JP2006106205A - Illumination optical device and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination optical device capable of making a light source image at a part near an illumination optical axis out of light source images formed on a light condensing element very small, and to provide a projector. <P>SOLUTION: In the illumination optical device 2, an optical device 20 is arranged between a 1st lens array 412 and a light source device 411. The optical device 20 is equipped with an optical device main body 21 whose luminous flux emitting side surface is a concave surface 212, and an optical device main body 22 whose luminous flux incident surface is a convex surface 221. The concave surface 212 is curved and recessed from a center point 212A toward an outer circumference edge. The convex surface 221 has shape corresponding to the concave surface 212. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an illumination optical device and a projector.

  Conventionally, for presentations at conferences, academic conferences, exhibitions, etc., an image forming area of a light modulation device (liquid crystal panel) is illuminated by an illumination optical device, and the light beam is light-modulated according to image information with the liquid crystal panel, A projector that enlarges and projects a light-modulated optical image on a screen or the like is known.

The illumination optical device 8 of such a projector has a light source device 411 and a uniform illumination optical system 810 as shown in FIG.
The light source device 411 includes an arc tube (light source lamp) (not shown) as a radiation light source, a reflector 417, and an explosion-proof glass 81, and a light beam emitted from the light source lamp is reflected by the reflector 417 and emitted. is doing.
The uniform illumination optical system 810 has a function of dividing the light beam reflected by the reflector 417 into a plurality of partial light beams and superimposing them on the image forming area of the liquid crystal panel. The uniform illumination optical system 810 includes a first lens array 412 that is a light beam splitting optical element, a second lens array 413 that is a condensing element, a polarization conversion element (not shown), and a condenser lens (not shown). Have.

  More specifically, the light beam from the light source device 411 is divided into a plurality of partial light beams by a first lens array 412 having a plurality of small lenses, and a plurality of small lenses corresponding to the small lenses of the first lens array 412 are further divided. The light is incident on the polarization conversion element through the second lens array 413 having a lens. Then, after the polarization direction of each partial light beam is aligned with S-polarized light or P-polarized light by the polarization conversion element, each light beam with the aligned polarization direction is made incident on the image forming area of each liquid crystal panel via the condenser lens.

  Here, the arc image of the light source lamp of the light source device 411 is not a point light source but has a bright spot formed in the vicinity of the electrode of the light source lamp, and has a finite size T. In addition to this, the light beam reflected by the reflector 417 has a high light beam density in the vicinity of the illumination optical axis S and a low light beam density at the periphery.

For this reason, among the light source images generated on the second lens array 413, the light source images W1 ′ and W2 ′ in the vicinity of the illumination optical axis S are large and are separated from the illumination optical axis S as shown in FIGS. The light source image W3 ′ is smaller (the light source image W1 ′ is not shown in FIG. 7). Therefore, the light source images W1 ′ and W2 ′ in the vicinity of the illumination optical axis S may protrude from the small lenses of the second lens array 413 and reach the adjacent small lenses.
In such a case, the light beam spreads to the outside of the image forming area on the light beam incident side end face of the liquid crystal panel, and there is a problem that the light utilization rate is lowered.

Therefore, as shown in FIGS. 9 and 10, an illumination optical device in which an optical element 90 is inserted between the first lens array 412 and the light source device 411 to prevent a decrease in the light utilization rate in the liquid crystal panel. 9 has been proposed (see, for example, Patent Document 1).
The optical element 90 is composed of a pair of optical element bodies 91 and 92, and an aspheric concave surface 911 is formed on the light beam emission side surface of one optical element body 91 over the entire surface of the light beam emission side surface. A convex surface 921 corresponding to the concave surface 911 is formed on the light incident surface of the other optical element body 92.
The light beam from the light source device 411 is diverged by the aspherical concave surface 911 of one optical element main body 91 and is made parallel by the other optical element main body 92 so that the brightness of the light beam emitted from the optical element 90 is made uniform. ing. Thereby, the size of the optical image formed by the second lens array 413 can be made uniform (see the light source images W1 ″, W2 ″, W3 ″ in FIG. 10).
FIG. 10 is a diagram showing an optical image on the small lens of the second lens array 413.

Japanese Patent Laid-Open No. 11-260144 (9th page, FIGS. 1 and 11)

  However, in such a method, one concave surface 911 is formed on the entire light emission side surface of one optical element body 91, and the light beam from the light source device 411 is diverged by the concave surface 911. The divergence of the light beam passing through the vicinity of the illumination optical axis S (the vicinity of the center point of the concave surface 911) becomes very gradual. Therefore, there is a problem that the optical image in the vicinity of the illumination optical axis S among the light source images on the second lens array 413 cannot be made sufficiently small.

