JP2005258469A - Lighting unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a bright image display by effectively using illumination light emitted by a light source. <P>SOLUTION: A lighting unit is equipped with a lighting optical system having a rod integrator 26 which makes the light intensity distribution uniform in luminous flux emitted by a light source 27 having a reflector 16 having a curvedly formed reflecting surface reflecting light emitted by light emission part 12 and lens systems 30 and 20 which project luminous flux emitted by the rod integrator 26 as illumination light, a 1st reflecting element 6 which is arranged to reflect unnecessary light, unused as illumination light, of the luminous flux projected from the lighting optical system toward the light source 27, and a 2nd reflecting element 14 which is provided with an opening part that the luminous flux from the light source 27 passes through and is arranged on one end side where the luminous flux from the light source 27 of the rod integrator 26 is made incident to reflect the unnecessary light which is reflected by the 1st reflecting element 6 and passes through the rod integrator 26 to the lens system side through the rod integrator 26. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an illuminating device, and more particularly to an illuminating device used for a projection-type image display device.

  2. Description of the Related Art Conventionally, there has been proposed a projection type image display device that includes an illumination device, a modulation element illuminated by the illumination device, and a projection lens that forms an image of the modulation element. Such an image display device has been put to practical use as a relatively large image display device using a discharge lamp as a light source of an illumination device and using liquid crystal as a modulation element.

  In such an image display device, the cost of the device can be reduced by adopting a structure in which a color filter is arranged in each pixel of one modulation element and a so-called sequential color display method for performing color display in a time division manner. However, there is a problem that light utilization efficiency is low and power consumption is large.

  The reason why the light use efficiency is low is that the modulation element is a non-light-emitting element that modulates the polarization state of incident light, so a means for separating the light beam emitted from the light source by the polarization component and then synthesizing it is necessary. Unlike the display device, the light source emits light even in black display, and there is a loss corresponding to the light use efficiency determined by the aperture ratio of the modulation element.

  In order to solve such problems, there has been proposed one described in JP-A-6-281814 (Patent Document 1).

JP-A-6-281814

  By the way, in the conventionally proposed lighting device, the manufacturing process is complicated, the manufacturing is complicated, and the cost is high.

  Moreover, in order to obtain the contrast necessary for the image display device, the illumination device described in Patent Document 1 needs to be used in combination with an absorption-type polarizing plate (polarizing plate that absorbs the other polarized light). It was difficult to improve the light utilization efficiency.

  Therefore, the present invention is proposed in view of the above-described circumstances, and intends to provide an illuminating device that improves the use efficiency of illuminating light without causing a complicated configuration and a complicated manufacturing. It is.

  In order to solve the above-described problem, an illumination device according to the present invention includes a light source having a light emitting unit and a reflecting mirror having a curved reflecting surface that reflects light emitted from the light emitting unit, and the light source emits light from the light source. An illumination optical system having a rod integrator that equalizes the light intensity distribution in the emitted light beam, a lens system that emits the light beam emitted from the rod integrator as illumination light, and the light beam emitted from the illumination optical system. The light source of the rod integrator is provided with a first reflecting element disposed so as to reflect unnecessary light that is not used as illumination light to the light source side, and an opening that transmits a light beam from the light source. Is disposed on one end side where the light beam from the incident light is incident, is reflected by the first reflecting element, reflects the unnecessary light transmitted through the rod integrator, and A second reflective element for reflecting to the lens system side through the integrator.

  In the illumination device according to the present invention, a condenser lens is disposed between a relay lens and a field lens constituting a lens system that emits the illumination light of the rod integrator, and light of an optical system from the light source to the rod integrator. The optical axis of the optical system after the condenser lens is shifted in parallel with respect to the axis, and the unnecessary light reflected by the first reflective element is moved to the light source side of the condenser lens on the first reflective element side. A further reflecting element that reflects the light is provided.

  In the illumination device according to the present invention, unnecessary light is reflected to the light source side by the first reflecting element and can be used as illumination light, so that the utilization efficiency of illumination light is improved.

  Embodiments of the present invention will be described below with reference to the drawings.

[Outline of general lighting equipment]
Prior to the description of the present invention, a general lighting device in an image display device using a modulation element that modulates the polarization state will be described. As shown in FIG. 1, the illumination device includes a light source 1, an integrator element 2, a polarization conversion element 3, and a condenser lens group 4. The illumination light emitted from the illumination device enters the modulation element 5. In addition, a color separation element may be disposed between the polarization conversion element 3 and the modulation element 5 in order to correspond to a modulation element corresponding to the display of the three primary colors (R, G, B).

  The integrator element 2 averages the unevenness of the light intensity distribution in the light beam emitted from the light source 1. The polarization conversion element 3 is an element having a function of separating and synthesizing a light beam emitted from the light source 1 according to a polarization component. The condenser lens group 4 is an element for efficiently causing the light beam emitted from the integrator element 3 to enter the modulation element 5. The condenser lens group 4 is a lens that forms an image of the integrator element 2 on the modulation element 5.

[Outline of lighting device]
An illumination device according to the present invention modulates a first reflecting element that reflects unwanted light that does not illuminate a modulation element among light beams emitted from a light source to the light source side, and a light beam reflected by the first reflecting element. And a second reflecting element that reflects toward the element side. With these reflecting elements, unnecessary light can be reused as illumination light, and the display image can be brightened without increasing the light emission intensity of the light source itself.

  Such an illuminating device in which unnecessary light can be reused as illuminating light is referred to as a “recyclable illuminating device” in the following description. In the present invention, an image display device as shown below can be configured by using this “recycle type lighting device”.

(1) Image display device provided with polarization type recycling illumination device (2) Image display device provided with illumination device that effectively improves aperture ratio of modulation element (3) High-efficiency single plate color image display device (4) High-efficiency sequential color image display device (5) Image display device with improved peak luminance Each lighting device used in these image devices will be described later.

