JP2000121996A - Image projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image projector having a projection optical system which achieves good image forming performance with a smaller number of lens elements. SOLUTION: This image projector has a color synthesizing mirror 21 for synthesizing respective pieces of image information of display panels 12 and 14 within the projection optical system consisting of a first group 26 and a second group 27 and 28 as well as third groups 29 and 30 and is provided with condenser lenses 18 and 20 respectively between the display panels 12 and 14 and the projection optical system. The image projector is constituted to satisfy the conditions 0.5<θ<5, 3<θ'/13, where θ is the angle formed by the projection main ray of the maximum angle of view emitted from the image display element of a reflection type and an axial main ray and θ' is the angle formed by the projection main ray of the maximum angle of view emitted from the condenser lenses and the axial projection main ray.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image projection device such as a projector, and more particularly, to an image projection device using a reflection type image display device.

[0002]

2. Description of the Related Art Conventionally, in a projector,
Many systems using a reflective image display device, such as a reflective liquid crystal system and a DMD system, have been adopted.

For example, as described in JP-A-3-249639, light emitted from a light source is made incident on a polarizing beam splitter, reflected by the polarizing beam splitter, and made incident on a cross dichroic prism to produce each color. After being separated, modulated by each display panel and reflected, the light passes through a cross dichroic prism and a polarizing beam splitter again, and is incident on a projection optical system. This is an example where the liquid crystal display element as a display panel is of a reflective type.

Further, as disclosed in Japanese Patent Application Laid-Open No. 10-133101, an illumination method for illuminating a liquid crystal display element substantially in parallel is disclosed.

[0005]

However, in the configuration described in Japanese Patent Application Laid-Open No. Hei 3-249639, the projection optical system is telecentric,
Since many lenses are required to obtain good optical performance, the cost is high.

In the configuration described in Japanese Patent Application Laid-Open No. Hei 10-133101, when an attempt is made to illuminate the liquid crystal display element substantially in parallel, the image of the pupil of the projection optical system is changed. And the diameter is almost equal to the diameter of the pupil, so even if you try to arrange a lens array to illuminate the position of the image of the pupil uniformly, the diameter is too small. It will be difficult. Also, from the aperture of the projection optical system to the liquid crystal display element side,
Since it has only a condenser lens, it becomes an asymmetric optical system, and it becomes difficult to correct distortion and the like.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an image projection apparatus having a projection optical system that achieves good imaging performance with a small number of lenses.

[0008]

In order to achieve the above object, the present invention provides a reflection type image display device and a projection optical system for projecting image information of the image display device. A condenser lens is provided between the element and the projection optical system. The projection optical system includes a front group, a stop, and a rear group in order from the object side, and satisfies the following conditional expression. 0.5 <θ <53 3 <θ ′ <13, where θ is the angle formed between the projected principal ray of the maximum angle of view and the axial projected principal ray emitted from the reflective image display element θ ′: emitted from the condenser lens The angle between the projected principal ray at the maximum angle of view and the projected principal ray on the axis.

In addition, the apparatus has at least two reflective image display elements and a projection optical system for projecting image information of the image display elements, and a condenser lens is provided between the image display element and the projection optical system. And an image information synthesizing means for synthesizing the image information of the image display element is provided inside the projection optical system, so that the following conditional expression is satisfied. 0.5 <θ <53 3 <θ ′ <13, where θ is the angle formed by the projected principal ray of the maximum angle of view and the axial projected principal ray emitted from the reflective image display element θ ′: Emitted from the condenser lens The angle between the projected principal ray at the maximum angle of view and the projected principal ray on the axis.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. An image projection device according to an embodiment of the present invention uses a reflection-type liquid crystal display element as a display panel and has a so-called two-story structure.
A projection optical system is arranged on the floor, and an illumination optical system is arranged on the second floor.
Then, light from the illumination optical system is turned back by a mirror above the display panel, and guided to the projection optical system.

FIG. 1 is a cross-sectional view in the XZ plane schematically showing the configuration of the illumination optical system of the present embodiment. A direction perpendicular to the plane of the drawing and on the near side is defined as a Y-axis direction. In the figure, 1 is a light source, 2 is disposed so as to surround the light source 1,
A reflector 3 for reflecting light from the light source 1 is disposed above the light source 1, and a flat UVIR cut filter for blocking ultraviolet and infrared rays out of the light from the light source 1, and a reference numeral 4 is further disposed thereabove. A plate-like first lens array 5 on which a large number of small lenses are arranged on the surface, and a triangular polarization separation block 6 for converting light from the light source 1 into specific polarized light, Is located to the right of it,
This is a plate-shaped second lens array in which many small lenses are arranged on the surface.

