2B will be described using the light beams IL31 to IL37 shown in FIG. Light rays IL31 to IL37 shown in FIG. 8 virtually indicate the light distribution in the optical member 2B. For example, in the base portion 20B, among the light beams IL31 heading toward the second region 222B, a part of the light beams IL32 is reflected in the direction of the light extraction surface 21B by the second region 222B having a prism function.

Of the light beams IL32 that travel from the base 20B toward the light extraction surface 21B, some of the light beams IL33 are emitted outside the light extraction surface 21B. In addition, among the light beams IL32 that travel from the base portion 20B toward the light extraction surface 21B, some of the light beams IL34 are reflected by the light extraction surface 21B and emitted to the back surface side of the base portion 20B.

In addition, for example, among the light beams IL31 that travel toward the second region 222B in the base portion 20B, some of the light beams IL35 are radiated to the outside from one surface of the second region 222B having a prism function, and are transmitted by the other surface of the second region 222B. It is reflected and emitted to the back side of the base 20B. Further, for example, the light beam IL36 traveling from the inside of the base portion 20B toward the second region 222B passes through the second region 222B and is radiated to the back surface side of the base portion 20B as the light beam IL37. Thus, in the optical member 2B, since it is difficult to suppress the light radiated to the back surface side of the base 20B than the optical member 2 according to the embodiment, the optical member used for the planar illumination device 100 is optical. The member 2 is more preferable than the optical member 2B.

(Modification 4)
In the above-described example, the case where the light emitting surface (light extraction surface) is a flat surface, such as the light extraction surface 21 of the planar lighting device 1, is illustrated. However, the light emission surface (light extraction surface) is not limited to a flat surface. It may be formed in various shapes depending on the purpose. For example, the light guide direction of the light guide plate (optical member) in the surface illumination device, that is, the cross-sectional shape of the light emitting surface (light extraction surface) is not limited to a rectangle, but may be a pyramid shape, an inverted pyramid shape, a barrel shape, or an inverted barrel shape. . This point will be described with reference to FIG. FIG. 9 is a side view showing a planar illumination device according to Modification 4. Specifically, FIG. 9 is a side view showing the optical member 2C in which the cross-sectional shape of the light emitting surface (light extraction surface) is formed in a kamaboko shape. Although FIG. 9 shows an example in which the shape of the front surface is deformed, the deformation may be applied to the back surface, or may be applied to both the front surface and the back surface.

The optical member 2C of the planar illumination device 1C has a base portion 20C that is a transparent body formed in a semi-cylindrical shape whose height increases as the light extraction surface 21C moves toward the central portion in the longitudinal direction. For example, the base portion 20 </ b> C is formed of a light transmissive material like the base portion 20 of the optical member 2. A prism portion 22C is formed on the back surface of the light extraction surface 21C of the optical member 2C. The prism portions 22C are formed side by side in a predetermined direction. For example, the prism portion 22C is formed side by side in the longitudinal direction of the base portion 20C (the left-right direction in FIG. 9). The light source unit 3 is disposed along the side surfaces 23C and 24C of the base 20C of the optical member 2C.

(Modification 5)
Next, the outline of the configuration of the planar illumination device 1D will be described with reference to FIGS. 10 and 11. FIG. 10 is a front view showing a planar lighting device according to Modification 5. FIG. 11 is a side view showing a planar lighting device according to Modification 5.

As shown in FIG. 10, the planar illumination device 1 </ b> D includes an optical member 2 </ b> D and a light source unit 3 </ b> D.

The optical member 2D has a base portion 20D that is a transparent body formed in a flat plate shape. For example, the base portion 20 </ b> D is formed of a light-transmitting material like the base portion 20 of the optical member 2.

Further, as shown in FIG. 11, a prism portion 22D is formed on the back surface of the light extraction surface 21D of the optical member 2D. The prism portions 22D are formed side by side in a predetermined direction. For example, the prism portion 22D is formed side by side in the longitudinal direction of the base portion 20D (the left-right direction in FIG. 11). The prism portion 22D may be formed in the same shape as the prism portion 22, the prism portion 22A, and the prism portion 22B. That is, the prism portion 22D may be formed in any shape as long as a desired light distribution condition is satisfied.

