JPWO2008078820A1 - Integrator and optical unit using the same - Google Patents

Abstract

An integrator 21 that collects and guides incident light from a light source 11 as a surface light source having a uniform light intensity distribution in a specific range in a specific direction by a light guide having an incident surface 21a and an output surface 21b. Thus, the light guide has a light beam angle conversion means for converting the maximum outgoing light beam angle of the outgoing light to be smaller than the maximum incident light beam angle of the incident light with the area of the outgoing surface 21b being larger than the incident surface 21a. .

Description

  The present invention relates to an integrator that collects and guides incident light from a light source and emits it as a surface light source having a uniform light intensity distribution in a specific range in a specific direction. For example, an image or image is displayed on a screen using a liquid crystal panel. In particular, the present invention relates to a projector that is particularly effective when used in an optical unit such as a projector for projecting light.

  In an optical unit such as a projector, a system using an integrator as an illumination optical system is known. FIG. 13 shows the integrator type optical unit 101.

  An optical unit 101 shown in the figure is a projector, and includes a light source 11, a condenser reflector (reflector) 12, an integrator 31, a collimator lens 41, a liquid crystal plate 43 as an image conversion means, a projection optical system 45, and the like. Has been.

  In the figure, the light from the light source 11 is collected by the condenser reflector 12 and is incident on the incident surface 31 a of the integrator 31. The integrator 31 is configured by using a light guide made of a glass rod or the like having a rectangular cross section, and condenses and guides light incident from the incident surface 31a at one end while reflecting the light from the inner surface, and then from the exit surface 31b at the other end. Let it emit.

  Light emitted from the emission surface 31 b is irradiated on the image forming surface of the liquid crystal plate 43 after the parallelism is increased by the collimator lens 41. An image such as a moving image or a still image is drawn on the liquid crystal plate 43 by light transmission control in units of pixels by an image signal. By irradiating the image forming surface of the liquid crystal plate 43 uniformly from the back, a transmitted light image obtained from the front surface is imaged on the screen 47 by the projection optical system 45, so that the drawn image on the liquid crystal plate 43 is The image can be enlarged and projected on the screen 47.

  In the integrator-type illumination optical system described above, by reducing the rod cross-sectional area of the light guide forming the integrator 31 or increasing the length thereof, the illumination light that illuminates the illuminated area such as a liquid crystal plate It is said that the in-plane light intensity distribution can be made uniform (see, for example, Patent Document 1).

  In the illumination optical system described above, a light guide having a uniform cross-sectional area, a so-called straight rod, is used as the integrator 31. However, as shown in FIG. There is also provided an illumination optical system using, as an integrator 32, a light guide so-called tapered rod having a larger area of the exit surface 32b than the entrance surface 32a (see, for example, Patent Document 2).

  FIG. 14 shows an integrator-type optical unit 101 using the taper rod. Focusing on the difference from FIG. 13, in the optical unit 101 shown in FIG. 14, by using a tapered rod for the integrator 32, the emission angle of the emitted light can be made smaller than when a straight rod is used. .

  Thereby, the quality of the illumination light irradiated to the liquid crystal plate 43 can be improved, and the display quality of the image (video or still image) can be improved. Further, the optical characteristics required for the subsequent optical system such as the collimator lens 41 installed in order to increase the parallelism of the emitted light can be made relatively gradual, for example, by reducing the number of lenses.

  As described above, conventionally, a straight rod or taper rod is used to collect and guide incident light from a light source and emit it as a surface light source with a uniform light intensity distribution in a specific range in a specific direction. In this way, an optical unit such as a projector is configured.

JP 2002-90883 A Japanese Patent Laid-Open No. 2004-70095

  However, the above-described conventional technique has the following problems.

  That is, the integrators 31 and 32 described above are incident surfaces 32a on the incident side of the integrator 32 in an illumination optical system such as a projector, even when a tapered rod capable of making the outgoing angle of outgoing light smaller than that of a straight rod is used. In order to condense the light from the light source 11 and efficiently enter the light, it is necessary to use a large condensing reflection 12. Further, on the output side of the integrator 32, there has been a need to use a collimating optical system such as the collimating lens 41 in order to uniformly irradiate the output light from the output surface 32b to a specific range.

  The emitted light from the integrators 31 and 32 has an emission angle that is not constant and has a certain degree of variation distribution. For this reason, when the emitted light is used as illumination light for the liquid crystal plate 43 or the like, light emitted at an angle exceeding a predetermined allowable range cannot be used as image light. As a result, there arises a problem that the illumination efficiency of the illumination optical system deteriorates. In order to avoid this problem, a collimating optical system is absolutely necessary in the above-described conventional technology.

