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 aims to effectively utilize the light beam from an LED light source, and enables a display element (also referred to as a light valve) such as a transmissive liquid crystal display element, a reflective liquid crystal display element, and a DMD (Digital Micromirror Device) display element to be illuminated with the same brightness uniformly in the plane. The present invention relates to a light guide optical component for a light beam from a light source, an illumination device using the light guide optical component, and a projection display device (also referred to as a projector) using the illumination device.

Background Art

[0002] Data projectors are widely used as image projection devices that project screen display images, video images, etc. of personal computers onto a screen. In recent years, "smart projectors" that can access a website and project videos with a single projector, and "ultra-small projectors" the size of a palm, etc., are also becoming popular for uses different from conventional presentations.

[0003] Some projectors use an ultra-high pressure mercury lamp, LED, laser, etc. as a light source. In recent years, the number of projectors using an LED as a light source has increased because of its long lifespan and little temperature rise. And, except for types that directly draw on a screen with a scanning laser, in many projectors, a light valve, which is a display element, is illuminated, and the video reproduced by controlling light by "on" and "off" of the display element is projected onto the screen.

[0004] In addition to a general color projector using a display element that reproduces video with separate display elements corresponding to RGB three colors and overlaps the light with video information, there is also a method of projecting three-color videos onto a screen in a time-sharing manner by illuminating one display element with RGB three colors in a time-sharing manner.

[0005] For images projected onto a screen to be bright and uniform, it is important to capture as much light as possible from the light source and to illuminate the display elements uniformly. Therefore, measures are taken to ensure that the display elements are illuminated with uniform illuminance using light emitted from the light source.

[0006] Methods for uniformly illuminating display elements mainly involve using fly-eye lenses or light tunnels.

[0007] In an optical system using fly-eye lenses, two fly-eye lenses and a condensing lens are combined to project the real images of each cell of the first fly-eye lens onto the display element, averaging the light distribution and illuminance distribution of each cell to achieve a uniform light distribution.

[0008] In a light distribution homogenization optical system using a light tunnel, the intensity at the exit surface is homogenized by the repeated reflection of incident light inside the light tunnel. By projecting this homogenized light distribution real image onto a display element, the display element is illuminated with uniform intensity.

[0009] If the angle between the light illuminating these display elements and the optical axis becomes large, disadvantages such as reduced light utilization efficiency and difficulty in miniaturizing the optical system for projecting images from the display elements occur. Therefore, in optical systems that illuminate these display elements with uniform illumination, many designs incorporate features to minimize the angle between the light illuminating the display elements and the optical axis.

[0010] A method using a rod lens has been proposed as a way to uniformly illuminate display elements (Patent Document 1). According to this method, the rod lens not only serves to guide the light emitted from the light source to the polarizing plate in the subsequent process, but also repeatedly reflects off the inner surface of the rod lens as the light passes through it, and the light reflected at various angles is superimposed on the output surface of the rod lens, thereby homogenizing the illuminance distribution of the light.

[0011] To enable efficient use of emitted light and the acquisition of bright projected images, even when using light sources with a large divergence angle of emitted light, such as LED light sources, 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 that widen towards the bottom to reduce 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 Publication No. 2003-329978 [Patent Document 2] Japanese Patent Publication 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 Publication No. 2004-252112 [Patent Document 7] Japanese Patent Publication No. 2009-31717 [Patent Document 8] Japanese Patent Publication No. 2011-133899 [Patent Document 9] Special Publication No. 2009-544063 [Patent Document 10] Japanese Patent Publication No. 2007-199163 [Patent Document 11] Japanese Patent Publication No. 2007-288169 [Overview of the project] [Problems that the invention aims to solve]

[0013] In the solid light tunnel 101 with a square prism shape shown in FIG. 1, when the light beam incident from the incident surface 102 guides the light inside while undergoing total reflection on the side surface 104, the angle formed by the light beam with the optical axis does not change. Therefore, the angle formed by the light beam emitted from the exit surface 103 with the optical axis is the same as the angle formed by the incident light with the optical axis.

[0014] On the other hand, when a light beam forming an angle with the optical axis is incident on the incident surface 202 of the solid tapered light tunnel 201 having a frustum of a square pyramid shape with a taper shown in FIG. 2, while the light beam captured from the incident surface 202 travels toward the exit surface 203, the angle formed by the light beam with the optical axis becomes smaller each time it is reflected by the inclined side surface 204 of the light tunnel.

[0015] Patent Document 3 discloses a light guide device having a substantially square pyramid shape with a side surface being a paraboloid (a non-imaging curved surface). This is for obtaining a substantially parallel light beam at the exit surface of the light guide device.

[0016] Also in Patent Document 4, a light guide with a flare is used for the same reason. Among them, as an example, a light guide having a tapered portion and a parallel portion, which combines a frustum of a cone and a cylinder or combines a frustum of a cone and a hexagonal prism, is disclosed.

[0017] Patent Document 5 discloses a partial tapered rod that combines a square prism and a frustum of a square pyramid or combines a square prism and a frustum of a cone. By controlling the taper angle of this partial tapered rod, the parallelism of the converging light beam from the light source lamp is set to a desired value, the spread angle of the illumination light beam is reduced, and it is stated that a relay optical system for forming an image on the illuminated surface can be made compact.

[0018] However, if the length of the tapered light tunnel 201 is not sufficient with respect to the size of the exit surface 203, light beams with a small angle at the time of incidence on the incident surface 202 cannot obtain a sufficient number of reflections, and light beams with a large angle at the time of incidence on the incident surface 202, although having a relatively large number of reflections, still have a large angle with the optical axis even when reaching 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 from the side surfaces 204 of the tapered light tunnel are necessary. Therefore, it is generally necessary to aim to increase the number of reflections by guiding high NA (NA is numerical aperture) focused or divergent light to the incident surface 202. On the other hand, when introducing low NA focused or divergent light, which consists of many rays with small angles to the optical axis, it is necessary to use a long light tunnel to increase the number of reflections.

[0020] On the other hand, while a shorter tapered light tunnel is desirable for miniaturizing the optical system, achieving uniform light distribution at the exit surface 203 with a short light tunnel requires inducing high NA converged and divergent light, 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 port 203 tends to be. However, since a higher number of reflections is advantageous for achieving uniform light distribution intensity at the exit surface 203, a large angle between the side surface 204 of the tapered light tunnel and the optical axis tends to result in uneven light distribution at the exit port 203. In other words, under a given length of light tunnel, it is thought that there is an appropriate range for the angle (inclination angle) that the side surface 204 of the tapered light tunnel makes with the optical axis.

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

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

[0024] Patent Document 7 provides an optical system unit having a light guide device capable of emitting a beam of light 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 the light source side optical system. This light tunnel has four substantially rectangular plates forming the top, bottom, left, and right surfaces, and is formed into a substantially truncated square pyramidal shape by overlapping and fixing the top and bottom plates to the sides of the side plates which are arranged diagonally opposite to each other. As a result, the side plates are formed diagonally so that the area of ​​the exit surface is larger than the area of ​​the incident surface of the light tunnel, so that the angle of the beam of light in the lateral direction can be brought closer to a beam of light parallel to the optical axis. However, as already mentioned, simply using a light tunnel that is arranged diagonally does not allow for both the homogeneity of light and the reduction of the divergence angle to be achieved.

[0025] Patent Document 8 relates to a light guide device and a projector, and in order to capture more of the light beam emitted from the light source device and to emit light beams with a large angle to the optical axis as light beams with a gentler angle, it comprises a cylindrical light tunnel with a rectangular parallelepiped shape and a hollow interior and a glass rod, the light tunnel has one end of the opening as the entrance port and the other end as the exit port side, and has a reflective surface on its inner surface so that the internal space is a light guide path, and the glass rod has a flared inclined portion that extends from the entrance port side to the exit port side, and the inclined portion is placed in the light guide path of the light tunnel so that the bottom surface of the glass rod is the light emission outlet. However, according to this invention, since the light guide device consists of a hollow cylindrical light tunnel with a reflective surface on its inner surface and a glass rod with a flared inclined portion that extends towards the end, the problem of the light guide device being complex and expensive cannot be avoided.

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

[0027] Patent Document 10 aims to efficiently equalize illumination unevenness on the emission surface without extending the overall length when guiding diffused light to an optical member having an optical surface parallel to the optical axis, and provides a light guide member that guides diffused light emitted from a light source to an optical member having an optical surface parallel to the optical axis, comprising a plurality of tapered rod portions arranged adjacently along the central axis passing through approximately the center of the incident end and the emission end between the incident end located on the light source side and the emission end located on the optical member side, wherein each tapered rod portion has a shape that gradually widens at a constant taper angle from the incident end to the emission end side, and the taper angle of each tapered rod portion is set to be smaller than the taper angle of the tapered rod portion adjacent to the incident end side.

[0028] Patent Document 11 describes an optical element that offers excellent light utilization efficiency and can be miniaturized, thinned, and lightweight with a simple configuration, as well as a lighting device and an image display device using the same. The optical element comprises a light source composed of a set of multiple colors of light-emitting devices that can emit multiple colors of light and selectively emit light from desired elements, and a rod lens array in which rod lenses made of a material transparent to the light source have a first surface having an area equal to or greater than the area of ​​the light source and a second surface facing the first surface, and these two surfaces are arranged in a two-dimensional array with the two surfaces as the base. In this configuration, the light source composed of a set of multiple colors of light-emitting devices is placed on the first surface side of each rod lens of the rod lens array, thereby homogenizing the illuminance of each color of light on the second surface of the rod lens array by homogenizing the illuminance of the light emitted from the light source at each rod lens.

