Lighting devices and display devices

Abstract

To improve the uniformity of brightness. [Solution] The lighting device 12 comprises a light source 40 having a light-emitting surface 40A that emits light for irradiating the main surface 11A of the object to be irradiated 11, and a concave mirror 43 positioned laterally to the object to be irradiated 11 and facing the light-emitting surface 40A of the light source 40, wherein the concave mirror 43 has a reflective surface 43A configured to cause reflected light to travel along the main surface 11A of the object to be irradiated.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a lighting device and a display device with improved luminance uniformity.

Background Art

[0002] Conventionally, as an example of a lighting device, the one described in Patent Document 1 below is known. The lighting device described in Patent Document 1 is for illuminating an artwork, and includes a frame used for holding the artwork, a light source and a collimating lens inside the frame. The frame is composed of four members, and two thin openings are formed along the front surface of each member. The light source and the collimating lens are arranged in the thin openings of two opposing members.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the lighting device described in Patent Document 1 above, a Fresnel lens is used as the collimating lens. However, the light emitted from the exit surface of the Fresnel lens tends to have a deteriorated parallelism as it moves away from the optical axis of the light source. For this reason, much of the light that does not exit parallel from the exit surface of the Fresnel lens is directly emitted from the glass plate without irradiating the artwork. Therefore, there was a risk that the luminance uniformity within the main surface of the artwork would deteriorate.

[0005] The technology described in this specification has been completed based on the above circumstances, and aims to improve the luminance uniformity.

Means for Solving the Problems

[0006] (1) An illumination device relating to the technology described herein comprises a light source having a light-emitting surface that emits light for illuminating the main surface of an object to be illuminated, and a concave mirror positioned laterally to the object to be illuminated and facing the light-emitting surface of the light source, wherein the concave mirror has a reflective surface configured to cause reflected light to propagate along the main surface of the object to be illuminated.

[0007] (2) In addition to (1) above, the lighting device may also include a reflective material that extends from the light source to the concave mirror and reflects light.

[0008] (3) In addition to (1) or (2) above, the lighting device may also include a louver positioned laterally to the object to be illuminated and facing the reflective surface, wherein the louver has two light-shielding portions spaced apart in the direction normal to the main surface to be illuminated, and a light-transmitting portion positioned between the two light-shielding portions.

[0009] (4) A display device relating to the technology described herein comprises an illumination device as described in any of (1) to (3) above, and a display panel that displays using light from the light source, wherein the display panel is the illuminated object and has a display surface on which an image is displayed as the main surface to be illuminated.

[0010] (5) In addition to (4) above, the display device is configured such that the light source and the concave mirror are positioned laterally to the first end which is included in the outer peripheral end of the display panel, and the light source may be positioned closer to the first end than the concave mirror.

[0011] (6) In addition to (5) above, the display device may also include a specular reflecting material that specularly reflects light, which is positioned laterally to the second end of the outer peripheral edge of the display panel where the light source and the concave mirror are not located.

[0012] (7) In addition to (6) above, the display device may have a rectangular display panel with one first end and three second ends at its outer peripheral edge, and the specular reflector may be positioned laterally to each of the three second ends.

[0013] (8) In addition to (6) above, the display device has a rectangular display panel and includes a third end, one first end, and two second ends at its outer peripheral edge, where the light source, the concave mirror, and the specular reflector are not provided; the display panel includes a first display panel and a second display panel, the first display panel and the second display panel are arranged so that their respective third ends are aligned; and the specular reflector may be arranged laterally to each of the two second ends provided on the first display panel and the second display panel.

[0014] (9) In addition to (6) above, the display device has a rectangular display panel and includes two third ends on its outer periphery where the light source, the concave mirror, and the specular reflector are not provided, one first end, and one second end, and the display panel includes a first display panel, a second display panel, a third display panel, and a fourth display panel, and the first and second display panels are arranged so that one of their third ends is adjacent to the other, the third and fourth display panels are arranged so that one of their third ends is adjacent to the other, the first and third display panels are arranged so that the other of their third ends is adjacent to the other, and the specular reflector may be positioned laterally to each of the second ends provided on the first, second, third, and fourth display panels.

[0015] (10) In addition to (6) above, the display device includes a first display panel, a second display panel, a third display panel, a fourth display panel, a fifth display panel, and a sixth display panel, wherein the first display panel, the second display panel, the third display panel, and the fourth display panel are rectangular and have two third ends, one first end, and one second end at their outer periphery, where the light source, the concave mirror, and the specular reflector are not provided, and the fifth display panel and the sixth display panel are rectangular and have an outer periphery The peripheral edge includes three third ends where the light source, the concave mirror, and the specular reflector are not positioned, and one first end, and the first and second display panels are arranged so that one of each of their third ends is aligned, the third and fourth display panels are arranged so that one of each of their third ends is aligned, and the fifth and sixth display panels are arranged so that their first of their third ends is aligned, forming a pair, and there are n such pairs (n: a natural number), and the n pairs of the fifth and sixth display panels are , sandwiched between the first display panel and the third display panel, and sandwiched between the second display panel and the fourth display panel, wherein the other third end of the first display panel is arranged to align with the second third end of the fifth display panel included in the n sets of the fifth and sixth display panels, wherein the other third end of the third display panel is arranged to align with the third third end of the fifth display panel included in the n sets of the fifth and sixth display panels, and the second display panel is, The other third end of the fourth display panel is arranged to align with the second third end of the sixth display panel included in the n sets of fifth and sixth display panels, and the other third end of the fourth display panel is arranged to align with the third third end of the sixth display panel included in the n sets of fifth and sixth display panels, and the specular reflector may be arranged laterally to each of the second ends provided on the first, second, third, and fourth display panels.

[0016] (11) Further, in addition to any one of (4) to (10) above, the display device has a facing surface facing the display surface, and includes a transmissive panel disposed with a gap between the display surface and the facing surface, and the concave mirror may be disposed such that the reflective surface faces the gap.

[0017] (12) Further, in addition to any one of (4) to (11) above, the display panel may be an electronic paper display. [Effect of the Invention]

[0018] According to the technology described in this specification, the uniformity of luminance can be improved. [Brief Description of the Drawings]

[0019] [Figure 1] Plan view of the display device according to Embodiment 1 [Figure 2] Cross-sectional view taken along line ii-ii of FIG. 1 in the display device according to Embodiment 1 [Figure 3] Plan view of the backplane of the electronic paper display included in the display device according to Embodiment 1 [Figure 4] Cross-sectional view showing the cross-sectional configuration of the display area in the electronic paper display according to Embodiment 1 [Figure 5] Enlarged cross-sectional view of the main part of FIG. 2 in the display device according to Embodiment 1 [Figure 6] Cross-sectional view showing the configuration of Comparative Example 1 of Comparative Experiment 1 according to Embodiment 1 [Figure 7] Table including a graph showing the angular characteristics of the illumination light of the front light device according to Example 1 of Comparative Experiment 1 according to Embodiment 1 [[ID=三十九]] [Figure 8] Table including a graph showing the angular characteristics of the illumination light of the front light device according to Comparative Example 1 of Comparative Experiment 1 according to Embodiment 1 "" [Figure 9] View showing the illuminance distribution of the illumination light of the front light device according to Comparative Example 1 of Comparative Experiment 1 according to Embodiment 1 [Figure 10]Figure showing the illuminance distribution of the illumination light of the front light device according to Example 1 of Comparative Experiment 1 according to Embodiment 1 [Figure 11] Plan view of the display device according to Embodiment 2 [Figure 12] Cross-sectional view taken along line xii-xii of FIG. 11 in the display device according to Embodiment 2 [Figure 13] Cross-sectional view taken along line xiii-xiii of FIG. 11 in the display device according to Embodiment 2 [Figure 14] Figure showing the illuminance distribution of the illumination light of the front light device according to Comparative Example ② of Comparative Experiment 2 according to Embodiment 2 [Figure 15] Figure showing the illuminance distribution of the illumination light of the front light device according to Comparative Example ③ of Comparative Experiment 2 according to Embodiment 2 [Figure 16] Figure showing the illuminance distribution of the illumination light of the front light device according to Example ② of Comparative Experiment 2 according to Embodiment 2 [Figure 17] Plan view of the display device according to Embodiment 3 [Figure 18] Cross-sectional view taken along line xviii-xviii of FIG. 17 in the display device according to Embodiment 3 [Figure 19] Cross-sectional view taken along line xix-xix of FIG. 17 in the display device according to Embodiment ③ [Figure 20] Enlarged cross-sectional view of the main part of FIG. XVIII in the display device according to Embodiment 3 [Figure 21] Figure showing the luminance distribution of the illumination light of the front light device according to Example ③ of Demonstration Experiment 1 according to Embodiment 3 [Figure 22] Graph showing the luminance distribution in the X-axis direction in the first electronic paper display according to Example ③ of Demonstration Experiment 1 according to Embodiment 3 [Figure 23] Graph showing the luminance distribution in the X-axis direction in the second electronic paper display according to Example ③ of Demonstration Experiment 1 according to Embodiment 3 [Figure 24] Plan view of the display device according to Embodiment 4 [Figure 25] Cross-sectional view taken along line xxv-xxv of FIG. 24 in the display device according to Embodiment 4 [Figure 26]Cross-sectional view of the display device according to Embodiment 4, shown along the line xxvi-xxvi in ​​Figure 24. [Figure 27] Plan view of the display device according to Embodiment 5 [Figure 28] Cross-sectional view of the display device according to Embodiment 5, shown along line xxviii-xxviii in Figure 27. [Modes for carrying out the invention]

[0020] <Embodiment 1> Embodiment 1 will be described with reference to Figures 1 to 10. In this embodiment, a display device 10 equipped with an electronic paper display 11 (EPD: illuminated object) as a display panel is provided as an example. Note that parts of each drawing show the X, Y, and Z axes, and each axis is drawn so that it corresponds to the direction shown in each drawing. Also, the upper side of Figures 2, 4, and 5 is considered the front side, and the lower side of the same figure is considered the back side.

[0021] As shown in Figures 1 and 2, the display device 10 according to this embodiment comprises an electronic paper display (display panel) 11, a front light device (illumination device) 12 that irradiates light onto the electronic paper display 11 from the front side, and a light-transmitting panel 13 that faces the electronic paper display 11 with a gap in front of it.

[0022] As shown in Figures 1 and 2, the electronic paper display 11 and the light-transmitting panel 13 are arranged so as to overlap each other when viewed in a plane, and both have a horizontally elongated rectangular shape in their planar form. In this embodiment, both the electronic paper display 11 and the light-transmitting panel 13 are approximately A2 size. The main front surface of the electronic paper display 11 is the display surface (illuminated main surface) 11A on which images can be displayed. The display surface 11A has a display area AA on the central side where the image is displayed, and a frame-like portion surrounding the display area AA is a non-display area NAA where the image is not displayed (see Figure 3). The display area AA has a long side dimension of approximately 592 mm and a short side dimension of approximately 418 mm. The display surface 11A is a plane that is substantially parallel to the X-axis and Y-axis directions of each drawing, and its normal direction coincides with the Z-axis direction of each drawing.

[0023] The electronic paper display 11 operates using, for example, a microcapsule electrophoresis method, and the image displayed on the display surface 11A can be electrically rewritten, and the display state of the image can be maintained even when there is no power supply. The electronic paper display 11 has a backplane 20 for rewriting the image, etc. The backplane 20 has a configuration that is generally similar to that of an active matrix substrate used in liquid crystal display devices, etc.

[0024] The electrical configuration of the backplane 20 will be explained using Figure 3. As shown in Figure 3, the display area AA of the backplane 20 is provided with TFTs (transistors, switching elements) 21 and pixel electrodes 22. Multiple TFTs 21 and pixel electrodes 22 are arranged in a matrix (arrangement) with spacing along the X-axis and Y-axis directions. Around these TFTs 21 and pixel electrodes 22, gate wiring (scanning wiring) 23 and source wiring (image wiring, signal wiring) 24 are arranged orthogonally (intersecting) with each other. Multiple gate wirings 23 extend along the X-axis direction and are arranged with spacing along the Y-axis direction. Multiple source wirings 24 extend along the Y-axis direction and are arranged with spacing along the X-axis direction.

