JPH10307277A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To laterally arrange an illumination optical system with respect to a projection optical system, to make a projected picture bright in a state where neither optical systems mechanically interfere each other and to reduce the capacity of a projection type display device by bending the optical axis of illuminating light in a specified direction. SOLUTION: The optical path of the illumination optical system is bent by a reflection mirror 15 put between a light source 1 located at the 1st focal position of an elliptical mirror 2 and a uniformizing lens 3 located at a 2nd focal position in the longitudinal direction (depth direction of paper surface) of a reflection type liquid crystal element 8, and is in a direction parallel with the paper surface, and made incident on the surface of the reflection type liquid crystal display element. In the case of viewing from a side surface in a breadth direction, the incident angle γ of a main light beam made incident on the display element 8 satisfies 2 deg.<=γ<=20 deg., and the outgoing angle δ of the main light beam outgoing therefrom satisfies 2 deg.<=δ<=20 deg.. An angle formed by an optical axis from the center of the light source 1 to the mirror 15 with the surface of the mirror 15 has the inclination of γ/2 on the surface in the breadth direction of the display element 8 and has the inclination of 15 deg. to 75 deg. on the plane in the longitudinal direction of the display element 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display apparatus using a transmission-scattering type reflection type display element.

[0002]

2. Description of the Related Art The purpose of a projection display device is to project an image on a screen separated by a predetermined distance, and to obtain a projection image larger than that of a direct-view display device. Previously, projection display devices using CRTs were often used,
2. Description of the Related Art In recent years, projection display devices using liquid crystal display elements have been widely used. A well-known twisted nematic (TN) type liquid crystal display element is used as a liquid crystal display element for the projection display device. However, the TN type liquid crystal display element is
Since it is essential to use a polarizing plate, there is a problem that light loss is large.

For this reason, it has been proposed to use a transmission-scattering type display element which does not need to use a polarizing plate as the light modulation means used in the projection type display device. As the display element having such a scattering property, a suspension display element, a laser writing mode liquid crystal element, a liquid crystal element of dynamic scattering (DSM) and the like have been conventionally known.

In a projection display device using these transmission-scattering type display elements, it is necessary to remove scattered light in order to control the state of light transmission by transmission scattering. Therefore, it is necessary to use a schlieren optical system having a stop mechanism.
This is described, for example, in SID Proceedings Vol.
18/2 2nd quarter 1977, 134-146
Page, "Projection system for light valves" and the like.

Recently, a liquid crystal / polymer composite device in which liquid crystal is dispersed in a polymer matrix (hereinafter referred to as a dispersion type liquid crystal device) has been developed. In this method, transmission scattering is controlled mainly by the inconsistency between the refractive indices of the polymer and the liquid crystal, and the transmission scattering can be controlled by the voltage application state. A projection display device using such a liquid crystal / polymer composite element is also known (Japanese Patent Laid-Open No. 5-1969).
23, JP-A-7-5419).

The dispersion type liquid crystal element of the transmission scattering type is a voltage control type element, has a high scattering performance and a high transmittance, and has a light absorption type TN liquid crystal element using a conventional polarizing plate or an S-type liquid crystal element.
Brighter display can be performed than the TN liquid crystal element.

In a transmission scattering type dispersion type liquid crystal element, when the reflection type is used, light passes through the liquid crystal layer in two round trip optical paths, so that the thickness of about half the transmission type is required to obtain the same scattering performance. The driving voltage can be reduced. Such a reflective projection display device is also described in the above-mentioned known document.
Specifically, projection display is performed by three reflective liquid crystal elements arranged so as to sandwich two dichroic mirror surfaces arranged in a delta type.

Further, a projection type display apparatus using a reflection type liquid crystal element of a transmission / scattering type, color-separating a white light source into three colors of RGB, and using three reflection type liquid crystal elements for modulating each color light is also known. Known (Japanese Patent Laid-Open No. 4-142528, No. 5)
FIG. 1 of JP-A-4-232917.

In each of these known examples, an elliptical mirror is used as a converging mirror of the illumination optical system, and the light emitted from the illumination optical system is collimated by one convex lens, and then three transmission scattering type light beams are emitted. To the reflection type liquid crystal element.

Here, the color separation / synthesis system is set at 45 ° to each other.
A dichroic prism that intersects with the convex lens for parallel light and the reflective liquid crystal element is used. In this case, a space is required between the projection lens and the parallelizing convex lens, and between the illumination optical system and the parallelizing convex lens, and the volume of the projection display device is increased.