Further, on the right side, color separation mirrors 7 and 8 for separating light from the light source 1 into respective color components are sequentially arranged. Further, mirrors 9, 10, and 11 are arranged on the separated optical paths, respectively, and function to guide the respective color components to the display panels 12, 13, and 14, respectively. Details will be described later.

The reflector 2 has a spheroidal reflecting surface, and the light source 1 is arranged at the first focal point of the spheroidal surface. In this case, light emitted from the light source 1 and reflected by the reflector 2 forms an image at a second focus (not shown) without aberration. By doing so, even when the opening of the light source 1 is larger than the opening of the second lens array as in the present embodiment, light does not leak due to the light condensing action. In addition, since the light that has exited the reflector 2 is converged by this light-condensing action, the optical element farther from the light source 1 can be made smaller.
Material costs can be reduced and costs can be reduced.

The first lens array 4 is formed by arranging square lenses similar in shape to the display panel in an array. The first lens array 4 has a function of dividing the light from the light source 1 into a plurality of surface light sources and superimposing the light later to reduce unevenness in illumination on the display panel. Further, the focal length of the first lens array 4 is set such that the light emitted from the reflector 2 is imaged by the second lens array 6.

As shown in FIG. 1, the polarization separation block 5 has a polarization separation mirror surface 5a and a mirror surface 5b, and these two surfaces are arranged at a predetermined interval. Here, when light in a non-polarized state enters the polarization separation block 5, first, only S-polarized light is reflected by the polarization separation mirror surface 5a, and P-polarized light is transmitted. The transmitted P-polarized light is reflected by the mirror surface 5b, passes through the polarization splitting mirror surface 5a again, and exits. Therefore, the unpolarized light that has entered the polarization separation block 5 is emitted in a state where the S-polarized light and the P-polarized light are displaced. Therefore, the light source image formed by the first lens array 4 is formed at different positions between the S-polarized light and the P-polarized light.

A P-polarized image and an S-polarized image are formed on the second lens array 6 arranged at a position where the light emitted from the first lens array 4 forms an image. An array of lenses
Since the number of lenses corresponding to each image is required, the number of lenses of the second lens array 6 is twice the number of lenses of the first lens array 4. The focal length and the inclination of the second lens array 6 are set such that the light source images divided by the first lens array 4 are superimposed on the display panel.

The display panel and the projection optical system are arranged such that the position of the second lens array 4 is in a first-order conjugate positional relationship with the stop of the projection optical system described later. By doing so, the light from the light source 1 can be illuminated on the display panel without waste. In addition, an optical system such as a relay lens for illumination is not required, and the illumination optical system can be configured with a small number of parts, which is advantageous in cost.

In FIG. 1, illumination light in which the direct light from the light source 1 and the reflected light from the reflector 2 are mixed is a UVI light.
The light passes through the R-cut filter 3 and becomes almost only visible light, then passes through the first lens array 4 and further enters the polarization separation block 5. Here, the S-polarized light component of the incident light is reflected by the polarization splitting mirror surface 5a, and the P-polarized light component is reflected by the mirror surface 5b and exits to the second lens array 6. Since the positions where the S-polarized light beam and the P-polarized light beam form an image on the second lens array 6 are different, only the P-polarized light is converted into S-polarized light by a half-wave plate (not shown), so that all of the light is converted into S-polarized light.

The light transmitted through the second lens array 6 is incident on the color separation mirror 7 as a light beam of only S-polarized light, where only the blue light beam B is reflected, and the other light is transmitted. The light transmitted through the color separation mirror 7 subsequently enters the color separation mirror 8, where only the red light flux R is reflected, and the remaining green light flux G is transmitted. The separated blue, red, and green luminous fluxes B, R, and G enter the mirrors 11, 10, and 9, respectively. The reason why the order of the colors to be separated is as described above will be described later.

FIG. 2 is a side view of the vicinity of a mirror that folds the separated light beams. As shown in the figure, the separated light beams G, R, and B are reflected by mirrors 9, 10, and 11, respectively, are turned back, and further enter polarization beam splitters 15, 16, and 17, respectively. At this point, since each light beam is aligned to the S-polarized light as described above, it is reflected without waste when entering the polarization beam splitter. The light beams G, R, and B reflected by the polarization beam splitters 15, 16, and 17 respectively pass through the condenser lenses 18, 19, and 20 and reach the display panels 12, 13, and 14, respectively. With the above configuration, light from the illumination optical system on the second floor is guided to the projection optical system on the first floor.

