JP2018081325A - Projection type display unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display unit that can suppress a reduction in contrast of a projection image.SOLUTION: A projection type display unit (1) of the present invention comprises: an illumination part (25) that emits a plurality of colors of light having a predetermined polarization direction; a plurality of light path adjustment parts (40R, 40G, and 40B) that totally reflect the respective plurality of colors of light; a plurality of light modulation parts (50R, 50G, and 50B) that modulate the respective plurality of colors of light totally reflected by the plurality of light path adjustment parts, and emit the respective plurality of colors of modulated light; a composing part (60) that reflects or transmits the plurality of colors of modulated light emitted from the light modulation parts to be emitted in the same direction; and correction parts (70R, 70G, and 70B) that are provided on light paths between the illumination part and composing part, and change the polarization states of the rays of incident light to convert the rays of light made incident on the composing part into rays of linearly polarized light.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a projection display device.

  In recent years, display devices using a plurality of display elements such as DMD (Digital Micromirror Device) have been proposed. A display device using a plurality of display elements has a light combining optical system that combines a plurality of projection lights emitted from the display elements on the same optical axis, and projects the combined projection light. For example, Patent Document 1 discloses a display device having three DMDs as display elements and a cross dichroic prism (hereinafter referred to as XDP) as a light combining optical system.

  FIG. 1 is a diagram for explaining a configuration of a display device described in Patent Document 1. A display device 1000 shown in FIG. 1 includes an illumination optical system 100, a light separation XDP 210, a dichroic mirror 220, reflection mirrors 230 and 240, condenser lenses 250 and 260, three DMDs 300R, 300G, and 300B, Two TIR (Total Internal Reflection) prisms 400R, 400G, and 400B, an XDP 500 for photosynthesis, and a projection lens 600 are provided.

  The light emitted from the illumination optical system 100 is separated into red light and mixed light of green and blue in the light separation XDP 210. The red light enters the TIR prism 400R via the reflection mirror 240 and the condenser lens 260. The mixed light of green and blue is incident on the dichroic mirror 220 via the reflection mirror 230 and the condenser lens 250. In the dichroic mirror 220, the mixed light of green and blue is separated into green light and blue light, the green light is incident on the TIR prism 400G, and the blue light is incident on the TIR prism 400B.

  The light incident on each of the TIR prisms 400R, 400G, and 400B is totally reflected by each of the first surfaces 402R, 402G, and 402B, and DMDs 300R, 300G, and 400D provided corresponding to the TIR prisms 400R, 400G, and 400B, respectively. Incident on each of 300B.

  The DMDs 300R, 300G, and 300B have a plurality of micromirrors arranged in a matrix in the image forming area, and rotate each micromirror to change the light reflection direction, thereby modulating incident light. Output as image light. The image lights emitted from the DMDs 300R, 300G, and 300B are transmitted through the corresponding TIR prisms 400R, 400G, and 400B and enter the XDP 500.

  The XDP 500 has second surfaces 506 and 508 that transmit or reflect the incident image light of each color. The XDP 500 emits a plurality of image lights incident on the second surfaces 506 and 508 in the same direction, and outputs each color light. Synthesize image light. The combined image light is emitted from the XDP 500 toward the projection lens 600 and projected onto a screen (not shown) via the projection lens 600.

  Since the XDP 500 reflects one of the s-polarized light and the p-polarized light and transmits the other on the second surfaces 506 and 508, the second surface 506 and 508 can combine the light from each of the DMDs 300 R, 300 G, and 300 B efficiently. The incident light on the surfaces 506 and 508 is s-polarized or p-polarized.

  The long sides of the image forming regions of the DMDs 300R, 300G, and 300B are installed so as to be inclined by 45 ° with respect to the side of the light incident surface of the XDP 500. Therefore, in order to display the projected image normally, it is necessary to tilt the display device 1000 by 45 ° from the horizontal direction.

JP 2000-330072 A

  In the display device 1000 described in Patent Document 1, troublesome operations such as tilting the housing must be performed only when an image is projected.

  On the other hand, if the DMD 300R, 300G, 300B image forming area is set so that the long side is parallel to the side of the light incident surface of the XDP 500, the projected image can be displayed in a normal state without tilting the housing. Can be displayed.

  However, in this case, it is necessary to make light incident on each of the TIR prisms 400R, 400G, and 400B from an angle of 45 ° with respect to the incident surface of the XDP 500, and as a result, the first surface of the TIR prisms 400R, 400G, and 400B. When light is totally reflected by 402R, 402G, and 402B, it becomes elliptically polarized light. In this case, the light incident on the XDP 500 cannot be s-polarized light or p-polarized light, and there is a problem that the contrast and brightness of the projected image are lowered.

  The objective of this invention is providing the display apparatus which can suppress the fall of the contrast of a projection image.