  In an illumination optical system such as a projector, it is necessary to create illumination light suitable for obtaining a high-quality transmitted light image (or reflected light image) by irradiating a liquid crystal plate or the like. For this purpose, it is required that the entire image forming surface such as a liquid crystal plate can be illuminated with a uniform light intensity distribution.

  That is, in an illumination system such as a projector, when incident light from a light source is collected and guided and emitted as a surface light source having a uniform light intensity distribution to a specific range in a specific direction, for example, an image forming area of a liquid crystal plate, In addition to the direction uniformity of the emitted light, illumination light having a good uniformity of light intensity distribution is indispensable for obtaining a good quality transmitted light image (or reflected light image). If the uniformity of the light intensity distribution is poor, the quality of the projected image is lowered. In particular, in the projection of a color image, the influence is likely to appear conspicuously in color unevenness, contrast reduction, and color tone reproduction.

  The present invention solves the above-described problems, and its purpose is to use a large condensing reflector for making light incident from a light source and a collimating optical system for improving the direction uniformity of emitted light. High light utilization efficiency can be ensured without the need to reduce the size and cost of the entire illumination system such as a projector. Furthermore, when illuminating an illumination target such as a liquid crystal plate, It is an object of the present invention to provide an integrator that improves the uniformity of the light intensity distribution in the image and enables high-quality image reproduction without color unevenness.

  Other objects and configurations of the present invention will become apparent from the description of the present specification and the accompanying drawings.

As means for solving the above problems, the present invention provides the following means.
(1) An integrator that collects and guides incident light from a light source and emits it as a surface light source having a uniform light intensity distribution in a specific range in a specific direction,
The integrator is a light guide having an exit surface area larger than that of the incident surface, and a light beam angle conversion means for converting the maximum outgoing light beam angle of the outgoing light smaller than the maximum incident light beam angle of the incident light is formed. An integrator characterized by

(2) An integrator of the above means (1),
The integrator is a light guide having a hollow structure having a reflecting mirror surface inside a cavity, wherein the area of the opening on the exit surface is larger than the opening on the entrance surface.

(3) An integrator of the above means (1),
The integrator is a solid-state light guide made of a solid optical member having a light incident side end surface that forms the light incident surface and a light output side end surface that forms the light output surface, and the surface area of the light incident surface is the surface area of the light incident surface. An integrator having a total reflection surface which is formed to be equal to or larger than the opening area and which forms the light beam angle conversion means inside the light guide path between the light incident side end surface and the light output side end surface. .

(4) An integrator of the above means (3),
The above integrator is characterized in that the outer surface is subjected to specular reflection processing or optical boundary surface total reflection processing so that the inside of the light guide path excluding part or all of the input / output surfaces is made the total reflection surface. Integrator.

(5) An integrator of the above means (1) to (4),
The reflection surface forming the light beam angle conversion means is inclined with respect to the light guide direction of the light guide, and the light guide cross-sectional area at the half length of the light guide is not cut off at the entrance surface. An integrator characterized by being larger than half of the sum of the area and the cross-sectional area at the exit surface.

(6) An integrator of the above means (1) to (5),
The light guide cross-sectional area of the light guide increases from the incident surface portion toward the output surface portion by tilting the reflection surface forming the light beam angle conversion means with respect to the light guide direction of the light guide, and The light guide cross-sectional area at an arbitrary position of the light guide is the same or larger over the entire length than the light guide cross-sectional area at the corresponding position of the simple tapered light guide having the same input / output area and length. Integrator.

(7) An integrator of the above means (1) to (6),
The light guide cross-section of the light guide is rectangular, the inner four side surfaces of the light guide are aspherical, and the inner reflection surface forms the light angle conversion means. An integrator characterized by that.

(8) An integrator of the above means (1) to (7),
The light guide cross-section of the light guide is rectangular, and the light guide cross-sectional area spreads while the reflecting surfaces on the four inner sides thereof are inclined at a predetermined aspheric coefficient toward the exit surface. A featured integrator.

(9) An integrator of the above means (1) to (8),
An integrator characterized in that a cross-sectional shape of a light incident side of the light guide is similar to the shape of a light emitting light source and is the same as or larger than the light emitting light source.

(10) The integrator of the above means (1) and (3) to (9),
An integrator according to claim 1, wherein an incident surface of the light guide is concave.