[0029] The problem that this invention aims to solve is to provide a light guide optical component that can capture even more light from an LED light source than conventional technology, has a uniform luminous intensity, irradiates a light bulb with a small divergence angle, and is more compact than conventional technology, as well as a lighting device using the light guide optical component and a projection-type image display device using the lighting device. [Means for solving the problem]

[0030] To solve the above-mentioned conventional problems, the first invention of this application has a solid tapered portion of length L1 that is a frustoconical pyramid that widens in the direction of light propagation at an angle β1 in the height direction and an angle β2 in the width direction with respect to the optical axis, extending from an incident surface of a rectangle with height H1 and width W1 (a square when H1=W1) toward an exit surface of a rectangle with height H2 and width W2 (H2>H1, W2>W1), and further comprises a solid incident portion of length L2 that is a rectangular CPC having a square or rectangle of height H1 and width W1 as its base and a rectangular upper surface of height H3 and width W3 (a square when H3=W3), and the rectangular CPC is formed continuously. The upper and lower sides and left and right sides are all made of internally reflective composite paraboloids, and at any position on the upper and lower sides, the angle β3 that the tangent plane makes with the horizontal plane containing the optical axis is greater than β1, and at any position on the left and right sides, the angle β4 that the tangent plane makes with the vertical plane containing the optical axis is greater than β2, and the sum of the length L1 of the tapered portion and the length L2 of the rectangular CPC (total length L) is at least 1.5 times the length D of the diagonal of the exit surface of the tapered portion, which is a frustum of a square pyramid that widens at the bottom and has a height H2 and a width W2. This is a light-guiding optical component consisting of a solid tapered portion and a solid incident portion.

[0031] Here, a rectangular CPC is a truncated pyramid-like shape consisting of a top surface, a bottom surface, and four sides, in which all four sides are internally reflective composite parabolas. Light enters from the top surface of the solid incident portion of the rectangular CPC, is reflected by the top and bottom sides and the left and right sides, and proceeds from the bottom surface to the incident surface of the tapered portion which is the flared truncated pyramid, is repeatedly reflected by the sides of the tapered portion, and proceeds to the exit surface before being emitted. When β3 is greater than β1 and β4 is greater than β2, it means that before the light enters the tapered portion which is the flared truncated pyramid, it is reflected in the incident portion of the rectangular CPC so that the direction of light propagation approaches the optical axis.

[0032] In other words, in such a light-guiding optical component, light incident on the top surface, which is a rectangle or square with height H3 and width W3, is reflected off the four sides of the rectangular CPC (top, bottom, left, and right sides), changing direction significantly, reaching the bottom surface of the rectangular CPC with height H1 and width W1, then incident on the tapered section, which is a frustoconical pyramid that widens towards the bottom, and after repeated reflections off the sides of the tapered section, reaches the rectangular exit surface with height H2 and width W2, and exits from the exit surface.

[0033] Furthermore, as revealed by the ray tracing simulation described later, if the sum of the length L1 of the tapered portion and the length L2 of the rectangular CPC (total length L) is at least 1.5 times the length D of the diagonal of the exit surface of the tapered portion, which is a frustoconical pyramid with height H2 and width W2, then the illuminance distribution of the light rays at the exit surface of the tapered portion becomes stable and homogeneous, and the divergence angle of the light rays radiating from the exit surface becomes stable and small, that is, the straightness also increases. At that time, the length L2 of the rectangular CPC is in the range of 2.4% to 13.4% of the length L1 of the tapered portion, β1 is in the range of 1.9° to 5.8°, and β2 is in the range of 4.1° to 13.8°. Note that the size of the rectangular exit surface with height H2 and width W2 is equal to, or at least similar to, the size of the display element irradiated by the light guide optical component of the present invention.

[0034] Figure 3 illustrates an example of the configuration of the light guide optical component of the first invention. 301 is the overall view, and it can be described as a light tunnel having a double taper structure consisting of an incident portion which is a rectangular CPC and a tapered portion which is a frustum of a square pyramid. The upper surface 305 of the frustum of a square pyramid, which is the tapered portion which widens towards the bottom, is formed continuously with the upper surface 307 of the incident portion of the rectangular CPC, and the right side surface 304 of the frustum of a square pyramid is formed continuously with the right side surface 308 of the incident portion which is the rectangular CPC. The lower and left sides are similar. The upper surface 302 of the rectangular CPC is the incident surface of light from the light source, and the bottom surface 303 of the frustum of a square pyramid, which is the tapered portion which widens towards the bottom, is the exit surface. The virtual surface 306 is the bottom surface of the rectangular CPC and is also the incident surface of the frustum of a square pyramid.

[0035] Here, the angle of inclination β1 (which is the taper angle β1) is the angle between the horizontal plane containing the optical axis and the upper or lower surface 305 of the tapered portion, and the angle of β2 (which is the taper angle β2) is the angle between the vertical plane containing the optical axis and the left or right surface 304 of the tapered portion. β1=arctan{(H2-H1) / 2L1}, β2=arctan{(W2-W1) / 2L1)} This is the result (see Figures 4 and 5). For light reflected from the tapered surface, the closer the light is to the optical axis, the more the parallelism improves by approximately 2β1 in the height direction for each reflection on the upper and lower surfaces, and by approximately 2β2 in the width direction for each reflection on the left and right surfaces. In the present invention, it has been found that when the sum of the length L1 of the tapered section and the length L2 of the incident section, i.e., the total length L, is 1.5 times or more the length D of the diagonal of the exit surface, homogenization of light from the light source and reduction of the divergence angle can be achieved with a shorter length than conventional tapered light tunnels. However, it has also been found that even with conventional tapered light tunnels, homogenization of light from the light source and reduction of the divergence angle can be achieved when the length is 6 times or more the length D of the diagonal of the exit surface. Therefore, the advantage of this first invention is that even when the total length L is between 1.5 and 5 times the length D of the diagonal of the exit surface, homogenization of light from the light source and reduction of the divergence angle, which cannot be achieved in conventional examples, can be achieved.

[0036] In this first invention, a rectangular CPC is further formed as the incident portion, with the upper surface 306 of the truncated pyramid, which is the tapered portion, as its base, and its upper surface 302 becomes the incident surface of light from the light source. Light incident on the incident surface 302 at a large incident angle first hits the side surface 307 of the incident portion, as shown in Figure 6, and the angle it makes with the optical axis rapidly decreases as it proceeds to the tapered portion. At any position on the upper side surface 307 of the incident portion, the angle β3 that the tangent makes with the optical axis is greater than the taper angle β1 of the tapered portion. This relationship also holds true for the lower, left, and right sides of the incident portion, where the angle that the tangent plane at a certain position makes with the horizontal or vertical plane containing the optical axis is greater than the corresponding taper angle of the tapered portion.

[0037] Figure 7 shows how light incident on the light guide optical component of the present invention is repeatedly reflected at the incident and tapered sections before reaching the exit surface. Due to the presence of the incident section, which consists of a rectangular CPC, the light incident on the incident surface 302 of the incident section is homogenized in a shorter length than conventional tapered light tunnels consisting only of a truncated square pyramid before reaching the exit surface 303 of the tapered section.

[0038] Next, the second invention of this application has a solid tapered portion of length L2 which is a first frustum of a square pyramidal The second truncated square pyramid has four flat trapezoidal sides, and of these, the angle β5 made with the horizontal plane containing the optical axis at any position on the upper and lower trapezoidal sides is greater than the taper angle β1, and of the four sides, the angle β6 made with the vertical plane containing the optical axis at any position on the left and right trapezoidal sides is greater than the taper angle β2, and furthermore, the sum of the length L1 of the tapered portion and the length L2 of the second truncated square pyramid (total length L) is 2.4 times or more and 5 times or less the length D of the diagonal of the exit surface of the tapered portion of the first truncated square pyramid. As will be explained in detail later, the length L2 of the second truncated square 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] In other words, in this second invention, a second truncated square pyramid with taper angles β5 and β6 and length L2 is formed in succession to a first truncated square pyramid with taper angles β1 and β2 and length L1, such that β5 > β1 and β6 > β2, and the relationship between the length D of the diagonal of the incident plane and the total length L is 2.4D ≤ L (= L1 + L2) ≤ 5D. Furthermore, the relationship between the incident portion length L2 and the tapered portion length L1 is 5.8% L1 ≤ L2 ≤ 19.6% L1, and in this case, the range is 1.1° ≤ β1 ≤ 3.3° and 3.3° ≤ β2 ≤ 6.4°.

[0040] In this second invention, the optical guide component has a second truncated square pyramid, which is the incident portion, formed continuously with the first truncated square pyramid, which is the tapered portion. Therefore, the four trapezoidal sides of the second truncated square pyramid are formed continuously with the four trapezoidal sides of the first truncated square pyramid. Of the four sides of the second truncated square pyramid, the taper angle β5 formed by the upper and lower two sides with the optical axis is greater than the taper angle β1 formed by the upper and lower two sides with the optical axis of the first truncated square pyramid, and the taper angle β6 formed by the left and right two sides with the optical axis of the second truncated square pyramid is greater than the taper angle β2 formed by the left and right two sides with the optical axis of the first truncated square pyramid.

[0041] In such a light-guiding optical component, light incident on the top surface of the second truncated square pyramid, which is square or rectangular with height H3 and width W3, is reflected off the side surface of the second truncated square pyramid, changes direction, reaches the bottom surface of the second truncated square pyramid, which is height H1 and width W1, and then continues to be incident on the tapered portion of the first truncated square pyramid, which widens towards the bottom. After repeated reflections off the side surface, it reaches the rectangular exit surface with height H2 and width W2, and exits from the exit surface.

[0042] In other words, in the light-guiding optical component of this second invention, light incident on the upper surface of the second truncated square pyramid is reflected by the top, bottom, left, and right sides of the second truncated square pyramid according to the inclination angle β5 or β6, significantly changing its direction of propagation, approaching the optical axis, and traveling toward the exit surface, which is the bottom surface. Then, it is incident on the tapered portion, which is the first truncated square pyramid, and changes its direction of propagation according to the taper angle β1 in the height direction and the taper angle β2 in the width direction relative to the optical axis, and travels closer to the optical axis.

