JP2007025652A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-profile image display device capable of making a non-display part adjacent to a screen small. <P>SOLUTION: A projector 100 being the image display device which displays an image by transmitting light modulated in accordance with an image signal, through a screen 50 includes an optical engine part 10 for supplying the light modulated in accordance with the image signal, a plane mirror 30 being a first mirror for reflecting light from the optical engine part 10, and a curved surface mirror 40 being a second mirror which is formed like a curved surface and reflects light from the plane mirror 30 toward a screen 50. The optical engine part 10, the plane mirror 30, and the curved surface mirror 40 are so disposed that an optical path of light going from the optical engine part 10 to the plane mirror 30 and that of light going from the curved surface mirror 40 to the screen 50 cross each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an image display device, and more particularly to a technique of an image display device that displays an image by transmitting light corresponding to an image signal to a screen.

In order to display a large image with a thin configuration, an image display device that displays an image by transmitting light according to an image signal, for example, a rear projector, proposes a technology in which light is incident obliquely with respect to the screen. Has been. In order to display a large image with a thin configuration, the rear projector is desired to spread light over a wide range with a short optical path. If such a wide angle is to be realized only by the projection lens, the projection lens needs to be enlarged. A large projection lens is not suitable for use in a thin rear projector, and causes a cost increase. Therefore, conventionally, a technique has been proposed in which light corresponding to an image signal travels in a wide range using a curved mirror. As a technique using a curved mirror in an image display device, for example, there is one proposed in Patent Document 1.

JP-A 64-59226

An image display device is desired to make the non-display portion adjacent to the screen as small as possible in order to improve the design. By reducing the non-display portion adjacent to the screen, there is an advantage that a large image can be displayed even in a small housing. However, the above-mentioned Patent Document 1
In the configuration disclosed in the above, a space for disposing an optical engine unit and a mirror for supplying light according to an image signal needs to be secured, so that a non-display portion having a large width is formed below the screen. . Also in the case of other conventional configurations, it is very difficult to make the non-display portion small when the image display device is made thin, particularly when the optical engine unit is arranged near the screen. As described above, in the conventional technique, there arises a problem that it is difficult to simultaneously realize the thinning of the image display device and the reduction of the non-display portion adjacent to the screen. The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an image display apparatus that is thin and can reduce a non-display portion adjacent to a screen.

In order to solve the above-described problems and achieve the object, according to the present invention, an image display device that displays an image by transmitting light modulated according to an image signal to a screen,
An optical engine unit that supplies light modulated in accordance with an image signal, a first mirror that reflects light from the optical engine unit, and a curved surface, the light from the first mirror is directed toward the screen. A second mirror that reflects, the optical engine unit, the first mirror, and the second mirror, an optical path of light traveling from the optical engine unit to the first mirror, and a second mirror It is possible to provide an image display device that is arranged so that the light paths of light traveling from the screen to the screen cross each other.

The second mirror that reflects light in the direction of the screen is provided at a position facing the screen. The optical engine unit is preferably arranged in a different direction from the thickness direction of the housing in order to make the housing of the image display device thin. When the optical path of light traveling from the optical engine section to the first mirror and the optical path of light traveling from the second mirror to the screen cross each other, the optical engine section can be arranged away from the second mirror. It becomes. If the second mirror and the optical engine unit can be arranged apart from each other in the housing, the space inside the housing can be used effectively. Therefore, it is necessary to secure a large space around the screen, for example, below the screen. Disappears. If you can reduce the space around the screen like this,
It is possible to reduce the width of the non-display portion adjacent to the screen. Thereby, it is possible to obtain an image display device that is thin and capable of reducing the non-display portion adjacent to the screen.

According to a preferred aspect of the present invention, the screen is disposed along a plane including the first direction and the second direction substantially orthogonal to the first direction, the optical engine unit, and the first Mirror,
The second mirror is a direction in which light travels from the optical engine unit to the first mirror and a direction in which light travels from the second mirror to the screen in one of the first direction and the second direction. Are preferably arranged so as to be opposite to each other. For example, it is possible to adopt a configuration in which light travels downward from the optical engine unit to the first mirror and upward from the second mirror to the screen. In such a configuration, the optical engine unit, the first mirror, the second
In the configuration in which light travels in the order of the mirrors, the optical path of light traveling from the optical engine unit to the first mirror and the optical path of light traveling from the second mirror to the screen can intersect each other.

According to a preferred aspect of the present invention, the first mirror is provided in the vicinity of the outer edge portion of the screen, and the optical engine portion is opposite to the side on which the first mirror is provided with respect to the center position of the screen. It is desirable to be arranged on the side. For example, the second mirror can be arranged on the same side as the side on which the first mirror is provided with respect to the center position of the screen. In this case, the optical engine unit can be arranged at a position away from the first mirror and the second mirror. In addition, the optical engine unit can be arranged at a position that does not block the light traveling from the second mirror to the screen, and the space inside the housing that is likely to be a gap in the conventional configuration can be used effectively. Furthermore, since only the first mirror can be disposed in the vicinity of the outer edge portion of the screen, the non-display portion adjacent to the screen can be reduced.

