JP2000347136A - Illuminating optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illuminating optical system where a dark line on a screen is made less noticeable and a polarization/conversion element is easily worked. SOLUTION: As for the row directions of 1st and 2nd lens arrays 3 and 4, all the rows are positioned so as to be different from each other. Besides, in the 1st and 2nd lens arrays 3 and 4, the dark line on the screen generated by the gap of the center axis part of a cross-dichroic prism is eliminated by the arrangement. Besides, the polarization/conversion element 20 is arranged so that the height direction (horizontal direction shown in figure) of each parallel square pole can be parallel to the deviated row directions of the 1st and 2nd lens arrays 3 and 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical system, and more particularly, to an illumination device suitable for use as a light source of video equipment such as a projector.

[0002]

2. Description of the Related Art FIG. 6 is a view for explaining an example of an illumination optical system according to the prior art. FIG. 6A is a structural view of a main part, and FIG. 6B is a perspective view of a cross dichroic prism. . An optical system using a cross dichroic prism is often used for a projection display device using a liquid crystal light valve. The example shown in FIG. 6 is a system example using a cross dichroic prism, and shows a configuration of a liquid crystal light valve three-plate optical system in which light is combined by the cross dichroic prism.

[0003] As shown in FIG.
The light from the light source 51 reflected by 2 enters a first lens array 53 in which a plurality of first lenses 53a are combined. After passing through the first lens 53a, the emitted light flux is divided into a plurality of partial light fluxes, and the light flux converges near the opening of the second lens array 54 paired with the first lens array 53. The second lens 54a forms and illuminates the liquid crystal light valves 57R, 57G, and 57B, which are surfaces to be illuminated, with the aperture shape of the first lens 53a that forms a pair with the second lens 54a. Further, the light transmitted through the second lens array 54 enters the polarization conversion element 70, and the polarization direction of the light is changed.

The blue light and the green light (hereinafter, B light and G light) are reflected by the dichroic mirror 56a, and the red light (hereinafter, R light) is transmitted. The R light is converted into video information by the R signal conversion liquid crystal light valve 57R. The reflected G light and B light are further separated into reflected G light and transmitted B light by a dichroic mirror 56b, and the G light is converted into video information by a G signal conversion liquid crystal light valve 57G. Since the B light has a different optical path length from the R light and the G light, the B light is converted into video information by the B signal conversion liquid crystal light valve 57B via the relay lenses 58a and 58b. The respective video information converted lights are combined by the cross dichroic prism 60 and the projection lens 61
Is projected on the screen 62.

In the cross dichroic prism 60, as shown in FIG. 6B, four right-angle prisms 60a are arranged so that the right-angle ridges 60b of the four right-angle prisms 60a abut each other to form a right-angle ridge 60b. The structure has a structure in which reflective films of respective colors are attached to two surfaces orthogonal to each other. For this reason, the central axis of the cross dichroic prism 60, which is an aggregate of the right-angle ridge lines 60b of each prism 60a, has a gap. For this reason, when light passing through the center of the cross dichroic prism 60 is projected on the screen 62 via the projection lens 61, a dark line due to the gap between the central axis portions is formed on the screen 62.

FIG. 7 is a view for explaining the generation of dark lines on the screen when light passes through the center of the lens array in the example shown in FIG. 6, and FIG. FIG. 7B is a view taken in the direction of arrows BB in FIG.
(C) is a light flux distribution diagram on the second lens array.
FIG. 8 is a diagram for explaining the generation of dark lines on the screen when light passes through the periphery of the lens array in the example shown in FIG. 6, and FIG. 8
(B) is a view on arrow BB in FIG. 8 (A). Note that FIG.
8, the light source 51 and the reflector 52 shown in FIG. 6 are omitted. FIG. 9 is a diagram for explaining dark lines on the screen in the example shown in FIG.