Each condenser lens 18, 19, 20
Has set its focal length such that all positions on the surface of the display panels 12, 13, and 14 are almost vertically illuminated by light from the illumination optical system. However, if the illumination is made to be completely vertical, the first conjugate image of the aperture of the projection optical system, which will be described later, will be too close to the display panel, and the size of the image will be small. It is not preferable because it becomes difficult to perform the operation, and the second lens array 6 becomes too small. Therefore,
Each condenser lens sets the focal length so that the first conjugate image is sufficiently separated from each display panel and the size of the image is sufficiently large. In addition, each display panel
This is a reflection type liquid crystal display element, where light modulated for each pixel is emitted from the surface.

FIG. 3 is a cross-sectional view in the XZ plane schematically showing the configuration of the projection optical system of the present embodiment. A direction perpendicular to the plane of the drawing and on the near side is defined as a Y-axis direction. In the figure, 12 to 14 are the display panels, 15 to 17 are the polarizing beam splitters, and 18 to 20 are the condenser lenses. Reference numeral 21 denotes a color combining mirror for combining the modulated light beams G and R from the display panels 12 and 13, and reference numeral 22 denotes a light beam obtained by combining the modulated light beam B and the light beams G and R from the display panel 14. And a color combining mirror that combines Reference numeral 23 denotes a dummy glass made of flat glass for making the optical path of the light flux B optically the same as the optical paths of the light fluxes G and R.

On the left side of the figure, a projection screen (not shown) is provided. The projection optical system according to the present embodiment, when viewed from the projection screen, includes a first negative group 26 and a second positive group 26.
Groups 27 and 28, apertures 24 and 25, positive third groups 29,
It consists of 30 lens groups. In addition, between the first negative group 26 and the second positive groups 27 and 28, the color synthesizing mirror 22 that is rotated around the Y axis and tilted is disposed. On the lens back of the third group 29, the color combining mirror 21 rotated around the Y axis and tilted, and the polarization beam splitters 15 and 16 rotated around the X axis and Z axis, respectively, are tilted. It is arranged. Further, the lens back of the third group 30 is provided with the dummy glass 23 rotated around the Y axis and tilted, and the polarization beam splitter 17 rotated around the Z axis and tilted.

In the figure, as described above, each of the light beams G, R, and S incident on each of the display panels 12, 13, and 14 as S-polarized light.
B is selectively modulated into P-polarized light for each pixel, and after being transmitted again through condenser lenses 18, 19 and 20, respectively,
The light again enters the polarizing beam splitters 15, 16, and 17, respectively. Here, only the P-polarized light beam is transmitted. Further, the light fluxes G and R transmitted through the polarization beam splitters 15 and 16 enter the color combining mirror 21, where they are combined and enter the third group 29 of the projection optical system. On the other hand, the light beam B transmitted through the polarizing beam splitter 17 is incident on the dummy glass 23, is synthesized there, and is incident on the third group 30 of the projection optical system.

Thereafter, the light flux and the light flux B obtained by combining the light fluxes G and R pass through the third groups 29 and 30, respectively, and further pass through the apertures 24 and 25 and the second groups 27 and 28, respectively. The light enters the color synthesizing mirror 22 in the projection optical system, where the light fluxes G, R, and B are combined into a combined light flux, transmitted through the first group 26, and projected onto a projection screen (not shown). The projection screen is arranged at a position where the image on each of the display panels is enlarged and formed.

In the projection optical system according to the present embodiment, the lens group is provided before and after the stop, so that distortion and the like are favorably corrected. On the other hand, if there is no lens group behind the stop, for example, the configuration of the lens becomes extremely asymmetric, and it becomes difficult to correct distortion, curvature of field, and the like. Furthermore, since the projection optical system of the present embodiment has a retrofocus type configuration, it is possible to maintain a sufficient lens back while maintaining a relatively large angle of view, and to maintain good optical performance. it can.

By the way, as described above, when the light flux emitted from each display panel passes through each condenser lens, it is desirable to satisfy the following conditional expressions. 0.5 <θ <5 (1) 3 <θ ′ <13 (2) where θ: the angle formed between the projected principal ray of the maximum angle of view and the axial projected principal ray emitted from the reflective display element θ ′: This is the angle between the projected chief ray of the maximum angle of view and the projected chief ray on the axis emitted from the condenser lens.