  An object of the present invention is to provide an illumination optical device and a projector that can sufficiently reduce a light source image in the vicinity of an illumination optical axis among light source images formed on a light condensing element.

  An illumination optical device of the present invention is configured by arranging a light source device including a light emitting tube and a reflector that reflects a light beam emitted from the light emitting tube, and a plurality of small lenses in a plane orthogonal to the illumination optical axis, A light beam splitting optical element that splits the light beam emitted from the light source device into a plurality of partial light beams, and a plurality of small lenses corresponding to the plurality of small lenses of the light beam splitting optical element, and is split by the light beam splitting optical element A light condensing element for condensing each of the partial light fluxes, wherein an optical element is disposed on a light beam incident side of the light beam splitting optical element, and the optical element is arranged on the illumination optical axis. A light beam transmitting surface that is a concave surface that is curved and recessed toward the outer peripheral edge with respect to the center point through which the light passes, and another light beam transmitting surface that is located on the light beam exit side of the light beam transmitting surface. The transmission surface depends on the shape of the concave surface A surface, the light beam emitted from the optical device is transmitted through the concave and convex of the optical element, characterized in that it is incident on the beam splitting optical element.

  In the present invention, the light beam emitted from the light source device enters the optical element. This optical element has a light beam transmission surface that is a concave concave surface that is curved toward the outer peripheral edge with respect to the center point through which the illumination optical axis passes. Therefore, the light beam passing near the illumination optical axis is greatly bent and diverged toward the illumination optical axis due to the concave curvature. That is, in the present invention, the light beam transmission surface of the optical element body is curved toward the outer peripheral edge with respect to the center point through which the illumination optical axis passes, and is a concave concave surface, so that the illumination optical axis of the light beam transmission surface passes. The curvature in the vicinity of the center point can be made larger than the curvature in the vicinity of the center point through which the illumination optical axis of the light beam transmission surface of the conventional optical element body passes. Therefore, the light beam passing near the illumination optical axis is greatly bent toward the illumination optical axis side due to the concave curvature and diverges.

In addition, since a shadow is generated by the light emitting device issue tube at and around the center point through which the illumination optical axis of the optical element passes, even if the light beam is greatly bent toward the illumination optical axis side, the light passes through the center point and its surroundings. The density of the luminous flux does not increase.
Then, this light beam is collimated by the curvature of the convex surface which is the other light beam transmitting surface, and enters the optical splitting element.
In this way, the light beam passing through the vicinity of the illumination optical axis of the optical element is largely bent toward the illumination optical axis side by the optical element and is surely diverged, so that it is emitted from the beam splitting optical element and is emitted from the light collecting element. The light source image formed on the nearby small lens is small.
In other words, the optical element has a light beam transmission surface that is a concave surface that is curved and recessed toward the outer peripheral edge with respect to the center point through which the illumination optical axis passes, and a light beam transmission surface that is a convex surface corresponding to the concave surface. Thus, the focal length in the vicinity of the illumination optical axis when the optical element and the beam splitting optical element are combined becomes very short. Therefore, the light source image formed on the small lens in the vicinity of the illumination optical axis of the condensing element becomes small.
Therefore, the light source image can be reliably stored on the small lens of the condensing element. When the light modulation device is installed at the subsequent stage of the illumination optical device, it is possible to prevent a decrease in the utilization factor of the light flux in the light modulation device.

Furthermore, in the present invention, the optical element includes a pair of optical element bodies disposed opposite to each other, and a light beam transmitting surface of one optical element body disposed on the light source device side is the concave surface.
It is preferable that the light beam transmitting surface of the other optical element body is the convex surface corresponding to the shape of the concave surface.
According to the present invention, since the optical element is constituted by a pair of optical element main bodies, the thickness dimension of each optical element main body can be reduced.

In the present invention, the optical element is a single lens, the light beam transmitting surface on the light beam incident side of the optical element is the concave surface, and the light beam transmitting surface on the light beam emitting side is in the shape of the concave surface. It may be the corresponding convex surface.
As in the present invention, the number of members can be reduced by configuring the optical element with a single lens.

  Further, the illumination optical device of the present invention is configured by arranging a light source device including a light emitting tube and a reflector for reflecting a light beam emitted from the light emitting tube, and a plurality of small lenses in a plane orthogonal to the illumination optical axis. A light beam splitting optical element that splits the light beam emitted from the light source device into a plurality of partial light beams, and a plurality of small lenses corresponding to the plurality of small lenses of the light beam splitting optical element. And a condensing element for condensing each partial light beam divided by the above, a diffractive optical element is disposed on a light beam incident side of the light beam splitting optical element, and the diffractive optical element is A lens having the same optical function as a lens having a light beam incident side surface that is a concave surface that is curved and recessed toward the outer peripheral edge with respect to the center point through which the illumination optical axis passes, and a light beam emission side surface that is a convex surface corresponding to the concave surface Be And it features.