[0043] This is due to the effect that, as mentioned before, of the four sides of the second truncated square pyramid, the angle β5 that makes contact with the optical axis at any position on the upper and lower sides is greater than β1, and of the four sides, the angle β6 that makes contact with the optical axis at any position on the left and right sides is greater than the angle β2 of the tapered portion. Due to the presence of this second truncated square pyramid, the light incident on the incident surface of the second truncated square pyramid is homogenized in a shorter length than a conventional optical component consisting of a tapered light tunnel made up of only the first truncated square pyramid, and reaches the exit surface of the first truncated square pyramid.

[0044] In this second invention, the sum of the length L1 of the tapered portion of the first truncated square pyramid and the length L2 of the second truncated square pyramid (total length L) must be between 2.4 and 5 times the length D of the diagonal of the emission surface. Below 2.4 times, no conditions were found to improve the homogeneity of the emitted light. When it exceeds 5 times and exceeds 6 times, even in conventional tapered light tunnels, a luminous beam with a nearly uniform and small divergence angle can be produced at the emission surface, but in tapered light tunnels with a length of 5 times or less, a luminous beam with a uniform and small divergence angle could not be produced.

[0045] In this second invention, when homogenization of the emitted light and 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. At that time, the inclination angle β1 of the tapered portion, which is the first truncated square 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 both have a first truncated square pyramid which is a tapered portion with taper angles β1 and β2, but the shape of the incident portion which is formed continuously with the tapered portion differs. In the first invention, as shown in the unfolded view in Figure 8, the side surface of the rectangular CPC of the incident portion is an internally reflective composite paraboloid, while in the second invention, as shown in the unfolded view in Figure 9, it is a simple truncated square pyramid. Furthermore, in both the first and second inventions, the inclination angle at each position of the incident portion is the same in that it is greater than the taper angle of the corresponding first truncated square pyramid.

[0047] Next, the third invention of this application is a light-guiding optical component characterized in that it has a tapered portion of length L1, which is a solid frustum of a square pyramid that widens in the direction of light propagation with a taper angle β7 in the height direction and a taper angle β8 in the width direction relative to the optical axis, extending 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 an incident portion of length L2, which is an elliptical frustum with the rectangle of height a1 and width b1 as its base and an ellipse of minor axis a3 and major axis b3 as its top surface, is formed continuously with the tapered portion, and at any position of the elliptical frustum, the angle β9 made between the inclined surface and the optical axis is greater than the taper angles β7 and β8, and the sum of the length L1 of the tapered portion and the length L2 of the elliptical frustum that is the incident portion (total length L) is 2 times or more and 5 times or less the length D of the diagonal of the exit surface. In such light-guiding optical components, both uniformity of light at the emission surface and narrowing of the emission angle are achieved.

[0048] Furthermore, when both the homogeneity of light and the narrowing of the angle are achieved at the exit surface, the length L2 of the frustum ellipsoid 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 this third invention and the first and second inventions is that the incident portion is an elliptical frustum of length L2, rather than a square frustum of length L2 (see Figures 10 and 13). Figure 13 shows only the incident portion of the elliptical frustum.

[0050] The taper angle β7 formed by the upper and lower surfaces of the tapered section and the optical axis, and the taper angle β8 formed by the left and right surfaces and the optical axis, β7=arctan{(H2-a1) / 2L1}, β8=arctan{(W2-b1) / 2L1)} This is the result (see Figures 11 and 12). For each reflection of a light ray reflected by a tapered surface, the parallelism of light traveling in a direction nearly perpendicular to the optical axis improves by approximately 2β7 in the height direction, and the parallelism of light traveling in a direction nearly horizontal to the optical axis improves by approximately 2β8 in the width direction.

[0051] In Figure 10, the base 303 of the flared truncated square pyramid is a rectangular emission surface. In the present invention, a series of tapered elliptical truncated pyramids are formed with the top surface of the truncated square pyramid as the base, and the top surface of the elliptical truncated pyramid becomes the incident surface of light 302.

[0052] Light incident at a large angle of incidence on the incident surface 302 of the frustum ellipse strikes the inner surface of the frustum ellipse (angle β9), which has a greater inclination than the inclination angles β7 and β8 of the tapered section, and is reflected, significantly reducing the angle with respect to the optical axis. After entering the tapered section, the angle with respect to the optical axis decreases by approximately 2β7 or 2β8 with each reflection, improving homogeneity as it reaches the exit surface 303. The length L1 of the tapered section can be made considerably shorter than the length of a conventional tapered light tunnel. Specifically, the sum of the length L1 of the tapered section and the length L2 of the frustum ellipse (total length L) can be between 2 and 5 times the diagonal length D of the exit surface.

[0053] In the behavior of light rays inside the optical guide component of the present invention shown in Figures 3 and 10, the incident light contains a mixture of light rays with a large angle to the optical axis and light rays with a small angle to the optical axis. By selectively reflecting only the light rays with a large angle of incidence at the side of the incident section, the angle of the reflected light rays with the optical axis is significantly reduced. On the other hand, light rays with a small angle to the optical axis at the stage of incidence do not get reflected at the side of the incident section and are only reflected at the side of the tapered section, so the number of reflections does not decrease. As a result, the uniformity of the light distribution at the exit surface is not significantly reduced, and the angle of the light rays emitted from the exit surface can be narrowed.

[0054] Furthermore, by adopting a double taper structure that combines two shapes—an inlet section and a tapered section—the design flexibility is increased compared to the simple truncated pyramidal tapered light tunnel shown in Figure 2. This allows for independent adjustment of the shapes of the inlet section and the tapered section, contributing to the homogenization of the light distribution at the exit surface.

[0055] As a result of these factors, in this third invention, it becomes possible to achieve both homogenization of light distribution at the emission surface and narrowing of the divergence angle of emitted light in a short light-guiding optical component whose total length L is between 2 and 5 times the diagonal length D of the emission surface.

[0056] Figure 14 shows that the side surface of the frustum ellipse is a paraboloid that bulges outward, and can also be said to be a modified example of the shape of the incident section in the third invention. Figure 13 is a simple frustum ellipse, but Figure 14 shows that the inclined surface of the frustum ellipse is either a paraboloid or a monocurved surface that bulges outward.

[0057] Next, the fourth invention of this application is a tapered portion of length L1, which is a frustoconical pyramid that widens at an angle β7 in the height direction and an angle β8 in the width direction with respect to the optical axis, extending from a rectangular incident surface of height a1 and width b1 toward a rectangular exit surface of height H2 and width W2, and an incident portion of length L2 is continuously formed on the tapered portion of length L2, which is a frustoconical pyramid that widens at an angle β7 in the height direction and an angle β8 in the width direction with respect to the optical axis, with the rectangle of height a1 and width b1 as the base, the top surface being a circle with a diameter a3, and the side surface being a circular CPC which is an internally reflective parabolic surface, and at any position on the side surface of the incident portion, the angle β that the tangent plane makes with the optical axis 10 This is a light guide optical component characterized by being larger than β7 and β8, and the sum of the length L1 of the tapered portion and the length L2 of the circular CPC which is the incident portion (total length L) being in the range of 2.4 times or more and 5 times or less the length D of the diagonal of the exit surface.

[0058] In other words, the incident portion of the fourth invention is a frustoconical shape as shown in Figure 15, where the top surface of the incident portion is not elliptical but circular with diameter a3, the bottom surface of the incident portion is rectangular a1xb1, and the side surface of the incident portion is an internally reflective composite paraboloid (this shape of the incident portion is called a circular CPC). The tapered portion, like the third invention, consists of a frustoconical pyramid that widens at an angle β7 in the height direction and an angle β8 in the width direction with respect to the optical axis, from a rectangular incident surface with height a1 and width b1 to a rectangular exit surface with height H2 and width W2. The length of the incident portion is L2, and the angle of inclination β of the tangent plane with respect to the optical axis is at any position on the side surface of the incident portion of the circular CPC. 10 The angles β7 and β8 that the tapered portion, which is a flared truncated square pyramid, makes with the optical axis are greater than these angles.

[0059] In the fourth invention, when the sum of the length L1 of the tapered portion and the length L2 of the circular CPC which is the incident portion (total length L) is in the range of 2.4 times or more and 5 times or less of the length D of the diagonal of the exit surface, the uniformity of light on the exit surface is excellent and the divergence angle is also small. At this time, 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, and 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 incident surface of the incident section, is reflected by the parabolic surface, travels in a direction approaching the optical axis, and enters the tapered section. In the tapered section, one reflection from the upper and lower surfaces brings the light closer to the optical axis by approximately 2β7° each time, depending on the angle and direction of incidence, and one reflection from the left and right surfaces brings it closer to the optical axis by approximately 2β8° each time, again depending on the angle and direction of incidence, improving homogeneity as it travels towards the exit surface and exits from the exit surface.

[0061] In addition, in the first to fourth inventions of this application, when the exit surface or incident surface is described as rectangular, it is not necessary for the four corners to be right angles in a strict sense; the corners may be rounded to prevent damage from contact.

[0062] In the first to fourth inventions, a condensing lens or a diverging lens can be integrated at the exit surface of the light guide optical component, as shown in Figure 16, to create a light guide optical component that has a condensing or diverging function. The condensing or diverging lens used here is usually a convex or concave lens with a curvature on one side, which is substantially flat and integrated with the exit surface, and on the opposite side. This eliminates the loss due to divergence of light components with a large divergence angle at the exit surface, allowing light to be projected forward from the condensing lens, and if a diverging lens is used, the irradiation area can be increased.

