JP2004029238A - Image projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image projector which resolves problems of aberrations, vignetting, etc. without degrading the transmission efficiency of light from a light source and projects an original image on a screen faithfully to the original image. <P>SOLUTION: An image projector 10 for projecting images on the screen is provided with a display panel 210 for displaying images thereon, a light source 112 for irradiating the display panel 210, a projection lens 182 which is arranged at an angle to a main plane 212 of the display panel 210 and projects images displayed on the display panel 210, on the screen, and a first deflecting means which is provided between the display panel 210 and the projection lens 182 and deflects light from the light source 112. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image projection device that emits light from a light source and projects an image displayed on a display panel onto a screen.
[0002]
[Prior art]
The front projection type image projection apparatus enlarges an image displayed on a display panel on a reflection type screen and displays the image. However, when the image displayed on the display panel is projected perpendicularly to the reflective screen, there is a problem that the image projected on the reflective screen is distorted into a trapezoidal shape. As a method of solving this problem, a method of correcting distortion of an image projected on a reflective screen by tilting an optical axis of a light source emitted from the light source with respect to a main plane of the reflective screen has been conventionally known. Have been.
[0003]
Also, in a rear projection type image projection device, a technology for reducing the depth dimension of the device by inclining a display panel and a projection lens with respect to a transmission screen is known.
[0004]
[Problems to be solved by the invention]
However, when the optical axis from the light source is inclined with respect to the main plane of the screen as in the above-described image projection device, the light incident surface of the display panel is arranged to be inclined with respect to the optical axis of the light source. Therefore, there is a problem that a part of the light beam incident on the display panel from the light source is reflected on the light incident surface of the display panel, and the transmission efficiency in the display panel is reduced.
[0005]
As a method for solving this problem, for example, Japanese Patent Application Laid-Open No. Hei 6-289354 proposes a display panel having alternately vertical and horizontal surfaces with respect to the light source optical axis. However, the production of such a display panel is not easy and is very expensive.
[0006]
The present invention has been made in view of the above problems, and an image capable of accurately projecting an original image on a screen while solving the problem of trapezoidal distortion and efficiently using light from a light source. It is an object to provide a projection device.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is an image projection device that irradiates a light source light from a light source and projects an image displayed on a display panel onto a screen. A projection lens that is arranged to be inclined with respect to the projection panel and projects an image displayed on the display panel onto the screen, and is provided between the display panel and the projection lens, and emits a light beam of the light source light from the projection lens. A first deflecting means for deflecting in a direction perpendicular to the main plane.
[0008]
According to the first aspect of the invention, the first deflecting means provided between the display panel and the projection lens causes the light beam of the light source light, which is perpendicularly incident on the main plane of the display panel, to be incident on the incident surface of the projection lens. It can be refracted in a direction perpendicular to the direction. Thereby, it is possible to avoid problems such as aberration and vignetting caused by oblique incidence of transmitted light on the incident surface of the projection lens. Therefore, by arranging the display panel at an angle to the projection lens, it is possible to optically correct trapezoidal distortion and efficiently project an image on the screen without lowering the transmission efficiency of light from the light source.
[0009]
According to a second aspect of the present invention, in the image projection device according to the first aspect, the first deflecting unit deflects a light beam of the light source light in a direction perpendicular to a main plane of the projection lens. Characterized in that it is a first prism having
[0010]
According to the second aspect of the present invention, the deflecting surface of the first prism is provided so as to deflect the light beam of the light source light in a direction perpendicular to the main plane of the projection lens. It is incident perpendicular to the light. As a result, it is possible to avoid problems such as aberration and vignetting in the projection lens and decrease in luminance of an image projected on the screen. Therefore, the original image can be projected on the screen by efficiently using the light source light while eliminating the trapezoidal distortion.
[0011]
According to a third aspect of the present invention, in the image projection device according to the first or second aspect, the first deflecting unit is provided perpendicular to an optical axis of the light source light passing through the display panel. And a first prism having an incident surface.