In general, in the case of a projection type display device using a reflection type liquid crystal element, incident light and reflected light are not on the same optical axis,
Used with eccentricity. That is, the light is incident on the reflection surface of the reflection type liquid crystal element at a certain angle, and is reflected along a reflection optical axis different from the incident optical axis. Therefore, in order to use light without loss corresponding to the effective surface of the reflective liquid crystal element, the effective surface of the color separation / synthesis system and the convex lens for parallelizing light has a larger area than the reflective surface of the reflective liquid crystal element. I need.

Further, in a projection type display device using a reflection type liquid crystal element, in addition to the illumination optical system and the projection optical system being arranged on the same side with respect to the reflection type liquid crystal element, the projection type display device can be used as a desk top. If the projector is placed at a relatively low position near the floor,
Conversely, when the projector is placed near the ceiling, a function that can project light at a low position is required, so that an eccentric projection optical system is indispensable.

That is, when designing an optical system of a projection type display device using a reflection type liquid crystal element, an eccentric optical design is generally required for the projection optical system, and the center of the effective screen of the reflection type liquid crystal element is generally required. Since the position is apart from the optical axis of the projection lens, it is necessary to design the projection lens so that the design effective screen size is larger than the reflection screen type liquid crystal element.

In this case, the projection lens becomes larger than when the design is made coaxial with the center of the screen of the reflection type liquid crystal element, the optical system becomes complicated, and the volume, weight and cost tend to increase. In particular, in the case of a TN-type liquid crystal display element, it is necessary to increase the incident angle and the reflection angle in order to compensate for the decrease in the amount of light due to the polarizing plate. This requires a projection lens system (with a small F-number), which leads to a reduction in resolution, an increase in the number of optical lenses, a complication, and the like, resulting in a large and expensive projection display device.

[0015]

FIG. 4 is a side view of a conventional example of a projection type display device using a reflection type liquid crystal element. In addition to a dichroic mirror of a color separation optical system, an illumination optical system according to the present invention is used. 2 shows an example having no optical element for changing the optical path.

In FIG. 4, 1 is a light source, 2 is a condenser mirror, 3 is a uniforming lens, and 4 is an aperture stop.
To 4 constitute an illumination optical system. Reference numerals 5 and 6 denote dichroic mirrors for color separation / synthesis, 7 denotes a collimator lens, 8 denotes a reflection type liquid crystal element, and 9 denotes a reflection surface thereof. 10 is a projection lens barrel, 11 is an aperture stop, and 10 and 11 constitute a projection optical system.

Reference numeral 14 denotes a housing of the entire optical system, 16 denotes an optical axis of the reflective liquid crystal element, γ denotes an inclination angle (incident angle) of the optical axis 16 with respect to the optical axis of the illumination optical system, and δ denotes a projection optics with respect to the optical axis 16. The tilt angle (outgoing angle) with the optical axis of the system is shown. As in the case of FIG. 1, FIG. 4 shows only one reflective liquid crystal element, but two more reflective liquid crystal elements are arranged as shown in FIGS. .

In the case of the optical system shown in FIG. 4, in order to make the optical system brighter and smaller, the optical elements such as the condenser mirror 2, the uniformizing lens 3, the aperture stop 4, etc. of the illumination optical system, the mechanical components for holding them, and the projection As shown in FIG. 4, the projection lens of the optical system easily mechanically interfered (collimated).

To avoid this, it is necessary to increase the distance between the illumination optical system and the projection optical system to increase the incident angle γ of the illumination optical system or the emission angle δ of the projection optical system with respect to the optical axis of the reflective liquid crystal element. There is. However, in this case, since the width of the incoming / outgoing light beam when viewed from the side is increased, the required area of each element of the optical system is increased, and the optical system is further enlarged. In addition, when a transmission-scattering type reflection type liquid crystal element is used, there is a problem that as γ or δ increases, the excellent transmission / scattering effect of the transmission-scattering type liquid crystal display element decreases as described above. . On the other hand, in order to avoid this, if a part of an optical element such as a reflecting mirror of an illumination optical system that causes mechanical interference is cut off, the number of illumination light beams is reduced, and the brightness is reduced.

As described above, various proposals have been made for a projection type display device using a reflection type liquid crystal element. However, in particular, the incident angle / reflection angle on the surface of the liquid crystal optical element is not increased.
In addition, there has been a demand for a small and simple projection display device that does not cause mechanical interference between the illumination optical system and the projection optical system and projects the image of the reflective liquid crystal element on the screen brightly.