[Basic type of recyclable lighting equipment]
As shown in FIG. 2, the recycle type illumination device includes an illumination optical system including a light source 1, an integrator element 2, a polarization conversion element (not shown), and a condenser lens group 4, and further includes a first reflection element 6. ing. Here, the light source 1 uses a discharge lamp provided with a parabolic mirror 7 which is a rotating parabolic reflecting mirror. The light emitting point of the discharge lamp as the light emitting unit is located at the focal point of the parabolic mirror 7. The integrator element 2 is shown as a fly-eye integrator having a first fly-eye lens surface 8 and a second fly-eye lens surface 9. A polarization conversion element (not shown) is disposed after the integrator element 2. The condenser lens group 4 is shown as comprising a condenser lens 10 and a field lens 11. Here, the first reflecting element 6 is shown as a plane mirror perpendicular to the optical axis.

  In the following description, the light beam reaching the first reflecting element 6 from the light source 1 is referred to as primary light, and the light beam after being reflected by the first reflecting element 6 is referred to as recycled light. In FIG. 2, a representative light beam of the primary light is indicated by a solid line, and recycled light corresponding to the primary light is indicated by a broken line.

  That is, the primary light emitted from the light emitting point of the discharge lamp located at the focal point of the parabolic mirror 7 is reflected by the parabolic mirror 7 to become a parallel light flux, and the first fly eye lens surface of the fly eye integrator. 8 is incident perpendicularly. The primary light is converged for each divided element of the first fly-eye lens surface 8 and condensed on each divided element of the second fly-eye lens surface 9. That is, the light source image of the primary light is formed on each divided element of the second fly-eye lens surface 9. The primary light passes through the second fly-eye lens surface 9 and the condenser lens group 4 and reaches the first reflecting element 6. This illumination optical system is a telecentric optical system in which the principal ray is parallel to the optical axis at the position of the first reflecting element 6.

  Here, each divided element of the first fly-eye lens surface 8 and the first reflecting element 6 have a conjugate relationship. The second fly's eye lens surface 9 and the light emitting point of the light source 1 are in a conjugate relationship, and the corresponding dividing element of the first fly's eye lens surface 8 has a diaphragm action.

  Then, the recycled light reflected by the first reflecting element 6 returns to the fly eye integrator element 2. Of this recycled light, the light beam that has passed through the range where the primary light has passed through the second fly-eye lens surface 9 and has passed through the corresponding first fly-eye lens surface 8 is coupled to the light emitting point. Image.

  Actually, since the size of the parabolic mirror 7 is finite and the glass bulb forming the light source 1 is a shielding object, there exists recycled light that is shielded in the process of returning to the light emitting point.

[Lighting equipment that improves recycling efficiency]
In the illuminating device used for the image display device according to the present invention, as shown in FIG. 3, the first reflecting element 6 is inclined with respect to the optical axis, and the reflecting plate 14 serving as the second reflecting element is provided. This improves the recycling efficiency of illumination light. The illumination device has an illumination optical system including a light source 1, an integrator element 2, a polarization conversion element (not shown), and a condenser lens group 4, and further includes a first reflection element 6. Here, the light source 1 is shown as a discharge lamp provided with an elliptical mirror 16 that is a reflecting mirror of a spheroidal surface, and the light emitting point is located on the first focal point of the elliptical mirror 16. The condenser lens group 4 includes two lenses, a condenser lens (relay lens) 10 and a field lens 11.

  At the second focal position of the elliptical mirror 16, a reflecting plate 14 that also serves as a stop is disposed. The reflecting plate 14 is made of a material having high reflectivity, and has an opening pattern corresponding to a light beam emitted from the second fly-eye lens surface 9 of the integrator element 2 for each divided element.

  The image side focal length of the condenser lens 10 is set to be in the vicinity of the field lens 11. This illumination optical system is a telecentric optical system in which the principal ray is parallel to the optical axis at the position of the first reflecting element 6. In this illumination optical system, the recycled light reflected by the first reflecting element 6 returns to a position deviated from the opening pattern of the reflecting plate 14 because the first reflecting element 6 is inclined with respect to the optical axis. The reflection plate 14 reflects the light. The recycled light reflected by the reflecting plate 14 returns to the first reflecting element 6 again. In FIG. 3, a representative light beam of the primary light is indicated by a solid line, and a recycling path is indicated by a broken line.

  As shown in FIG. 4, this illuminating device may be configured by shifting the optical axis of the optical system after the condenser lens 10 in parallel by an appropriate amount. Here, the appropriate amount for shifting the optical axis is about 1/4 of the element division pitch in the fly-eye integrator 2. Also in FIG. 4, a representative light beam of the primary light is indicated by a solid line, and a recycling path is indicated by a broken line.

  In the illumination devices shown in FIGS. 3 and 4, the opening diameter of the reflector 14 is generally determined by the etendue of the object to be illuminated, but is determined in consideration of the aspect ratio of the object to be illuminated and the recycling efficiency.

  The positions of the second flyer eye lens surface 9 and the reflecting plate 14 are substantially conjugate positions. That is, the recycled light reflected by the first reflecting element 6 forms an illuminance distribution different from the illuminance distribution of the primary light on the second fly-eye lens surface 9, and the illuminance pattern of each element is the reflector 14. It is superimposed on the position of. For example, if each element shape of the second fly-eye lens surface 9 is the same rectangular shape, the illuminance pattern on the reflection plate 14 of the recycled light is a rectangular shape in which the illuminance at the central opening corresponding to each element shape is low. It becomes.

  Further, the pattern of the reflected light from the first reflecting element 6 forms a similar pattern in each divided element of the first fly-eye lens surface 8. When the first fly's eye lens surface 8 and the image side focal position of the condenser lens group 4 coincide with each other, when the first fly's eye lens surface 8 is reached again, it returns to a symmetrical position with respect to the optical axis. In the case where the configuration of the first fly-eye lens surface 8 is a symmetrical layout with respect to the optical axis, a symmetrical pattern of the reflection pattern is formed on each divided element of the first fly-eye lens surface 8, and again The first reflective element 6 is illuminated without making the illuminance uniform. For the purpose of making the illuminance uniform, it is better to leave a gap between the field lens 11 and the first fly-eye lens surface 8. Since the light rays other than the principal ray do not have a symmetrical relationship at the position of the first fly-eye lens surface 8, the illuminance of the recycled light can be made uniform.