As explained in the example shown in FIG.
After the light incident on the first lens array 53 passes through the first lens 53a, the emitted light beam is divided into a plurality of partial light beams, and a second lens paired with the first lens array 53 is formed. The light beam converges near the opening of the array 54. The second lens 54a causes the aperture shape of the first lens 53a that forms a pair with the second lens 54a to form and illuminate the liquid crystal light valve 57G that is the surface to be illuminated. Thereafter, the light passes through the cross dichroic prism 60 (only the G light is shown in the examples shown in FIGS. 7 and 8), and forms an image on the screen 62 by the projection lens 61. FIG. 7B shows the illuminance distribution on the screen 62 at that time. Also,
At this time, the distribution of the luminous flux on the second lens array 54 is a discrete distribution as shown in FIG. Here, one lens 5 that is a pair of the lens arrays 53 and 54
Let's pay attention to 3a and 54a.

As shown in FIG. 7A, the light transmitted through the lens 54a located substantially at the center of the lens array 54 is transmitted through the panel and then converted into substantially parallel light through the inside of the cross dichroic prism 60. pass. At this time, the transmitted parallel light is blocked by the gap between the central axes of the cross dichroic prism 60, and travels substantially straight as shown by the thick broken line in FIG. As a result, a dark line 64 appears on the screen 62.

As shown in FIG. 8A, the light transmitted through the lenses located around the lens arrays 53 and 54 is
After passing through the panel, the light becomes substantially parallel oblique light and passes through the inside of the cross dichroic prism 60. At this time, as in the example shown in FIG. 7A, the transmitted parallel light is blocked by the gap between the central axes of the cross dichroic prism 60, and travels obliquely as shown by the thick broken line in the figure. Reaches a little higher than the center on the screen 62, and as a result, appears as a dark line 64 on the screen 62. As described above, the position of the dark line 64 generated on the screen 62 changes depending on the position of the lens on the lens arrays 53 and 54. For this reason, as shown in FIG. 9, dark lines similar to the number of lenses in the row direction (vertical direction in the drawing) of the lens arrays 53 and 54 are visible on the screen 62.

FIG. 10 is a view for explaining another example of an illumination optical system according to the prior art. FIG. 10 (A) is a front view of a first lens array, and FIG. 10 (B) is a second lens. FIG. 10C is a front view of the polarization conversion element.
As means for making it difficult to see dark lines on the screen due to the gap between the central axes of the dichroic prism as described above, there is, for example, one disclosed in JP-A-10-325954. In this publication, as shown in FIG. 10, in order to make dark lines on the screen difficult to see, the shape of the second lens array is shifted in the row direction.

In the first lens array 120A, FIG.
As shown in (A), the small lenses are arranged in a matrix with no shift in M rows and N columns (M = 6, N = 4).
On the other hand, in the second lens array 130A, FIG.
As shown in the figure, the upper part 130Au (from the third line from the top) and the lower part 130Ad (from the fourth line to the sixth line) have a predetermined displacement d3A with respect to the center line Ly in the -x direction. And in the + x direction. Accordingly, the relative displacement d2A between the upper part 130Au and the lower part 130Ad is 2 of the displacement d3A with respect to the center line Ly.
Equal to twice.

FIG. 11 is a view for explaining the polarization conversion element shown in FIG. 10. FIG. 11 (A) is a perspective view, and FIG.
(B) is a partial plan view. The polarization conversion element 140A is
As shown in FIG. 10C, the second lens array 13
In order to correspond to the displacement between the upper part 130Au and the lower part 130Ad of 0A, they are displaced in the -x direction and the + x direction with a predetermined displacement d3A with respect to the center line Sy.

The center of each small lens in the polarization conversion element 140A is located at the center of the polarization separation film 14 of the polarization conversion element 140A.
4 so that the center line Sy substantially coincides with the center in the x direction.
Is shifted in the −x direction from the center line Ly by a shift amount d4A substantially equal to half the width Wp in the x direction of the polarization separation film 144 or the reflection film 145 of the polarization conversion element 140A.

As shown in FIG. 11, the polarization conversion element 140 includes a polarization beam splitter array 141 and a selective phase difference plate 142. However, corresponding to the first and second lens arrays 120 and 130 shown in FIG. 10, the polarization conversion elements corresponding to the third row from the top and the fourth to sixth rows correspond to the polarization conversion elements. The polarization conversion elements are arranged so as to be shifted from each other in the −x direction and the + x direction with respect to the center line Sy in the y direction. The displacement of the polarization conversion element will be described later.

