Light guide optical component, lighting device using the light guide optical component, and projection display device using the lighting device

Abstract

To provide a light guide optical component, a lighting device using the light guide optical component, and a projection image display device using the lighting device in which more light than conventional art is acquired from an LED light source, and which can form a uniform illuminance distribution and a light flux with small divergence angle on a light emission face.SOLUTION: In a light guide optical component, a bottom face of a tapered part of a first truncated pyramid part having an inclined angle in a horizontal direction and a vertical direction is a light emission face, and a top face is a rectangle CPC with an incident face as a bottom face or a second truncated pyramid or an elliptical truncated pyramid, or a circle CPC is continuously formed as a light incident part. At any position on these incident side faces, an inclined angle of a tangent plant is larger than a taper angle of a tapered part at a corresponding position. A ratio of a length of the tapered part and a length D of a diagonal line of an emission face of the length of the incident part is in a range of: 1.5-5 when the incident part is rectangle CPC; 2.4-5 when the second truncated pyramid; 2-5 when the elliptical truncated pyramid; and 2.4-5 when a circle CPC, which allows a uniform emission light with a small divergence angle.SELECTED DRAWING: Figure 17

Description

[Technical Field]

[0001] The present invention relates to a light-guiding optical component for the light flux from an LED light source, which enables effective use of the light flux from the light source to illuminate display elements (also called light valves) such as transmissive liquid crystal display elements, reflective liquid crystal display elements, and DMD (Digital Micromirror Device) display elements uniformly and with the same brightness within the plane, an illumination device using the light-guiding optical component, and a projection display device (also called a projector) using the illumination device. [Background technology]

[0002] Data projectors are widely used as image projection devices for projecting images displayed on personal computer screens and video footage onto a screen. In recent years, they have also become popular for use in applications other than traditional presentations, such as "smart projectors" that can access websites and project videos using the projector alone, and palm-sized "ultra-compact projectors."

[0003] Projectors can use ultra-high pressure mercury lamps, LEDs, lasers, etc. as light sources, but in recent years LEDs have become more popular as they have a long lifespan and cause almost no temperature rise.With the exception of types that use a scanning laser to draw directly on the screen, most projectors illuminate a light valve, which is the display element, and project the image reproduced by the display element's "on" and "off" control of the light onto the screen.

[0004] Typical color projectors that use display elements use a system in which images are reproduced on separate display elements corresponding to the three RGB colors and light carrying the image information is superimposed, or a system in which a single display element is illuminated with the three RGB colors in a time-division manner, projecting a three-color image onto a screen in a time-division manner.

[0005] In order to project a bright, uniform image onto the screen, it is important to capture as much light as possible from the light source and to illuminate the display element uniformly. Various methods have been devised to illuminate the display element with uniform illuminance using light emitted from the light source.

[0006] Methods for uniformly illuminating a display element mainly involve the use of a fly-eye lens and a light tunnel.

[0007] In an optical system using a fly-eye lens, two fly-eye lenses and a condenser lens are combined to project the real images of each cell of the first fly-eye lens so that they overlap on the display element, and the light distribution illuminance of each cell is averaged, thereby achieving a uniform light distribution.

[0008] In a light distribution homogenizing optical system using a light tunnel, incident light is repeatedly reflected inside the light tunnel, homogenizing the intensity at the exit surface, and a real image of this homogenous light distribution is projected onto a display element, illuminating the display element with uniform intensity.

[0009] If the angle between the light illuminating these display elements and the optical axis becomes large, disadvantages arise such as a decrease in light utilization efficiency and difficulty in compacting the optical system for projecting the image of the display element, etc. Therefore, in optical systems that illuminate these display elements with uniform illuminance, many are devised to reduce the angle between the light illuminating the display element and the optical axis.

[0010] A method using a rod lens has been proposed as a method for uniformly illuminating a display element (Patent Document 1). According to this method, the rod lens not only guides the light emitted from the light source to a polarizing plate in a subsequent process, but also causes the light to be repeatedly reflected on the inner surface of the rod lens as it passes through, and the light reflected at various angles is superimposed on the exit surface of the rod lens, thereby homogenizing the illuminance distribution of the light.

[0011] In order to be able to efficiently utilize the emitted light and obtain bright projected images even when using a light source with a large divergence angle of the emitted light, such as an LED light source, a projection type image display device has been proposed in which the illumination optical system has a light pipe array consisting of tapered light pipes with a diverging shape that reduces the divergence angle of the light rays from each light source unit (Patent Document 2). [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-329978 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-235338 [Patent Document 3] Japanese Patent Application Publication No. 2-1818 [Patent Document 4] Japanese Patent Application Publication No. 7-98416 [Patent Document 5] Japanese Patent Application Publication No. 11-142780 [Patent Document 6] Japanese Patent Application Laid-Open No. 2004-252112 [Patent Document 7] Japanese Patent Application Laid-Open No. 2009-31717 [Patent Document 8] Japanese Patent Application Laid-Open No. 2011-133899 [Patent Document 9] Special Publication No. 2009-544063 [Patent Document 10] Japanese Patent Application Laid-Open No. 2007-199163 [Patent Document 11] Japanese Patent Application Laid-Open No. 2007-288169 Summary of the Invention [Problem to be solved by the invention]

[0013] In the solid light tunnel 101 of a rectangular prism shape shown in FIG. 1, when a light ray incident from the entrance surface 102 is guided inside while being totally reflected by the side surface 104, the angle that the light ray makes with the optical axis does not change, and therefore the angle that the light ray emitted from the exit surface 103 makes with the optical axis is the same as the angle that the incident light makes with the optical axis.

[0014] In contrast, when a ray of light is incident on the entrance surface 202 of a solid tapered light tunnel 201, which has a tapered truncated quadrangular pyramid shape as shown in Figure 2, the angle that the ray makes with the optical axis decreases each time the ray is reflected by the inclined side surface 204 of the light tunnel as it travels toward the exit surface 203.

[0015] Patent Document 3 discloses a light guide device having a substantially quadrangular pyramid shape with parabolic (non-imaging curved) side surfaces, in order to obtain a substantially parallel light beam at the exit surface of the light guide device.

[0016] Patent Document 4 also uses a light guide that diverges toward the end for the same reason, and discloses, as an example, a light guide that has a tapered portion and a parallel portion, which is a combination of a truncated cone and a cylinder, or a combination of a truncated cone and a hexagonal prism.

[0017] Patent document 5 discloses a partial tapered rod that combines a square prism and a truncated pyramid, or a square prism and a truncated cone, and claims that by controlling the taper angle of this partial tapered rod, the parallelism of the converging light beam from the light source lamp can be set to a desired value, the divergence angle of the illumination light beam can be reduced, and the relay optical system that forms an image on the illuminated surface can be made compact.

[0018] However, if the length of the tapered light tunnel 201 is not sufficient relative to the size of the exit surface 203, light rays that enter the entrance surface 202 at a small angle will not be able to undergo a sufficient number of reflections, and light rays that enter the entrance surface 202 at a large angle will be reflected relatively many times, but will still form a large angle with the optical axis when they reach the exit surface 203.

[0019] To achieve a uniform light distribution at the exit surface 203 by passing light through a tapered light tunnel, a certain number of reflections are required on the side surfaces 204 of the tapered light tunnel, so it is generally necessary to aim to increase the number of reflections by guiding convergent or divergent light with a high NA (NA is numerical aperture) to the entrance surface 202. Furthermore, when introducing convergent or divergent light with a low NA, which contains many rays that make a small angle with the optical axis, it is necessary to use a long light tunnel to increase the number of reflections.

[0020] On the other hand, in order to miniaturize the optical system, it is desirable to have a short tapered light tunnel, but in order to make the light distribution at the exit surface 203 uniform using a short light tunnel, it is necessary to guide converging or diverging light with a high NA, which tends to increase the divergence angle of the light emitted from the exit surface 203.

[0021] The larger the angle that the side surface 204 of the tapered light tunnel makes with the optical axis, the smaller the angle that the light rays reflected by the side surface 204 of the tapered light tunnel make with the optical axis, and the smaller the divergence angle of the light emitted from the exit surface 203. However, since a larger number of reflections is advantageous for achieving a uniform light intensity distribution at the exit surface 203, a large angle that the side surface 204 of the tapered light tunnel makes with the optical axis is likely to result in a non-uniform light distribution at the exit surface 203. In other words, for a given light tunnel length, it is thought that there is an appropriate range for the angle (tilt angle) that the side surface 204 of the tapered light tunnel makes with the optical axis.

[0022] Therefore, in a tapered light tunnel that is short in length relative to the size of the exit surface 203, it is extremely difficult to achieve both a uniform light distribution at the exit surface 203 and a small divergence angle of the exit light.

[0023] Patent Document 6 relates to an image projection device and an illumination device used therein, in which a lamp is placed at the first focal point of an elliptical reflecting mirror and the center of the entrance surface of a light tunnel is placed at the second focal point, and this light tunnel consists of a tapered section whose cross-sectional shape continuously decreases from the entrance surface to the exit surface and a parallel section whose cross-sectional shape is constant, and the shape of the exit surface is formed to be similar to the shape of the entrance surface of the light valve. However, according to this invention, although the utilization efficiency of light from the incident light source is increased, because the light tunnel consists of a parallel section, the spread of the light beam at the exit surface is not improved.

[0024] Patent Document 7 provides an optical system unit having a light guide device capable of emitting a light beam substantially parallel to the optical axis, and a projector equipped with the optical system unit. The optical system unit includes a light tunnel as a light guide device, which is a light source-side optical system. The light tunnel has four approximately rectangular plates forming top, bottom, left, and right surfaces. The light tunnel is formed into a substantially quadrangular truncated pyramid shape by stacking and fixing the top and bottom plates on the sides of the side plates arranged diagonally opposite each other. As a result, the side plates are formed diagonally so that the area of ​​the exit surface of the light tunnel is larger than the area of ​​the entrance surface, allowing the lateral angle of the light beam to approach that of a light beam parallel to the optical axis. However, as already mentioned, simply forming a light tunnel with diagonally opposed plates does not achieve both light homogeneity and a reduced divergence angle.

[0025] Patent Document 8 relates to a light guide device and a projector, which includes a cylindrical light tunnel with a rectangular parallelepiped outer shape and a hollow interior, and a glass rod, in order to capture a larger amount of light beams emitted from a light source device and to output light beams that form a large angle with the optical axis as light beams at a gentler angle, the light tunnel having one end as an entrance and the other end as an exit end, with a reflective surface on its inner surface, making the internal space a light guide path, the glass rod having a tapered portion that diverges from the entrance end toward the exit end, and the tapered portion is disposed within the light guide path of the light tunnel, making the bottom surface of the glass rod a light exit. However, according to this invention, since the light guide device is composed of a hollow cylindrical light tunnel with a reflective surface on its inner surface and a glass rod with a tapered portion that diverges, the light guide device inevitably becomes complicated and expensive.

[0026] Patent Document 9 discloses a light collector used in the field of projection, which collects light from different colored surface-emitting light sources (e.g., LEDs) using an input light pipe. The specification discloses a light pipe with a double tapered shape in one surface direction as an example of the light collector.

[0027] Patent Document 10 aims to efficiently uniformize illumination unevenness at the exit surface without extending the overall length when guiding diffused light to an optical element having an optical surface parallel to the optical axis. It is a light-guiding element that guides diffused light emitted from a light source to an optical element having an optical surface parallel to the optical axis, and is provided with a plurality of tapered rod sections arranged adjacent to each other along a central axis direction passing through approximately the center of the incident end and the exit end between an incident end arranged on the light source side and an exit end arranged on the optical element side, each tapered rod section having a shape that gradually widens at a constant taper angle from the incident end toward the exit end side, and the taper angle of each tapered rod section is set to be smaller than the taper angle of the tapered rod section adjacent to the incident end side.