[0012]
According to the third aspect of the invention, since the incident surface of the first prism is provided perpendicular to the optical axis of the light source light passing through the display panel, the light source light is reflected by the first prism. This can be avoided, and the transmission efficiency can be prevented from lowering due to the thinner light beam incident on the first prism. Therefore, the original image can be projected on the screen by efficiently using the light source light while eliminating the trapezoidal distortion.
[0013]
According to a fourth aspect of the present invention, in the image projection device according to the second or third aspect, the first prism has a vertex angle determined according to a wavelength of the light source light. And
[0014]
According to the fourth aspect of the present invention, the vertex angle of the first prism is determined according to the wavelength of the light source light. Accordingly, it is possible to avoid a color shift in an image projected on the screen due to a shift between a light beam of transmitted light transmitted through the prism and an optical axis of the projection lens. Good reproducibility can be maintained.
[0015]
According to a fifth aspect of the present invention, in the image projection device according to any one of the first to fourth aspects, the light source is provided between the light source and the display panel, and is perpendicular to the projection lens. The display device further includes a second deflecting unit that deflects the light beam in a direction perpendicular to the main plane of the display panel.
[0016]
According to the fifth aspect of the invention, the light source light can be deflected twice by the first deflecting means and the second deflecting means. In other words, light from the light source radiated perpendicularly to the projection lens can be deflected in a direction perpendicular to the main plane of the display panel, so that trapezoidal distortion is eliminated and light from the light source is efficiently used. be able to. Furthermore, since the light source light can be emitted in a direction perpendicular to the projection lens, the size of the main body of the image projection device can be further reduced by arranging the light source at an appropriate place.
[0017]
According to a sixth aspect of the present invention, in the image projection apparatus according to the fifth aspect, the second deflecting unit deflects the light beam of the light source light in a direction perpendicular to a main plane of the display panel. Characterized in that it is a second prism having
[0018]
According to the sixth aspect of the present invention, the deflecting surface of the second prism is provided so as to deflect the light beam of the light source light in a direction perpendicular to the main plane of the display panel. It is incident perpendicular to the light. Thus, it is possible to prevent the light source light from being reflected on the display panel or the light flux incident on the display panel from becoming thinner, thereby preventing the transmission efficiency from being reduced. Therefore, the original image can be projected on the screen by efficiently using the light source light while eliminating the trapezoidal distortion.
[0019]
According to a seventh aspect of the present invention, in the image projection device according to the fifth or sixth aspect, the second deflecting unit has an incident surface provided perpendicular to an optical axis of the light source light. It is characterized by having two prisms.
[0020]
According to the seventh aspect of the present invention, the incident surface of the second prism is provided perpendicular to the optical axis of the light source light, so that the light source light is prevented from being reflected by the second prism, and It is possible to avoid a decrease in transmission efficiency due to a thinner light beam incident on the second prism. Therefore, the original image can be projected on the screen by efficiently using the light source light while eliminating the trapezoidal distortion.
[0021]
According to an eighth aspect of the present invention, in the image projection device according to the sixth or seventh aspect, the second prism has an apex angle of an angle determined according to a wavelength of the light source light. And
[0022]
According to the eighth aspect of the present invention, the angle of the vertex of the second prism is determined according to the wavelength of the light from the light source. Accordingly, it is possible to avoid the occurrence of color shift in the image projected on the screen due to the deviation of the light beam of the transmitted light transmitted through the second prism and the optical axis of the projection lens. Can maintain good color reproducibility.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The “projection lens side prism” and the “light source side prism” described in the embodiments of the invention are examples of the “first prism” and the “second prism”, respectively, in the claims. .
