JP2006113282A - Projection display - Google Patents

Abstract

The object of the present invention is to improve the angle characteristics of a polarizing beam splitter when the light beam is narrowed down, to realize a projection state in which contrast is enhanced, and to enhance the brightness that projects a large amount of light when the light beam is expanded. PROBLEM TO BE SOLVED: To provide a projection display device that can realize the projected state.
A projection display comprising a light source, a reflector, an illumination optical system, a polarization beam splitter, a reflective liquid crystal display element, and a projection lens, and projects an image formed by the reflective liquid crystal display element onto a projection surface. In the apparatus, the illumination optical system includes a light beam separation unit, a light collection unit, and an aperture stop, and the aperture light makes the spread angle of the illumination light beam by the illumination optical system variable.
[Selection] Figure 1

Description

  The present invention relates to a projection display device using a reflective liquid crystal display element.

  In a projection type display device using a reflective liquid crystal display device, illumination light for illuminating the reflective liquid crystal display element is guided using a polarization beam splitter, and light modulated by the reflective liquid crystal display element is further converted into two polarization beam splitters. Japanese Patent Application Laid-Open No. H10-228707 discloses a configuration for performing light detection using a light source. In Patent Document 1, as shown in FIG. 11, four polarization beam splitters 118, 120, 124, and 128 and three color selective phase difference plates 116, 126, and 134 are configured. Here, the color selective phase difference plate has a function of converting the polarization direction of light in a predetermined wavelength region by 90 degrees in the wavelength region of visible light and not changing the polarization direction of light of other wavelengths.

  In Patent Document 1, linearly polarized light (S-polarized light) from a light source is rotated by 90 degrees (P-polarized light) with only the blue (B) light rotated by the first color-selective retardation plate 116 (P-polarized light). The light is incident on the polarization beam splitter 118, transmits B light that is P-polarized light, and reflects green (G) and red (R) light other than B that is S-polarized light. (P-polarized light) passes through the second polarizing beam splitter 120 and reaches the reflective liquid crystal display element B122, and the GR light is incident on the second color-selective retardation plate 126, and only the polarization direction of G is 90 degrees. It is converted (P-polarized light), and the second polarized beam splitter transmits G light that is P-polarized light and reflects R light that is S-polarized light, so that each light of GR is reflected liquid crystal. It reaches the display element G132 and the reflective liquid crystal display element R130.

  The P-polarized component of the light image-modulated by the reflective liquid crystal display element B122 is transmitted through the second polarizing beam splitter 120 and returns to the light source side, and the S-polarized component is reflected by the second polarizing beam splitter 120 to be projected light. It becomes. The S-polarized component of the light image-modulated by the reflective liquid crystal display element R130 is reflected by the third polarizing beam splitter 128 and returns to the light source side, and the P-polarized component is transmitted through the third polarizing beam splitter 128 to be projected light. Become. The P-polarized component of the light image-modulated by the reflective liquid crystal display element G132 is transmitted through the third polarizing beam splitter 128 and returns to the light source side, and the S-polarized component is reflected by the third polarizing beam splitter 128 to be projected light. Become. The G and R projection light is incident on the third color-selective retardation plate 134, the G polarization direction is rotated by 90 degrees, and the GR light is aligned with the P polarization and transmitted through the fourth polarization beam splitter 124. The S-polarized B light is reflected by the fourth polarizing beam splitter 124, and the RGB light is combined into one to project a color image.

US Pat. No. 6,183,091

  In order to increase the brightness of the projected image light, it is necessary to increase the utilization efficiency of light from the light source to the reflective image display element. For this purpose, it is necessary to reduce the FNO of the illumination system, that is, to increase the angle at which the illumination light beam extends in the reflective image display element.

  Here, when a polarization beam splitter is used in the color synthesis system, the polarization beam splitter exhibits an ideal change separation action as shown in FIG. 12A at a predetermined design incident angle. At the incident angle deviated from the angle, the polarization separation characteristic changes as shown in FIG. This is because the polarization beam splitter in the color synthesizing system also has a function as an analyzer. Therefore, when the polarization separation characteristic is deteriorated, the light intensity is lowered, and the contrast is lowered in the projected image. For this reason, conventionally, the illumination system is configured to illuminate with an illumination light beam with sufficient contrast, and the brightness of the projected image cannot be increased.