[0028] Patent Document 11 discloses an optical element that has excellent light utilization efficiency and can be made smaller, thinner, and lighter with a simple configuration, and realizes a lighting device and an image display device using the same. The optical element comprises a light source composed of a light-emitting device that can emit multiple colored lights and has a set of multiple colors that can selectively emit light from a desired element, and a rod lens array in which rod lenses are arranged two-dimensionally, the first surface being made of a material transparent to the light from the light source and having an area equal to or greater than the area of ​​the light source and a second surface opposing the first surface, with the two surfaces serving as bases. In this optical element, a light source composed of a light-emitting device that has a set of multiple colors is arranged on the first surface side of each rod lens of the rod lens array, and by homogenizing the illuminance of the light emitted from the light source by each rod lens, it is possible to homogenize the illuminance for each colored light at the second surface of the rod lens array.

[0029] The problem that the present invention aims to solve is to provide a light-guiding optical component that can take in more light from an LED light source than conventional technology, has uniform emitted illuminance, and can irradiate a light valve with a light beam with a small divergence angle, and is more compact than conventional technology; an illumination device that uses the light-guiding optical component; and a projection-type image display device that uses the illumination device. [Means for solving the problem]

[0030] In order to solve the above-mentioned problems of the prior art, the first invention of the present application provides a rectangular CPC having a rectangular entrance surface of height H1 and width W1 (square when H1=W1) and a rectangular exit surface of height H2 and width W2 (H2>H1, W2>W1), a solid tapered portion of length L1 that is a truncated square pyramid that diverges in the direction of light travel at an angle β1 in the height direction and an angle β2 in the width direction with respect to the optical axis, and a rectangular CPC having a height H3 and width W3 (square when H3=W3) as a bottom surface, and a solid entrance portion of length L2 that is a rectangular CPC is formed continuously, The upper and lower side surfaces and the left and right side surfaces are all made of internal reflection type compound paraboloids, the angle β3 that the tangent plane makes with the horizontal plane including the optical axis at any position on the upper and lower side surfaces is larger than the angle β1 mentioned above, the angle β4 that the tangent plane makes with the vertical plane including the optical axis at any position on the left and right side surfaces is larger than the angle β2 mentioned above, and the sum (total length L) of the tapered portion and the length L2 of the rectangular CPC is at least 1.5 times or more the length D of the diagonal of the exit surface of the tapered portion which is a flared truncated quadrangular pyramid having a height H2 and a width W2.

[0031] Here, a rectangular CPC refers to a rectangular truncated pyramid-like shape consisting of a top surface, a bottom surface, and four side surfaces, all of which are internal-reflection compound paraboloids. Light enters the top surface of the solid rectangular CPC entrance portion, reflects off the top, bottom, and left and right side surfaces, travels from the bottom surface to the entrance surface of the tapered portion, which is a flared truncated pyramid, and then travels to the exit surface after repeatedly reflecting off the side surfaces of the tapered portion. The fact that β3 is greater than β1 and β4 is greater than β2 means that the light is reflected at the rectangular CPC entrance portion so that its traveling direction approaches the optical axis before entering the tapered portion, which is a flared truncated pyramid.

[0032] In other words, in such a light-guiding optical component, light incident on the top surface, which is a rectangle or square with a height H3 and a width W3, is reflected by the four sides of the rectangular CPC (the top and bottom sides and the left and right sides), changing direction significantly, and reaches the bottom surface of the rectangular CPC with a height H1 and a width W1, then enters the tapered portion, which is a flared truncated quadrangular pyramid, and is repeatedly reflected by the sides of the tapered portion before reaching the rectangular exit surface with a height H2 and a width W2 and exiting from the exit surface.

[0033] Ray tracing simulations, described later, revealed that when the sum (total length L) of the tapered portion length L1 and the length L2 of the rectangular CPC is at least 1.5 times the diagonal length D of the exit surface of the tapered portion, which is a flared truncated quadrangular pyramid with a height H2 and a width W2, the illuminance distribution of light rays at the exit surface of the tapered portion is stable and uniform, and the divergence angle of light rays diverging from the exit surface is stable and small, i.e., the linearity is increased. Furthermore, the length L2 of the rectangular CPC is in the range of 2.4% to 13.4% of the tapered portion length L1, the β1 is in the range of 1.9° to 5.8°, and the β2 is in the range of 4.1° to 13.8°. The size of the rectangular exit surface, with a height H2 and a width W2, is equal to or at least similar to the size of the display element illuminated by the light-guiding optical component of the present invention.

[0034] FIG. 3 illustrates an example of the configuration of the light-guiding optical component of the first aspect of the present invention. Reference numeral 301 denotes an overall view, which can be described as a light tunnel with a double-tapered structure consisting of an entrance portion that is a rectangular CPC and a tapered portion that is a truncated square pyramid. The upper surface 305 of the truncated square pyramid, which is the tapered portion that flares outward, is formed contiguous with the upper surface 307 of the entrance portion of the rectangular CPC, and the right surface 304 of the truncated square pyramid is formed contiguous with the right surface 308 of the entrance portion of the rectangular CPC. The same applies to the lower and left surfaces. The upper surface 302 of the rectangular CPC is the entrance surface for light from the light source, and the bottom surface 303 of the truncated square pyramid, which is the tapered portion that flares outward, is the exit surface. Note that imaginary surface 306 is the bottom surface of the rectangular CPC and also the entrance surface of the truncated square pyramid.

[0035] Here, the inclination angle β1 (taper angle β1) which is the angle between the horizontal plane including the optical axis and the upper surface 305 or the lower surface of the tapered portion, and the angle β2 (taper angle β2) which is the angle between the vertical plane including the optical axis and the left side surface or the right side surface 304 of the tapered portion are given by: β1=arctan{(H2-H1) / 2L1}, β2=arctan{(W2-W1) / 2L1)} (See Figures 4 and 5). The closer the light is to the optical axis, the more the parallelism of the light reflected by the tapered surface improves in the height direction by approximately 2β1 per reflection on the top and bottom surfaces, and in the width direction by approximately 2β2 per reflection on the left and right surfaces. In the present invention, when the sum of the tapered section length L1 and the incident section length L2, i.e., the total length L, is 1.5 times or more the diagonal length D of the exit surface, it is possible to homogenize the light from the light source and reduce the divergence angle with a shorter length than the conventional tapered light tunnel. However, it was also found that even with the conventional tapered light tunnel, the light from the light source can be homogenized and the divergence angle reduced when the length is 6 times or more the diagonal length D of the exit surface. Therefore, the advantage of the first invention is that it can homogenize the light from the light source and reduce the divergence angle, which was not possible with the conventional tapered light tunnel, even when the total length L is 1.5 to 5 times the diagonal length D of the exit surface.

[0036] In the first aspect of the present invention, the incident section is formed as a rectangular CPC incident section, with the top surface 306 of the truncated quadrangular pyramid serving as the tapered section serving as the base, and the top surface 302 of the incident section serves as the incident surface for light from the light source. As shown in FIG. 6 , light incident at a large angle of incidence on incident surface 302 first strikes side surface 307 of the incident section, where the angle it makes with the optical axis suddenly decreases, and then proceeds to the tapered section. At any position on the top surface 307 of the incident section, the angle β3 that the tangent makes with the optical axis is greater than the taper angle β1 of the tapered section. This relationship also applies to the bottom, left, and right surfaces of the incident section, where the angle that the tangent plane makes with a horizontal or vertical plane containing the optical axis at a certain position is greater than the taper angle of the corresponding tapered section.

[0037] The process in which light incident on the light-guiding optical component of the present invention is repeatedly reflected at the incident section and tapered section before reaching the exit surface is shown in Figure 7. Due to the presence of the incident section made of a rectangular CPC, the light incident on the incident surface 302 of the incident section is homogenized over a shorter length than in light-guiding optical components that are conventional tapered light tunnels made only of a truncated quadrangular pyramid, and reaches the exit surface 303 of the tapered section.

[0038] Next, the second invention of the present application is directed to a rectangular or square incident surface (when H1=W1) having a height H1 and a width W1, a rectangular exit surface (H2>H1, W2>W1) having a height H2 and a width W2, a solid tapered portion having a length L1 which is a first truncated quadrangular pyramid that diverges in the direction of light travel at an angle β1 in the height direction and an angle β2 in the width direction with respect to the optical axis, and a solid incident portion having a length L2 which is a second truncated quadrangular pyramid that has a square or rectangular bottom surface having a height H3 and a width W3, and The light-guiding optical component is characterized in that the four side surfaces of the second truncated quadrangular pyramid are flat trapezoids, and the trapezoids on the top and bottom sides form an angle β5 that is greater than the taper angle β1 at any position with a horizontal plane including the optical axis, and the trapezoids on the left and right sides form an angle β6 that is greater than the taper angle β2 at any position with a vertical plane including the optical axis, and the sum of the length L1 of the tapered portion and the length L2 of the second truncated quadrangular pyramid (total length L) is 2.4 to 5 times the length D of the diagonal of the exit surface of the tapered portion of the first truncated quadrangular pyramid. As will be described in detail later, the length L2 of the second truncated quadrangular pyramid is in the range of 5.8% to 19.6% of the length L1 of the tapered portion, β1 is in the range of 1.1° to 3.3°, and β2 is in the range of 3.3° to 6.4°.

[0039] That is, in the second invention, a second truncated quadrangular pyramid having taper angles β5 and β6 and length L2 is formed continuously from a first truncated quadrangular pyramid having taper angles β1 and β2 and length L1, where β5>β1 and β6>β2 are satisfied, and the relationship between the diagonal length D of the entrance surface and the total length L is 2.4D≦L(=L1+L2)≦5D. The relationship between the entrance portion length L2 and the tapered portion length L1 is 5.8%L1≦L2≦19.6%L1, where the ranges are 1.1°≦β1≦3.3° and 3.3°≦β2≦6.4°.

[0040] In the second aspect of the present invention, the light-guiding optical component has a second truncated quadrangular pyramid serving as an entrance portion formed contiguous with a first truncated quadrangular pyramid serving as a tapered portion, and the four trapezoidal side surfaces of the second truncated quadrangular pyramid are therefore formed contiguous with the four trapezoidal side surfaces of the first truncated quadrangular pyramid. The taper angle β5 formed by the upper and lower two of the four side surfaces of the second truncated quadrangular pyramid with the optical axis is greater than the taper angle β1 formed by the upper and lower two of the four side surfaces of the first truncated quadrangular pyramid with the optical axis, and the taper angle β6 formed by the left and right two of the four side surfaces of the second truncated quadrangular pyramid with the optical axis is greater than the taper angle β2 formed by the left and right two of the four side surfaces of the first truncated quadrangular pyramid with the optical axis.

[0041] In such a light-guiding optical component, light incident on the square or rectangular top surface of the second truncated quadrangular pyramid, which has a height H3 and a width W3, is reflected by the side surfaces of the second truncated quadrangular pyramid, changes direction, reaches the bottom surface of the second truncated quadrangular pyramid, which has a height H1 and a width W1, and then enters the tapered portion of the first truncated quadrangular pyramid, which flares outward, and after repeated reflections on the side surfaces, reaches the rectangular exit surface, which has a height H2 and a width W2, and is emitted from the exit surface.

[0042] That is, in the light-guiding optical component of the second invention, light incident on the top surface of the second truncated quadrangular pyramid is reflected by the top, bottom, left, and right side surfaces of the second truncated quadrangular pyramid at an inclination angle β5 or β6, changing its direction of travel significantly, approaching the optical axis, and traveling toward the exit surface, which is the bottom surface.The light then enters the tapered portion, which is the first truncated quadrangular pyramid, and changes its direction of travel relative to the optical axis in accordance with a taper angle β1 in the height direction and a taper angle β2 in the width direction, traveling closer to the optical axis.