The polarizing beam splitter array 141 includes a plurality of columnar translucent plate members 14 each having a parallelogram cross section.
3 has a shape stuck alternately. The polarization separation film 144 and the reflection film 14 are provided at the interface of the translucent plate 143.
5 are alternately formed. The polarization beam splitter array 141 is composed of the polarization separation film 144 and the reflection film 1.
A plurality of sheet glasses on which these films are formed are attached to each other and cut obliquely at a predetermined angle so that 45 are alternately arranged.

First and second lens arrays 120 and 130
11 passes through the polarization conversion element 140 and passes through FIG.
As shown in (B), the polarization separation film 144 separates the light into s-polarized light and p-polarized light. The p-polarized light passes through the polarization separation film 14.
4 as it is. On the other hand, the s-polarized light is reflected by the polarization separation film 144 of the s-polarized light, further reflected by the reflection film 145, and emitted in a state substantially parallel to the p-polarized light transmitted through the polarization separation film 144 as it is. Selection phase difference plate 142
Is λ at the exit surface of the light passing through the polarization separation film 144.
An optical element in which a / 2 retardation layer 146 is formed, and the λ / 2 retardation layer 146 is not formed on the exit surface of the light reflected by the reflection film 145.

Therefore, the p-polarized light transmitted through the polarization splitting film 144 is converted into s-polarized light by the λ / 2 retardation layer 146 and emitted. As a result, most of the light flux having a random polarization direction incident on the polarization conversion element 140 is s.
The light is converted into polarized light and emitted. Of course, the reflection film 145
Phase difference plate 142 only on the exit surface of the light reflected by
By forming the λ / 2 retardation layer 146, the light can be converted into p-polarized light and emitted.

First and second lens arrays 120A and 120A
The small lens of 0A is an eccentric lens in which the optical axis of the lens does not coincide with the center of the lens, as shown in FIGS. 10A and 10B. Indicates the position of the optical axis of each small lens. The position of the optical axis of the small lens 122Aa in the upper part 120Au (from the top to the third row) of the first lens array 120A is shifted by a shift amount d3A in the −x direction with respect to the lens center of the small lens. Upper part 130 of corresponding second lens array 130A
The position of the optical axis of the Au small lens 132Aa is shifted from the lens center of the small lens by a shift amount d3A in the + x direction.

On the other hand, the small lenses 122Ab of the lower part 120Ad (the fourth to sixth rows) of the first lens array 120A
The position of the optical axis is + x with respect to the lens center of the small lens.
The position of the optical axis of the small lens 132Ab of the lower portion 130Ad of the second lens array 130A is shifted by the shift amount d3A in the −x direction with respect to the lens center of the small lens. It is only shifted.

FIG. 12 is a main part configuration diagram for explaining the small lens (eccentric lens) in which the position of the optical axis shown in FIG. 10 is shifted. Small lens 122Aa (132Ab) or 132
Aa (122Ab) is a decentered lens having a structure equivalent to a lens whose optical axis is shifted from the center of the cut lens by cutting the spherical lens at a predetermined position as shown in FIG. It is. Usually, the entire lens array is often integrally molded by molding. Each of the small lenses 122Aa, 122Ab, 132Aa,
The shift amount of the optical axis position of 132Ab with respect to the lens center is equal to the shift amount d3A with respect to the upper and lower center lines Ly in the second lens array 130A.

FIGS. 13A and 13B are main part structural diagrams for explaining the first and second lens arrays 120A and 130A shown in FIG. 10. FIG. 13A shows one of the upper parts, and FIG. Is a view of one of the lower portions viewed from the y direction. As shown in FIG. 13A, the second lens array 130 corresponding to the small lens 122Aa at the top of the first lens array 120A.
The small lens 132Aa of A is such that the lens center 122a (GC) of the small lens 122Aa coincides with the optical axis 132a (OC) of the small lens 132Aa, and the small lens 122A
The optical axis 122a (OC) of Aa and the lens center 132a (GC) of the small lens 132Aa are arranged to coincide.