[0025] As shown in Figure 3, the TFT 21 includes a gate electrode 21A connected to the gate wiring 23, a source electrode 21B connected to the source wiring 24, a drain electrode 21C connected to the pixel electrode 22, and a semiconductor portion 21D made of a semiconductor material connected to the source electrode 21B and the drain electrode 21C. The semiconductor material of the semiconductor portion 21D is, for example, an oxide semiconductor material. The TFT 21 is driven based on a scanning signal supplied to the gate electrode 21A by the gate wiring 23. This scanning signal contains a potential higher than the threshold voltage of the TFT 21. As a result, a channel region is created in the semiconductor portion 21D, making it possible for charge to move between the source electrode 21B and the drain electrode 21C through the channel region. Therefore, the potential related to the image signal (data signal) supplied to the source electrode 21B by the source wiring 24 is supplied to the drain electrode 21C via the semiconductor portion 21D. As a result, the pixel electrode 22 is charged to the potential related to the image signal.

[0026] As shown in Figure 3, the non-display area NAA of the backplane 20 is provided with a gate circuit section 25 and a source driver 26. The gate circuit section 25 is positioned adjacent to the display area AA on one side in the X-axis direction (the left side in Figure 3). The gate circuit section 25 is provided in a strip-shaped area extending along the Y-axis direction. Multiple gate wires 23 each have portions that are drawn out into the non-display area NAA, and these drawn-out portions are connected to the gate circuit section 25. The gate circuit section 25 can supply scanning signals to the multiple gate wires 23. The gate circuit section 25 is monolithically provided on the backplane 20. The gate circuit section 25 is a GDM (Gate Driver Monolithic) circuit. Various signals transmitted by a flexible substrate (not shown) connected to the backplane 20 are supplied to the gate circuit section 25.

[0027] As shown in Figure 3, the source driver 26 is positioned adjacent to one side (the lower side in Figure 3) of the display area AA in the Y-axis direction. The source driver 26 has a horizontally elongated rectangular shape in its planar configuration. Each of the multiple source wires 24 has a portion that extends into the non-display area NAA, and these extended portions are connected to the source driver 26. The source driver 26 can supply image signals to the multiple source wires 24. The source driver 26 consists of an LSI chip with an internal drive circuit. The source driver 26 is mounted on the backplane 20. The source driver 26 processes various signals transmitted by a flexible substrate (not shown) connected to the backplane 20.

[0028] The schematic cross-sectional configuration of the display area AA in the electronic paper display 11 will be explained using Figure 4. As shown in Figure 4, the electronic paper display 11 has the backplane 20 described above and an electronic paper layer (display layer) 27 arranged to overlap the backplane 20 on the front side. The backplane 20 and the electronic paper layer 27 are bonded together by an adhesive layer (not shown). The electronic paper layer 27 is also called a front panel laminate (FPL). The electronic paper layer 27 has a pair of films 28, 29, a microcapsule 30 sandwiched between the two films 28, 29, a transparent electrode (counter electrode) 31 laminated on the front side of the front side (upper side in Figure 4) film 28 of the pair of films 28, 29, and a color filter 32 laminated on the front side of the transparent electrode 31.

[0029] The detailed configuration of the electronic paper layer 27 will now be described. The pair of films 28 and 29 constituting the electronic paper layer 27 are both made of a transparent synthetic resin material or the like, and as shown in Figure 4, they are arranged facing each other with a predetermined distance between them in the Z-axis direction. Multiple microcapsules 30 are arranged in a single layer between the two films 28 and 29. Multiple microcapsules 30 are superimposed on one pixel electrode 22 provided on the backplane 20. The microcapsules 30 contain at least black particles 33 that exhibit a black color and white particles 34 that exhibit a white color as charged particles. The black particles 33 are made of, for example, negatively charged carbon black particles. The white particles 34 are made of, for example, positively charged titanium oxide particles. The microcapsules 30 contain an insulating fluid 35 in which the black particles 33 and white particles 34 are dispersed. The insulating fluid 35 is made of, for example, silicone oil.

[0030] The transparent electrode 31 is made of a transparent electrode material such as ITO (Indium Tin Oxide). As shown in Figure 4, the transparent electrode 31 is formed in a solid shape so as to extend over at least the entire display area AA, and is superimposed on all the pixel electrodes 22 on the backplane 20. The films 28, 29 and the transparent electrode 31 can transmit ambient light incident on the electron paper layer 27 from the front side. The color filter 32 includes, for example, three colors: red, green, and blue. Each color filter 32 is superimposed on a specific pixel electrode 22 on the backplane 20 and, together with the pixel electrode 22, constitutes a pixel, which is a display unit. The color filter 32 that emits red constitutes a red pixel (R) together with the superimposed pixel electrode 22. The color filter 32 that emits green constitutes a green pixel (G) together with the superimposed pixel electrode 22. The color filter 32 that emits blue constitutes a blue pixel (B) together with the superimposed pixel electrode 22. Of the multiple pixel electrodes 22, those that do not overlap with the color filter 32 constitute white pixels (W) that exhibit a white color.

[0031] As shown in Figure 4, each of the multiple pixel electrodes 22 is either charged to a predetermined potential or not. This creates a potential difference between each pixel electrode 22 and the transparent electrode 31, corresponding to the potential of each pixel electrode 22. At this time, for example, if an electric field that is negative relative to the transparent electrode 31 is applied to a certain pixel electrode 22 (the leftmost pixel electrode 22 in Figure 4), the negatively charged black particles 33 are repelled by the negative electric field and move to the front side of the microcapsule 30. Also, the positively charged white particles 34 are attracted to the negative electric field and move to the back side of the microcapsule 30. As a result, light incident on the electronic paper layer 27 from the front side is absorbed by the black particles 33 arranged on the front side of the microcapsule 30. Therefore, even if a color filter 32 is present, the portion of the display surface 11A that overlaps with the microcapsule 30 does not display the color corresponding to the color filter 32, and appears black.

[0032] On the other hand, for example, when an electric field that is positive relative to the transparent electrode 31 is applied to a certain pixel electrode 22 (the second pixel electrode 22 from the left in Figure 4 and the pixel electrode 22 at the right end of Figure 4), the positively charged white particles 34 are repelled by the positive electric field and move to the front side of the microcapsule 30. Also, the negatively charged black particles 33 are attracted to the positive electric field and move to the back side of the microcapsule 30. As a result, light incident on the electronic paper layer 27 from the front side is reflected by the white particles 34 arranged on the front side of the microcapsule 30, so that the portion of the display surface 11A that overlaps with the microcapsule 30 appears white in, for example, the white pixels (W) where the color filter 32 is not placed, and the pixels (R), (G), (B) of each color where the color filter 32 is placed appear in the color corresponding to the color filter 32.

[0033] For example, if a certain pixel electrode 22 (the second pixel electrode 22 from the right in Figure 4) is not charged and is in an electric field-free state, then black particles 33 and white particles 34 will be mixed on the front and back sides of the microcapsule 30, respectively. In this case, light incident on the electronic paper layer 27 from the front side will be absorbed by the black particles 33 arranged on the front side of the microcapsule 30 or reflected by the white particles 34, causing the microcapsule 30 to appear gray. In this way, it is possible to display a color image on the display surface 11A.

[0034] As shown in Figures 1 and 2, the translucent panel 13 is approximately the same size as the electronic paper display 11. The translucent panel 13 is made of glass or synthetic resin material (e.g., acrylic material), is almost transparent, and has excellent light transmission properties. The translucent panel 13 is held by a holding means (not shown) at a predetermined distance from the front side of the electronic paper display 11. The translucent panel 13 has a facing surface 13A that faces the display surface 11A of the electronic paper display 11. The translucent panel 13 has a thickness of, for example, about 3 mm. A gap S is interposed between the facing surface 13A of the translucent panel 13 and the display surface 11A of the electronic paper display 11. The gap S has a thickness of, for example, about 10 mm. Air is present in the gap S.

[0035] As shown in Figures 1 and 2, the front light device 12 includes an LED (light source) 40 having a light-emitting surface 40A, an LED substrate (light source substrate) 41 on which the LED 40 is mounted, a reflective sheet (reflective material) 42 that reflects light from the LED 40, a concave mirror 43 that reflects light from the LED 40, and a housing 44 that houses the LED 40, LED substrate 41, reflective sheet 42, and concave mirror 43. The LED 40, LED substrate 41, reflective sheet 42, concave mirror 43, and housing 4 that constitute the front light device 12 are arranged adjacent to the side of the first end (the left short end in Figures 1 and 2) 11E1 included in the outer peripheral edge of the electronic paper display 11.

[0036] The housing 44 is made of, for example, a synthetic resin material, extends along the Y-axis direction as shown in Figure 1, and has a vertically elongated rectangular shape when viewed in plan. As shown in Figure 2, the housing 44 as a whole has a "U" shape in cross-section and has a first housing component 44A, a second housing component 44B that is spaced apart from and opposite to the first housing component 44A, and a third housing component 44C that is connected to the first housing component 44A and the second housing component 44B. As shown in Figure 5, the first housing component 44A and the second housing component 44B have a plate-like main surface that is generally parallel to the display surface 11A. The first housing component 44A is located on the back side of the second housing component 44B, spaced apart from it. The third housing component 44C has a plate-like main surface that is generally parallel to the Y-axis direction and the Z-axis direction and is generally perpendicular to the display surface 11A. The third housing component 44C has its rear end in the Z-axis direction connected to the end of the first housing component 44A opposite to the electronic paper display 11 (left side in Figure 2), and its front end in the Z-axis direction connected to the end of the second housing component 44B opposite to the electronic paper display 11. The housing 44 has openings 44D at the electronic paper display 11 side (right side in Figure 2) of both the first housing component 44A and the second housing component 44B, which open toward the gap S between the electronic paper display 11 and the light-transmitting panel 13. The internal space of the housing 44 (the space enclosed by the first housing component 44A, the second housing component 44B, and the third housing component 44C) is in communication with the gap S between the electronic paper display 11 and the light-transmitting panel 13 through the openings 44D.

[0037] As shown in Figure 2, LED 40 is a so-called side-emitting type, where the side adjacent to the bottom surface in contact with the mounted LED substrate 41 is the light-emitting surface 40A. The light-emitting surface 40A of LED 40 is a surface parallel to the Y-axis and Z-axis directions, and its normal direction coincides with the X-axis direction. The optical axis AX of LED 40 coincides with the X-axis direction. Here, "optical axis" refers to the axis that coincides with the direction of propagation of the light with the highest light intensity (peak) among the light emitted by LED 40. LED 40 has a light distribution that spreads out in a roughly fan shape in the Y-axis direction (horizontal direction) and Z-axis direction (vertical direction) with respect to the optical axis AX. As shown in Figure 5, LED 40 is positioned so that the light-emitting surface 40A faces away from the electronic paper display 11 in the X-axis direction (left side in Figure 5, towards the third housing component 44C and the concave mirror 43). LED 40 is positioned closer to the first end 11E1 of the electronic paper display 11 than the concave mirror 43, which will be described later. LED 40 is configured in which an LED chip is sealed with a sealing material on a substrate portion fixed to an LED substrate 41. The LED chip in LED 40 emits monochromatic light, for example, blue light. The sealing material in LED 40 contains dispersed phosphors. The phosphors contained in the sealing material include yellow phosphors, green phosphors, red phosphors, etc. LED 40, which has such an LED chip and sealing material, emits white light as a whole.