[0043] To reiterate, this is the effect of the angle β5 formed with the optical axis at any position on the top and bottom sides of the four side surfaces of the second truncated quadrangular pyramid being larger than the angle β1, and the angle β6 formed with the optical axis at any position on the left and right sides of the four side surfaces being larger than the angle β2 of the tapered portion. Due to the presence of such a second truncated quadrangular pyramid, light that is incident on the incident surface of the second truncated quadrangular pyramid is homogenized and reaches the exit surface of the first truncated quadrangular pyramid over a shorter length than in a light-guiding optical component that is a conventional tapered light tunnel consisting only of the first truncated quadrangular pyramid.

[0044] In the second invention, the sum of the length L1 of the tapered portion of the first truncated quadrangular pyramid and the length L2 of the second truncated quadrangular pyramid (total length L) needs to be 2.4 to 5 times the diagonal length D of the exit surface. If the sum is less than 2.4 times, it was not possible to find a condition that would improve the homogeneity of the exit light. If the sum is more than 5 times or 6 times, even conventional tapered light tunnels can produce a roughly uniform light beam with a small divergence angle at the exit surface, but tapered light tunnels with a sum of 5 times or less cannot produce a homogeneous light beam with a small divergence angle.

[0045] In the second invention, when the homogenization of the emitted light and the narrowing of the divergence angle were achieved, the length L2 of the incident portion was in the range of 5.8% to 19.6% of the length L1 of the tapered portion, and the inclination angle β1 of the tapered portion, which is the first truncated quadrangular pyramid, was in the range of 1.1° to 3.3°, and the inclination angle β2 of the tapered portion was in the range of 3.3° to 6.4°.

[0046] The first and second inventions are the same in that they have a first truncated quadrangular pyramid, which is a tapered section with taper angles β1 and β2, but differ in the shape of the entrance section formed continuously with the tapered section. In the first invention, the side surface of the rectangular CPC of the entrance section is an internal reflection-type compound paraboloid, as shown in the development diagram in Figure 8, while in the second invention, the side surface is a simple truncated quadrangular pyramid, as shown in the development diagram in Figure 9. In both the first and second inventions, the inclination angle at each position of the entrance section is larger than the taper angle of the corresponding first truncated quadrangular pyramid.

[0047] Next, a third invention of the present application is a light-guiding optical component having a tapered portion of length L1 consisting of a solid truncated square pyramid that diverges in the direction of light travel at a taper angle β7 in the height direction and a taper angle β8 in the width direction relative to the optical axis from a rectangular incident surface of height a1 and width b1 toward a rectangular exit surface of height H2 and width W2 (H2>a1, W2>b1), and further comprising an incident portion of length L2 consisting of an elliptical truncated cone with the rectangle of height a1 and width b1 as its bottom surface and an ellipse with a minor axis a3 and a major axis b3 as its top surface, which is continuous with the tapered portion, and wherein an angle β9 formed between the slope and the optical axis at any position on the elliptical truncated cone is greater than the taper angle β7 and the taper angle β8, and the sum of the length L1 of the tapered portion and the length L2 of the elliptical truncated cone that is the incident portion (total length L) is between two and five times the length D of the diagonal of the exit surface. In such a light-guiding optical component, both the uniformity of light on the exit surface and the narrow angle are achieved on the exit surface.

[0048] When both the uniformity of light at the exit surface and the narrowing of the angle are achieved at the exit surface, the length L2 of the elliptical truncated cone is in the range of 14.2% to 41.6% of the length L1 of the tapered portion, β7 is in the range of 1.2° to 4.2°, and β8 is in the range of 3.1° to 7.3°.

[0049] The difference between the third invention and the first and second inventions is that the incident part is not a square truncated pyramid with a length of L2, but an elliptical truncated cone with a length of L2 (see Figures 10 and 13). Figure 13 shows only the incident part of the elliptical truncated cone.

[0050] The taper angle β7 between the upper and lower surfaces of the tapered portion and the optical axis, and the taper angle β8 between the left and right surfaces and the optical axis are: β7=arctan{(H2-a1) / 2L1}, β8=arctan{(W2-b1) / 2L1)} (See Figures 11 and 12.) With each reflection, the parallelism of light rays reflected by the tapered surface improves by approximately 2β7 in the height direction for light traveling in a direction nearly perpendicular to the optical axis, and by approximately 2β8 in the width direction for light traveling in a direction nearly horizontal to the optical axis.

[0051] 10, the base 303 of the flared truncated quadrangular pyramid is a rectangular light exit surface. In the present invention, a tapered truncated elliptical cone is formed continuously with the top surface of the truncated quadrangular pyramid as its base, and its top surface is elliptical and serves as the light entrance surface 302.

[0052] Light incident at a large angle on the entrance surface 302 of the entrance portion of the elliptical truncated cone is reflected by the inner surface of the elliptical truncated cone (inclination angle β9), which is more inclined than the inclination angles β7 and β8 of the tapered portion, significantly reducing the angle with the optical axis. After entering the tapered portion, the angle with the optical axis decreases by approximately 2β7 or 2β8 with each reflection, and the light reaches the exit surface 303 while improving uniformity. The length L1 of the tapered portion can be made significantly shorter than the length of a conventional tapered light tunnel. Specifically, the sum of the length L1 of the tapered portion and the length L2 of the elliptical truncated cone (total length L) can be between two and five times the diagonal length D of the exit surface.

[0053] 3 and 10, the incident light is a mixture of rays that form a large angle with the optical axis and rays that form a small angle with the optical axis, but by selectively reflecting only the rays with a large incident angle from the side surface of the incident portion, the angle that the reflected rays form with the optical axis is significantly reduced, whereas the rays that form a small angle with the optical axis when they are incident on the incident surface are not reflected from the side surface of the incident portion and are reflected only by the side surface of the tapered portion, so the number of reflections does not decrease. This makes it possible to narrow the angle of the light rays emitted from the exit surface without significantly reducing the uniformity of the light distribution on the exit surface.

[0054] Furthermore, the double taper structure, which combines the shapes of the entrance and tapered sections, allows for greater design freedom compared to the tapered light tunnel with a simple quadrangular pyramid shape shown in Figure 2, and independently adjusting the shapes of the entrance and tapered sections can contribute to homogenizing the light distribution on the exit surface.

[0055] As a result, in the third invention, in a light-guiding optical component whose overall length L is short, that is, between two and five times the length D of the diagonal line of the exit surface, it is possible to achieve both a homogenous light distribution on the exit surface and a narrow divergence angle of the exit light.

[0056] Figure 14 shows that the side of an elliptical truncated cone is a paraboloid that bulges outward, and can also be said to be a modified example of the shape of the entrance part in the third invention. Figure 13 shows a simple elliptical truncated cone, but Figure 14 shows that the slope of the elliptical truncated cone is either a paraboloid or a single curved surface that bulges outward.

[0057] Next, the fourth invention of the present application is a tapered section of length L1 consisting of a truncated quadrangular pyramid that widens from a rectangular entrance surface of height a1 and width b1 toward a rectangular exit surface of height H2 and width W2 at an angle β7 in the height direction and an angle β8 in the width direction with respect to the optical axis, and is connected to this tapered section by an entrance section of length L2 consisting of a rectangular base of height a1 and width b1, a circular top surface of diameter a3, and a circular CPC with internal reflection paraboloidal side surfaces, and the angle β 10 is a light-guiding optical component characterized in that it is larger than β7 and β8, and the sum (total length L) of the length L1 of the tapered portion and the length L2 of the circular CPC that is the incident portion is in the range of 2.4 to 5 times the length D of the diagonal of the exit surface.

[0058] That is, the incident section of the fourth invention is a truncated cone as shown in Figure 15, but the top surface of the incident section is a circle with a diameter a3 rather than an ellipse, the bottom surface of the incident section is a rectangle with a diameter of a1 x b1, and the side surface of the incident section is an internal reflection type compound paraboloid (this shape of the incident section is called a circular CPC).The tapered section, like the third invention, is a truncated quadrangular pyramid that diverges from the rectangular incident surface with a height of a1 and a width of b1 to the rectangular exit surface with a height of H2 and a width of W2, at an angle β7 in the height direction and an angle β8 in the width direction relative to the optical axis.The length of the incident section is L2, and the inclination angle β 10 is larger than the angles β7 and β8 formed by the side surfaces of the tapered portion, which is a flared truncated quadrangular pyramid, and the optical axis.

[0059] In the fourth invention, when the sum (total length L) of the length L1 of the tapered portion and the length L2 of the circular CPC that is the entrance portion is in the range of 2.4 to 5 times the length D of the diagonal of the exit surface, the light uniformity at the exit surface is excellent and the divergence angle is small. In this case, the length L2 of the circular CPC is in the range of 11.3% to 16.7% of the length L1 of the tapered portion, β7 is in the range of 0.5° to 3.5°, and β8 is in the range of 3.0° to 8.1°.

[0060] Light enters the circular entrance surface of the entrance section, is reflected by a parabolic surface, and travels in a direction approaching the optical axis before entering the tapered section. In the tapered section, it reflects once on the top and bottom surfaces, bringing it closer to the optical axis by approximately 2β7° (depending on the angle and direction of incidence), and once on the left and right surfaces, bringing it closer to the optical axis by approximately 2β8° (depending on the angle and direction of incidence), improving uniformity as it travels toward the exit surface and is emitted from the exit surface.

[0061] In the first to fourth inventions of the present application, when the exit surface or the entrance surface is expressed as a rectangle, the four corners do not necessarily have to be right angles in the strict sense, and the corners may be rounded in order to prevent damage due to contact, etc.

[0062] In the first to fourth aspects of the present invention, a condensing lens or a diverging lens can be integrated at the exit surface of the light-guiding optical component as shown in Fig. 16 to create a light-guiding optical component with a condensing or diverging effect. The condensing lens or diverging lens used here typically has one surface that is substantially flat and is integrated with the exit surface, and the other surface is a convex or concave lens with a curvature. This eliminates loss due to divergence of light components with a large divergence angle at the exit surface, allowing light to be irradiated forward from the condensing lens, and when a diverging lens is used, the irradiation area can be increased.

[0063] The fifth invention of the present application is a light-guiding optical component in which a plurality of light-guiding optical components disclosed in the first to fourth inventions of the present application are integrated. The term "multiple" may refer to two, or, for example, an arrangement of M rows and N rows. When referring to "M rows and N rows," at least one of M and N is equal to or greater than two. When configuring a lighting device, the number and configuration of the light-guiding optical components are set equal to the number of LED elements, and the incident surfaces of the incident portions of each light-guiding optical component are arranged facing the LED elements. For example, if the LED elements are arranged in two rows and three rows, the light-guiding optical components are also integrated in two rows and three rows, and the incident surfaces of the incident portions of each light-guiding optical component are arranged in contact with each LED element to form a lighting device. In the case of an M row and N row arrangement, it is possible to consider not arranging light-guiding optical components at the four even corners, or to omit a portion of the center, for ease of handling, to prevent damage due to contact, or for ease of manufacturing. Even in these cases, there is no significant problem with the uniformity of illuminance on the illuminated surface. Also in the fifth aspect of the invention, a condensing lens or a diverging lens may be integrated at the position of the exit surface as shown in FIG.

[0064] 17 and 18 show a 5-column, 5-array light-guiding optical component according to one embodiment of the fifth invention, with Fig. 17 being a perspective view of the entire component as viewed from the light exit surface side, and Fig. 18 being a front view as viewed from the light entrance surface side. In this embodiment, a condenser lens is integrated with the exit surface of each light-guiding optical component. In this embodiment, the 5-column, 5-array configuration has an exit surface that is similar in size to the shape of the light valve, which is the display element.