The diffractive optical element of the present invention is an optical element composed of a single lens in the illumination optical device described above, which is configured as a diffractive optical element.
Therefore, according to the present invention, an effect similar to that of the illumination optical apparatus having the optical element composed of the single lens described above can be obtained.
Further, the diffractive optical element has an advantage that the thickness dimension is small and an installation space is not required as compared with an optical element constituted by a single lens.
The illumination optical device according to the present invention includes a light source device including a light emitting tube and a reflector that reflects a light beam emitted from the light emitting tube, and a plurality of small lenses arranged in a plane perpendicular to the illumination optical axis. A light beam splitting optical element that splits the light beam emitted from the light source device into a plurality of partial light beams, and a plurality of small lenses corresponding to the plurality of small lenses of the light beam splitting optical element. And a condensing element for condensing each partial light beam divided by the above, a diffractive optical element is disposed on a light beam incident side of the light beam splitting optical element, and the diffractive optical element is A pair of diffractive optical element bodies disposed opposite to each other, and one of the diffractive optical elements disposed on the light source device side is a concave surface that is curved and recessed toward the outer peripheral edge with respect to a center point through which the illumination optical axis passes. The luminous flux transmission side The other diffractive optical element has the same optical function as a lens having a light beam transmission side surface that is a convex surface corresponding to the concave surface. .
The diffractive optical element of the present invention is an optical element constituted by a pair of lenses in the illumination optical device described above, which is configured as a diffractive optical element.
Therefore, according to the present invention, an effect similar to that of the illumination optical apparatus having the optical element composed of the pair of lenses described above can be obtained.
In addition, the diffractive optical element has an advantage that the thickness dimension is smaller than that of an optical element constituted by a lens, and a space for a cooling air passage can be secured.

A projector according to an embodiment of the present invention is a projector that modulates a light beam emitted from a light source device according to image information to form an optical image, and projects an enlarged image. And a projection optical device for enlarging and projecting the formed optical image.
Since the projector according to the present invention includes any one of the illumination optical devices described above, the same effects as any of the illumination optical devices described above can be achieved.
That is, among the light source images on the condensing element, the light source image in the vicinity of the illumination optical axis can be made sufficiently small, and the light utilization rate in the light modulation device can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[1. First embodiment]
[1-1. Overview of optical system]
FIG. 1 is a schematic diagram showing an optical system of the projector 1.
The projector 1 modulates the light beam emitted from the light source device according to image information to form an optical image, and enlarges and projects the formed optical image.
As shown in FIG. 1, the projector 1 includes an illumination optical device 2, a color separation optical system 42, a relay optical system 43, and an optical device 44 in which a light modulation device and a color synthesis optical system are integrated.
The illumination optical device 2 is an optical system for making the luminous flux emitted from the light source uniform in the illumination optical axis orthogonal plane, and includes a light source device 411 and a uniform illumination optical system 410.
The uniform illumination optical system 410 has a function of dividing the light beam reflected by the reflector into a plurality of partial light beams and superimposing them on the image forming area of the liquid crystal panel, and includes the optical element 20 and the first lens array (light beam splitting optical element). 412, a second lens array (light condensing element) 413, a polarization conversion element 414, and a superimposing lens 415.

  The light source device 411 includes a light source lamp (light emitting tube) 416 as a radiation light source and a reflector 417, and the radial light beam emitted from the light source lamp 416 is reflected by the reflector 417 to be a substantially parallel light beam and emitted to the outside. In the present embodiment, a high-pressure mercury lamp is employed as the light source lamp 416, but a metal halide lamp or a halogen lamp may be employed in addition to this. In this embodiment, a parabolic mirror is used as the reflector 417, but a configuration in which a collimating concave lens is arranged on the exit surface of the reflector made of an ellipsoidal mirror can also be used.

The optical element 20 includes a pair of optical element bodies 21 and 22.
The first lens array 412 has a configuration in which small lenses having a substantially rectangular outline when viewed from the illumination optical axis S direction are arranged in a matrix. Each small lens divides the light beam emitted from the light source lamp 416 into partial light beams and emits them in the direction of the illumination optical axis S. The contour shape of each small lens is set so as to be substantially similar to the shape of an image forming area of a liquid crystal panel 441 described later.
The second lens array 413 has substantially the same configuration as the first lens array 412, and includes a configuration in which small lenses are arranged in a matrix. The second lens array 413 has a function of forming an image of each small lens of the first lens array 412 on the liquid crystal panel 441 together with the superimposing lens 415.
The details of the optical element 20 and the relationship between the optical element 20, the first lens array 412, and the second lens array 413 will be described later.

