JP2003240920A - Hybrid integrator, illumination optical system, and projection type picture display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress attenuation of light quantity during the transmission of light through the interior of a hybrid integrator while surely preventing the image of flaws on the light-exiting end of a rod prism or the image of dust from being formed on the element surface of a picture display element by setting the length of a hollow prism to a value which satisfies a specified conditional expression in a hybrid integrator. <P>SOLUTION: Since the length L of the hollow prism 13 is set to satisfy a formula FR×δ≤L≤LW/2 (where, F number at the integrator side of a relay lens 22 is FR; the length of a long side of a rectangular cross section orthogonally intersecting the optical axis of the hollow prism 13 is δ; the overall length of the integrator is LW), a light beam emitted from a defect in the hollow prism 13 forms an image on a point A' on the optical axis even if the defect is found on a point A on the light-exiting end 16 of the rod prism 12. Thus, no image formation state is found on the element surface of the picture display element 23. The length of the hollow prism 13 is set to be shorter than the length of the rod prism 12. Thus, the attenuation of light quantity is suppressed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid integrator, an illumination optical system, and a projection type image display device using the same, which can make the light flux density from a light source uniform in a plane perpendicular to the optical axis. It is about.

[0002]

2. Description of the Related Art Conventionally, in a projection type video projector apparatus or the like, for uniformly illuminating an image display element such as a liquid crystal panel, a luminous flux density equalizing means is provided between the illumination light source and the image display element. Many are configured.

A rod integrator is known as a typical one of the light flux density uniforming means. Known rod integrators are disclosed in, for example, Japanese Unexamined Patent Publication No. 9-33881 and Japanese Unexamined Patent Publication No. 11-326727. These are solid rod-shaped rods made of glass as shown in FIG. 6, for example. It is formed as a prism 100. The rod prism 100 is configured to guide the light beam incident from the light source unit to the light emitting end while totally reflecting the light beam on the inner wall surface a plurality of times. The luminous flux density is made substantially uniform inside. After that, the illumination light whose luminous flux density is made uniform is radiated as backlight light to an image display element such as a liquid crystal panel via a relay lens or the like,
As a result, the light flux carrying the image information is projected onto the screen by the projection lens.

By the way, in such an illumination optical system, the light exit end of the rod prism 100 and the element surface of the image display element are constructed to have an optically conjugate relationship.
The scratches and dust at the light exit end of the rod prism 100 are imaged on the element surface of the image display element. The image of scratches and dust on the light emitting end is superimposed on the image displayed by the image display element, and is projected on the screen at a magnification of about 50 times or more. Since it is difficult to completely remove the scratches and dust on the light exit end of the rod prism 100, it is inevitable that the image quality on the screen is deteriorated when the rod prism 100 is used. There was a problem. If the light emitting end is strictly controlled in the manufacturing process in order to improve this problem to some extent, the manufacturing cost will be increased.

In order to solve such a problem, there is known a hollow prism 105 having an inner surface as a mirror surface as shown in FIG. That is, the hollow prism 105 is formed, for example, by applying a reflection coating on one surface of four rectangular glass plate materials and bonding and assembling in a box-like shape having a rectangular cross section so that the reflection coating surface is the inside. There is.
In the hollow prism 105, the light flux incident from the light source side is reflected a plurality of times by the mirror surface of the inner wall surface of the prism and is guided to the light emission end, and the light emission end has scratches and dust like the rod prism 100 described above. Since there is no end surface that causes the above, no image of scratches or dust is formed on the element surface of the image display element that is in a conjugate relationship with the light emitting end position.

However, such a hollow prism 1
In No. 05, unlike the above-described total reflection on the side surface of the rod prism 100, reflection is caused on the inner wall surface that is made into a mirror surface by the reflection coat, and it is difficult for such a reflection coat on the inner wall surface to make the reflectance 100%. However, when the reflection is repeated a plurality of times on the inner wall surface, the inner reflection loss becomes large, and the light amount of the light reaching the light emission end is significantly reduced. Therefore, the inventor of the present application applied for a patent.
A so-called hybrid type integrator is used in which the rod-shaped rod prism 100 is arranged on the light beam entrance side and the hollow prism 105 is arranged on the light beam exit side as disclosed in the specification of 2001-243198, and both are combined. Is desirable.