(11) An integrator of the above means (1) to (10),
The cross-sectional shape of the emission surface portion is similar to the shape of the image conversion means that is arranged in the light emission direction of the emission surface and transmits or reflects the emitted light to form an image, and the cross-sectional area of the image conversion means An integrator characterized by being equal to or larger than the image area.

  (12) An optical unit using the integrator of the above means (1) to (11).

(13) The optical unit of the means (12),
The above-mentioned means (1) to (11) for emitting a light source of a plurality of colors that are primary colors or complementary colors, and a surface light source having a uniform light intensity distribution in a specific range while converting incident light from the light sources of the respective colors, respectively. An optical unit comprising: an integrator of the above; and a color synthesis optical system that superimposes outgoing light of each color in the same range.

  (14) The optical unit according to (13), wherein the color synthesis optical system is configured by using a cross prism.

  (15) The optical unit according to the above means (13), wherein the color synthesizing optical system is configured by using a dichroic mirror.

  In a lighting system such as a projector, it is possible to ensure high light use efficiency without using a large condensing reflector for making light incident from a light source and a collimating optical system for improving the direction uniformity of emitted light. This makes it possible to reduce the size and cost of the entire illumination system such as a projector. Further, when illuminating an illumination target such as a liquid crystal plate, the uniformity of the light intensity distribution within a specific range is improved to prevent color unevenness. It is possible to provide an integrator and an optical unit that enable high-quality image reproduction without any problem.

 Other operations / effects of the present invention will become apparent from the description of the present specification and the accompanying drawings.

  FIG. 1 shows a first embodiment of an integrator 21 and an optical unit 100 to which the technology of the present invention is applied. In the same figure, (a) is a schematic sectional view of the entire optical unit 100 including the illumination system, and (b) shows a section at each position (A, B, C) of the integrator 21.

  First, the optical unit 100 shown in FIG. 1A is a projector, and includes a light source 11, an integrator 21, a liquid crystal plate 43 as an image conversion means, a projection optical system 45, and the like.

  In the drawing, an LED (light emitting diode) is used as the light source 11 and is installed close to the incident surface 21 a of the integrator 21. The light from the light source 11 is directly incident on the incident surface 21 a of the integrator 21.

  The integrator 21 condenses and guides the light from the light source 11 and emits it as a surface light source having a uniform light intensity distribution in a specific range in a specific direction, and is from a solid optical member such as glass or plastic. It is comprised by the light guide of the solid structure which becomes.

  The light incident on the integrator 21 is guided while being reflected in the integrator 21 and is emitted from the emission surface 21b. The emitted light is applied to the image forming surface of the liquid crystal plate 43. An image such as a moving image or a still image is drawn on the liquid crystal plate 43 by light transmission control in units of pixels by an image signal.

  A transmitted light image obtained from the front surface by uniformly irradiating the image forming surface of the liquid crystal plate 43 from behind is formed on the screen 47 by the projection optical system 45, thereby drawing an image on the liquid crystal plate 43. Is enlarged and projected on the screen 47.

  In addition, the liquid crystal plate has a reflection type that draws an image such as a moving image or a still image by light reflection control in units of pixels. However, when using this, light is incident obliquely on the liquid crystal plate and the reflection is performed. An optical image is incident on the projection optical system, or a polarization beam splitter (PBS) is inserted between the outgoing light and the reflective liquid crystal, and the reflected optical image from the liquid crystal is turned 90 degrees on the screen by the projection optical system. What is necessary is just to form an image.

  The integrator 21, which is a light guide, has an incident surface 21a at one end and an exit surface 21b at the other end. On the inner side of the light guide path excluding the entrance surface 21a and the exit surface 21b, a total reflection surface that performs specular reflection is formed. The total reflection surface is formed by specular reflection processing on the outer surface by metal vapor deposition or the like or total reflection processing on the optical boundary surface.

  Here, the integrator 21 of this embodiment is formed in a rectangular cross-section having reflection surfaces on four side surfaces, has a larger cross-sectional area at the exit surface 21b portion than the entrance surface 21a portion, and has four side surfaces. Each reflecting surface is formed such that the light guide cross-sectional area is expanded while being inclined at a predetermined aspheric coefficient toward the exit surface 21b.

  The reflection surface formed on the inner side of the light guide path excluding the entrance / exit surfaces 21a and 21b of the integrator 21 is inclined with respect to the light guide direction and guided at a half length portion (C position) of the whole length of the integrator 21. The optical cross-sectional area is formed to be larger than half the sum of the cross-sectional area at the incident surface portion (A position) and the cross-sectional area at the output surface portion (B position).

  The reflection surface in the integrator 21 is formed in an aspheric taper shape such that the angle with respect to the light guide axis (center axis in the light guide direction) zo gradually decreases according to the length position of the integrator 21.

