JP2007121602A - Illumination optical system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination optical system, capable of adjusting to luminance with which a display image is made more visible, without adversely affecting the reliability, the lifetime, and so on of a light source, when the illumination optical system is used in the illuminating device of an image display device and without causing degradations in the contrast and color reproducibility of a display image and nonuniform luminance and nonuniform color. <P>SOLUTION: The illumination optical system includes a fly-eye integrator comprising a first fly-eye lens array 5 and a second fly-eye lens array 6, and a superposition lens 7. In the illumination optical system, the superposition lens 7 is set operable so as to move along an optical axis, and the distance of the superposition lens 7 with respect to the second fry-eye lens array 6 is made adjustable. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an illumination optical system for illuminating an object to be illuminated such as a spatial light modulator by guiding a light beam from a light source in an image display device or the like.

  2. Description of the Related Art Conventionally, there has been proposed an image display device that includes a plurality of spatial light modulation elements, illuminates these spatial light modulation elements with an illumination device, and forms an image of illumination light modulated through each spatial light modulation element. ing. The illumination device in such an image display device includes a light source and an illumination optical system that guides a light beam from the light source and illuminates the spatial light modulation element.

  An ultra-high pressure mercury lamp or the like is used as a light source in the illumination device. As the illumination optical system, an illumination optical system having an integrator such as a fly-eye integrator made up of a pair of fly-eye lens arrays is used in order to equalize the brightness of the light beam from the light source and guide it to the spatial light modulator.

  In such an image display device, when viewing a display image in a bright room, the illumination light that illuminates the spatial light modulation element is set to a high brightness, while when viewing a display image in a dark room, It is necessary to reduce the luminance of the illumination light that illuminates the light modulation element and adjust the luminance so that the displayed image is easy to see.

  As means for adjusting the luminance of illumination light for illuminating the spatial light modulation element, conventionally, the output of a lamp, which is a light source of an illumination device, is adjusted via a lamp power supply. That is, it is a means for adjusting the brightness of the illumination light by adjusting the amount of current supplied to the lamp to adjust the output of the lamp. Further, as means for adjusting the luminance of the illumination light without adjusting the output of the lamp, the entrance pupil in the illumination optical system is stopped and the F number of the illumination optical system is adjusted.

  Further, as a means for adjusting the luminance of the display image without adjusting the luminance of the illumination light, a projection optical system using a variable aperture of a projection optical system (projection lens) that forms an image of the illumination light that has passed through the spatial light modulation element is used. The F number of the system is adjusted.

  In Patent Document 1, the illumination efficiency for the spatial light modulation element by the light flux from the light source is improved by moving and adjusting one of the fly-eye lens arrays forming the fly-eye integrator in a direction orthogonal to the optical axis. The configuration is described. This is intended to improve the illumination efficiency and increase the brightness of the illumination light by matching the illumination range by the illumination optical system with the position of the spatial light modulator, and adjust the brightness of the illumination light. It does not present a means to do.

JP-A-10-115803

  By the way, in the image display apparatus as described above, when adjusting the luminance of the illumination light by adjusting the output of the light source (lamp), there is a problem of adversely affecting the reliability and life of the light source.

  That is, in a lamp such as an ultra-high pressure mercury lamp used as a light source, a temperature condition for stable light emission, a bulb internal pressure condition, and the like are set. There is a risk of deviating from this condition. If the lamp is used in a state deviating from these appropriate temperature conditions, bulb internal pressure conditions, etc., there is a problem that reliability, life, etc. are impaired.

  Further, in the image display device, the brightness of the display image is adjusted by adjusting the F number of the illumination optical system by narrowing the entrance pupil in the illumination optical system, or by adjusting the F number of the projection optical system by the variable diaphragm of the projection optical system. In such a case, there has been a problem in that contrast degradation, color reproducibility degradation, luminance unevenness or color unevenness is caused in the display image.

  That is, in the image display device, the light that has passed through the reflective spatial light modulation element is separated into polarization-modulated light and light that has not been polarization-modulated by a polarization optical element such as a polarization beam splitter, and converted into intensity modulation. ing. Further, in the image display device, spectral optical elements such as a dichroic mirror and a dichroic prism are used for color separation and color synthesis of each color light of R (red), G (green), and B (blue). Such a polarizing optical element and a spectroscopic optical element have an incident angle dependency with respect to the polarization separation characteristic and the spectral characteristic, and when the incident angle is out of a predetermined angle range, the predetermined polarization separation characteristic or spectral characteristic is obtained. There is a possibility that the characteristics cannot be exhibited. Therefore, when the F number of the illumination optical system or the projection optical system changes, the incident angle distribution of the incident light beam with respect to the polarization optical element or the spectroscopic optical element changes, and the contrast or color reproducibility in the display image deteriorates, or the luminance. There was a problem that unevenness and color unevenness were invited.

