Optical element, polarization illumination device, and projector

Abstract

Two polarization conversion element arrays are disclosed. Each polarization conversion element array is composed of a plurality of polarization conversion elements for converting light incident upon the polarization conversion element array to a linearly polarized light beam with a predetermined polarization direction. The plurality of polarization conversion elements are disposed opposite to each other with a predetermined space provided between at about the center of the light-outgoing surface of a lens array in the direction of arrangement. Of the light beams (s-polarized+p-polarized light beams) gathered by the lens array, light beam that is not incident upon the polarization conversion element and passes through the predetermined space is a light beam including a predetermined polarized light beam (s-polarized light beam) that is primarily made to leave the array 320a and an ineffective polarized light beam (p-polarized light beam). Of the light passing through and leaving the space, the required polarized light beam alone can be made to leave as an effective light beam by providing a polarization plate or the like at the light-outgoing side of the space.

Description

(projector) includes the polarization illumination device 50, dichroic mirrors 801 and 804, reflecting mirrors 802, 807, and 809, lenses 806, 808, and 810, three liquid crystal light valves 803, 805, and 811, a cross dichoric prism 813, and a projection lens assembly 814.

The dichroic mirrors 801 and 804 each functions as a color light separating means for separating while light into three color components, red, blue, and green. The three liquid crystal light valves 803, 805, and 811 each functions as a light modulating means for modulating the three color components in order to form an image, in accordance with the image information or signal received. The cross dichroic prism 813 functions as a color light combining means for combining the three color components to form a color image. The projecting lens assembly 814 functions as a projection optical system for projecting the light carrying the combined color image onto a screen 815.

The red component of white light from the polarization illumination device 50 passes through the dichroic mirror 801 reflecting a blue component and a green component, whereas the blue component and the green component are reflected thereto. The red component that has passed there-through is reflected by the reflecting mirror 802 and arrives at the red component liquid crystal light valve 803. On the other hand, of the blue component and the green component reflected by the first dichroic mirror 801, the green component is reflected by the green component reflective dichroic mirror 804 and arrives at the green component liquid crystal light valve 805. The blue component passes through the second dichroic mirror 804.

In the present embodiment, the path of the component is the longest. Thus, for the blue component, following the dichroic mirror 804, a light-guiding means 850 formed by a relay lens unit including the light-incoming lens 806, the intermediate lens 808, and the light-outgoing lens 810 is provided. The blue component, after passing through the green component reflective dichroic mirror 804, passes through the light-incoming lens 806, is reflected by the reflecting mirror 807, and is guided to the intermediate lens 808. Then, after being reflected by the reflecting mirror 809, it is guided to the light-outgoing lens 810 and reaches the blue component liquid crystal light valve 811. The three liquid crystal light valves 803, 805, and 811 correspond to the illumination area 80 of FIG. 1.

In accordance with the image signal (information) provided by an external control circuit (not shown), the three liquid crystal light valves 803, 805, and 811 modulate their corresponding color components to generate color light beams containing image information of the light components. The modulated three color components are incident upon the cross dichroic prism 813. A dielectric multi-layered film reflecting a red component and a dielectric multi-layered film reflecting a blue component are formed into the shape of a cross at the cross dichroic prism 813. These dielectric multi-layered films combine the three color components, forming a light beam representing the color image. The light beam in which the light components have been combined is projected onto the screen 815 by the projecting lens assembly 814 being a projection optical system in order to enlarge the image for display.

The projection display apparatus projection display apparatus uses liquid crystal light valves 803, 805, and 811 serving as light modulating means of the type that modulates a light beam polarized in a particular direction (that is, an s-polarized light beam or a p-polarized light beam). Polarization plates (not shown) are ordinarily affixed onto the light-incoming side and the light-outgoing side of each of the liquid crystal light valves. Therefore, a light beam polarized in a predetermined direction, such as an s-polarized light beam, is modulated and impinges upon the cross dichroic prism 813. Here, of the light beams incident upon the optical element 300, those gathered by the focus lens array 310 and irradiating the polarization separating films 331, as shown in FIG. 10, are all converted into s-polarized light beams and leave the optical element 300. The light beams from the optical element 300 illuminate the liquid crystal light valves 803, 805, and 811 through a light-outgoing side lens 390.

Of the light beams incident upon the optical element 300, those that could not be completely gathered by the focus lens array 310 and irradiate their respective reflecting films 332 are converted into p-polarized light beams, as described in the conventional example, and leave the optical element 300 to illuminate the liquid crystal light valves 803, 805, and 811. As mentioned above, however, polarizing plates are provided at the light-incoming surfaces of the liquid crystal light valves 803, 805, and 811 to block p-polarized light beams, whereby only s-polarized light beams are used. On the other hand, the light beams passing through the space Cp in the optical element of the above-described embodiment of the present invention leave the space Cp and illuminate the liquid crystal light valves 803, 805, and 811, without being converted into a polarized light beam. Since the illuminating light is white light including an s-polarized component usable at the liquid crystal light valves 803, 805, and 811, it is possible to use only the s-polarized component of the light irradiating the liquid crystal light valves 803, 805, and 811. Thus, since the projection display apparatus 800 of FIG. 13 incorporates the polarization illumination device 50 using the optical element 300 of the above-described embodiment of the present invention, it is possible to use the light more efficiently than in the conventional case.

