Light guide optical component, illumination device using light guide optical component, and projection type display device using illumination device

Abstract

To provide a light guide optical component that can capture more light from an LED light source than a conventional product, and can form a light flux with uniform illuminance distribution and a small divergence angle on an emission surface, an illumination device using the light guide optical component, and a projection type video display device using the illumination device.SOLUTION: A bottom surface of a tapered part of a first truncated square pyramid having an inclination angle of β1 in a horizontal direction and β2 in a vertical direction is a light emitting surface, and an upper surface is an incidence surface. A second truncated square pyramid having the incidence surface as a bottom surface is continuously formed as an incidence part. A light guide optical component consists of the incidence part and the tapered part. A plurality of the light guide optical components can be integrated to form a light guide optical component. When an LED element is caused to abut against the incidence surface of the incidence part of the light guide optical component, an illumination device can be formed. The illumination device can be used as illumination for a projection type display device.SELECTED DRAWING: Figure 16

Description

[Technical Field]

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

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

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

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

[0005] In order to ensure that the image projected onto the screen is bright and uniform, it is important to capture as much light as possible from the light source and illuminate the display element uniformly, and various measures have been taken to ensure that the light emitted from the light source illuminates the display element with uniform illuminance.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0027] The problem that the present invention aims to solve is to provide a light-guiding optical component that can take in more light from an LED light source than conventional technology, has uniform emitted illuminance, and can irradiate a light valve with a light beam with a small divergence angle, an illumination device that uses the light-guiding optical component, and a projection-type image display device that uses the illumination device. [Means for solving the problem]

[0028] In order to solve the above-mentioned problems of the prior art, the first invention of the present application provides a rectangular or square incident surface (when H1=W1) having a height H1 and a width W1, a rectangular exit surface (H2>H1, W2>W1) having a height H2 and a width W2, a solid tapered portion of a first truncated quadrangular pyramid that widens in the direction of light travel at an angle β1 in the height direction and an angle β2 in the width direction with respect to the optical axis, and an incident portion made of a second truncated quadrangular pyramid that has a square or rectangular top surface having a height H3 and a width W3 and that is further formed continuously with the square or rectangular bottom surface having the height H1 and width W1. the second truncated quadrangular pyramid has a length L2, the angle β3 between the optical axis and any of the four side surfaces of the second truncated quadrangular pyramid is larger than β1 and β2, the sum of the tapered portion length L1 and the second truncated quadrangular pyramid length L2 (total length L) is 1.5 to 5 times the diagonal length D2 of the exit surface, the length L2 of the second truncated quadrangular pyramid is in the range of 1 / 9 to 1 / 42 of the tapered portion length L1, the β1 is in the range of 1.9° to 5.8°, and the β2 is in the range of 4.1° to 13.8°. Here, the size of the rectangular exit surface with height H2 and width W2 is equal to or at least similar to the size of a display element illuminated by the light-guiding optical component of the present invention.

[0029] Figure 3 shows an example of the configuration of a light-guiding optical fixture of the present invention. 301 is an overall view of a light tunnel with a double-taper structure consisting of an entrance section and a tapered section. The top surface 306 of a first truncated quadrangular pyramid, which is the tapered section that flares out, is formed continuously with the entrance section, which is the second truncated quadrangular pyramid. The top surface 302 of the second truncated quadrangular pyramid is the entrance surface for light from the light source, and the bottom surface 303 of the first truncated quadrangular pyramid of the tapered section that flares out is the exit surface.

[0030] Here, the inclination angle β1, which is the angle between the optical axis and the upper and lower surfaces of the tapered portion, and the angle β2, which is the angle between the optical axis and the left and right surfaces of the tapered portion, are expressed as follows: β1=arctan{(H2-H1) / 2L1}, β2=arctan{(W2-W1) / 2L1) (See Figures 4 and 5.) The parallelism of light reflected by the tapered surface improves by 2β1 in the height direction for each reflection on the top and bottom surfaces, and by 2β2 in the width direction for each reflection on the left and right surfaces. In the present invention, the sum of the length L1 of the tapered portion and the length L2 of the incident portion, i.e., the total length L, is 1.5 to 5 times the diagonal length D2 of the exit surface, and light from the light source can be made uniform over a shorter length than conventional methods.

[0031] In the present invention, a tapered second truncated square pyramid is formed as the incident portion, with the top surface 306 of the first truncated square pyramid as its base, and its top surface 302 serves as the incident surface for light from the light source. The four side surfaces of the second truncated square pyramid are typically trapezoidal. However, the side surfaces of the second truncated square pyramid are not limited to trapezoidal shapes. They may also be internally reflecting paraboloids (in which case the truncated square pyramid is called a rectangular CPC) or single curved surfaces that bulge outward. Furthermore, as will be described later in the second invention, an elliptical truncated cone may be used instead of a truncated square pyramid. The important point is that the angle β3 between the truncated square pyramid and the optical axis is greater than the inclination angles β1 and β2 of the tapered portion at any position. That is, light incident on the incident surface 302 at a shallow angle first strikes the side surface of the incident portion, where the incident angle suddenly decreases and proceeds to the tapered portion, as shown in FIG. 6. In the lighting device, the LED element is disposed in contact with the incident surface 302 on the upper surface of the tapered truncated quadrangular pyramid.