  The present invention has been made in view of the above points. When used in an illumination device of an image display device, the present invention does not adversely affect the reliability and life of the light source, and contrast and color reproducibility in a display image. It is an object of the present invention to provide an illumination optical system that can adjust the brightness of a display image so that the display image can be easily seen without causing deterioration of the brightness, uneven brightness, or uneven color.

In order to solve the above-mentioned problems, the present invention comprises means described in the following 1) to 2).
That is,
1) a first fly-eye lens array into which a light beam from a light source is incident; a second fly-eye lens array into which a light beam that has passed through the first fly-eye lens array is incident; and a superimposing lens, In an illumination optical system that illuminates an object to be illuminated at a position substantially conjugate with respect to the first fly-eye lens array by the superimposing lens with the light beam that has passed through the second fly-eye lens array,
An illuminating optical system comprising adjusting means for adjusting a light beam for illuminating the object to be illuminated by enabling the superimposing lens to be moved along an optical axis.
2) An integrator having a columnar region in which a light beam from a light source is incident from one end side and is reflected from the inner surface and is emitted from the other end side, and a superimposing lens. In an illumination optical system that illuminates an illumination object,
An illuminating optical system comprising adjusting means for adjusting a light beam for illuminating the object to be illuminated by enabling the superimposing lens to be moved along an optical axis.

  In the present invention, in the illumination optical system provided with the fly-eye lens array integrator, the superimposing lens can be moved along the optical axis, and the distance to the second fly-eye lens array can be adjusted. Since the imaging magnification of the first fly-eye lens array having a conjugate relationship with the object to be illuminated can be adjusted, and the size of the illumination area can be changed to adjust the amount of light flux per unit area. The brightness of the illumination light can be adjusted without changing the F number.

  The adjustment range of the position of the superimposing lens may be about 10 mm in the optical axis direction. Such position adjustment can be realized only by adding a simple adjustment mechanism.

  The present invention also provides illumination optics including an integrator having a columnar region in which a light beam from a light source is incident from one end side and is reflected from the inner surface and emitted from the other end side, such as a rod integrator, a light pipe, and a light tube. In the system, the superimposing lens can be moved along the optical axis, and the distance to the object to be illuminated can be adjusted, thereby adjusting the luminance of the illumination light without changing the F number as the optical system. be able to.

  That is, the present invention, when used in an illuminating device of an image display device, does not adversely affect the reliability, life, etc. of the light source, and deteriorates contrast and color reproducibility, luminance unevenness and color unevenness in the display image. Therefore, it is possible to provide an illumination optical system that can adjust the display image to a brightness that allows easy viewing.

  The best mode for carrying out the invention of the illumination optical system according to the present invention will be described below with reference to preferred embodiments.

  First, a general integrator optical system will be described as an illumination optical system used in an illumination device of an image display device.

  An illumination optical system in an illumination device of an image display device needs to efficiently collect a light beam emitted from a lamp serving as a light source on a spatial light modulation element serving as a front object. Therefore, in such an illumination optical system, systems roughly classified into two systems, “critical illumination” and “Keller illumination”, are used.

  FIG. 1 is a perspective view for explaining the principle of critical illumination.

  As shown in FIG. 1, critical illumination is an illumination optical system that forms an image of a light source 1 on an object to be illuminated (spatial light modulation element) 3 by a condenser lens 2. The light source 1 and the object to be illuminated 3 are in a conjugate relationship.

  In this illumination optical system, since the image of the light source 1 is formed on the object 3 to be illuminated, it is possible to illuminate with very high luminance, while the light source image is formed on the object 3 to be illuminated. Illumination unevenness due to distribution (shape of light emitter) is likely to occur.

  FIG. 2 is a perspective view for explaining the principle of Keller illumination.

  As shown in FIG. 2, Keller illumination is an illumination optical system in which a relay lens 4 as an aperture stop is arranged between a light source 1 and an object to be illuminated 3 and an image of the aperture stop is formed on the object to be illuminated 3. is there. The light source 1 and the relay lens 4 have a conjugate relationship, and the condenser lens 2 and the object to be illuminated 3 have a conjugate relationship. This illumination optical system can be said to be an illumination optical system conceived for solving the above-mentioned problems of critical illumination.