[0024]
(Embodiment 1)
FIG. 1 is a block diagram illustrating a configuration of an image projection device 10 according to the first embodiment of the present invention. The image projecting apparatus 10 mainly includes a light source unit 110 that irradiates white light, dichroic mirrors 130 and 132 that separate white light into light of RGB components, and a B component provided for each of RGB light beams. A projection system unit 200, a G component projection system unit 300, and an R component projection system unit 400; a cross prism 180 for color-combining RGB light beams; and a projection lens for projecting the color-combined light onto a screen (not shown). 182.
[0025]
The light source unit 110 includes an extra-high pressure mercury lamp 112 that emits white light, and an elliptical curved reflecting plate 114 that reflects the white light emitted by the extra high pressure mercury lamp 112. Note that a free-form surface reflection plate may be provided instead of the elliptical surface reflection plate 114.
[0026]
The light source light reflected by the elliptical curved reflection plate 114 is converted into light having uniform brightness in a certain range via a multi-lens (integrator) 120. Further, the deflecting plate 122 aligns the plane of polarization of the light source light passing through the multi-lens 120. The deflecting plate 122 may be a deflecting beam splitter or the like.
[0027]
Further, the condenser lens 124 condenses the light source light passing through the deflection plate 122. The mirror 126 refracts the light source light condensed by the condenser lens 124 and causes the light to enter the dichroic mirror 130. The dichroic mirrors 130 and 132 decompose the light from the light source into light of RGB components. The B component light separated by the dichroic mirror 130 is refracted by the mirror 134 and enters the B component projection system unit 200.
[0028]
The B component projection system unit 200 includes a collimator lens 202, a display panel 210, and a projection lens side prism 220. The display panel 210 may be, for example, a transmission type liquid crystal light valve. The display panel 210 is arranged obliquely with respect to the projection lens 182 to eliminate trapezoidal distortion in an image projected on the screen.
[0029]
The B component light collimated by the collimating lens 202 in the B component projection system unit 200 irradiates the display panel 210. The B component light transmitted through the display panel 210 is deflected by the projection lens-side prism 220, and then combined with the G component light and the R component light by the cross prism 180 formed in the vicinity. Then, the combined light is imaged on a screen surface (not shown) by the projection lens 182.
[0030]
The G component light transmitted through the dichroic mirror 130 and separated by the dichroic mirror 132 enters the G component projection system unit 300. The R component light transmitted through the dichroic mirror 130 and the dichroic mirror 132 further enters the R component projection system unit 400 via the collimating lens 136, the mirror 138, the collimating lens 140, and the mirror 142.
[0031]
The configuration of the G component projection system unit 300 and the configuration of the R component projection system unit 400 are the same as the configuration of the B component projection system unit 200, and a description thereof will be omitted.
[0032]
FIG. 2 schematically shows a characteristic configuration of the image projection device 10 shown in FIG. In FIG. 2, the refraction of the optical axis between the light source unit 110 and the display panel 210 is omitted.
[0033]
The display panel 210 is arranged to be inclined with respect to the projection lens 182. That is, the incident surface 212 that is the main plane of the display panel 210 is inclined with respect to the main plane 183 of the projection lens 182. The incident surface 212 of the display panel 210 is also arranged perpendicular to the optical axis 510 of the B component light.
[0034]
Here, the relationship between the display panel 210 and the optical axis of light incident on the display panel 210 will be described with reference to FIG. FIG. 3 is a diagram illustrating a relationship between the display panel 210 and an optical axis 510 of light incident on the display panel 210.
[0035]
The display panel 210A is arranged with the incident surface 212A facing in a direction perpendicular to the optical axis 510. Here, let A be the area of the incident surface 212A in the display panel 210A. On the other hand, the display panel 210B is arranged so that the display panel 210A is inclined by an angle θ from a direction perpendicular to the optical axis 510. The area B of the region projected on the optical axis 510 of the incident surface 212B of the display panel 210B is:
B = Acos θ (0 ° <θ <90 °) (1)
It becomes. Here, B <A because 0 <cos θ <1. That is, when the incident surface 212 is inclined with respect to the direction perpendicular to the optical axis 510, the light beam incident on the incident surface 212 becomes thin. Also, the reflected light component of the incident light increases. Therefore, the light transmission efficiency of the display panel 210 decreases. Therefore, it is desirable to arrange the incident surface 212 so as to be perpendicular to the incident light.