Similarly, as shown in FIG. 13B, the small lens 122Ab below the first lens array 120A
And the small lens 13 of the second lens array 130A corresponding to
2Ab is the lens center 122b of the small lens 122Ab
(GC) and the optical axis 132b (OC) of the small lens 132Ab
And the optical axis 122 of the small lens 122Ab
b (OC) and lens center 132b of small lens 132Ab
(GC). At this time, the central axis of the partial light beam L1 incident on the small lens 122Aa is aligned with the small lens 1 corresponding to the small lens 122Aa.
The light is polarized so as to pass through the center of 32Aa. When the polarized partial light beam L1 passes through the small lens 132Aa,
The light is polarized so as to be parallel to the traveling direction of the partial light beam when entering the small lens 122Aa.

Therefore, the position of the optical path of the partial light beam L1 is shifted in parallel in the -x direction by the shift amount d3A with respect to the time of incidence on the small lens 122Aa. On the other hand, small lens 1
Similarly, the position of the optical path of the partial light beam L2 incident on 22b is shifted in parallel in the + x direction by a shift amount d3A in the + x direction due to the polarization action of the small lenses 122b and 132b. Accordingly, the position of the optical path of the partial light beam passing through the upper and lower portions of the same row of the first and second lens arrays 120A and 130A is relatively shifted d.
It will be shifted by 2 times 3A.

FIGS. 14 and 15 are main configuration diagrams for explaining the functions of the first and second lens arrays 120A and 130A and the polarization conversion element 140A in the example shown in FIG. FIG. 14 shows the first and second lens arrays 120.
A, the optical path of two partial light beams L32Aa and L32Ab passing through the third row and second column of 130A. The two partial light beams L32Aa and L32Ab have their central axes 3
2Aacl and 32Abcl are incident angles θ32Aa and θ32Ab with respect to the illuminated area 252a at the illuminated area 252.
Each passes through the center of a.

FIG. 15 shows the optical paths of two partial light beams L42Aa and L42Ab passing through the fourth and second columns of the first and second lens arrays 120A and 130A. The two partial light beams L42Aa and L42Ab have their central axes 42Aacl and 42Abcl set to the illuminated area 25.
At the incident angles θ42Aa and θ42Ab with respect to 2a, the light passes through the center of the illuminated area 252a.

Here, the first and second lens arrays 120
A, 130A and the shift amount of the polarization conversion element 140A are as follows: d2A = d1A / 4, d3A = d2A / 2, d4A = d
1A / 4. At this time, dark lines formed by the M partial light beams in the same column direction are the first and second lens arrays 120A, 120A.
It is separated into two parts corresponding to the upper part and the lower part of 30A. Due to this shift, if the incident angles of the partial light beams are different, the positions of the dark lines formed by the respective partial light beams are different as described in the example shown in FIG. Therefore, the dark line formed by each of the M partial light beams divided in the same column direction is not concentrated at one place, and the dark line can be made inconspicuous.

[0027]

However, the above-mentioned prior art has the following problems. (1) When the dark line on the screen, which is generated by the light beam emitted from the pair of lenses of the first and second lens arrays, has very distinct characteristics and is clearly visible on the screen, as described above, 1 / 2,1 small lens
Even if the small lens is shifted with a shift width like / 3, 1/4,
When all the lens arrays were synthesized, the dark lines on the screen could not be made sufficiently inconspicuous.

(2) The polarization conversion element is prepared by laminating a plurality of glass sheets having these films formed thereon such that the polarization separation films and the reflection films are alternately arranged, and cuts obliquely at a predetermined angle. FIGS. 10 and 11
As can be seen from the example shown in FIG.
The structure has no steps in the direction. On the other hand, in the above-described conventional technology, when the lens array is shifted in the row direction (X direction), the polarization conversion element also needs to have a step in the y direction for each area shifted in the row direction. In order to obtain the structure as shown in FIGS. 10 and 11, a polarization conversion element having a basic structure without a step was manufactured, cut at a required dimension in the y direction, and then provided with a required displacement. It is necessary to take a method such as pasting again. For this reason, as the number of regions shifted in the row direction of the lens array is increased, the number of cuts and attachments of the polarization conversion element is increased, and the processing of the polarization conversion element becomes more difficult, leading to an increase in cost. .