The projection display device according to the present invention is
An illumination unit that emits a plurality of colored lights having a predetermined polarization direction;
A plurality of optical path adjustment units that totally reflect the plurality of colored lights, respectively;
A plurality of light modulation units that respectively modulate a plurality of color lights totally reflected by the plurality of optical path adjustment units and emit a plurality of color modulation lights, respectively;
A plurality of color-modulated light beams emitted from each light modulation unit in the same direction;
A correction unit which is provided on an optical path between the illumination unit and the combining unit and changes the polarization state of the incident light so that the light incident on the combining unit is linearly polarized light. The correction unit includes at least one 1/8 wavelength plate or 5/8 wavelength plate.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the display apparatus which can suppress the fall of the contrast of a projection image.

It is a figure for demonstrating the structure of the display apparatus 1000 concerning the comparative example of this invention. It is a figure for demonstrating arrangement | positioning of each component in the modification of the display apparatus of FIG. In the modification of FIG. 2, it is a figure for demonstrating the relationship between the polarization direction used as s polarized light and p polarized light with respect to a 1st surface, and the polarization direction of the incident light to a 1st surface. It is a figure for demonstrating the structure of the display apparatus 1 concerning the 1st Embodiment of this invention. It is a figure for demonstrating the structure of TIR prism 40B. It is a figure for demonstrating the detailed structure of a part of TIR prism 40B. It is a figure for demonstrating the structure of DMD50B. It is a figure for demonstrating operation | movement of the micromirror 51. FIG. It is a figure for demonstrating the relative arrangement | positioning of TIR prism 40B, DMD50B, and XDP60. It is a figure for demonstrating the relative arrangement | positioning of TIR prism 40B, DMD50B, and XDP60. It is a figure for demonstrating the relationship between the polarization direction of the light which injects into TIR prism 40B, and the polarization direction used as the s-polarization or p-polarization with respect to the 1st surface 43B of TIR prism 40B. It is a figure for demonstrating the polarization state of the light which injects into TIR prism 40B, and the image light which DMD50B radiate | emits. It is a figure for demonstrating the structure of the display apparatus 2 concerning the 2nd Embodiment of this invention. It is a figure for demonstrating the polarization state of the light which injects into the TIR prism 40B of the display apparatus 2, and the image light which DMD50B radiate | emits. It is a figure for demonstrating the structure of the display apparatus 3 concerning the 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in this specification and drawing, the description which overlaps may be abbreviate | omitted by attaching | subjecting the same code | symbol about the component which has the same function. For the sake of simplicity, the light beam is shown as a straight line in the drawing.

  First, the mechanism by which the light reflected by the TIR prism becomes elliptically polarized light will be described.

  FIG. 2 is a diagram for explaining the arrangement of DMD 300B, TIR prism 400B, and XDP 500. FIG.

  DMD 300 </ b> B is installed in parallel to the incident surface of XDP 500. That is, the rectangular image forming area of DMD 300B and the incident surface of XDP 500 are both parallel to the yz plane. The TIR prism 400B is installed between the DMD 300B and the XDP 500. A TIR prism 400B is installed so that incident light enters the DMD 300B from a direction substantially perpendicular to the rotation axis 302 of the micromirror 301 provided in the rectangular image forming area of the DMD 300B. That is, incident light is totally reflected by the first surface 402B, which is the total reflection surface of the TIR prism 400B, and then exits from the TIR prism 400B and enters the DMD 300B. The TIR prism 400B is arranged so that the first surface 402B gradually approaches the rectangular image forming area of the DMD 300B. More specifically, the first surface 402B is a slope with respect to the rectangular image forming area of the DMD 300B, and is a slope along a direction substantially perpendicular to the rotation axis 302 of the micromirror 301.

  FIG. 3 is a diagram for explaining the relationship with the polarization direction of incident light on the first surface 402B of the TIR prism 400B in the arrangement shown in FIG. When light is incident on the TIR prism 400B from an angle of 45 ° with respect to the incident surface of the XDP 500, the incident surface when the light is incident on the TIR prism 400B makes an angle of 45 ° with respect to the incident surface of the XDP 500. It becomes a surface. Therefore, the direction parallel or perpendicular to the incident surface of the TIR prism 400B does not coincide with the direction parallel or perpendicular to the incident surface of the XDP 500, and s-polarized light or p with respect to the second surface 506 of the XDP 500. The polarized light does not become s-polarized light or p-polarized light with respect to the first surface 402B of the TIR prism 400B. The incident light to the TIR prism 400B has a polarization direction that is s-polarized light or p-polarized light with respect to the second surface 506 of the XDP 500. Therefore, when incident on the first surface 402B of the TIR prism 400B, the s-polarized light is incident. The light includes a component and a p-polarized component.

  When light including the s-polarized component and the p-polarized component is totally reflected, the polarization state of the light is disturbed. Specifically, when the light is totally reflected, a part of the energy of the light incident on the total reflection surface oozes slightly in the medium forming the total reflection surface, and evanescent light is generated. Since the energy of evanescent light propagates in a direction parallel to the total reflection surface, a phenomenon called the Goose Henschen shift in which the phase of the light changes occurs. Since the amount of phase change due to the Goose Henschen shift differs between the s-polarized component and the p-polarized component, when linearly polarized light including the s-polarized component and p-polarized component is totally reflected, the linearly polarized light changes to elliptically polarized light.