  The present invention has been made in view of the above problems, and the purpose of the present invention is to improve the angular characteristics of the polarizing beam splitter when the light beam is narrowed, to realize a projection state with enhanced contrast, and when the light beam is widened. An object of the present invention is to provide a projection display device capable of realizing a projection state in which the brightness for projecting a large amount of light is emphasized.

  In order to achieve the above object, the invention described in claim 1 includes a light source, a reflector, an illumination optical system, a polarizing beam splitter, a reflective liquid crystal display element, and a projection lens, and is formed by the reflective liquid crystal display element. A projection display apparatus that projects an image onto a projection surface, wherein the illumination optical system includes a light beam separating unit, a light collecting unit, and an aperture stop, and the aperture optical stop spreads the illumination light beam by the illumination optical system. The angle is variable.

  The invention described in claim 2 has a light source, a reflector, an illumination optical system, a polarization beam splitter, a reflective liquid crystal display element, and a projection lens, and projects an image formed by the reflective liquid crystal display element onto a projection surface. The illumination optical system includes a light beam separating unit, a light collecting unit, and an aperture stop, and the aperture stop makes a spread angle of the illumination light beam by the illumination optical system 1.3 times or more. It is characterized by being variable.

  According to the present invention, the projection type includes a light source, a reflector, an illumination optical system, a polarization beam splitter, a reflective liquid crystal display element, and a projection lens, and projects an image of the reflective liquid crystal display element onto a projection surface such as a screen. In the display device, the illumination optical system includes a light beam separating unit and a condensing unit, and a reflection type liquid crystal by providing an aperture stop capable of changing an aperture area in an optical path from the light source to the screen. The spread of the light beam collected by the display element can be changed. When the light beam is narrowed, the angle characteristics of the polarizing beam splitter are improved, and a projection state with enhanced contrast can be realized. A projection state in which the brightness for projecting the amount of light is emphasized can be realized.

  Here, the aperture stop is provided at a position where a plurality of light source images generated by the light beam separating means are formed or at a position before and after the light source image so that the illumination light beam acts uniformly on the entire reflective liquid crystal display element. can do.

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

<Embodiment 1>
FIG. 1 is a diagram showing Embodiment 1 of the present invention.

  In the figure, 1 is a light source that emits white light with a continuous spectrum, and 2 is a reflector that condenses light from the light source 1 in a predetermined direction. 3a is a first fly-eye lens in which rectangular lenses are arranged in a matrix, and 3b is a second fly-eye lens having a lens array corresponding to each lens of the first fly-eye lens 3a. S1 is an aperture stop, 4 is a polarization conversion element that aligns unpolarized light with predetermined polarized light, 5a is a condenser lens, 5b is a field lens, and 5c is a reflection mirror.

  6a is a first color-selective retardation plate that converts the polarization direction of R (red) light by 90 degrees and B (blue) light is not converted, and 6b is a polarization direction of R (red) light. Is a second color-selective phase difference plate that converts 90 ° and does not convert the polarization direction of B (blue) light. Reference numeral 7 denotes a third color-selective retardation plate that converts the polarization direction of G (green) light by 90 degrees and does not convert the polarization directions of B and R light. Reference numerals 8a and 8b denote a first half-wave plate and a second half-wave plate. Reference numerals 9a, 9b, 9c, and 9d denote a first polarization beam splitter, a second polarization beam splitter, a third polarization beam splitter, and a fourth polarization beam splitter that transmit P-polarized light and reflect S-polarized light.

  Reference numeral 10 denotes a color filter that cuts light in a wavelength region intermediate between G and R. Reference numerals 11r, 11g, and 11b are a reflective liquid crystal display element for red, a reflective liquid crystal display element for green, and a reflective liquid crystal display element for blue that reflect light and display an image by modulating the image. Reference numerals 12r, 12g, and 12b denote a quarter-wave plate for red, a quarter-wave plate for green, and a quarter-wave plate for blue. Reference numeral 13 denotes a projection lens.

  Next, the optical action will be described.