  As shown in FIG. 5, the illuminating device according to the present invention is disposed near the light source 1 having the elliptical mirror 16, the relay lens 20 disposed on the second focal point of the elliptical mirror 16, and the relay lens 20. When the reflector 14, the field lens 21, the reflective polarizing plate 19, the fly eye integrator 2, the condenser lens 10, the field lens 11 and the first reflective element 6 are sequentially arranged, the optical system after the condenser lens 10 is arranged. These optical axes can be shifted in parallel.

  The reflecting plate 14 has an opening at the center and functions as a diaphragm for the relay lens 20.

  In this illumination device, the recycled light reflected by the reflective polarizing plate 19 returns to the light emitting point of the light source 1 through the field lens 21, the relay lens 20, and the elliptical mirror 16. The recycled light reflected by the first reflecting element 6 is reflected by the reflecting plate 14 and returns to the first reflecting element 6 again. Also in FIG. 5, a representative light beam of the primary light is indicated by a solid line, and a recycling path is indicated by a broken line.

[About the first reflective element]
The first reflective element does not necessarily have to be added with a special element as the first reflective element. That is, an element that originally exists to reflect unnecessary light for another purpose can be used as the first reflecting element. Examples of the element that can be the first reflective element include a reflective polarizing plate, a polarizing beam splitter, a light shielding layer, a reflective layer of a reflective modulation element, and a reflective color filter. Specific arrangement will be described later.

[Requirements for improving recycling efficiency]
The requirements for improving the recycling efficiency of the illumination light include the following four requirements.
(1) The relationship between the first reflective element and the integrator is an optical conjugate point.
(2) The surface reflection of the members constituting the lighting device should be as small as possible.
(3) A structure for efficiently reflecting the return light is provided.
(4) The modulation element has an etendue that allows the etendue of the light source to increase during the recycling process.

  The first requirement is as described above.

  In order to satisfy the second requirement, it is necessary to apply an antireflection film to each optical component and to reduce the number of reflecting surfaces by integrating components that can be integrated. For example, it is desirable that an antireflection film is also applied to the glass surface constituting the discharge bulb. In FIG. 2, the PS conversion element, the condenser lens 10, and the second fly-eye lens surface 9 of the fly-eye integrator are optically brought into close contact with each other.

  The third requirement will be described later.

  The fourth requirement “Etendue of the modulation element” is expressed by the product of the illumination area illuminated by the modulation element and the solid angle of the illumination light. On the other hand, “Etendue of the light source” is expressed by the product of the emission area and the solid solid angle of the emitted light. For example, in a light source composed of a parabolic mirror and a discharge bulb, the “light source etendue” is the product of the area of the opening of the parabolic mirror and the radiant solid angle of the emitted light at that position. In the process of returning unnecessary light to the light source side and reflecting it again to the modulation element side, the etendue of the light source increases. When the etendue of the modulation element is relatively small compared to the etendue of the light source, the recycled light illuminates a range larger than the intended illumination range, and the recycling efficiency decreases.

[Configuration of light source to improve recycling efficiency (1)]
As described above, when the light source includes a parabolic mirror, the recycled light is completely at the same position and angle as the primary light when the unnecessary light returns to the opening of the parabolic mirror. It does not match. Further, the recycled light does not return to the light emitting point of the light source even when there is a deviation in the alignment of the optical element in manufacturing. As a structure in which this point is improved, as shown in FIG. 6, in a light source provided with a parabolic mirror 7, a surface 13b of a protective glass (face plate) 13 provided at the opening end of the parabolic mirror 7 is used. Alternatively, it is conceivable to add reflecting plates 14a and 14b serving as second reflecting elements to the back surface 13a. The reflecting plates 14a and 14b are located at the central portion and the peripheral portion of the protective glass 13, and may be provided by forming a thin film or a dielectric multilayer film made of a metal material such as aluminum or silver on the protective glass 13. Alternatively, a reflection plate having a substrate separate from the protective glass 13 may be provided in the vicinity of the reflection plate 13.

  The light emitting point is in the bulb 12 made of a glass tube, and an antireflection film 15 is formed on the surface of the glass tube.

  That is, in general, in the light source composed of the parabolic mirror 7 and the bulb 12, the entire area of the opening end of the parabolic mirror 7 is not effective as a light source, and as shown in FIG. The central portion and the peripheral portion, which are the front, are invalid areas where the illumination light reflected by the parabolic mirror 7 does not pass. Therefore, the reflectors 14a and 14b are formed in such invalid areas.

  The reflecting plates 14a and 14b are preferably formed as close to the light emitting point of the light source as possible. This is because, as shown in FIG. 7, when the reflectors 14a and 14b are separated from the light emitting point, the ratio of the luminous flux shielded by the glass tube of the bulb 12 in the recycled light increases. Therefore, as shown in FIG. 8, it is preferable that the reflecting plates 14 a and 14 b be formed on the back surface 13 a of the protective glass 13 to be close to the light emitting point, rather than be formed on the front surface 13 b of the protective glass 13. Further, it can be said that the positions of the reflecting plates 14a and 14b are preferably close to the effective range of the parabolic mirror 7. When the reflectors 14a and 14b are far from the effective range of the parabolic mirror 7, unnecessary primary light (light directly emitted from the light emitting point) cannot be sufficiently shielded, and reflected light to be returned to the light source side is reduced. This is because the ratio of reflection increases.

  Further, the reflection plate 14b around the protective glass 13 may be appropriately inclined with respect to the optical axis as shown in FIG. That is, in this case, the reflecting plate 14b has a conical surface or a shape that is a part of a spherical surface. When the reflecting plate 14 b is not tilted, the light beam reflected by the reflecting plate 14 b reaches a range that greatly spreads in the radial direction on the first fly-eye lens surface 8. By inclining the reflecting plate 14b, the light beam reflected by the reflecting plate 14b can be prevented from spreading on the first fly-eye lens surface 8. The inclination angle of the reflecting plate 14b is determined by the relationship between the focal length of the parabolic mirror 7 and the size of the light emitting point.