[0038] The LED substrate 41 is constructed by laminating metal foil, such as copper, on a flexible film-like substrate (FPC) made of insulating material, onto which numerous wiring patterns are formed. As shown in Figures 1 and 2, the LED substrate 41 is an elongated strip extending along the Y-axis. Multiple LEDs 40 are mounted on the LED substrate 41 in a linear arrangement along its own extension direction (Y-axis direction) to form a single row. The multiple LEDs 40 may be arranged, for example, at equal intervals. As shown in Figure 5, the LED substrate 41 is mounted on the inner surface (facing the second housing component 44B) of the first housing component 44A of the housing 44, with its main surface positioned parallel to the display surface 11A. As shown in Figure 1, two LED substrates 41 are arranged side by side along the Y-axis on the inner surface of the first housing component 44A. Multiple LEDs 40 provided on each of the two LED substrates 41 are arranged in a linear arrangement to form a single row. Furthermore, a portion of the LED board 41 is extended outside the housing 44 and connected to a power supply unit (not shown), thereby enabling power supply to the LED 40.

[0039] The reflective sheet 42 is in the form of a film and is designed to specularly reflect light through its surface. As shown in Figures 1 and 2, the reflective sheet 42 is in the form of an elongated strip extending along the Y-axis direction, similar to the LED substrate 41, and its length (in the Y-axis direction) is the same as that of the LED substrate 41. As shown in Figure 5, the reflective sheet 42 is mounted on the inner surface (the surface facing the second housing component 44B) of the first housing component 44A of the housing 44, similar to the LED substrate 41, with its main surface positioned parallel to the display surface 11A. The reflective sheet 42 extends along the X-axis direction from the LED 40 to the concave mirror 43, with a portion of it overlapping the LED substrate 41. The reflective sheet 42 can specularly reflect light emitted diagonally downward from the light-emitting surface 40A of the LED 40 and direct it towards the concave mirror 43. This improves the efficiency of light utilization. The reflective sheet 42 is positioned to cross all the LEDs 40 mounted on the LED substrate 41. In other words, the reflective sheet 42 is also present between two adjacent LEDs 40 in the Y-axis direction, so it can specularly reflect light traveling diagonally in the Y-axis direction from the light-emitting surface 40A of the LEDs 40. Similar to the LED substrate 41, two reflective sheets 42 are positioned side by side in the Y-axis direction on the inner surface of the first housing component 44A.

[0040] The concave mirror 43 is provided with a reflective surface 43A that reflects light by forming a concave portion on a substrate made of glass or synthetic resin material and depositing a metal film (e.g., an aluminum film) onto the concave portion. As shown in Figure 2, the concave mirror 43 is positioned laterally to the electronic paper display 11 and is arranged to face the light-emitting surface 40A of the LED 40. Specifically, the concave mirror 43 is mounted on the inner surface (the surface facing the opening 44D) of the third housing component 44C of the housing 44, and the reflective surface 43A faces the light-emitting surface 40A of the LED 40 and is exposed to the gap S between the electronic paper display 11 and the light-transmitting panel 13 through the opening 44D. As a result, the light emitted from the light-emitting surface 40A of the LED 40 is either directly reflected by the reflective surface 43A or specularly reflected by the reflective sheet 42 and then indirectly reflected by the reflective surface 43A, so that it travels through the opening 44D into the gap S between the electronic paper display 11 and the light-transmitting panel 13. The concave mirror 43 is positioned further away from the first end 11E1 of the electronic paper display 11 than the LED 40. Therefore, the concave mirror 43 is designed to reflect the light emitted from the light-emitting surface 40A of the LED 40, which is positioned relatively close to the first end 11E1, and illuminate the display surface 11A. The width dimension (dimension in the Z-axis direction) of the concave mirror 43 is equal to the width dimension of the third housing component 44C. As shown in Figure 1, the concave mirror 43 extends along the Y-axis direction, and its length dimension (dimension in the Y-axis direction) is equal to the length dimension of the LED substrate 41. The concave mirror 43 is positioned so that its reflective surface 43A crosses all the LEDs 40 mounted on the LED substrate 41. In other words, the concave mirror 43 is also present between two adjacent LEDs 40 in the Y-axis direction, so that light traveling diagonally in the Y-axis direction from the light-emitting surface 40A of the LED 40 can also be reflected by the reflective surface 43A. Similar to the LED substrate 41, two concave mirrors 43 are arranged side by side in the Y-axis direction on the inner surface of the third housing component 44C.

[0041] As shown in Figure 5, the concave mirror 43 is positioned such that the focal point of the reflective surface 43A is located on the light-emitting surface 40A of the LED 40. Furthermore, the reflective surface 43A of the concave mirror 43 is aspherical to eliminate spherical aberration, and is, for example, a parabolic surface. More specifically, the concave mirror 43 is configured such that the reflective surface 43A protrudes towards the LED 40 (right side of Figure 5) as it moves away from the LED 40 in the Z-axis direction (upper end of Figure 5), and retracts towards the third housing component 44C (left side of Figure 5) as it moves closer to the LED 40 in the Z-axis direction (lower end of Figure 5), resulting in an overall concave shape. This allows the reflective surface 43A to efficiently generate parallel rays by reflecting light emitted from the light-emitting surface 40A where the focal point is located. The parallel rays contained in the light reflected by the reflective surface 43A are assumed to travel along the X-axis direction of each drawing, that is, along the display surface 11A.

[0042] With this configuration, the light emitted from the light-emitting surface 40A of the LED 40 is reflected by the reflective surface 43A of the concave mirror 43, which is facing the light-emitting surface 40A and positioned laterally to the electronic paper display 11, and then irradiated onto the display surface 11A of the electronic paper display 11. The concave mirror 43 is configured so that the light reflected by the reflective surface 43A travels along the display surface 11A of the electronic paper display 11, thus mitigating any difference in the amount of irradiated light between the part of the display surface 11A close to the concave mirror 43 and the part far from the concave mirror 43. In particular, compared to the conventional case using a Fresnel lens, the reflected light from the reflective surface 43A of the concave mirror 43 maintains its parallelism more easily even when it is far from the optical axis AX of the LED 40, so that more light can be irradiated onto the part of the display surface 11A far from the concave mirror 43, and light that is not irradiated onto the display surface 11A and is emitted to the outside near the concave mirror 43 can be suppressed. This improves the uniformity of brightness (illuminance) within the display surface 11A of the electronic paper display 11, thereby improving the display quality of the image displayed on the display surface 11A.

[0043] Furthermore, in this embodiment, as shown in Figure 5, a reflective sheet 42 is provided that extends from the LED 40 to the concave mirror 43. Therefore, light emitted from the light-emitting surface 40A of the LED 40 that does not directly go to the reflective surface 43A of the concave mirror 43 can be reflected by the reflective sheet 42 before reaching the reflective surface 43A of the concave mirror 43. This improves the efficiency of light utilization.

[0044] Furthermore, in this embodiment, as shown in Figure 5, the concave mirror 43 is positioned so that its reflective surface 43A faces the gap S created between the display surface 11A of the electronic paper display 11 and the opposing surface 13A of the light-transmitting panel 13. In this way, the reflected light from the reflective surface 43A of the concave mirror 43 travels along the display surface 11A in the gap S created between the display surface 11A of the electronic paper display 11 and the opposing surface 13A of the light-transmitting panel 13. A portion of the reflected light from the reflective surface 43A is reflected by the opposing surface 13A of the light-transmitting panel 13 and illuminates the display surface 11A of the electronic paper display 11. The image displayed on the display surface 11A is viewed by the user through the light-transmitting panel 13. Since the light-transmitting panel 13 promotes the illumination of light to the display surface 11A of the electronic paper display 11, the efficiency of light utilization is improved. Furthermore, by taking in ambient light through the light-transmitting panel 13, it becomes possible to use ambient light for displaying images.

[0045] Next, in order to verify the advantages of the front light device 12 according to this embodiment, comparative experiment 1 described below was conducted. In comparative experiment 1, a simulation was performed using a computer to irradiate an electronic paper display 11 with the illumination light of each front light device 12,100 according to the following Example 1 and Comparative Example 1, and the angular characteristics and illuminance distribution of the illumination light were obtained. Example 1 is a front light device 12 with the configuration described in the preceding paragraph. Comparative Example 1 is a front light device 100 with the configuration shown in Figure 6, comprising an LED 101, an LED substrate 102 on which the LED 101 is mounted, a lens 103 into which light from the LED 101 is incident, and a housing 104 that houses the LED 101, the LED substrate 102, and the lens 103.

[0046] The configuration of Comparative Example 1 will be explained using Figure 6. The housing 104 has the same configuration as the housing 44 of Example 1, and has a first housing component 104A, a second housing component 104B, a third housing component 104C, and an opening 104D. The LED substrate 102 is mounted on the inner surface of the second housing component 104B. The LED 101 is positioned further from the first end 11E1 of the electronic paper display 11 than the lens 103. The LED 101 is a side-emitting type, and its light-emitting surface 101A faces the opposite side from the third housing component 104C (the right side in Figure 6, the side of the electronic paper display 11). The lens 103 is positioned closer to the first end 11E1 of the electronic paper display 11 than the LED 101. The lens 103 has a light-receiving surface 103A facing the light-receiving surface 101A of the LED 101, and a light-emitting surface 103B facing the gap S side. The lens 103 has a light-receiving surface 103A that is approximately parallel to the light-emitting surface 101A of the LED 101. The light-emitting surface 103B of the lens 103 is aspherical in order to eliminate spherical aberration so that the light emitted from the light-emitting surface 103B becomes parallel light rays. In other words, the lens 103 is a so-called collimating lens. Specifically, the lens 103 is configured such that the light-emitting surface 103B recedes towards the LED 101 (left side of Figure 6) as it moves away from the LED 101 in the Z-axis direction (lower end of Figure 6), and the light-emitting surface 103B protrudes towards the electronic paper display 11 (right side of Figure 6) as it moves closer to the LED 101 in the Z-axis direction (upper end of Figure 6), resulting in an overall convex shape.

[0047] The experimental results of Comparative Experiment 1 are shown in Figures 7 to 10. Figure 7 is a table including a graph showing the angular characteristics of the illumination light of the front light device 100 according to Example 1. Figure 8 is a table including a graph showing the angular characteristics of the illumination light of the front light device 12 according to Comparative Example 1. The table in Figure 8 shows the angular characteristics of the emitted light from three different positions (the first position P1, the second position P2, and the third position P3 shown in Figure 6) on the light-emitting surface 103B of the lens 103 in the Z-axis direction. The first position P1 is located near the upper end of the light-emitting surface 103B in the Z-axis direction, as shown in Figure 6, and is closest to the optical axis AX. The second position P2 is located near the center of the light-emitting surface 103B in the Z-axis direction, and is the second closest to the optical axis AX. The third position P3 is located near the lower end of the light-emitting surface 103B in the Z-axis direction, and is furthest from the optical axis AX. The table in Figure 7 shows the angular characteristics of the reflected light at three different positions (the fourth position P4, the fifth position P5, and the sixth position P6 shown in Figure 5) on the reflective surface 43A of the concave mirror 43, along the Z-axis. The fourth position P4 is located near the upper end of the reflective surface 43A along the Z-axis, as shown in Figure 5, and is the furthest from the optical axis AX. The fifth position P5 is located near the center of the reflective surface 43A along the Z-axis, and is the second closest to the optical axis AX. The sixth position P6 is located near the lower end of the reflective surface 43A along the Z-axis, and is the closest to the optical axis AX.

[0048] In the graphs shown in the tables of Figures 7 and 8, the illumination angle range of the light is indicated by a shaded pattern. In the graphs shown in the tables of Figures 7 and 8, the horizontal axis, indicated by a dashed line, coincides with the Y-axis shown in Figures 5 and 6. In the graphs shown in the tables of Figures 7 and 8, the vertical axis, indicated by a dashed line, coincides with the Z-axis shown in Figures 5 and 6. In the graphs shown in the tables of Figures 7 and 8, the intersection of the horizontal and vertical axes, indicated by the dashed lines, coincides with the optical axis AX of each LED 40,101.