  Here, the arrangement of DMD 300B, TIR prism 400B, and XDP 500 and the polarization direction when blue light enters XDP 500 through TIR prism 400B, DMD 300B have been described, but the same applies to red light and green light. .

(First embodiment)
FIG. 4 is a diagram for explaining the configuration of the display device 1 according to the first embodiment of the present invention. The display device 1 includes a light source 10, an illumination optical system 20, a light separation optical system 30, TIR prisms 40R, 40G, and 40B, DMDs 50R, 50G, and 50B, an XDP 60, and correction optical elements 70R, 70G, and 70B. And a projection optical system 80. The projection optical system 80 is a projection unit that projects light synthesized by the XDP 60. The projection optical system 80 enlarges the incident light and projects it onto a screen (not shown).

  The light source 10 includes a light source lamp 11 and a reflector 12. The light source lamp 11 is, for example, a metal halide lamp or a high-pressure mercury lamp, and the type thereof is not particularly limited. The reflector 12 converts the light emitted from the light source lamp 11 into substantially parallel light and emits it. The substantially parallel light emitted from the light source 10 enters the illumination optical system 20.

  The illumination optical system 20 includes a first lens array 21, a second lens array 22, a polarization conversion element 23, and a superimposing lens 24. The illumination optical system 20 generates linearly polarized light from substantially parallel light emitted from the light source 10.

  The first lens array 21 and the second lens array 22 are composed of a large number of lenses arranged in a matrix. The first lens array 21 is configured to divide incident light into the same number of light beams as the constituent lenses, and to image each of the divided light beams in the vicinity of the second lens array 22.

  The light emitted from the second lens array 22 enters the polarization conversion element 23, and is converted into linearly polarized light having a predetermined polarization direction by the polarization conversion element 23.

  The linearly polarized light emitted from the polarization conversion element 23 enters the superimposing lens 24. The light beams divided by the first lens array 21 are superimposed on the DMDs 50R, 50G, and 50B by the superimposing lens 24.

  The light separation optical system 30 separates the light from the illumination optical system 20 into a plurality of lights having different colors. For example, the light separation optical system 30 reflects the first dichroic mirror 31 that reflects blue light and transmits light having a longer wavelength than blue light, and reflects light that has longer wavelength than green by reflecting green light. And a second dichroic mirror 32 that transmits the light. The light separation optical system 30 may further include a reflection mirror that changes the optical path.

  Light emitted from the illumination optical system 20 is reflected by blue light from the first dichroic mirror 31, and light having a longer wavelength is transmitted and incident on the second dichroic mirror 32. Of the light incident on the second dichroic mirror 32, green light is reflected by the second dichroic mirror 32, and light having a longer wavelength (for example, red light) is transmitted through the second dichroic mirror 32. To do.

  The blue light reflected by the first dichroic mirror 31 enters the TIR prism 40B. The green light reflected by the second dichroic mirror 32 is reflected by the reflection mirror 36 and then enters the TIR prism 40G. The red light transmitted through the second dichroic mirror 32 is reflected by the reflection mirrors 33, 34, and 35 and then enters the TIR prism 40R.

  The light source 10, the illumination optical system 20, and the light separation optical system 30 are collectively referred to as an illumination unit 25. The illumination unit 25 emits a plurality of color lights having a predetermined polarization direction.

  The TIR prisms 40R, 40G, and 40B are optical path adjustment units that change the optical path of incident light. Specifically, the TIR prisms 40R, 40G, and 40B totally reflect each color light from the illumination unit 25 and emit the light toward the DMDs 50R, 50G, and 50B. The color lights modulated by the micromirrors of DMDs 50R, 50G, and 50B are transmitted through TIR prisms 40R, 40G, and 40B, and enter XDP 60.

  FIG. 5 is a diagram for explaining the configuration of the TIR prism 40B. FIG. 5 shows the TIR prism 40B and the DMD 50B, but the same applies to the TIR prisms 40R and 40G and the DMDs 50R and 50G.

  A TIR prism 40B shown in FIG. 5 includes a prism 41B and a prism 42B, and a first surface 43B is formed between the prism 41B and the prism 42B by an air gap. Since the first surface 43B has an interface having a different refractive index due to an air gap, when light is incident on the first surface 43B at an angle greater than the critical angle, the light is totally reflected. In the TIR prism 40B, the angle at which the light from the illumination unit 25 is incident on the first surface 43B is equal to or greater than the critical angle, and the totally reflected light enters the DMD 50B and is modulated by each micromirror of the DMD 50B. The light reflected by each micromirror is arranged to enter the first surface 43B at an angle less than the critical angle. That is, the TIR prism 40B totally reflects the light from the illumination unit 25 and emits it toward the DMD 50B, and transmits the light from the DMD 50B and emits it toward the XDP 60.