  Illumination light on the object to be illuminated 3 in Keller illumination has a relatively uniform illuminance distribution. However, when the object to be illuminated 3 is rectangular, if the relay lens 4 as the aperture stop is circular, an image of the aperture stop is formed, resulting in poor illumination efficiency. Further, when a discharge lamp (HID lamp) is used as the light source, there is a problem that the convection of the gas in the lamp bulb and the change of the bright spot appear as fluctuations on the illuminated object 3.

  The illumination optical system according to the present invention is an extension of Keller illumination, and a matrix of 50 to 100 rectangular lenses (cells) similar to the illumination area in order to eliminate luminance fluctuations on the object 3 to be illuminated. This is an integrator illumination optical system in which a large number of pseudo-Keller illumination systems are superimposed on the object to be illuminated 3 using a pair of fly-eye lens arrays arranged in a shape.

  FIG. 3 is a perspective view for explaining the principle of the illumination optical system according to the present invention.

  As shown in FIG. 3, the illumination optical system according to the present invention includes a first fly-eye lens array 5 which is disposed on the light source 1 side and into which a light beam from the light source 1 is incident, and the first fly-eye lens array. 5 and a second fly-eye lens array 6 on which the light beam having passed through 5 is incident. Each cell (rectangular lens) constituting the second fly-eye lens array 6 corresponds to an open stop (relay lens 4) in Keller illumination, and has a conjugate relationship with the light source 1. Each cell (rectangular lens) constituting the first fly's eye lens array 5 has a conjugate relationship with the object 3 to be illuminated. That is, a conjugate image of each cell of the first fly-eye lens array 5 by each cell of the second fly-eye lens array 6 is an illumination area on the illumination object 3. The images of the cells of the first fly-eye lens array 5 are superimposed on the object 3 by the superimposing lens 7. Therefore, illumination with a uniform illuminance distribution and high efficiency is performed on the object 3 to be illuminated.

  Here, since the second fly-eye lens array 6 corresponds to an aperture stop in the illumination optical system, the F number of the illumination optical system is determined by the aperture of each cell of the second fly-eye lens array 6 and the superimposing lens 7. And the focal length f. Further, the second fly-eye lens array 6 is an aperture stop between the first fly-eye lens array 5 and the object to be illuminated 3 that are in a conjugate relationship. Therefore, the image of the aperture stop is an image of the light source 1.

  FIG. 4 is a side view showing a light source image formed on the second fly-eye lens array 6.

  As described above, the illumination optical system according to the present invention is an integrator optical system and can be said to be an assembly of Keller illumination. Considering a set of Keller illuminations, as shown in FIG. 4A, the lens surface A on the first fly-eye lens array 5 has an illumination area A on the object 3 to be conjugated. The image is magnified to '. At this time, considering the efficiency with which the light from the light source 1 is used for illumination, the light from the light source 1 is condensed on the lens B of the second fly-eye lens array 6 that is an aperture stop by the lens surface A. When it is done, it becomes the most efficient.

On the other hand, the illumination area on the object to be illuminated 3 is in a conjugate relationship with the lens surface A, so that an optical system that forms an image of the lens surface A on the object to be illuminated 3 as shown in FIG. , The magnification β of the illumination area A ′ has the following relationship according to Newen's formula.
β = A ′ / A = S ′ / S
However, S is the distance from the lens surface A to the lens B, and S ′ is the distance from the lens B to the illumination area A ′ (illuminated object 3). Here, S and S ′ are the distance from the lens surface A to the object side main surface of the lens B and the distance from the image side main surface of the lens B to the illumination area A ′, respectively.

  Here, although the lens surface A is a lens, it is a lens for condensing a light beam, and does not contribute anything to the imaging relationship of the lens surface A with respect to the illumination area A ′. When the distance between the lens A surface and the lens B (the distance between the first fly-eye lens array 5 and the second fly-eye lens array 6) is changed, S in the above equation is changed. When S is decreased, the imaging magnification β is increased. Conversely, when S is increased, the imaging magnification β is decreased.

  FIG. 5 is a side view showing the configuration of the illumination optical system according to the first embodiment of the present invention.

  In this illumination optical system, a discharge lamp such as an ultra-high pressure mercury lamp is used as the light source 1, and a light beam emitted from this lamp is converted into substantially parallel light by the paraboloid reflector 8 to the first fly eye integrator 5. Make it incident. The light beam that has passed through the first fly-eye lens array 5 is condensed on each of the opposing cells of the second fly-eye lens array 6.