  In the integrator 21, as shown in FIG. 2, light incident at a high angle with respect to the light guide axis zo is reflected at a large inclination angle close to the incident surface 21a. As a result, the angle of the reflected light L11 with respect to the light guide axis zo is significantly lower than the incident angle.

  On the other hand, light incident at a relatively low angle with respect to the light guide axis zo is reflected when the inclination angle is relatively small apart from the incident surface 21a. As a result, the angle of the reflected light L13 with respect to the light guide axis zo is lower than the incident angle, but the degree is smaller than in the above case.

  In this way, the light incident on the integrator 21 is guided with a greater angle conversion as the incident angle increases. That is, the integrator 21 is provided with a light beam angle conversion function that converts the maximum outgoing light beam angle of the outgoing light smaller than the maximum incident light beam angle of the incident light.

  By such a light beam angle conversion function, even if light having a wide angle with respect to the light guide axis zo is incident on the incident surface 21a, light whose angle with respect to the light guide axis zo is reduced from the output surface 21b. A lot of light comes out. In other words, incident light with a wide angle can be introduced from the incident surface 21a, while outgoing light with a suppressed angular spread can be obtained from the output surface 21b.

  As a result, the light can be efficiently collected and guided without a large condensing reflector for allowing light to enter from the light source, and the emitted light can be reflected without installing a collimating optical system. Directional uniformity can be improved. This is very effective for reducing the size and cost of the entire illumination system such as a projector while ensuring high light utilization efficiency.

  Further, in the integrator, the light beam angle conversion function can obtain the effect of improving the uniformity of the light intensity distribution in addition to improving the direction uniformity of the emitted light.

  FIG. 3 shows the light guide state of the integrator 21 having the light angle conversion function together with that of the conventional simple tapered integrator 32.

  As shown in the figure, the aspherical tapered integrator 21 has an aspherical inclination in which the inclination of the taper is large on the incident side and becomes gentler toward the emission side. On the other hand, the simple tapered integrator 32 has a constant inclination over the entire length.

  In the aspherical tapered integrator 21, the light guide cross-sectional area increases from the incident surface 21 a toward the exit surface 21 b, and the light guide cross-sectional area at an arbitrary position of the integrator 21 has an input / output area and It is larger over the entire length than the light guide cross-sectional area at the corresponding position of the simple tapered light guide having the same length h.

  When light Li from the same direction is incident on the aspherical taper integrator 21 and the simple taper integrator 32, the incident light Li is guided and emitted while reflecting inside the integrators 21 and 32. Each of the light guide states has the following characteristics.

  That is, at least for the light reflected at a position closer to the incident side than the middle in the length direction of the aspherical taper integrator 21, the inclination angle of the reflection surface at the reflection position with respect to the horizontal direction (light guide axis zo direction) is compared. The reflection angle (angle formed by the incident optical axis and the reflected optical axis) is large due to the large size. For this reason, the arrival distance of the primary reflected light there becomes longer than that of the simple taper integrator 32.

  However, for secondary reflected light reflected at a position close to the reflection side beyond the center of the length, the angle of inclination with respect to the horizontal direction of the reflecting surface at the reflection position becomes smaller, so that the reflection angle is reversed. Becomes smaller. For this reason, the reach distance of the secondary reflected light is shorter than that of the simple taper integrator 32.

  As a result, the aspheric taper integrator 21 has a higher probability of reflecting the secondary reflected light once more. By increasing the reflection probability, the light intensity distribution in the predetermined range of the emitted light is made uniform. As a result, the aspherical taper integrator 21 can obtain outgoing light having a more uniform light intensity distribution than the simple taper integrator 32.

  The aspheric taper integrator 21 can arbitrarily design the directionality of the emitted light and the state of the light intensity distribution according to the change state of the taper inclination angle with respect to the aspheric coefficient of the taper, that is, the length. That is, the controllability for optimizing the directionality of the emitted light and the light intensity distribution according to the application is good.

  FIG. 4A shows a computer simulation result of the state of condensing and guiding the incident light beam by the aspheric taper integrator 21. Moreover, (b) of the same figure shows the computer simulation result of the light intensity distribution pattern of the emitted light from the integrator 21.

  FIG. 5A shows an illuminance distribution graph by the light emitted from the aspherical taper integrator 21, and FIG. 5B shows an illuminance distribution graph by the light emitted from the simple taper integrator 32.

  As illustrated in FIGS. 4 and 5, the aspherical taper integrator 21 according to the present invention is better in both the directionality of the emitted light and the light intensity distribution state than that of the simple taper integrator 32.