FIG. 6 is a diagram schematically showing an optical path near the reflective display element and the condenser lens.
FIG. 3B shows the case where the reflective display element is illuminated telecentrically, and FIG. 3B shows the case where the reflective display element is illuminated non-telecentrically. The display panel 12 of the present embodiment is exemplified as a reflective display element, and the condenser lens 18 is exemplified as a condenser lens.

The above conditional expression (1) defines the operation of the condenser lens. As shown in FIG. 6A, the projected principal ray 51 (or 52) of the maximum angle of view and the projected principal ray 5 on the axis emitted from the display panel 12 which is a reflective display element.
When 0 is parallel, that is, when θ is 0, the condenser lens 1
8 causes the display panel 12 to be illuminated telecentrically. However, in the case of using a reflective display element in this way, the light beam passes twice through the condenser lens having the same function. Of the pupil of the projection optical system can be at the same position as the exit pupil of the projection optical system, and the diameter of the conjugate image of the pupil becomes the same as the exit pupil diameter.

As in the present invention, FIG.
When arranging the second lens array indicated by, the pupil distance is too close to the display panel and the diameter is too small.
It will be very difficult. Further, when θ becomes negative, the diameter of the conjugate image of the pupil further decreases, which is not preferable. Therefore, when the angle θ shown in FIG. 6B is set to 0.5 degrees or more to break the telecentric illumination, the position of the conjugate image of the pupil is displayed on the display panel 1.
2 is preferable because it is possible to increase the diameter of the conjugate image of the pupil away from 2. Further, it is preferable that θ be 2 degrees or more, because a larger pupil conjugate image diameter can be created.

In the case where liquid crystal is used for the reflective display element, it is not preferable that a good polarization modulation characteristic cannot be obtained when the angle with the on-axis light beam is large. Further, when θ is 3.5 degrees or less, good polarization modulation characteristics can be obtained while suppressing the diameter of the second lens array.

Conditional expression (2) defines the deviation of the projection optical system from telecentricity. As shown in FIG. 6B, when the angle θ ′ formed between the projected principal ray 51 ′ (or 52 ′) having the maximum angle of view and the projected principal ray 50 on the axis, which is emitted from the condenser lens 18, becomes 3 degrees or less. As the projection optical system approaches telecentricity, it becomes difficult to correct aberrations,
It is not preferable because good optical performance cannot be obtained. Conversely, if θ ′ exceeds 13 degrees, it is difficult to secure a sufficient lens back, and it is not preferable because a polarizing beam splitter, a dichroic mirror, and the like cannot be arranged.

A dichroic mirror is generally used as the above-described color combining mirror of the projection optical system and the color separation mirror of the illumination optical system, and this is, as schematically shown in FIG. It has a configuration in which a joint portion 43 is provided by laminating 41 and 42. The joint 43 is
A slight air gap may be used. Here, the two flat glass plates have the same thickness, and a dichroic coat is applied to one of the surfaces facing each other.

For example, in the figure, the surface 41a of the flat glass 41 is a dichroic coated surface. Also,
The surface 42a of the flat glass 42 does not need to be coated in the case of the above-mentioned bonding, but is coated with an anti-reflection coating when a slight air gap is used instead of the joint 43. Further, the outer surfaces 41b, 42b of the flat glass plates 41, 42 are antireflection coated surfaces.

In such a dichroic mirror, both the transmitted light and the reflected light pass through two glass plates, so that they are completely optically equivalent. Further, the above-mentioned slight air gap specifically means 1 mm or less, and if it is larger than that, the holding member of the dichroic mirror becomes large, which is not preferable.

By the way, if image information synthesizing means such as the above-mentioned color synthesizing mirror is provided in the lens back portion of the projection optical system,
The lens back is required by that much, and the burden on the projection optical system increases to secure the sufficient lens back. In other words, in order to have a sufficient lens back and satisfy good optical performance, it is necessary to add an aspheric surface or a lens to the projection optical system, which increases the cost and enlarges the whole. Not preferred. On the other hand, in order to perform color display by the projection optical system, it is preferable to have three display panels, and the wavelength ranges illuminated by the three display panels are set to blue, green, and red, respectively. By changing the gradation, the synthesized display can reproduce almost all colors.