[0063] The fifth invention of this application is a light guide optical component formed by arranging and integrating multiple light guide optical components disclosed in the first to fourth inventions of this application. Multiple may be two, or they may be arranged in an M-row and N-column configuration, for example. When described as M-row and N-column, at least one of M or N is 2 or more. When forming a lighting device, the number and configuration are equal to the number of LED elements, and the incident surface of the incident portion of each light guide optical component is positioned opposite the LED elements. For example, if there are 2 rows and 3 columns of LED elements, the light guide optical component is also arranged in 2 rows and 3 columns and integrated, resulting in a lighting device in which the incident surface of the incident portion of each light guide optical component is in contact with each LED element. In the case of an M-row and N-column configuration, for ease of handling, to prevent damage due to contact, or for ease of manufacturing, it is conceivable that light guide optical components may not be placed in the four corners, or that a part of the central section may be omitted. Even in these cases, no major problems occur in the uniformity of the illuminance of the illuminated surface. Furthermore, in these fifth inventions as well, a focusing lens or a diverging lens may be integrated at the position of the emission surface, as shown in Figure 16.

[0064] Figures 17 and 18 illustrate a five-row, five-column light guide optical component, which is one embodiment of the fifth invention. Figure 17 is an overall perspective view from the light emission side, and Figure 18 is a front view from the light incidence side. In this embodiment, a focusing lens is integrated into the emission surface of each light guide optical component. In this embodiment, the configuration is five rows and five columns, and the size of the emission surface is similar to the shape of the light bulb, which is a display element.

[0065] The sixth invention of this application is an illumination device in which an LED element is placed in contact with the incident surface of the incident portion of the light guide optical component described in the first to fifth inventions of this application. For example, it is an illumination device in which an LED element is placed in contact with the incident surface 302 in Figure 3 or the incident surface 302 in Figure 10. Regardless of which light guide optical component is used, an illumination device with a uniform illuminance distribution on the output surface can be obtained.

[0066] The seventh invention of this application is a projection-type display device that focuses the light beam from the output surface of the illumination device according to the sixth invention onto a light bulb, which is a display element, using a focusing lens system, and irradiates it, and then magnifies the image generated by the display element using an enlargement projection optical system and projects it onto a screen.

[0067] Figure 19 shows an example of the configuration of a projection-type display device. Examples of light bulbs for projection-type display devices include transmissive liquid crystal display panels, reflective liquid crystal display panels, or DMDs (digital micromirror devices). However, according to the present invention, parallel light with uniform illuminance can be obtained, which is particularly effective for DMD display elements that are spaced apart from the light source and light guide optical components.

[0068] Since the plan is to illuminate a display element such as a liquid crystal display element or DMD used in a projector with uniform intensity by projecting the real image from the emission surface 303, it is desirable that the ratio of the width to the height of the emission surface 303 is similar to that of the display element. The ratio of the width W to the height H of these display elements is usually 16:9 or 4:3. [Effects of the Invention]

[0069] According to the light guide optical component of the present invention, by separately controlling the parameters of the incident section and the tapered section, the inclination angle at each side of the incident section is made larger than the taper angle of the tapered section, for a total length shorter than that of a conventional tapered light tunnel. This allows light from the light source to reach the output surface of the light guide optical component as homogeneous light with a small divergence angle, in a shorter length than was possible in conventional examples. Furthermore, when the ratio of the sum of the length L1 of the tapered section and the length L2 of the incident section (total length L) to the length D of the diagonal of the output surface is set to the range of 1.5 to 5 when the incident section is a rectangular CPC, 2.4 to 5 when the incident section is a second truncated square pyramid, 2 to 5 when the incident section is an elliptical truncated pyramid, and 2.4 to 5 when the incident section is a circular CPC, homogeneous output light with a small divergence angle can be obtained. In addition, by arranging and integrating multiple light guide optical components, a light guide optical component with a large area can be made.

[0070] According to the present invention, a lighting device using the light guide optical component and LED light-emitting element can be obtained, which has a uniform illuminance distribution and a small divergence angle. Furthermore, by arranging and integrating multiple light guide optical components into a single light guide optical component and an LED light-emitting element, a lighting device that emits light over a wide surface can be obtained.

[0071] According to the projection-type display element using the illumination device of the present invention, the light bulb is illuminated with illumination of extremely uniform illuminance and a narrow divergence angle, so that a projection image with excellent illuminance distribution can be projected onto the screen. According to the illumination device of the present invention, parallel light with a small divergence angle can be irradiated with a uniform illuminance distribution, so it is suitable for use in projection-type display devices using a DMD with a wide distance between the illumination device and the light bulb. [Brief explanation of the drawing]

[0072] [Figure 1] This diagram shows the reflection of light in a rectangular prism-shaped light tunnel. [Figure 2] This figure shows the reflection of light in a tapered lite tunnel that widens towards the bottom, forming a truncated square pyramid. [Figure 3] This is a perspective view showing an example of the configuration of a light guide optical component according to the first invention of this application. [Figure 4] This is a side view of an example of the configuration of a light guide optical component according to the first invention of this application. [Figure 5] This is a plan view of an example of the configuration of a light guide optical component according to the first invention of this application. [Figure 6] This figure shows the path of light incident on the incident portion of the first invention of this application. [Figure 7] This figure shows the process by which light incident on the incident surface is emitted from the exit surface in the first invention of this application. [Figure 8] This figure shows the rectangular CPC, which is the incident portion of the light guide optical component of the first invention of this application. [Figure 9] This figure shows a truncated square pyramid, which is the incident portion of the light guide optical component of the second invention of this application. [Figure 10] This is a perspective view showing an example of the configuration of a light guide optical component according to the third invention of this application. [Figure 11] This is a side view of an example of the configuration of a light guide optical component according to the third invention of this application. [Figure 12] This is a plan view of an example of the configuration of a light guide optical component according to the third invention of this application. [Figure 13] This figure shows the frustum of the elliptic, which is the incident portion of the optical guide component of the third invention of this application. [Figure 14] This figure shows another embodiment of an elliptical frustum, which is an example of the incident portion of the optical guide component of the third invention of this application. [Figure 15] This figure shows a circular CPC, which is an example of the incident portion of the optical guide component of the fourth invention of this application. [Figure 16] This figure shows an example of a light-guiding optical component in which a focusing lens is integrated into the output surface, which is an example of the first invention of this application. [Figure 17] This is a perspective view showing an example of a light-guiding optical component in which multiple light-guiding optical components, which are the first invention of this application, are arranged and integrated. [Figure 18] This is a plan view showing an example of a light-guiding optical component in which multiple light-guiding optical components, which are the first invention of this application, are arranged and integrated. [Figure 19] This figure shows an example of the configuration of the seventh invention of this application, a projection-type display device, using an example of the sixth invention of this application, a lighting device. [Figure 20] This figure shows the angle β3 that a tangent plane at any position on the upper or lower surface of a rectangular CPC makes with a horizontal plane containing the optical axis, according to the first invention of this application. [Figure 21] This figure shows an example of a ray tracing simulation result for a light ray incident on a light guide optical component of the first invention. [Figure 22] This figure shows an example of the illuminance distribution in the X direction (width direction) at the exit surface of a light ray incident on the light guide optical component of the first invention. [Figure 23] This figure shows an example of the illuminance distribution in the Y direction (height direction) at the exit surface of a light ray incident on the first optical component of the present invention. [Figure 24]This figure shows an example of the divergence angle distribution in the X direction (width direction) and Y direction (height direction) at the exit surface of a light ray incident on the light guide optical component of the first invention. [Figure 25] This figure shows another example of the results of a ray tracing simulation of a light ray incident on the optical guide component of the first invention. [Figure 26] This figure shows another example of the illuminance distribution in the X direction (width direction) at the exit surface of a light ray incident on the light guide optical component of the first invention. [Figure 27] This figure shows another example of the illuminance distribution in the Y direction (height direction) at the exit surface of a light ray incident on the light guide optical component of the first invention. [Figure 28] This figure shows another example of the divergence angle distribution in the X and Y directions at the exit surface of a light ray incident on the light guide optical component of the first invention. [Figure 29] This is an example of a ray tracing simulation result for a light ray incident on a tapered lite tunnel, which is a comparative example. [Figure 30] This is an example showing the illuminance distribution in the X direction at the exit surface of a light ray incident on a tapered light tunnel, which is a comparative example. [Figure 31] This is an example showing the illuminance distribution in the Y direction at the exit surface of a light ray incident on a tapered light tunnel, which is a comparative example. [Figure 32] This figure shows an example of a ray tracing simulation result for a light ray incident on a light guide optical component of the second invention. [Figure 33] This figure shows an example of the illuminance distribution in the X direction (width direction) at the exit surface of a light ray incident on the light guide optical component of the second invention. [Figure 34] The second figure shows an example of the illuminance distribution in the Y direction (height direction) at the exit surface of a light ray incident on the light guide optical component of the present invention. [Figure 35] This figure shows an example of the divergence angle distribution in the X direction (width direction) and Y direction (height direction) at the exit surface of a light ray incident on the light guide optical component of the second invention. [Figure 36] This figure shows another example of the results of a ray tracing simulation of a light ray incident on a light guide optical component of the second invention. [Figure 37] This figure shows another example of the illuminance distribution in the X direction (width direction) at the exit surface of a light ray incident on the light guide optical component of the second invention. [Figure 38] This figure shows another example of the illuminance distribution in the Y direction (height direction) at the exit surface of a light ray incident on the light guide optical component of the second invention. [Figure 39] This figure shows another example of the divergence angle distribution in the X and Y directions at the exit surface of a light ray incident on the light guide optical component of the second invention. [Figure 40] This figure shows an example of a ray tracing simulation result for a light ray incident on a light guide optical component of the third invention. [Figure 41] This figure shows an example of the illuminance distribution in the X direction (width direction) at the exit surface of a light ray incident on the light guide optical component of the third invention. [Figure 42] This figure shows an example of the illuminance distribution in the Y direction (height direction) at the exit surface of the light ray incident on the third optical component of the present invention. [Figure 43] This figure shows an example of the divergence angle distribution in the X direction (width direction) and Y direction (height direction) at the exit surface of a light ray incident on the light guide optical component of the third invention. [Figure 44] This figure shows another example of the results of a ray tracing simulation of a light ray incident on a light guide optical component of the third invention. [Figure 45] This figure shows another example of the illuminance distribution in the X direction (width direction) at the exit surface of a light ray incident on the light guide optical component of the third invention. [Figure 46] This figure shows another example of the illuminance distribution in the Y direction (height direction) at the exit surface of a light ray incident on the light guide optical component of the third invention. [Figure 47] This figure shows another example of the divergence angle distribution in the X and Y directions at the exit surface of a light ray incident on the light guide optical component of the third invention. [Figure 48] This figure shows the angle β10 that the tangent plane at any position on the circular CPC, which is the incident portion, makes with the optical axis in the fourth invention. [Figure 49]This figure shows an example of a ray tracing simulation result for a light ray incident on a light guide optical component of the fourth invention. [Figure 50] This figure shows an example of the illuminance distribution in the X direction (width direction) at the exit surface of a light ray incident on the light guide optical component of the fourth invention. [Figure 51] The fourth figure shows an example of the illuminance distribution in the Y direction (height direction) at the exit surface of the light ray incident on the light guide optical component of the present invention. [Figure 52] This figure shows an example of the divergence angle distribution in the X direction (width direction) and Y direction (height direction) at the exit surface of a light ray incident on the light guide optical component of the fourth invention. [Figure 53] This figure shows another example of the results of a ray tracing simulation of a light ray incident on the optical guide component of the fourth invention. [Figure 54] This figure shows another example of the illuminance distribution in the X direction (width direction) at the exit surface of a light ray incident on the light guide optical component of the fourth invention. [Figure 55] This figure shows another example of the illuminance distribution in the Y direction (height direction) at the exit surface of a light ray incident on the light guide optical component of the fourth invention. [Figure 56] This figure shows another example of the divergence angle distribution in the X and Y directions at the exit surface of a light ray incident on the optical guide component of the fourth invention. [Figure 57] This figure shows the illuminance distribution in the X direction (width direction) when the total length L is only 1.2 times the diagonal angle D of the emission surface in the light guide optical component according to the first invention (Example 51). [Figure 58] This figure shows the illuminance distribution in the Y direction (height direction) in the light guide optical component according to the first invention, when the total length L is only 1.2 times the diagonal angle D of the emission surface (Example 51). [Figure 59] This figure shows the illuminance distribution in the X direction (width direction) when the total length L is only 1.8 times the diagonal angle D of the emission surface in the light-guiding optical component according to the third invention (Example 52). [Figure 60] This figure shows the illuminance distribution in the Y direction (width direction) when the total length L is only 1.8 times the diagonal angle D of the emission surface in the light guide optical component according to the third invention (Example 52). [Figure 61] This figure shows the illuminance distribution in the X direction (width direction) in the light guide optical component according to the second invention, when the total length L is 2.4 times the diagonal angle D of the emission surface (Example 54). [Figure 62] This figure shows the illuminance distribution in the Y direction (width direction) in the light guide optical component according to the second invention, when the total length L is 2.4 times the diagonal angle D of the emission surface (Example 54). [Figure 63] This figure shows the illuminance distribution in the X direction (width direction) in the light guide optical component according to the fourth invention, when the total length L is 2.4 times the diagonal angle D of the emission surface (Example 55). [Figure 64] This figure shows the illuminance distribution in the Y direction (width direction) in the light guide optical component according to the fourth invention, when the total length L is 2.4 times the diagonal angle D of the emission surface (Example 55). [Figure 65] This figure shows the results of a ray tracing simulation for a light ray incident on an optical guide component that integrates multiple optical guide components (5 rows and 5 columns), which is the sixth invention. [Figure 66] This figure shows the illuminance distribution in the X direction of a light ray incident on a light guide optical component, which is the sixth invention, and integrates multiple light guide optical components (5 rows and 5 columns). [Figure 67] This figure shows the illuminance distribution in the Y direction of a light ray incident on a light guide optical component, which is the sixth invention, and integrates multiple light guide optical components (5 rows and 5 columns). [Figure 68] This figure shows the change in the illuminance distribution in the X direction when the taper angle is increased, using Example 2 as the standard. [Figure 69] This figure shows the change in the illuminance distribution in the X direction when the taper angle is reduced, using Example 2 as the standard. [Modes for carrying out the invention]