The polarization conversion element 414 converts the light from the second lens array 413 into one type of polarized light, thereby increasing the light utilization rate in the optical device 44.
Specifically, each partial light beam converted into one kind of polarized light by the polarization conversion element 414 is finally substantially superimposed on the liquid crystal panel 441 of the optical device 44 by the superimposing lens 415. In a projector using a liquid crystal panel 441 of a type that modulates polarized light, only one type of polarized light can be used, and therefore approximately half of the light beam from the light source lamp 416 that emits randomly polarized light is not used. For this reason, by using the polarization conversion element 414, all the light beams emitted from the light source lamp 416 are converted into one kind of polarized light, and the light use efficiency in the optical device 44 is enhanced. Note that. Such a polarization conversion element 414 is introduced in, for example, JP-A-8-304739.

The color separation optical system 42 includes two dichroic mirrors 421 and 422 and a reflection mirror 423, and a plurality of partial light beams emitted from the illumination optical device 2 by the dichroic mirrors 421 and 422 are converted into red (R) and green ( G) and blue (B) have a function of separating into three color lights.
The relay optical system 43 includes an incident side lens 431, a relay lens 433, and reflection mirrors 432 and 434, and has a function of guiding red light, which is color light separated by the color separation optical system 42, to the liquid crystal panel 441R. ing.

  At this time, the dichroic mirror 421 of the color separation optical system 42 transmits the red light component and the green light component and reflects the blue light component of the light beam emitted from the illumination optical device 2. The blue light reflected by the dichroic mirror 421 is reflected by the reflection mirror 423, passes through the field lens 418, and reaches the blue liquid crystal panel 441B. The field lens 418 converts each partial light beam emitted from the second lens array 413 into a light beam parallel to the central axis (principal light beam). The same applies to the field lens 418 provided on the light incident side of the other liquid crystal panels 441G and 441R.

Of the red light and green light transmitted through the dichroic mirror 421, the green light is reflected by the dichroic mirror 422, passes through the field lens 418, and reaches the liquid crystal panel 441G for green. On the other hand, the red light passes through the dichroic mirror 422, passes through the relay optical system 43, passes through the field lens 418, and reaches the liquid crystal panel 441R for red light.
The relay optical system 43 is used for red light because the optical path length of the red light is longer than the optical path lengths of the other color lights, thereby preventing a decrease in light use efficiency due to light divergence or the like. Because. That is, this is to transmit the partial light beam incident on the incident side lens 431 to the field lens 418 as it is. The relay optical system 43 is configured to pass red light out of the three color lights, but is not limited thereto, and may be configured to pass blue light, for example.

  The optical device 44 modulates an incident light beam according to image information to form a color image. The optical device 44 includes three incident-side polarizing plates 442 on which the respective color lights separated by the color separation optical system 42 are incident. Liquid crystal panels 441R, 441G, 441B as light modulation devices arranged at the subsequent stage of each incident-side polarizing plate 442, and emission-side polarizing plates 443 disposed at the subsequent stages of the respective liquid crystal panels 441R, 441G, 441B, and color synthesis And a cross dichroic prism 444 as an optical system.

The liquid crystal panels 441R, 441G, and 441B use, for example, polysilicon TFTs as switching elements. Although not shown, a panel body in which liquid crystal is sealed and sealed in a pair of transparent substrates arranged opposite to each other, It is configured to be stored in a holding frame.
In the optical device 44, each color light separated by the color separation optical system 42 is modulated according to image information by the three liquid crystal panels 441R, 441G, 441B, the incident side polarizing plate 442, and the emission side polarizing plate 443. To form an optical image.

The incident side polarizing plate 442 transmits only polarized light in a certain direction out of each color light separated by the color separation optical system 42 and absorbs other light beams. A polarizing film is attached to a substrate such as sapphire glass. It has been done. Further, the polarizing film may be attached to the field lens 418 without using the substrate.
The exit-side polarizing plate 443 is configured in substantially the same manner as the incident-side polarizing plate 442, and transmits only polarized light in a predetermined direction out of the light beams emitted from the liquid crystal panel 441 (441R, 441G, 441B), and transmits the other light beams. Absorb. Further, the polarizing film may be attached to the cross dichroic prism 444 without using the substrate.
The incident side polarizing plate 442 and the exit side polarizing plate 443 are set so that the directions of the polarization axes thereof are orthogonal to each other.