The light source unit 3D includes a holding member 30D, a light source 31D such as an LED, and a light incident element 32D. The light source unit 3D is disposed along the side surfaces 23D and 24D of the base 20D of the optical member 2D. For example, the light source unit 3D is provided as a pair at both ends of the optical member 2D. For example, the pair of holding members 30D holds the optical member 2D from both sides. In FIG. 10, a pair of light sources 3D is provided at both ends of the optical member 2D in the longitudinal direction of the base 20D, and holds the optical member 2D. Each holding member 30D holds the light source 31D and the light incident element 32D. 10 illustrates a state in which the light source 31D and the light incident element 32D are exposed in a front view. However, if the light source 31D and the light incident element 32D are disposed at predetermined positions with respect to the optical member 2D, for example, The cover member 30D may be covered. The optical member 2D may be held by the holding member 30D by covering the vicinity of the side surfaces 23D and 24D with the holding member 30D.

Each light source section 3D is provided with a light source 31D at a position sandwiching the light incident element 32D from the longitudinal direction (vertical direction in FIG. 10) of the light incident element 32D. For example, the two light sources 31D are arranged so that light enters the light incident element 32D from the side end of the light incident element 32D. Note that only one light source 31D may be used, and the light source 31D may be arranged so that light enters the light incident element 32D from one of the side end portions of the light incident element 32D.

For example, the light incident element 32D has a function of converting light emitted from the light source 31D, which is a point light source, into light of a linear light source. For example, the light incident element 32 </ b> D is formed of a light transmissive material like the light incident element 32. The light incident element 32D may be a so-called light bar. The light incident element 32D is provided with one surface intersecting the longitudinal direction facing the optical member 2D. The light incident element 32D is provided with one surface facing the side surfaces 23D and 24D of the base portion 20D. For example, in the light source unit 3D on the left side in FIG. 10, the light incident element 32D is provided along the side surface 23D of the base 20D. Further, in the light source unit 3D on the left side in FIG. 10, the light incident element 32D is provided with one surface facing the side surface 23D of the base 20D. For example, in the light source unit 3D on the right side in FIG. 10, the light incident element 32D is provided along the side surface 24D of the base unit 20D. Further, in the light source unit 3D on the right side in FIG. 10, the light incident element 32D is provided with one surface facing the side surface 24D of the base 20D.

In addition, a mechanism for performing predetermined optical control is provided on a surface 321D (hereinafter also referred to as “reflecting surface 321D”) opposite to the surfaces facing the side surfaces 23D and 24D of the light incident element 32D. For example, the reflecting surface 321D of the light incident element 32D has a function of controlling the light distribution of the light incident from the side end of the light incident element 32D in the direction of the optical member 2D. For example, the reflection surface 321D of the light incident element 32D may include a portion that is roughened to form minute irregularities, has a light scattering function, and a portion that is not roughened. In addition, for example, a prism may be disposed on the reflection surface 321D of the light incident element 32D. The reflection surface 321D of the light incident element 32D may have any configuration as long as light incident from the side end of the light incident element 32D can be distributed in the direction of the optical member 2D.

Further, a predetermined light distribution member may be provided on a surface of the light incident element 32D that faces the side surfaces 23D and 24D of the base 20D, that is, a surface 322D opposite to the reflective surface 321D of the light incident element 32D. For example, a lenticular lens, a diffusing element, a prism, or a TIR-Fresnel lens may be provided as a light distribution member on the surface of the light incident element 32D that faces the side surfaces 23D and 24D of the base 20D. The light incident element 32D may be continuous with the side surfaces 23D and 24D of the base portion 20D. For example, the light incident element 32D may be integrally formed with the base 20D.

Further, the width of the light incident element 32D is preferably equal to or larger than the width of the base portion 20D in the short direction. Thereby, since the planar illumination device 1D is irradiated with the light from the light incident element 32D over the entire lateral direction of the side surfaces 23D and 24D of the optical member 2D, the light extraction surface 21D of the base 20D is more evenly distributed. Can emit light.