[0049] Figures 9 and 10 show the illuminance distribution within the display surface 11A of an electronic paper display 11, which is the object illuminated by the illumination light from each front light device 12,100 according to Example 1 and Comparative Example 1. The illuminance distributions shown in Figures 9 and 10 were created by simulating the illumination light shining onto the display surface 11A of the electronic paper display 11 with all LEDs 40,101 of each front light device 12,100 lit, and the level of illuminance is represented by shades of gray. Below the illuminance distributions shown in Figures 9 and 10, a legend related to the illuminance distribution is attached. This legend indicates that the higher the illuminance, the lighter the shade (closer to white), and the lower the illuminance, the darker the shade (closer to black). Note that the left edge of the electronic paper display 11 shown in Figures 9 and 10 coincides with the first edge 11E1 adjacent to each front light device 12,100. Figure 9 shows the illuminance distribution of the illumination light of the front light device 100 according to Comparative Example 1. Figure 10 shows the illuminance distribution of the illumination light of the front light device 12 according to Example 1.

[0050] The experimental results of Comparative Experiment 1 will now be explained. According to Figure 8, in Comparative Example 1, at the first position P1, which is closest to the optical axis AX, the parallelism of the illumination light is kept sufficiently high. However, at the second position P2, some of the illumination light traveling left and right in the Y-axis direction relative to the optical axis AX (diagonally in the horizontal direction) travels upward in the Z-axis direction, and at the third position P3, almost all of the illumination light traveling left and right in the Y-axis direction relative to the optical axis AX travels upward in the Z-axis direction. In other words, in Comparative Example 1, the parallelism of the illumination light emitted from the light-emitting surface 103B of the lens 103 tends to deteriorate as the distance from the optical axis AX increases. It is presumed that this is because, in Comparative Example 1, the lens 103, which is an optical component that determines the direction of illumination light propagation, has a loss of parallelism when emitted from the light traveling left and right in the Y-axis direction relative to the optical axis AX, due to the angle of inclination relative to the optical axis AX, resulting in upward propagation in the Z-axis direction. On the other hand, as shown in Figure 7, in Example 1, the parallelism of the illumination light is kept sufficiently high from the 6th position P6, which is closest to the optical axis AX, to the 4th position P4, which is furthest from the optical axis AX. In other words, in Example 1, regardless of the positional relationship with the optical axis AX, the illumination light reflected by the reflective surface 43A of the concave mirror 43 travels with high parallelism. This is presumed to be because, in Example 1, the concave mirror 43, which is the optical component that determines the direction of illumination light propagation, hardly loses its parallelism during reflection, even if the light traveling left and right in the Y-axis direction relative to the optical axis AX is tilted relative to the optical axis AX.

[0051] According to Figure 9, in Comparative Example 1, the illuminance of the display surface 11A of the electronic paper display 11 is remarkably high in the part close to the first end 11E1 (LED 101) in the X-axis direction, and decreases as you move away from that part in the X-axis direction, with the illuminance being lowest in the part furthest from the first end 11E1 (LED 101). In other words, Comparative Example 1 has an uneven illuminance distribution and low brightness uniformity. This is presumed to be due to the fact that in Comparative Example 1, as shown in the experimental results in Figure 8, the illumination light contains a large amount of light traveling upward in the Z-axis direction, and such light is emitted directly to the outside through the light-transmitting panel 13. On the other hand, according to Figure 10, in Example 1, there is almost no difference in illuminance between the part of the display surface 11A of the electronic paper display 11 that is close to the first end 11E1 (LED 40) in the X-axis direction and the part that is far from the first end 11E1 (LED 40). In other words, Example 1 can be said to have almost no unevenness in the illuminance distribution and a sufficiently high degree of brightness uniformity. This is thought to be due to the fact that, as shown in the experimental results in Figure 7, Example 1 contains almost no light traveling upward in the Z-axis direction in the illumination light.

[0052] As described above, the front light device (illumination device) 12 of this embodiment includes an LED (light source) 40 having a light-emitting surface 40A that emits light for illuminating the display surface 11A, which is the main surface to be illuminated of the electronic paper display 11, which is the object to be illuminated, and a concave mirror 43 that is located laterally to the electronic paper display 11, which is the object to be illuminated, and is positioned opposite the light-emitting surface 40A of the LED 40. The concave mirror 43 has a reflective surface 43A configured to cause the reflected light to travel along the display surface 11A, which is the main surface to be illuminated.

[0053] Light emitted from the light-emitting surface 40A of the LED 40 is reflected by the reflective surface 43A of the concave mirror 43, which is located opposite the light-emitting surface 40A and to the side of the electronic paper display 11 that is to be illuminated, and then irradiated onto the display surface 11A, which is the main surface to be illuminated of the electronic paper display 11. The concave mirror 43 is configured so that the light reflected by the reflective surface 43A travels along the display surface 11A, which is the main surface to be illuminated of the electronic paper display 11 that is to be illuminated, thus mitigating any difference in the amount of irradiated light that may occur between the part of the display surface 11A that is close to the concave mirror 43 and the part that is far from the concave mirror 43. In particular, compared to the conventional method using a Fresnel lens, the reflected light from the reflective surface 43A of the concave mirror 43 maintains its parallelism even when it is far from the optical axis AX of the LED 40. As a result, more light can be irradiated onto the part of the display surface 11A, which is the main surface to be illuminated, that is farther from the concave mirror 43, and light that is emitted to the outside without being irradiated onto the display surface 11A, which is the main surface to be illuminated, near the concave mirror 43 can be suppressed. This improves the uniformity of brightness within the display surface 11A, which is the main surface to be illuminated, of the electronic paper display 11, which is the object to be illuminated.

[0054] Furthermore, a reflective sheet (reflective material) 42 extends from the LED 40 to the concave mirror 43 and reflects light. A portion of the light emitted from the light-emitting surface 40A of the LED 40 can be reflected by the reflective sheet 42 before reaching the reflective surface 43A of the concave mirror 43. This improves the efficiency of light utilization.

[0055] Furthermore, the display device 10 according to this embodiment comprises the front light device 12 described above and an electronic paper display (display panel) 11 that displays using light from the LED 40. The electronic paper display 11 is the illuminated object and has a display surface 11A on which an image is displayed as the main surface to be illuminated. With such a display device 10, the light emitted from the light-emitting surface 40A of the LED 40 is reflected by the reflective surface 43A of the concave mirror 43 and then irradiated onto the display surface 11A of the electronic paper display 11, and used to display an image on the display surface 11A. Since the uniformity of brightness on the display surface 11A of the electronic paper display 11 is improved, excellent display quality can be obtained.

[0056] Furthermore, the LED 40 and the concave mirror 43 are positioned laterally to the first end 11E1, which is included in the outer edge of the electronic paper display 11, and the LED 40 is positioned closer to the first end 11E1 than the concave mirror 43. The light emitted from the light-emitting surface 40A of the LED 40, which is positioned closer to the first end 11E1 of the electronic paper display 11 than the concave mirror 43, is reflected by the reflective surface 43A of the concave mirror 43, which is positioned further from the first end 11E1 than the LED 40, before being irradiated onto the display surface 11A.

[0057] Furthermore, the electronic paper display 11 is equipped with a translucent panel 13 having an opposing surface 13A facing the display surface 11A, with a gap S between the display surface 11A and the opposing surface 13A, and the concave mirror 43 is positioned so that its reflective surface 43A faces the gap S. The reflected light from the reflective surface 43A of the concave mirror 43 travels along the display surface 11A in the gap S between the display surface 11A of the electronic paper display 11 and the opposing surface 13A of the translucent panel 13. A portion of the reflected light from the reflective surface 43A is reflected by the opposing surface 13A of the translucent panel 13 and illuminates the display surface 11A of the electronic paper display 11. The image displayed on the display surface 11A is viewed by the user through the translucent panel 13. Since the translucent panel 13 promotes the illumination of light to the display surface 11A of the electronic paper display 11, the efficiency of light utilization is improved. Furthermore, by taking in ambient light through the light-transmitting panel 13, it becomes possible to use ambient light for displaying images.

[0058] Furthermore, the display panel is an electronic paper display 11. By utilizing the light irradiated onto the display surface 11A, an image can be displayed on the display surface 11A of the electronic paper display 11.

[0059] <Embodiment 2> Embodiment 2 will be described with reference to Figures 11 to 16. This Embodiment 2 shows the case in which a specular reflective material 45 is added. Note that redundant explanations of the structure, operation, and effects, which are the same as those described in Embodiment 1, will be omitted.

[0060] As shown in Figures 11 to 13, the front light device 112 according to this embodiment includes a specular reflective material 45 that is arranged to fill the gap S between the electronic paper display 111 and the light-transmitting panel 113. The specular reflective material 45, like the reflective sheet 142, specularly reflects light through its surface and is in the form of a film or plate. The specular reflective material 45 is arranged such that the reflective surface 45A that specularly reflects light is substantially perpendicular to the display surface 111A of the electronic paper display 111. The specular reflective material 45 is positioned laterally to the second end 111E2 of the outer periphery of the electronic paper display 111, where the LED 140 and concave mirror 143 are not located. In this embodiment, the electronic paper display 111 is rectangular in shape and includes one first end 111E1 and three second ends 111E2 at its outer periphery. Accordingly, the front light device 112 according to this embodiment includes a total of three specular reflectors 45, each positioned laterally to each of the three second ends 111E2. The specular reflectors 45 have a length dimension that extends along the entire length of the corresponding second end 111E2 and a width dimension that is greater than the thickness of the gap S between the electronic paper display 111 and the light-transmitting panel 113. The specular reflectors 45 are positioned adjacent to the corresponding second end 111E2, thereby largely filling the gap S between the electronic paper display 111 and the light-transmitting panel 113. The gap S between the electronic paper display 111 and the light-transmitting panel 113 is surrounded all around by the housing 144 and the three specular reflectors 45 that constitute the front light device 112. The specular reflective material 45 has its reflective surface 45A exposed in the gap S between the electronic paper display 111 and the light-transmitting panel 113.

[0061] With this configuration, when light reflected by the reflective surface 143A of the concave mirror 143 passes beyond the first end 111E1 and enters the gap S, much of it illuminates the display surface 111A, but some of it does not directly illuminate the display surface 111A and passes beyond the second end 111E2 of the electronic paper display 111. When the light that has passed beyond the second end 111E2 reaches the specular reflecting material 45 positioned laterally to the second end 111E2, it is specularly reflected there, and again passes beyond the second end 111E2 and enters the gap S, and much of it illuminates the display surface 111A. As a result, the efficiency of light utilization can be improved and the brightness of the image displayed on the display surface 111A can be increased. Furthermore, since the specular reflecting material 45 is designed to reflect light specularly, the reflected light from the specular reflecting material 45 is easily evenly illuminated to both the part of the display surface 111A that is close to the specular reflecting material 45 and the part that is far from the specular reflecting material 45, making it less likely for differences in the amount of illuminated light to occur. As a result, the uniformity of brightness on the display surface 111A of the electronic paper display 111 can be improved.

[0062] The specular reflective material 45 positioned on the outside of the second end 111E2, which is located on the opposite side of the first end 111E1 (right side in Figures 11 and 12) of the outer peripheral edge of the electronic paper display 111, is positioned facing the concave mirror 143, and its reflective surface 45A faces the reflective surface 143A across an air gap S. Therefore, a portion of the light reflected by the reflective surface 143A of the concave mirror 143 travels along the display surface 111A, and once it passes the second end 111E2, which is located on the opposite side of the first end 111E1, it is specularly reflected by the reflective surface 45A of the specular reflective material 45 positioned there. In addition, the two specular reflective materials 45 positioned on the outside of the remaining two second ends 111E2 of the outer peripheral edge of the electronic paper display 111 are positioned on both sides of the concave mirror 143, and their reflective surfaces 45A face each other across an air gap S. Therefore, a portion of the light reflected by the reflective surface 143A of the concave mirror 143 travels along the display surface 111A and spreads out on both sides in the Y-axis direction. Once it passes the two second ends 111E2 described above, it is specularly reflected by the two specular reflectors 45 positioned there. As a result, the efficiency of light utilization can be further improved, and the brightness of the image displayed on the display surface 111A becomes higher.