[0021]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an illumination optical system provided with a light source and a condensing mirror; a transmission-scattering-type reflective display element; In a projection display device provided with a color separation / synthesis optical system and a projection optical system, an eccentric imaging unit is disposed in an optical path between the illumination optical system and the projection optical system, and the light is reflected when viewed from the lateral side. Angle γ of the principal ray incident on the display device is 2 ° ≦ γ ≦
20 °, the emission angle δ of the principal ray emitted from the reflective display element satisfies 2 ° ≦ δ ≦ 20 °, and has a function to bend the optical path between the condenser mirror and the color separation / synthesis optical system. A reflecting mirror is disposed, and an angle formed between an optical axis from the center of the light source to the reflecting mirror and a surface of the reflecting mirror has a slope of γ / 2 in a plane in a short-side direction of the display element, and a display is performed. There is provided a projection display device characterized by having an inclination of 15 to 75 ° in a plane in the longitudinal direction of the element.

Also, in a projection type display apparatus provided with an illumination optical system provided with a light source and a condenser mirror, a transmission / scattering type reflection type display element, a color separation / synthesis optical system, and a projection optical system. The longitudinal direction of the reflective display element is arranged substantially parallel to the bottom surface of the projection display device, the reflecting mirror and the illumination optical system are arranged above or below the projection optical system, and the optical axis of the projection optical system and the illumination optical system are arranged. The optical axes of the system are substantially parallel to the bottom surface of the projection display device, and when viewed from the bottom surface, both optical axes are 30 to
It is arranged so as to intersect at an angle of 150 °, and the reflecting mirror of the illumination optical system has an inclination of γ / 2 with respect to the optical axis of the illumination optical system when viewed from the side, and the illumination when viewed from the bottom. The light having an inclination of 15 to 75 ° with respect to the optical axis of the optical system, the light reflected by the reflector of the illumination optical system is incident on the reflective display element at an incident angle of 2 ° ≦ γ ≦ 20 °, A projection type display device is provided which emits light from a display element at an emission angle of 2 ° ≦ δ ≦ 20 ° and is projected by a projection optical system.

According to the present invention, the illumination optical system is laterally arranged by bending the optical axis of the illumination light, and the illumination optical system and the projection optical system do not cause mechanical interference, and the image of the reflection type liquid crystal element is brightened. A small and simple projection display device that projects onto a screen is obtained.

[0024]

1 and 2 show a side view and a plan view, respectively, of a projection type display device according to the present invention. For simplicity, FIG. 2 shows the projection lens barrel of the projection optical system with a dotted line,
The display is overlapped with the illumination optical system.

In FIGS. 1 and 2, reference numeral 1 denotes a light source, 2 denotes a condenser mirror, 3 denotes a uniformizing lens, and 4 denotes an aperture stop. These components 1 to 4 constitute an illumination optical system. 5 and 6 are dichroic mirrors for color separation / synthesis, 7 is a collimator lens,
8, 17 and 18 are reflection type liquid crystal elements, and 9 is its reflection surface. 10 is a projection lens barrel, 11 is an aperture stop, and 1
0 and 11 constitute a projection optical system.

Reference numeral 12 denotes a reference line on the reflection mirror surface in the longitudinal plane of the reflection type liquid crystal element, reference numeral 13 denotes a reference line on the reflection mirror surface in the short side surface of the reflection type liquid crystal element, and reference numeral 14 denotes the entire optical system. A housing, 15 is a reflecting mirror for bending the optical axis of the illumination optical system, 16 is an optical axis of the reflective liquid crystal element, and 19 is an optical axis of the illumination optical system.

Γ is the inclination angle (incident angle) of the illumination optical system with respect to the optical axis 16 with respect to the optical axis, δ is the inclination angle (emission angle) of the projection optical system with respect to the optical axis 16, and ω is the inclination angle of the reflection type liquid crystal element. The reference line 12 on the reflecting mirror surface in the longitudinal plane and the optical axis 1 of the illumination optical system
The angle .theta. Indicates the angle between the reference line 13 on the reflecting mirror surface and the optical axis 19 of the illumination optical system in the lateral plane of the reflective liquid crystal element.