Therefore, in this embodiment, as shown in FIG. 3 described above, the light beams G and R from the respective display panels 12 and 13 are transmitted between the projection optical system and the respective display panels 12 and 13, ie, the lens. The light flux and the light flux B, which are combined by the color combining mirror 21 disposed on the back portion, and the light fluxes G and R are combined.
Are composed by a color combining mirror 22 disposed inside the projection optical system.

In this way, the lens back for the color synthesis required for the projection optical system only needs to be provided for one image information synthesis unit, and the other image information synthesis unit is used for the projection optical system. Can be provided inside. Therefore, since it is not necessary to take a lens back more than necessary, it is not necessary to add an aspheric surface or a lens to the projection optical system, which is advantageous in terms of cost and size. However, such an image information synthesizing unit is not necessarily located anywhere within the projection optical system. This will be described later.

In addition, in general, when the distance between the image information synthesizing means such as a color synthesizing mirror and the display panel becomes large,
Correspondingly, the overlay shift of the projected image due to the positional shift or angular shift of the image information synthesizing means (convergence shift)
Becomes large. However, for blue, the relative luminous efficiency of humans is low, so that even if the convergence deviation of the projected image occurs due to this, the observer is relatively easy to tolerate. Accordingly, in the present embodiment, the light beam of blue color comes to the place where the image information synthesizing unit is farthest from the display panel, that is, between the color synthesizing mirror 22 and the display panel 14.

If the projection optical system is not telecentric and the incident angles of the on-axis light and the off-axis light incident on the color synthesizing mirror are largely different from each other, the characteristics of the color synthesizing mirror change, and the color unevenness on the projection screen changes. Occurs. Therefore, the thickness of the thin film coated thereon is changed depending on the position on the color synthesizing mirror to suppress the change in characteristics due to the incident angle. However, the thickness of the thin film cannot be freely controlled depending on the position, and the smaller the change in thickness, the easier it is to produce such a gradient thin film. That is, it is desirable that the difference between the incident angles of the on-axis light and the off-axis light with respect to the eccentric direction of the color combining mirror be smaller.

Further, for the same reason, the change in the thickness of the thin film can be suppressed as the incident positions of the principal ray and the axial ray having the maximum angle of view in the eccentric direction of the color synthesizing mirror are farther from the mirror.

In general, when passing through an obliquely flat glass plate, the focus position of the sagittal image and that of the meridional image are shifted according to the thickness and the inclination. In the present embodiment, as shown in the figure, for example, the light that has exited the display panel 12 is rotated around the Y axis and tilted before being incident on a projection screen (not shown).
Since the light passes through the two flat glass plates (color synthesizing mirrors 21 and 22), the focus positions of the sagittal image and the meridional image are greatly deviated.

Therefore, in order to correct this, the flat glass of the lens back (the polarizing beam splitter 1) is used.
5) is rotated and tilted around the X axis.
In this way, the eccentric directions of the color combining mirror and the polarizing beam splitter are different, and the thickness of each flat glass is optimized, so that the focus positions of the sagittal image and the meridional image can be made the same.

Furthermore, the eccentric directions of the color combining mirror and the polarizing beam splitter are orthogonal to each other because the Y axis and the X axis are the rotation axes, respectively. As described above, when the light passes through two inclined flat glass plates rotated in the orthogonal direction, the focus positions of the sagittal image and the meridional image can be aligned with both the on-axis light and the off-axis light. Conversely, if the eccentric directions are not orthogonal, it is difficult to align the focal positions.

The two color combining mirrors 21 and 22 are both rotated around the Y axis and tilted, but the directions of rotation are opposite to each other. This makes it possible to correct aberrations other than the above, which occur when light is incident on the inclined flat glass, that is, on-axis coma and one-sided blur.
Also, by decentering optical elements such as a lens group of the projection optical system (hereinafter referred to as a lens block), it is possible to correct on-axis coma and one-sided blur that could not be corrected above, and obtain good imaging performance. ing.

The construction data of the projection optical system according to the present invention is shown below. Examples listed below are:
This corresponds to the embodiment described above. In this embodiment, the radius of curvature of the surface having the surface number counted from the object side,
The graph shows the axial upper surface interval (shown here before decentering), the refractive index of the lens having the surface with respect to the d-line, and the Abbe number. The planes marked with * in the data indicate eccentric blocks.