As can be understood from the foregoing description, the optical element of the present embodiment of the present invention can allow light in the projection display apparatus to be used more efficiently than in conventional projection display apparatuses. Therefore, the image projected onto the screen 815 can be made brighter.

While the preferred embodiments of the present invention have been described, it is to be understood that various modifications may be made without departing from the spirit and scope of the appended claims, as follows.

The polarization illumination device of the present invention may be used in apparatuses other than the projection display apparatus of FIG. 13. For example, the polarization beam splitter array in accordance with the present invention may also be applied to a projection display apparatus that does not project a color image, but projects a black-and-white image. In this case, compared to the apparatus of FIG. 13, only one liquid crystal light valve needs to be used, and the color light separating means for separating a light beam into its three color components and a color light combining means for combining the three color components of the light beam are not required. In addition, the present invention can be applied to a projection-type color display apparatus using only one light valve. Further, the present invention can be applied to a projection display apparatus using a reflective light valve or an image display apparatus using the polarization illuminating light of a rear-type display apparatus or the like.

Claims

1. An optical element comprising:

two polarization conversion element arrays for converting polarized light with random polarization directions to one type of polarized light,

wherein each of said two polarization conversion element arrays includes polarization separating surfaces for separating the polarized light with random polarization directions into two types of linearly polarized light and reflecting surfaces for reflecting one of the two types of the linearly polarized light produced by separation by said polarization separating surfaces, said polarization separating surfaces and said reflecting surfaces being alternately arranged between light-transmissive members, and

wherein said two polarization element arrays are separated by a predetermined space with no elements disposed between the two polarization conversion element arrays, said polarization separating surfaces of one of said two polarization conversion element arrays are arranged opposite to said polarization separating surfaces of the other of said two polarization conversion element arrays with respect to the predetermined space.

2. An optical element according to claim 1, further comprising a dummy region including neither said polarization separating surfaces nor said reflecting surfaces, said dummy region being made of a transmissive material and disposed on an end at a predetermined side of each of said two polarization conversion element arrays.

3. An optical element according to claim 1, further comprising a region including neither said polarization separating surfaces nor said reflecting surfaces, said region being made of a transmissive material and disposed on an end opposite to a predetermined space side of each of said two polarization conversion element arrays.

4. An optical element comprising:

a lens array composed of a plurality of lenses disposed in a matrix; and

two polarization conversion element arrays, affixed to one surface of said lens array, the two polarization conversion element arrays converting polarized light with random polarization directions to one type of polarized light,

wherein each of said polarization conversion element arrays include polarization separating surfaces for separating the polarized light with random polarization directions into two types of linearly polarized light and reflecting surfaces for reflecting one of the two types of the linearly polarized light produced by separation by said polarization separating surfaces, said polarization separating surfaces and said reflecting surfaces being alternately arranged between light-transmissive members, and

wherein said two polarization conversion element arrays are separated by a predetermined space with no elements disposed between the two polarization conversion element arrays, said polarization separating surfaces of one of said two polarization conversion element arrays are arranged opposite to said polarization separating surfaces of the other of said two polarization conversion element arrays with respect to the predetermined space.

5. An optical element according to claim 4, further comprising a dummy region including neither said polarization separating surfaces nor said reflecting surfaces, said dummy region being made of a transmissive material and disposed on an end at a predetermined space side of each of said two polarization conversion element arrays.

6. An optical element according to claim 5, wherein a corner at the side of the predetermined space side of said dummy region is removed.

7. An optical element according to claim 4, further comprising a region including neither said polarization separating surfaces nor said reflecting surfaces, said region being made of a transmissive material and disposed on an end opposite to a predetermined space side of each of said two polarization conversion element arrays.

8. An optical element according to claim 4, wherein said polarization separating surfaces and said reflecting surfaces of each of said polarization conversion element arrays are arranged along a direction of arrangement at a pitch that is greater than ½ an arrangement pitch of said lens array disposed along the direction of arrangement of said polarization separating surfaces and said reflecting surfaces.

9. A polarization illumination device comprising:

a light source; and

an optical element for converting light from said light source into one type of polarized light, wherein said optical element includes a lens array composed of a plurality of lenses disposed in a matrix; and

two polarization conversion element arrays, affixed to one surface of said lens array, for converting polarized light with random polarization directions to one type of polarized light,

wherein each of said two polarization conversion element arrays includes polarization separating surfaces for separating the polarized light with random polarization directions into two types of linearly polarized light and reflecting surfaces for reflecting one of the two types of the linearly polarized light produced by separation by said polarization separating surfaces, said polarization separating surfaces and said reflecting surfaces being alternately arranged between light-transmissive members, and

wherein said two polarization conversion element arrays are separated by a predetermined space with no elements disposed between the two polarization conversion element arrays, said polarization separating surfaces of one of said two polarization conversion element arrays are arranged opposite to said polarization separating surfaces of the other of said two polarization conversion element arrays with respect to the predetermined space.