The present invention has been made in consideration of the above-described circumstances, and has as its object to provide an illumination optical system that makes dark lines on a screen inconspicuous and allows easy processing of a polarization conversion element. It is a thing.

[0030]

According to a first aspect of the present invention, there is provided a light-emitting source, and a light-collecting means for converting light emitted from the light-emitting source into a light beam directed in a single direction. A first lens array combining a plurality of first lenses having a second lens array paired with the first lens array and combining a plurality of second lenses, the first lens array The lens divides the light beam emitted from the condensing unit into a plurality of partial light beams and converges the light beam near the opening of the second lens that forms a pair with the first lens, and the second lens is In an illumination optical system that forms and illuminates the aperture shape of the first lens that forms a pair with the second lens on the surface to be irradiated, the first and second lens arrays each include the first and second lens arrays. A single-row lens in which the second lens is arranged in a row in the row direction Has a plurality of ray in a direction perpendicular to the row direction, are arranged at positions shifted from each other in relatively the row direction in the row lens array all rows of said plurality of,
The one-row lens array arrangement in the first and second lens arrays is substantially the same.

According to a second aspect of the present invention, in the illumination optical system according to the first aspect, the columnar glass having a parallelogram cross section disposed before or after the second lens array and having a parallelogram cross section is formed. A plurality of polarized light separating films and reflecting films formed on two surfaces parallel to each other are alternately arranged, and each of the columnar glasses passes through the first or second lens. A polarizing beam splitter array for separating the divided partial light beam into two linearly polarized light beams, wherein the polarizing beam splitter array has a column height direction of the columnar glass parallel to a row direction of the first and second lens arrays. It is characterized by being arranged so that

According to a third aspect of the present invention, in the illumination optical system according to the first aspect, at least four types of shift amounts between the respective one-row lens arrays and the adjacent one-row lens arrays are not the same for adjacent shifts. Is characterized by having a shift amount of

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a main part of an illumination optical system according to an embodiment of the present invention. The light of the light source 1 reflected by the reflector 2 enters the first lens array 3 in which a plurality of lenses are combined, and after passing through the lenses, divides the emitted light beam into a plurality of partial light beams.
Second lens array 4 paired with first lens array 3
The light flux is converged in the vicinity of the opening. The second lens 4
“a” causes the aperture shape of the first lens 3a forming a pair with the aperture to form an image on the liquid crystal light valves 7R, 7G, and 7B, which are the surfaces to be irradiated. Further, the light transmitted through the second lens array 4 is incident on the polarization conversion element 20, and the polarization direction of the light is changed.

The blue light and the green light (hereinafter, B light and G light) are reflected by the dichroic mirror 6a, and the red light (hereinafter, referred to as "light").
R light) is transmitted. The R light is converted into video information by the R signal conversion liquid crystal light valve 7R. The reflected G light and B light are further separated by a dichroic mirror 6b into reflected G light and transmitted B light, and the G light is converted into video information by a G signal conversion liquid crystal light valve 7G. B light is R
Since the light and G light have different optical path lengths, the B signal conversion liquid crystal light valve 7B is provided via the relay lenses 8a and 8b.
Is converted into video information. The respective converted video information lights are combined by the cross dichroic prism 10 and projected on the screen 12 by the projection lens 11.

At this time, according to the embodiment shown in FIG. 1, a lamp (light source) 1 and a reflector 2 for reflecting the light are arranged in the y direction as shown in FIG. Has become. This is because it is very difficult to make dark lines on the screen inconspicuous by the cross dichroic prism, and this can only be solved by this method using two lamps 1.