  FIG. 6 is a diagram for explaining a detailed configuration of the prism 41B. 6 shows the prism 41B, the same applies to the prisms 41R and 41G included in the TIR prisms 40R and 40G. The internal angles of the triangles on the bottom surface of the prism 41B are 33 °, 50 °, and 97 °, respectively, the refractive index of glass is 1.517, and the angle at which light is incident on the first surface 43B is 48.5 °. At this time, the angle at which the light exits from the prism 41B and enters the DMD 50B is 24 °.

  Returning to the description of FIG.

  DMDs 50R, 50G, and 50B are provided corresponding to the TIR prisms 40R, 40G, and 40B, respectively, and modulate the light totally reflected by the first surfaces 43R, 43G, and 43B of the corresponding TIR prisms 40R, 40G, and 40B, respectively. And is also referred to as a light modulator.

  FIG. 7 is a diagram for explaining the configuration of the DMD 50B. 7 shows the DMD 50B, the same applies to the DMDs 50R and 50G. The DMD 50B has a plurality of micromirrors 51 arranged in a matrix, and each micromirror 51 corresponds to one pixel of a projected image. Each micromirror 51 rotates around the rotation axis 52, whereby the angle with respect to incident light changes. The micro mirror 51 of the DMD 50 </ b> B has a rotation axis 52 facing the diagonal direction of the square micro mirror 51, and the rotation axis 52 is arranged so that the plane including incident light and reflected light is orthogonal to the rotation axis 52. ing.

  FIG. 8 is a diagram for explaining the operation of the micromirror 51. A control unit (not shown) drives each micromirror 51 in accordance with the video signal, and switches to an ON state tilted in the direction in which light is incident or an OFF state tilted in the direction opposite to the direction in which light is incident. Assuming that the rotation angle when the reflecting surfaces of the plurality of micromirrors 51 form one plane is 0 °, each micromirror 51 is inclined ± 12 ° around the rotation axis 52. In this case, when the light having an incident angle of 24 ° is reflected by the micromirror 51 in the ON state, the light travels in the normal direction of the micromirror 51 when the rotation angle is 0 °. Further, when the light having an incident angle of 24 ° is reflected by the micromirror 51 in the OFF state, the light proceeds in a direction that forms an angle of 48 ° with the normal line of the micromirror 51 when the rotation angle is 0 °.

  The ON light reflected by the DMDs 50R, 50G, and 50B passes through the first surfaces 43R, 43G, and 43B of the TIR prisms 40R, 40G, and 40B, is synthesized by the XDP 60, and is combined into a screen (not shown) by the projection lens. Projected. Moreover, OFF light is absorbed by the light absorber installed between DMD 50R, 50G, 50B and XDP 60, and does not reach the screen. By changing the ratio between the time when each micromirror 51 is in the ON state and the time when it is in the OFF state, the brightness of the pixel corresponding to each micromirror 51 is changed.

  In FIG. 4, an XDP 60 is a combining unit that combines light by reflecting or transmitting each light emitted from the DMDs 50R, 50G, and 50B on the second surfaces 61 and 62 in the same direction.

  Specifically, the second surfaces 61 and 62 transmit p-polarized green light, the second surface 61 reflects s-polarized red light, and the second surface 62 reflects s-polarized light. Reflects blue light. However, even if the illumination unit 25 emits linearly polarized light that is s-polarized light or p-polarized light with respect to the second surfaces 61 and 62, the polarization state is disturbed when reflected by the first surface of the TIR prism 40. It becomes elliptically polarized light.

9 and 10 are diagrams for explaining the relative arrangement of the TIR prism 40B, DMD 50B, and XDP 60. FIG. The DMD 50B and the TIR prism 40B are arranged so that the rotation axis 52 provided in the diagonal direction of each micromirror 51 provided in the image forming area of the DMD 50B and the plane including the incident light and the reflected light are orthogonal to each other. Deploy. Further, the DMD 50B is arranged with respect to the XDP 60 so that the long side of the image forming area of the DMD 50B is parallel to the side of the upper surface of the XDP 60.
Light is incident on the TIR prism 40B from an angle of 45 ° with respect to the incident surface of the XDP 60. As a result, the light totally reflected by the first surface 43B of the TIR prism 40B enters the DMD 50 from an angle of 45 ° with respect to the incident surface of the XDP 60.

  FIG. 11 is a diagram for explaining the relationship between the polarization direction of the light incident on the TIR prism 40B and the polarization direction of s-polarized light or p-polarized light with respect to the first surface 43B of the TIR prism 40B. In the example of FIG. 11, the incident light on the TIR prism 40 </ b> B has a polarization direction that is p-polarized with respect to the second surfaces 61 and 62 of the XDP 60. However, since the direction of the inclined surface of the first surface 43B and the polarization direction of the incident light are neither coincident nor orthogonal, the incident light to the TIR prism 40B has an s-polarized component and This results in light containing a p-polarized component.