  As described above, the integrator 21 in the above embodiment uses a large condensing reflecting mirror for making light incident from a light source and a collimating optical system for improving the direction uniformity of emitted light in an illumination system such as a projector. Even if it is not, it is possible to ensure high light use efficiency, and this makes it possible to reduce the size and cost of the entire illumination system such as a projector. Furthermore, when illuminating an illumination target such as a liquid crystal plate, the uniformity of the light intensity distribution within a specific range can be improved, and high-quality image reproduction without color unevenness can be achieved.

  In the embodiment of the integrator, as shown in FIG. 1B, the light emitting surface of the light source 11 and the liquid crystal plate 43 serving as image conversion means are used for the cross-sectional shapes of the incident surface 21a and the exit surface 21b, respectively. Are formed in a rectangle having the same aspect ratio.

  The cross-sectional shape of the incident surface 21 a is similar to the shape of the light emitting light source 11 and is larger than the light emitting light source 11. Thereby, the ratio of the light which injects into the entrance plane 21a can be raised.

  The cross-sectional shape of the exit surface 21b is similar to the shape of the image forming surface of the liquid crystal plate 43 constituting the image converting means, and the cross-sectional area is formed to be equal to or larger than the image area of the image converting means. Thereby, the emitted light can be irradiated onto the image forming surface of the liquid crystal plate 43 without excess or deficiency, and the light utilization efficiency can be further increased.

  The integrator 21 has a rectangular light guide cross section, and the inner four side surfaces of the light guide are formed in an aspherical shape. In this case as well, the reflection surface of the four side surfaces is the maximum incident ray angle of incident light. Light beam angle conversion means for converting the light beam to a smaller maximum light beam angle is formed.

  On the inner side of the light guide path excluding the entrance surface 21a and the exit surface 21b of the integrator 21, a total reflection surface for specular reflection is formed. This total reflection surface is a specular reflection process on the outer surface by metal deposition or the like. It can be formed by total reflection processing of the optical boundary surface by coating with an optical material having a refractive index difference. Specifically, a metal vapor deposition film such as Al, Ag, Au, or a dielectric multilayer coating is used.

  FIG. 6 exemplarily illustrates the behavior of incident light in the vicinity of the incident surfaces 21 a and 32 a of the aspherical taper integrator 21 and the simple taper integrator 32.

  As shown in the figure, the light L2 incident on the incident surface 32a of the simple taper integrator 32 at a large angle (steep angle) is incident on the reflecting surface in the integrator 32 at an angle close to perpendicular. For this reason, in the simple taper integrator 32, there is a high probability that the light L2 incident at a large angle passes through the side surface of the integrator 32 without being reflected, and the light amount loss tends to increase. This loss of light amount becomes a problem particularly on a total reflection surface using a difference in refractive index, for example.

  However, in the aspheric taper integrator 21, the closer the incident side is, the steeper the inclination of the reflecting surface, so that the light L1 incident on the incident surface 21a at a large angle is also low on the steeply reflecting surface. By being incident at an angle, the light is reliably reflected and condensed and guided. Thereby, even on the total reflection surface using the difference in refractive index, it is possible to efficiently collect and guide the incident light L1 while suppressing the light amount loss.

(Example)
In the integrator 21 and the optical unit 100 shown in FIG. 1, the light source 11 is an InGaN-based LED having a light distribution of 1.5 mm × 2.5 mm at a distance of 0.4 mm from the light emitting surface.

  The light beam emitted from the LED could be efficiently incident on the integrator 21 having an aspheric side surface with an incident end shape of 1.7 mm × 2.8 mm at a distance of 0.4 mm from the light emitting surface.

  The integrator 21 is obtained by processing a resin for an optical member by an injection molding method using a mold whose side shape is designed to be aspheric by a predetermined aspheric coefficient. Tables 1 to 4 show examples of the aspheric coefficients.

The light is guided to the exit end while being repeatedly reflected in the integrator 21, but the light beam emitted from the exit end can be a light flux whose light quantity is uniformed and whose spread is controlled (see FIG. 4).

  The emission end face shape is a rectangular cross-sectional shape having a diagonal ratio of 3: 3 and a diagonal length of 13 mm with respect to a diagonal 1/2 inch aspect ratio 4: 3 of the rectangular panel-shaped liquid crystal plate 45 located behind the integrator 21. The light emitted from the integrator 21 was irradiated to the liquid crystal plate 45 almost entirely without passing through the condenser lens.