[0065] The sixth invention of the present application is an illumination device in which an LED element is arranged in contact with the incident surface of the incident part of the light-guiding optical component described in the first to fifth inventions of the present application. For example, this is an illumination device in which an LED element is arranged in contact with the position of incident surface 302 in Fig. 3 or the position of incident surface 302 in Fig. 10. Whichever light-guiding optical component is used, an illumination device with a uniform illuminance distribution on the exit surface can be obtained.

[0066] The seventh invention of the present application is a projection display device in which a light beam from the exit surface of the lighting device according to the sixth invention is focused and irradiated onto a light valve, which is a display element, by a focusing lens system, and the image generated by the display element is enlarged by a magnifying projection optical system and projected onto a screen.

[0067] An example of the configuration of a projection display device is shown in Figure 19. Examples of light valves for projection display devices include transmissive liquid crystal display panels, reflective liquid crystal display panels, and DMDs (digital micromirror devices), but according to the present invention, parallel light with uniform illuminance can be obtained, so it is particularly effective for DMD display elements that are arranged at a distance from the light source and light-guiding optical components.

[0068] Since it is assumed that the real image on the exit surface 303 will be projected onto a display element such as a liquid crystal display element or DMD used in a projector, thereby illuminating with a uniform intensity, it is desirable that the width-to-height ratio of the exit surface 303 be similar to that of the display element. The width W to height H ratio of these display elements is usually 16:9 or 4:3. [Effects of the Invention]

[0069] According to the light-guiding optical component of the present invention, the parameters of the incident section and the tapered section are controlled separately to make the inclination angle at each side of the incident section larger than the taper angle of the tapered section, while maintaining a total length shorter than that of conventional tapered light tunnels. This allows light from a light source to reach the exit surface of the light-guiding optical component as homogeneous light with a small divergence angle, even in a short length that could not be achieved in conventional components. Furthermore, when the ratio of the sum of the tapered section length L1 and the incident section length L2 (total length L) to the diagonal length D of the exit surface is set to 1.5 to 5 when the incident section is a rectangular CPC, 2.4 to 5 when the incident section is a second quadrangular truncated pyramid, 2 to 5 when the incident section is an elliptical truncated cone, or 2.4 to 5 when the incident section is a circular CPC, the exit light can be homogeneous and have a small divergence angle. Furthermore, by arranging and integrating multiple light-guiding optical components, a light-guiding optical component with a large area can be produced.

[0070] The lighting device using the light-guiding optical component and LED light-emitting element of the present invention can provide a lighting device with a uniform illuminance distribution and a small divergence angle. Furthermore, the lighting device can emit light over a wide area by integrating a plurality of light-guiding optical components and LED light-emitting elements.

[0071] In a projection display element using the illumination device of the present invention, the light valve is illuminated with illumination having a very uniform illuminance and a narrow divergence angle, making it possible to project an image with an excellent illuminance distribution onto a screen.The illumination device of the present invention can irradiate parallel light with a uniform illuminance distribution and a small divergence angle, making it suitable for use in a projection display device using a DMD with a wide gap between the illumination device and the light valve. [Brief explanation of the drawings]

[0072] [Figure 1] FIG. 10 is a diagram showing the reflection of light in a rectangular prism-shaped light tunnel. [Figure 2] FIG. 10 is a diagram showing the reflection of light in a tapered light tunnel with a flared truncated square pyramid shape. [Figure 3] 1 is a perspective view showing an example of the configuration of a light-guiding optical component according to a first aspect of the present invention. [Figure 4] 1 is a side view of an example of the configuration of a light-guiding optical component according to a first aspect of the present invention. [Figure 5] 1 is a plan view of an example of the configuration of a light-guiding optical component according to a first aspect of the present invention. [Figure 6] FIG. 2 is a diagram showing the path of light incident on an incident portion of the first invention of the present application. [Figure 7] 1 is a diagram showing how light incident on an incident surface exits from an exit surface in the first invention of the present application. FIG. [Figure 8] 1 is a diagram showing a rectangular CPC that is an incident portion of a light-guiding optical component according to a first aspect of the present invention. [Figure 9] FIG. 2 is a diagram showing a truncated quadrangular pyramid that is an entrance portion of a light-guiding optical component according to a second aspect of the present invention. [Figure 10] FIG. 10 is a perspective view showing an example of the configuration of a light-guiding optical component according to a third aspect of the present invention. [Figure 11] FIG. 10 is a side view of an example of the configuration of a light-guiding optical component according to a third invention of the present application. [Figure 12] FIG. 10 is a plan view of an example of the configuration of a light-guiding optical component according to a third aspect of the present invention. [Figure 13] FIG. 10 is a diagram showing an elliptical truncated cone that is an entrance portion of an optical guide component according to a third aspect of the present invention. [Figure 14] 10 is a diagram showing another aspect of an elliptical truncated cone, which is an example of the incident portion of the optical guide component of the third invention of the present application. FIG. [Figure 15] FIG. 10 is a diagram showing a circular CPC, which is an example of an incident portion of an optical guide component according to a fourth aspect of the present invention. [Figure 16] FIG. 2 is a diagram showing an example in which a condenser lens is integrated with the exit surface of a light-guiding optical component, which is an example of the first invention of the present application. [Figure 17] 1 is a perspective view showing an example of a light-guiding optical component in which a plurality of light-guiding optical components according to the first invention of the present application are arranged and integrated. [Figure 18] 1 is a plan view showing an example of a light-guiding optical component in which a plurality of light-guiding optical components according to a first invention of the present application are arranged and integrated. [Figure 19] FIG. 10 is a diagram showing an example of the configuration of a projection display device according to a seventh aspect of the present invention, which uses an example of an illumination device according to a sixth aspect of the present invention. [Figure 20] FIG. 10 is a diagram showing the angle β3 formed by a tangent plane at any position on the top or bottom surface of a rectangular CPC and a horizontal plane including the optical axis in the first invention of the present application. [Figure 21] 4 is a diagram showing an example of the results of a ray tracing simulation of a light beam incident on the light-guiding optical component of the first invention. FIG. [Figure 22] 3 is a diagram showing an example of an illuminance distribution in the X direction (width direction) on the exit surface of a light beam that has entered the light-guiding optical component of the first invention. FIG. [Figure 23] FIG. 10 is a diagram showing an example of the illuminance distribution in the Y direction (height direction) on the exit surface of a light beam incident on the first light-guiding optical component of the present invention. [Figure 24]3 is a diagram showing an example of the distribution of divergence angles in the X direction (width direction) and the Y direction (height direction) on the exit surface of a light beam that has entered the light-guiding optical component of the first invention. FIG. [Figure 25] 6 is a diagram showing another example of the results of a ray tracing simulation of light rays incident on the light-guiding optical component of the first invention. FIG. [Figure 26] 10 is a diagram showing another example of the illuminance distribution in the X direction (width direction) on the exit surface of the light beam that has entered the light-guiding optical component of the first invention. FIG. [Figure 27] 10 is a diagram showing another example of the illuminance distribution in the Y direction (height direction) on the exit surface of a light beam that has entered the light-guiding optical component of the first invention. FIG. [Figure 28] 6 is a diagram showing another example of the distribution of divergence angles in the X and Y directions on the exit surface of a light beam that has entered the light-guiding optical component of the first invention. FIG. [Figure 29] 10 is an example of a result of a ray tracing simulation of light rays incident on a tapered light tunnel, which is a comparative example. [Figure 30] 10 is an example showing an illuminance distribution in the X direction on the exit surface of a light ray that has entered a tapered light tunnel that is a comparative example. [Figure 31] 10 is an example showing the Y-direction illuminance distribution on the exit surface of a light beam incident on a tapered light tunnel that is a comparative example. [Figure 32] 10 is a diagram showing an example of the results of a ray tracing simulation of a light beam incident on the light-guiding optical component according to the second invention. FIG. [Figure 33] 10 is a diagram showing an example of an illuminance distribution in the X direction (width direction) on the exit surface of a light beam that has entered a light-guiding optical component according to a second aspect of the present invention. FIG. [Figure 34] FIG. 10 is a diagram showing an example of the illuminance distribution in the Y direction (height direction) on the exit surface of a light beam that has entered a second light-guiding optical component of the present invention. [Figure 35] 10 is a diagram showing an example of the distribution of divergence angles in the X direction (width direction) and the Y direction (height direction) on the exit surface of a light beam that has entered a light-guiding optical component according to the second invention. FIG. [Figure 36] 10 is a diagram showing another example of the results of a ray tracing simulation of light rays incident on the light-guiding optical component according to the second invention. FIG. [Figure 37] 10 is a diagram showing another example of the illuminance distribution in the X direction (width direction) on the exit surface of a light beam that has entered the light-guiding optical component of the second invention. FIG. [Figure 38] 10 is a diagram showing another example of the illuminance distribution in the Y direction (height direction) on the exit surface of a light beam that has entered the light-guiding optical component of the second invention. FIG. [Figure 39] 10 is a diagram showing another example of the distribution of divergence angles in the X and Y directions on the exit surface of a light beam that has entered the light-guiding optical component of the second invention. FIG. [Figure 40] 10A and 10B are diagrams showing an example of the results of a ray tracing simulation of light rays incident on the light-guiding optical component according to the third invention. [Figure 41] 10 is a diagram showing an example of an illuminance distribution in the X direction (width direction) on the exit surface of a light beam that has entered a light-guiding optical component according to the third invention. FIG. [Figure 42] FIG. 10 is a diagram showing an example of the illuminance distribution in the Y direction (height direction) on the exit surface of a light beam that has entered a third light-guiding optical component of the present invention. [Figure 43] 10 is a diagram showing an example of the distribution of divergence angles in the X direction (width direction) and the Y direction (height direction) on the exit surface of a light beam that has entered a light-guiding optical component according to the third invention. FIG. [Figure 44] 10 is a diagram showing another example of the results of a ray tracing simulation of light rays incident on the light-guiding optical component according to the third invention. FIG. [Figure 45] FIG. 10 is a diagram showing another example of the illuminance distribution in the X direction (width direction) on the exit surface of the light beam that has entered the light-guiding optical component of the third invention. [Figure 46] FIG. 10 is a diagram showing another example of the illuminance distribution in the Y direction (height direction) on the exit surface of a light beam that has entered the light-guiding optical component of the third invention. [Figure 47] 10 is a diagram showing another example of the distribution of divergence angles in the X and Y directions on the exit surface of a light beam that has entered the light-guiding optical component of the third invention. FIG. [Figure 48] FIG. 10 is a diagram showing an angle β10 formed by a tangent plane at any position of a circular CPC, which is an entrance portion, and the optical axis in the fourth invention. [Figure 49]FIG. 10 is a diagram showing an example of the results of a ray tracing simulation of light rays incident on the light-guiding optical component according to the fourth invention. [Figure 50] FIG. 10 is a diagram showing an example of the illuminance distribution in the X direction (width direction) on the exit surface of a light beam that has entered a light-guiding optical component according to a fourth aspect of the present invention. [Figure 51] FIG. 10 is a diagram showing an example of the illuminance distribution in the Y direction (height direction) on the exit surface of a light beam that has entered a light-guiding optical component according to the fourth aspect of the present invention. [Figure 52] 10 is a diagram showing an example of the distribution of divergence angles in the X direction (width direction) and the Y direction (height direction) on the exit surface of a light beam that has entered a light-guiding optical component according to a fourth aspect of the present invention. FIG. [Figure 53] FIG. 10 is a diagram showing another example of the results of a ray tracing simulation of light rays incident on the light-guiding optical component according to the fourth invention. [Figure 54] FIG. 10 is a diagram showing another example of the illuminance distribution in the X direction (width direction) on the exit surface of the light beam that has entered the light-guiding optical component of the fourth invention. [Figure 55] FIG. 10 is a diagram showing another example of the illuminance distribution in the Y direction (height direction) on the exit surface of a light beam that has entered the light-guiding optical component of the fourth invention. [Figure 56] 10 is a diagram showing another example of the distribution of divergence angles in the X and Y directions on the exit surface of a light beam that has entered the light-guiding optical component of the fourth invention. FIG. [Figure 57] 10 is a diagram showing the illuminance distribution in the X direction (width direction) in the light-guiding optical component according to the first aspect of the invention, when the overall length L is only 1.2 times the diagonal angle D of the exit surface (Example 51). FIG. [Figure 58] 10 is a diagram showing the illuminance distribution in the Y direction (height direction) in the light-guiding optical component according to the first aspect of the invention, when the overall length L is only 1.2 times the diagonal angle D of the exit surface (Example 51). FIG. [Figure 59] FIG. 10 is a diagram showing the illuminance distribution in the X direction (width direction) in a light-guiding optical component according to a third aspect of the present invention, when the overall length L is only 1.8 times the diagonal angle D of the exit surface (Example 52). [Figure 60] FIG. 10 is a diagram showing the illuminance distribution in the Y direction (width direction) in a light-guiding optical component according to the third invention, when the overall length L is only 1.8 times the diagonal angle D of the exit surface (Example 52). [Figure 61] 10 is a diagram showing the illuminance distribution in the X direction (width direction) in a light-guiding optical component according to a second aspect of the present invention, when the total length L is 2.4 times the diagonal angle D of the exit surface (Example 54). FIG. [Figure 62] 10 is a diagram showing the illuminance distribution in the Y direction (width direction) in a light-guiding optical component according to a second aspect of the present invention, when the total length L is 2.4 times the diagonal angle D of the exit surface (Example 54). FIG. [Figure 63] FIG. 10 is a diagram showing the illuminance distribution in the X direction (width direction) in a light-guiding optical component according to a fourth aspect of the present invention, when the total length L is 2.4 times the diagonal angle D of the exit surface (Example 55). [Figure 64] FIG. 10 is a diagram showing the illuminance distribution in the Y direction (width direction) in a light-guiding optical component according to a fourth aspect of the present invention, when the total length L is 2.4 times the diagonal angle D of the exit surface (Example 55). [Figure 65] FIG. 10 is a diagram showing the results of a ray tracing simulation of light rays incident on a light-guiding optical component that integrates a plurality of light-guiding optical components (5 rows and 5 columns) according to the sixth invention. [Figure 66] FIG. 10 is a diagram showing the X-direction illuminance distribution of light rays incident on a light-guiding optical component that integrates a plurality of light-guiding optical components (5 rows and 5 columns) according to a sixth aspect of the present invention. [Figure 67] FIG. 10 is a diagram showing the Y-direction illuminance distribution of light rays incident on a light-guiding optical component that integrates a plurality of light-guiding optical components (5 rows and 5 columns) according to a sixth aspect of the present invention. [Figure 68] FIG. 10 is a diagram showing the change in the X-direction illuminance distribution when the taper angle is increased, with Example 2 being used as a standard. [Figure 69] FIG. 10 is a diagram showing the change in the X-direction illuminance distribution when the taper angle is reduced, with Example 2 being used as a standard. DETAILED DESCRIPTION OF THE INVENTION