  FIG. 12 is a diagram showing the polarization state of the light incident on the TIR prism 40B and the image light emitted from the DMD 50B. The incident light to the TIR prism 40B is linearly polarized light that is polarized in a direction parallel or perpendicular to the incident surface of the XDP 60, and is light that includes an s-polarized component and a p-polarized component with respect to the first surface 43B. ing. In this case, when the light is totally reflected by the first surface 43B, a phase change of light called a Goose Henschen shift occurs. The amount of this phase change differs between the s-polarized component and the p-polarized component. For example, in the case of the TIR prism 40B having the configuration described with reference to FIGS. 5 and 6, the phase change occurring on the first surface 43B of the TIR prism 40B is 56.4 ° for s-polarized light and 102.0 for p-polarized light. °. For this reason, after the light is totally reflected, the relative phase difference generated between the s-polarized light and the p-polarized light is 45.6 °. This relative phase difference corresponds to about one-eighth wavelength.

  As described above, when the direction of inclination of the total reflection surface and the polarization direction of the linearly polarized light are not coincident or orthogonal, the linearly polarized light reflected by the total reflection surface becomes elliptically polarized light. For this reason, light incident on the DMD 50B from the TIR prism 40B becomes elliptically polarized light. Further, since the polarization state of the light does not change when the light is reflected by the DMD 50B, the light modulated by the DMD 50B becomes elliptically polarized light.

  9-12, the arrangement of TIR prisms 40B, DMD 50B, and XDP 60 through which blue light passes and the polarization state of blue light have been described, but the same applies to red light and green light.

  The correction optical elements 70R, 70G, and 70B shown in FIG. 4 are provided on the optical path between the illumination unit 25 and the XDP 60, change the polarization state of the incident light, and change the incident light to the XDP 60 to s-polarized light or p-polarized light. This is a correction unit for polarization. Each of the correction optical elements 70R, 70G, and 70B is disposed on the optical path between each of the TIR prisms 40R, 40G, and 40B and the XDP 60. Each of the correction optical elements 70R, 70G, and 70B corrects the light modulated by the DMDs 50R, 50G, and 50B and transmitted through the TIR prisms 40R, 40G, and 40B to form linearly polarized light. The XDP 60 is designed to synthesize light of a polarization component in a specific direction on the same optical axis with the image light emitted from the DMDs 50R, 50G, and 50B. Accordingly, the correction optical elements 70R, 70G, and 70B correct the light incident on the XDP 60 so that the light is polarized in this specific direction. More specifically, the correction optical elements 70R, 70G, and 70B are provided for each color light emitted from the illumination unit 25, and the green correction optical element 70G provided corresponding to the green light is incident. The elliptically polarized light is converted into p-polarized light, and the red correcting optical element 70R and the blue correcting optical element 70B convert the incident elliptically polarized light into s-polarized light.

  The light incident on the correction optical elements 70R, 70G, and 70B is totally reflected by the first surfaces 43R, 43G, and 43B of the TIR prisms 40R, 40G, and 40B, and changes from linearly polarized light to elliptically polarized light. The correction optical elements 70R, 70G, and 70B are incident so that, for example, the relative phase difference between the s-polarized component and the p-polarized component of light generated when the light is totally reflected by the TIR prisms 40R, 40G, and 40B is canceled out. The phase of the s-polarized component and the p-polarized component of the emitted light is changed. 4 to 12, the correction optical elements 70R, 70G, and 70B have at least one eighth-wave plate (1 / 8λ plate). For example, the correction optical elements 70R, 70G, and 70B include 1/8 wavelength plate or 5/8 wavelength plate (5 / 8λ plate). The correction optical element 70G for green corresponding to the light transmitted through the second surfaces 61 and 62 of the XDP 60 is a 5/8 wavelength plate. The red correction optical element 70R and the blue correction optical element 70B corresponding to the light reflected by the second surfaces 61 and 62 of the XDP 60 are 1/8 wavelength plates. As a result, red image light is corrected from elliptically polarized light to light polarized in a direction perpendicular to the incident surface of XDP 60, and green image light is polarized in a direction parallel to the incident surface of XDP 60 from elliptically polarized light. The blue image light is corrected to light polarized in the direction perpendicular to the incident surface of the XDP 60 from the elliptically polarized light. Therefore, when the light enters the second surface 61 or 62 of the XDP 60, the red and blue image light becomes s-polarized light, and the green image light becomes p-polarized light.

  Here, as the correction optical element 70G for green, a half-wave plate (1 / 2λ plate) and an eighth-wave plate (1 / 8λ plate) are used instead of the five-eight wavelength plate. They may be used side by side along the traveling direction. In the correction optical elements 70R, 70G, and 70B, the light transmitted through the second surfaces 61 and 62 of the XDP 60 becomes p-polarized light, the light reflected by the second surface 61 and the light reflected by the second surface 62 are s-polarized light. Any configuration can be used.

(Modification)
In the above embodiment, the correction optical elements 70R, 70G, and 70B cancel the relative phase difference between the s-polarized component and the p-polarized component of light that occurs when the light is totally reflected by the TIR prisms 40R, 40G, and 40B. As described above, the phase of the s-polarized component and the p-polarized component of the incident light is changed. However, the present invention is not limited to such an example. For example, the correction optical elements 70 </ b> R, 70 </ b> G, and 70 </ b> B may change the polarization state of the incident light so as to remove light having a polarization component other than a specific direction that is incident on the XDP 60.