The cross dichroic prism 444 emits from the exit-side polarizing plate 443, and forms a color image by combining optical images modulated for each color light.
The cross dichroic prism 444 is provided with a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light in a substantially X shape along the interface of four right-angle prisms. Three color lights are synthesized by the multilayer film.
The projection lens 445 has a function as a projection optical device that magnifies and projects an optical image formed by the optical device 44, and is configured as a combined lens in which a plurality of lenses are housed in a cylindrical lens barrel. The

[1-2. Configuration of illumination optical device]
The details of the optical element 20 of the illumination optical device 2 and the relationship between the optical element 20, the first lens array 412, and the second lens array 413 will be described with reference to FIGS.
FIG. 2 is a schematic diagram showing the relationship between the optical element 20, the first lens array 412, and the second lens array 413, and FIG. 3 is a diagram showing an optical image on a small lens of the second lens array. is there.
As shown in FIG. 2, the optical element 20 is disposed on the light beam incident side of the first lens array 412, and is disposed between the first lens array 412 and the light source device 411. The optical element 20 has a size that substantially covers the opening of the reflector 417 of the light source device 411.
By disposing such an optical element 20 adjacent to the light source device 411, the explosion-proof glass 81 that is conventionally disposed so as to close the opening of the reflector 417 of the light source device 411 is not required (see FIG. 7).

The optical element 20 includes optical element bodies 21 and 22 that are a pair of lenses.
By configuring the optical element 20 with the optical element bodies 21 and 22 which are two lenses, the thickness dimension of each optical element body 21 and 22 can be reduced.
Of the pair of optical element bodies 21 and 22, the light beam incident side surface (light beam transmission surface) of one optical element body 21 disposed on the light source device 411 side is a flat surface 211. Further, the light emission side surface (light beam transmission surface) of the optical element body 21 is a concave concave surface 212 that is curved from the center point 212A toward the outer peripheral edge with respect to the center point 212A through which the illumination optical axis S passes. Yes.
Therefore, the vicinity of the center point 212A through which the illumination optical axis S on the light beam exit side of the optical element body 21 passes has a shape that protrudes in a substantially conical shape toward the other optical element body 22 side.
Such a cross-sectional shape of the optical element body 21 is such that two concave lenses are arranged adjacent to each other.
The refractive power of the peripheral portion of the concave surface 212 is smaller than the refractive power of the concave surface 212 in the vicinity of the illumination optical axis S. For example, the refracting power of the peripheral portion of the concave surface 212 is approximately zero.

The other optical element body 22 is disposed on the light beam exit side of the one optical element body 21.
The other optical element body 22 has a convex surface 221 whose light beam incident side surface protrudes toward the one optical element body 21. Further, the light emission side (light transmission surface) of the other optical element body 22 is a flat surface 222.
The convex surface 221 has a shape corresponding to the concave surface 212 of the one optical element body 21, and has a shape protruding from the central point 221A toward the outer peripheral edge with the central point 221A through which the illumination optical axis S passes as a reference. It has become. For this reason, the vicinity of the center point 221A through which the illumination optical axis S of the light beam incident side surface (light beam transmission surface) of the optical element body 22 passes is a shape that is recessed in a substantially conical shape on the light beam emission side surface side.
Such a cross-sectional shape of the optical element body 22 is a shape in which two convex lenses are arranged adjacent to each other.

A light beam reflected by the reflector 417 of the light source device 411 enters the optical element 20.
The light beam is bent by a concave surface 212 which is a light beam emission side surface of one optical element body 21 arranged on the light source device 411 side in the optical element 20.
Since the concave surface 212 is curved and recessed from the center point 212A through which the illumination optical axis S passes toward the outer peripheral edge, the light beam passing in the vicinity of the illumination optical axis S is caused by the curvature of the concave surface 212. It bends greatly to the S side and diverges. In other words, in this embodiment, the light flux exit side surface of one optical element body 21 is a concave surface 212 that is curved and recessed from the center point 212A through which the illumination optical axis S passes to the outer peripheral edge. The nearby curvature can be made larger than the curvature in the vicinity of the center point of the light emission side surface of the conventional optical element body 91 (see FIG. 9).

Therefore, the light beam passing through the vicinity of the illumination optical axis S is greatly bent toward the illumination optical axis S due to the curvature of the concave surface 212 and diverges.
In addition, since the shadow by the light source lamp 416 of the light source device 411 is generated at the center point 212A and the periphery thereof (range L in FIG. 2), the center point 212A and the center point 212A and the center point 212A are not affected even if the light beam is greatly bent toward the illumination optical axis S side. The density of the luminous flux in the surrounding area (L range in FIG. 2) does not increase.