[0073] Below, the simulation results of the examples and comparative examples of the first to fourth inventions of the present application are shown, and the obtained data are summarized in tables, and for some results, the obtained data is published as is. [Example]

[0074] Regarding the first invention of the present application, as a means for illuminating a display element (light valve) in a projector, an illumination device using a scattering light source 701 consisting of an LED element and a light-guiding optical component 301 of the first invention of the present application, as shown in FIG. 19, and a projection-type display device using the illumination device were constructed.

[0075] In the simulations that follow, an LED element with a wavelength of 550 nm, a light-emitting surface diameter of 0.255 mm, and a FWHM of ±60° was used as the LED light source. The design wavelength was 550 nm, and the refractive index n of the glass constituting the light-guiding optical component and tapered light tunnel of the present invention was set to 1.5185. Here, glass was selected as the material constituting the light-guiding optical component, but this is not limited to glass and resin may also be used. Note that FWHM refers to the full width at half maximum of the luminance distribution of the LED element.

[0076] In the optical system of FIG. 19, the light-guiding optical component 301 was the first light-guiding optical component of the present invention, which includes a tapered section and a rectangular CPC incident section as shown in FIG. 3, and the existing tapered light tunnel with a truncated quadrangular pyramid shape as shown in FIG. 2. The ray trajectories of the incident light were simulated to determine how they propagate to and exit the exit surface 303 (using the ray-tracing simulation software Ansys Zemax). The results are summarized in Table 1. The FWHM in Table 1 is the full width at half maximum of the divergence angle of the LED light passing through the light-guiding optical component, as determined by the ray-tracing simulation. Regarding the uniformity of the emitted light, a flat illuminance distribution with excellent uniformity is indicated by ◎; a good illuminance distribution with a variation of less than 5% is indicated by ○; a variation of 5% to 10% is indicated by △; and a variation of 10% or more is indicated by ×.

[0077] [Table 1]

[0078] All of the examples in Table 1 relate to the light-guiding optical component of the first invention, and all of the comparative examples relate to the conventional tapered light tunnel. The size of the exit surface was standardized to 2.22 mm x 1.25 mm. The length of the incident portion was changed from 0.4 mm to 0.7 mm, and ray tracing simulations were performed using three sizes of the light-receiving incident surface: 0.3 mm x 0.3 mm, 0.4 mm x 0.4 mm, and 0.7 mm x 0.4 mm. In addition, ray tracing simulations were performed for total length L of the light-guiding optical component, which was 1.5, 2, 3, 4, and 5 times the diagonal length D of the exit surface. On the other hand, for the tapered light tunnel serving as a comparative example, the overall length was set to match that of the light-guiding optical component of the first invention, with the longest length being up to six times the diagonal length D of the exit surface, and the size of the entrance surface was set to three types: 0.3 mm x 0.3 mm, 0.7 mm x 0.4 mm, and 1.1 mm x 0.6 mm. A ray tracing simulation was performed on a shape that uniformly tapered from the entrance surface to the exit surface, with the top and bottom surfaces forming an angle β1 with a horizontal plane including the optical axis and the left and right surfaces forming an angle β2 with a vertical plane including the optical axis.

[0079] Table 2 summarizes the geometric model parameters of the light-guiding optical component of the first invention used in the ray tracing simulation. In addition to the overall length L, the tapered portion length L1, the incident portion length L2, the size of the incident surface H3xW3, and the size of the exit surface H2xW2, the table also lists the taper angle β1, which is the angle between the top and bottom surfaces of the tapered portion and the horizontal direction, and the taper angle β2, which is the angle between the left and right surfaces and the vertical direction. The rectangular CPC-shaped truncated pyramid that constitutes the incident portion of this [Example 1] has an angle β3 between the tangent plane at either the top or bottom surface and the horizontal plane containing the optical axis (see FIG. 20 ), and an angle β4 between the tangent plane at either the left or right surface and the vertical plane containing the optical axis. The horizontal taper angles β1 and β3 satisfy the relationship β3 > β1, while the vertical taper angles β2 and β4 satisfy the relationship β4 > β2.

[0080] [Table 2]

[0081] For example, in Example 2 of Example 1, the total length L of the light-guiding optical component is 5.1 mm, which is twice the diagonal D of the exit surface opening, of which 0.5 mm is the length L2 of the incident portion and 4.6 mm is the length L1 of the tapered portion. The exit surface is 2.22 mm x 1.25 mm. The incident surface size of the incident portion is 0.3 mm x 0.3 mm. The taper angle β1, which is the angle between the top and bottom surfaces of the tapered portion and the horizontal plane containing the optical axis, is 4.3°, and the taper angle β2, which is the angle between the widthwise side surface and the vertical plane containing the optical axis, is 10.0°. In contrast, the minimum and maximum inclination angles of the top and bottom surfaces of the incident portion are 5.2° and 29.2°, respectively, and the minimum and maximum inclination angles of the left and right surfaces are 10.1° and 30.3°, respectively, all of which are larger than the taper angles of the corresponding tapered portions.

[0082] Similarly, the geometric model parameters for the conventional tapered light tunnel for which a ray tracing simulation was performed are summarized in Table 3. The parameters include the ratio of the total length L to the diagonal length D of the exit surface, the total length L, the entrance surface size, the exit surface size, as well as the taper angle β1 of the top and bottom surfaces and the taper angle β2 of the left and right surfaces.

[0083] [Table 3]

[0084] Among the examples shown in Table 1, five out of nine examples (Examples 2, 5, 7, 8, and 9) had extremely excellent uniformity of emitted light (evaluated as ◎ in the table). Three examples (Examples 1, 3, and 6) had a uniformity variation of 5% or less (evaluated as ○ in the table). Only one example (Example 4) had a uniformity variation of 5% or more (evaluated as △ in the table). On the other hand, simulations were performed on 18 examples of conventional tapered light tunnels listed as comparative examples. The only examples with excellent uniformity of illuminance distribution were those whose length was six times the diagonal angle of the emission surface (Comparative Examples 16, 17, and 18). Of these, Comparative Example 18 had a large divergence angle. Among the other comparative examples, Comparative Example 9 and Comparative Example 12 had fair uniformity of illuminance distribution (variation within 5%), but both had a large divergence angle of ±25° or more. In the other comparative examples, the variation in illuminance distribution was at least 5% or more, or even greater.

[0085] FIG. 21 shows the results of a ray tracing simulation for Example 2 in Table 1. The left side of FIG. 21 shows the ray trajectories within the light-guiding optical component, where the ray bundle appears dense. The tapered exit surface is located in the center (a rectangle indicating the exit surface is visible), and the area to the right of the tapered exit surface is outside the light-guiding optical component, where the light beams appear divergent and sparse. FIGS. 22 and 23 show the illuminance distributions in the X- and Y-axis directions on the exit surface obtained from the ray bundle at the position of the tapered exit surface in FIG. 21. FIG. 24 also shows the distribution of radiance in angular space. The distribution of radiance in angular space refers to the luminance that appears distributed in angular space when the light-guiding optical component is viewed from a position away from the exit surface. In the radiance distribution diagram, the thick solid line represents the divergence angle distribution in the X direction, and the dashed-dotted line represents the divergence angle distribution in the Y direction. It can be seen that the shape of the light-guiding optical component of the first invention provides far superior uniformity in illuminance distribution in both the X and Y directions compared to the tapered light tunnel with a truncated quadrangular pyramid shape shown later as a comparative example. Furthermore, from the angular distribution of radiance, it was found that when the light-guiding optical component of the present invention was used, the divergence angle in the X direction (FWHM: full width at half maximum) was kept within a narrow range of ±13.35°, and the divergence angle in the Y direction (FWHM: full width at half maximum) was kept within a narrow range of ±16.97°.

[0086] Regarding the results of the examples of the first invention, in Example 1, where the total length L was only 1.5 times the diagonal angle D of the exit surface, the divergence angle of the emitted light was kept within a low range, and the illuminance distribution in the Y direction was also uniform, but the illuminance distribution in the X direction fluctuated within a range of approximately 3%. With an illuminance distribution of this level, the homogeneity was evaluated as good. In the case where the total length L was twice D, even in Example 3, where the length of the incident portion and the size of the incident surface were larger than in Example 2, a fluctuation of approximately 3% was observed in the X direction illuminance distribution, and in Example 4, a drop in illuminance of nearly 10% was observed in the center of the X direction illuminance distribution. Therefore, in the case where the total length was twice the diagonal angle of the exit surface, Examples 2 and 3 showed good results in all of the X direction illuminance distribution, Y direction illuminance distribution, and divergence angle.