  Specifically, the correction optical elements 70R, 70G, and 70B include at least one polarizing plate. For example, the correction optical element 70R for red and the correction optical element 70B for blue corresponding to the light reflected by the second surface 61 or 62 of the XDP 60 can be polarizing plates. At this time, the correction optical element 70G for green corresponding to the light transmitted through the second surfaces 61 and 62 of the XDP 60 has a polarizing plate and a half-wave plate arranged in this order along the light traveling direction. May be used. The polarizing plate transmits only light having a specific polarization direction and absorbs or reflects light having the other polarization direction. All of the polarizing plates used in the correction optical elements 70R, 70G, and 70B have a characteristic of transmitting polarized light in a direction perpendicular to the incident surface of the XDP 60. Thereby, the light transmitted through the polarizing plate becomes s-polarized light, and further, the green light becomes p-polarized light by passing through the half-wave plate.

  As described above, according to the first embodiment of the present invention, a plurality of color lights having a predetermined polarization direction emitted from the illumination unit 25 are incident on each of the plurality of TIR prisms 40R, 40G, and 40B. And totally reflected. The totally reflected light is modulated by DMDs 50R, 50G, and 50B provided corresponding to TIR prisms 40R, 40G, and 40B, respectively. The respective lights emitted from the DMDs 50R, 50G, and 50B are synthesized by the XDP 60 and emitted. On the optical path between the illumination unit 25 and the XDP 60, correction optical elements 70R, 70G, and 70B that change the polarization state so that the light incident on the XDP 60 is s-polarized light or p-polarized light are provided. As a result, even if the light becomes elliptically polarized before the light enters the XDP 60, the light incident on the XDP 60 can be s-polarized light or p-polarized light, so that stray light is generated inside the XDP 60. It is possible to suppress the reduction of the contrast of the projected image.

  Further, according to the present embodiment, the correction optical elements 70R, 70G, and 70B have the phase difference between the s-polarized component and the p-polarized component of the light that occurs when the light is totally reflected by the TIR prisms 40R, 40G, and 40B. Change the polarization state of the light so that it is canceled out. As a result, even when a phase difference occurs between the s-polarized component and the p-polarized component when the light is totally reflected by the TIR prisms 40R, 40G, and 40B, the phase difference is canceled out and more reliably. Therefore, it is possible to suppress a decrease in the contrast of the projected image. Further, by canceling the phase difference, the light that has become stray light can also be used as the projection light, so that the brightness of the projected image can be improved.

  Further, according to the present embodiment, the correction optical elements 70R, 70G, and 70B have at least one eighth-wave plate. More specifically, the XDP 60 reflects or transmits each color modulation light in the same direction. At this time, the correction optical elements 70R, 70G, and 70B are provided corresponding to each light incident on the XDP 60, and the correction optical elements 70R and 70B corresponding to the light reflected by the XDP 60 are 1/8 wavelength plates. The correction optical element 70G corresponding to the light transmitted through the XDP 60 has at least one half-wave plate. As a result, when a phase difference of 1/8 wavelength occurs on the reflecting surfaces 43R, 43G, and 43B of the TIR prisms 40R, 40G, and 40B, it is possible to more reliably suppress the reduction in the contrast of the projected image. Thus, the brightness of the projected image can be improved.

  Further, according to the present embodiment, the correction optical elements 70R, 70G, and 70B are provided on the optical paths between the TIR prisms 40R, 40G, and 40B and the XDP 60, respectively. As a result, linearly polarized light whose light polarization state has been converted immediately before entering the XDP 60 becomes linearly polarized light, so that the light incident on the XDP 60 can be converted into linearly polarized light and the contrast of the projected image can be reduced. It becomes possible to suppress.

  Further, according to the modification of the present embodiment, the correction optical elements 70R, 70G, and 70B include at least one polarizing plate. More specifically, the XDP 60 reflects or transmits each color modulation light in the same direction. At this time, the correction optical elements 70R, 70G, and 70B are provided corresponding to each light incident on the XDP 60, and the correction optical elements 70R and 70B corresponding to the light reflected by the XDP 60 are polarizing plates and are transmitted through the XDP 60. The correction optical element 70G corresponding to light has a polarizing plate and a half-wave plate. Thereby, components other than s-polarized light or p-polarized light polarized in a direction perpendicular or parallel to the incident surface of the XDP 60 out of the light incident on the XDP 60 are reflected or absorbed. Therefore, it is possible to more reliably reduce the light that becomes stray light in the XDP 60 and suppress the decrease in the contrast of the projected image.

(Second Embodiment)
FIG. 13 is a diagram for explaining the configuration of the display device 2 according to the second embodiment of the present invention.

  The display device 1 includes correction optical elements 70R, 70G, and 70B that convert light into linearly polarized light after the polarization state is disturbed by the TIR prisms 40R, 40G, and 40B. The correction optical elements 70R, 70G, and 70B include: It is provided between each TIR prism 40R, 40G, 40B and the XDP 60. On the other hand, the display device 2 corrects the light to be elliptically polarized before entering the TIR prisms 40R, 40G, and 40B so that the light totally reflected by the TIR prisms 40R, 40G, and 40B becomes linearly polarized light. Optical elements 90R, 90G, and 90B are provided instead of the correction optical elements 70R, 70G, and 70B.