  Light emitted from the light source 1 is collected in a predetermined direction by the reflector 2. Here, the reflector 2 is formed in a paraboloid shape, and light from the focal position of the paraboloid becomes a light beam parallel to the symmetry axis of the paraboloid. Here, since the light source 1 is not an ideal point light source but has a finite size, the condensed light flux includes many light components that are not parallel to the symmetry axis of the paraboloid. These condensed light beams are incident on the first fly-eye lens 3a. The first fly-eye lens 3a is configured by combining lenses having a positive refractive power having a rectangular outer shape in a matrix shape, and an incident light beam is divided into a plurality of light beams corresponding to each lens, and The light is condensed and passes through the second fly-eye lens 3b to form a plurality of light source images in the vicinity of the polarization conversion element in a matrix.

  The polarization conversion element 4 has a polarization separation surface, a reflection surface, and a half-wave plate, and a plurality of light beams collected in a matrix form enter a polarization separation surface corresponding to the column and transmit the P polarization component. And the S-polarized component light to be reflected. The reflected S-polarized component light is reflected by the reflecting surface, emitted in the same direction as the P-polarized component, transmitted through the half-wave plate and converted into the same polarized component as the P-polarized component, and the polarization direction (|) is changed. It emits as uniform light. The plurality of light beams that have undergone polarization conversion are condensed in the vicinity of the polarization conversion element, and then reach the condensing optical system as divergent light beams.

  The condensing optical system includes a condenser lens 5a and a field lens 5b. A plurality of light beams overlap each other at a position where a fly-eye lens can form a rectangular image by the condensing optical system, thereby forming a rectangular uniform illumination area. Reflective liquid crystal display elements 11r, 11g, and 11b are arranged in this illumination area.

  The third color-selective phase difference plate 7 provided in the illumination optical path has characteristics as indicated by the solid line in FIG. 2, and the B and R light remains P-polarized light (|), and G The light is converted to S-polarized light (•). Here, the polarization direction (·) (|) is expressed as the direction of polarization with respect to the polarization separation surface of the polarization conversion element and the polarization beam splitter.

  The light whose polarization direction is adjusted in the third color selective phase difference plate 7 enters the first polarization beam splitter 9a. The G light that is S-polarized light reflects the polarization separation surface, and the R and B light that is P-polarized light passes through the polarization surface for color separation.

  The color-separated G light is incident on the second polarization beam splitter 9b as S-polarized light (•), reflects off the polarization separation surface, and reaches the G reflective liquid crystal display element 11g. The G light is image-modulated and reflected by the reflective liquid crystal display element 11g for G. The S-polarized component (•) of the reflected light of the image-modulated G is reflected again on the polarization separation surface, returned to the light source side, and removed from the projection light. The P-polarized component (|) of the image-modulated G reflected light is transmitted through the polarization separation surface and becomes projection light. At this time, a quarter-wave plate provided between the second polarizing beam splitter 9b and the reflective liquid crystal display element 11g for G in a state in which all polarized components are converted to S-polarized light (a state in which black is displayed). The slow axis of 12 g is adjusted in a predetermined direction to minimize the influence of the polarization state disturbance generated in the first polarizing beam splitter and the G reflective liquid crystal display element.

  The light (|) that has passed through the second polarizing beam splitter passes through the first half-wave plate 8a that is arranged so that the slow axis is in the direction of 45 degrees with respect to the polarization direction. The light enters the beam splitter as S-polarized light (·), reflects off the polarization separation surface, and reaches the projection lens 13.

  The R and B light (|) transmitted through the first polarizing beam splitter enters the color filter. The color filter has a characteristic as indicated by a solid line in FIG. 3 and is a dichroic filter that reflects yellow color light and unnecessary green color light that fall in the middle wavelength region between G and R. Here, the color filter may have a characteristic of absorbing light.

  The light whose color has been adjusted is incident on the first color selective phase difference plate 6a. The first color-selective retardation plate 6a has the characteristics shown by the dotted line in FIG. 2, and the B light remains P-polarized (|) and the R light is converted to S-polarized (•). Is done. Here, the transition region where the polarization state changes is set to the G region.

  As a result, the B light enters the third polarization beam splitter 9c as P-polarized light (|) and the R light as S-polarized light (·). Therefore, in the third polarizing beam splitter 9c, the B light is transmitted through the polarization separation surface and reaches the B reflective liquid crystal display element 11b, and the R light is reflected from the polarization separation surface and reflected by the R reflection type. It reaches the liquid crystal display element 11r.