[0063] Next, to verify the advantages of the front light device 112 according to this embodiment, comparative experiment 2 was conducted as described below. In comparative experiment 2, a computer was used to simulate irradiating an electronic paper display 111 with the illumination light of each front light device 112 according to the following Example 2, Comparative Example 2, and Comparative Example 3, and the illuminance distribution related to the illumination light was obtained. Example 2 is a front light device 112 with the configuration described in the preceding paragraph. Comparative Example 2, although not shown in the figures, has a configuration in which three specular reflective materials 45 are added to Comparative Example 1 of Comparative Experiment 1 described in Embodiment 1, similar to Example 2. Comparative Example 3, although not shown in the figures, has a configuration in which a diffuse reflective material that diffusely reflects light is used instead of the specular reflective material 45 provided in Example 2.

[0064] The experimental results of Comparative Experiment 1 are shown in Figures 14 to 16. Figures 14 to 16 show the illuminance distribution within the display surface 111A of the electronic paper display 111, which is the object illuminated by the illumination light of each front light device 112 according to Example 2, Comparative Example 2, and Comparative Example 3. The illuminance distributions shown in Figures 14 to 16 were created in the same manner as the illuminance distributions explained in Comparative Experiment 1 (see Figures 9 and 10), and the levels of illuminance are represented by the shades shown in the legend. A legend relating to the illuminance distribution is attached below the illuminance distributions shown in Figures 14 to 16. Note that the left end of the electronic paper display 111 shown in Figures 14 to 16 coincides with the first end 111E1 adjacent to each front light device 112, and the remaining ends coincide with the second end 111E2 adjacent to each specular reflector 45 or each diffuse reflector. Figure 14 shows the illuminance distribution of the illumination light of the front light device according to Comparative Example 2. Figure 15 shows the illuminance distribution of the illumination light of the front light device according to Comparative Example 3. Figure 16 shows the illuminance distribution of the illumination light of the front light device 112 according to Example 2.

[0065] The experimental results of Comparative Experiment 1 will now be explained. According to Figure 14, Comparative Example 2 shows an increased amount of light irradiated onto the display surface 111A of the electronic paper display 111 compared to the experimental results of Comparative Example 1 shown in Figure 9. However, Comparative Example 2 still shows uneven illuminance distribution and low brightness uniformity compared to the experimental results of Example 1 shown in Figure 10. This is thought to be due to the fact that in Comparative Example 2, although the light utilization efficiency is improved due to the specular reflection of light by the specular reflective material 45, the amount of light directed directly towards the light-transmitting panel 113 near the first end 111E1 is remarkably high due to the lens 103 (see Figure 6). According to Figure 15, in Comparative Example 3, compared to Comparative Example 2, there is almost no difference in illuminance between the part of the display surface 111A of the electronic paper display 111 that is close to the first end 111E1 and the part that is far from the first end 111E1 in the X-axis direction. However, the amount of light is remarkably high near the three second edges 111E2 of the display surface 111A of the electronic paper display 111. This is thought to be because, although the uniformity of brightness is high in Comparative Example 3 due to the presence of a concave mirror, the light is diffusely reflected by each diffuse reflecting material placed adjacent to each second edge 111E2, causing the reflected light to be biased towards the vicinity of each second edge 111E2.

[0066] On the other hand, as shown in Figure 16, Example 2 achieves a similar level of uniformity in illuminance distribution compared to the experimental results of Example 1 shown in Figure 10, while also increasing the amount of light irradiated onto the display surface 111A of the electronic paper display 111. This suggests that in Example 2, the light utilization efficiency is improved due to the specular reflection of light by the specular reflecting material 45. Compared to the experimental results of Comparative Example 3 shown in Figure 16, Example 2 shows a similar level of light intensity near the three second ends 111E2 of the display surface 111A of the electronic paper display 111, as it does in other areas. In other words, Example 2 has a higher level of uniformity in illuminance distribution and a sufficiently higher level of brightness uniformity than Comparative Example 3. This suggests that in Example 3, the light specularly reflected by the specular reflecting material 45 adjacent to the second ends 111E2 is less likely to be biased towards irradiating the vicinity of the second ends 111E2 of the display surface 111A.

[0067] As described above, according to this embodiment, the electronic paper display 111 is equipped with a specular reflecting material 45 that is positioned laterally to the second end 111E2 of the outer peripheral edge of the electronic paper display 111, where the LED 140 and concave mirror 143 are not located, and which specularly reflects light. Of the light reflected by the reflective surface 143A of the concave mirror 143, the light that does not directly irradiate the display surface 111A reaches the specular reflecting material 45 positioned laterally to the second end 111E2 of the electronic paper display 111, where it is specularly reflected and irradiates the display surface 111A. This improves the efficiency of light utilization and increases the brightness of the image displayed on the display surface 111A. Moreover, if a diffuse reflecting material that diffusely reflects light were used instead of the specular reflecting material 45, the light diffusely reflected by the diffuse reflecting material would tend to be biased towards the vicinity of the second end 111E2 of the display surface 111A. In contrast, the light specularly reflected by the specular reflecting material 45 is less likely to be biased towards the vicinity of the second end 111E2 of the display surface 111A. This improves the uniformity of brightness on the display surface 111A of the electronic paper display 111.

[0068] Furthermore, the electronic paper display 111 is rectangular in shape and includes one first end 111E1 and three second ends 111E2 at its outer periphery, with the specular reflector 45 positioned laterally to each of the three second ends 111E2. The specular reflector 45 positioned outward from the second end 111E2, which is on the opposite side of the first end 111E1, is positioned in front of the concave mirror 143. Therefore, a portion of the light reflected by the reflective surface 143A of the concave mirror 143 travels along the display surface 111A, and once it passes the second end 111E2, which is on the opposite side of the first end 111E1, it is specularly reflected by the specular reflector 45 positioned there. Furthermore, the two specular reflectors 45, which are positioned on the outside of the remaining two second ends 111E2 of the outer edge of the electronic paper display 111, are positioned on both sides of the concave mirror 143. Therefore, a portion of the light reflected by the reflective surface 143A of the concave mirror 143 travels along the display surface 111A and spreads to both sides, and once it passes the two second ends 111E2 mentioned above, it is specularly reflected by the two specular reflectors 45 positioned there. As a result, the efficiency of light utilization can be further improved, and the brightness of the image displayed on the display surface 111A can be increased.

[0069] <Embodiment 3> Embodiment 3 will be described with reference to Figures 17 to 23. This Embodiment 3 shows a case in which louvers 46 are added to Embodiment 2 described above, and the number of electronic paper displays 211, etc., is changed. Note that redundant explanations of the structure, operation, and effects, which are the same as those of Embodiment 2 described above, will be omitted.

[0070] As shown in Figure 17, the front light device 212 according to this embodiment has two electronic paper displays 211 and two housings 244. The two electronic paper displays 211 are arranged side by side along the Y-axis, with one end (the third end 211E3 described below) extending along the X-axis facing each other. The outer peripheral end of the electronic paper display 211 according to this embodiment includes one first end 211E1 on which an LED 240, LED substrate 241, reflective sheet 242, concave mirror 243, and housing 244 are arranged laterally, two second ends 211E2 on which a specular reflective material 245 is arranged laterally, and one third end 211E3 on which the LED 240, LED substrate 241, reflective sheet 242, concave mirror 243, housing 244, and specular reflective material 245 are not arranged. The first end 211E1 is the left end of the outer periphery of each electronic paper display 211 as shown in Figure 17. The two second ends 211E2 are the right end of the outer periphery of each electronic paper display 211 as shown in Figure 17 and the end opposite to the third end 211E3 described below. The third end 211E3 is the mutually opposing ends of the outer periphery of the two electronic paper displays 211. The light-transmitting panel 213 is sized to span across the two electronic paper displays 211 (for example, about A1 size).

[0071] As shown in Figure 17, the two housings 244 are arranged side by side along the Y-axis and are positioned laterally to each of the first ends 211E1 of the two electronic paper displays 211. Each housing 244 contains two LED boards 241, a reflective sheet 242, and a concave mirror 243. The four LED boards 241 housed in the two housings 244 are arranged side by side along the Y-axis, and the multiple LEDs 240 mounted on each are arranged in a straight line to form a single row. The four reflective sheets 242 and four concave mirrors 243 housed in the two housings 244 are also arranged side by side along the Y-axis.

[0072] In the following, when distinguishing between the two electronic paper displays 211, the electronic paper display 211 located on the upper side of Figure 17 will be referred to as the "first electronic paper display (first display panel)" and its reference numeral will be denoted with the subscript α, and the electronic paper display 211 located on the lower side of Figure 17 will be referred to as the "second electronic paper display (second display panel)" and its reference numeral will be denoted with the subscript β. When referring to them collectively without distinction, no subscript will be added to the reference numeral.

[0073] As shown in Figure 17, the first electronic paper display 211α and the second electronic paper display 211β are arranged side by side such that their third ends 211E3 are close together or in contact with each other with a small gap between them. The specular reflector 245 includes a portion arranged to the side of the second end 211E2 of the outer peripheral edge of the first electronic paper display 211α that extends along the X-axis direction, a portion arranged to the side of the second end 211E2 of the outer peripheral edge of the second electronic paper display 211β that extends along the X-axis direction, and a portion arranged to the side of each second end 211E2 of the outer peripheral edges of the first electronic paper display 211α and the second electronic paper display 211β that extends along the Y-axis direction. Of these, the specular reflector 245 extending along the Y-axis direction has a length dimension that spans both the first electronic paper display 211α and the second electronic paper display 211β.

[0074] According to this embodiment, images are displayed on the display surfaces 211A of the first electronic paper display 211α and the second electronic paper display 211β, which are arranged so that their respective third ends 211E3 are aligned, thereby enabling a screen size approximately twice that of Embodiment 2. Specifically, the display area AA has a long side dimension of approximately 836 mm and a short side dimension of approximately 592 mm. Furthermore, since specular reflective materials 245 are arranged laterally to each of the two second ends 211E2 of the first electronic paper display 211α and the second electronic paper display 211β, the efficiency of light utilization can be improved.

[0075] As shown in Figures 17 and 18, the front light device 212 according to this embodiment includes a louver 46 positioned between the housing 244 and the electronic paper display 211. Specifically, the louver 46 is positioned laterally to the first end 211E1 of the outer peripheral edge of the electronic paper display 211 and is positioned closer to the first end 211E1 than to the housing 244. The louver 46 is designed to regulate the emission angle range of light emitted from the opening 244D of the housing 244 and is in the shape of an elongated sheet extending along the Y-axis. The main surface of the louver 46 is positioned substantially perpendicular to the display surface 211A of the electronic paper display 211 and opposite to the reflective surface 243A of the concave mirror 243. Two louvers 46 are positioned laterally to each of the two first ends 211E1 of the electronic paper displays 211. The two louvers 46 are positioned side by side along the Y-axis. The louvers 46 have a length dimension that extends along the entire length of the adjacent housing 244, and a width dimension that is greater than the thickness of the gap S between the electronic paper display 211 and the light-transmitting panel 213 (the opening width of the opening 244D). As shown in Figures 17 to 19, three specular reflective materials 245, as described in Embodiment 2, are arranged on the sides of three second ends 211E2 of the outer peripheral edge of the electronic paper display 211.

[0076] As shown in Figure 20, the louver 46 has a pair of base materials 46A and 46B, a light-shielding portion 46C sandwiched between the pair of base materials 46A and 46B, and a light-transmitting portion 46D sandwiched between the pair of base materials 46A and 46B. The pair of base materials 46A and 46B include a first base material 46A located on the housing 244 side (left side in Figure 20) and a second base material 46B located on the electronic paper display 211 side (right side in Figure 20). Both the first base material 46A and the second base material 46B are made of a synthetic resin material or the like that is almost transparent and has excellent light transmission properties.