[0073] The following shows the simulation results for embodiments and comparative examples of the first to fourth inventions of this application, and the obtained data is summarized in a table. Some results are presented as they were obtained. [Examples]

[0074] Regarding the first invention of this application, as a means of illuminating a display element (light bulb) in a projector, as shown in Figure 19, an illumination device is configured using a scattering light source 701 consisting of an LED element and a light guide optical component 301 of the first invention of this application, and a projection display device using the illumination device is configured.

[0075] In subsequent simulations, an LED element with a wavelength of 550 nm, an emitting surface diameter of 0.255 mm, and an 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 guide optical component and tapered light tunnel of the present invention was set to 1.5185. Here, glass was selected as the material for the light guide optical component, but it is not limited to glass; resin may also be used. FWHM refers to the full width at half maximum of the luminance distribution of the LED element.

[0076] In the optical system shown in Figure 19, the ray trajectories were simulated to show how the incident light rays propagate to the exit surface 303 and exit, in two cases: when using the first invention's light guide optical component 301, which consists of a tapered section and an incident section that is a rectangular CPC as shown in Figure 3, and when using the existing truncated square pyramidal tapered light tunnel shown in Figure 2 (these were obtained using the ray tracing simulation software Ansys Zemax). The results are summarized in Table 1. FWHM in Table 1 is the full width at half maximum of the divergence angle of the LED light that has passed through the light guide optical component obtained from the ray tracing simulation. For the homogeneity of the exit light, ◎ indicates a flat illuminance distribution with excellent homogeneity, ○ indicates a good illuminance distribution with a variation of less than 5%, △ indicates a variation of 5% to 10%, and × indicates a variation of 10% or more.

[0077] [Table 1]

[0078] All the examples in Table 1 relate to the light guide optical component of the first invention, and all the comparative examples relate to the conventional tapered light tunnel. The size of the exit surface is standardized to 2.22 mm x 1.25 mm. Ray tracing simulations were performed by varying the length of the incident section from 0.4 mm to 0.7 mm, and setting the size of the incident surface that receives light to three types: 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 the total length L of the light guide optical component when it was 1.5 times, 2 times, 3 times, 4 times, and 5 times the diagonal length D of the exit surface. On the other hand, for the comparative example, the tapered light tunnel, the overall length was set to match the light-guiding optical component of the first invention, with the longest length being up to 6 times the diagonal length D of the exit surface. Three types of incident surface sizes were used: 0.3 mm x 0.3 mm, 0.7 mm x 0.4 mm, and 1.1 mm x 0.6 mm. Ray tracing simulations were performed for a shape that uniformly widens in a tapered manner from the incident surface to the exit surface at angles β1 between the upper and lower surfaces and the horizontal plane containing the optical axis, and angles β2 between the left and right surfaces and the vertical plane containing the optical axis.

[0079] Table 2 summarizes the shape model parameters for the optical guide component of the first invention used in the ray tracing simulation. In addition to the total length L, tapered section length L1, incident section length L2, incident surface size H3xW3, and exit surface size H2xW2, the taper angle β1, which is the angle that the upper and lower surfaces of the tapered section make with the horizontal direction, and the taper angle β2, which is the angle that the left and right surfaces make with the vertical direction, are also listed. In this [Example 1], the incident section of the rectangular CPC-shaped truncated pyramid has an angle of β3 (see Figure 20) at which the tangent plane at either the upper or lower surface makes with the horizontal plane containing the optical axis, and an angle of β4 at which the tangent plane at either the left or right surface makes with the vertical plane containing the optical axis. The relationship between the horizontal taper angles β1 and β3 is β3 > β1, and the relationship between the vertical taper angles β2 and β4 is β4 > β2.

[0080] [Table 2]

[0081] For example, in Example 2 of [Example 1], the total length L of the optical guide component is 5.1 mm, which is twice the diagonal D of the exit surface aperture, of which 0.5 mm is the length L2 of the incident section and 4.6 mm is the length L1 of the tapered section. The exit surface is 2.22 mm x 1.25 mm. The incident surface size of the incident section is 0.3 mm x 0.3 mm. The taper angle β1, which is the angle that the upper and lower surfaces of the tapered section make with the horizontal plane containing the optical axis, is 4.3°, and the taper angle β2, which is the angle that the side surface in the width direction makes with the vertical plane containing the optical axis, is 10.0°. In contrast, the minimum angle of inclination of the upper and lower surfaces of the incident section is 5.2° and the maximum angle is 29.2°, and the minimum angle of inclination of the left and right surfaces is 10.1° and the maximum angle is 30.3°, all of which are larger angles than the corresponding taper angles of the tapered section.

[0082] Similarly, Table 3 summarizes the shape model parameters for conventional tapered light tunnels in which ray tracing simulations were performed. In addition to the ratio of the total length L to the length D of the diagonal of the exit surface, the total length L, the size of the incident surface, and the size of the exit surface, the taper angles β1 of the upper and lower surfaces and β2 of the left and right surfaces are also listed.