The optical axis 16 in the present invention is a line perpendicular to the reflection surface 9 of the reflection type liquid crystal element 8 arranged at the rearmost side. Actually, the light beam from the illumination optical system and the light beam reflected by the reflection surface of the reflective liquid crystal element and returned to the projection optical system are transmitted through the collimator lens 7 and refracted. The virtual reflection point at the time of doing is determined. A line passing through this reflection point and perpendicular to the reflection surface 9 of the reflection type liquid crystal element 8 disposed on the rearmost side is defined as an optical axis 1
6, and the inclination angle (incident angle) with respect to the optical axis of the illumination optical system is γ, and the inclination angle (emission angle) with the optical axis of the projection optical system is δ. Therefore, if the shape of the collimator lens 7 of the reflection type liquid crystal element 8 is vertically symmetric when viewed from the plane of FIG.
This incident angle γ = emission angle δ.

The reference lines 12, 13 of the reflecting mirror in the present invention
Will be described. In the present invention, the longitudinal direction of the reflective liquid crystal element 8 is arranged in parallel with the reference bottom surface (usually, the case bottom surface) of the projection display device. A plane parallel to the longitudinal direction of the reflective liquid crystal element 8 and parallel to the optical axis 16 of the reflective liquid crystal element 8 is defined as an optical axis parallel plane.

On the other hand, the point where the optical axis 19 of the light beam from the projection optical system reaches the reflecting mirror 15 is defined as a reflection point. A plane parallel to the optical axis passing through the reflection point is determined, and an intersection line between the plane parallel to the optical axis and the boundary surface of the reflecting mirror is defined as a reference line 12 in the longitudinal plane. The angle between the reference line 12 and the optical axis 19 is ω. A line orthogonal to the reference line 12 on the boundary surface of the reflecting mirror 15 is defined as a reference line 13, and an angle between the reference line 12 and the optical axis 19 is defined as θ.

In the example of FIGS. 1 and 2, the reflective liquid crystal element 8
Is perpendicular to the reference bottom surface of the projection display device,
The optical axis 16 is arranged parallel to the reference bottom surface. Therefore, the reference line 13 shown in FIG. 1 is inclined by θ = γ / 2 from a line perpendicular to the reference bottom surface.

FIG. 3 is a front view of the projection type display device shown in FIGS. For the sake of simplicity, the illumination optical system, the reflecting mirror, and the projection lens barrel are shown by solid lines and overlapped, and members arranged behind some of them are omitted. In an actual arrangement, the reflection mirror 15 is arranged so as to be partially hidden by the shadow of the projection lens barrel 10. FIG.
2 shows that the concave lens 20 is arranged in the illumination optical system.

In the present invention, in order to reduce the volume of the entire projection type display device, it is preferable that the short-side direction of the reflection type liquid crystal element be the vertical direction in FIG. This arrangement is also advantageous in terms of the size of the dichroic mirror.

In FIGS. 1, 2 and 3, an elliptical mirror is used as a reflector of the light source of the liquid crystal illumination optical system, but the size of the parabolic mirror as the reflector of the light source is substantially different from that of the elliptical mirror. Absent. Further, in the case of a parabolic mirror, the light flux of the light source is almost parallel light, so that a light flux having a size equal to or larger than the effective screen size of the reflection type liquid crystal element is required as it is. In this case, it is necessary to converge a light beam from a convex lens or the like immediately after the parabolic mirror to make it smaller.

In FIG. 1, the optical path of the illumination optical system is composed of a light source of the illumination optical system at the first focal position of the elliptical mirror in the longitudinal direction of the reflective liquid crystal element (the depth direction of the plane of FIG. 1) and its second light source.
The light is bent by a reflecting mirror placed between the lens and the light source equalizing lens placed at the focal position, becomes a direction parallel to the paper surface, and enters the reflective liquid crystal element surface.

Here, since the light source has a certain size,
The conjugate image of the light source is scattered to a certain size around the second focal position, and the conjugate light source image having uniform brightness having the size of the aperture stop is formed by the aperture stop and the uniformizing lens placed here. Has become. FIG. 2 is a plan view of this relationship as viewed from above in FIG.

Further, the angle formed by the optical axis from the center of the light source of the illumination optical system to the reflecting mirror and the reference line of the reflecting mirror is θ in a plane including the lateral direction of the reflective liquid crystal element (in the plane of FIG. 1). In addition, assuming that ω is in a plane including the longitudinal direction of the reflective liquid crystal element (in the plane of FIG. 2), the inclination of the reflecting mirror is determined by the values of θ and ω.