Moreover, as a preferable aspect of the present invention, the optical engine unit and the first mirror are arranged such that light traveling from the second mirror to the screen passes between the optical engine unit and the first mirror. It is desirable. By adopting a configuration in which light that has passed between the optical engine unit and the first mirror is incident on the screen, the optical engine unit and the first mirror can be configured not to block light traveling to the screen. In addition, by arranging the optical engine unit in a space that tends to be a gap in the conventional configuration, the space inside the housing can be used effectively.

The optical path from the optical engine unit to the first mirror is ensured to have a sufficient length to pass light traveling from the second mirror to the screen. The light from the optical engine part is
It is also necessary to efficiently enter the mirror. For this reason, it is desirable that the projection optical system provided in the optical engine unit has a configuration that can sufficiently reduce the spread of light. By using a projection optical system capable of sufficiently reducing the spread of light, light can be efficiently incident on the second mirror even when the optical path from the optical engine unit to the second mirror is long. It is also possible to use a small projection optical system. Furthermore, the first mirror and the second mirror can be reduced in size by reducing the spread of light from the optical engine unit. By reducing the size of the projection optical system, the first mirror, and the second mirror, it is possible to save space and reduce costs.

Moreover, as a preferable aspect of the present invention, it is desirable that the optical engine unit, the first mirror, the second mirror, and the screen are all arranged so that their optical axes substantially coincide. By arranging the optical engine unit, the first mirror, the second mirror, and the screen so that their optical axes substantially coincide with each other, it is possible to adopt a normal coaxial system design method. As a result, it is possible to reduce the number of man-hours for designing the optical system and realize an optical system with less aberration.

Moreover, as a preferable aspect of the present invention, it is desirable that the second mirror has a substantially rotationally symmetric shape with respect to the optical axis. As a result, the optical engine unit, the first mirror, the second mirror, and the screen can all be arranged so that their optical axes substantially coincide.

As a preferred aspect of the present invention, the screen has an angle conversion unit that converts the angle of light from the second mirror, and the angle conversion unit is provided on the incident side of the light from the second mirror. The reflection optical unit has at least one of a reflection optical unit and a refractive optical unit provided on the light emission side from the second mirror, and the reflection optical unit reflects the light from the second mirror to make an angle Converted,
The refracting optical unit desirably converts the angle by refracting light from the second mirror. By using an angle conversion unit including a reflection optical unit and a refractive optical unit, it is possible to angle-convert light using the reflection optical unit and the refractive optical unit. For example, the angle conversion unit converts the angle of light using a reflection optical unit in a region where light having a large incident angle is incident, and converts the angle of light using a refractive optical unit in a region where light having a small incident angle is incident. It can be configured. In this case, in the region where light having a large incident angle is incident, the angle of the light is converted using the reflection optical unit, so that reflection of light at the interface on the incident side of the screen can be reduced. As a result, light having a wide range of incident angles can be efficiently advanced toward the viewer.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of a projector 100 that is an image display apparatus according to an embodiment of the present invention. The projector 100 is an image display device that displays an image by transmitting light modulated in accordance with an image signal to the screen 50, and is a so-called rear projector.
The optical engine unit 10 supplies light modulated according to the image signal. Optical engine unit 10
Is arranged at a position close to the ceiling surface 80 in the space inside the housing 60. Further, by arranging the optical engine unit 10 at a position away from the screen 50 to some extent, the light traveling from the curved mirror 40 to the screen 50 is not blocked by the optical engine unit 10.

FIG. 2 illustrates the configuration of the optical engine unit 10. The ultra-high pressure mercury lamp 101 serving as the light source unit includes red light (hereinafter referred to as “R light”) as the first color light, green light (hereinafter referred to as “G light”) as the second color light, and third light. Blue light which is colored light (hereinafter referred to as “B light”)
Supply light including. The integrator 102 makes the illuminance distribution of the light from the ultrahigh pressure mercury lamp 101 substantially uniform. The light having a uniform illuminance distribution is converted by the polarization conversion element 103 into polarized light having a specific vibration direction, for example, s-polarized light. The light converted into the s-polarized light is bent 90 degrees in the optical path by the reflection mirror 104 and then incident on the R light transmitting dichroic mirror 105R. The R light transmitting dichroic mirror 105R transmits R light and reflects G light and B light. The R light transmitted through the R light transmitting dichroic mirror 105R has its optical path bent by 90 degrees by the reflecting mirror 105 and is incident on the spatial light modulator 107R. Spatial light modulator 107R
Is a transmissive liquid crystal display device that modulates R light according to an image signal. Since the polarization direction of the light does not change even if it passes through the dichroic mirror, the R light incident on the spatial light modulator 107R remains as s-polarized light.

The s-polarized light incident on the spatial light modulator 107R is incident on a liquid crystal panel (not shown). In the liquid crystal panel, a liquid crystal layer for image display is sealed between two transparent substrates. The s-polarized light incident on the liquid crystal panel is converted into p-polarized light by modulation according to the image signal. Spatial light modulator 107R emits R light converted into p-polarized light by modulation. In this way, the R light modulated by the spatial light modulator 107R is incident on the cross dichroic prism 108 which is a color synthesis optical system.