  When the amount of light emitted from the aspherical integrator 21 was compared with that of the simple taper integrator 32, it was confirmed that the amount of light emitted by the aspherical taper integrator 21 was 7% higher than that of the simple taper integrator 32.

  Regarding the uniformity of the light intensity distribution, the integrator 21 having a side shape whose cross-sectional size is determined by the aspheric order in Table 1 is distributed 1.5 mm × 2.5 mm at a distance of 0.4 mm from the light emitting surface. Light from an InGaN-based RGB three-color LED having a light distribution was incident, and the amount of light was measured by scanning the Si detector vertically and horizontally at a portion 10 mm from the output end of the integrator. Then, the amount of light in the vertical direction was integrated, and the distribution in the horizontal direction was plotted.

  As a result, as shown in part in FIG. 5, it was confirmed that the uniformity of the light intensity distribution is greatly improved in the aspheric integrator 21.

Tables 1 to 4 exemplify the aspheric coefficients of the integrators used for each color of R (Red), G (Green), and B (Blue), respectively, where X is the length of the light guide (X = 0). , 0 is the incident surface position), H + and H- are horizontal distances from the light guide center axis, and V + and V- are vertical distances from the light guide center axis.

  FIG. 7 shows a second embodiment of the integrator 21 and the optical unit 100 to which the technology of the present invention is applied.

  Paying attention to the difference from the first embodiment described above, in the second embodiment shown in the figure, the incident surface 21a of the integrator 21 is formed in a concave shape.

  The integrator 21 is usually configured using an optical material such as glass or resin. The light incident on the integrator 21 is refracted in accordance with the difference ratio between the light refractive index n1 before incidence and the light refractive index n2 after incidence, so that the light beam direction in the integrator 21 changes.

  Here, as shown in FIG. 8A, when the incident surface 21a of the integrator 21 is a plane perpendicular to the light guide axis, the light incident at an angle θ1 with respect to the light guide axis is After entering the integrator 21, it travels through the integrator 21 at a refraction angle θ2 smaller than the incident angle θ.

  Thus, when the incident surface 21a of the integrator 21 is flat, the light incident on the integrator 21 is refracted with reference to the light guide axis perpendicular to the incident surface 21a, and the traveling direction is bent inward. For this reason, the reflection opportunity in the integrator 21 decreases. If this reflection opportunity is reduced, the effect of improving the uniformity of the light intensity distribution of the emitted light is impaired.

  On the other hand, in the integrator 21 in which the incident surface 21a is formed in a concave shape, the incident light to the incident surface 21a is based on the normal of the incident surface at the incident point, as shown in FIG. Is refracted. For this reason, the light incident on the integrator 21 at the incident angle θ1 with respect to the normal line enters the integrator 21 at the refraction angle θ2 (θ1> θ2), and the refraction angle θ2 is the incident surface at the incident point. Since it is based on the normal, it will bend outward and proceed.

  Thereby, the reflection opportunity in the integrator 21 increases, and the effect of further improving the uniformity of the light intensity distribution of the emitted light can be obtained.

  FIG. 9 shows a computer simulation result of the state of condensing and guiding the incident light by the integrator 21 having the incident surface 21a formed in a concave shape. Moreover, (b) of the same figure shows the computer simulation result of the light intensity distribution pattern of the emitted light from the integrator 21. As shown in the figure, it was confirmed that the effect of further improving the uniformity of the light intensity distribution of the emitted light can be obtained by forming the incident surface 21a in a concave shape.

  FIG. 10 shows a first embodiment of a color optical unit 110 using the aspheric integrator 21.

  The optical unit 110 shown in the figure includes an RGB color illumination system, and includes three light sources 11R, 11G, and 11B that emit three primary colors of RGB (red, green, and blue) for each color, and light sources 11R, 11G, and The three integrators 21R, 21G, and 21B that emit incident light (R, G, and B) from 11B as surface light sources having a uniform light intensity distribution in a specific range while converting the light beam angles, respectively, and outgoing light for each color ( A color synthesizing optical system for superimposing R, G, B) in the same range is provided. These are assembled and installed in a single casing 50.

  The color synthesizing optical system is configured by using one cross prism 52 and two reflecting prisms 51 and 53.

  The R-color light and B-color light emitted from the integrators 21R, 21B are reflected by the reflecting prisms 51, 53 in a right angle direction and are incident on both side surfaces of the cross prism 52. The cross prism 52 combines the G color light emitted from the integrator 21G with the R color light and the B color light. The three-color composite light (RGB) is irradiated on the image forming surface of the liquid crystal plate 43.