[Configuration of light source to improve recycling efficiency (2)]
As shown in FIG. 10, even when the light source is configured using a bulb 12, a spheroidal elliptical mirror 16 instead of the above-described parabolic mirror, and a protective glass 13, the parabolic mirror is used. As in the case of the light source using, the reflectors 14a and 14b are formed in an ineffective area on the protective glass 13 where the primary light is not transmitted. That is, the reflecting plates 14 a and 14 b are formed at the central portion and the peripheral portion of the protective glass 13.

  However, unlike the parabolic mirror, the elliptical mirror 16 is not effective simply by forming the reflection plates 14a and 14b on the protective glass 13. That is, in this light source, since the light emitting point is placed on the first focus of the elliptical mirror 16, the light (primary light) emitted from this light emitting point is on the second focus of the elliptical mirror 16. To form an image. Therefore, in order to make the recycled light effective, it is necessary to image the light beam reflected by the reflecting plate at the second focal point of the elliptical mirror 16. Therefore, condensing lenses 17a and 17b are disposed in the vicinity of the reflecting plates 14a and 14b. These condensing lenses 17a and 17b are circular and annular lenses disposed in the central portion and the peripheral portion of the protective glass 13 corresponding to the reflecting plates 14a and 14b, respectively. It is made to match the focus of. The recycled light that has passed through the second focal point of the elliptical mirror 16 by the condensing lenses 17a and 17b becomes telecentric in the first reflecting element as described above. Accordingly, the recycled light reflected by the first reflecting element returns to the second focal point of the elliptical mirror 16, and thereafter becomes an effective light beam.

[Configuration of light source to improve recycling efficiency (3)]
As shown in FIG. 11, the light source can be configured to include a bulb 12 having a parabolic mirror 7, a quarter-wave plate 18, and a reflective circularly polarizing plate 19. As described above, the phase change in the reflection by the parabolic mirror 7 is not limited to 180 °, and also changes depending on the incident angle and wavelength. Therefore, in this light source, the incident surface of the parabolic mirror 7 is aligned with P-polarized light or S-polarized light by the action of the quarter-wave plate 18 and the reflective circularly polarizing plate 19. As shown in FIG. 12, the quarter-wave plate 18 has a plurality of (even number) regions 18a, 18b, 18c, 18d, 18a ′, 18b in a radial pattern with the central axis of the parabolic mirror 7 as the axis of symmetry. ', 18c', and 18d '. The slow axis of each region is in a direction of 45 ° with respect to a straight line connecting the central portion of each region and the central axis of the parabolic mirror 7, and the center of the parabolic mirror 7. The direction is orthogonal to the slow axis of the region of positional relationship that is symmetric with respect to the axis. An ultraviolet and infrared cut filter (not shown) is formed between the quarter wavelength plate 18 and the protective glass 13 of the bulb 12.

  As the reflective circularly polarizing plate 19, a cholesteric liquid crystal polymer circularly polarizing plate can be used. Further, it is desirable that the quarter wavelength plate 18 functions in a wide wavelength range. An antireflection film is formed at the air interface.

  The light emitted from the bulb 12 is converted into linearly polarized light by passing through the quarter-wave plate 18 and reaches the reflective circularly polarizing plate 19. At this time, the polarization axis of this light is P-polarized light or S-polarized light with respect to the incident surface of the reflective circularly polarizing plate 19. In the reflective circularly polarizing plate 19, polarized light in one direction is reflected to the light source side.

  The light reflected by the reflective circularly polarizing plate 19 passes through the quarter-wave plate 18, is reflected twice by the parabolic mirror 7, and reaches the quarter-wave plate 18 again. At this time, this light is symmetric through the central axis of the parabolic mirror 7 with respect to the region (for example, 18a) of the quarter-wave plate 18 that is transmitted when reflected by the reflective circularly polarizing plate 19. It reaches the area (for example, 18a '). Since this light has already passed through the quarter-wave plate 18 and the reflective circularly polarizing plate 19, it is aligned with P-polarized light or S-polarized light, and no phase difference is generated. Therefore, by passing through the area of the quarter-wave plate 18 in which the slow axis is orthogonal, the circularly polarized light in the direction opposite to the initial incidence on the reflective circularly polarizing plate 19 is obtained. It passes through the mold circular polarizer 19. In this way, polarization conversion is performed in this light source.

  In FIG. 11, the quarter-wave plate 18 and the reflective circularly polarizing plate 19 are configured to be integrated with the protective glass 13 integrated with the parabolic mirror 7. Alternatively, a separate structure may be used.

  However, it is desirable that the quarter-wave plate 18 is disposed at a position as close as possible to the parabolic mirror 7. This is because when the quarter-wave plate 18 is arranged at a position away from the parabolic mirror 7, a light beam having a large tilt angle with respect to the optical axis is reflected twice by the parabolic mirror 7 and is again 1 This is because when the ¼ wavelength plate 18 is reached, there is a greater possibility that the ¼ wavelength plate 18 will not pass through the region of the ¼ wavelength plate 18 that is in a symmetrical relationship.

  Further, as the position of the reflective circularly polarizing plate 19 moves away from the parabolic mirror 7, the possibility that the reflected light from the reflective circularly polarizing plate 19 reaches the reflecting plate 14b at the peripheral portion increases. In this case, this light does not pass through the quarter-wave plate 18 and reaches the reflection plate 14b as circularly polarized light. When this light is reflected by the reflecting plate 14 b, the phase changes by 180 ° to become reverse circularly polarized light, and passes through the reflective circularly polarizing plate 19. In this case, since it is not affected by the reflection by the parabolic mirror 7 or the bulb 12, the efficiency of the illumination light may be improved.

  In addition, the combination of a quarter wavelength plate and a circularly polarizing plate as described above, but also a combination of a half (1/2) wavelength plate and a reflective linear polarizing plate, exhibits the same effect. It is possible to construct a light source.