[0083] [Table 3]

[0084] Among the examples shown in Table 1, five out of the nine examples conducted (Examples 2, 5, 7, 8, and 9) exhibited extremely excellent homogeneity of emitted light (rated as ◎ in the table). Three examples (Examples 1, 3, and 6) had homogeneity variations of 5% or less (rated as ○ in the table), while only Example 4 had a homogeneity variation of 5% or more (rated as △ in the table). On the other hand, in the conventional tapered light tunnels, simulations were performed on 18 examples listed as comparative examples. However, only examples with a length six times the diagonal of the emitted surface (Comparative Examples 16, 17, and 18) showed excellent illuminance distribution homogeneity, and among these, Comparative Example 18 had a large divergence angle. In the other comparative examples, Comparative Examples 9 and 12 showed fair illuminance distribution homogeneity (variability within 5%), but both examples had large divergence angles of ±25° or more. Other comparative examples had illuminance distribution variations of at least 5% or even greater.

[0085] Figure 21 shows the results of a ray tracing simulation for Example 2 in Table 1. The left side of Figure 21 shows the ray trajectory within the optical guide component, where the ray beam appears dense. In the center is the exit surface of the tapered section (indicated by a rectangle), and to the right of the exit surface of the tapered section is outside the optical guide component, where the rays diverge from the exit surface and appear sparse. Figures 22 and 23 show the illuminance distribution in the X and Y directions on the exit surface obtained from the ray beam at the position of the tapered section exit surface in Figure 21. Furthermore, Figure 24 shows the radiance distribution in angular space. The radiance distribution in angular space refers to the luminance that appears distributed in angular space when the optical guide 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 line represents the divergence angle distribution in the Y direction. In both the X and Y directions, the shape of the light guide optical component of this first invention exhibits far superior uniformity of illuminance distribution compared to the truncated pyramidal tapered light tunnel, which will be shown later as a comparative example. Furthermore, the angular distribution of radiance shows that when using the light guide optical component of the present invention, the divergence angle in the X direction (FWHM: full width at half maximum) is kept within a narrow range of ±13.35°, and the divergence angle in the Y direction (FWHM: full width at half maximum) is kept within a narrow range of ±16.97°.

[0086] Regarding the results of the embodiments of the first invention, in Embodiment 1, where the total length L was only 1.5 times the diagonal of the emission plane D, the divergence angle of the emitted light was kept within a low range, and the illuminance distribution in the Y direction was uniform, but the illuminance distribution in the X direction fluctuated within a range of about 3%. With this level of illuminance distribution, the homogeneity evaluation was considered "good". In the case where the total length L was twice D, even in Embodiment 3, where the incident length and incident surface size were larger than in Embodiment 2, fluctuations of about 3% were observed in the illuminance distribution in the X direction, and in Embodiment 4, a drop in illuminance of nearly 10% was observed in the central part of the illuminance distribution in the X direction. Therefore, in the case where the total length was twice the diagonal of the emission plane, only Embodiments 2 and 3 showed good results in all aspects: illuminance distribution in the X direction, illuminance distribution in the Y direction, and divergence angle.

[0087] As another example showing good results, the ray tracing simulation results (Figure 25), illuminance distribution in the X direction (Figure 26), illuminance distribution in the Y direction (Figure 27), and divergence angle distribution (Figure 28) for Example 7 in Table 1 are shown. Excellent homogeneity of illuminance distribution is observed in both the X and Y directions. Furthermore, it was found that narrowing of the radiance divergence angle was achieved, with a FWHM (full width at half maximum) of ±9.69° in the X direction and an FWHM of ±15.35° in the Y direction (height direction). The left side of Figure 25 shows the ray trajectory within the optical guide component, where the ray beam appears dense. A rectangle is visible in the center indicating the exit surface of the tapered section, and the area to the right of the exit surface of the tapered section is outside the optical guide component, where the rays diverge from the exit surface and appear sparse. In Figure 28, the solid line shows the divergence angle in the X direction, and the dashed line shows the divergence angle in the Y direction.

[0088] From the results of the embodiments of the first invention described above, and also referring to the results of the comparative examples, it was found that when the total length L is 1.5 times or more and 5 times or less the length D of the diagonal of the emission surface, homogeneity of the illuminance distribution and narrowing of the angle can be stably and reproducibly achieved. Furthermore, from the results shown in Tables 1 and 2, it was found that when the ratio L2 / L1 of the length of the incident section to the length of the tapered section is between 2.4% and 13.4%, homogeneity of the illuminance distribution and narrowing of the angle can be achieved. In addition, it was found that the taper angle β1 in the tapered section 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 on Comparative Example 4 in Table 1, one of the conventional tapered light tunnels (Figure 29), and the illuminance distribution in the X direction (Figure 30) and the illuminance distribution in the Y direction (Figure 31) were obtained. Although there were no problems with the illuminance distribution in the Y direction, the illuminance distribution in the X direction showed large dips of more than 10% in two locations, indicating that the illuminance distribution was not homogeneous. The divergence angle was at a level that was almost problem-free.

[0090] Other results are summarized in Table 1. As mentioned above, samples with excellent homogeneity in the X-direction illuminance distribution and Y-direction illuminance distribution, similar to Examples 2 and 7, were rated ◎; samples with homogeneity variation of 5% or less were rated ○; samples with homogeneity variation between 5% and 10% were rated △; and samples with homogeneity problems (variation of 10% or more), similar to Comparative Example 4, were rated ×. Regarding the divergence angle, those within ±15° were considered to have achieved angle narrowing, those within ±20° were considered to be within the acceptable range, and those exceeding ±20° were considered to have not achieved sufficient angle narrowing.

[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, with a length six times the diagonal of the exit plane and incident surface sizes of 0.3 x 0.3 mm and 0.7 x 0.4 mm, were able to achieve both illuminance distribution homogeneity and angle narrowing. In Comparative Example 15, with a length five times the diagonal of the exit plane and an incident surface of 1.1 x 0.6 mm, illuminance distribution homogeneity was achieved, but the divergence angle reached nearly ±30°, and angle narrowing was not achieved. The same can be said for Comparative Examples 9 and 12. In other words, it was found that in conventional tapered light tunnels, both illuminance distribution homogeneity and angle narrowing cannot be achieved unless the total length L is six times the length D of the diagonal of the exit plane. Conversely, it was found that both illuminance distribution homogeneity and angle narrowing cannot be achieved if the total length L is five times or less the length D of the diagonal of the exit plane. [Examples]

[0092] Next, an embodiment relating to the light guide optical component of the second invention of this application is shown. [Embodiment 1] of the first invention concerned a light guide optical component in which a rectangular CPC-shaped incident portion, as shown in Figure 8, is continuously formed on the upper surface of a solid frustum of a square pyramid with taper angles β1 and β2. In this [Embodiment 2], simulation results are shown for a light guide optical component in which a general frustum of a square pyramid shape, as shown in Figure 9, is continuously formed on the upper surface of a solid first frustum of a square pyramid with taper angles β1 and β2. In this [Embodiment 2], the second frustum of a square pyramid, which is the incident portion, has taper angles β5 and β6, with β5 > β1 for the taper angles β1 and β5 in the vertical direction, and β6 > β2 for the taper angles β2 and β6 in the left and right direction.

[0093] Table 4 shows the parameters related to the shape of the optical guide component used in the simulation, and Table 5 shows the simulation results. The taper angle β1 of the upper and lower surfaces of the tapered section is in the range of 0.8° to 6.3°, and the taper angle β2 of the left and right surfaces is in the range of 3.3° to 13.1°. On the other hand, in the truncated square pyramid of the incident section, the taper angle β5 of the upper and lower surfaces is in the range of 10.7° to 18.7°, and the taper angle β6 of the left and right surfaces is in the range of 16.5° to 23.0°, all of which are larger than the taper angle of the tapered section. The size of the incident surface is 0.3mm x 0.3mm, 0.4mm x 0.4mm, or 0.7mm x 0.4mm, and the incident section length L2 is set to 0.4mm to 1.3mm depending on the total length L. The ratio of the incident section length L2 to the tapered section length L1 is in the range of 5.8% to 34.5%.

[0094] In cases where the total length L is 3, 4, and 5 times the length D of the diagonal of the emission surface, the homogeneity of the illuminance distribution on the emission surface is excellent, and the divergence angle is small. In the case where the total length L is 2 times the length D of the diagonal of the emission surface, the divergence angle is small, but there is a variation of about 5% in the homogeneity of the illuminance distribution on the emission surface. In the case where the total length L is 1.5 times the length D of the diagonal of the emission surface, the divergence angle is still small, but there is a variation of more than 5% in the homogeneity of the illuminance distribution on the emission surface. Therefore, from the results shown in Table 5, it was found that in [Example 2], in the case where the total length L is 2 times the diagonal of the emission surface (Examples 21, 22, and 23), the homogeneity of the illuminance distribution is insufficient, and when the total length L is 3 times the diagonal of the emission surface (Examples 25 and 26), both homogeneity of the illuminance distribution and narrowing of the divergence angle can be satisfied.

[0095] [Table 4]

[0096] [Table 5]

[0097] Two examples of ray tracing simulation results from this [Example 2] are presented. One is Example 27, where the total length L is 10.2 mm, which is four times the length D of the diagonal of the exit surface, and the length L2 of the incident part is 0.8 mm, with L2 / L1 = 8.5%. The ray trajectory is shown in Figure 32, the homogeneity in the X direction (width direction) at the exit surface is shown in Figure 33, the homogeneity 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, which is 1.5 times the length D of the diagonal of the exit surface, and the length L2 of the incident part is 0.4 mm, with L2 / L1 = 11.7%. The ray trajectory is shown in Figure 36, the homogeneity in the X direction at the exit surface is shown in Figure 37, the homogeneity 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 the ray trajectories, the left side shows the ray trajectories within the optical guide component, where the ray beam appears dense. In the center is the exit surface of the tapered section (indicated by a rectangle), and to the right of the exit surface of the tapered section is outside the optical guide component, where the rays diverge from the exit surface and appear sparse. In Figures 35 and 39, the dark solid line shows the divergence angle in the X direction, and the light solid line shows the divergence angle in the Y direction.