The light beam emitted from the concave surface 212 of one optical element body 21 is collimated by the convex surface 221 that is the light beam incident side surface of the other optical element body 22 and is incident on the first lens array 412. In the first lens array 412, the light beam is emitted after being divided into partial light beams. Thereafter, the light beam emitted from the first lens array 412 enters the second lens array 413.
In the present embodiment, the light beam passing through the vicinity of the illumination optical axis S of the optical element 20 is greatly bent toward the illumination optical axis S side and is surely diverged, so that it is emitted from the first lens array 412 and is emitted from the second lens array 413. The light source image formed on the small lens near the illumination optical axis S is small.
In other words, one optical element body 21 of the optical element 20 has a light beam exit side surface that is a concave surface 212 that is curved and recessed from the center point 212A through which the illumination optical axis S passes to the outer peripheral edge, and the other optical element. Since the main body 22 has a light beam incident side surface that is a convex surface 221 corresponding to the concave surface 212, the focal point near the illumination optical axis S when the optical element main bodies 21 and 22 of the optical element 20 and the first lens array 412 are combined. The distance becomes very short. Therefore, the light source image formed on the small lens near the illumination optical axis S of the second lens array 413 is small.
For example, the size of the light source image W1 in FIGS. 2 and 3 is smaller than the size of the light source images W1 ′ and W1 ″ in the illumination optical devices 8 and 9 having the conventional configuration shown in FIGS. It becomes. 2 and FIG. 3 is smaller than the light source images W2 ′ and W2 ″ in the illumination optical devices 8 and 9 having the conventional configurations shown in FIGS.

Thus, since the light source image formed on the small lens in the vicinity of the illumination optical axis S of the second lens array 413 becomes small, the light source image can be reliably placed on the small lens of the second lens array 413. Become. As a result, a decrease in the utilization factor of the light flux in the liquid crystal panel 441 can be prevented.
In particular, since the light source image near the illumination optical axis S has a high contribution to the brightness of the projection image, the projector 1 according to the present embodiment can form a bright projection image.
In addition, the curve (curvature) of the peripheral part of the concave surface 212 of one optical element body 21 of the optical element 20 is almost the same as the curve (curvature) of the peripheral part of the concave surface 911 of the optical element body 91 of the conventional optical element 90. For this reason (see FIG. 9), the size of the light source image on the small lens at the peripheral edge of the second lens array 413 of the present embodiment is the same as the conventional one. For example, the size of the light source image W3 in FIGS. 2 and 3 is substantially the same as the size of the light source image W3 ″ in the illumination optical device 9 having the conventional configuration shown in FIGS.
Further, since the refractive power of the peripheral portion of the concave surface 212 is close to zero, the size of the light source image W3 on the small lens of the peripheral portion of the second lens array 413 of the present embodiment is Is larger than the size of the light source image W3 ′ on the small lens at the peripheral edge of the second lens array 413 in the conventional illumination optical apparatus 8 that does not include (see FIGS. 7 and 8). However, since the contribution of the light source image W3 at the periphery of the second lens array 413 to the brightness of the projected image is low, the light source image W3 may protrude from the small lens at the periphery of the second lens array 413, for example. But it doesn't matter.

[2. Second embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. In the following description, the same parts as those already described are denoted by the same reference numerals and the description thereof is omitted.
In the embodiment, the optical element 20 of the illumination optical apparatus 2 is configured by the optical element bodies 21 and 22 that are two lenses. However, the optical element 50 of the illumination optical apparatus 5 of the present embodiment is It consists of a single lens. The illumination optical device 5 has the same configuration as that of the illumination optical device 2 of the above embodiment in other points.

In the optical element 50, the light incident surface is a concave surface 51 that is curved and recessed from the center point 51A through which the illumination optical axis S passes to the outer peripheral edge. Therefore, the vicinity of the center point 51A through which the illumination optical axis S on the light incident surface of the optical element 50 passes has a shape protruding in a substantially conical shape toward the light source device 411.
The refractive power of the peripheral portion of the concave surface 51 is smaller than the refractive power of the concave surface 51 near the illumination optical axis S. For example, the refractive power of the peripheral edge of the concave surface 51 is close to substantially zero.
On the other hand, the light emission side surface of the optical element 50 is a convex surface 52 corresponding to the concave surface 51. The convex surface 52 has a shape protruding from the center point 52A through which the illumination optical axis S passes so as to curve toward the outer peripheral edge. For this reason, the vicinity of the center point 52A through which the illumination optical axis S on the light beam exit side surface of the optical element 50 passes has a shape recessed in a substantially conical shape on the light beam incident side surface side.

By using such an optical element 50, it is possible to achieve substantially the same effect as in the above embodiment.
That is, since the light incident surface is a concave surface 51 that is curved and recessed from the center point 51A toward the outer peripheral edge, the concave surface 51 is bent greatly toward the illumination optical axis S side to diverge. Then, the light is collimated by the convex surface 52 on the light emission side surface and is incident on the first lens array 412 and the second lens array 413. The light beam passing through the vicinity of the illumination optical axis S of the optical element 50 is largely bent toward the illumination optical axis S side and is surely diverged, so that it is formed on a small lens near the illumination optical axis S of the second lens array 413. The light source image becomes smaller. Therefore, the light source image can be reliably stored on the small lens of the second lens array 413. Accordingly, it is possible to prevent a decrease in the utilization factor of the light flux in the liquid crystal panel 441.
In the present embodiment, since the optical element 50 is constituted by a single element, the number of members can be reduced as compared with the case where the optical element body is constituted by two optical element bodies as in the above-described embodiment. .