  Hereinafter, differences from the display device 1 will be mainly described.

  The display device 2 includes correction optics provided on the optical path between the illumination unit 25 and the TIR prisms 40R, 40G, and 40B, for example, on the optical path between the light separation optical system 30 and the TIR prisms 40R, 40G, and 40B. An element 90 is included. More specifically, the display device 2 includes the red correction optical element 90R disposed between the reflection mirror 35 and the red TIR prism 40R, the second dichroic mirror 32, and the green TIR prism 40G. The correction optical element 90G for green disposed between the two. In addition, the display device 2 includes a blue correction optical element 90B disposed between the first dichroic mirror 31 and the blue TIR prism 40B.

  Each of the correction optical elements 90R, 90G, and 90B changes the polarization state of the incident light so that the light incident on the XDP 60 becomes linearly polarized light having a predetermined polarization direction. Specifically, the correction optical elements 90R, 9G, and 90B allow the light before being incident on the TIR prisms 40R, 40G, and 40B so that the relative phase difference generated between the p-polarized light and the s-polarized light is canceled by the total reflection surface. The polarization state is corrected in advance.

  As described in the first embodiment, in the configuration described with reference to FIGS. 5 to 12, a relative phase difference of about one-eighth wavelength is generated between the p-polarized light and the s-polarized light. The correction optical elements 90R, 90G, and 90B give a phase difference that is opposite in sign and equal in magnitude to the linear phase illumination light before entering the TIR prisms 40R, 40G, and 40B. Convert linearly polarized light into elliptically polarized light. For example, the correction optical element 90R for red and the correction optical element 90B for blue are 1/8 wavelength plates, and the correction optical element 90G for green is a 5/8 wavelength plate.

  FIG. 14 is a diagram for explaining polarization states of the color light incident on the TIR prism 40B of the display device 2 and the color light on the total reflection surface of the TIR prism 40B. The color light that passes through the correction optical element 90B of the display device 2 and enters the TIR prism 40B is converted into elliptically polarized light. When this elliptically polarized light is totally reflected by the total reflection surface of the TIR prism 40B, a Goose Henschen shift occurs, and a phase change occurs accordingly. Although the amount of phase change differs between s-polarized light and p-polarized light, the amount of phase change caused by transmission through the correction optical element 90 and the amount of phase change caused by the Goose Henschen shift can be combined. The amount of change and the amount of change of p-polarized light are approximately equal, and the relative phase difference is reduced.

  As a result, the light incident on the DMD 50B becomes linearly polarized light polarized in a direction parallel to the incident surface of the XDP 60, and the polarization state does not change when reflected by the DMD 50B. The linearly polarized light is polarized in a direction parallel to the incident surface.

  In FIG. 14, the change in the polarization state until the blue light enters the XDP 60 via the TIR prism 40B and the DMD 50B has been described, but the same applies to the red light and the green light.

(Modification)
In the second embodiment, the correction optical elements 90R, 90G, and 90B are arranged between the light separation optical system 30 and the TIR prisms 40R, 40G, and 40B, and enter the TIR prisms 40R, 40G, and 40B. Although the polarization state of the illumination light immediately before is corrected, the present invention is not limited to such an example. The arrangement and number of the correction optical elements 90R, 90G, and 90B included in the display device 2 may be any configuration that increases the light incident on the projection optical system 80.

  For example, instead of the correction optical elements 90R, 90G, and 90B, one correction optical element may be disposed between the illumination optical system 20 and the light separation optical system 30. In this case, it is necessary to pay attention to the number of reflecting surfaces because the direction of polarization rotation changes on each reflecting surface. Further, instead of the correction optical elements 90R, 90G, and 90B, two correction optical elements are provided between the first dichroic mirror 31 and the blue TIR prism 40B, and between the first dichroic mirror 31 and the second dichroic mirror 31B. Each may be arranged between the dichroic mirror 32 and the dichroic mirror 32.

  Further, as the correction optical element 70G for green, a half-wave plate and an eighth-wave plate may be used side by side along the light traveling direction instead of the fifth-eight wavelength plate.

  As described above, according to the second embodiment of the present invention, the correction optical elements 90R, 90G, 90B are provided on the optical path between the illumination unit 25 and the TIR prisms 40R, 40G, 40B. Even in this case, it is possible to suppress a decrease in the contrast of the projected image. In addition, the number of correction optical elements and the degree of freedom of arrangement can be increased as compared with the case of correcting the polarization state of light emitted from the TIR prisms 40R, 40G, and 40B. In addition, the number and arrangement of correction optical elements can be designed flexibly.

(Third embodiment)
FIG. 15 is a diagram for explaining the configuration of the display device 3 according to the third embodiment of the present invention.