[0098] In Example 27 of Example 2, as shown in Figures 33 and 34, the illuminance distribution on the emission surface was excellent in homogeneity, and as shown in Figure 35, the divergence angle was within ±15°, indicating excellent straight-line propagation. On the other hand, in Example 21, as shown in Figure 39, although the divergence angle was not a problem, as shown in Figures 37 and 38, the illuminance distribution on the emission surface had a variation of more than 5% in both the X and Y directions, and the homogeneity was not satisfactory. Other results are shown in Table 5. In examples where the total length L was 3 times or more the length D of the diagonal of the emission surface, excellent homogeneity was shown, similar to Example 27, and the divergence angle was also small. On the other hand, in examples where the total length L was 2 times or less the length D of the diagonal of the emission surface, although the divergence angle was small, the homogeneity of the illuminance distribution on the emission surface was poor, similar to Example 21, with a variation of more than 5%. [Examples]

[0099] Next, an embodiment of the light guide optical component of the third invention of this application is shown. In [Embodiment 1] of the first invention and [Embodiment 2] of the second invention, the light guide optical component was formed by continuously forming a rectangular CPC-shaped incident portion or a general truncated square pyramidal incident portion on the upper surface of a solid truncated square pyramid with taper angles β1 and β2. However, in this [Embodiment 3], the simulation results are for a light guide optical component in which an elliptical truncated square pyramidal incident portion, as shown in Figure 13, is continuously formed on the upper surface of a solid truncated square pyramid with taper angles β7 and β8. In this [Embodiment 3], the elliptical truncated square pyramid, which is the incident portion, has an inclination angle of β9 at any position on the slope, and the relationship between β9 and the taper angles β7 and β8 of the tapered portion is β9 > β7, β8. In other words, β9 at any position on the slope is greater than β7 and β8.

[0100] Table 6 shows the parameters related to the shape of the optical guide component used in the simulation, and Table 7 shows the simulation results. The taper angles β7 of the upper and lower surfaces of the tapered section were 1.2° to 5.0°, and the taper angles β8 of the left and right surfaces were 3.1° to 10.2°. On the other hand, the inclination angle β9 of the slanted surface of the elliptical frustum of the incident section with respect 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 there are inclination angles β9 on the minor axis a3 side and the major axis b3 side (see Figures 11 and 12), both are listed in Table 6. The size of the incident surface was set to 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 incident section length L2 was varied between 0.7 mm and 1.9 mm depending on the total length L. The ratio of the incident section length L2 to the tapered section length L1 is in the range of 14-42%.

[0101] [Table 6]

[0102] [Table 7]

[0103] In cases where the total length L was 3, 4, and 5 times the length D of the diagonal of the emission surface (Examples 35-39), the homogeneity of the emission surface illuminance distribution was excellent, and the divergence angle was very small. In cases where the total length L was 2 times the length D of the diagonal of the emission surface (Examples 32-34), the divergence angle increased as the incident surface size increased, but it remained sufficiently small for incident surface sizes of 0.3 mmφ and 0.4 mmφ. There was a variation of about 5% in the homogeneity of the emission surface illuminance distribution, but it was still sufficiently homogeneous. In case where the total length L was 1.5 times the length D of the diagonal of the emission surface (Example 31), the divergence angle remained small, but the homogeneity of the emission surface illuminance distribution showed a large variation of about 10%.

[0104] Figure 40 shows the ray tracing simulation results for Example 37. In the figure, a rectangular plane appears in the middle, which represents the exit surface of the optical guide component of the present invention. The left side of this rectangular plane is the ray trajectory within the optical guide component, and the right side is the trajectory of the ray that exited the exit surface. Figures 41 and 42 show the illuminance distribution in the X direction (horizontal) and Y direction (vertical) at the exit surface. It can be seen that the illuminance distribution at the exit surface is extremely homogeneous. Figure 43 shows the divergence angle at the exit surface, with the dark solid line representing the divergence angle in the X direction and the light solid line representing the divergence angle in the Y direction. Both are extremely small FWHM values ​​of ±7.2° and ±7.5°, respectively, indicating that angle narrowing has been achieved.

[0105] Figure 44 shows the results of the ray tracing simulation for Example 31. Similar to Figure 40, a rectangular plane appears in the middle of the figure, representing the exit surface of the optical guide component of the present invention. The left side of this rectangular plane represents the ray trajectory within the optical guide component, and the right side represents the trajectory of the ray that exited the exit surface. Figures 45 and 46 show the illuminance distribution in the X direction (horizontal) and Y direction (vertical) at the exit surface. The illuminance distribution at the exit surface shows a variation of around 5% in the X direction, and the variation in the Y direction exceeds 10% at the edges. In other words, it was found that the homogeneity of the illuminance distribution at the exit surface is poor. 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 ​​are small, ±12.9° and ±9.4°, indicating that there is no problem with straight-line propagation.

[0106] As can be seen from Table 7, in Examples 35, 36, 38, and 39, where the total length L is more than three times the length D of the diagonal of the exit surface, it was found that, similar to Example 37, the illuminance distribution on the exit surface was excellent, the divergence angle was small, and the straight-line propagation was excellent. On the other hand, in the case where the total length L is twice the length D of the diagonal of the exit surface, the illuminance distribution on 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 are considered to satisfy both the uniformity of the illuminance distribution and the divergence angle, but Example 34, which has a large incident surface size, had a large divergence angle and was judged not to have sufficient performance. [Examples]

[0107] Next, an embodiment relating to the optical guide component of the fourth invention of this application is shown. In [Embodiment 3], which is an embodiment of the third invention of this application, the simulation results were for an optical guide component in which an incident portion of the shape shown in Figure 13, i.e., an elliptical frustoconical shape, is continuously formed on the upper surface of a solid frustoconical pyramid with taper angles β7 and β8. However, in this [Embodiment 4], the incident portion is a circular CPC shape, as shown in Figure 15, where the incident surface of the incident portion is circular, the base is square, and the inclined surface is a CPC (internal reflective paraboloid). The tapered portion is the same as that shown in the third embodiment [Embodiment 3], a solid frustoconical pyramid with taper angles β7 and β8. That is, a simulation was performed for an optical guide component in which an incident portion of a circular CPC is continuously formed on the tapered portion of a solid frustoconical pyramid. In this case, the inclination angle β of the tangent plane at any position on the inclined surface of the circular CPC of the incident portion. 10 Between the tapered section and the taper angle, β 10 >β7 and β8 are in a relationship. That is, β 10 These values ​​are greater than β7 and β8 (see Figure 48).

[0108] Table 8 shows the parameters related to the shape of the optical guide components used in the simulation, and Table 9 shows the simulation results. The taper angles β7 of the upper and lower surfaces of the tapered section are 0.5° to 5.3°, and the taper angles β8 of the left and right surfaces are 3.0° to 11.2°. On the other hand, in the circular CPC of the incident section, the inclination angle β with respect to the optical axis is β 10 The angle is greatest at the position adjacent to the incident surface and least at the horizontal and vertical ends. These angles are also listed in Table 8. The incident surface was a circle with a diameter of 0.3 mm, 0.4 mm, or 0.5 mm. The incident section length L2 varied between 0.8 mm and 1.5 mm, depending on the total length L. The ratio of the incident 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 emission surface (Examples 44-49), the homogeneity of the emission surface illuminance distribution was excellent, and the divergence angle was small. In cases where the total length L was 2 times the length D of the diagonal of the emission surface (Examples 42 and 43), there was a variation of about 5% in the homogeneity of the emission surface illuminance distribution, and the divergence angle was slightly larger. In case where the total length L was 1.5 times the length D of the diagonal of the emission surface (Example 41), there was a variation of about 10% in the homogeneity of the emission surface illuminance distribution, and the divergence angle exceeded ±15°.

[0112] For Example 47, the ray tracing simulation results, the illuminance distribution in the X and Y directions at 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 homogeneous, the divergence angle is small, and the ray propagation is excellent.

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

[0114] From the results of [Example 1], [Example 2], [Example 3], and [Example 4] described above, it was found that for cases where the incident section is a rectangular CPC, a second truncated square pyramid, an elliptical truncated pyramid, and a circular CPC, there are examples with good results and examples with insufficient results, but the boundary between them can be distinguished by the ratio of the total length L to the length D of the diagonal of the exit surface (L / D). In the case of a rectangular CPC, the results were good even when L / D was 1.5, so it is thought that the results were insufficient when L / D was 1.5 or less. In the case of 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 homogeneity 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 incident section is an elliptical frustum, the results were good when L / D was 2 or greater. However, when L / D reached 1.5, although the divergence angle was small, the homogeneity 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 incident section is a circular CPC, the results were good when L / D was 3 or greater. However, when L / D was 2 or less, although the divergence angle was small, the homogeneity of the illuminance distribution at the exit surface became insufficient. Therefore, the boundary is considered to be between L / D 2 and 3. To determine these boundary L / D values, additional simulations were performed for the examples. 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, where the incident section was a rectangular CPC and the total length L was 1.2 times the diagonal D of the exit surface, both the illuminance distribution in the X direction and the illuminance distribution in the Y direction at the exit surface showed variations of more than 10%, as shown in Figures 57 and 58, indicating a lack of homogeneity. In Example 52, where the incident section was an elliptical frustum and the total length L was 1.8 times the diagonal D of the exit surface, the divergence angle at the exit surface was good, but both the illuminance distribution in the X direction and the illuminance distribution in the Y direction showed variations of more than 5%, as shown in Figures 59 and 60, indicating a lack of sufficient homogeneity. In contrast, in Examples 53 and 54, where the incident section was a square frustum and the total length L was 2.4 times the diagonal D of the exit surface, both showed small divergence angles and excellent homogeneity with variations of 5% or less in the illuminance distribution in the X direction and the Y direction. The results for Example 54 are shown in Figures 61 and 62. In Examples 55 and 56, where the incident section was a circular CPC and the total length L was 2.4 times the diagonal D of the exit plane, both exhibited small divergence angles and excellent homogeneity, with variations in illuminance distribution in the X and Y directions being 5% or less. The results for Example 55 are shown in Figures 63 and 64.