[0077] As shown in Figure 20, the light-shielding portion 46C is made of a light-shielding resin material (light-shielding material) that is, for example, black in color and blocks light. The light-shielding portion 46C is layered and extends along the X-axis and Y-axis directions, and multiple portions are arranged side by side with spacing in the Z-axis direction (normal direction to the display surface 211A). The light-transmitting portion 46D is made of a light-transmitting resin material (light-transmitting material) that is almost transparent and transmits light, or an air layer. The light-transmitting portion 46D is layered and extends along the X-axis and Y-axis directions, and multiple portions are arranged side by side with spacing in the Z-axis direction. All of the multiple light-transmitting portions 46D are positioned such that their positions in the Z-axis direction are within the formation range of the opening 244D and the gap S. As a result, light from the opening 244D enters each light-transmitting portion 46D, and the light that enters each light-transmitting portion 46D is emitted out into the gap S. Multiple light-shielding sections 46C and light-transmitting sections 46D are arranged alternately in a repeating pattern along the Z-axis. Therefore, a light-transmitting section 46D is interposed between two adjacent light-shielding sections 46C that are spaced apart along the Z-axis, and a light-shielding section 46C is interposed between two adjacent light-transmitting sections 46D that are spaced apart along the Z-axis. Light that passes through the first substrate 46A of the louver 46 through the opening 244D of the housing 244 passes through the light-transmitting section 46D arranged between two adjacent light-shielding sections 46C in the Z-axis direction, and then passes through the second substrate 46B. The emission angle of the light emitted from the second substrate 46B in the Z-axis direction is limited by two adjacent light-shielding sections 46C in the Z-axis direction.

[0078] Here, as shown in Figure 20, the LED 240 in the front light device 212 is a side-emitting type, and is designed so that all light is emitted from the light-emitting surface 240A facing the concave mirror 243. However, in reality, light may leak from the top surface (top surface) 240B of the LED 240, which is the surface facing the second housing component 244B. Such leaked light L does not travel from the top surface 240B towards the concave mirror 243, but may directly illuminate the light-transmitting panel 213. This leaked light L travels along an oblique direction that forms an angle greater than or equal to the optical axis AX (X-axis direction) of the LED 240, and does not travel along the display surface 211A. Therefore, when leaked light L is emitted from the top surface 240B of the LED 240, most of the leaked light L cannot pass through the light-transmitting portion 46D of the louver 46 and is absorbed by the light-shielding portion 46C. This prevents the light emitted from the LED 240 from directly shining on the light-transmitting panel 213, thereby improving the uniformity of brightness within the display surface 211A of the electronic paper display 211.

[0079] Next, in order to verify the advantages of the front light device 212 according to this embodiment, the following demonstration experiment 1 was conducted. In demonstration experiment 1, the illumination light of the front light device 212 according to the following embodiment 3 was irradiated onto the electronic paper display 211, and the luminance distribution related to the illumination light was obtained. Embodiment 3 is the front light device 212 with the configuration described in the preceding paragraph. The experimental results of demonstration experiment 1 are shown in Figures 21 to 23. Figure 21 shows the luminance distribution within the surface of the display surface 211A of the electronic paper display 211, which is the object irradiated with the illumination light of the front light device 212 according to embodiment 3. The illuminance distribution shown in Figure 21 was created by irradiating the display surface 211A of the electronic paper display 211 with illumination light while all LEDs 240 provided in the front light device 212 were lit, and measuring the luminance related to the emitted light from the display surface 211A, with the high and low levels of luminance represented by shades of gray. Below the luminance distribution shown in Figure 21, a legend relating to the luminance distribution is attached. This legend indicates that higher luminance results in lighter shades (closer to white), and lower luminance results in darker shades (closer to black). Note that the left edge of the electronic paper display 211 shown in Figure 21 coincides with the first edge 211E1 adjacent to the front light device 212. Furthermore, the luminance distribution of the first electronic paper display 211α is shown at the top of Figure 21, and the luminance distribution of the second electronic paper display 211β is shown at the bottom of Figure 21.

[0080] Figure 22 shows a graph relating to the luminance distribution in the X-axis direction for the first electronic paper display 211α. Figure 23 shows a graph relating to the luminance distribution in the X-axis direction for the second electronic paper display 211β. The graphs in Figures 22 and 23 show the luminance distribution in the X-axis direction at the central position in the Y-axis direction for each electronic paper display 211α and 211β. The vertical axis in Figures 22 and 23 represents luminance. The horizontal axis in Figures 22 and 23 represents the position in the X-axis direction, with the left end of the horizontal axis coinciding with the first end 211E1 of each electronic paper display 211α and 211β, and the right end of the horizontal axis coinciding with the second end 211E2, which is opposite to the first end 211E1 of each electronic paper display 211α and 211β.

[0081] The experimental results of Demonstration Experiment 1 will now be explained. As shown in Figures 21 to 23, there is almost no difference in illuminance between the part of each display surface 211A of each electronic paper display 211α and 211β that is close to the first end 211E1 in the X-axis direction and the part that is far from the first end 211E1. In particular, there is almost no localized high-luminance region observed near the first end 211E1 in the X-axis direction of each display surface 211A of each electronic paper display 211α and 211β. This is presumed to be because the leaked light L emitted from the top surface 240B of the LED 240 is well blocked by the light-shielding part 46C of the louver 46. Furthermore, there is no difference in magnitude in the luminance distribution between the first electronic paper display 211α and the second electronic paper display 211β. As described above, it can be said that Example 3 has almost no unevenness in the luminance distribution and has a sufficiently high degree of uniformity in luminance.

[0082] As described above, according to this embodiment, a louver 46 is provided which is located laterally to the electronic paper display 211, which is the object to be irradiated, and is positioned opposite the reflective surface 243A. The louver 46 has two light-shielding parts 46C which are spaced apart in the direction normal to the display surface 211A, which is the main surface to be irradiated, and a light-transmitting part 46D which is positioned between the two light-shielding parts 46C. When the reflected light from the reflective surface 243A reaches the louver 46 which is positioned laterally to the electronic paper display 211, which is the object to be irradiated, it passes through the light-transmitting part 46D positioned between the two light-shielding parts 46C and then irradiates the display surface 211A, which is the main surface to be irradiated of the electronic paper display 211. Even if the reflected light from the reflective surface 243A includes light that does not travel along the display surface 211A, which is the main surface to be illuminated (leaked light L), this light is blocked by the light-shielding portion 46C. This makes it possible to further improve the uniformity of brightness within the display surface 211A, which is the main surface to be illuminated of the electronic paper display 211, which is the illuminated object.

[0083] Furthermore, the electronic paper display 211 is rectangular in shape and includes one third end 211E3, one first end 211E1, and two second ends 211E2 at its outer edge, where the LED 240, concave mirror 243, and specular reflector 245 are not positioned. The electronic paper display 211 includes a first electronic paper display (first display panel) 211α and a second electronic paper display (second display panel) 211β, which are arranged so that their respective third ends 211E3 are aligned. The specular reflector 245 is positioned laterally to each of the two second ends 211E2 provided on the first electronic paper display 211α and the second electronic paper display 211β. By displaying images on the respective display surfaces 211A of the first electronic paper display 211α and the second electronic paper display 211β, which are arranged so that their respective third ends 211E3 are aligned, a larger screen size can be achieved. Furthermore, since specular reflectors 245 are provided laterally to each of the two second ends 211E2 of the first electronic paper display 211α and the second electronic paper display 211β, the efficiency of light utilization can be improved.

[0084] <Embodiment 4> Embodiment 4 will be described with reference to Figures 24 to 26. This Embodiment 4 shows a case where the number of electronic paper displays 311, etc., installed is changed from Embodiment 3 described above. Note that redundant explanations of the structure, operation, and effects, which are the same as those of Embodiment 3 described above, will be omitted.

[0085] As shown in Figure 24, the front light device 312 according to this embodiment has four electronic paper displays 311, four housings 344, and four louvers 346. The four electronic paper displays 311 are arranged in a grid pattern, with one end extending along the X-axis (one of the third ends 311E3A described below) facing each other, and one end extending along the Y-axis (the other third end 311E3B described below) facing each other. The outer periphery of the electronic paper display 311 according to this embodiment includes one first end 311E1 on which an LED 340, LED substrate 341, reflective sheet 342, concave mirror 343, and housing 344 are arranged laterally, one second end 311E2 on which a specular reflective material 345 is arranged laterally, and two third ends 311E3 on which the LED 340, LED substrate 341, reflective sheet 342, concave mirror 343, housing 344, and specular reflective material 345 are not arranged. The first end 311E1 is the outer periphery of each electronic paper display 311 opposite to the other third end 311E3B described below. The second end 311E2 is the outer periphery of each electronic paper display 311 opposite to the one third end 311E3A described below. The two third ends 311E3 are opposing ends of the outer periphery of the four electronic paper displays 311, and include one third end 311E3A extending along the X-axis and the other third end 311E3B extending along the Y-axis. The light-transmitting panel 313 is sized to span across the four electronic paper displays 311 (for example, about A0 size).

[0086] In the following, when distinguishing between the four electronic paper displays 311, the electronic paper display 311 located in the upper left of Figure 24 will be referred to as the "first electronic paper display (first display panel)" and its designation will be denoted with the subscript α; the electronic paper display 311 located in the lower left of Figure 24 will be referred to as the "second electronic paper display (second display panel)" and its designation will be denoted with the subscript β; the electronic paper display 311 located in the upper right of Figure 24 will be referred to as the "third electronic paper display (third display panel)" and its designation will be denoted with the subscript γ; and the electronic paper display 311 located in the lower right of Figure 24 will be referred to as the "fourth electronic paper display (fourth display panel)" and its designation will be denoted with the subscript δ. When referring to them collectively without distinction, no subscripts will be added to their designations.

[0087] As shown in Figure 24, the four housings 344 and louvers 346 are positioned laterally to each of the four first ends 311E1 of the four electronic paper displays 311. Each of the four housings 344 houses two LED substrates 341, a reflective sheet 342, and a concave mirror 343. The four LED substrates 341 housed in the two housings 344 positioned laterally to each of the first ends 311E1 of the first electronic paper display 311α and the second electronic paper display 311β are aligned along the Y-axis, and the multiple LEDs 340 mounted on each are arranged in a straight line to form a single row. Similarly, the four LED substrates 341 housed in two housings 344 located laterally to the respective first ends 311E1 of the third electronic paper display 311γ and the fourth electronic paper display 311δ are aligned along the Y-axis, and the multiple LEDs 340 mounted on each are arranged in a straight line to form a single row. The four louvers 346 are positioned between the four housings 344 and the respective first ends 311E1 of the four electronic paper displays 311.

[0088] As shown in Figures 24 to 26, the first electronic paper display 311α, the second electronic paper display 311β, the third electronic paper display 311γ, and the fourth electronic paper display 311δ are arranged side by side with their third ends 311E3 close together or in contact with each other, with only a small gap between them. The specular reflector 345 includes those arranged to the sides of the second ends 311E2 of the first electronic paper display 311α and the third electronic paper display 311γ, and those arranged to the sides of the second ends 311E2 of the second electronic paper display 311β and the fourth electronic paper display 311δ. Of these, the specular reflective material 345 arranged on the sides of the second end 311E2 of the first electronic paper display 311α and the third electronic paper display 311γ has a length dimension that spans both the first electronic paper display 311α and the third electronic paper display 311γ. The specular reflective material 345 arranged on the sides of the second end 311E2 of the second electronic paper display 311β and the fourth electronic paper display 311δ has a length dimension that spans both the second electronic paper display 311β and the fourth electronic paper display 311δ.

[0089] According to this embodiment, images are displayed on each display surface 311A ​​of the first electronic paper display 311α, second electronic paper display 311β, third electronic paper display 311γ, and fourth electronic paper display 311δ, which are arranged so that their respective third ends 311E3 are aligned, thereby enabling a screen size approximately twice that of Embodiment 3. Specifically, the display area AA has a long side dimension of approximately 1184 mm and a short side dimension of approximately 836 mm. Furthermore, since a specular reflective material 345 is provided on the outside of each of the second ends 311E2 of the first electronic paper display 311α, second electronic paper display 311β, third electronic paper display 311γ, and fourth electronic paper display 311δ, the efficiency of light utilization can be improved.