[0032] FIG. 7 shows how light incident on the light-guiding optical component of the present invention is repeatedly reflected at the entrance portion and the tapered portion, and reaches the exit surface.

[0033] In the present invention, the inclination angle β1 of the tapered portion must be between 1.9° and 5.8°. If it is less than 1.9°, the divergence angle at the exit surface becomes large. If it exceeds 5.8°, the uniformity of the illuminance distribution at the exit surface deteriorates.

[0034] Similarly, in the present invention, the inclination angle β2 of the tapered portion must be between 4.1° and 13.8°. If it is less than 4.1°, the divergence angle at the exit surface becomes large. If it exceeds 13.8°, the uniformity of the illuminance distribution at the exit surface deteriorates.

[0035] In the present invention, the sum (total length L) of the length L1 of the tapered portion of the first quadrangular pyramid and the length L2 of the second quadrangular pyramid can be 1.5 to 5 times the diagonal length D2 of the exit surface. If the sum is less than 1.5 times, conditions for improving the homogeneity of the exit light could not be found. Even with known tapered light tunnels, if the sum exceeds 5 times and reaches 6 times, a roughly uniform light beam with a small divergence angle can be obtained at the exit surface. However, tapered light tunnels with a sum of 5 times or less could not obtain a uniform light beam with a small divergence angle.

[0036] In the present invention, the length L2 of the incident portion can be set in the range of 1 / 9 to 1 / 42 of the length L1 of the tapered portion. If it is greater than 1 / 9, conditions for achieving both uniformity of the emitted light and narrowing of the divergence angle could not be found. If it is less than 1 / 42, the total length will simply become longer and there will be no advantage.

[0037] Furthermore, the second invention of the present application has a solid tapered portion consisting of a truncated square pyramid that widens from a rectangular entrance surface of height a1 and width b1 (square when a1=b1) to a rectangular exit surface of height H2 and width W2 by β4 in the height direction and β5 in the width direction relative to the optical axis, and further has the rectangle of height a1 and width b1 (square when a1=b1) as the bottom surface and an ellipse with a minor axis a2 and a major axis b2 as the top surface, and the length of the truncated elliptical cone is L3, The light-guiding optical component is characterized in that the angle β6 formed with the optical axis at any position of the elliptical truncated cone is larger than β4 and β5, the sum of the length L1 of the tapered portion and the length L3 of the elliptical truncated cone (total length L) is 1.5 to 5 times the length D2 of the diagonal of the light-emitting surface, the height L3 of the elliptical truncated cone is in the range of 1 / 9 to 1 / 42 of the length L1 of the tapered portion, β4 is in the range of 1.9° to 5.8°, and β5 is in the range of 4.1° to 13.8°.

[0038] The difference from the first invention of the present application is that the entrance portion is not a truncated square pyramid of length L2 but an elliptical truncated cone of length L3 (see FIG. 8). Here, the side surface of the elliptical truncated cone does not necessarily have to be a straight line, as in the case of the truncated square pyramid of the first invention, and may be an internal reflection paraboloid or a single curved surface that bulges outward (see FIG. 14).

[0039] In this case, the angle β4 between the upper and lower surfaces of the tapered portion and the optical axis, and the angle β5 between the left and right surfaces and the optical axis are β4=arctan{(H2-a1) / 2L1}, β5=arctan{(W2-b1) / 2L1) (See Figs. 9 and 10.) The parallelism of the light reflected by the tapered surface is improved by 2β4 in the height direction and 2β5 in the width direction with each reflection.

[0040] In Figure 8, the bottom surface 303 of the flared truncated quadrangular pyramid is the rectangular light emission surface. In the present invention, a tapered truncated elliptical cone is formed continuously with the top surface of the truncated quadrangular pyramid as its bottom surface, and its top surface is elliptical and serves as the light incidence surface 302. In the lighting device, the LED element is abutted against the elliptical light incidence surface 302.

[0041] Light incident at a shallow angle on the entrance surface 302 of the entrance portion of the elliptical truncated cone is reflected by the inner surface of the elliptical truncated cone, which has a curvature (β6) greater than the inclination angles β4 and β5 of the tapered portion, significantly reducing the angle with the optical axis. After entering the tapered portion, the angle with the optical axis decreases by approximately 2β4 or 2β5 with each reflection before reaching the exit surface 303. The length L1 of the tapered portion can be made significantly shorter than the length of a conventional tapered light tunnel. Specifically, the sum of the length L1 of the tapered portion and the length L3 of the elliptical truncated cone (total length L) can be between 1.5 and 5 times the diagonal length D2 of the exit surface.