  Then, the light beam transmitted through the second fly-eye lens array 6 is incident on the PBS array 9. This PBS array 9 is a PS synthesis prism, which separates the non-polarized light transmitted through the second fly-eye lens array 6 into a P-polarized component and an S-polarized component, and a λ / 2 plate (a half-wave plate). By converting the S-polarized component into the P-polarized component (or converting the P-polarized component into the S-polarized component), the optical element aligns the polarization direction of the illumination light in a fixed direction.

  The light beam that has passed through the PBS array 9 is condensed by the superimposing lens 7 onto the illumination area on the spatial light modulation element that becomes the object to be illuminated 3. The shape of the light beam condensed in the illumination area is a similar image to each cell of the first fly-eye lens array 5, and the images of all the cells are superimposed. The brightness of the display image and the uniformity of the in-plane brightness in the image display device are determined by the state of light collection in the illumination area.

  In this illumination optical system, as shown by an arrow A in FIG. 5, the superimposing lens 7 can be moved along the optical axis, and the distance to the PBS array 9 can be adjusted. Various mechanisms such as a cam mechanism can be used as the mechanism for moving the superimposing lens 7 in the optical axis direction.

  FIG. 6 is a side view showing a state before and after moving the superimposing lens 7 in the illumination optical system according to the present invention.

  FIG. 7 is a front view showing a change in the illumination area due to the movement of the superimposing lens 7 in the illumination optical system according to the present invention.

  Then, from the state shown in FIG. 6 (a), as shown in FIG. 6 (b), in this illumination optical system, the superimposing lens 7 is moved along the optical axis toward the PBS array 9. Then, as shown in FIG. 7, the imaging magnification in the illumination area of the first fly-eye lens array 5 increases. Then, the light flux amount (luminance) per unit area becomes small and the illumination light becomes dark. At this time, since the position and aperture of the second fly-eye lens array 6 that is an aperture stop do not change, the F number as the illumination optical system does not change.

  FIG. 8 is a graph showing the relationship between the movement of the superimposing lens 7 and the luminance in the illumination area in the illumination optical system according to the present invention.

  As described above, in this illumination optical system, the superimposing lens 7 is moved along the optical axis and the distance to the PBS array 9 is adjusted, so that the F number as the optical system is not changed, and the light source Without changing the output of 1, it is possible to change the luminance in the illumination area as shown in FIG. It should be noted that a moving amount of the superimposing lens 7 is practically about 10 mm.

  In order to configure an image display device using an illumination device having this illumination optical system, an image of a spatial light modulation element illuminated by the illumination device is displayed on a screen by a projection optical system (projection lens) (not shown). And zoom in on the image. At this time, when the spatial light modulation element is an element that performs polarization modulation, the polarization-modulated component and the non-polarization-modulated component of the illumination light that has passed through the spatial light modulation element are converted into a polarization beam splitter. The light is separated by a polarization separation element, and only the polarization-modulated component is guided to the projection optical system.

  Furthermore, in order to construct an image display device for displaying a color image, the luminous flux from the light source is color-separated by a spectroscopic element such as a dichroic mirror or a dichroic prism, and an R (red) illumination optical system and a spatial light modulator , G (green) illumination optical system and spatial light modulation element, B (blue) illumination optical system and spatial light modulation element are each made incident with monochromatic light, and modulated through each spatial light modulation element. Is synthesized by a spectroscopic element such as a dichroic prism and guided to the projection optical system. Then, an image of each spatial light modulation element is enlarged and formed on the screen by the projection optical system.

  FIG. 9 is a side view showing the configuration of the illumination optical system according to the second embodiment of the present invention.

  As shown in FIG. 9, in the illumination optical system according to the second embodiment, a light beam from a light source 1 such as a rod integrator, a light pipe, or a light tube is incident from one end side. It can also be configured as an illumination optical system that includes a columnar integrator 10 having a columnar region that emits light, and that illuminates the illuminated object 3 with a light beam that has passed through the columnar integrator 10.

  In an illuminating device using this illumination optical system, a discharge lamp such as an ultra-high pressure mercury lamp is used as the light source 1, and a light beam emitted from this lamp is made into substantially parallel light by a paraboloid reflector 8, and a condenser lens 11. Then, the light is condensed and made incident on one end side of the columnar integrator 10. The light beam incident on the columnar integrator 10 is multiple-reflected on the inner surface of the columnar integrator 10 to make the luminance distribution uniform, and is emitted from the other end side of the columnar integrator 10. The light beam emitted from the column integrator 10 is condensed by the superimposing lens 7 onto the illumination area on the spatial light modulation element that becomes the illumination object 3.