[0090] As described above, according to this embodiment, the electronic paper display 311 is rectangular and includes two third ends 311E3, one first end 311E1, and one second end 311E2 at its outer periphery, where the LED 340, concave mirror 343, and specular reflector 345 are not positioned. The electronic paper display 311 includes a first electronic paper display (first display panel) 311α, a second electronic paper display (second display panel) 311β, a third electronic paper display (third display panel) 311γ, and a fourth electronic paper display (fourth display panel) 311δ. The first electronic paper display 311α and the second electronic paper display 311β are arranged so that one of their third ends 311E3A is aligned. The electronic paper displays are arranged such that the third electronic paper display 311γ and the fourth electronic paper display 311δ have one third end 311E3A of each side, the first electronic paper display 311α and the third electronic paper display 311γ have their other third end 311E3B of each side, and the second electronic paper display 311β and the fourth electronic paper display 311δ have their other third end 311E3B of each side. The specular reflector 345 is positioned laterally to each of the two second ends 311E2 of the first electronic paper display 311α, the second electronic paper display 311β, the third electronic paper display 311γ, and the fourth electronic paper display 311δ. The first electronic paper display 311α, the second electronic paper display 311β, the third electronic paper display 311γ, and the fourth electronic paper display 311δ are arranged so that their respective third ends 311E3 are aligned, allowing for a larger screen size. Furthermore, since a specular reflector 345 is provided on the outside of each of the second ends 311E2 of the first electronic paper display 311α, the second electronic paper display 311β, the third electronic paper display 311γ, and the fourth electronic paper display 311δ, the efficiency of light utilization can be improved.

[0091] <Embodiment 5> Embodiment 5 will be described with reference to Figure 27 or Figure 28. This Embodiment 5 shows a case where the number of electronic paper displays 411, etc., installed is changed from Embodiment 3 described above. Note that redundant explanations of the structure, operation, and effects, which are the same as those of Embodiment 3 described above, will be omitted.

[0092] As shown in Figure 27, the front light device 412 according to this embodiment has six electronic paper displays 411, six housings 444, and six louvers 446. The six electronic paper displays 411 are arranged in pairs along the X-axis and three along the Y-axis, with one end of each display facing the other along the X-axis and one end of each display facing the other along the Y-axis. The light-transmitting panel 413 is sized to span across the six electronic paper displays 411.

[0093] In the following, when distinguishing between the six electronic paper displays 411, the electronic paper display 411 located in the upper left of Figure 27 will be designated as the "first electronic paper display (first display panel)" and its designation will be denoted by the subscript α, the electronic paper display 411 located in the upper right of Figure 27 will be designated as the "second electronic paper display (second display panel)" and its designation will be denoted by the subscript β, and the electronic paper display 411 located in the lower left of Figure 27 will be designated as the "third electronic paper display (third display panel)" and its designation will be denoted by the subscript γ. The electronic paper display 411 located in the lower right of Figure 27 is designated as the "fourth electronic paper display (fourth display panel)" and its designation is denoted by the subscript δ; the electronic paper display 411 located in the left center of Figure 27 is designated as the "fifth electronic paper display (fifth display panel)" and its designation is denoted by the subscript ε; and the electronic paper display 411 located in the right center of Figure 27 is designated as the "sixth electronic paper display (sixth display panel)" and its designation is denoted by the subscript ζ. When referring to them collectively without distinction, no subscript is added to the designation.

[0094] Of the six electronic paper displays 411, the outer edges of the first electronic paper display 411α, the second electronic paper display 411β, the third electronic paper display 411γ, and the fourth electronic paper display 411δ include, as shown in Figure 27, one first end 411E1 on the side of which an LED 440, an LED substrate 441, a reflective sheet 442, a concave mirror 443, and a housing 444; one second end 411E2 on the side of which a specular reflective material 445 is arranged; and two third ends 411E3 on which the LED 440, LED substrate 441, reflective sheet 442, concave mirror 443, housing 444, and specular reflective material 445 are not arranged. The first end 411E1 of the first electronic paper display 411α, the second electronic paper display 411β, the third electronic paper display 411γ, and the fourth electronic paper display 411δ is the end of the outer periphery of each electronic paper display 411 opposite to the other third end 411E3A described below. The second end 411E2 of the first electronic paper display 411α, the second electronic paper display 411β, the third electronic paper display 411γ, and the fourth electronic paper display 411δ is the end of the outer periphery of each electronic paper display 411 opposite to the other third end 411E3B described below. The first electronic paper display 411α, the second electronic paper display 411β, the third electronic paper display 411γ, and the fourth electronic paper display 411δ each have two third ends 411E3, one of which is a third end 411E3A that extends along the Y-axis and the other third end 411E3B that extends along the X-axis.

[0095] Of the six electronic paper displays 411, the outer periphery of the fifth electronic paper display 411ε and the sixth electronic paper display 411ζ includes one first end 411E1 on which an LED 440, LED substrate 441, reflective sheet 442, concave mirror 443, and housing 444 are arranged laterally, and three third ends 411E3 on which the LED 440, LED substrate 441, reflective sheet 442, concave mirror 443, housing 444, and specular reflector 445 are not arranged. The first end 411E1 of the fifth electronic paper display 411ε and the sixth electronic paper display 411ζ is the end on the outer periphery of each electronic paper display 411 opposite to the first third end 411E3C described below. The three third ends 411E3 of the fifth electronic paper display 411ε and the sixth electronic paper display 411ζ include a first third end 411E3C extending along the Y-axis, and a second third end 411E3D and a third third end 411E3E extending along the X-axis.

[0096] As shown in Figure 27, the six housings 444 and louvers 446 are positioned laterally to each of the six first ends 411E1 of the electronic paper displays 411. Each of the six housings 444 contains two LED substrates 441, a reflective sheet 442, and a concave mirror 443. The six LED substrates 441 housed in the three housings 444, which are positioned laterally to each of the first ends 411E1 of the first electronic paper display 411α, the third electronic paper display 411γ, and the fifth electronic paper display 411ε, are aligned along the Y-axis, and the multiple LEDs 440 mounted on each are arranged in a straight line to form a single row. Similarly, the six LED substrates 441 housed in three housings 444 located laterally to the first ends 411E1 of the second electronic paper display 411β, the fourth electronic paper display 411δ, and the sixth electronic paper display 411ζ are aligned along the Y-axis, and the multiple LEDs 440 mounted on each are arranged in a straight line to form a single row. The six louvers 446 are positioned between the six housings 444 and the first ends 411E1 of the six electronic paper displays 411.

[0097] The first electronic paper display 411α, the second electronic paper display 411β, the third electronic paper display 411γ, the fourth electronic paper display 411δ, the fifth electronic paper display 411ε, and the sixth electronic paper display 411ζ are arranged side by side, as shown in Figure 27, with their third ends 411E3 close together or in contact with each other with a small gap between them. Specifically, the first electronic paper display 411α and the second electronic paper display 411β are arranged side by side so that one of their third ends 411E3A extending along the Y-axis direction faces the other. The third electronic paper display 411γ and the fourth electronic paper display 411δ are arranged side by side so that one of their third ends 411E3A extending along the Y-axis direction faces the other. The fifth electronic paper display 411ε and the sixth electronic paper display 411ζ form a pair, arranged side by side so that their first third ends 411E3C, which extend along the Y-axis, face each other. In this embodiment, a configuration with one pair of fifth electronic paper displays 411ε and sixth electronic paper displays 411ζ is illustrated, but two or more pairs of fifth electronic paper displays 411ε and sixth electronic paper displays 411ζ may be provided. The pair of fifth electronic paper displays 411ε and sixth electronic paper displays 411ζ are sandwiched between the first electronic paper display 411α and the third electronic paper display 411γ in the Y-axis direction, and also sandwiched between the second electronic paper display 411β and the fourth electronic paper display 411δ in the Y-axis direction. The first electronic paper display 411α has its other third end 411E3B, which extends along the X-axis, positioned to face a second third end 411E3D, which extends along the X-axis, in the fifth electronic paper display 411ε, which is included in a pair of fifth and sixth electronic paper displays 411ε and 411ζ. The third electronic paper display 411γ has its other third end 411E3B, which extends along the X-axis, positioned to face a third third end 411E3E, which extends along the X-axis, in the fifth electronic paper display 411ε, which is included in a pair of fifth and sixth electronic paper displays 411ε and 411ζ.The second electronic paper display 411β has its other third end 411E3B, which extends along the X-axis, positioned to face a second third end 411E3D, which extends along the X-axis, in the sixth electronic paper display 411ζ, which is included in a pair of fifth electronic paper displays 411ε and sixth electronic paper displays 411ζ. The fourth electronic paper display 411δ has its other third end 411E3B, which extends along the X-axis, positioned to face a third third end 411E3E, which extends along the X-axis, in the sixth electronic paper display 411ζ, which is included in a pair of fifth electronic paper displays 411ε and sixth electronic paper displays 411ζ.

[0098] As shown in Figures 27 and 28, the specular reflective material 445 includes those positioned to the sides of the second ends 411E2 of the first electronic paper display 411α and the second electronic paper display 411β, and those positioned to the sides of the second ends 411E2 of the third electronic paper display 411γ and the fourth electronic paper display 411δ. Of these, the specular reflective material 445 positioned to the sides of the second ends 411E2 of the first electronic paper display 411α and the second electronic paper display 411β has a length dimension that spans both the first electronic paper display 411α and the second electronic paper display 411β. The specular reflectors 445, positioned to the sides of the second ends 411E2 of the third electronic paper display 411γ and the fourth electronic paper display 411δ, have a length dimension that spans both the third electronic paper display 411γ and the fourth electronic paper display 411δ.

[0099] According to this embodiment, by displaying an image on each display surface 411A of the first electronic paper display 411α, second electronic paper display 411β, third electronic paper display 411γ, fourth electronic paper display 411δ, fifth electronic paper display 411ε, and sixth electronic paper display 411ζ, which are arranged so that their respective third ends 411E3 are aligned, it is possible to achieve a screen size approximately three times larger than that of Embodiment 3 (approximately 1.5 times larger than that of Embodiment 4). Specifically, the display area AA has dimensions of approximately 1184 mm on one side and approximately 1254 mm on the other side. Furthermore, since a specular reflector 445 is provided on the outside of each of the second ends 411E2 of the first electronic paper display 411α, the second electronic paper display 411β, the third electronic paper display 411γ, and the fourth electronic paper display 411δ, the efficiency of light utilization can be improved.

[0100] As described above, according to this embodiment, the electronic paper display 411 includes a first electronic paper display (first display panel) 411α, a second electronic paper display (second display panel) 411β, a third electronic paper display (third display panel) 411γ, a fourth electronic paper display (fourth display panel) 411δ, a fifth electronic paper display (fifth display panel) 411ε, and a sixth electronic paper display (sixth display panel) 411ζ, and the first electronic paper display 411α, the second electronic paper display 411β, the third electronic paper display The display 411γ and the fourth electronic paper display 411δ are rectangular in shape and include two third ends 411E3, one first end 411E1, and one second end 411E2 at their outer periphery, where LEDs 440, concave mirrors 443, and specular reflectors 445 are not provided. The fifth electronic paper display 411ε and the sixth electronic paper display 411ζ are rectangular in shape and include three third ends 411E3, where LEDs 440, concave mirrors 443, and specular reflectors 445 are not provided, and one first end 411E1 at their outer periphery. The 411α and the second electronic paper display 411β are arranged so that one of their third ends 411E3A is adjacent to the other, the third electronic paper display 411γ and the fourth electronic paper display 411δ are arranged so that one of their third ends 411E3A is adjacent to the other, and the fifth electronic paper display 411ε and the sixth electronic paper display 411ζ are arranged so that their first third ends 411E3C are adjacent to each other, forming a pair, and there are n such pairs (n: a natural number), and the n pairs of the fifth electronic paper display 411ε and the sixth electronic paper display 411ζ are the first It is positioned between the electronic paper display 411α and the third electronic paper display 411γ, and between the second electronic paper display 411β and the fourth electronic paper display 411δ, and the other third end 411E3B of the first electronic paper display 411α is positioned to be aligned with the second third end 411E3D of the fifth electronic paper display 411ε, which is included in the n sets of fifth electronic paper displays 411ε and sixth electronic paper displays 411ζ, and the other third end 411E3B of the third electronic paper display 411γ is positioned to be aligned with the second third end 411E3D of the fifth electronic paper display 411ε,The second electronic paper display 411β is positioned so as to be aligned with the third third end 411E3E of the fifth electronic paper display 411ε, which is included in the n-set fifth electronic paper display 411ε and sixth electronic paper display 411ζ, and the other third end 411E3B of the second electronic paper display 411β is positioned so as to be aligned with the second third end 411E3D of the sixth electronic paper display 411ζ, which is included in the n-set fifth electronic paper display 411ε and sixth electronic paper display 411ζ, and the fourth electronic paper display 41 1δ is positioned such that the other third end 411E3B is aligned with the third third end 411E3E of the sixth electronic paper display 411ζ, which is included in the n sets of fifth electronic paper displays 411ε and sixth electronic paper displays 411ζ, and the specular reflector 445 is positioned laterally to each of the two second ends provided in the first electronic paper display 411α, the second electronic paper display 411β, the third electronic paper display 411γ, and the fourth electronic paper display 411δ. By displaying images on the display surfaces 411A of the first electronic paper displays 411α, second electronic paper displays 411β, third electronic paper displays 411γ, fourth electronic paper displays 411δ, fifth electronic paper displays 411ε, and sixth electronic paper displays 411ζ, which are arranged so that their respective third ends 411E3 are aligned, a larger screen size can be achieved. Furthermore, since a specular reflector 445 is provided on the outside of each of the second ends 411E2 of the first electronic paper displays 411α, second electronic paper displays 411β, third electronic paper displays 411γ, and fourth electronic paper displays 411δ, the efficiency of light utilization can be improved.