The G light and B light reflected by the R light transmitting dichroic mirror 105R have their optical paths bent 90 degrees. G light and B light whose optical paths are bent are transmitted through a B light transmitting dichroic mirror 1.
Incident on 05G. The B light transmitting dichroic mirror 105G reflects G light and transmits B light. The G light reflected by the B light transmitting dichroic mirror 105G is converted into the spatial light modulator 1.
Incident on 07G. The spatial light modulator 107G is a transmissive liquid crystal display device that modulates G light according to an image signal. The s-polarized light incident on the spatial light modulator 107G is converted into p-polarized light by modulation in the liquid crystal panel. The spatial light modulator 107G emits G light converted into p-polarized light by modulation. In this way, the G light modulated by the spatial light modulator 107G enters the cross dichroic prism 108.

The B light transmitted through the B light transmitting dichroic mirror 105G is transmitted through two relay lenses 106.
Then, the light enters the spatial light modulator 107B via the two reflection mirrors 105. The spatial light modulator 107B is a transmissive liquid crystal display device that modulates B light according to an image signal. The reason why the B light passes through the relay lens 106 is that the optical path of the B light is longer than the optical paths of the R light and the G light. By using the relay lens 106, the B light transmitted through the B light transmitting dichroic mirror 105G can be directly guided to the spatial light modulator 107B.

The s-polarized light incident on the spatial light modulator 107B is converted into p-polarized light by modulation in the liquid crystal panel. The spatial light modulator 107B emits B light converted into p-polarized light by modulation. In this way, the B light modulated by the spatial light modulator 107B enters the cross dichroic prism 108 which is a color synthesis optical system. Spatial light modulators 107R, 10
7G and 107B may convert s-polarized light into p-polarized light by modulation, or may convert p-polarized light into s-polarized light.

The cross dichroic prism 108 which is a color synthesis optical system is configured by arranging two dichroic films 108a and 108b so as to be orthogonal to the X shape. The dichroic film 108a reflects B light and transmits R light and G light. The dichroic film 108b is R
Reflects light and transmits B light and G light. Thus, the cross dichroic prism 108
Synthesizes the R light, G light, and B light modulated by the spatial light modulators 107R, 107G, and 107B, respectively. The projection optical system 20 projects the light combined by the cross dichroic prism 108 in the direction of the plane mirror 30 (see FIG. 1).

Returning to FIG. 1, the plane mirror 30 is a first mirror that reflects light from the optical engine unit 10 toward the curved mirror 40. The plane mirror 30 is formed substantially flat. The plane mirror 30 is provided near the bottom surface 70 in the space inside the housing 60 and near the outer edge of the screen 50.

The curved mirror 40 is a second mirror that reflects light from the plane mirror 30 that is the first mirror toward the screen 50. The curved mirror 40 is formed in a curved surface shape. The curved mirror 40 has a function of widening the light from the plane mirror 30. By using the curved mirror 40, the light from the plane mirror 30 is enlarged and advanced to the screen 50. The curved mirror 40 also plays a role of correcting image distortion. By using the curved mirror 40, it is possible to display a large image with little distortion. Further, the curved mirror 40
By using the projection optical system 20, it becomes unnecessary to widen the angle.
Can be reduced in size. The curved mirror 40 may have any one of a spherical surface, an aspherical surface, and a free curved surface, and can be formed into a shape obtained by cutting a part of a cone, for example.

The curved mirror 40 can be configured by forming a reflective film on a substrate having a resin member or the like. As the reflective film, a highly reflective member layer, for example, a metal member layer such as aluminum, a dielectric multilayer film, or the like can be used. Further, a protective film having a transparent member may be formed on the reflective film. Details of the configuration of the curved mirror 40 are disclosed in, for example, JP-A-2002-26.
The configuration is the same as that of the projection mirror described in Japanese Patent No. 7823.

The curved mirror 40 is disposed between the bottom surface 70 of the space inside the housing 60 and the surface facing the surface on which the screen 50 is provided. The position where the curved mirror 40 is provided is a position facing the screen 50 and the plane mirror 30. The screen 50 is a transmissive screen that displays a projected image on a surface on the viewer side by transmitting light according to an image signal. The screen 50 is disposed on a predetermined surface of the housing 60 along an XY plane including a Y direction that is a first direction and an X direction that is a second direction substantially orthogonal to the first direction. ing.

The optical engine unit 10 and the plane mirror 30 are arranged so that light traveling from the curved mirror 40 to the screen 50 passes between the optical engine unit 10 and the plane mirror 30. By making the light incident on the screen 50 pass between the optical engine unit 10 and the flat mirror 30, the optical engine unit 10 and the flat mirror 30 do not block the light traveling to the screen 50. it can. In addition, by arranging the optical engine unit 10 in the space above the housing 60 that tends to be a gap in the conventional configuration, the space inside the housing 60 can be used effectively.