[0036]
Here, the description returns to the image projection apparatus 10 according to the first embodiment. As shown in FIG. 2, in the image projection device 10 according to the first embodiment, since the incident surface 212 of the display panel 210 is provided perpendicular to the optical axis 510, the light is transmitted through the display panel 210. It is possible to prevent the transmission efficiency from being lowered.
[0037]
The projection lens side prism 220 is arranged between the display panel 210 and the projection lens 182. The projection lens side prism 220 deflects the light transmitted through the display panel 210 and guides the light to the projection lens 182 via the cross prism 180. The incident surface 222 of the projection lens-side prism 220 is arranged perpendicular to the optical axis 510.
[0038]
As described above, since the incident surface 222 of the projection lens-side prism 220 is provided perpendicular to the optical axis 510, when the light passes through the projection lens-side prism 220, the light is transmitted due to an increase in the amount of the reflection component. A decrease in efficiency can be avoided.
[0039]
Further, the apex angle 226 formed by the incident surface 222 and the deflecting surface 224 of the projection lens side prism 220 is determined based on the refractive index at the wavelength of the light passing through the projection lens side prism 220, that is, the wavelength of the B component light. At a given angle. Specifically, the angle ε is set such that the B component light incident on the incident surface 222 is refracted in a direction perpendicular to the main plane 183 of the projection lens 182.
[0040]
Therefore, the projection lens-side prism 220 can deflect the light beam transmitted through the display panel 210 in a direction perpendicular to the main plane 183 of the projection lens 182. Therefore, the projection lens 182 can project an image by efficiently using the light emitted from the light source unit 110.
[0041]
Further, since the magnitude of the apex angle 226 is determined according to the wavelength of the light passing through the projection lens-side prism 220, the light of a predetermined wavelength out of the light incident on the projection lens-side prism 220 is The light can be deflected in a direction perpendicular to the main plane 183 of the projection lens 182, and light of a color different from the color of the original image can be prevented from being incident on the projection lens 182.
[0042]
(Embodiment 2)
FIG. 4 is a diagram schematically illustrating a characteristic configuration of the image projection device 10 according to the second embodiment. In FIG. 4, the refraction of the optical axis between the light source unit 110 and the light source side prism 230 is omitted. The image projection device 10 according to the second embodiment further includes a light source side prism 230 in addition to the configuration of the image projection device 10 according to the first embodiment. In the second embodiment, the light source unit 110 emits light of a light source whose optical axis is in a direction perpendicular to the main plane 183 of the projection lens 182. That is, the optical axis 510 of the light source light emitted from the light source unit 110 is parallel to the optical axis 522 of the light deflected by the projection lens-side prism 220. This is different from the image projection device 10 according to the first embodiment.
[0043]
The light source side prism 230 is disposed adjacent to the display panel 210 and closer to the light source unit 110 than the display panel 210. The light source side prism 230 deflects light from the light source unit 110 and guides the light to the display panel 210.
[0044]
The incident surface 232 of the light source side prism 230 is provided perpendicular to the optical axis 510. The apex angle 236 formed by the incident surface 232 and the deflecting surface 234 of the light source side prism 230 is determined based on the refractive index at the wavelength of the light passing through the projection lens side prism 220, that is, the wavelength of the B component light. Since the angle ε ′ is provided, it is possible to prevent the optical axis of the transmitted light transmitted through the light source side prism 230 from being shifted from the optical axis with respect to the projection lens.
[0045]
As described above, according to the second embodiment, since the image projection device 10 includes the light source side prism 230, the light source unit 110 irradiates the light source light in a direction perpendicular to the main plane 183 of the projection lens 182. Even in this case, the light source light can be made to be incident perpendicularly to the incident surface 222 of the display panel 210 which is arranged to be inclined with respect to the main plane 183.