[0101] <Other Embodiments> The technology disclosed herein is not limited to the embodiments described above in the description and drawings, but also includes, for example, the following embodiments.

[0102] (1) In the configurations described in Embodiments 1 and 2, it is also possible to arrange multiple electronic paper displays 11, 111 side by side. The arrangement of the multiple electronic paper displays 11, 111 can be as shown in Embodiments 3 to 5, but other arrangements (for example, (2) and (3) below) are also acceptable. The number of electronic paper displays 11, 111 installed may be five or seven or more.

[0103] (2) In the configuration described in Embodiment 3, it is also possible to arrange the two electronic paper displays 211 side by side along the X-axis.

[0104] (3) In the configuration described in Embodiment 3, it is also possible to arrange three or more electronic paper displays 211 in a row along the Y-axis or X-axis.

[0105] (4) In the configuration described in Embodiment 3, the louvers 46 may have a width dimension that is about the same as the thickness of the gap S between the electronic paper display 211 and the light-transmitting panel 213 (the opening width of the opening 244D). In that case, the louvers 46 can also be fitted into the opening 244D of the housing 244.

[0106] (5) In the configurations described in Embodiments 3 to 5, the specular reflectors 245, 345, and 445 may be omitted.

[0107] (6) In the configurations described in Embodiments 4 and 5, the louvers 346 and 446 may be omitted.

[0108] (7) In the configuration described in Embodiment 5, four or more electronic paper displays 411 may be arranged along the Y-axis. That is, two or more sets of the fifth electronic paper display 411ε and the sixth electronic paper display 411ζ may be provided ("n" may be 2 or more). In that case, the number of electronic paper displays 411 installed will be an even number of 8 or more.

[0109] (8) The concave mirrors 43, 143, 243, 343, and 444 may have reflective surfaces 43A, 143A, and 243A of a shape other than a parabolic surface.

[0110] (9) The front light devices 12, 112, 212, 312, 412 may be configured such that the ends of the outer periphery of the electronic paper displays 11, 111, 211, 311, 411 that extend along the X-axis direction (the direction of the long side of the electronic paper displays 11, 111, 211, 311, 411) become the first ends 11E1, 111E1, 211E1, 311E1, 411E1. In other words, the housings 44, 144, 244, 344, 444 that house the LEDs 40, 140, 240, 340, 440, LED substrates 41, 241, 341, 441, reflective sheets 42, 142, 242, 342, 442, and concave mirrors 43, 143, 243, 343, 443 may be positioned laterally to the end of the outer periphery of the electronic paper display 11, 111, 211, 311, 411 that extends along the X-axis.

[0111] (10) The front light devices 12,112,212,312,412 may be configured such that the electronic paper displays 11,111,211,311,411 have multiple first ends 11E1,111E1,211E1,311E1,411E1. In other words, the housings 44,144,244,344,444 that house the LEDs 40,140,240,340,440, LED substrates 41,241,341,441, reflective sheets 42,142,242,342,442, and concave mirrors 43,143,243,343,443 may be arranged in multiple locations so as to be positioned laterally to each of the multiple ends included in the outer peripheral end of the electronic paper displays 11,111,211,311,411.

[0112] (11) Reflective sheets 42, 142, 242, 342, 442 may be omitted from the front light devices 12, 112, 212, 312, 412.

[0113] (12) The light-transmitting panels 13, 113, 213, 313, and 413 may be omitted from the display device 10.

[0114] (13) It is also possible to add a light guide plate to guide light into the gap S between the electronic paper displays 11,111,211,311,411 and the light-transmitting panels 13,113,213,313,413. In other words, the gap S is not synonymous with an air layer, and an optical component such as a light guide plate may be placed therein.

[0115] (14) The electronic paper displays 11, 111, 211, 311, and 411 do not need to be equipped with a color filter 32. In that case, the display surfaces 11A, 111A, 211A, 311A, and 411A will display either black and white or grayscale.

[0116] (15) In (14) above, the electronic paper displays 11, 111, 211, 311, and 411 can also display color using methods other than the color filter 32. For example, by including multiple types of charged particles exhibiting different colors in the microcapsules 30, it is possible to display a color image.

[0117] (16) The electronic paper layer 27 provided in the electronic paper displays 11,111,211,311,411 may be an electrophoretic method other than the microcapsule type (for example, a microcup type, an in-plane method, etc.).

[0118] (17) The planar shape of the electronic paper display 11,111,211,311,411 may be a vertically elongated rectangle, square, trapezoid, rhombus, polygon with pentagons or more sides, circle, semicircle, oval, ellipse, etc.

[0119] (18) The display panel 10 may be a reflective liquid crystal panel or a transflective liquid crystal panel, in addition to the electronic paper displays 11, 111, 211, 311, and 411. [Explanation of Symbols]

[0120] 10...Display device, 11,111,211,311,411...Electronic paper display (irradiated object, display panel), 11A,111A,211A,311A,411A...Display surface (main illuminated surface), 11E1,111E1,211E1,311E1,311E1...First end, 12,112,212,312,412...Front light device (lighting device), 13,113,213,313,41 3…Translucent panel, 13A…Opposite surface, 40, 140, 240, 340, 440…LED (light source), 40A, 240A…Light-emitting surface, 42, 142, 242, 342, 442…Reflective sheet (reflective material), 43, 143, 243, 343, 443…Concave mirror, 43A, 143A, 243A…Reflective surface, 45, 245, 345, 445…Mirror reflective material, 46, 346, 446…Louver, 46C…Light-shielding part 46D…Translucent section, 111E2,211E2,311E2,411E2…Second end, 211α,311α,411α…First electronic paper display (first display panel), 211β,311β,411β…Second electronic paper display (second display panel), 211E3,311E3…Third end, 311γ,411γ…Third electronic paper display (third display panel), 311δ,411δ …Fourth electronic paper display (fourth display panel), 311E3A, 411E3A…one third end, 311E3B, 411E3B…the other third end, 411ε…fifth electronic paper display (fifth display panel), 411ζ…sixth electronic paper display (sixth display panel), 411E3C…first third end, 411E3D…second third end, 411E3E…third third end, S…gap

Claims

1. A light source having a light-emitting surface that emits light for irradiating the main surface of the object to be irradiated, The system comprises a concave mirror positioned laterally to the object to be irradiated and facing the light-emitting surface of the light source, The concave mirror is an illumination device having a reflective surface configured to cause reflected light to travel along the main surface to be illuminated.

2. The lighting device according to claim 1, comprising a reflective material that extends from the light source to the concave mirror and reflects light.

3. The louvers are positioned laterally to the object to be irradiated and facing the reflective surface, The lighting device according to claim 1 or claim 2, wherein the louver has two light-shielding portions arranged at intervals in the direction normal to the main surface to be illuminated, and a light-transmitting portion arranged between the two light-shielding portions.

4. A lighting device according to claim 1 or claim 2, The system includes a display panel that uses light from the aforementioned light source to display information, The display panel is the irradiated object and is a display device having a display surface on which an image is displayed as the irradiated main surface.

5. The light source and the concave mirror are positioned laterally to the first end included in the outer peripheral edge of the display panel. The display device according to claim 4, wherein the light source is positioned closer to the first end than the concave mirror.

6. The display device according to claim 5, wherein the display panel comprises a specular reflecting material that specularly reflects light, which is positioned laterally to the second end of the outer peripheral edge of the display panel where the light source and the concave mirror are not located.

7. The display panel has a rectangular shape, and its outer peripheral edge includes one first end and three second ends. The display device according to claim 6, wherein the specular reflective material is arranged laterally with respect to each of the three second ends.

8. The display panel is rectangular in shape and includes, at its outer peripheral edge, one third end where the light source, the concave mirror, and the specular reflector are not positioned, one first end, and two second ends. The display panel includes a first display panel and a second display panel. The first display panel and the second display panel are arranged so that their third ends are aligned with each other. The display device according to claim 6, wherein the specular reflective material is arranged laterally to each of the two second ends provided on the first display panel and the second display panel.

9. The display panel is rectangular in shape and includes, at its outer peripheral edge, two third ends where the light source, the concave mirror, and the specular reflector are not positioned, one first end, and one second end. The display panel includes a first display panel, a second display panel, a third display panel, and a fourth display panel. The first display panel and the second display panel are arranged such that one of their third ends aligns with the other. The third display panel and the fourth display panel are arranged such that one of their third ends aligns with the other. The first display panel and the third display panel are arranged such that their other third ends are aligned. The second display panel and the fourth display panel are arranged such that their other third ends are aligned. The display device according to claim 6, wherein the specular reflective material is arranged laterally to each of the second ends provided on the first display panel, the second display panel, the third display panel, and the fourth display panel.

10. The display panel includes a first display panel, a second display panel, a third display panel, a fourth display panel, a fifth display panel, and a sixth display panel. The first display panel, the second display panel, the third display panel, and the fourth display panel are rectangular in shape and include two third ends, one first end, and one second end at their outer peripheral ends, where the light source, the concave mirror, and the specular reflector are not positioned. The fifth and sixth display panels are rectangular in shape and include three third ends and one first end at their outer periphery, where the light source, the concave mirror, and the specular reflector are not positioned. The first display panel and the second display panel are arranged such that one of their third ends aligns with the other. The third display panel and the fourth display panel are arranged such that one of their third ends aligns with the other. The fifth display panel and the sixth display panel are arranged so that their first third ends are aligned, and n such sets are provided (n: a natural number). The n sets of the fifth and sixth display panels are sandwiched between the first and third display panels, and between the second and fourth display panels, The first display panel is arranged such that the other third end is aligned with the second third end of the fifth display panel included in the n sets of fifth and sixth display panels. The third display panel is arranged such that the other third end of the fifth display panel is aligned with the third third end of the fifth display panel included in the n sets of fifth and sixth display panels. The second display panel is arranged such that the other third end is aligned with the second third end of the sixth display panel, which is included in the n sets of fifth and sixth display panels. The fourth display panel is arranged such that the other third end is aligned with the third third end of the sixth display panel, which is included in the n sets of fifth and sixth display panels. The display device according to claim 6, wherein the specular reflective material is arranged laterally to each of the second ends provided on the first display panel, the second display panel, the third display panel, and the fourth display panel.

11. A light-transmitting panel is provided, having an opposing surface facing the display surface, with a gap between the display surface and the opposing surface. The display device according to claim 4, wherein the concave mirror is arranged such that its reflective surface faces the gap.

12. The display device according to claim 4, wherein the display panel is an electronic paper display.

Images