[0042] 3 and 8, the incident light is a mixture of rays that form a large angle with the optical axis and rays that form a small angle with the optical axis, but by selectively reflecting only the rays with a large incident angle from the side surface of the incident portion, the angle that the reflected rays form with the optical axis becomes significantly smaller, whereas the rays that form a small angle with the optical axis when they are incident on the incident surface enter without being reflected from the side surface of the incident portion and are reflected only by the side surface of the tapered portion, so the number of reflections does not decrease. This makes it possible to narrow the angle of the light rays emitted from the exit surface without significantly reducing the uniformity of the light distribution on the exit surface.

[0043] Furthermore, the double taper structure, which combines the shapes of the entrance and tapered sections, allows for greater design freedom compared to the tapered light tunnel with a simple quadrangular pyramid shape shown in Figure 2, and independently adjusting the shapes of the entrance and tapered sections can contribute to homogenizing the light distribution on the exit surface.

[0044] As a result, in a short light tunnel whose total length L is between 1.5 and 5 times the diagonal length D2 of the exit surface, it is possible to achieve both homogenization of the light distribution at the exit surface and a small divergence angle of the exit light.

[0045] The shapes of the incident portion in the above invention are shown in Figures 11, 12, 13, and 14. Figure 11 shows that the incident portion is a truncated quadrangular pyramid, and Figure 12 shows that although the incident portion is a truncated quadrangular pyramid, the side surfaces are not trapezoidal but are paraboloids (called rectangular CPCs in this case) or single curved surfaces that bulge outward. Figure 13 shows that the incident portion is a truncated elliptical cone. Figure 14 shows that the side surfaces of the truncated elliptical cone are paraboloids or single curved surfaces that bulge outward.

[0046] In the first or second invention, when the exit surface or the entrance surface is expressed as a rectangle, the four corners do not necessarily have to be right angles in the strict sense, and the corners may be rounded in order to prevent damage due to contact.

[0047] The third invention of the present application is the first and second inventions, in which a condensing lens or a diverging lens is integrated at the position of the exit surface of the light-guiding optical component, as shown in Fig. 15. The condensing lens or diverging lens used here typically has one side that is approximately flat and is integrated with the exit surface, and the other side is a convex or concave lens with a curvature. This eliminates loss due to divergence of light components with a large divergence angle at the position of the exit surface, allowing light to be irradiated forward from the condensing lens, and when a diverging lens is used, the irradiation area can be increased.

[0048] The fourth and fifth inventions of the present application relate to light-guiding optical components in which a plurality of light-guiding optical components disclosed in the first and second inventions of the present application are integrated. The term "multiple" may refer to two, or may be, for example, an M-tiered, N-row arrangement. When referring to an M-tiered, N-row arrangement, at least one of M and N is equal to or greater than two. When configuring a light source device, the number and configuration of the light-guiding optical components are set equal to the number of LED elements, and the incident surfaces of the light-guiding optical components are arranged facing the LED elements. For example, if the LED elements are arranged in two columns and three rows, the light-guiding optical components are also integrated in two columns and three rows, resulting in a lighting device in which the incident surfaces of the light-guiding optical components are arranged in contact with the LED elements. In the case of an M-tiered, N-row arrangement, light-guiding optical components may not be arranged at the four corners, or a portion of the center may be omitted, for ease of handling, to prevent damage due to contact, or for ease of manufacturing. Even in these cases, there is no significant problem with the uniformity of illuminance on the illuminated surface.

[0049] 16 and 17 show a 5-column, 5-row light-guiding optical component according to one embodiment of the fourth invention, with Fig. 16 being an overall perspective view and Fig. 17 being a front view seen from the light incident side. In this embodiment, a condenser lens is integrated with the exit surface of each light-guiding optical component. In this embodiment, the 5-column, 5-row configuration has an exit surface whose size is similar to the shape of the light valve, which is the display element.

[0050] The sixth aspect of the present invention is a lighting device in which an LED element is disposed in contact with the incident surface of the incident part of the light-guiding optical component according to the first, second, fourth, or fifth aspect of the present invention. Whichever light-guiding optical component is used, a lighting device with a uniform illuminance distribution on the exit surface can be obtained.

[0051] The seventh invention of the present application is a projection display device in which a light beam from the exit surface of the lighting device according to the sixth invention is focused and irradiated onto a light valve, which is a display element, by a focusing lens system, and the image generated by the display element is enlarged by a magnifying projection optical system and projected onto a screen.

[0052] An example of the configuration of a projection display device is shown in Figure 18. Examples of light valves for projection display devices include transmissive liquid crystal display panels, reflective liquid crystal display panels, and DMDs (digital micromirror devices), but according to the present invention, parallel light with uniform illuminance can be obtained, so it is particularly effective for DMD display elements that are arranged at a distance from the light source and light-guiding optical components.