  FIG. 10 is a cross-sectional view illustrating a configuration of a rod integrator that is a columnar integrator.

  As shown in FIG. 10, the columnar integrator 10 can be configured as a rod integrator. The rod integrator is integrally formed of a transparent material into a prismatic shape having a rectangular cross-sectional shape that is similar to the illumination area. In this rod integrator, a light beam incident at a small incident angle from one end side passes through this rod integrator and reaches the other end side, and a light beam incident at a large incident angle from one end side is Internal reflection is repeated at the side surface to reach the other end. In this way, by condensing the luminous flux that has been repeatedly reflected internally in the rod integrator onto the illumination area on the spatial light modulator by the superimposing lens 7, the luminance in the illumination area is made uniform.

  FIG. 11 is a cross-sectional view showing a configuration of a light pipe (light tube) which is a columnar integrator.

  Moreover, the columnar integrator 10 can be configured as a light pipe (light tube) as shown in FIG. The light pipe (light tube) is formed in a hollow cylindrical shape, and the cross-sectional shape of the hollow portion is a rectangle that is similar to the illumination area. In this light pipe (light tube), a light beam incident at a small incident angle from one end side passes through the light pipe (light tube) and reaches the other end side, and is incident at a large incident angle from one end side. The luminous flux is repeatedly reflected on the inner surface of each side wall of the light pipe (light tube) and reaches the other end. Thus, by condensing the luminous flux repeatedly reflected in the light pipe (light tube) onto the illumination area on the spatial light modulation element by the superimposing lens 7, the luminance in the illumination area is made uniform.

  As shown by an arrow B in FIG. 9, the superimposing lens 7 can be moved along the optical axis, and the distance to the object to be illuminated 3 can be adjusted. Various mechanisms such as a cam mechanism can be used as the mechanism for moving the superimposing lens 7 in the optical axis direction.

  Also in this illumination optical system, by operating the superimposing lens 7 to move along the optical axis and adjusting the distance to the object 3 to be illuminated, as the illumination optical system in the first embodiment, as an optical system, The brightness of the illumination light can be adjusted without changing the F number of the light source and without changing the output of the light source 1.

It is a perspective view explaining the principle of the critical illumination used as an illumination optical system of an illuminating device. It is a perspective view explaining the principle of Keller illumination used as an illumination optical system of an illuminating device. It is a perspective view explaining the principle of the illumination optical system which concerns on invention. In the said illumination optical system, it is a side view which shows the light source image formed on the 2nd fly eye lens array. It is a side view which shows the structure in the 1st Example of the said illumination optical system. It is a side view which shows the state before and behind moving operation of a superimposition lens in the said illumination optical system. It is a front view which shows the change of the illumination area | region by the movement of a superimposition lens in the said illumination optical system. It is a graph which shows the relationship between the superimposition lens in the said illumination optical system, and the brightness | luminance in an illumination area | region. It is a side view which shows the structure in the 2nd Example of the illumination optical system which concerns on this invention. It is sectional drawing which shows the structure of the rod integrator which is a columnar integrator in the said illumination optical system. It is sectional drawing which shows the structure of the light pipe (light tube) which is a columnar integrator in the said illumination optical system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Condenser lens 3 Illuminated object 5 1st fly eye lens array 6 2nd fly eye lens array 7 Superimposition lens 10 Column-shaped integrator

Claims (2)

A first fly-eye lens array into which a light beam from a light source is incident; a second fly-eye lens array into which a light beam that has passed through the first fly-eye lens array is incident; and a superimposing lens. In the illumination optical system for illuminating an object to be illuminated at a position substantially conjugate with respect to the first fly-eye lens array by the superimposing lens with the light beam that has passed through the fly-eye lens array of
An illuminating optical system comprising adjusting means for adjusting a light beam for illuminating the object to be illuminated by enabling the superimposing lens to be moved along an optical axis. A light beam from a light source is incident from one end side, and includes an integrator having a columnar region that reflects the light beam from the other side and exits from the other end side, and a superimposing lens. The light beam that has passed through the integrator is illuminated by the superimposing lens. In the illumination optical system that illuminates
An illuminating optical system comprising adjusting means for adjusting a light beam for illuminating the object to be illuminated by allowing the superimposing lens to be moved along the optical axis.

Images