FIG. 2 is a diagram for explaining the positional relationship around the lens array of the embodiment shown in FIG. 1. FIG. 2 (A) is a conventional lens array, and FIG. 2 (B) is a lens according to the present invention. FIG. 2C is a diagram showing a positional relationship among a lens array, a lamp, and a reflector. FIG. 2 (A), FIG. 2 (B)
Is a view of the lens array viewed from the way the light is incident.
As shown in FIG. 2A, the conventional lens array has a shape in which the lenses are aligned, but the lens array according to the present invention, as shown in FIG. The lens arrays arranged in a line are arranged at positions shifted relative to each other in the row direction in all rows. That is, in each row, the lens arrangement is such that no one lens is arranged at the same position. FIG. 2 (C)
FIG. 3 is a diagram showing a positional relationship between a lens array, a lamp, and a reflector, in which two lamps are mounted one above and below the lens array in order to mount two lamps.

FIG. 3 is a view for explaining the shape and positional relationship of the first lens array (A), the second lens array (B) and the polarization conversion element (C) of the embodiment shown in FIG. It is. The first and second lens arrays 3 and 4 have almost the same specifications including the displacement of the lenses in the row direction. Also,
In the row direction of each lens array, the positions of all rows are different from each other, and as described later, this can eliminate dark lines on the screen caused by gaps in the central axis of the cross dichroic prism. it can. Further, the polarization conversion element 20 is arranged such that the height direction (lateral direction in the drawing) of each parallel quadrangular prism and the row direction with a shift of the first and second lens arrays 3 and 4 are parallel to each other. Have been.

In the conventional method, when the lens array is displaced in the row direction, it is necessary to provide a step in the y direction also for the polarization conversion element for each region shifted in the row direction.
In order to manufacture a polarization conversion element having a structure as shown in FIG. 11, first, a plurality of elements having a basic structure without a step are manufactured, cut at a predetermined dimension in the y direction, and a necessary shift is applied. It is necessary to take a method such as pasting again.
For this reason, there is a problem that as the number of regions shifted in the row direction of the lens array increases, the number of cuts and attachments of the polarization conversion element increases, and the processing of the polarization conversion element becomes more difficult.

On the other hand, according to the present invention, the structure as shown in FIG.
There is no need to have steps. In other words, since the step direction of the lens array and the column direction of the polarization conversion element are parallel to each other, the displacement of the lens array is absorbed by the column direction of the polarization conversion element. However, it is possible to cope with a polarization conversion element having no step which is easy to process and manufacture.

FIG. 4 is a diagram for explaining the characteristics of the lamp image of the embodiment shown in FIG. 5A and 5B are diagrams for explaining how dark lines appear on the screen when the shift in the row direction of the lens array of the embodiment shown in FIG. 1 is changed. FIG. FIG. 5 (B) shows how the dark lines appear on the screen for the lenses in each row (the numbers in FIG. 4 (B) indicate the directions in FIG. 4 (B)). (Corresponding to the indicated lens row number), and FIG. 5C is a composite of dark lines on the screen formed by the lenses in each row of the lens array.

The manner in which the lens of the embodiment shown in FIG. 1 is shifted in the row direction will be described. First, consider a system in which two lamps are arranged side by side as shown in FIGS. 1 and 2 (C). In this case, the light transmitted through the first lens array 3 is converged by the first lens 3a in the vicinity of the second lens array 4, and as a result, the image of the lamp 1 is formed in the vicinity of the second lens array 4. Form.

FIG. 4 shows the characteristics of the lamp image. As shown in FIG. 4A, the lamp image formed on each lens 4a of the second lens array 4 has two lamps 1a. 3 and 4 and rows 9 and 10 corresponding to the respective centers of
Is large, and has a size almost close to the lateral width of each lens. On the other hand, in the other rows, the lamp image is small, and is considerably smaller than the width of each lens. Here, when the lamp image of the second lens array 4 is smaller than the lateral width of each lens, and when the lamp image is almost close to the lateral width of each lens, a dark line on the screen generated by the gap between the central axes of the cross dichroic prism. Think level.