[0053] Since it is assumed that the real image on the exit surface 303 will be projected onto a display element such as a liquid crystal display element or DMD used in a projector, thereby illuminating with a uniform intensity, it is desirable that the aspect ratio of the exit surface 303 be 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]

[0054] According to the light-guiding optical component of the present invention, by separately controlling the parameters of the incident portion and the tapered portion, and by keeping the ratio of the length L2 of the incident portion to the length L1 of the tapered portion within a predetermined range and further keeping the inclination angle of the tapered portion within a predetermined range within a total length not exceeding a predetermined length, light from the light source reaches the exit surface of the light-guiding optical component as parallel light that forms a small angle with the optical axis and has a small divergence angle, even over a short length that was not achievable in conventional components, thereby obtaining exit light with an extremely uniform illuminance distribution and a small divergence angle at the exit surface. Furthermore, by arranging and integrating a plurality of light-guiding optical components, a light-guiding optical component with a large area can be produced.

[0055] The lighting device using the light-guiding optical component and LED light-emitting element of the present invention can provide a lighting device with a uniform illuminance distribution and a small divergence angle. Furthermore, the lighting device can emit light over a wide area by integrating a plurality of light-guiding optical components and LED light-emitting elements.

[0056] In a projection display element using the illumination device of the present invention, the light valve is illuminated with illumination having a very uniform illuminance and a narrow divergence angle, making it possible to project an image with excellent illuminance distribution onto a screen.The illumination device of the present invention can irradiate parallel light having a uniform illuminance distribution and a small divergence angle, making it suitable for use in a projection display device using a DMD with a wide gap between the illumination device and the light valve. [Brief explanation of the drawings]

[0057] [Figure 1] FIG. 10 is a diagram showing the reflection of light in a rectangular prism-shaped light tunnel. [Figure 2] FIG. 10 is a diagram showing the reflection of light in a tapered light tunnel with a flared truncated square pyramid shape. [Figure 3] 1 is a diagram showing an example of the configuration of a light-guiding optical component according to a first aspect of the present invention. [Figure 4] 1 is a side view of an example of the configuration of a light-guiding optical component according to a first aspect of the present invention. [Figure 5] 1 is a plan view of an example of the configuration of a light-guiding optical component according to a first aspect of the present invention. [Figure 6] FIG. 2 is a diagram showing the path of light incident on an incident portion of the first invention of the present application. [Figure 7] 1 is a diagram showing how light incident on an incident surface exits from an exit surface in the first invention of the present application. FIG. [Figure 8] FIG. 3 is a diagram showing an example of the configuration of a light-guiding optical component according to a second aspect of the present invention. [Figure 9] FIG. 4 is a side view of an example of the configuration of a light-guiding optical component according to a second aspect of the present invention. [Figure 10] FIG. 4 is a plan view of an example of the configuration of a light-guiding optical component according to a second aspect of the present invention. [Figure 11] 1 is a diagram showing a truncated quadrangular pyramid as an example of an incident portion of a light-guiding optical component according to a first aspect of the present application. [Figure 12] FIG. 10 is a diagram showing a modified example of a truncated quadrangular pyramid (four side surfaces of which are CPC curved surfaces bulging outward) that is an example of the incident section of the light-guiding optical component of the first invention of the present application. [Figure 13] 10 is a diagram showing an elliptical truncated cone as an example of an incident portion of an optical guiding component according to a second aspect of the present invention. FIG. [Figure 14] 10 is a diagram showing another aspect of an elliptical truncated cone, which is an example of the incident portion of the optical guiding component of the second invention of the present application. FIG. [Figure 15] FIG. 10 is a diagram showing an example in which a condenser lens is integrated with the exit surface of a light-guiding optical component, which is an example of the third invention of the present application. [Figure 16] FIG. 10 is a perspective view showing an example of a light-guiding optical component in which a plurality of light-guiding optical components are arranged and integrated, which is a fourth or fifth invention of the present application. [Figure 17] FIG. 10 is a plan view showing an example of a light-guiding optical component in which a plurality of light-guiding optical components are arranged and integrated, which is a fourth or fifth invention of the present application. [Figure 18] 10 shows an example of the configuration of a projection display device according to a seventh aspect of the present invention, which uses an example of an illumination device according to a sixth aspect of the present invention. [Figure 19] 4 is a diagram showing an example of the results of a ray tracing simulation of a light beam incident on the light-guiding optical component of the first invention. FIG. [Figure 20]3 is a diagram showing an example of the illuminance distribution in the width direction on the exit surface of a light beam that has entered the light-guiding optical component of the first invention. FIG. [Figure 21] FIG. 1 is a diagram showing an example of the illuminance distribution in the height direction on the exit surface of a light beam incident on a first light-guiding optical component of the present invention. [Figure 22] 3 is a diagram showing an example of the distribution of divergence angles in the X direction (width direction) and the Y direction (height direction) on the exit surface of a light beam that has entered the light-guiding optical component of the first invention. FIG. [Figure 23] 6 is a diagram showing another example of the results of a ray tracing simulation of light rays incident on the light-guiding optical component of the first invention. FIG. [Figure 24] 10 is a diagram showing another example of the illuminance distribution in the X direction (width direction) on the exit surface of the light beam that has entered the light-guiding optical component of the first invention. FIG. [Figure 25] FIG. 10 is a diagram showing another example of the illuminance distribution in the Y direction (height direction) on the exit surface of a light beam that has entered the first light-guiding optical component of the present invention. [Figure 26] 10 shows another example of the distribution of divergence angles in the X and Y directions on the exit surface of a light beam incident on a light-guiding optical component of the present invention. [Figure 27] 10 is an example of a result of a ray tracing simulation of light rays incident on a tapered light tunnel, which is a comparative example. [Figure 28] 10 is an example showing an illuminance distribution in the X direction on the exit surface of a light ray that has entered a tapered light tunnel that is a comparative example. [Figure 29] 10 is an example showing the Y-direction illuminance distribution on the exit surface of a light beam incident on a tapered light tunnel that is a comparative example. [Figure 30] FIG. 10 is a diagram showing the results of a ray tracing simulation of light rays incident on a light-guiding optical component in which a plurality of light-guiding optical components (5 rows and 5 columns) according to the fourth invention are integrated. [Figure 31] FIG. 10 is a diagram showing the X-direction illuminance distribution of light rays incident on a light-guiding optical component in which a plurality of light-guiding optical components (5 rows and 5 columns) according to the fourth invention are integrated. [Figure 32] FIG. 10 is a diagram showing the Y-direction illuminance distribution of light rays incident on a light-guiding optical component in which a plurality of light-guiding optical components (5 rows and 5 columns) according to the fourth invention are integrated. [Figure 33] FIG. 10 is a diagram showing the change in the X-direction illuminance distribution when the taper angle is increased, with Example 2 being used as a standard. [Figure 34] FIG. 10 is a diagram showing a change in the X-direction illuminance distribution when the taper angle is reduced, with Example 2 being used as a standard. DETAILED DESCRIPTION OF THE INVENTION