  Color images such as moving images and still images are drawn on the liquid crystal plate 43 by light transmission control in units of pixels (pixels) based on image signals. A transmitted light image obtained from the front surface by uniformly irradiating the image forming surface of the liquid crystal plate 43 from the back is formed on the screen 47 by the projection optical system 45, whereby color drawing on the liquid crystal plate 43 is performed. The image is enlarged and projected on the screen 47.

  FIG. 11 shows a second embodiment of a color optical unit 110 using the aspheric integrator 21. Focusing on the difference from the above embodiment, in this embodiment, the color synthesis optical system is configured by using one reflection prism 54 and two dichroic prisms 55 and 56.

  The R color light emitted from the integrator 21 </ b> R is reflected by the prism 54 in a right angle direction and is incident on the first dichroic prism 55. The first dichroic prism 55 includes a prism and an optical multilayer film, and waits for a color separation function to selectively transmit light in the R wavelength region and selectively reflect light in the G wavelength region. It has been. The first dichroic prism 55 creates combined light of R color and G color, and enters the second dichroic prism 56.

  The second dichroic prism 56 is allowed to wait for a color separation function that selectively reflects light in the R and G wavelength regions and selectively transmits light in the B wavelength region. The second dichroic prism 56 superimposes the RG synthesized light incident from the first dichroic prism 55 on the B color light emitted from the integrator 21B to create RGB synthesized light, and irradiates the liquid crystal plate 43 with it.

  FIG. 12 shows a third embodiment of the color optical unit 110 using the aspheric integrator 21. Focusing on the difference from the above embodiment, in this embodiment, the color synthesis optical system is configured by using one total reflection mirror 57 and two dichroic mirrors 58 and 59.

  The R color light emitted from the integrator 21 </ b> R is reflected by the total reflection mirror 57 in the right angle direction and is incident on the first dichroic mirror 58. The first dichroic mirror 58 is composed of a transparent plate such as optical glass or plastic and an optical multilayer film, and selectively transmits light in the R wavelength region and selectively transmits light in the G wavelength region. Waiting for the color separation function to be reflected. The first dichroic mirror 58 creates combined light of R and G colors and makes it incident on the second dichroic mirror 59.

  The second dichroic mirror 59 is allowed to wait for a color separation function that selectively reflects light in the R and G wavelength regions and selectively transmits light in the B wavelength region. The second dichroic mirror 59 superimposes the RG synthesized light incident from the first dichroic mirror 58 on the B color light emitted from the integrator 21B to create RGB synthesized light, and irradiates the liquid crystal plate 43 with it.

The color optical unit 110 of the third embodiment is advantageous in terms of weight reduction and cost reduction by not using a prism.
In addition, this optical system does not contain image information in the incoming / outgoing light of the light combiner, so it is usually possible to use unusable plastic for the substrate because of poor surface accuracy. And lower costs.

  As described above, the present invention has been described based on the typical embodiments. However, the present invention can have various modes other than those described above. For example, the integrator 21 of the present invention may have a cross section other than a rectangle, and may have a circular, elliptical or other cross sectional shape depending on the application.

  In a lighting system such as a projector, it is possible to ensure high light use efficiency without using a large condensing reflector for making light incident from a light source and a collimating optical system for improving the direction uniformity of emitted light. As a result, it is possible to reduce the size and cost of the entire illumination system such as a projector. It is possible to provide an integrator and an optical unit that enable high-quality image reproduction without any problem.

It is the schematic which shows 1st Embodiment of the integrator and optical unit to which the technique of this invention was applied. It is a figure which shows and modeled the operation | movement of the integrator which concerns on this invention. It is a figure which shows and modeled the operation | movement of the integrator which concerns on this invention. It is a figure which simulates the characteristic of the integrator by 1st Embodiment of this invention with a computer, and shows it. It is a graph which shows the light intensity distribution state of the integrator which concerns on this invention, and the conventional integrator. It is a figure which shows the behavior of the incident light in the vicinity of the entrance plane of the integrator which concerns on this invention, and the conventional integrator. It is the schematic which shows 2nd Embodiment of the integrator and optical unit to which the technique of this invention was applied. It is a consideration reference figure for demonstrating the characteristic of the integrator by 2nd Embodiment of this invention. It is a figure which simulates the characteristic of the integrator by 2nd Embodiment of this invention with a computer, and shows it. It is the schematic which shows 1st Embodiment of the color optical unit using the integrator of this invention. It is the schematic which shows 2nd Embodiment of the color optical unit using the integrator of this invention. It is the schematic which shows 3rd Embodiment of the color optical unit using the integrator of this invention. It is the schematic which shows the 1st structural example of the conventional integrator and optical unit. It is the schematic which shows the 2nd structural example of the conventional integrator and optical unit.