When the lamp image of the second lens array 4 is considerably smaller than the lateral width of each lens, the state almost coincides with the state shown in FIG. . In this case, that is, when the light converges extremely at one point, the dark line generated by the gap between the central axes of the cross dichroic prism becomes very strong. This is because, in the case of a lamp image converged at one point, light transmitted through the cross dichroic prism becomes parallel light by the action of the condenser lens 5. In the case of parallel light, as shown in FIG. 7, the dark line generated by the gap between the central axes of the cross dichroic prism thereafter reaches the screen with almost no attenuation. For this reason, the dark line on the screen becomes very strong.

On the other hand, when the lamp image in the second lens array 4 has a size substantially close to the lateral width of each lens,
Contrary to the above, the dark lines on the screen will be very weak. This is because, when the lamp image is large, the light transmitted through the cross dichroic prism is not parallel light but rather diffuse light. In this case, the dark line generated by the gap of the central axis of the cross dichroic prism is overlapped by the light of each angle before reaching the screen due to the diffused light, and the level of the dark line on the screen becomes very small. .

In the case of the embodiment shown in FIG. 4A, if the rows of each lens of the lens array are distinguished depending on whether the above-mentioned dark line becomes stronger or weaker, each lens of the second lens array 4 can be distinguished. Are large in rows 3 and 4 and rows 9 and 10 corresponding to the center of each lamp, and have a size substantially close to the lateral width of each lens. On the other hand, the lamp image is small in the rows other than the above, and is considerably smaller than the lateral width of each lens. For this reason, the dark lines on the screen generated by the light transmitted through the rows 3 and 4 and the rows 9 and 10 of the lens array are weak, and the dark lines on the screen generated by the other lens rows are strong. In FIG. 4B, the rows of lenses where the dark line becomes weaker on the screen are shown by oblique lines.

In FIG. 5, the specification is a specification in which lens displacement is eliminated. On the other hand, as shown in FIG. 4C, assuming that the amount of lens displacement in each row with respect to the first row is Δx, the specifications are as follows. Δ of each lens row at
x is a shift amount obtained by dividing the horizontal width of the lens into 1/4, 1/6, and 1/12. The embodiment shown in FIG.
Specifications and are. In FIG. 5B, the amplitudes of the dark lines in rows 3 and 4 and the rows 9 and 10 where the dark lines become weak are smaller than those when the lenses in the other rows are used. Each of the dark lines is also shifted on the screen by an amount corresponding to the shift amount in the row direction of each row of the lens array. The intervals between the dark lines appearing on the screen in each row are separated by an amount corresponding to the lens width (lens pitch) in the above-mentioned shift amount.

The dark line on the actual screen is shown in FIG.
Will look like the one shown in the above. That is, FIG.
As shown in (C), the condition under which the combined dark line is most difficult to see can be considered as the optimal condition for making the dark line on the screen difficult to see. From this result,
It can be seen that in order for the dark lines on the screen to be most difficult to see, the lenses in each row of the lens array need to be located at different positions in all rows. Further, as can be seen from the embodiment shown in FIG. 5C, it is necessary to arrange the shifting direction and the order such that the combined dark line is the smallest and is less noticeable. In this regard, the specification has been most improved. It has a lens array specification.

[0048]

As is apparent from the above description, according to the present invention, even if the dark line on the screen is quite strong,
By making the amount of displacement in the row direction of each lens array different so that each lens is not located at the same position, the dark line on the screen by the cross dichroic prism is made almost invisible by the arrangement of the lenses. be able to. In the conventional method, a plurality of polarization conversion elements having a basic structure with no steps are prepared, cut at a required dimension in the y direction, and then re-attached with a necessary displacement. It is necessary to use the method described above, and there is a problem that as the number of regions shifted in the row direction of the lens array increases, the number of cuts and attachments of the polarization conversion element increases, and the processing of the polarization conversion element becomes difficult. . On the other hand, according to the present invention, the height direction of each parallel quadrangular prism and the row direction having a shift of the first and second lens arrays are parallel to each other, so that the step direction of the lens array is Since the column direction of the polarization conversion element coincides with the column direction of the polarization conversion element, the displacement of the lens array is absorbed in the column direction of the polarization conversion element, so that the polarization conversion element does not need to have a step. Accordingly, even if the lens array has a large structure with a great deal of misalignment, it can be dealt with with an easy-to-work stepless one.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram for explaining an embodiment of an illumination optical system according to the present invention.