[0087] As another example showing favorable results, the ray tracing simulation results ( FIG. 25 ), X-direction illuminance distribution ( FIG. 26 ), Y-direction illuminance distribution ( FIG. 27 ), and divergence angle distribution ( FIG. 28 ) for Example 7 in Table 1 are shown. The illuminance distribution exhibits excellent uniformity in both the X and Y directions. Furthermore, the radiance divergence angle was narrowed to ±9.69° FWHM (full width at half maximum) in the X direction and ±15.35° FWHM in the Y direction (height direction). The left side of FIG. 25 shows the ray trajectories within the light-guiding optical component, where the ray bundle appears dense. A square appears in the center, indicating the tapered section's exit surface. The area to the right of the tapered section's exit surface is outside the light-guiding optical component, where the light beams appear sparsely diverging from the exit surface. In FIG. 28 , the solid line indicates the divergence angle in the X direction, and the dashed-dotted line indicates the divergence angle in the Y direction.

[0088] From the results of the above examples of the first invention, and with reference to the results of the comparative examples, it was found that when the total length L is 1.5 to 5 times the diagonal length D of the exit surface, uniformity of the illuminance distribution and narrowing of the angle can be achieved stably and reproducibly. Furthermore, from the results shown in Tables 1 and 2, it was found that when the ratio L2 / L1 of the length L2 of the incident portion to the length L1 of the tapered portion is between 2.4% and 13.4%, uniformity of the illuminance distribution and narrowing of the angle can be achieved. It was also found that the taper angle β1 of the tapered portion is in the range of 1.9° to 5.8°, and β2 is in the range of 4.1° to 13.8°. [Comparative Example]

[0089] As a comparative example, a ray tracing simulation was performed (Fig. 29) on Comparative Example 4 in Table 1, a conventional tapered light tunnel, to obtain the X-direction illuminance distribution (Fig. 30) and the Y-direction illuminance distribution (Fig. 31). While there were no problems with the Y-direction illuminance distribution, the X-direction illuminance distribution showed large drops in two locations with a variation of more than 10%, indicating that the illuminance distribution could not be described as homogeneous. The divergence angle was at a level that was virtually problem-free.

[0090] Other results are summarized in Table 1. As described above, the X-direction illuminance distribution and the Y-direction illuminance distribution were evaluated as excellent in uniformity as in Examples 2 and 7, as well as O when the variation in uniformity was within 5%, △ when the variation in uniformity was between 5% and 10%, and × when there was a problem with uniformity (variation of 10% or more) as in Comparative Example 4. Regarding the divergence angle, a value within ±15° was considered to have achieved narrowing of the angle, a value within ±20° was within the acceptable range, and a value exceeding ±20° was evaluated as not having sufficiently narrowed the angle.

[0091] From the results in Table 1, among Comparative Examples 1 to 18, in which ray tracing simulations were performed on conventional tapered light tunnels, only Comparative Examples 16 and 17, which had lengths six times the diagonal length of the exit surface and incident surface sizes of 0.3 x 0.3 mm and 0.7 x 0.4 mm, were able to achieve both a uniform illuminance distribution and a narrow angle. Comparative Example 15, which had a length five times the diagonal length of the exit surface and an incident surface size of 1.1 x 0.6 mm, achieved a uniform illuminance distribution, but the divergence angle reached nearly ±30°, failing to achieve a narrow angle. The same can be said for Comparative Examples 9 and 12. In other words, it was found that the conventional tapered light tunnels could not achieve both a uniform illuminance distribution and a narrow angle unless the total length L was six times the diagonal length D of the exit surface. Conversely, it was found that a uniform illuminance distribution and a narrow angle could not be achieved if the total length L was less than five times the diagonal length D of the exit surface. [Example]

[0092] Next, an example of a light-guiding optical component according to the second aspect of the present invention will be described. Example 1 of the first aspect of the present invention concerns a light-guiding optical component in which an incident section having a rectangular CPC shape as shown in FIG. 8 is formed continuously on the upper surface of a solid truncated square pyramid having taper angles β1 and β2. Example 2 of the present invention, however, shows simulation results for a light-guiding optical component in which an incident section having a general truncated square pyramid shape as shown in FIG. 9 is formed continuously on the upper surface of a first truncated square pyramid having taper angles β1 and β2. The second truncated square pyramid, which is the incident section of Example 2, has taper angles β5 and β6, where the taper angles β1 and β5 in the top-bottom surface direction satisfy a relationship of β5 > β1, and the taper angles β2 and β6 in the left-right surface direction satisfy a relationship of β6 > β2.

[0093] Table 4 lists the parameters related to the shape of the light-guiding optical component used in the simulation, and Table 5 lists the simulation results. The taper angle β1 of the top and bottom surfaces of the tapered portion ranged from 0.8° to 6.3°, and the taper angle β2 of the left and right surfaces ranged from 3.3° to 13.1°. On the other hand, for the truncated quadrangular pyramid of the incident portion, the taper angle β5 of the top and bottom surfaces ranged from 10.7° to 18.7°, and the taper angle β6 of the left and right surfaces ranged from 16.5° to 23.0°, all of which were larger than the taper angle of the tapered portion. The size of the incident surface was 0.3 mm x 0.3 mm, 0.4 mm x 0.4 mm, or 0.7 mm x 0.4 mm, and the length L2 of the incident portion was 0.4 mm to 1.3 mm depending on the total length L. The ratio of the length L2 of the incident portion to the length L1 of the tapered portion ranged from 5.8% to 34.5%.

[0094] When the total length L is three, four, and five times the length D of the diagonal of the exit surface, the uniformity of the illuminance distribution at the exit surface is excellent and the divergence angle is small. When the total length L is twice the length D of the diagonal of the exit surface, the divergence angle is small, but the uniformity of the illuminance distribution at the exit surface varies by about 5%. When the total length L is 1.5 times the length D of the diagonal of the exit surface, the divergence angle is still small, but the uniformity of the illuminance distribution at the exit surface varies by more than 5%. Therefore, from the results shown in Table 5, it was found that in [Example 2], when the total length L is twice the length D of the diagonal of the exit surface (Examples 21, 22, and 23), the uniformity of the illuminance distribution is insufficient, and when the total length L is three times the length D of the diagonal of the exit surface (Examples 25 and 26), both the uniformity of the illuminance distribution and the narrow divergence angle can be satisfied.

[0095] [Table 4]

[0096] [Table 5]

[0097] Two examples of ray tracing simulation results from this [Example 2] are shown below. One is Example 27, where the total length L is 10.2 mm, four times the diagonal length D of the exit surface, the length of the incident portion L2 is 0.8 mm, and L2 / L1 = 8.5%. The ray trajectories are shown in Figure 32, the uniformity in the X direction (width direction) at the exit surface is shown in Figure 33, the uniformity in the Y direction (height direction) is shown in Figure 34, and the divergence angle at the exit surface is shown in Figure 35. The other is Example 21, where the total length L is 3.825 mm, 1.5 times the diagonal length D of the exit surface, the length of the incident portion L2 is 0.4 mm, and L2 / L1 = 11.7%. The ray trajectories are shown in Figure 36, the uniformity in the X direction at the exit surface is shown in Figure 37, the uniformity in the Y direction is shown in Figure 38, and the divergence angle at the exit surface is shown in Figure 39. In Figures 32 and 36, which show ray trajectories, the left side is the ray trajectory inside the light-guiding optical component, where the bundle of rays appears dense. The exit surface of the tapered portion is located in the center (a square indicating the exit surface is visible), and the area to the right of the exit surface of the tapered portion is outside the light-guiding optical component, where the light rays appear divergent and sparse. In Figures 35 and 39, the thick solid line indicates the divergence angle in the X direction, and the thin solid line indicates the divergence angle in the Y direction.

[0098] In Example 27 of [Example 2], the uniformity of the illuminance distribution at the exit surface was excellent as shown in Figures 33 and 34, and the divergence angle was within ±15° as shown in Figure 35, resulting in excellent linearity. On the other hand, in Example 21, although the divergence angle was not a problem as shown in Figure 39, the illuminance distribution at the exit surface varied by 5% or more in both the X and Y directions as shown in Figures 37 and 38, resulting in unsatisfactory uniformity. Other results are shown in Table 5. Examples in which the total length L was three times or more the diagonal length D of the exit surface showed excellent uniformity and a small divergence angle, similar to Example 27. On the other hand, examples in which the total length L was two times or less the diagonal length D of the exit surface showed a small divergence angle but poor uniformity of the illuminance distribution at the exit surface, with a variation of 5% or more, similar to Example 21. [Example]

[0099] Next, we will show an example of a light-guiding optical component according to the third aspect of the present invention. In Example 1 of the first aspect and Example 2 of the second aspect, a light-guiding optical component was described in which a rectangular CPC-shaped entrance section or a general square-prism-shaped entrance section was formed continuously on the upper surface of a solid square-prism truncated pyramid having taper angles β1 and β2. In Example 3, however, we present simulation results for a light-guiding optical component in which an elliptical truncated cone-shaped entrance section, as shown in FIG. 13, is formed continuously on the upper surface of a solid square-prism truncated pyramid having taper angles β7 and β8. The elliptical truncated cone, which is the entrance section of Example 3, has an inclination angle β9 at a position on its slope, and the taper angles β7 and β8 of the tapered section satisfy the relationship β9 > β7, β8. In other words, β9 at a position on its slope is greater than β7 and β8.

[0100] Table 6 lists the parameters related to the shape of the light-guiding optical component used in the simulation, and Table 7 lists the simulation results. The taper angle β7 of the top and bottom surfaces of the tapered portion was 1.2° to 5.0°, and the taper angle β8 of the left and right surfaces was 3.1° to 10.2°. Meanwhile, the inclination angle β9 of the slope of the elliptical truncated cone of the incident portion relative to the optical axis was 17.8° to 42.9° on the major axis side and 12.7° to 18.7° on the minor axis side. Since the inclination angle β9 at the position of the slope includes the slope on the minor axis a3 side and the slope on the major axis b3 side (see Figures 11 and 12), both are listed in Table 6. The size of the incident surface was a circle with a diameter of 0.3 mm, a circle with a diameter of 0.4 mm, and an ellipse with a major axis of 0.7 mm and a minor axis of 0.4 mm. The length L2 of the incident portion was varied between 0.7 mm and 1.9 mm depending on the overall length L. The ratio of the entrance portion length L2 to the tapered portion length L1 is in the range of 14 to 42%.

[0101] [Table 6]

[0102] [Table 7]

[0103] In the cases where the total length L was 3, 4, and 5 times the diagonal length D of the exit surface (Examples 35 to 39), the uniformity of the illuminance distribution at the exit surface was extremely excellent, and the divergence angle was also very small. In the cases where the total length L was twice the diagonal length D of the exit surface (Examples 32 to 34), the divergence angle increased as the incident surface became larger, but was sufficiently small when the incident surface size was 0.3 mmφ and 0.4 mmφ. The uniformity of the illuminance distribution at the exit surface showed a variation of about 5%, but was sufficiently uniform. In the case where the total length L was 1.5 times the diagonal length D of the exit surface (Example 31), the divergence angle remained small, but the uniformity of the illuminance distribution at the exit surface showed a large variation of about 10%.

[0104] The results of a ray tracing simulation for Example 37 are shown in Figure 40. A rectangular plane appears in the middle of the figure, representing the exit surface of the light-guiding optical component of the present invention. The left side of this rectangular plane represents the ray trajectories within the light-guiding optical component, and the right side represents the trajectories of the light rays that exit the exit surface. The illuminance distributions in the X direction (horizontal direction) and Y direction (vertical direction) at the exit surface are shown in Figures 41 and 42. It can be seen that the illuminance distribution at the exit surface is extremely uniform. Figure 43 shows the divergence angle at the exit surface, with the dark solid line representing the X direction and the light solid line representing the divergence angle in the Y direction. Both have extremely small FWHM values ​​of ±7.2° and ±7.5°, demonstrating that a narrow angle has been achieved.