In the side view of FIG. 1, θ is set to a half of γ of the optical axis of the illumination optical system which enters the central point of incidence of the reflection type liquid crystal element, that is, γ / 2. Accordingly, the optical axis of the illumination optical system becomes γ with respect to the reflective liquid crystal element surface after being bent by the reflecting mirror, and the optical axes of the light source and the elliptical mirror before bending are 0 °, that is, Can be made parallel to the normal of the reflection surface of the liquid crystal device.

In a projection type display device having a reflection type liquid crystal element, since the direction parallel to the longitudinal direction of the reflection type liquid crystal element is generally a horizontal plane, the light source of the illumination optical system and the optical axis of the elliptical mirror are: As shown in FIG. 3, the projection type display device can be made parallel to a stable horizontal plane, and the structure becomes easier to manufacture.

Further, in FIG.
The optical axis of the light source of the illumination optical system and the optical axis of the elliptical mirror before being incident on the reflecting mirror are within the plane parallel to the longitudinal direction of the reflective liquid crystal element, Can be bent in the range of 30 to 150 °.

That is, a reflecting mirror is inserted between the illumination optical system and the reflective liquid crystal element, and the angle between the optical axis from the center of the light source of the illumination optical system to the reflecting mirror and the angle of the reflecting mirror is adjusted. It has an inclination of γ / 2 in the plane in the lateral direction, and 15 to 75 ° in the plane in the longitudinal direction of the reflective liquid crystal element.
By having the inclination of, the optical path of the illumination light beam can be bent, and the position of the light source and the reflector of the illumination optical system can be changed to a position away from a position where mechanical interference with the projection optical system is likely to occur, and The angle of the optical axis can be made parallel to a stable horizontal plane.

By satisfying such a condition range,
It is possible to solve the problem of avoiding mechanical interference between the illumination optical system and the projection optical system while achieving both miniaturization and brightness, and to realize a small, lightweight, and inexpensive reflective projection display device.

When the optical axis of the illumination optical system is bent by a reflecting mirror, an arrangement in which the optical axis of the illumination optical system in FIG. 1 is in the vertical direction in the figure can be considered.
The end of the illumination optical system protrudes greatly, and the volume of the projection display device becomes considerably large as compared with the arrangement of the present invention. In this case, the adjustment of the reflecting mirror is troublesome.

[0044]

【Example】

"Example 1" The arrangement was such that γ = 10 ° in FIG. 1 and ω = 45 ° in FIG. In this case, the tilt angle θ of the reflecting mirror is θ = γ / 2 = 5 °, and the light source of the illumination optical system and the optical axis of the elliptical mirror before entering the reflecting mirror are in a plane parallel to the longitudinal direction of the reflective liquid crystal element. And it could be oriented at 90 ° with respect to the optical axis of the illumination optical system after reflection in that plane.

As a result, the light source and the elliptical mirror of the illumination optical system have stable optical axes parallel to the horizontal plane of the bottom surface of the case of the projection display device, and are unlikely to cause mechanical interference with the projection optical system. Optical arrangement in a perpendicular direction was achieved.

When three dispersion type liquid crystal elements using an active matrix substrate were used as the reflection type liquid crystal elements and projection display was performed, brighter display was obtained than when the TN type liquid crystal display element was used.

Example 2 In FIG. 1, γ = 15 ° and
In FIG. 2, they are arranged so that ω = 30 °. In this case, the inclination angle θ of the reflecting mirror is θ = γ / 2 = 7.5 °, and the optical axes of the light source and the elliptical mirror of the illumination optical system before entering the reflecting mirror are parallel to the longitudinal direction of the reflective liquid crystal element. The optical axis of the illumination optical system after being reflected in the plane and 60
° direction.

As a result, the light source and the elliptical mirror of the illumination optical system are in a stable plane whose optical axis is parallel to the horizontal plane of the bottom surface of the case of the projection display device, and in the plane of FIG. The position was closer to the liquid crystal element, and a smaller optical arrangement having a smaller width in this direction was achieved.

Also in this example, three dispersion type liquid crystal elements using an active matrix substrate were used as the reflection type liquid crystal elements, and projection display was performed. As a result, a brighter display was obtained than when a TN type liquid crystal display element was used. Obtained.

[0050]

According to the present invention, the illumination optical system is arranged laterally with respect to the projection optical system by bending the optical axis of the illumination light in a specific direction, so that the illumination optical system and the projection optical system are mechanically arranged. It does not cause interference. Thereby, the projection image of the projection display device can be brightened, and the volume of the projection display device can be reduced.