[0046]
Further, since the light source unit 110 can be arranged at a position where the light source light is irradiated in a direction perpendicular to the main plane 183, the light source unit 110 is disposed at a position where the light source light is irradiated obliquely to the main plane 183. The size of the main body of the image projection device 10 can be reduced as compared with the case where the unit 110 is arranged.
[0047]
Furthermore, since the light source side prism 230 deflects the optical axis 510 parallel to the optical axis 522 to the optical axis 520 in the direction perpendicular to the incident surface 212 of the display panel 210, the light transmission efficiency in the display panel 210 is reduced. Can be avoided. In addition, since the incident surface 232 is provided perpendicular to the optical axis 510, it is possible to avoid a decrease in transmission efficiency due to an increase in a reflection component or the like in the light source side prism 230.
[0048]
As described above, the characteristic configuration of the image projection device 10 according to the first and second embodiments has been described by taking the B component projection system unit 200 as an example, but the G component projection system unit 300 and the R component projection system unit 400 Has a similar configuration.
[0049]
The angle ε and the angle ε ′ of the apex angle of the prism in the G component projection system unit 300 are determined based on the wavelength of the G component light. The angle ε and the angle ε ′ of the apex angle of the prism in the R component projection system unit 400 are determined based on the wavelength of the R component light.
[0050]
Further, in Embodiment 1 and Embodiment 2, display panel 210 is arranged such that optical axis 510 and optical axis 520 penetrate the image center of display panel 210, but the position of display panel 210 is It is not limited to this. For example, the display panel 210 may shift in a direction perpendicular to the optical axis 510 and the optical axis 520.
[0051]
【The invention's effect】
As described above, according to the first aspect of the invention, the first deflecting means provided between the display panel and the projection lens converts the light beam of the light source light perpendicularly incident on the main plane of the display panel, The light can be refracted in a direction perpendicular to the plane of incidence of the projection lens. Thereby, it is possible to avoid problems such as aberration and vignetting caused by oblique incidence of transmitted light on the incident surface of the projection lens. Therefore, by arranging the display panel at an angle to the projection lens, it is possible to optically correct trapezoidal distortion and efficiently project an image on the screen without reducing the transmission efficiency of light from the light source. It works.
[0052]
According to the second aspect of the present invention, the deflecting surface of the first prism is provided so as to deflect the light beam of the light source light in a direction perpendicular to the main plane of the projection lens. Incident perpendicular to the lens. As a result, it is possible to avoid problems such as aberration and vignetting in the projection lens and decrease in luminance of an image projected on the screen. Therefore, it is possible to effectively utilize the light source light and project the original image onto the screen while eliminating the trapezoidal distortion.
[0053]
Further, according to the third aspect of the present invention, since the incident surface of the first prism is provided perpendicular to the optical axis of the light source light that has passed through the display panel, the light source light is transmitted through the first prism. Reflection can be avoided, and a reduction in transmission efficiency due to a thinner light beam incident on the first prism can be avoided. Therefore, it is possible to effectively utilize the light source light and project the original image onto the screen while eliminating the trapezoidal distortion.
[0054]
According to the invention of claim 4, the angle of the apex angle of the first prism is determined according to the wavelength of the light source light. Accordingly, it is possible to avoid a color shift in an image projected on the screen due to a shift between a light beam of transmitted light transmitted through the prism and an optical axis of the projection lens. This has the effect that the reproducibility can be kept good.
[0055]
Further, according to the invention according to claim 5, the light source light can be deflected twice by the first deflecting means and the second deflecting means. In other words, light from the light source radiated perpendicularly to the projection lens can be deflected in a direction perpendicular to the main plane of the display panel, so that trapezoidal distortion is eliminated and light from the light source is efficiently used. be able to. Furthermore, since the light source light can be irradiated in a direction perpendicular to the projection lens, by arranging the light source in an appropriate place, there is an effect that the size of the main body of the image projection apparatus can be further reduced.