[0105] The results of a ray tracing simulation for Example 31 are shown in Figure 44. As in Figure 40, a rectangular plane appears in the middle of the figure, representing the exit surface of the light-guiding optical component of the present invention. The left side of this rectangular plane represents the ray trajectories within the light-guiding optical component, and the right side represents the trajectories of the light rays exiting the exit surface. The illuminance distributions in the X direction (horizontal direction) and Y direction (vertical direction) at the exit surface are shown in Figures 45 and 46. The illuminance distribution at the exit surface exhibits a variation of approximately 5% in the X direction, and the variation in the Y direction exceeds 10% at the edges. This indicates poor uniformity of the illuminance distribution at the exit surface. Figure 47 shows the divergence angle at the exit surface, with the dark solid line representing the X direction and the light solid line representing the Y direction. The FWHM values ​​were small, at ±12.9° and ±9.4°, indicating no problems with linearity.

[0106] As can be seen from Table 7 for the other Examples, Examples 35, 36, 38, and 39, in which the total length L was three times or more the length D of the diagonal of the exit surface, also showed excellent uniformity of the illuminance distribution at the exit surface, a small divergence angle, and excellent linearity, similar to Example 37, whose results were previously shown. On the other hand, in the case in which the total length L was twice the length D of the diagonal of the exit surface, the illuminance distribution at the exit surface showed a variation of nearly 5%, and the divergence angle was not as small as in Example 37. Examples 32 and 33 were considered to have satisfactory uniformity of the illuminance distribution and divergence angle, but Example 34, in which the entrance surface size was large, had a large divergence angle and was determined to have insufficient performance. [Example]

[0107] Next, an example of a light-guiding optical component according to the fourth aspect of the present invention will be described. In Example 3, which is an example of the third aspect of the present invention, the simulation results were for a light-guiding optical component in which an incident section having an elliptical truncated cone shape, i.e., the shape shown in FIG. 13, is continuously formed on the top surface of a solid truncated square pyramid with taper angles β7 and β8. However, the incident section in Example 4 has a circular CPC shape, as shown in FIG. 15, in which the incident surface of the incident section is circular, the bottom is square, and the slope is a CPC (an internal reflection paraboloid). The tapered section is the same as that shown in Example 3, a solid truncated square pyramid with taper angles β7 and β8. That is, a simulation was performed for a light-guiding optical component in which a circular CPC incident section is continuously formed on the tapered section of a solid truncated square pyramid. In this case, the inclination angle β of the tangent plane at any position on the slope of the circular CPC of the incident section is 10 Between the taper angle of the tapered section and 10 >β7, β8. That is, β 10 is greater than β7 and β8 (see FIG. 48).

[0108] The parameters relating to the shape of the light-guiding optical component used in the simulation are shown in Table 8, and the simulation results are shown in Table 9. The taper angle β7 of the top and bottom surfaces of the tapered portion is 0.5° to 5.3°, and the taper angle β8 of the left and right surfaces is 3.0° to 11.2°. On the other hand, for the circular CPC at the entrance, the inclination angle β 10 The maximum angle is at the position adjacent to the entrance surface, and the minimum angles are at the horizontal and vertical ends. These angles are also listed in Table 8. The entrance surface size was a circle with a diameter of 0.3 mm, a circle with a diameter of 0.4 mm, or a circle with a diameter of 0.5 mm. The entrance section length L2 was varied between 0.8 mm and 1.5 mm depending on the total length L. The ratio of the entrance section length L2 to the tapered section length L1 was in the range of 11% to 42%.

[0109] [Table 8]

[0110] [Table 9]

[0111] In cases where the total length L was 3, 4, and 5 times the length D of the diagonal of the exit surface (Examples 44 to 49), the uniformity of the illuminance distribution at the exit surface was extremely excellent and the divergence angle was also small. In cases where the total length L was twice the length D of the diagonal of the exit surface (Examples 42 and 43), the uniformity of the illuminance distribution at the exit surface varied by about 5%, and the divergence angle was also slightly large. In cases where the total length L was 1.5 times the length D of the diagonal of the exit surface (Example 41), the uniformity of the illuminance distribution at the exit surface varied by about 10%, and the divergence angle exceeded ±15°.

[0112] For Example 47, the results of a ray tracing simulation, the illuminance distribution in the X and Y directions on the exit surface, and the divergence angle at the position of the exit surface are shown in Figures 49, 50, 51, and 52, respectively. It can be seen that the illuminance distribution is highly uniform, the divergence angle is small, and the linearity is excellent.

[0113] Next, for Example 42, the results of a ray tracing simulation, the illuminance distribution in the X and Y directions on the exit surface, and the divergence angle at the position of the exit surface are shown in Figures 53, 54, 55, and 56, respectively. The illuminance distribution on the exit surface showed a variation of about 5% in both the X and Y directions. The divergence angle was about ±10°, which was at an acceptable level. [Example]

[0114] From the results of [Example 1], [Example 2], [Example 3], and [Example 4] above, when the incident part was a rectangular CPC, a second truncated square pyramid, an elliptical truncated cone, or a circular CPC, there were examples in which the results were good and examples in which the results were unsatisfactory, but it was found that the boundary between these two can be distinguished by the ratio (L / D) of the total length L to the diagonal length D of the exit surface. When the incident part was a rectangular CPC, the results were good even when L / D was 1.5, so it is thought that the results became unsatisfactory when L / D was 1.5 or less. When the incident part was a second truncated square pyramid, the results were good when L / D was 3, but when L / D was 2, although the divergence angle was small, the uniformity of the illuminance distribution on the exit surface was insufficient, so it is thought that the boundary lies between L / D 2 and 3. When the entrance section was an elliptical truncated cone, good results were obtained when L / D was 2 or greater. However, when L / D was 1.5, the divergence angle was small, but the uniformity of the illuminance distribution at the exit surface became insufficient. Therefore, the boundary is considered to be between L / D 1.5 and 2. When the entrance section was a circular CPC, good results were obtained when L / D was 3 or greater. However, when L / D was 2 or less, the divergence angle was small, but the uniformity of the illuminance distribution at the exit surface became insufficient. Therefore, the boundary is considered to be between L / D 2 and 3. Therefore, to determine the boundary values ​​for these L / Ds, additional simulations were performed. The shape model parameters used in the additional simulations are shown in Tables 10 and 11, and the simulation results are shown in Table 12.

[0115] [Table 10]

[0116] [Table 11]

[0117] [Table 12]

[0118] In Example 51, in which the incident portion was a rectangular CPC and the total length L was 1.2 times the diagonal angle D of the exit surface, the X-direction illuminance distribution and the Y-direction illuminance distribution at the exit surface both varied by 10% or more, as shown in Figures 57 and 58, and were not uniform. In Example 52, in which the incident portion was an elliptical truncated cone and the total length L was 1.8 times the diagonal angle D of the exit surface, the divergence angle at the exit surface was good, but as shown in Figures 59 and 60, the X-direction illuminance distribution and the Y-direction illuminance distribution both varied by 5% or more, and were not sufficiently uniform. In contrast, in Examples 53 and 54, in which the incident portion was a square truncated pyramid and the total length L was 2.4 times the diagonal angle D of the exit surface, both the divergence angle was small and the variation in the X-direction illuminance distribution and the Y-direction illuminance distribution was less than 5%, resulting in excellent uniformity. The results for Example 54 are shown in Figures 61 and 62. In Examples 55 and 56, in which the incident portion was a circular CPC and the total length L was 2.4 times the exit surface diagonal D, the divergence angle was small in both cases, and the variations in the X-direction illuminance distribution and the Y-direction illuminance distribution were 5% or less, resulting in excellent uniformity. The results for Example 55 are shown in Figures 63 and 64.

[0119] The evaluation results for the above boundary values ​​revealed the following: When the entrance part is a rectangular CPC, good results are obtained in both the uniformity of the illuminance distribution at the exit surface and the narrowing of the divergence angle when L / D is between 1.5 and 5, but uniformity deteriorates when L / D is 1.2. When the entrance part is an elliptical truncated cone, good results are obtained in both the uniformity of the illuminance distribution at the exit surface and the narrowing of the divergence angle when L / D is between 2 and 5, but uniformity deteriorates when L / D is 1.8. When the entrance part is a square truncated pyramid, good results are obtained in both the uniformity of the illuminance distribution at the exit surface and the narrowing of the divergence angle when L / D is between 2.4 and 5, but uniformity deteriorates when L / D is 2.0. Even when the incident part is a circular CPC, good results are obtained in terms of the uniformity of the illuminance distribution on the exit surface and the narrowing of the divergence angle when L / D is 2.4 to 5, but the uniformity deteriorates when L / D is 2.0. [Example]

[0120] Next, the light-guiding optical components according to Example 5 of the first invention of the present application, as shown in Table 1, were arranged in five vertical rows and five horizontal rows without any gaps, resulting in a light-guiding optical component integrated with five rows and five horizontal rows of light-guiding optical components. An LED element was then placed on the incident surface of each of the five rows and five horizontal rows of light-guiding optical components to obtain a surface-emitting lighting device. A ray-tracing simulation (FIG. 65) was then performed to evaluate the illuminance distribution at the exit surface of the surface-emitting lighting device (FIGS. 66 and 67). The left side of FIG. 65 shows the ray trajectories within the light-guiding optical component, with the ray bundle appearing densely. The tapered exit surface (a square indicating the exit surface) is located in the center, while the area to the right of the tapered exit surface is outside the light-guiding optical component, with the light beams appearing divergent and sparsely dispersed from the exit surface. Looking at the illuminance distribution in the X and Y directions, slight non-uniformity is observed due to the influence of stray light, presumably from adjacent light-guiding optical components, due to the contact between the light-guiding optical components. It is believed that such non-uniformity can be avoided by arranging each light-guiding optical component at intervals of approximately 0.1 mm to 0.3 mm. Furthermore, it is believed that by placing a condenser lens behind such a light source, the uniformity of the light incident on the display device (light valve) of the projection display device will be at a level that does not pose any problems. [Example]

[0121] Next, to examine the effects of taper angles β1 and β2, we used Examples 2 and 4 in Table 1 for Example 1 as standard models. We investigated the effects of increasing the taper angle to enlarge the exit surface and decreasing the taper angle to reduce the exit surface. The results are shown in Table 13. The parameters used in the simulation are shown in Table 14. The uniformity of the illuminance distribution significantly deteriorated when the taper angle of Example 2 was increased to enlarge the exit surface (FIG. 68) and when the taper angle was decreased to reduce the exit surface (FIG. 69). The illuminance distribution also significantly deteriorated when the taper angle of Example 4 was increased to enlarge the exit surface. On the other hand, when the taper angle of Example 4 was decreased to reduce the exit surface, the uniformity of the illuminance distribution improved somewhat, but the divergence angle became extremely large, and a narrower angle was not achieved. In this study, no taper angle was found that could further improve the results of Examples 2 and 4 listed in Table 1.

[0122] [Table 13]

[0123] [Table 14]

[0124] Next, to investigate the effect of changing the length L2 of the incident section on the illuminance distribution and divergence angle, simulations were performed using Example 2 in Table 1 for Example 1 as the standard model, with the incident section shortened (Example 15) and lengthened (Example 16). The simulation results are shown in Table 13, and the parameters used in the simulation are shown in Table 15. The homogeneity (illuminance distribution) of the emitted light significantly deteriorated whether the incident section length was shortened or lengthened. When the length was shortened, the illuminance distribution in the X direction significantly increased near the center, while when the length was lengthened, the illuminance distribution in the X direction significantly decreased near the center. In other words, in this study, there was no incident section length longer than Example 2.