The optical path from the optical engine unit 10 to the flat mirror 30 is secured to have a sufficient length to allow light traveling from the curved mirror 40 to the screen 50 to pass therethrough. Since the projection optical system 20 capable of sufficiently reducing the spread of light until it enters the curved mirror 40 is used, the optical engine unit 1
Even when the optical path from 0 to the curved mirror 40 is long, light can be efficiently incident on the curved mirror 40. In addition, a small projection optical system 20 can be used. Furthermore, by reducing the spread of light from the optical engine unit 10, the plane mirror 30 and the curved mirror 40 can be reduced in size. By reducing the size of the projection optical system 20, the flat mirror 30, and the curved mirror 40, it is possible to save space and reduce costs.

Note that the configuration is not limited to the configuration in which the flat mirror 30 is used as the first mirror, and a curved mirror may be used. By using a curved mirror as the first mirror,
Part of the function of the curved mirror 40, which is the second mirror, can be shared by the first mirror. Furthermore, it is good also as a structure which uses the independent mirror provided with the function of a 1st mirror, and the function of a 2nd mirror. The first mirror and the second mirror may be provided with a layer having a lens function, for example, on the reflection surface, and may further have a function of converting the optical path.

FIG. 3 shows a cross-sectional configuration of the screen 50. The screen 50 includes a Fresnel lens 120 provided on a side on which light corresponding to an image signal is incident. The Fresnel lens 120 is an angle conversion unit that converts the angle of light corresponding to the image signal and emits the light toward the viewer. The Fresnel lens 120 includes a reflection optical unit 122 provided on the light incident side corresponding to the image signal, and a refractive optical unit 125 provided on the light emission side corresponding to the image signal. The Fresnel lens 120
The angle of light is converted using the reflective optical unit 122 and the refractive optical unit 125.

The reflective optical unit 122 is formed on the incident side surface of the substrate 127. The reflection optical unit 122 includes a plurality of reflection prisms 123 that perform angle conversion by reflecting light according to an image signal. The refractive optical unit 125 is formed on a surface on the emission side of the substrate 127. Refractive optical unit 12
Reference numeral 5 denotes a plurality of refraction prisms 12 that convert an angle by refracting light according to an image signal.
6.

A cover glass 121 for protecting the refractive optical unit 125 is provided on the emission side of the substrate 127 and the refractive optical unit 125. The screen 50 may be provided with a configuration other than the Fresnel lens 120 and the cover glass 121, for example, a microlens array for obtaining a good viewing angle, a diffusion plate for diffusing light, and the like. The curved mirror 40 (see FIG. 1) makes light incident on the screen 50 obliquely. The projector 100 has a screen 5
By adopting a configuration in which light corresponding to an image signal is obliquely incident on 0, the housing 60 can be made thin.

The reflection prism 123 and the refraction prism 126 are formed in a substantially concentric shape. The reflective optical unit 122 and the refractive optical unit 125 have a shape in which ring-shaped sections obtained by cutting out the convex surfaces of the convex lenses are arranged on the XY plane. The reflecting prism 123 and the refraction prism 126 are, for example, about 0.
Arranged at a pitch of 1 mm. The reflecting prism 123 and the refracting prism 126 are not limited to a configuration formed in a substantially concentric shape, and may be formed in an elliptical shape having a focal point at a substantially same position, for example.

FIG. 4 shows a cross-sectional configuration of a main part of a portion of the Fresnel lens 120 where the reflective optical unit 122 is formed. The reflective optical unit 122 is formed on a reference surface S1 that is a surface on the incident side of the substrate 127. In the cross-sectional configuration shown, the reflecting prism 123 includes a first surface 301 and a second surface 3.
02 and a triangular shape having three sides of the reference plane S1. The first surface 301 is a surface provided on the lower side of the reflecting prism 123. The second surface 302 is a surface provided on the upper side of the reflecting prism 123. The first surface 301 and the second surface 302 are joined at the ridge line portion 305.

The light traveling from the curved mirror 40 to the reflecting optical unit 122 is reflected on the first surface 3 of the reflecting prism 123.
01 is incident. The light incident on the first surface 301 travels inside the reflecting prism 123 and enters the second surface 302. The light incident on the second surface 302 is totally reflected by the second surface 302 and then travels toward the substrate 127. The reflecting prism 123 causes light corresponding to the image signal to travel to the viewer side by total reflection on the second surface 302. The first surface 301 and the second surface 302 are designed to angle-convert light corresponding to the image signal to the viewer side.

FIG. 5 shows a cross-sectional configuration of a main part of a portion of the Fresnel lens 120 where the refractive optical unit 125 is formed. The refractive optical unit 125 is formed on the surface S2 on the emission side of the substrate 127. The surface S2 is a surface parallel to the reference surface S1. In the cross-sectional configuration shown, the refraction prism 126.
Has a triangular shape having the first surface 401, the second surface 402, and the surface S2 as three sides. The first surface 401 is a surface provided on the lower side of the refractive prism 126. The second surface 402 is a surface provided on the upper side of the refractive prism 126. The first surface 401 and the second surface 402 are joined by a ridge line portion 405.