(Modification 6)
Next, the outline of the configuration of the planar illumination device 1E will be described with reference to FIG. FIG. 12 is a front view showing a main part of a planar lighting device according to Modification 6. The planar illumination device 1E is different from the planar illumination device 1D in that the number of light incident elements 32E and 33E corresponding to the light sources 311E and 312E is used. Since the other points are the same as those of the planar illumination device 1D in the modified example 5, “** D” in the description of the planar illumination device 1D is replaced with “** E”. For example, a plurality of light incident elements 32E may be stacked, or may be formed in a wedge shape and the light source 31E may be arranged on one side.

As shown in FIG. 12, the planar illumination device 1E includes an optical member 2E and a light source unit 3E.

The optical member 2E has a base portion 20E that is a transparent body formed in a flat plate shape. For example, the base portion 20 </ b> E is formed of a light transmissive material like the base portion 20 of the optical member 2. Further, a prism portion (not shown) is formed on the back surface of the light extraction surface 21E of the optical member 2E. The prism portion may be formed in the same shape as the prism portion 22, the prism portion 22A, and the prism portion 22B. In other words, the prism portion may be formed in any shape as long as a desired light distribution condition is satisfied.

The light source unit 3E includes a holding member 30E, two light sources 311E and 312E, and two light incident elements 32E and 33E corresponding to the light sources 311E and 312E, respectively. For example, the light source unit 3E is provided as a pair at both ends of the optical member 2E. In FIG. 12, the light source part 3E shows the case where it arrange | positions along the side surface 23E of the base 20E of the optical member 2E.

The light incident element 32E is provided along the short side direction of the base portion 20E with the one surface facing the side surface 23E of the base portion 20E. For example, the light incident element 32E is arranged so that the thickness decreases as it goes in one direction along the short direction of the base 20E. In FIG. 12, the light incident element 32E is arranged so that the thickness decreases as it goes from top to bottom along the short direction of the base 20E.

Further, the light incident element 33E is disposed between the light incident element 32E and the base portion 20E, and is provided so as to face one side of the side surface 23E of the base portion 20E along the short direction of the base portion 20E. For example, the light incident element 33E is arranged so that the thickness decreases as it goes in one direction along the short direction of the base 20E. In FIG. 12, the light incident element 33 </ b> E is arranged so that the thickness decreases as it goes from the bottom to the top along the short direction of the base portion 20 </ b> E.

Further, a mechanism for performing predetermined optical control is provided on a surface 321E opposite to the surface facing the side surface 23E of the light incident element 32E (hereinafter also referred to as “reflecting surface 321E”). For example, the reflecting surface 321E of the light incident element 32E has a function of controlling the light distribution from the side end of the light incident element 32E in the direction of the optical member 2E. For example, the reflection surface 321E of the light incident element 32E is formed in the same manner as the reflection surface 321D of the light incident element 32D. The reflection surface 321E of the light incident element 32E may have any configuration as long as light incident from the side end of the light incident element 32E can be distributed in the direction of the optical member 2E.

Also, on the surface 331E opposite to the surface facing the side surface 23E of the light incident element 33E (hereinafter, also referred to as “reflection surface 331E”), a mechanism for performing predetermined optical control is provided in the same manner as the reflection surface 321E. For example, the reflection surface 331E of the light incident element 33E has a function of controlling light distribution from the side end of the light incident element 33E in the direction of the optical member 2E.

Note that the above-described planar illumination device 1 may be used for a high-mount light of an automobile. For example, the planar lighting device 1 may be attached to the rear window of an automobile. Moreover, the optical member 2 is not limited to the object for automobiles, and may be used for a planar lighting device that needs to suppress light emission from the back surface.

Further, the present invention is not limited by the above embodiment. What was comprised combining each component mentioned above suitably is also contained in this invention. Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above-described embodiment, and various modifications can be made.