[0125] [Table 15]

[0126] [summary] All the data from the simulation is summarized in Table 16. As stated above, the following points can be concluded: (1) In the conventional tapered light tunnel, unless the total length of the tapered light tunnel is at least six times the diagonal length of the exit surface, it is not possible to achieve a uniform illuminance distribution and a narrow divergence angle at the exit surface for the light incident from the entrance surface. (2) When an incident section made of a rectangular CPC is provided contiguous to the tapered section, and the angles (β3 and β4) formed by the tangent planes of the rectangular CPC and the optical axis at both the top and bottom and left and right sides of the rectangular CPC are set larger than the corresponding taper angles (β1 and β2) of the tapered section, a uniform illuminance distribution and a narrow divergence angle can be achieved at the exit surface of the light incident from the incident surface, even with a short overall length (L) of 1.5 to 5 times the diagonal angle D of the exit surface of the tapered section, thereby achieving high performance and a compact light-guiding optical component. In this case, the ratio L2 / L1 of the incident length to the tapered section length is in the range of 2.4% to 13.4%, the top and bottom surface angle β1 of the tapered section is in the range of 1.9° to 5.8°, and the left and right surface angle β2 of the tapered section is in the range of 4.1° to 13.8°. (3) When an incident section consisting of a second truncated quadrangular pyramid is provided contiguous with the tapered section, and the angles (β5 and β6) formed by the upper and lower side surfaces and the left and right side surfaces forming the second truncated quadrangular pyramid with the horizontal and vertical planes containing the optical axis are set larger than the corresponding tapered section taper angles (β1 and β2), the overall length (L) can be as short as 2.4 to 5 times the diagonal angle D of the tapered section exit surface, resulting in a high-performance, compact light-guiding optical component. In this case, the ratio L2 / L1 of the incident section length to the tapered section length is in the range of 5.8% to 19.6%, the tapered section upper and lower surface angle β1 is in the range of 1.1° to 3.3°, and the tapered section left and right surface angle β2 is in the range of 3.3° to 6.4°. (4) When an incident section made of an elliptical truncated cone is provided adjacent to the tapered section, and the angle (β9) between the inclination angle of the elliptical truncated cone and the optical axis at any position on the slope of the elliptical truncated cone is set to be larger than the taper angles (β7 and β8) of the tapered section, the overall length (L) can be kept short, between two and five times the diagonal angle D of the tapered section's exit surface, to achieve a uniform illuminance distribution and a narrow divergence angle at the exit surface of the light incident from the incident surface, thereby enabling a light-guiding optical component to be made compact and high-performance. In this case, the ratio L2 / L1 of the incident section length to the tapered section length is in the range of 14.2% to 41.6%, the tapered section's top and bottom surface angle β7 is in the range of 1.2° to 4.2°, and the tapered section's left and right surface angle β8 is in the range of 3.1° to 7.3°. (5) When the entrance part of a circular CPC is provided continuously to the tapered part, the angle (β 10 ) is set to be larger than the taper angles (β7 and β8) of the tapered portion, the overall length (L) is kept short, at 2.4 to 5 times the diagonal angle D of the tapered portion's exit surface, and yet it is possible to achieve a uniform illuminance distribution on the exit surface and a narrow divergence angle, thereby enabling a light-guiding optical component with high performance and miniaturization. In this case, the ratio L2 / L1 of the entrance length to the tapered portion length is in the range of 11.3% to 16.7%, the tapered portion's top and bottom surface angle β7 is in the range of 0.5° to 3.5°, and the tapered portion's left and right surface angle β8 is in the range of 3.0° to 8.1°. (6) By arranging a plurality of light-guiding optical components as described in (2) to (5) above, it is possible to obtain a light-guiding optical component with a uniform illuminance distribution over a wide light-emitting surface and a small divergence angle. (7) By arranging an LED light source in contact with the incident surface of the light-guiding optical component described in (2) to (6) above, it is possible to obtain a lighting device with a uniform illuminance distribution and a small divergence angle. (8) By using the illumination device described in (7) above, lens means, light valve, magnifying optical lens system, and screen, a projection display device with a uniform illuminance distribution with little color unevenness can be obtained.

[0127] [Table 16] [Explanation of symbols]

[0128] 101 Square pillar light tunnel 102....Inlet surface of rectangular prism-shaped light tunnel 103....Exit surface of rectangular prism-shaped light tunnel 104...Side of rectangular pillar-shaped light tunnel 201 Tapered Light Tunnel 202....Tapered Light Tunnel Entrance Surface 203....Tapered light tunnel exit surface 204 Tapered Light Tunnel Side 301: An example of the light-guiding optical component of the present invention 302: Incident surface of an example of the light-guiding optical component of the present invention 303: Exit surface of an example of the light-guiding optical component of the present invention 304: Left and right side surfaces of the tapered portion of an example of the light-guiding optical component of the present invention 305: Upper and lower side surfaces of the tapered portion of an example of the light-guiding optical component of the present invention 306: The upper surface of the tapered portion (also the bottom surface of the incident portion) of the light-guiding optical component of the present invention 307: Upper and lower side surfaces (or side surfaces) of the incident portion of an example of the light-guiding optical component of the present invention 308... Left and right side surfaces of the incident portion of an example of the light-guiding optical component of the present invention 309: An example of a lens portion of an example of the light-guiding optical component of the present invention 310: An exit surface of an example of a lens portion of an example of a light-guiding optical component of the present invention 701...LED light source 702···Condenser lens 703 Primary lens 704 Light valve 705...Reflector 706 Enlarged projection unit

Claims

1. Height H １ , width W １ Rectangle (H １ =W １ When the incident surface is square, the height H ２ , width W ２ The rectangular exit surface (H ２ >H １ , W ２ >W １ ) at an angle β in the height direction with respect to the optical axis １ , angle β in the width direction ２ The length L is a truncated quadrangular pyramid that spreads in the direction of light propagation. １ and a solid tapered portion having a height H １ and width W １ The square or rectangle has a base of height H ３ , width W ３ Rectangle (H ３ =W ３ A rectangular CPC having a top surface of length L ２ The upper and lower side surfaces and the left and right side surfaces constituting the rectangular CPC are all internal reflection type compound paraboloids, and the angle β between the tangent plane and the horizontal plane including the optical axis at any position on the upper and lower side surfaces is ３ is the above β １ and the angle β between the tangent plane and the vertical plane including the optical axis at any position on the left and right side surfaces is larger than ４ is the above β ２ and the length L of the tapered portion １ and the length L of the rectangular CPC ２ The sum (total length L) of the solid tapered portion and the solid incident portion is 1.5 to 5 times the diagonal length D of the exit surface of the tapered portion.

2. 2. The light-guiding optical component according to claim 1, wherein the length L of the rectangular CPC is ２ is the length L of the tapered portion １ A light-guiding optical component characterized in that the range is 2.4% to 13.4% of the above.

3. 2. The light-guiding optical component according to claim 1, wherein the β １ is in the range of 1.9° to 5.8°, and the β ２ A light-guiding optical component characterized in that the angle is in the range of 4.1° to 13.8°.

4. Height H １ , width W １ Rectangle or square (H １ =W １ When the incident surface is ２ , width W ２ The rectangular exit surface (H ２ >H １ , W ２ >W １ ) at an angle β in the height direction with respect to the optical axis １ , angle β in the width direction ２ The first truncated quadrangular pyramid has a length L １ and a solid tapered portion having a height H １ and width W １ The square or rectangle has a base of height H ３ , width W ３ A second solid truncated square pyramid having a square or rectangular top surface of length L ２ The four side surfaces of the second truncated quadrangular pyramid are flat trapezoids, and the trapezoids on the upper and lower sides form an angle β with the horizontal plane including the optical axis at any position. ５ is the above β １ The angle β between the trapezoid on the left and right sides and the vertical plane including the optical axis at any position is larger than the angle β ６ is the above β ２ and the length L of the tapered portion １ and the length L of the second truncated quadrangular pyramid ２ The sum (total length L) of the above is 2.4 to 5 times the diagonal length D of the exit surface of the tapered portion which is the first truncated quadrangular pyramid.

5. 5. The light-guiding optical component according to claim 4, wherein the length L of the second truncated quadrangular pyramid is ２ is the length L of the tapered portion １ A light-guiding optical component characterized in that the range is 5.8% to 19.6% of the above.

6. 5. The light-guiding optical component according to claim 4, wherein the β １ is in the range of 1.1° to 3.3°, and the β ２ is in the range of 3.3° to 6.4°.

7. Height a １ , width b １ From the rectangular entrance surface of ２ , width W ２ The rectangular exit surface (H ２ >a １ , W ２ >b １ ) at an angle β in the height direction with respect to the optical axis ７ , angle β in the width direction ８ The length L is a solid truncated square pyramid that spreads in the direction of light. １ and further having a tapered portion of the height a １ , width b １ The rectangle has a base and a minor axis a ３ , major axis b ３ The length L of the elliptical truncated cone with the ellipse as the upper surface ２ The incident portion of the elliptical truncated cone is formed continuously with the tapered portion, and the angle β between the inclined surface and the optical axis at any position of the elliptical truncated cone ９ However, the β ７ and β ８ and the length L of the tapered portion １ and the length L of the elliptical truncated cone ２ The sum (total length L) of the above is 2 to 5 times the diagonal length D of the exit surface of the tapered portion.

8. 8. The light-guiding optical component according to claim 7, wherein the length L of the elliptical truncated cone ２ is the length of the tapered part L １ A light-guiding optical component characterized in that the range is 14.2% to 41.6% of the above.

9. 8. The light-guiding optical component according to claim 7, wherein the β ７ is in the range of 1.2° to 4.2°, and the β ８ A light-guiding optical component characterized in that the angle is in the range of 3.1° to 7.3°.

10. Height a １ , width a １ From the square entrance surface of ２ , width W ２ The angle β in the height direction with respect to the optical axis is ７ , angle β in the width direction ８ A truncated pyramid of length L that flares out at the end １ The tapered portion has a height a １ , width b １ The rectangle has a base and a top surface with a diameter of a ３ and the length L consisting of a circular CPC with an internally reflecting parabolic surface. ２ The angle β between the tangent plane and the optical axis at any position on the side surface of the incident portion is １０ is the β ７ and β 8 and the length L of the tapered portion １ and the length L of the circular CPC ２ The sum (total length L) of the above is 2.4 times or more and 5 times or less the diagonal length D of the exit surface of the tapered portion.

11. 11. The light-guiding optical component according to claim 10, wherein the length L of the circular CPC ２ is the length of the tapered part L １ A light-guiding optical component characterized in that the range is 11.3% to 16.7% of the above.

12. 11. The light-guiding optical component according to claim 10, wherein the β ７ is in the range of 0.5° to 3.5°, and the β ８ A light-guiding optical component characterized in that the angle is in the range of 3.0° to 8.1°.

13. 11. The light-guiding optical component according to claim 1, wherein a lens having a light-condensing or diverging effect is integrated at the position of the light-emitting surface of the tapered portion.

14. A light-guiding optical component in which a plurality of light-guiding optical components according to claim 1 are arranged and integrated.

15. A light-guiding optical component in which a plurality of light-guiding optical components according to claim 4 are arranged and integrated.

16. A light-guiding optical component in which a plurality of light-guiding optical components according to claim 7 are arranged and integrated.

17. A light-guiding optical component in which a plurality of light-guiding optical components according to claim 10 are arranged and integrated.

18. 18. An illumination device that emits light by bringing an LED optical element into contact with the incident surface of the incident portion of the light-guiding optical component according to claim 1, 4, 7, 10, 14, 15, 16 or 17.

19. 20. A projection display device comprising the lighting device of claim 18, lens means, a light valve, a magnifying optical lens system, and a screen, wherein light from an LED element that reaches an exit surface of a light-guiding optical component of said lighting device is condensed by the lens means to illuminate the light valve, and an output image generated by the light valve is magnified by the magnifying optical system and projected onto the screen.

Images