[Configuration of light source to improve recycling efficiency (4)]
As shown in FIG. 13, the light source may include a bulb 12 having an elliptical mirror 16, a quarter-wave plate 18, a relay lens 20, a field lens 21, and a reflective circularly polarizing plate 19. .

  As shown in FIG. 14, in the case of a light source equipped with a parabolic mirror 7, the light beam deviating from the focal position of the parabolic mirror 7 is reflected by the reflective circularly polarizing plate 19 and enters the bulb 12 again. At this time, there is a possibility that light is shielded by a shield such as an electrode of the bulb 12. Therefore, in the light source provided with the elliptical mirror 16, as shown in FIG. 15, the light emitting point of the bulb 12 is arranged at the first focal position of the elliptical mirror 16 and relayed to the second focal position of the elliptical mirror 16. The lens 20 is disposed, and the reflection type circularly polarizing plate 19 is disposed at a substantially conjugate point with respect to the reflection position of the elliptical mirror 16 and the relay lens 20. The light incident on the reflective circularly polarizing plate 19 is set in a telecentric state by the field lens 21.

  The light beam reflected by the reflective circularly polarizing plate 19 returns to the same position where the primary light is reflected by the elliptical mirror 16. Then, the light beam reflected by the elliptical mirror 16 returns to a position that is symmetrical with the light emitting point with the first focal point of the elliptical mirror 16 as the center. In other words, the ratio of the light beam shielded by the discharge electrode of the bulb 12 is small.

  As in [Light source structure (3)] described above, the quarter-wave plate 18 is radially divided into a plurality of regions having different slow axis orientations as shown in FIG. Thus, it arrange | positions in the vicinity of the protective glass 13. FIG. Even if the quarter-wave plate 18 is disposed between the reflective circularly polarizing plate 19 and the field lens 21, the same effect can be obtained.

  The quarter-wave plate 18 desirably functions in a wide wavelength range. Further, an ultraviolet and infrared cut filter (not shown) is formed between the quarter wavelength plate 18 and the protective glass 13 of the discharge lamp.

  As the reflective circularly polarizing plate 19, a cholesteric liquid crystal polymer circularly polarizing plate can be used. An antireflection film 23 is formed at the air interface.

  The light emitted from the bulb 12 is converted into linearly polarized light by passing through the quarter-wave plate 18 and reaches the reflective circularly polarizing plate 19. At this time, the polarization axis of this light is P-polarized light or S-polarized light with respect to the incident surface of the reflective circularly polarizing plate 19. In the reflective circularly polarizing plate 19, polarized light in one direction is reflected to the light source side.

  The light reflected by the reflective circularly polarizing plate 19 passes through the quarter-wave plate 18, is reflected twice by the elliptical mirror 16, and reaches the quarter-wave plate 18 again. At this time, this light is symmetric through the central axis of the elliptical mirror 16 with respect to the region (for example, 18a) of the quarter-wave plate 18 that is transmitted when reflected by the reflective circularly polarizing plate 19. It reaches an area (for example, 18a ′). Since this light has already passed through the quarter-wave plate 18 and the reflective circularly polarizing plate 19, it is aligned with P-polarized light or S-polarized light, and no phase difference is generated. Therefore, by passing through the area of the quarter-wave plate 18 in which the slow axis is orthogonal, the circularly polarized light in the direction opposite to the initial incidence on the reflective circularly polarizing plate 19 is obtained. It passes through the mold circular polarizer 19. In this way, polarization conversion is performed in this light source.

In addition, the combination of a quarter wavelength plate and a circularly polarizing plate as described above, but also a combination of a half (1/2) wavelength plate and a reflective linear polarizing plate, exhibits the same effect. It is possible to construct a light source.
[Configuration of lighting equipment to improve recycling efficiency (1)]
Moreover, this illuminating device can also be comprised using the rod integrator 26, as shown in FIG. The rod integrator 26 is a prismatic optical element made of a transparent material, and a light beam enters from one end and exits from the other end. This illuminating device includes a light source 27 having an elliptical mirror 16, a rod integrator 26, and a relay condenser optical system disposed between the light source 27 and the rod integrator 26. The relay condenser optical system includes a condenser lens 28 and a relay lens 29. The condenser lens 28 is disposed at the second focal position of the elliptical mirror 16, and the relay lens 29 is disposed at the focal position of the condenser lens 28.

  In the vicinity of one end where the light beam from the light source 27 of the rod integrator 26 is incident, the reflecting plate 14 having an opening is disposed. As shown in FIGS. 17A and 17B, the reflecting plate 14 can be formed, for example, on the end surface of the rod integrator 26 on the light source 27 side.

  The relay lens systems 30 and 20, the field lens 21, and the first reflecting element 6 are disposed on the light beam incident end side of the rod integrator 26.

  When the recycled light reflected by the first reflecting element 6 returns to the light beam incident end of the rod integrator 26, the illuminance is made uniform by the rod integrator 26. Therefore, the recycled light that has returned to the part other than the opening of the reflecting plate 14 is reflected by the reflecting plate 14. The luminous flux reflected by the reflecting plate 14 efficiently illuminates the object to be illuminated in a state of being uniformed by the rod integrator 26 as in the case of the primary light. The recycled light that has passed through the opening returns to the light source 27. By repeating this process, recycling of the illumination light is achieved.

  In addition, as a light source, you may use what has a parabolic mirror.

[Configuration of lighting device to improve recycling efficiency (2)]
In addition, as shown in FIG. 18, this illuminating device can also be configured by shifting the optical axis of a part of the optical system in parallel to the optical axes of other optical systems. In this illuminating device, a condenser lens 10 is further added between the relay lens 20 and the field lens 21 in the illuminating device shown in FIG. 16, and the optical axis of the optical system after the condenser lens 10 is changed from the light source 27. The relay lens 20 is configured to be shifted parallel to the optical axis of the optical system. On the light source side of the condenser lens 10, a reflector 14 c is disposed at a position symmetrical about the optical axis of the optical system after the condenser lens 10 with respect to the optical axis of the optical system up to the relay lens 20. .