The light traveling from the curved mirror 40 toward the refractive optical unit 125 enters the refractive prism 126 from the surface S2. The light incident on the refractive prism 126 travels inside the refractive prism 126 and enters the second surface 402. The light incident on the second surface 402 is refracted by the second surface 402 and then travels to the viewer side. The second surface 402 is designed to angle-convert light corresponding to the image signal to the viewer side.

Returning to FIG. 3, the refractive optical unit 125 is provided on the side close to the center of the substantially concentric circle where the reflecting prism 123 and the refractive prism 126 are formed. The reflection optical unit 122 is provided on the side far from the center of the substantially concentric circle where the reflection prism 123 and the refraction prism 126 are formed. The incident angle of light incident on a position near the lower outer edge of the screen 50 is θ1, and the screen 5
An incident angle of light incident on a position near the upper outer edge of 0 is θ3. Further, the refractive optical unit 12
The incident angle of the light incident on the point P on the boundary between the region incident on 5 and the region incident on the reflective optical unit 122 is θ2.

Light having an incident angle of θ1 to θ2 is incident on the region where the refractive optical unit 125 is provided. Light having an incident angle of θ2 to θ3 is incident on the region where the reflection optical unit 122 is provided. Here, the incident angle is an angle formed between the normal line N of the reference plane S1 and the incident light beam. Reflective prism 123
In addition, the closer to the center of the substantially concentric circle where the refraction prism 126 is formed, the smaller the incident angle of light. For this reason, the relationship of θ1 <θ2 <θ3 is established. θ2 is 45, for example.
Degree. The reflective optical unit 122 is provided in a region where light having an incident angle of 45 degrees or more is incident. The refractive optical unit 125 is provided in a region where light having an incident angle of 45 degrees or less is incident.

For example, if the interface on the incident side of the screen 50 is formed to be substantially flat, light traveling at an angle greater than a predetermined angle with respect to the normal line N is reflected at the interface on the incident side of the screen 50. The reflection optical unit 122 reduces the reflection of light at the interface on the incident side of the screen 50 and efficiently guides the light to the viewer side. Therefore, in general, the refractive optical unit 125 is used for angle conversion of light incident at 0 to 60 degrees, and the reflective optical unit 1 is used for angle conversion of light incident at 45 to less than 90 degrees.
Each of 22 is suitable. In the projector 100 of the present invention, light in a wide angle range is incident on the screen 50 by widening the light with the curved mirror 40. Reflective optical unit 122
Since the angle of light is converted using the refracting optical unit 125, light having a wide range of incident angles can be efficiently advanced to the viewer side. Further, by allowing the Fresnel lens 120 to advance the light toward the viewer, the viewer can observe a bright image.

The Fresnel lens includes a region where light enters the reflective optical unit 122 and a refractive optical unit 125.
However, the present invention is not limited to the configuration in which the region where light enters is different. Like the Fresnel lens 620, which shows a cross-sectional configuration of the main part in FIG. 6, a region where light enters the reflective optical unit 122, and the refractive optical unit 12
It is good also as a structure with which the area | region in which light injects into 5 overlaps. Region A from the reflecting prism 123
The light traveling to R is angle-converted by the reflecting prism 123 and the refraction prism 126 provided in the area AR. In this case, even if the light is not sufficiently angle-converted by the reflecting prism 123, the light can be advanced toward the observer by using the refraction action by the refraction prism 126 together. Further, the Fresnel lens may be configured to provide only the reflective optical unit 122 without providing the refractive optical unit 125. Even when a Fresnel lens provided with only the reflective optical unit 122 is used, the projector 100 according to the present embodiment can be configured to be thin and have a small non-display unit as compared with a conventional projector using only the reflective optical unit 122. further,
The Fresnel lens may have a configuration in which only the refractive optical unit 125 is provided.

Returning to FIG. 1, the optical engine unit 10 is plus Y with respect to the center position O of the screen 50.
It is arranged on the upper side that is the direction. The optical engine unit 10 is provided so that the projection optical system 20 is slightly inclined from the vertically downward direction to the screen 50 side. In order to reduce the thickness of the housing 60, it is desirable that the optical engine unit 10 be disposed in a direction other than the X direction that is the thickness direction of the housing 60. For this reason, the housing | casing 60 can be made thin by setting it as the arrangement which inclines the optical engine part 10 a little from perpendicular downward like a present Example. The plane mirror 30 and the curved mirror 40 are arranged on the lower side in the minus Y direction with respect to the center position O. As described above, the optical engine unit 10 is disposed on the opposite side of the center position O of the screen 50 from the side on which the plane mirror 30 and the curved mirror 40 are provided.

In the vertical direction, the projector 100 causes light to travel downward from the optical engine unit 10 to the plane mirror 30, while traveling light upward from the curved mirror 40 to the screen 50. The optical engine unit 10, the plane mirror 30, and the curved mirror 40 are first
The direction in which light travels from the optical engine unit 10 to the plane mirror 30 and the direction in which light travels from the curved mirror 40 to the screen 50 are opposite to each other in the Y direction, which is The optical engine unit 10, the plane mirror 30, and the curved mirror 40 have an optical path of light traveling from the optical engine unit 10 to the planar mirror 30 and an optical path of light traveling from the curved mirror 40 to the screen 50. It is arranged to cross.