[0007]

According to this hybrid type integrator, the rod prism 100 is provided on the element surface of the image display element which has a conjugate positional relationship with the light emitting end.
It is possible to avoid the risk of forming an image of scratches and dust, which has been a problem in the prior art including an integrator that uses only a single lens, and the luminous flux reflection efficiency on the side wall surface is approximately 100%.
Since the rod prism 100 is used, it is possible to suppress the attenuation of the light amount as compared with the conventional technique using only the hollow prism 105.

However, in practice, in order to surely avoid the above-described risk of forming an image of scratches and dust, the light exit end of the rod prism 100 has a conjugate relationship with the element surface of the image display element. It is necessary to be far from the light emitting end of the integrator (hollow prism 105) to the extent that it is largely deviated from, and the total length of the hollow prism 105 is preferably large. On the other hand, in order to reduce the internal reflection loss, it is desirable that the total length of the hollow prism 105 be as small as possible.

The present invention has been made in view of such circumstances, and in a so-called hybrid type integrator in which both a rod prism and a hollow prism are combined, there is a possibility that an image of scratches or dust may be formed on an illuminated object. It is an object of the present invention to provide a hybrid integrator, an illumination optical system, and a projection-type image display device that can surely avoid the internal reflection loss of the hollow prism while avoiding the above.

[0010]

A hybrid integrator according to the present invention receives a light beam from a light source, uniformizes the density of the light beam, and illuminates the light beam with the uniformed density through a relay lens. In the integrator that emits light, a solid rod-shaped first member that is located on the light beam incident side and that guides the light beam from the light source that has entered one end to the other end while totally reflecting it on the side surface, and the light beam emission of this first member A hollow second member that is positioned on the side and guides the light flux from the first member that has entered one end to the other end while being specularly reflected, and emits the light from the other end to the outside. _Let L be the number of F on the integrator side of the relay lens, F _{R be} the length of the long side of the rectangular cross section orthogonal to the optical axis of the second member be δ, and let the total length of the integrator be L _W. To satisfy 1) The one in which the features. _{F R × δ ≦ L ≦ L} W / 2 (1)

Further, the illumination optical system according to the present invention comprises a light source, the hybrid integrator on which the luminous flux emitted from the light source is made incident, and a relay lens arranged at a subsequent stage of the hybrid integrator. It is what

Further, the projection type image display apparatus according to the present invention includes a light source, the hybrid integrator on which the light flux emitted from the light source is incident, a relay lens arranged at a stage subsequent to the hybrid integrator, and the relay. Regarding the lens, an image display element having an element surface disposed in a conjugate positional relationship with the light emitting end of the hybrid integrator, and a projection lens for projecting the light flux, which is optically modulated by the image display element and carries image information, on a screen. It is characterized by having and.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A hybrid integrator, an illumination optical system and a projection type image display device according to embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a projection-type image display device according to an embodiment of the present invention.

This projection type image display device is provided with a light source (not shown) in the left direction of the drawing, and further the condenser lens 2
1, and the hybrid integrator 11 in which the light flux from the light source is condensed at the light incident end 14 by the condenser lens 21. This hybrid integrator 11 is an incident side integrator (rod prism).
Both of 12 and the exit-side integrator (hollow prism) 13 are densely arranged so as to make the luminous flux density uniform in a cross section perpendicular to the optical axis. Further, the hybrid integrator 11, the image display device (the liquid crystal display device,
23), and hybrid integrator 1
The relay lens 22 is provided so that the light emitting end 16 of No. 1 and the element surface of the image display element 23 have an image forming relationship (conjugate relationship) with each other. This imaging relationship is shown by a thick solid line from the light emitting end 16 to the element surface 23 of the image display element in FIG. Further, a projection lens 24 is provided, which magnifies and projects the light flux, which is optically modulated by the image display element 23 and carries image information, on a screen 25. An unillustrated light source, condenser lens 21, hybrid integrator 11, and relay lens 22 constitute an illumination optical system.

FIG. 2 is a schematic perspective view showing the hybrid integrator described above. As described above, the hybrid integrator 11 is configured by combining the solid glass rod prism 12 and the hollow prism 13 having the inner surface with the reflection coating. That is, the rod prism 12 is made of a rod-shaped glass rod having a rectangular cross section, while the hollow prism 13 is a box having a rectangular cross section in which four glass plates each having a reflection coating on one surface are arranged so that the reflection coating surface faces inside. One end of the rod prism 12 is a hollow prism 1.
It is configured to be slightly inserted into the inside of 3.

Incidentally, the rod prism 1 is replaced with the above embodiment.
It is also possible to make the end faces of 2 and the hollow prism 13 in close contact with each other.