[0056]
According to the sixth aspect of the present invention, the deflecting surface of the second prism is provided so as to deflect the light beam of the light source light in a direction perpendicular to the main plane of the display panel. Incident perpendicular to the panel. Thus, it is possible to prevent the light source light from being reflected on the display panel or the light flux incident on the display panel from becoming thinner, thereby preventing the transmission efficiency from being reduced. Therefore, it is possible to effectively utilize the light source light and project the original image onto the screen while eliminating the trapezoidal distortion.
[0057]
According to the seventh aspect of the present invention, since the incident surface of the second prism is provided perpendicular to the optical axis of the light of the light source, it is possible to prevent the light source light from being reflected by the second prism. In addition, it is possible to avoid a decrease in transmission efficiency due to a thin light beam incident on the second prism. Therefore, it is possible to effectively utilize the light source light and project the original image onto the screen while eliminating the trapezoidal distortion.
[0058]
Further, according to the invention of claim 8, the angle of the apex angle of the second prism is determined according to the wavelength of the light source light. Accordingly, it is possible to avoid a color shift in an image projected on the screen due to a shift between the light beam of the transmitted light transmitted through the second prism and the optical axis of the projection lens. This has the effect of maintaining good color reproducibility of the image.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of an image projection device according to a first embodiment;
FIG. 2 is a diagram schematically showing a configuration characteristic of the image projection apparatus shown in FIG.
FIG. 3 is a diagram illustrating a relationship between a display panel and incident light.
FIG. 4 is a diagram schematically illustrating a characteristic configuration of the image projection apparatus according to the second embodiment;
[Explanation of symbols]
Reference Signs List 10 Image projection device 110 Light source unit 112 Ultra-high pressure mercury lamp 114 Elliptical curved surface reflector 120 Multi-lens 122 Deflector 124 Condenser lens 130, 132 Diclock mirror 180 Cross prism 182 Projection lens 200 B component projection system unit 202 Collimating lens 210 Display panel 220 Projection lens side prism 230 Light source side prism 300 G component projection system unit 400 R component projection system unit 510, 512, 520, 522 Optical axis

Claims (8)

An image projection device that irradiates light from a light source and projects an image displayed on a display panel onto a screen,
A projection lens arranged to be inclined with respect to a main plane of the display panel, and projecting an image displayed on the display panel onto the screen;
An image projection apparatus, comprising: a first deflecting unit provided between the display panel and the projection lens, for deflecting a light beam of the light source light in a direction perpendicular to a main plane of the projection lens. 2. The image projection apparatus according to claim 1, wherein the first deflecting unit is a first prism having a deflecting surface that deflects the light beam of the light source light in a direction perpendicular to a main plane of the projection lens. apparatus. The said 1st deflection | deviation means is the 1st prism which has the incident surface provided perpendicularly with respect to the optical axis of the said light source light which passed the said display panel, The Claim 1 or 2 characterized by the above-mentioned. Image projection device. 4. The image projection device according to claim 2, wherein the first prism has a vertex angle determined according to a wavelength of the light source light. 5. A second deflecting unit that is provided between the light source and the display panel and deflects a light beam of the light source light perpendicular to the projection lens in a direction perpendicular to a main plane of the display panel. The image projection device according to any one of claims 1 to 4, wherein 6. The image projection according to claim 5, wherein the second deflecting unit is a second prism having a deflecting surface that deflects the light beam of the light source light in a direction perpendicular to a main plane of the display panel. apparatus. The image projection apparatus according to claim 5, wherein the second deflecting unit includes a second prism having an incident surface provided perpendicular to an optical axis of the light source light. The image projection apparatus according to claim 6, wherein the second prism has a vertex angle determined according to a wavelength of the light source light.

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