Explanation of symbols

100 Optical unit (present invention)
101 Optical unit (conventional)
110 Color optical unit (present invention)
11 Light source 11R R color light source 11G G color light source 11B B color light source 12 Condensing reflector (reflector)
21R R color integrator 21G G color integrator 21B B color integrator 21 Integrator (present invention)
21a Incident surface 21b Outgoing surface 31 Integrator (straight rod)
31a entrance surface 31b exit surface 32 simple tapered integrator 32a entrance surface 32b exit surface 41 collimating lens 43 liquid crystal plate 45 projection optical system 47 screen 51, 53 reflection prism 52 cross prism 54 reflection prism 55 dichroic prism 56 dichroic prism 57 total reflection mirror 58 Dichroic mirror 59 Dichroic mirror zo Light guide axis (center axis in the light guide direction)

Claims (15)

An integrator that collects and guides incident light from a light source and emits it as a surface light source with a uniform light intensity distribution in a specific range in a specific direction,
The integrator is a light guide having an exit surface area larger than that of the incident surface, and a light beam angle conversion means for converting the maximum outgoing light beam angle of the outgoing light smaller than the maximum incident light beam angle of the incident light is formed. An integrator characterized by The integrator according to claim 1,
The integrator is a light guide having a hollow structure having a reflecting mirror surface inside a cavity, wherein the area of the opening on the exit surface is larger than the opening on the entrance surface. The integrator according to claim 1,
The integrator is a solid-state light guide made of a solid optical member having a light incident side end surface that forms the light incident surface and a light output side end surface that forms the light output surface, and the surface area of the light incident surface is the surface area of the light incident surface. An integrator having a total reflection surface which is formed to be equal to or larger than the opening area and which forms the light beam angle conversion means inside the light guide path between the light incident side end surface and the light output side end surface. . An integrator according to claim 3,
The above integrator is characterized in that the outer surface is subjected to specular reflection processing or optical boundary surface total reflection processing so that the inside of the light guide path excluding part or all of the input / output surfaces is made the total reflection surface. Integrator. The integrator according to claim 1, wherein
The reflection surface forming the light beam angle conversion means is inclined with respect to the light guide direction of the light guide, and the light guide cross-sectional area at the half length of the light guide is not cut off at the entrance surface. An integrator characterized by being larger than half of the sum of the area and the cross-sectional area at the exit surface. The integrator according to claim 1,
The light guide cross-sectional area of the light guide increases from the incident surface portion toward the output surface portion by tilting the reflection surface forming the light beam angle conversion means with respect to the light guide direction of the light guide, and The light guide cross-sectional area at an arbitrary position of the light guide is the same or larger over the entire length than the light guide cross-sectional area at the corresponding position of the simple tapered light guide having the same input / output area and length. Integrator. The integrator according to claim 1, wherein
The light guide cross-section of the light guide is rectangular, the inner four side surfaces of the light guide are aspherical, and the inner reflection surface forms the light angle conversion means. An integrator characterized by that. The integrator according to claim 1,
The light guide cross-section of the light guide is rectangular, and the light guide cross-sectional area spreads while the reflecting surfaces on the four inner sides thereof are inclined at a predetermined aspheric coefficient toward the exit surface. A featured integrator. The integrator according to claim 1, wherein
An integrator characterized in that a cross-sectional shape of a light incident side of the light guide is similar to the shape of a light emitting light source and is the same as or larger than the light emitting light source. An integrator according to claims 1 and 3-9,
An integrator according to claim 1, wherein an incident surface of the light guide is concave. The integrator according to claim 1, wherein
The cross-sectional shape of the emission surface portion is similar to the shape of the image conversion means that is arranged in the light emission direction of the emission surface and transmits or reflects the emitted light to form an image, and the cross-sectional area of the image conversion means An integrator characterized by being equal to or larger than the image area.   An optical unit using the integrator according to claim 1. The optical unit according to claim 12,
The integrator according to any one of claims 1 to 11, wherein a plurality of color light sources that are primary colors or complementary colors and incident light from the light sources of each color are emitted as surface light sources having a uniform light intensity distribution in a specific range while converting the light beam angle. And a color synthesizing optical system that superimposes outgoing light of each color in the same range.   14. The optical unit according to claim 13, wherein the color combining optical system is configured using a cross prism. 14. The optical unit according to claim 13, wherein the color combining optical system is configured using a dichroic mirror.