  In this front device, the recycled light reflected by the first reflecting element 6 reaches the reflecting plate 14 c, is reflected by the reflecting plate 14 c, passes through the condenser lens 10 and the field lens 21, and again becomes the first reflecting element 6. To reach. Here, the recycled light reflected again by the first reflective element 6 returns to the rod integrator 26. When the recycled light returns to the end of the rod integrator 26 on the light source side, the illuminance is made uniform by the rod integrator 26. Therefore, the recycled light that has returned to the part other than the opening of the reflecting plate 14 is reflected by the reflecting plate 14. The luminous flux reflected by the reflecting plate 14 efficiently illuminates the object to be illuminated in a state of being uniformed by the rod integrator 26 as in the case of the primary light. The recycled light that has passed through the opening returns to the light source 27. By repeating this process, recycling of the illumination light is achieved.

[Configuration of Image Display Device with Polarization Conversion Function (1)]
An image display device using the illumination device according to the present invention can be configured, for example, in FIG. As shown in FIG. 19A, the image display device includes a light source 27 having an elliptical mirror 16, a relay lens 28, a field lens 29, a reflector 14 having an opening, a rod integrator 26, and a condenser lens 30. In addition, a modulation element 31 is added to an illumination device including the relay lens 20, the reflection plate 14c, the condenser lens 10, the field lens 21, and the reflective polarizing plate 6. The optical axis of the optical system after the condenser lens 10 is arranged in parallel with the optical axis of the optical system from the light source 27 to the relay lens 20. In this image display device, the polarization conversion function is achieved by the illumination device 27 and the reflective polarizing plate 6. As in the embodiment described above, a cholesteric liquid crystal polymer circularly polarizing plate is used as the reflective polarizing plate 6.

  Illumination light emitted from the light source 27 passes through the relay lens 28, the field lens 29, the rod integrator 26, the condenser lens 30, the relay lens 20, the condenser lens 10, and the field lens 21, and reaches the reflective polarizing plate 6, as shown in FIG. As shown in (b), one circularly polarized light is transmitted through the reflective polarizing plate 6 and the other circularly polarized light is reflected. The reflected circularly polarized light reaches the reflecting plate 14c, and is reflected by the reflecting plate 14c to become reversely polarized circularly polarized light. This light reaches the reflective polarizing plate 6 again and passes through the reflective polarizing plate 6. The light transmitted through the reflective polarizing plate 6 in this way reaches the modulation element 31 and is subjected to spatial modulation according to the display image by the modulation element 31.

  If linearly polarized light needs to be incident on the modulation element 31, a quarter-wave plate may be disposed between the reflective polarizing plate 6 and the modulation element 31. Furthermore, unnecessary polarized light can be blocked by adding an absorption type polarizing plate.

  Further, as the reflective polarizing plate, a reflective linear polarizing plate may be used. In this case, a quarter wavelength plate is disposed on the reflecting plate 14 or on the light source side of the reflective linearly polarizing plate.

[Configuration of Image Display Device with Polarization Conversion Function (2)]
This image display device has a light source 27 having an elliptical mirror 16, a relay lens 28, a field lens 29, and an opening, as shown in FIG. 20 (a), FIG. 21 (a) and FIG. The reflection plate 14, the rod integrator 26, the condenser lens 30, the relay lens 20, the reflection plate 14 c, the condenser lens 10, and the field lens 21 are provided, and a modulation element 31 is disposed via a polarization beam splitter 32. Also good. The optical axis of the optical system after the condenser lens 10 is shifted in parallel to the optical axis of the optical system from the light source 27 to the relay lens 20. A quarter wavelength plate 34 is disposed between the condenser lens 10 and the reflection plate 14c. In this image display device, the polarization conversion function is achieved by the polarization beam splitter 32.

  That is, as shown in FIG. 20A, the reflection plate 33 is disposed at a position where the field lens 21 has passed through the polarization beam splitter 32, and the modulation element 31 is disposed on the side surface of the polarization beam splitter 32. The reflection plate 33 and the modulation element 31 are arranged such that their optical path lengths from the field lens 21 are equal to each other via a reflection surface in the polarization beam splitter 32.

  In this image display device, the light emitted from the light source 27 reaches the polarization beam splitter 32 through the illumination optical system. As shown in (b) of FIG. 20, this illumination light is reflected by the reflecting surface of the polarizing beam splitter 32 so that the S-polarized light with respect to the reflecting surface of the polarizing beam splitter 32 reaches the modulation element 31. The P-polarized light passes through the reflection surface and reaches the reflection plate 33 and is reflected by the reflection plate 33. The recycled light reflected by the reflecting plate 33 traces the optical path in the reverse direction, is reflected by the reflecting plate 14c through the quarter wavelength plate 34, and is again converted to S-polarized light by passing through the quarter wavelength plate 34. Then, it reaches the polarization beam splitter 32 again. At this time, since the recycled light is S-polarized light with respect to the reflection surface of the polarization beam splitter 32, it is reflected by the reflection surface and illuminates the modulation element 31.

  Note that the direction in which the optical axis of the optical system after the condenser lens 10 is shifted is such that the distance between the field lens 21 and the reflecting surface of the polarizing beam splitter 32 changes due to the movement of the optical axis, as shown in FIG. It is desirable that the direction is not. This is to allow the spread of the incident angle of the light beam corresponding to the movement of the optical axis. In addition, this configuration also has an effect of improving peak luminance described later.

  If the desired extinction ratio cannot be obtained with one beam splitter, a configuration in which a polarizing beam splitter is added as shown in FIGS. 21A and 21B is used. Can do. That is, in this image display device, the reflection plate 33 is disposed at a position that has passed through the two polarization beam splitters 35 and 32 from the field lens 21, and the modulation element 31 is disposed on the side surface of the second polarization beam splitter 32. Deploy. A reflecting plate 37 is disposed on the side surface of the first polarizing beam splitter 35 via an optical path length adjustment block 36. The reflection plate 33, the modulation element 31, and the reflection plate 37 are arranged such that the optical path lengths from the field lens 21 are equal to each other through the reflection surfaces in the polarization beam splitters 35 and 32. The two polarization beam splitters 35 and 32 are in a positional relationship in which the directions of reflected light are orthogonal when the light beam is reflected on the reflection surface.