<< Example >> Display panel size: 35 × 21 mm F number: 3.5 [Surface number] [Radius of curvature] [Shaft upper surface interval] [D-line refractive index] [Abbe number] Object (projection screen) ∞ 845.000000 r1 39.66906 0.950000 1.7545 51.57 r2 27.65747 12.783077 r3 54.98179 0.950000 1.5410 63.90 r4 aspherical surface 20.90005 * r5 ∞ 1.500000 1.5168 65.26 r6 ∞ * r7 62.93923 3.058765 1.8215 30.01 r8 170.11326 41.745.16 16.9814.124,1718. 5.853274 1.8270 26.47 r12 -66.71413 0.100000 r13 365.79827 3.579332 1.6226 57.53 r14 -77.84556 * r15 ∞ 1.500000 1.5168 65.26 r16 ∞ * r17 ∞ 2.287789 1.5168 65.26 r18 ∞ * r19 93.97493 3.542424 1.5168 65.26 r20 ∞ 2.0

Aspheric coefficient (4 surfaces) ε: 0.083523 A: 0.328407 × 10 ^-5 B: -0.718084 × 10 ^-8 C: 0.139205 × 10 ^-10 D: -0.234611 × 10 ^-13

Table 1 below shows the eccentric block data of the above-described embodiment. X, Y, and Z are the vertex coordinates of each block, and X rotation is the rotation of the X axis passing through the vertex of each block. The rotation angle as the axis and the Y rotation indicate the rotation angle with the Y axis passing through the apex of each block as the rotation axis.

[0050]

[Table 1]

FIG. 4 shows a distortion diagram of the embodiment described above. The solid line in the figure is a measured value, and the broken line is a calculated value. FIG. 5 shows a spot diagram of the embodiment. Attached to each point image, ...
The numbers in FIG. 3 correspond to the numbers on the grid of the distortion diagram, and indicate the respective positional relationships. From these figures, it can be seen that in the embodiment of the present invention, both the distortion performance and the point image performance are good.

Finally, Table 2 shows the values of θ and θ 'in the embodiment corresponding to the above conditional expression.

[Table 2]

Incidentally, the image display element referred to in the claims corresponds to the display panel in the embodiment, and the image information synthesizing means corresponds to the color synthesizing mirror.

[0054]

As described above, according to the present invention,
It is possible to provide an image projection apparatus having a projection optical system that achieves good imaging performance with a small number of lenses.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of an illumination optical system according to an embodiment of the present invention.

FIG. 2 is a side view of the vicinity of a mirror that folds a light beam.

FIG. 3 is a diagram schematically showing a configuration of a projection optical system according to the embodiment of the present invention.

FIG. 4 is a distortion diagram of the projection optical system according to the embodiment of the present invention.

FIG. 5 is a spot diagram of the projection optical system according to the embodiment of the present invention.

FIG. 6 is a schematic diagram showing an optical path near a reflective display element and a condenser lens.

FIG. 7 is an explanatory diagram schematically showing a configuration of a dichroic mirror.

[Explanation of symbols]

 Reference Signs List 1 light source 2 reflector 3 UVIR cut filter 4 first lens array 5 polarization separation block 6 second lens array 7,8 color separation mirror 9,10,11 mirror 12,13,14 display panel 15,16,17 polarizing beam splitter 18 , 19, 20 Condenser lens 21, 22 color combining mirror 23 Dummy glass 24, 25 Aperture 26 First group 27, 28 Second group 29, 30 Third group

Claims (2)

[Claims] A reflection type image display element, and a projection optical system for projecting image information of the image display element, wherein a condenser lens is provided between the image display element and the projection optical system. The projection optical system includes a front group, a stop, and a rear group in order from the object side, and satisfies the following conditional expressions: 0.5 <θ <53 3 <θ ′ <13, where θ : Angle formed between the projected principal ray of the maximum angle of view emitted from the reflective image display element and the projected principal ray on the axis θ ': The projected principal ray of the largest angle of view emitted from the condenser lens and the projected principal ray on the axis Angle. 2. A system comprising: at least two reflective image display elements; and a projection optical system for projecting image information of the image display elements, wherein a condenser lens is provided between the image display elements and the projection optical system. Wherein an image information synthesizing means for synthesizing image information of the image display element is provided inside the projection optical system, and the following conditional expression is satisfied: 0.5 <θ <5 3 <θ ′ <13, where θ is the angle formed between the projected principal ray of the maximum angle of view emitted from the reflective image display element and the axially projected principal ray θ ′: the principal of the maximum angle of view emitted from the condenser lens The angle between the ray and the projected principal ray on the axis.