FIG. 2 is a view for explaining a positional relationship around a lens array in the embodiment shown in FIG. 1;

FIG. 3 is a diagram for explaining the shape and positional relationship of a first lens array, a second lens array, and a polarization conversion element of the embodiment shown in FIG. 1;

FIG. 4 is a diagram for explaining characteristics of a lamp image of the embodiment shown in FIG. 1;

FIG. 5 is a diagram for explaining how dark lines appear on a screen when the lens array of the embodiment shown in FIG. 1 is shifted in the row direction.

FIG. 6 is a diagram for explaining an example of an illumination optical system according to the related art.

FIG. 7 is a diagram for explaining generation of dark lines on a screen when light passes through a central portion of a lens array in the example shown in FIG. 6;

FIG. 8 is a diagram for explaining generation of dark lines on a screen when light passes through a peripheral portion of a lens array in the example shown in FIG. 6;

FIG. 9 is a diagram for explaining dark lines on a screen in the example shown in FIG. 6;

FIG. 10 is a diagram for explaining another example of the illumination optical system according to the related art.

11 is a diagram for explaining the polarization conversion device shown in FIG.

12 is a main part configuration diagram for explaining a small lens in which the position of the optical axis shown in FIG. 10 is shifted.

FIG. 13 is a main part configuration diagram for explaining the first and second lens arrays shown in FIG. 10;

FIG. 14 is a main part configuration diagram for explaining functions of first and second lens arrays and a polarization conversion element in the example shown in FIG. 10;

FIG. 15 is a main part configuration diagram for explaining functions of first and second lens arrays and a polarization conversion element in the example shown in FIG. 10;

[Explanation of symbols]

1,51 ... light source, 2,52 ... reflector, 3,53 ... first lens array, 3a, 53a ... first lens, 4,
54: second lens array, 4a, 54a: second lens, 5: condenser lens, 6a, 6b, 56a, 56
b: Dichroic mirror, 7B, 7G, 7R, 57
B, 57G, 57R: liquid crystal light valves, 8a, 8b,
58a, 58b: relay lens, 10, 60: cross dichroic prism, 11, 61: projection lens, 1
2, 62 ... screen, 20, 70 ... polarization conversion element, 6
0a: right angle prism, 60b: right angle ridge line, 64: dark line.

Claims (3)

[Claims] 1. A combination of a light emitting source, light collecting means for converting light emitted from the light emitting source into a light beam directed in a single direction, and a plurality of first lenses having substantially the same aperture shape. A first lens array, and a second lens array in which the first lens array is paired with a plurality of second lenses, wherein the first lens is a light beam emitted from the light collecting means. Is divided into a plurality of partial light beams, and the light beams are converged near the opening of the second lens paired with the first lens, and the second lens forms a pair with the second lens. In the illumination optical system that forms and illuminates the aperture shape of the first lens on the irradiated surface, the first and second lens arrays are arranged such that the first and second lenses are arranged in a line in a row direction. The single-row lens array in a direction perpendicular to the row direction. The plurality of single-row lens arrays are arranged at positions shifted relative to each other in the row direction in all rows, and the single-row lens array arrangement in the first and second lens arrays is substantially the same. An illumination optical system, characterized in that: 2. The illumination optical system according to claim 1, wherein
A polarization separation film and a reflection film, which are arranged before or after the second lens array, and whose cross-sectional shape is a parallelogram, are formed on two parallel surfaces of the parallelogram. A polarizing beam splitter array for separating a plurality of partial luminous fluxes having passed through the first or second lens in each of the columnar glasses into two linearly polarized light beams; An illumination optical system, wherein the polarizing beam splitter array is arranged such that a column height direction of the columnar glass is parallel to a row direction of the first and second lens arrays. 3. The illumination optical system according to claim 1, wherein
An illumination optical system, wherein the amount of shift between each one-line lens array and the adjacent one-line lens array is not the same between adjacent shifts and has at least four types of shift amounts.