DESCRIPTION OF SYMBOLS 1 Planar illuminating device 2 Optical member 20 Base 21 Light extraction surface 22 Prism part 221 1st area | region 222 2nd area | region 23 Side surface 24 Side surface 3 Light source part 30 Holding member 31 Light source 32 Light incident element 321 Light incident surface

Claims (20)

1. A base which is a transparent body formed in a flat plate shape;
   A prism portion formed on one side in the thickness direction of the base portion and arranged in a predetermined direction, wherein an inclination angle with respect to a plane perpendicular to the thickness direction of the base portion in a cross section along the predetermined direction is 0 degree or more and 8 degrees or less A prism portion in which a second region having a prism shape is continuous with a certain first region, and a ratio of the first region in a length in the predetermined direction is 60% or more and less than 100%;
   An optical member comprising:
2. The optical member according to claim 1, wherein an inclination angle of the first region of the prism portion is 0 degree or more and 4 degrees or less.
3. The optical member according to claim 1 or 2, wherein a ratio of the first region of the prism portion in the length in the predetermined direction is 75% or more and less than 100%.
4. 4. The optical member according to claim 1, wherein a length of the prism portion in the predetermined direction is not less than 40 μm and not more than 500 μm.
5. The optical member according to claim 4, wherein a length of the prism portion in the predetermined direction is not less than 80 μm and not more than 250 μm.
6. In the cross section along the predetermined direction, the first region of one prism portion has a shape extending from a first height in the thickness direction of the base portion to a second height higher than the first height, The second region of one prism portion has a shape in which one end portion is continuous with the first region at the second height and extends to the first height, and the other end portion at the first height. 6. The optical member according to claim 1, wherein is continuous with the first region of the other prism portion.
7. The optical member according to any one of claims 1 to 6,
   A light source portion disposed along one side surface of the base portion of the optical member;
   A planar lighting device.
8. The planar illumination device according to claim 7, wherein a width of a region where the luminance is uniform in the light source unit is equal to or greater than a width of the one side surface of the base portion.
9. The optical member has the prism portion formed on the back surface of the light extraction surface of the base,
   The planar illumination device according to claim 7 or 8, wherein a luminance ratio, which is a ratio of the luminance of the light extraction surface to the luminance of the back surface, is 20 or more.
10. The planar illumination device according to claim 9, wherein the regular reflectance of the light extraction surface of the base is 1.6% or less.
11. The planar illumination device according to claim 10, wherein a low reflection portion that suppresses reflection into the base portion is provided on the light extraction surface side of the base portion.
12. The planar illumination device according to claim 10 or 11, wherein the regular reflectance of the light extraction surface of the base is 0.8% or less.
13. The planar illumination device according to claim 12, wherein the regular reflectance of the light extraction surface of the base is 0.4% or less.
14. The planar illumination device according to any one of claims 9 to 13, wherein the luminance ratio of the luminance of the light extraction surface to the luminance of the back surface is 40 or more.
15. The planar illumination device according to claim 14, wherein a luminance suppression unit that suppresses light emission to the back side is provided on the back side of the base.
16. The planar illumination device according to claim 14 or 15, wherein the luminance ratio of the luminance of the light extraction surface to the luminance of the back surface is 100 or more.
17. The planar illumination device according to any one of claims 9 to 16, wherein the luminance ratio is a ratio of a front luminance on the light extraction surface side to a front luminance on the back surface side.
18. A method of processing an optical member including a prism region where prism processing is performed on one surface of a base portion which is a flat plate-shaped transparent body and a non-prism region where prism processing is not performed,
    A processing method of performing prism processing on the prism region of the optical member by forming the prism region by post-processing on an optical member that is not subjected to prism processing on the one surface.
19. A method of processing an optical member including a prism region where prism processing is performed on one surface of a base portion which is a flat plate-shaped transparent body and a non-prism region where prism processing is not performed,
    By forming the non-prism region by removing the prism processing by post-processing on the optical member on which the one surface is subjected to prism processing,
    A processing method for performing prism processing on the prism region of the optical member.
20. A method of processing an optical member including a prism region where prism processing is performed on one surface of a base portion which is a flat plate-shaped transparent body and a non-prism region where prism processing is not performed,
    By forming the non-prism area on the one surface by forming the prism area by post-processing on an optical member generated lower than the height of the area where the prism processing is performed,
    A processing method for performing prism processing on the prism region of the optical member.

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