In addition, despite the eccentric system, the light source optical system only has to be disposed parallel to the bottom surface, so that the assembly is easy and the angle adjustment for the eccentricity of the reflecting mirror can be adjusted by θ.
= Γ / 2, and the other angle ω is also determined from the optical axis of the illumination optical system, so that adjustment is easy and assembly productivity is good.

Further, if a dispersion type liquid crystal element having a high-speed response and excellent transmission scattering performance is used and used in a reflection type, T
Since the drawback of a high voltage can be suppressed as compared with the N-type liquid crystal element, and the active matrix substrate itself may have a low withstand voltage, there is an advantage that it is easy to manufacture a high-performance transmission-scattering reflective liquid crystal element. In addition, the present invention can be applied to various applications as long as the effect is not impaired.

[Brief description of the drawings]

FIG. 1 is a side view of a basic configuration of an entire optical system according to the present invention.

FIG. 2 is a plan view of a basic configuration of the entire optical system of the present invention.

FIG. 3 is a front view of the basic configuration of the entire optical system of the present invention.

FIG. 4 is a side view of a basic configuration of the entire optical system of a conventional example.

[Explanation of symbols]

1: Light source 2: Condensing reflector 3: Uniform lens 4: Aperture stop 5, 6: Dichroic mirror for color separation / synthesis 7: Collimator lens 8, 17, 18: Reflective liquid crystal element 9: Reflecting surface 10: Projection lens Lens tube 11: Aperture stop 12: Reference line on reflective mirror surface in longitudinal plane of reflective liquid crystal element 13: Reference line on reflective mirror surface in lateral direction plane of reflective liquid crystal element 14: Enclosure of entire optical system Body 15: Reflecting mirror 16: Optical axis of reflective liquid crystal element 19: Optical axis of illumination optical system 20: Concave lens γ: Tilt angle between optical axis of reflective liquid crystal element and optical axis of illumination optical system δ: Reflective liquid crystal element Angle between the optical axis of the projection optical system and the optical axis of the projection optical system θ: the angle between the reference line on the reflecting mirror surface and the optical axis of the illumination optical system in the longitudinal plane of the reflection type liquid crystal element ω: short side of the reflection type liquid crystal element Angle between the reference line on the mirror surface in the direction plane and the optical axis of the illumination optical system

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03B 33/12 G03B 33/12

Claims (2)

[Claims] An illumination optical system including a light source and a condensing mirror, a transmission-scattering reflective display element, a color separation / synthesis optical system, and a projection optical system are provided. An eccentric imaging means is arranged in the optical path between the illumination optical system and the projection optical system, and the incident angle γ of the principal ray incident on the reflective display element as viewed from the lateral side is 2 ° ≦ γ ≦ 20. °, the emission angle δ of the chief ray emitted from the reflective display element satisfies 2 ° ≦ δ ≦ 20 °, and a reflection having a function of bending an optical path between the condenser mirror and the color separation / synthesis optical system. A mirror is disposed, and an angle formed by an optical axis from the center of the light source to the reflecting mirror and a surface of the reflecting mirror has a slope of γ / 2 in a plane in a lateral direction of the display element, and In the longitudinal plane of
A projection display device having an inclination of 5 to 75 [deg.]. 2. A projection type display apparatus comprising: an illumination optical system provided with a light source and a condenser mirror; a transmission / scattering type reflection type display element; a color separation / synthesis optical system; and a projection optical system. The longitudinal direction of the reflective display element is arranged substantially parallel to the bottom surface of the projection display device, the reflecting mirror and the illumination optical system are arranged above or below the projection optical system, and the optical axis of the projection optical system and the illumination optical system are arranged. The optical axes of the system are substantially parallel to the bottom surface of the projection display device, and when viewed from the bottom surface, both optical axes are 30 to 1
It is arranged so as to intersect at an angle of 50 °, and the reflecting mirror of the illumination optical system has an inclination of γ / 2 with respect to the optical axis of the illumination optical system when viewed from the side, and the illumination when viewed from the bottom. The light having an inclination of 15 to 75 ° with respect to the optical axis of the optical system, the light reflected by the reflector of the illumination optical system is incident on the reflective display element at an incident angle of 2 ° ≦ γ ≦ 20 °, A projection-type display device, wherein light is emitted from a display element at an emission angle of 2 ° ≦ δ ≦ 20 ° and is projected by a projection optical system.