10. A polarization illumination device according to claim 9, further comprising a dummy region including neither said polarization separating surfaces nor said reflecting surfaces, said dummy region being made of a transmissive material and disposed on an end at a predetermined space side of each of said two polarization conversion element arrays.

11. A polarization illumination device according to claim 10, wherein a corner at the predetermined space side of said dummy region is removed.

12. A polarization illumination device according to claim 9, further comprising a region including neither said polarization separating surfaces nor said reflecting surfaces, said region being made of a transmissive material and disposed on an end opposite to a predetermined space side of each of said two polarization conversion element arrays.

13. A polarization illumination device according to claim 9, wherein said polarization separating surfaces are arranged in accordance with a distribution of light leaving said lens array.

14. A polarization illumination device according to claim 9, further comprising a polarization separating surface disposed at a location closest to the predetermined space between said two polarization conversion element arrays, such that a center of said closest polarization separating surface is disposed closer towards the predetermined space than a center of a lens among said plurality of lenses of said lens array which is disposed closest to said closest polarization separating surface.

15. A polarization illumination device according to claim 9, wherein said polarization separating surfaces and said reflecting surfaces of each of said polarization conversion element arrays are arranged along a direction of arrangement at a pitch that is greater than ½ an arrangement pitch of said lens array disposed along the direction of arrangement of said polarization separating surfaces and said reflecting surfaces.

16. A projection display apparatus projector comprising:

a polarization illumination device;

a modulating means for modulating device that modulates light from said polarization illumination device in accordance with a received image signal; and

a projection optical means for projecting lens that projects the light beam modulated by said modulating means device,

wherein said polarization illumination device includes a light source; and an optical element for converting light from said light source incident thereupon to light with a predetermined polarization direction that leaves said optical element, and

wherein said optical element includes a lens array composed of a plurality of lenses disposed in a matrix; and

two polarization conversion element arrays, affixed to one surface of said lens array, for converting polarized light with random polarization directions to one type of polarized light,

wherein each of said two polarization conversion element arrays includes polarization separating surfaces for separating the polarized light with random polarization directions into two types of linearly polarized light and reflecting surfaces for reflecting one of the two types of the linearly polarized light produced by separation by said polarization separating surfaces, said polarization separating surfaces and said reflecting surfaces being alternately arranged between light-transmissive members, and

wherein said two polarization conversion element arrays are separated by a predetermined space with no elements disposed between the two polarization conversion element arrays, said polarization separating surfaces of one of said two polarization conversion element arrays are arranged opposite to said polarization separating surfaces of the other of said two polarization conversion element arrays with respect to the predetermined space.

17. A projection display apparatus projector according to claim 16, further comprising a dummy region including neither said polarization separating surfaces nor said reflecting surfaces, said dummy region being made of a transmissive material and disposed on an end at a predetermined space side of each of said two polarization conversion element arrays.

18. A projection display apparatus projector according to claim 17, wherein a corner at the predetermined space side of said dummy region is removed.

19. A projection display apparatus projector according to claim 16, further comprising a region including neither said polarization separating surfaces nor said reflecting surfaces, said region being made of a transmissive material and disposed on an end opposite to a predetermined space side of each of said two polarization conversion element arrays.

20. A projection display apparatus projector according to claim 16, wherein said polarization separating surfaces are arranged in accordance with a distribution of light leaving said lens array.

21. A projection display apparatus projector according to claim 16, further comprising a polarization separating surface disposed at a location closest to the predetermined space between said two polarization conversion element arrays, such that a center of said closest polarization separating surface is disposed closer towards the predetermined space than a center axis of a lens among said plurality of lenses of said lens array which is disposed closets to said chosen polarization separating surface.

22. A projection display apparatus projector according to claim 16, wherein said polarization separating surfaces and said reflecting surfaces along the light-incoming surface of each of said polarization conversion element arrays are arranged along a direction of arrangement at a pitch that is greater than ½ an arrangement pitch of said lens array disposed along the direction of arrangement of said polarization separating surfaces and said reflecting surfaces.

23. The optical element according to claim 4, wherein each of the polarization separating surfaces being arranged such that a center of each polarization separating surface is disposed closest to a peak of a distribution of light coming out of the lens array.

24. The optical element according to claim 4, further comprising a polarization separating surface disposed at a location closest to the predetermined space between said two polarization conversion element arrays, such that a center of said closest polarization separating surface is disposed closer towards the predetermined space than a center axis of a lens among said plurality of lenses of said lens array which is disposed closest to said closest polarization separating surface.