[0119] From the evaluation results regarding the boundary values ​​described above, the following was found: When the incident part is a rectangular CPC, good results are obtained for both the homogeneity of the illuminance distribution on the exit surface and the narrowing of the divergence angle when L / D is between 1.5 and 5, but homogeneity deteriorates when L / D reaches 1.2. When the incident part is an elliptical frustum, good results are obtained for both the homogeneity of the illuminance distribution on the exit surface and the narrowing of the divergence angle when L / D is between 2 and 5, but homogeneity deteriorates when L / D reaches 1.8. When the incident part is a square frustum, good results are obtained for both the homogeneity of the illuminance distribution on the exit surface and the narrowing of the divergence angle when L / D is between 2.4 and 5, but homogeneity deteriorates when L / D reaches 2.0. Even when the incident section is a circular CPC, good results are obtained in terms of both the homogeneity of the illuminance distribution on the exit surface and the narrowing of the divergence angle when the L / D ratio is 2.4 to 5, but the homogeneity deteriorates when the L / D ratio becomes 2.0. [Examples]

[0120] Next, the optical guide components of Embodiment 5 of the First Invention of this Application, shown in Table 1, were arranged in five rows in the height direction and five columns in the width direction without any gaps to obtain an integrated optical guide component with five rows and five columns of optical guide components. Then, LED elements were placed on the incident surface of the incident portion of each of the five rows and five columns of optical guide components to obtain a surface-emitting illumination device. Then, a ray tracing simulation (Figure 65) was performed to evaluate the illuminance distribution at the exit surface of the surface-emitting illumination (Figures 66 and 67). The left side of Figure 65 shows the ray trajectory within the optical guide component, and the ray beam appears dense. In the center is the exit surface of the tapered section (a rectangle indicating that it is the exit surface is visible), and to the right of the exit surface of the tapered section is outside the optical guide component, where the light rays diverge from the exit surface and appear sparse. Looking at the illuminance distribution in the X direction and the illuminance distribution in the Y direction, small heterogeneity is observed due to the influence of stray light, which is thought to be from adjacent optical guide components, since each optical guide component is in contact with the others. Such heterogeneity can be avoided by arranging each light guide optical component with a spacing of approximately 0.1 mm to 0.3 mm. Furthermore, by placing a focusing lens behind such a light source, the homogeneity of the light incident on the display device (light bulb) of the projection-type display device can be considered to be at a completely acceptable level. [Examples]

[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 and investigated how the homogeneity of the illuminance distribution and the divergence angle change when the taper angle is widened to increase the output surface area and when the taper angle is narrowed to decrease the output surface area. The results are shown in Table 13. The parameters used in the simulation are shown in Table 14. In both the case of Example 2 where the taper angle was widened to increase the output surface area (Figure 68) and the case where the taper angle was narrowed to decrease the output surface area (Figure 69), the homogeneity of the illuminance distribution deteriorated significantly. Similarly, in Example 4 where the taper angle was widened to increase the output surface area, the illuminance distribution deteriorated extremely. On the other hand, in Example 4 where the taper angle was narrowed to decrease the output surface area, the homogeneity of the illuminance distribution improved somewhat, but the divergence angle became extremely large and the narrowing of the angle was not achieved. In this study, there were no taper angles that could further improve the results of Examples 2 and 4 described in Table 1.

[0122] [Table 13]

[0123] [Table 14]

[0124] Next, to investigate the effects of changing the incident section length L2 on the illuminance distribution and divergence angle, simulations were performed using Example 2 in Table 1 for [Example 1] as the standard model, for cases where the incident section was 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. Both shortening and lengthening the incident section significantly worsened the homogeneity of the emitted light (illuminance distribution). When the section was shortened, the illuminance distribution in the X direction increased significantly near the center, while when the section was lengthened, conversely, the illuminance distribution in the X direction diped significantly near the center. In other words, in this study, no incident section length greater than that of Example 2 existed.

[0125] [Table 15]

[0126] [summary] All the data from the simulation is summarized in Table 16. As mentioned above, the following can be concluded. (1) In conventional tapered light tunnels, unless the total length of the tapered light tunnel is at least six times the diagonal of the exit surface, homogeneity of the illuminance distribution at the exit surface and narrowing of the divergence angle of light incident from the incident surface cannot be achieved. (2) When an incident section consisting of a rectangular CPC is provided continuously with the tapered section, if the angles (β3 and β4) that the tangent planes of the rectangular CPC make with the optical axis at any of the upper and lower sides and left and right sides are set to be larger than the corresponding tapered section angles (β1 and β2), then the overall length (L) can be short, such that it is 1.5 to 5 times the diagonal D of the tapered section's exit surface, while maintaining uniformity of the illuminance distribution at the exit surface and narrowing of the divergence angle of the light incident from the incident surface, thereby enabling high performance and miniaturization of the optical guide component. At this time, the ratio L2 / L1 of the incident section length to the tapered section length is in the range of 2.4% to 13.4%, the angle β1 of the upper and lower surfaces of the tapered section is in the range of 1.9° to 5.8°, and the angle β2 of the left and right surfaces of the tapered section is in the range of 4.1° to 13.8°. (3) When an incident section consisting of a second truncated square pyramid is provided in conjunction with the tapered section, if the angles (β5 and β6) that the upper and lower surfaces and left and right surfaces forming the second truncated square pyramid make with the horizontal and vertical planes containing the optical axis are set to be larger than the corresponding tapered section angles (β1 and β2), the optical guide component can be made high-performance and miniaturized with a short overall length (L) of 2.4 to 5 times the diagonal D of the tapered section exit surface. 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 angle β1 of the upper and lower surfaces of the tapered section is in the range of 1.1° to 3.3°, and the angle β2 of the left and right surfaces of the tapered section is in the range of 3.3° to 6.4°. (4) When an incident section consisting of an elliptical frustum is provided continuously with the tapered section, if the angle of inclination of the elliptical frustum slope with the optical axis (β9) is set to be greater than the taper angles of the tapered section (β7 and β8) at any position of the sloping surface of the elliptical frustum, then the overall length (L) can be short, such that it is between 2 and 5 times the diagonal D of the tapered section's exit surface. This allows for the achievement of homogeneity in the illuminance distribution at the exit surface and a narrowing of the divergence angle of light incident from the incident surface, enabling the optical guide component to be made high-performance and miniaturized. 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 angle β7 of the upper and lower surfaces of the tapered section is in the range of 1.2° to 4.2°, and the angle β8 of the left and right surfaces of the tapered section is in the range of 3.1° to 7.3°. (5) When a circular CPC incident section is provided continuously with the tapered section, the angle (β) between the tangent plane and the optical axis is such that the tangent plane makes contact with the optical axis at any of the positions of the sides forming the circular CPC. 10 If the angle of the tapered section (β7 and β8) is set to be greater than the taper angle of the tapered section, the total length (L) can be short, such that it is 2.4 to 5 times the diagonal D of the tapered section's exit surface. This allows for the achievement of uniform illuminance distribution and narrowing of the divergence angle at the exit surface, enabling high-performance and miniaturization of the light guide optical component. In this case, the ratio L2 / L1 of the incident section length to the tapered section length is in the range of 11.3% to 16.7%, the angle β7 of the upper and lower surfaces of the tapered section is in the range of 0.5° to 3.5°, and the angle β8 of the left and right surfaces of the tapered section is in the range of 3.0° to 8.1°. (6) By arranging multiple light guide optical components as described in (2) to (5) above, a light guide optical component with a uniform illuminance distribution over a wide emission surface and a small divergence angle can be obtained. (7) By arranging the LED light source in contact with the incident surface of the light guide optical component described in (2) to (6) above, a lighting device with a uniform illuminance distribution and a small divergence angle can be obtained. (8) By using the lighting device described in (7) above, lens means, light bulb, magnifying optical lens system, and screen, a projection display device with a uniform illuminance distribution with minimal color unevenness can be obtained.

[0127] [Table 16] [Explanation of Symbols]

[0128] 101... Rectangular prism-shaped light tunnel 102...Incident surface of a rectangular prism-shaped light tunnel 103... Exit surface of a rectangular prism-shaped light tunnel 104...Side view of a rectangular prism-shaped light tunnel 201...Taperlite Tunnel 202...Induction surface of a tapered tunnel 203... Exit surface of tapered lite tunnel 204... Side view of a tapered lite tunnel 301...An example of a light guide optical component of the present invention 302...Incident surface of an example of a light guide optical component of the present invention 303... An example of the light-guiding optical component of the present invention: the emission surface 304...Left and right side views of a tapered portion of an example of a light guide optical component of the present invention 305...Upper and lower sides of a tapered portion of an example of a light guide optical component of the present invention 306... The upper surface of the tapered portion (which is also the bottom surface of the incident portion) of an example of the light guide 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 guide optical component of the present invention 308...Left and right side views of the incident portion of an example of the light guide optical component of the present invention 309...An example of a lens portion of an example of a light guide optical component of the present invention 310... An example of the light-guiding optical component of the present invention, the emission surface of an example of the lens portion. 701...LED light source 702... Focusing lens 703... Primary lens 704...Light bulb 705...Reflector 706... Enlarged projection section

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