  In this image display device, similarly to the image display device shown in (a) of FIG. 20, the recycled light can be returned to the modulation element 31, but two polarizing beam splitters are overlapped. A higher extinction ratio can be obtained.

  Further, when three modulation elements corresponding to the three primary colors of R (red), G (green), and B (blue) are used as the modulation elements, as shown in FIG. A reflecting plate 33 is disposed at a position that has passed through the beam splitter 32 and the optical path length adjustment block 36, and modulation elements 31 a, 31 b, 31 c for the respective colors are provided on the side surfaces of the polarizing beam splitter 32 via color separation prisms 37, 38, 39. Place. The reflection plate 33 and the modulation elements 31a, 31b, and 31c pass through the optical path length adjustment block 36 and the color separation prisms 37, 38, and 39 through the reflection surface in the polarization beam splitter 32, and are mutually connected to the field lens 21. The optical path lengths from are set equal.

  In this image display device, the illumination light is separated into three primary colors of R (red), G (green), and B (blue) by the color separation prisms 37, 38, 39, and the modulation elements 31a, 31b, 31c are displayed on the display image. The image is displayed by performing modulation according to each of the R (red), G (green), and B (blue) color components, and the light beams that have passed through the modulation elements 31a, 31b, and 31c are combined again.

  In FIG. 22, since the direction of the optical axis shift of the optical system after the condenser lens 10 is a direction perpendicular to the paper surface, the optical axis shift is not displayed in the figure, but the light source 27 The configuration of the optical system from the field lens 21 to the field lens 21 is the same as that shown in (a) of FIG. 20 and (a) of FIG.

[Configuration of lighting apparatus for improving peak luminance (1)]
Further, as shown in FIG. 23, an image display device using the illumination device according to the present invention includes a light source 27 having an elliptical mirror 16, a relay lens 28, a field lens 29, a reflector 14 having an opening, a rod integrator. 26, condenser lens 30, relay lens 20, reflector 14c, condenser lens 10, field lens 21, reflective polarizing plate 6, transmissive modulation element 31, and reflective polarizing plate 6 serving as an analyzer are sequentially arranged. Can be configured. The optical axis of the optical system after the condenser lens 10 is arranged in parallel with the optical axis of the optical system from the light source 27 to the relay lens 20.

  In this image display device, the polarization conversion function is achieved by the illumination device 27 and the reflective polarizing plate 6. As in the embodiment described above, a cholesteric liquid crystal polymer circularly polarizing plate is used as the reflective polarizing plate 6.

  The illumination light emitted from the light source 27 passes through the relay lens 28, the field lens 29, the rod integrator 26, the condenser lens 30, the relay lens 20, the condenser lens 10, and the field lens 21, and reaches the reflective polarizing plates 6 and 6. In the reflective polarizing plates 6 and 6, one circularly polarized light is transmitted and the other circularly polarized light is reflected. The reflected circularly polarized light reaches the reflecting plate 14c, and is reflected by the reflecting plate 14c to become reversely polarized circularly polarized light. This light reaches the reflective polarizing plate 6 again and passes through the reflective polarizing plate 6. The light transmitted through the reflective polarizing plate 6 in this way reaches the modulation element 31 and is subjected to spatial modulation according to the display image by the modulation element 31.

  In this image display device, in the reflective polarizing plate 6 serving as an analyzer, a cholesteric liquid crystal polymer circular polarizing plate is formed inside the modulation element 31 as shown in FIG. That is, the modulation element 31 has a structure in which the TFT substrate 48, the alignment layer 45, the liquid crystal layer 46, the alignment layer 47, the transparent electrode 44, the reflective polarizing plate 6 and the substrate 41 are sequentially laminated. Antireflection films 15 and 15 are formed on both surfaces. In addition, the reflective polarizing plates 6 and 6 before and after the modulation element 31 have the spiral directions of the reflective polarizing plates reversed from each other.

  In this image display device, the light beam that has not been modulated by the modulation element 31 passes through the modulation element 31 and is reflected by the reflective polarizing plate 6 to reach the rod integrator 26 or the reflection plate 14c. The light beam reflected by the reflecting plate c becomes counter-twisted circularly polarized light, is reflected by the reflective polarizing plate 6, and reaches the rod integrator 26. This light is made uniform by the rod integrator 26, partly reflected by the reflector 14 provided around the opening at the end on the light source 27 side, and the remaining part that has passed through the opening returns to the light source 27. Recycled light is uniformly illuminated by the rod integrator 26 and uniformly illuminates the modulation element 31 in a state of polarization conversion.

  In this image display device, the liquid crystal mode of the modulation element adopts the VA mode, but a quarter wavelength plate is placed between the cholesteric liquid crystal polymer circularly polarizing plate and the liquid crystal layer to convert it into linearly polarized light. Thus, a liquid crystal such as a TN mode using linearly polarized light can be obtained.

Furthermore, as shown in FIG. 24, this image display device can also be configured using three modulation elements 31a, 31b, and 31c. That is, in this image display device, a light source 27 having an elliptical mirror 16, a relay lens 28, a field lens 29, a reflecting plate 14 having an opening, a rod integrator 26, a condenser lens 30, a relay lens 20, a reflecting plate 14c, Condenser lenses 10 are sequentially arranged, and an illumination optical system in which the optical axis of the condenser lens 10 is shifted in parallel to the optical axis of the optical system from the light source 27 to the relay lens 20 is configured, and light emitted from this optical system Is guided to the first spectral reflection mirror 57 through the mirror 56.
In the first spectral reflection mirror 57, for example, R (red) light is transmitted and G (green) light and B (blue) light are reflected. The R (red) light is reflected by the mirror 62, passes through the relay lens 64, passes through the reflective polarizing plate 6, the transmissive modulation element 31 b, and the reflective polarizing plate 6 serving as an analyzer, and reaches the combining prism 66. The G (green) light and B (blue) light reach the second spectral reflection mirror 58, and for example, G (green) light is transmitted and B (blue) light is reflected. The G (green) light passes through the relay lens 60, passes through the reflective polarizing plate 6, the transmissive modulation element 31 a, and the reflective polarizing plate 6 serving as an analyzer, and reaches the combining prism 66. The B (blue) light is reflected by the mirror 63 through the relay lens 61, passes through the relay lens 65, passes through the reflective polarizing plate 6, the transmissive modulation element 31 c, and the reflective polarizing plate 6 serving as an analyzer, The composition prism 66 is reached.