In the hybrid integrator 11 thus constructed, as shown in FIG. 3, the light beam output from the light source enters the light incident end 14 of the rod prism 12 arranged on the light source side. Since this light flux enters the light incident end 14 of the rod prism 12 at various angles, the incident angle and the reflection angle on the inner wall surface 15 of the rod prism 12 also vary (however, total reflection occurs at the interface between glass and air). It is assumed that the incident angle occurs, this rod prism 1
The light beam emitted from 2 enters the hollow prism 13 and is reflected by the reflection surface 17 of the inner wall of the hollow prism 13 in the same manner as the reflection on the side surface of the rod prism 12, and is emitted from the light emission end 16 of the hollow prism 13 to the outside. To be done.
Since the hybrid integrator 11 has various reflection modes on the inner wall surface, the light beam is emitted from the light emitting end 16
When the light is emitted from, the light flux density in the cross section perpendicular to the optical axis is made uniform. The hollow prism 1 is shown in FIG.
The shape of the light emitting end 16 of 3 is shown. In addition, δ is the length of the long side of the rectangular end face.

As a result of such a configuration, in the hybrid integrator 11, since the light emitting end 16 is hollow, an image display having a conjugate positional relationship with the light emitting end 16 with respect to the relay lens 22. The image of scratches and dust in the related art may not be formed on the element surface of the element 23. Further, since the length of the rod prism 12 at which the luminous flux reflection efficiency at the side wall surface 12 is approximately 100% occupies a large proportion of the total length of the hybrid integrator 11, the amount of light is greater than that in the conventional technique using only the hollow prism 13. It is possible to suppress the attenuation of.

However, the length of the hollow prism 13 (from the light emitting end of the rod prism 12 to the hollow prism 13)
Distance to the light emission end 16 of the rod prism; the same applies hereinafter) is desirable to be as short as possible, but to the extent that the influence of scratches and dust on the light emission end of the rod prism 12 does not reach the element surface of the image display element 23. Since it is necessary to secure a sufficient length, the length of the hollow prism 13 must be set to an appropriate value that satisfies the above-mentioned two contradictory requirements. Will not be able to get.

Therefore, in this embodiment, the length L of the hollow prism 13 is set so as to satisfy the following conditional expression (1). _{F R × δ ≦ L ≦ L} W / 2 (1) except, F number F _R of the integrator side of the relay lens _22, a rectangular cross-section perpendicular to the optical axis of the hollow prism 13 the length of the long side [delta], the integrator Let L _W be the total length of When the lower limit of this conditional expression (1) is exceeded and L becomes short, defects (scratches and dust) on the light exit end 16 of the rod prism 12 observed on the screen 25 become conspicuous.

When L exceeds the upper limit of the conditional expression (1) and L becomes long, the length of the hollow prism 13 becomes long.
The length exceeds 2 and the effect of suppressing the attenuation of the amount of light is halved, which is not desirable.

That is, according to the hybrid integrator of the embodiment, since the length of the hollow prism 13 is set to a value that satisfies the conditional expression (1), the light exit end 16 of the rod prism 12 is placed. Even if there is a defect (scratch or dust) at the point A, the light ray emitted from this point forms an image at a point A ′ on the optical axis, as is clear from the ray trace shown by the dotted line. After that, the light flux spreads and reaches the element surface of the image display element 23. As shown in the figure, no image is formed on this element surface. That is, the local decrease in illuminance due to a defect or the like existing on the light exit end 16 of the rod prism 12 does not reach the element surface 6 of the image display element 23 and further the screen 25.

In the conditional expression (1), the minimum value is
F_RThe reason for setting δ is as follows. That is, the relay
-The magnification of the lens 22 is β, and the effective diameter of the relay lens 22 is
E, the length of one side of the light emitting end 16 of the hollow prism 13
ε, the effective F number of the relay lens 22 is F_eff, Relay
F number at infinity of lens 22_infAnd when
F _effAnd F_infThe relationship with is expressed by the following equation (2).
Be done.         F_eff= F × (1-β) / E = (1-β) × F_inf(2)

Further, as shown in FIG. 5, the outermost angular ray incident on the relay lens 22 from the point A, the optical axis X, the light exit end of the hollow prism 13 or the two triangles formed by the relay lens 22 are They are similar to each other, and the following expression (3) is obtained. (E / 2) :( 1-β) × f = (ε / 2): L (3)

Therefore, the length L of the hollow prism 13 for forming a flaw or the like at the point A at the light emitting end on the point A'by the relay lens 22 is expressed by the following equation (4). L = ((1-β) × f / E) × ε = F _eff × ε (4) Here, F _eff is replaced with F _R , which is the F number on the integrator side of the relay lens 22, and ε is a hollow prism. Since it is appropriate to set the length δ of the long side of the rectangular cross section orthogonal to the optical axis of 13, the minimum value F _R × δ in the conditional expression (1) described above is obtained.