The optical path of the light traveling from the optical engine unit 10 to the plane mirror 30 and the optical path of the light traveling from the curved mirror 40 to the screen 50 are crossed with each other, so that the optical engine unit 10 is located above the center position O and the plane mirror 30. The curved mirror 40 can be disposed below the center position O. In this case, the optical engine unit 10 is separated from the plane mirror 30 and the curved mirror 40.
The housing 60 can be disposed at a position near the ceiling surface 80. By disposing the optical engine unit 10 at a position in the vicinity of the ceiling surface 80 of the housing 60, the curved mirror 40 to the screen 5.
It becomes possible to arrange the optical engine unit 10 at a position that does not block light traveling to zero. By arranging the optical engine unit 10 at a position near the ceiling surface 80 of the housing 60, the space existing in the upper portion of the housing 60 can be used effectively.

By arranging the optical engine unit 10 in the vicinity of the ceiling surface 80 away from the flat mirror 30 and the curved mirror 40, only the flat mirror 30 and the curved mirror 40 can be arranged in the vicinity of the bottom surface 70 of the housing 60. Compared to the conventional configuration in which the optical engine unit 10 is provided below the screen 50, the projector 100 according to the present invention can reduce the space below the screen 50 in the housing 60. Further, the curved mirror 40 is provided on the bottom surface 7 of the housing 60.
Since it is disposed between 0 and the surface facing the screen 50, only the plane mirror 30 can be disposed in the vicinity of the lower outer edge portion of the screen 50. It is only necessary to secure a space for arranging the plane mirror 30 below the screen 50. As described above, as shown by hatching in the front configuration of FIG. 7, the width of the non-display portion 700 adjacent to the screen 50 can be reduced, that is, the length in the Y direction can be reduced. Thereby, there is an effect that the non-display part 700 which is thin and adjacent to the screen 50 can be made small.

FIG. 8 is a diagram for explaining the arrangement of the components of the projector 100. The optical engine unit 10, the plane mirror 30, the curved mirror 40, and the screen 50 all form a so-called coaxial optical system in which the optical axes are substantially aligned. The curved mirror 40 and the screen 50 are provided with an optical axis A so that light is incident on the screen 50 at an angle.
It is provided at a position shifted upward from X. The projector 100 forms an image on a screen 50 provided by shifting from the optical axis AX. In FIG. 8, in order to represent the optical axis AX in a straight line, the illustration of the portion where the optical path is bent by the plane mirror 30 is omitted. Further, the optical engine unit 10 is illustrated only by the projection optical system 20.

By adopting a configuration in which the light from the projection optical system 20 is turned back to the curved mirror 40 using the plane mirror 30, the optical axis of the projection optical system 20 and the optical axis of the curved mirror 40 can be made substantially coincident. The curved mirror 40 has a substantially rotationally symmetric shape with respect to the optical axis AX. By making the curved mirror 40 substantially rotationally symmetric with respect to the optical axis AX, the optical axis of the curved mirror 40 and the optical axes of other configurations can be substantially matched.

Instead of the configuration using the plane mirror 30, the light from the projection optical system 20 is directly converted into the curved mirror 40.
A configuration in which the light is incident on the surface is also conceivable. In this case, the optical system including the projection optical system 20 and the curved mirror 40 constitutes a so-called decentered optical system in which individual optical axes are mismatched. When the decentered optical system is used, it becomes very difficult to correct the distortion of the image displayed on the screen 50. It is also difficult to reduce the occurrence of various aberrations. Further, since the curved mirror 40 has a shape having a free curved surface, it is very difficult to process.

The projector 100 according to the present embodiment employs a normal coaxial design method by arranging the optical engine unit 10, the plane mirror 30, the curved mirror 40, and the screen 50 so that the optical axes thereof are substantially coincident with each other. Is possible. As a result, it is possible to reduce the number of man-hours for designing the optical system and realize an optical system with less aberration. Further, since the curved mirror 40 has an axisymmetric aspherical shape, the processing can be made relatively easy.

In the projector 100 of the present embodiment, the configuration inside the housing 60 may be arranged upside down as it is. In this case, the optical engine unit 10 is disposed near the bottom surface 70, and the flat mirror 30 and the curved mirror 40 are disposed near the ceiling surface 80, respectively. Furthermore, the projector 100 according to the present embodiment may be arranged such that the configuration inside the housing 60 is tilted approximately 90 degrees to the right or left as it is. In this case, in the X direction, which is the second direction, the direction in which light travels from the optical engine unit 10 to the plane mirror 30 and the direction in which light travels from the curved mirror 40 to the screen 50 are opposite to each other. Configuration is arranged.

Here, the fact that it is possible to reduce the thickness and the non-display portion in the configuration of the projector 100 according to the present embodiment will be described by comparison with the configuration of the conventional image display device. 9 to 11 illustrate the configuration of a projector which is a conventional image display device. A projector 900 shown in FIG. 9 is characterized in that light is incident on the center position Q of the screen 950 substantially perpendicularly. The light from the optical engine unit 10 is reflected by the plane mirror 930 and then enters the screen 950. In order to reduce the thickness of the projector 900, it is conceivable to move the flat mirror 930 so that the angle formed by the screen 950 and the flat mirror 930 is small.