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the first embodiment, the optical element 20 includes optical element bodies 21 and 22 that are two lenses. In the second embodiment, the optical element 50 includes a single lens. However, the present invention is not limited to this. For example, as shown in FIG. 5, a single diffractive optical element 60 having the same function as the optical element 50 may be provided.

The illumination optical device 6 shown in FIG. 5 is different from the illumination optical devices 2 and 5 of the above-described embodiments only in that a diffractive optical element 60 is provided instead of the optical elements 20 and 50. It has the same configuration as the illumination optical devices 2 and 5 of each embodiment.
The diffractive optical element 60 has a fine comb-teeth shape on the light incident surface and the light exit surface, and has the same optical function as the optical elements 20 and 50.
Such a diffractive optical element 60 has an advantage that the thickness dimension is smaller than that of the optical element 50 and an installation space is not required. Moreover, there is an advantage that the number of members can be reduced as compared with the optical element 20 configured by two lenses.
In addition, it is good also as what has a diffractive optical element provided with a pair of diffractive optical element main body provided with the same optical function as the optical element 20 comprised from two lenses. The thickness dimension of the individual diffractive optical element bodies constituting such a diffractive optical element can be made smaller than the thickness dimension of the lenses constituting the optical element 20, and the space in the illumination optical device is widened so that the cooling flow path is provided. Cooling efficiency improves because it is easy to secure.

Furthermore, in each said embodiment, although the light source device 411 did not have an explosion-proof glass, it is good not only as this but with an explosion-proof glass. By doing in this way, when the light source lamp 416 of the light source device 411 is ruptured, it is possible to reliably prevent the fragments of the light source lamp 416 from being scattered.
In each of the above embodiments, the projector 1 using three liquid crystal panels is used. However, the present invention is not limited to this, and can be applied to a projector using four or more liquid crystal panels.
Furthermore, in the first embodiment, the vicinity of the center point 212A of the light emission side surface of the optical element body 21 of the optical element 20 has a shape protruding in a substantially conical shape toward the other optical element body 22 side. However, the present invention is not limited to this, and a substantially truncated cone shape (a shape in which the apex portion of the substantially conical shape is cut off to form a flat surface) may be used as in the optical element body 21 ′ of FIG.
Similarly, the shape in the vicinity of the center point 51A of the light incident surface of the optical element 50 of the second embodiment may be substantially frustoconical.
That is, the concave surface of the optical element may not be directly curved from the center point 212A and the center point 51A, and may not be curved in the range L that is a shadow of the light source lamp 416. What is necessary is just to be curved and depressed toward the outer peripheral edge with reference to the center points 212A and 51A.

Further, in the first embodiment, the optical element body 21 of the optical element 20 has the light incident surface on the flat surface 211 and the light emitting surface on the concave surface 212. The light emission side surface may be a flat surface.
Further, in the optical element body 22, the light incident surface is a convex surface 221, and the light emission surface is a flat surface 222. However, the present invention is not limited to this, and the light beam incident surface may be a flat surface and the light emission surface may be a convex surface.
In the embodiment, a transmissive liquid crystal panel having a different light incident surface and light emitting surface is used. However, a reflective liquid crystal panel having the same light incident surface and light emitting surface may be used.
In the embodiment, the liquid crystal panel is used as the light modulation device. However, a light modulation device other than liquid crystal, such as a device using a micromirror, may be used. In this case, polarizing plates on the light beam incident side and the light beam emission side can be omitted.
In the above embodiment, only an example of a front type projector that projects from the direction of observing the screen has been described, but the present invention is also applicable to a rear type projector that projects from the side opposite to the direction of observing the screen. Is possible.

  The illumination optical device of the present invention can be widely used in, for example, other optical devices, optical electronic devices and the like in addition to projector illumination optical devices.