[0058] Simulation results for examples of the present invention and comparative examples are shown below, and the obtained data are summarized in tables, and for some results, the obtained data is published as is. [Example]

[0059] In the light-guiding optical component according to the present invention, as a means for illuminating a display element (light valve) in a projector, an illumination device using a scattering light source 701 consisting of an LED element and the light-guiding optical component (quadratic pyramidal truncated shape) of the first invention of the present application, and a projection display device using the illumination device, were configured, as shown in FIG.

[0060] In the simulations that follow, an LED element with a wavelength of 550 nm, a light-emitting surface diameter of 0.255 mm (this diameter corresponds to 1 / 10 of the diagonal angle of the exit surface of the light-guiding optical components that will often be used in the simulations that follow), and a FWHM of ±60° was used as the LED light source. The design wavelength was 550 nm, and the refractive index n of the glass that makes up the light-guiding optical components and tapered light tunnels of the present invention was 1.5185. Here, FWHM refers to the full width at half maximum of the LED luminance distribution.

[0061] In the optical system of FIG. 18, the light-guiding optical component 301 was the first light-guiding optical component of the present invention, consisting of a tapered section and an incident section, as shown in FIG. 3, and the conventional tapered light tunnel with a truncated quadrangular pyramid shape, as shown in FIG. 2. The ray trajectories of the incident light were simulated (ray tracing simulation) to determine how the light rays propagated to and exited from the exit surface 303. The results are summarized in Table 1. In Table 1, the "incident surface" refers to the size of the incident surface onto which the LED light is incident. The "FWHM" refers to the full width at half maximum (FWHM) of the divergence angle of the LED light obtained by the ray tracing simulation. Regarding the uniformity of the emitted light, a flat and highly uniform illuminance distribution is indicated by ◎; a good illuminance distribution with a variation of less than 5% is indicated by ○; a variation of 5% to 10% is indicated by △; and a variation of 10% or more is indicated by ×.

[0062] [Table 1]

[0063] All examples in Table 1 relate to the light-guiding optical component of the first invention, and all comparative examples relate to the conventional tapered light tunnel. The size of the exit surface was standardized to 2.22 mm x 1.25 mm. Here, in the light-guiding optical component of the first invention, the incident section is a truncated quadrangular pyramid, and the four side surfaces of the truncated quadrangular pyramid are formed by CPC surfaces (i.e., a rectangular CPC; see FIG. 12). The length of the incident section was varied from 0.4 mm to 0.7 mm, and ray tracing simulations were performed with three sizes of the light-receiving incident surface: 0.3 mm x 0.3 mm, 0.4 mm x 0.4 mm, and 0.7 mm x 0.4 mm. In addition, ray tracing simulations were performed with the total length L of the light-guiding optical component being 1.5, 2, 3, 4, and 5 times the diagonal length D2 of the exit surface. On the other hand, for the tapered light tunnel, which is a conventional example, the overall length was set to match that of the light-guiding optical component of the first invention, with the longest length being six times the diagonal length of the exit surface, and the entrance surface sizes were set to three types: 0.3 mm x 0.3 mm, 0.7 mm x 0.4 mm, and 1.1 mm x 0.6 mm, and a ray tracing simulation was performed for a shape that uniformly tapered from the entrance surface to the exit surface.