A projector 1000 shown in FIG. 10 is obtained by moving the plane mirror 930 so that the angle α formed by the screen 950 and the plane mirror 930 is reduced from the configuration of the projector 900 described above. In FIG. 10, it is assumed that light corresponding to the image signal is emitted from the point L.
A configuration of the projector 1000 is described. When the angle between the screen 950 and the plane mirror 930 is theoretically minimized, the angle α between the plane mirror 930 and the screen 950 is
Is 30 degrees. The angle range β of light emitted from the point L is 60 degrees. The lower limit value of the thickness t of the projector 1000 is obtained by the following formula, where h is the length of the screen 950 in the vertical direction.
t = h × tan 30 ° × cos ² 30 °

This means that the configuration of the projector 1000 has a limit to thinning. For example, when a 60-inch screen 950 is used, the theoretical value of the thickness t is 32 cm. In this case, the thickness t of the projector 1000 actually manufactured is approximately 40 cm. Furthermore, the projector 1000 needs to secure a space for arranging the optical engine under the screen 950 in order to arrange the optical engine unit at a position where the light reflected by the flat mirror 930 is not blocked. For this reason, a non-display portion for securing a space for storing the optical engine portion is formed under the screen 950. On the other hand, in order to make the non-display portion small from the configuration of the projector 1000, it is necessary to increase the angle α because it is necessary to dispose the optical engine at a position that does not block the light incident on the screen 950. As described above, in the conventional projectors 900 and 1000, it is very difficult to realize the reduction in thickness and the reduction of the non-display portion at the same time.

A projector 1100 shown in FIG. 11 is characterized in that light is incident on the center position Q of the screen 1150 obliquely from below. By making light incident obliquely on the center position Q of the screen 1150, the projector 1100 can be easily made thinner than the projectors 900 and 1000 by bending the optical path with the plane mirror 1130. On the other hand, also in the projector 1100, it is necessary to secure a space for disposing the optical engine unit under the screen 1150.

Further, since light in a wide angle range is incident on the screen 1150, the projector 1
100 also requires that the screen 1150 be provided with an angle conversion unit for causing light to travel to the viewer side. It is conceivable to use a reflection optical unit for the screen 1150 of the projector 1100. As described in the present embodiment, the reflecting optical unit is suitable for angle conversion of light incident at 45 degrees to less than 90 degrees. When the incident angle of light on the screen 1150 is limited to 45 degrees to less than 90 degrees, it is necessary to take a long optical path from the point L to the screen 1150.
If a plane mirror is further provided in addition to the plane mirror 1130 in order to take a long optical path from the point L to the screen 1150, the space under the screen 1150 will be further increased.

In the case of using the refractive optical unit in combination with the reflective optical unit as in the projector 100 of the present embodiment, it is not necessary to limit the incident angle of the light to the screen 1150, but a large projection optical for widening the light. It is necessary to use a system. If a large projection optical system is used, it is difficult to make the projector 1100 thin. As described above, not only the configuration disclosed in the above-mentioned Patent Document 1 but also other conventional techniques are used, it is difficult to simultaneously realize the thinning and the reduction of the non-display portion. Projector 100 of this embodiment
Compared to the conventional configuration described above, the non-display portion that is thin and adjacent to the screen can be made smaller.

FIG. 12 is a simulation of the optical path of the projection light in the projector 100 of the present invention. FIG. 13 shows the projection optical system 20 and the cross dichroic prism 108 in an enlarged manner. In FIG. 12 and FIG. 13, illustration of structures unnecessary for description is omitted. FIG.
Since the optical path can be secured as shown in FIG. 2, the projector 100 can be made thin and the optical engine unit can be accommodated in the space above the housing.

The projection optical system 20 can be composed of, for example, eight lenses including two aspheric lenses. Of the eight lenses shown in FIG. 13, the lens disposed closest to the cross dichroic prism 108 and the lens disposed second from the exit side are aspherical lenses. By causing the light from the cross dichroic prism 108 to be offset from the optical axis and to enter the projection optical system 20, the projection optical system 20 emits projection light shifted from the optical axis to a specific side.

14 and 15 are for explaining the performance of the projector 100. FIG. FIG.
The graph shown in FIG. 6 is an amplitude transfer function (MTF) expressed for a plurality of lights incident on different positions on the screen 50. The horizontal axis of the graph shown in FIG. 14 represents the spatial frequency of the stripes to be displayed, and the vertical axis represents the contrast transmission rate. The projector 100 is assumed to display an image from the spatial light modulators 107R, 107G, and 107B on the screen 50 at a magnification of 82 times. In this case, 50 cyc in the spatial light modulators 107R, 107G, and 107B
The spatial frequency of le / mm can be converted to 0.6 cycle / mm. Projector 100
Can achieve a contrast transmission rate of 0.7 or more for a spatial frequency of 0.6 cycle / mm. Thereby, it can be seen that contrast can be transmitted with high probability and high resolution can be realized.