  In the combining prism 66, R (red) light, G (green) light, and B (blue) light are combined and emitted toward a projection lens (not shown). This light is projected onto the screen by the projection lens.

  In each of the above-described embodiments, a liquid crystal modulation element is used as a modulation element, and light modulated by the modulation element is projected onto a screen via a projection lens (not shown). The modulation element is not limited to the liquid crystal modulation element, and other types of modulation elements may be used. In addition, the configuration for improving the recycling efficiency by the structure of the illumination optical system is not limited to the above-described configuration, and any structure that can improve the recycling efficiency by providing a reflection function at the optimum position of the light source may be used.

  As described above, in the present invention, polarization separation / combination can be achieved at low cost by the light source and the illumination device that can efficiently recycle unnecessary light in the projection device. In addition, when using a single-plate modulation element using a color filter, it becomes possible to improve the light utilization efficiency, and even when using a sequential color type single-plate modulation element, the light utilization efficiency can be improved. Is possible. And it becomes possible to improve the light utilization efficiency of a modulation element with a low aperture ratio, and to increase the peak luminance in a dark screen.

It is a block diagram which shows the outline | summary of a structure of the image display apparatus which concerns on this invention. It is a side view which shows the basic optical path in the illuminating device which comprises the said image display apparatus. It is a side view which shows the optical path at the time of tilting the reflective element in the illuminating device which comprises the said image display apparatus. It is a side view which shows the optical path at the time of shifting the one part optical axis of the optical system in the illuminating device which comprises the said image display apparatus. It is a side view which shows the optical path at the time of shifting the one part optical axis of the optical system in the said image display apparatus. It is a longitudinal cross-sectional view which shows the 1st structure of the light source which comprises the said image display apparatus. It is a longitudinal cross-sectional view which shows the 2nd structure of the light source which comprises the said image display apparatus. It is a longitudinal cross-sectional view which shows the 3rd structure of the light source which comprises the said image display apparatus. It is a longitudinal cross-sectional view which shows the 4th structure of the light source which comprises the said image display apparatus. It is a longitudinal cross-sectional view which shows the 5th structure of the light source which comprises the said image display apparatus. It is a longitudinal cross-sectional view which shows the 6th structure of the light source which comprises the said image display apparatus. It is a front view which shows the structure of the quarter wavelength plate in the 6th structure of the said light source. It is a longitudinal cross-sectional view which shows the illuminating device which comprises the said image display apparatus. It is a longitudinal cross-sectional view which shows the state which has produced the problem in the light source which comprises the said image display apparatus. It is a side view which shows the optical path of the illuminating device which comprises the said image display apparatus. It is a longitudinal cross-sectional view which shows the illuminating device which concerns on this invention. It is the perspective view (a) and top view (b) which show the structure of the rod integrator which comprises the illuminating device which concerns on this invention, and a reflecting plate. It is a longitudinal cross-sectional view which shows the other example of the illuminating device which concerns on this invention. It is the longitudinal cross-sectional view (a) and principle figure (b) which show the other example of the illuminating device which concerns on this invention. It is the longitudinal cross-sectional view (a), principle figure (b), and principal part perspective view (c) which show the further another example of the illuminating device which concerns on this invention. It is the longitudinal cross-sectional view (a) and principle figure (b) which show the other example of the illuminating device which concerns on this invention. It is a longitudinal cross-sectional view which shows the image display apparatus using the illuminating device which concerns on this invention. It is a longitudinal cross-sectional view which shows the other example of the image display apparatus using the illuminating device which concerns on this invention. It is a longitudinal cross-sectional view which shows the other example of the image display apparatus using the illuminating device which concerns on this invention. It is a principal part longitudinal cross-sectional view which shows the structure of the modulation element used for the image display apparatus using the illuminating device which concerns on this invention.

Explanation of symbols

1,27 light source, 12 bulb, 3 polarization conversion element, 4 condenser lens group, 5,31 modulation element, 6 reflection element, 7 parabolic mirror, 14 reflector, 16 elliptical mirror, 20 relay lens, 26 rod integrator, 27 Light source, condenser lens

Claims (2)

A light source having a light emitting part and a reflecting mirror having a curved reflecting surface that reflects light emitted from the light emitting part;
An illumination optical system having a rod integrator that uniformizes the light intensity distribution in the light beam emitted from the light source, and a lens system that emits the light beam emitted from the rod integrator as illumination light;
A first reflecting element disposed so as to reflect unnecessary light that is not used as illumination light out of the luminous flux emitted from the illumination optical system, to the light source side;
An opening for transmitting the light beam from the light source is provided, disposed on one end side of the rod integrator where the light beam from the light source is incident, reflected by the first reflecting element, and An illumination device comprising: a second reflecting element that reflects the transmitted unnecessary light and reflects the reflected light toward the lens system via the rod integrator. A condenser lens is disposed between a relay lens and a field lens constituting a lens system for emitting the illumination light of the rod integrator, and the condenser lens is arranged with respect to the optical axis of the optical system from the light source to the rod integrator. A further reflecting element for shifting the optical axis of the subsequent optical system in parallel and reflecting the unnecessary light reflected by the first reflecting element to the first reflecting element side on the light source side of the condenser lens. The illumination device according to claim 1, further comprising:

Images