[0064] The geometric model parameters for the light-guiding optical component of the first invention used in the ray tracing simulation are summarized in Table 2. The parameters include the total length L, tapered portion length L1, incident portion length L2, incident surface size H3xW3, and exit surface size H2xW2, as well as the angles β1 and β2 of the tapered portion with the horizontal and vertical directions. The term "rectangular CPC" appears in Table 2 and in Tables 5 and 6 below, and as mentioned above, this refers to a truncated quadrangular pyramid whose four side faces are all made up of CPC surfaces.

[0065] [Table 2]

[0066] For example, in Example 2, the total length L of the light-guiding optical component is 5.1 mm, which is twice the diagonal D2 of the exit surface opening, of which 0.5 mm is the length L2 of the incident portion and 4.6 mm is the length L1 of the tapered portion. The exit surface is 2.22 mm x 1.25 mm. The incident surface of the incident portion is 0.3 mm x 0.3 mm. The angle between the vertical surfaces of the tapered portion and the horizontal axis plane is 4.2°, and the angle between the widthwise side surfaces and the vertical axis plane is 10.0°.

[0067] Similarly, the geometric model parameters for the conventional tapered light tunnel for which a ray tracing simulation was performed are summarized in Table 3. The parameters include the ratio of the total length to the diagonal of the exit surface, the total length, the entrance surface size, the exit surface size, as well as the angles of the tapered portion with the horizontal and vertical directions.

[0068] [Table 3]

[0069] Among the examples shown in Table 1, five out of nine examples (Examples 2, 5, 7, 8, and 9) had extremely excellent uniformity of emitted light (◎). Three examples (Examples 1, 3, and 6) had uniformity variation of 5% or less (◯). Only one example (Example 4) had uniformity variation of 5% or more (△). On the other hand, simulations were performed on 18 examples of conventional tapered light tunnels listed as comparative examples. The only examples with excellent uniformity of irradiance distribution were those whose length was six times the diagonal angle of the emitting surface (Comparative Examples 16, 17, and 18). Of these, Comparative Example 18 had a large divergence angle. Among the other comparative examples, Comparative Example 9 and Comparative Example 12 had fair uniformity of irradiance distribution (variation within 5%), but both had large divergence angles of 25° or more. The other comparative examples had irradiance distribution variation of at least 5% or more.

[0070] FIG. 19 shows the results of a ray tracing simulation for Example 2 in Table 1. The illuminance distributions in the X-axis and Y-axis directions on the exit surface obtained from FIG. 19 are shown in FIGS. 20 and 21. Furthermore, FIG. 22 shows the distribution of radiance in angular space. In the radiance distribution diagram, the thick solid line represents the divergence angle distribution in the X direction, and the dashed-dotted line represents the divergence angle distribution in the Y direction. It can be seen that the shape of the light-guiding optical component of the present invention provides much more uniform illuminance distribution in both the X and Y directions than the tapered light tunnel with a truncated quadrangular pyramid shape shown later as a comparative example. Furthermore, the angular distribution of radiance revealed that when the light-guiding optical component of the present invention was used, the X-direction divergence angle (FWHM: full width at half maximum) was 13.35° and the Y-direction divergence angle (FWHM: full width at half maximum) was 16.97°, both within very narrow ranges.

[0071] Regarding the results of the examples of the present invention, in Example 1, whose length was only 1.5 times the diagonal angle of the exit surface, the divergence angle of the exit 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 approximately 3%. With an illuminance distribution of this level, the homogeneity was evaluated as good. Even in Example 3, whose incident length and incident surface were larger than those of Example 2, fluctuations of approximately 3% were observed in the X direction illuminance distribution, and in Example 4, a drop in illuminance of nearly 10% was observed in the center of the X direction illuminance distribution. Therefore, in the case where the total length was twice the diagonal angle of the exit surface, Examples 2 and 3 showed good results in all of the X direction illuminance distribution, Y direction illuminance distribution, and divergence angle.

[0072] As another example showing good results, the ray tracing simulation results (Fig. 23), X-direction illuminance distribution (Fig. 24), Y-direction illuminance distribution (Fig. 25), and divergence angle distribution (Fig. 26) for Example 7 in Table 1 are shown. The illuminance distribution is excellent in uniformity in both the X and Y directions. It was also found that the divergence angle of the radiance was narrowed to ±9.69° FWHM (full width at half maximum) in the X direction and 15.35° FWHM in the Y direction (height direction).