  The illumination unit 25 of the display device 1 and the display device 2 is used as illumination light that illuminates the DMD 50 by separating white light into a plurality of color lights, whereas the illumination unit 26 of the display device 3 includes each of a plurality of light sources. Is used as illumination light.

  The illumination unit 26 includes light sources 10R, 10G, and 10B that emit red, green, and blue color lights, respectively, and a conversion optical system that converts red, green, and blue color lights to color illumination lights having a predetermined polarization direction, respectively. It has illumination optical systems 20R, 20G, and 20B.

  Each light source 10 includes a light emitting element 13 that emits color light of each color, and a lens 14 that converts the color light emitted from the light emitting element 13 into substantially parallel light. For example, the light source 10R includes a light emitting element 13R that emits red color light, and a lens 14R that converts the color light emitted from the light emitting element 13R into substantially parallel light. The light emitting element 13 is, for example, an LED (Light Emitting Diode).

  Each illumination optical system 20R, 20G, 20B converts incident color light into linearly polarized light that uniformly illuminates the DMDs 50R, 50G, 50B. The illumination optical system 20R and the illumination optical system 20B convert the incident color light into linearly polarized light polarized in a direction perpendicular to the incident surface of the XDP 60, and the illumination optical system 20G converts the incident color light to the incident surface of the XDP 60. On the other hand, it is converted into linearly polarized light polarized in the parallel direction. Each light emitted from each illumination optical system 20 enters each of the TIR prisms 40R, 40G, and 40B.

  As described above, according to the third embodiment of the present invention, the illumination unit 26 includes the plurality of light sources 13R, 13G, and 13B that emit color light. Thereby, since a plurality of light sources are used, the brightness of the projected image can be improved, and a separation optical system that separates white light into a plurality of color lights is not necessary, so that the apparatus size can be reduced. Become. As described above, even in the configuration in which the luminance is improved and the apparatus size is reduced, it is possible to suppress the decrease in the contrast of the projected image.

  While the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  For example, in the first and second embodiments, the light source 10 includes the light source lamp 11 and the reflector 12 that makes the light emitted from the light source lamp 11 substantially parallel light. It is not limited to. For example, the light emitted from the light source lamp 11 may be made substantially parallel light using a lens. In this case, as the light source lamp 11, an LED or a phosphor that emits fluorescence by absorbing excitation energy can be used.

  Moreover, in the said embodiment, although the illumination optical system 20 was set as the structure using the 1st lens array 21, the 2nd lens array 22, the polarization conversion element 23, and the superimposition lens 24, this invention is not limited to this example. . For example, the illumination optical system 20 may be configured using a rod integrator.

  In the above embodiment, the superimposing lens 24 is a single optical component, but the present invention is not limited to such an example. For example, the superimposing lens 24 may be a plurality of lenses in order to improve the performance of the illumination optical system 20 or adjust the apparatus size, and may have a configuration in which a folding mirror is added. .

  Moreover, in the said embodiment, although arrangement | positioning of the correction | amendment optical element of the display apparatus 3 concerning 3rd Embodiment was made the same as that of the display apparatus 1 concerning 1st Embodiment, this invention is not limited to this example. For example, the arrangement of the correction optical elements of the display device 3 can be changed similarly to the second embodiment.

1, 2, 3 Display device 10 Light source unit 11 Light source lamp 12 Reflector 20 Illumination optical system 21 First lens array 22 Second lens array 23 Polarization conversion element 24 Superimposing lenses 25 and 26 Illumination unit 30 Light separation optical system (separation) Part)
31 First dichroic mirror 32 Second dichroic mirror 33, 34, 35 Reflective mirrors 40R, 40G, 40B TIR prism (optical path adjustment unit)
50R, 50G, 50B DMD (light modulator)
60 XDP (synthesis unit)
70R, 70G, 70B Correction optical element (correction unit)
90R, 90G, 90B Correction optical element (correction unit)
80 Projection optical system (projection unit)

Claims (4)

An illumination unit that emits a plurality of colored lights having a predetermined polarization direction;
A plurality of optical path adjustment units that totally reflect the plurality of colored lights, respectively;
A plurality of light modulation units that respectively modulate a plurality of color lights totally reflected by the plurality of optical path adjustment units and emit a plurality of color modulation lights, respectively;
A combining unit that emits a plurality of color-modulated lights emitted from each light modulation unit in the same direction;
A correction unit that is provided on an optical path between the illumination unit and the combining unit, changes a polarization state of incident light, and makes light incident on the combining unit linearly polarized light; and
The correction unit has at least one 1/8 wavelength plate or 5/8 wavelength plate. The combining unit reflects or transmits each color modulated light and emits the same in the same direction,
The correction unit is provided corresponding to each light incident on the combining unit, and the correction unit corresponding to the light reflected by the combining unit is an 1/8 wavelength plate, and is transmitted through the combining unit. The projection type display apparatus according to claim 1, wherein the correction unit corresponding to 1 includes at least one half-wave plate.   The projection display device according to claim 1, wherein the optical path adjustment unit is a TIR prism.   The projection display apparatus according to claim 1, wherein the light modulation unit is a digital micromirror device.

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