The graph shown in FIG. 15 explains the distortion (distortion) of the image on the screen 50. Here, the distortion of the display image C1 with respect to the original image C0 is shown enlarged 30 times. The projector 100 according to the present invention displays a display image C1 with respect to the original image C0.
Can be set to 0.1% or less. Thus, the projector 100 can display a high-quality image with high resolution and little distortion. From the simulation results described above, it can be proved that the optical configuration of the projector 100 of the present invention is sufficiently realizable.

Although the projector 100 according to the present embodiment uses an ultrahigh pressure mercury lamp as the light source unit of the optical engine unit 10, the projector 100 is not limited to this. For example, a solid light emitting element such as a light emitting diode element (LED) may be used. Further, the projector is not limited to a so-called three-plate projector provided with three transmissive liquid crystal display devices, and may be a projector using a reflective liquid crystal display device or a projector using a tilt mirror device, for example. Further, the projector 100 may be a laser projector that scans a laser beam modulated according to an image signal. In the case of a laser projector, a laser light source that supplies laser light modulated in accordance with an image signal and a scanning optical system that scans light from the laser light source are used instead of the optical engine unit 10.

As described above, the image display device according to the present invention is useful when displaying a large image with a thin configuration.

1 is a diagram showing a schematic configuration of a projector according to an embodiment of the invention. The figure explaining the structure of an optical engine part. The figure which shows the cross-sectional structure of a screen. The figure which shows the principal part cross-section structure of a Fresnel lens. The figure which shows the principal part cross-section structure of a Fresnel lens. The figure which shows the principal part cross-section structure of another Fresnel lens. The figure which shows the front structure of a projector. The figure explaining the arrangement | positioning of each structure of a projector. FIG. 6 illustrates a configuration of a conventional projector. FIG. 6 illustrates a configuration of a conventional projector. FIG. 6 illustrates a configuration of a conventional projector. The figure which simulated the optical path of the projection light in this invention. The enlarged view of the part of a projection optical system and a cross dichroic prism. The figure explaining the performance of a projector. The figure explaining the performance of a projector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical engine part, 20 Projection optical system, 30 Plane mirror, 40 Curved surface mirror, 5
0 screen, 60 housing, 70 bottom surface, 80 ceiling surface, 100 projector, O
Center position, 101 super high pressure mercury lamp, 102 integrator, 103 polarization conversion element, 104 reflection mirror, 105R R light transmission dichroic mirror, 105GB light transmission dichroic mirror, 105 reflection mirror, 106 relay lens, 107R, 107
G, 107B spatial light modulator, 108 cross dichroic prism, 108a, 1
08b Dichroic film, 120 Fresnel lens, 121 Cover glass, 122
Reflective optical unit, 123 reflective prism, 125 refractive optical unit, 126 refractive prism, 12
7 substrate, N normal, S1 reference plane, S2 plane, 301 first plane, 302 second plane, 30
5 ridgeline part, 401 1st surface, 402 2nd surface, 405 ridgeline part, 620 Fresnel lens, 700 non-display part, AX optical axis, 900 projector, 930 plane mirror, 95
0 screen, 1000 projector, 1100 projector, 1130 plane mirror, 1150 screen

Claims (7)

An image display device that displays an image by transmitting light modulated in accordance with an image signal to a screen,
An optical engine unit for supplying light modulated in accordance with the image signal;
A first mirror that reflects light from the optical engine unit;
A second curved surface that reflects light from the first mirror toward the screen;
And having a mirror
The optical engine unit, the first mirror, and the second mirror are an optical path of light that travels from the optical engine unit to the first mirror, and travels from the second mirror to the screen. An image display device, wherein the image display devices are arranged so that the optical paths of light intersect each other. The screen is disposed along a plane including a first direction and a second direction substantially orthogonal to the first direction;
The optical engine unit, the first mirror, and the second mirror emit light from the optical engine unit to the first mirror in one of the first direction and the second direction. And the direction in which light travels from the second mirror to the screen,
The image display device according to claim 1, wherein the image display devices are arranged so as to be opposite to each other. The first mirror is provided in the vicinity of the outer edge of the screen,
The image display apparatus according to claim 1, wherein the optical engine unit is disposed on a side opposite to a side where the first mirror is provided with respect to a center position of the screen. The optical engine unit and the first mirror are arranged so that light traveling from the second mirror to the screen passes between the optical engine unit and the first mirror. The image display device according to any one of claims 1 to 3. The optical engine unit, the first mirror, the second mirror, and the screen are:
5. The image display device according to claim 1, wherein the image display devices are arranged so that the optical axes substantially coincide with each other. The image display apparatus according to claim 5, wherein the second mirror has a substantially rotationally symmetric shape with respect to the optical axis. The screen includes an angle conversion unit that converts the angle of light from the second mirror,
The angle conversion unit is at least one of a reflection optical unit provided on the light incident side from the second mirror and a refractive optical unit provided on the light emission side from the second mirror. Have
The reflection optical unit converts the angle by reflecting the light from the second mirror,
The image display apparatus according to claim 1, wherein the refractive optical unit converts an angle by refracting light from the second mirror.

Images