[0073] From the results of the examples of the present invention described above, and with reference to the results of the comparative examples, it was found that uniformity of the illuminance distribution and narrowing of the angle can be achieved when the total length L is 1.5 to 5 times the diagonal angle of the exit surface. Furthermore, from the results of the examples in Table 1 and Table 2, it was found that the appropriate taper angles of the tapered portions must be in the range of at least 1.9° to 5.8° for β1 and at least 4.1° to 13.8° for β2. Similarly, from the results of the examples in Table 1, it was found that the ratio L2 / L1 of the length L2 of the entrance portion to the length L1 of the tapered portion must be at least between 1 / 9 and 1 / 42. [Comparative Example]

[0074] For a conventional tapered light tunnel as a comparative example, a ray tracing simulation was performed (Fig. 27) for Comparative Example 4 in Table 1, and the X-direction illuminance distribution (Fig. 28) and Y-direction illuminance distribution (Fig. 29) were obtained. Although there were no problems with the Y-direction illuminance distribution, there were large drops in the X-direction illuminance distribution with variations exceeding 10% in two places, and it was found that the illuminance distribution could not be said to be uniform. The divergence angle was at a level where there were almost no problems.

[0075] Other results are summarized in Table 1. As described above, the X-direction illuminance distribution and the Y-direction illuminance distribution were evaluated as excellent in uniformity as in Examples 2 and 7, as well as O when the variation in uniformity was within 5%, △ when the variation in uniformity was 5% or more, and × when there were problems with uniformity as in Comparative Example 4. Regarding the divergence angle, a value of 15° or less is considered to have achieved narrowing of the angle, and a value of more than 20° can be evaluated as not having sufficiently narrowed the angle.

[0076] From the results in Table 1, among Comparative Examples 1 to 18, in which ray tracing simulations were performed on conventional tapered light tunnels, only Comparative Examples 16 and 17, which had lengths six times the diagonal of the exit surface and incident surface sizes of 0.3 x 0.3 mm and 0.7 x 0.4 mm, were able to achieve uniformity in illuminance distribution and a narrow angle. Comparative Example 15, which had a length five times the diagonal of the exit surface and an incident surface size of 1.1 x 0.6 mm, achieved uniformity in illuminance distribution, but the divergence angle reached nearly 30°, failing to achieve a narrow angle. The same can be said for Comparative Examples 9 and 12. In other words, it was found that with the conventional tapered light tunnels, uniformity in illuminance distribution and a narrow angle could not be achieved simultaneously unless the total length was six times the diagonal of the exit surface. [Example]

[0077] The light-guiding optical components of Example 2 of the present invention shown in Table 1 were arranged in five vertical rows and five horizontal rows without any gaps, resulting in a light-guiding optical component integrating five rows and five horizontal rows of light-guiding optical components. An LED element was then placed on the incident surface of each of the five rows and five horizontal rows of light-guiding optical components to obtain a surface-emitting lighting device. A ray-tracing simulation ( FIG. 30 ) was then performed to evaluate the illuminance distribution ( FIGS. 31 and 32 ) on the exit surface of the surface-emitting lighting device. Looking at the X-direction illuminance distribution and the Y-direction illuminance distribution, slight nonuniformity was observed due to the influence of stray light presumably from adjacent light-guiding optical components, as the light-guiding optical components were in contact with each other. It is believed that such nonuniformity can be avoided by arranging the light-guiding optical components with a spacing of approximately 0.1 mm to 0.3 mm. Furthermore, it is believed that by placing a condenser lens behind such a light source, the uniformity of light incident on the display device (light valve) of a projection-type display device will be at a completely unproblematic level. [Example]

[0078] Next, to examine the effect of the taper angle, we used Examples 2 and 4 in Table 1 as standard models to investigate the effects of the taper angle on the uniformity of the illuminance distribution and the divergence angle when the taper angle was widened to enlarge the exit surface and when the taper angle was narrowed to reduce the exit surface. The results are shown in Table 4. The parameters used in the simulation are shown in Table 5. The uniformity of the illuminance distribution significantly deteriorated when the taper angle of Example 2 was widened to enlarge the exit surface ( FIG. 33 ) and when the taper angle was narrowed to reduce the exit surface ( FIG. 34 ). The illuminance distribution also significantly deteriorated when the taper angle of Example 4 was widened to increase the exit surface. On the other hand, when the taper angle of Example 4 was narrowed to reduce the exit surface, the uniformity of the illuminance distribution improved somewhat, but the divergence angle became extremely large, and a narrower angle was not achieved. In this study, no taper angle was found that further improved the results of Examples 2 and 4 listed in Table 1.