[0026] In the present embodiment, the length _{L W} of the integrator 50 mm, the length L of the hollow prism 13 is 10 mm, F number of the integrator side of the relay lens 22 _{(F R)} is 1.2, a hollow prism The length δ of the long side of the rectangular cross section orthogonal to the optical axis of 13 is set to 8 mm. According to this, since F _R × δ becomes 9.6 mm, the above conditional expression (1) is satisfied.

In this embodiment, the length of the short side of the rectangular cross section of the hollow prism 13 orthogonal to the optical axis is about 4 m.
It is set to be m, and as is apparent from the aspect ratio, it is configured to correspond to a horizontally wide screen. However, the length of the short side corresponding to the length of the long side can be changed in any way, and the length of the long side and the length of the short side can be made into a square shape. .

Further, the hybrid integrator, the illumination optical system and the projection type image display device according to the present invention can be modified in various modes as compared with those of the above embodiment, for example, the length of the rod prism 12 and the hollow. The length and the like of the prism 13 can be appropriately changed within a range satisfying the conditional expression (1). Further, the illumination optical system equipped with the hybrid integrator can be applied not only to the projection type image display device but also to various devices which require uniform illumination light.

[0029]

As described above, according to the hybrid integrator, the illumination optical system and the projection type image display device of the present invention, the length of the hollow prism is set to a value that satisfies a predetermined conditional expression. . As a result, even if there is a defect (scratch or dust) at the point on the light exit end of the rod prism, it is possible to avoid that the light beam emitted from this point is in a state close to the image formation state on the illuminated body. Therefore, it is possible to reliably prevent the image quality on the illuminated object from being deteriorated.

Further, by making the length of the hollow prism smaller than the length of the rod prism, it is possible to suppress the light quantity attenuation effect.

[Brief description of drawings]

FIG. 1 is a projection-type image display device including a hybrid integrator according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing the hybrid integrator shown in FIG.

FIG. 3 is a schematic diagram showing the operation of the hybrid integrator shown in FIG.

FIG. 4 is a schematic view showing a light emitting end of the hybrid integrator shown in FIG.

5 is a schematic diagram for explaining a conditional expression related to the hybrid integrator shown in FIG.

FIG. 6 is a schematic diagram showing an integrator consisting of only rod prisms.

FIG. 7 is a schematic diagram showing an integrator consisting of only hollow prisms.

[Explanation of symbols]

11 Hybrid integrator 12,100 rod prism 13, 105 Hollow prism 14 Light incident end 15 inner wall surface 16 Light exit end 17 Reflective surface 21 Condenser lens 22 relay lens 23 Image display device 24 Projection lens 25 screen

Claims (3)

[Claims] 1. An integrator which receives a light beam from a light source, makes the density of the light beam uniform, and emits the light beam having the uniformed density to an object to be illuminated through a relay lens. , A solid rod-shaped first member that guides the light beam from the light source that has entered one end to the other end while totally reflecting it on the side surface, and the first member that is positioned on the light beam exit side of the first member and that enters the one end. Guide the light flux from the member to the other end while reflecting it specularly,
A second hollow member to be emitted from the other end to the outside, the length of the second member L, the integrator side of the F number F _R of the relay _lens, rectangle perpendicular to the optical axis of said second member The length of the long side of the cross section is δ, and the total length of the integrator is L
A hybrid integrator that satisfies the following conditional expression (1) when _W is set. _{F R × δ ≦ L ≦ L} W / 2 (1) 2. An illumination comprising a light source, a hybrid integrator according to claim 1, which receives a light beam emitted from the light source, and a relay lens arranged in a subsequent stage of the hybrid integrator. Optical system. 3. A light source, a hybrid integrator according to claim 1, which receives a light beam emitted from the light source, a relay lens arranged in a subsequent stage of the hybrid integrator, and the hybrid integrator for the relay lens. And an image display element having an element surface disposed in a conjugate positional relationship with the light emission end of, and a projection lens for projecting the light beam, which is optically modulated by the image display element and carries image information, on a screen. A projection type image display device.