1 is a schematic diagram showing an optical system of a projector according to a first embodiment of the present invention. The schematic diagram which shows the principal part of the illumination optical apparatus of the said projector. The figure which shows the optical image on the small lens of a 2nd lens array. The schematic diagram which shows the principal part of the illumination optical apparatus concerning 2nd embodiment of this invention. The schematic diagram which shows the modification of this invention. The schematic diagram which shows the other modification of this invention. The schematic diagram which shows the principal part of the conventional illumination optical apparatus. The figure which shows the optical image on the small lens of the 2nd lens array of the conventional illumination optical apparatus shown in FIG. The schematic diagram which shows the principal part of the conventional illumination optical apparatus. The figure which shows the optical image on the small lens of the 2nd lens array of the conventional illumination optical apparatus shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Projector, 2 ... Illumination optical apparatus, 5 ... Illumination optical apparatus, 6 ... Illumination optical apparatus, 20 ... Optical element, 50 ... Optical element, 60 ... Diffractive optical element, 21 ... Optical element main body, 22 ... Optical element main body, 51A: Center point, 51 ... Concave surface, 52 ... Convex surface, 52A ... Center point, 212A ... Center point, 212 ... Concave surface, 221A ... Center point, 221 ... Convex surface, 411 ... Light source device, 412 ... First lens array (beam splitting) Optical elements), 413, second lens array (condensing element), 416, light source lamp (light emitting tube), 417, reflector, 441, liquid crystal panel (light modulation device), 441R, liquid crystal panel, 441B, liquid crystal panel, 441G ... Liquid crystal panel, 444 ... Cross dichroic prism (color synthesis optical device), 445 ... Projection lens (projection optical device), S ... Illumination optical axis

Claims (6)

A light source device including a light emitting tube and a reflector that reflects the light beam emitted from the light emitting tube, and a plurality of small lenses arranged in a plane orthogonal to the illumination optical axis, and the light beam emitted from the light source device And a plurality of small lenses corresponding to a plurality of small lenses of the light beam dividing optical element, and condensing each partial light beam divided by the light beam dividing optical element An illumination optical device including a condensing element that performs
An optical element is disposed on a light beam incident side of the light beam splitting optical element, and the optical element has a light beam transmitting surface that is a concave surface curved and recessed toward an outer peripheral edge with respect to a center point through which the illumination optical axis passes. , Other light beam transmission surface located on the light beam emission side than this light beam transmission surface,
The other light flux transmitting surface is a convex surface according to the shape of the concave surface,
The illumination optical device, wherein the light beam emitted from the optical device passes through the concave surface and the convex surface of the optical element and enters the light beam splitting optical element. The illumination optical apparatus according to claim 1,
The optical element includes a pair of optical element bodies disposed opposite to each other, and a light flux transmitting surface of one optical element body disposed on the light source device side is the concave surface.
The illumination optical device according to claim 1, wherein a light beam transmitting surface of the other optical element body is the convex surface corresponding to the shape of the concave surface. The illumination optical apparatus according to claim 1,
The optical element is a single lens,
The illumination optical device according to claim 1, wherein a light beam transmission surface on the light beam incident side of the optical element is the concave surface, and a light beam transmission surface on the light beam emission side is the convex surface corresponding to the shape of the concave surface. A light source device including an arc tube and a reflector that reflects a light beam emitted from the arc tube;
A plurality of small lenses are arranged in a plane orthogonal to the illumination optical axis, and a light beam splitting optical element that splits a light beam emitted from the light source device into a plurality of partial light beams, and a plurality of the light beam splitting optical elements An illumination optical apparatus having a plurality of small lenses corresponding to the small lenses, and a condensing element that condenses each partial light beam divided by the light beam dividing optical element,
A diffractive optical element is disposed on the light beam incident side of the light beam splitting optical element,
The diffractive optical element is the same as a lens having a light beam incident side surface that is a concave surface that is curved and recessed toward the outer periphery with respect to a center point through which the illumination optical axis passes, and a light beam emission side surface that is a convex surface corresponding to the concave surface An illumination optical apparatus having an optical function. A light source device including an arc tube and a reflector that reflects a light beam emitted from the arc tube;
A plurality of small lenses are arranged in a plane orthogonal to the illumination optical axis, and a light beam splitting optical element that splits a light beam emitted from the light source device into a plurality of partial light beams, and a plurality of the light beam splitting optical elements An illumination optical apparatus having a plurality of small lenses corresponding to the small lenses, and a condensing element that condenses each partial light beam divided by the light beam dividing optical element,
A diffractive optical element is disposed on the light beam incident side of the light beam splitting optical element,
The diffractive optical element includes a pair of diffractive optical element bodies disposed opposite to each other,
One diffractive optical element arranged on the light source device side has the same optical function as a lens having a light beam transmission side surface that is a concave surface that is curved and recessed toward the outer peripheral edge with respect to the center point through which the illumination optical axis passes. Is,
2. The illumination optical apparatus according to claim 1, wherein the other diffractive optical element has the same optical function as a lens having a light beam transmission side surface that is a convex surface corresponding to the concave surface. A projector that modulates a light beam emitted from a light source device according to image information to form an optical image, and projects an enlarged image,
An illumination optical device according to any one of claims 1 to 5,
A light modulation device that modulates a light beam emitted from the illumination optical device according to image information to form an optical image;
A projector comprising: a projection optical device that magnifies and projects a formed optical image.

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