[0079] [Table 4]

[0080] [Table 5]

[0081] Next, to investigate the effect of changing the length of the incident section on the illuminance distribution and divergence angle, simulations were performed using Example 2 in Table 1 as the standard model, with the incident section shortened (Example 15) and lengthened (Example 16). The simulation results are shown in Table 4, and the parameters used in the simulation are shown in Table 6. The uniformity (illuminance distribution) of the emitted light significantly deteriorated whether the incident section length was shortened or lengthened. When the length was shortened, the illuminance distribution in the X direction significantly increased near the center, and when the length was lengthened, the illuminance distribution in the X direction significantly decreased near the center. In other words, in this study, there was no incident section length longer than Example 2.

[0082] [Table 6] [Explanation of symbols]

[0083] 101 Square pillar light tunnel 102....Inlet surface of rectangular prism-shaped light tunnel 103....Exit surface of rectangular prism-shaped light tunnel 104...Side of rectangular pillar-shaped light tunnel 201 Tapered Light Tunnel 202....Tapered Light Tunnel Entrance Surface 203....Tapered light tunnel exit surface 204 Tapered Light Tunnel Side 301: An example of the light-guiding optical component of the present invention 302: Incident surface of an example of the light-guiding optical component of the present invention 303: Exit surface of an example of the light-guiding optical component of the present invention 304: Left and right side surfaces of the tapered portion of an example of the light-guiding optical component of the present invention 305: Upper and lower surfaces of the tapered portion of an example of the light-guiding optical component of the present invention 306: Upper surface of the tapered portion (also the bottom surface of the incident portion) of an example of the light-guiding optical component of the present invention 307: Upper surface of the incident portion of an example of the light-guiding optical component of the present invention 308: Side surface of the incident portion of an example of the light-guiding optical component of the present invention 309: An example of a lens portion of an example of the light-guiding optical component of the present invention 310: An example of an exit surface of a lens portion of an example of a light-guiding optical component of the present invention 701...LED light source 702···Condenser lens 703 Primary lens 704 Light valve 705...Reflector 706 Enlarged projection unit

Claims

1. Height H １ , width W １ Rectangle (H １ =W １ When the incident surface is square, the height H ２ , width W ２ The rectangular exit surface (H ２ >H １ , W ２ >W １ ) at an angle β in the height direction with respect to the optical axis １ , angle β in the width direction ２ a first truncated quadrangular pyramid having a solid tapered portion that widens in the direction of light propagation, and １ and width W １ The square or rectangle has a base of height H ３ , width W ３ Rectangle (H ３ =W ３ When the second square pyramid is a square, an entrance portion made of a second truncated quadrangular pyramid having an upper surface is formed continuously, and the second truncated quadrangular pyramid has a length L ２ and the angle β between the optical axis and any of the four side surfaces of the second truncated quadrangular pyramid is ３ is the above β １ and β ２ and the length L of the tapered portion １ and the length of the incident part L ２ The sum of (total length L) is the length D of the diagonal of the exit surface ２ The height L of the second truncated quadrangular pyramid is 1.5 times or more and 5 times or less. ２ is the length L of the tapered portion １ is in the range of 1 / 9 to 1 / 42 of the β １ is in the range of 1.9° to 5.8°, and the β ２ A light-guiding optical component characterized in that the angle is in the range of 4.1° to 13.8°.

2. Height a １ , width b １ Rectangle (a １ = b １ When the incident surface is square, the height H ２ , width W ２ β in the height direction relative to the optical axis toward the rectangular exit surface of ４ , β in the width direction ５ a solid tapered portion formed of a truncated quadrangular pyramid that widens toward the end, and １ , width b １ Rectangle (a １ = b １ The base is a square, and the minor axis a ２ , major axis b ２ The elliptical truncated cone is formed continuously with the ellipse as the upper surface, and the length of the elliptical truncated cone is L ３ and the angle β between the optical axis and the elliptical truncated cone at any position ６ is the above β ４ and β ５ and the length L of the tapered portion １ and the length L of the elliptical truncated cone ３ The sum of (total length L) is the length D of the diagonal of the exit surface ２ and the height L of the elliptical truncated cone is 1.5 times or more and 5 times or less. ３ is the length of the tapered part L １ is in the range of 1 / 9 to 1 / 42 of the β ４ is in the range of 1.9° to 5.8°, and the β ５ A light-guiding optical component characterized in that the angle is in the range of 4.1° to 13.8°.

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

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

5. A light-guiding optical component in which a plurality of light-guiding optical components according to claim 2 are arranged and integrated.

6. 6. An illumination device that emits light by bringing an LED optical element into contact with an incident surface of an incident portion of the light-guiding optical component according to claim 1, 2, 4 or 5.

7. 7. A projection display device comprising the lighting device according to claim 6, lens means, a light valve, a magnifying optical lens system, and a screen, wherein light from the LED elements that reaches the exit surface of the light-guiding optical component is condensed by the lens means to illuminate the light valve, and an output image generated by the light valve is magnified by the magnifying optical system and projected onto the screen.

Images