  In the reflective liquid crystal display element for B, B light is image-modulated and reflected. The P-polarized light component (|) of the modulated reflected light of B is transmitted again through the polarization separation surface, returned to the light source side, and removed from the projection light. The S-polarized light component (•) of the modulated reflected light of B is reflected by the polarization separation surface and becomes projection light. Similarly, R light is image-modulated and reflected by the reflective liquid crystal display element for R. The S-polarized component (•) of the modulated reflected light of R is reflected again on the polarization separation surface, returned to the light source side, and removed from the projection light. The P-polarized light component (|) of the modulated reflected light of R is transmitted through the polarization separation surface and becomes projection light. As a result, the B and R projection lights are combined into one light beam. At this time, G is adjusted by adjusting the slow axis of the quarter wave plates 12r and 12b provided between the third polarizing beam splitter 9c and the reflective liquid crystal display elements 11r and 11b for R and B. The black display of R and B is adjusted in the same manner as in FIG.

  The combined R and B projection light is incident on the second color selective phase difference plate. The second color-selective phase difference plate is the same as the first color-selective phase difference plate, rotates only the polarization direction of R by 90 degrees, and both R and B are converted to S-polarized light (•). Further, the light is converted into P-polarized light (|) by the half-phase plate 8b having a slow axis in the direction of 45 degrees with respect to the polarization direction, and is incident on the fourth polarization beam splitter 4d and transmitted through the polarization separation surface. Thus, it is synthesized with the G projection light.

  The combined R, G, B projection light is projected onto a screen or the like by a projection lens.

  4A shows a state in which the aperture stop is opened, and FIG. 4B shows a state in which the aperture stop is closed. An L-shaped shading plate is inserted and removed from the side of the fly-eye lens.

  In the state of FIG. 4A, the light beam incident on all the lenses constituting the fly-eye lens passes through the aperture stop and becomes a small FNO illumination light beam. By gradually narrowing down the aperture stop, the number of lenses in the fly-eye lens through which the light beam is transmitted decreases. At this time, it is more desirable that the fly-eye lens can be narrowed down step by step in accordance with the boundary portion of each lens because unnecessary shadows are not generated on the screen.

  As the aperture stop is reduced, the number of fly-eye lenses used decreases, but in order to reduce unevenness in brightness on the projection screen, light beams that have passed through at least about 20 lenses are used. It is better to be.

<Embodiment 2>
FIG. 5 is a diagram showing Embodiment 2 of the present invention.

  In the figure, the same elements as those of the first embodiment are denoted by the same reference numerals, 24 is a polarization conversion element, 25a is a condenser lens, 25b is a field lens, 25c is a reflection mirror, and 26 is blue (B) and red ( A dichroic mirror that transmits light in the wavelength region of R) and reflects light in the wavelength region of green (G), 27 is a color filter that partially cuts light in the wavelength region between G and R, and 28a and 28b are A first color-selective phase plate and a second color-selective phase plate that convert the polarization direction of B light by 90 degrees and do not convert the polarization direction of R light.

  Reference numeral 29 denotes a first half-wave plate, a second half-wave plate, and 30a, 30b, and 30c, a first polarizing beam splitter that transmits P-polarized light and reflects S-polarized light, and a second polarizing beam splitter. The third polarization beam splitter S2 is an aperture stop.

  Next, the optical action will be described.

  Although the polarization conversion element 24 of the present embodiment also has a polarization separation surface, a reflection surface, and a half-wave plate, in this embodiment, the reflected S-polarized component light is reflected by the reflection surface, and P The light is emitted in the same direction as the polarization component. On the other hand, the transmitted P-polarized light component is transmitted through the half-wave plate, converted to the same polarized light component as the S-polarized light component, and emitted as light having the same polarization direction (·).

  The plurality of light beams that have undergone polarization conversion are condensed in the vicinity of the polarization conversion element, and then reach the condensing optical system as divergent light beams. The condensing optical system includes a condenser lens 25a and a field lens 25b, and a plurality of light beams are overlapped at a position where a rectangular image of each lens of the fly-eye lens can be formed by a condensing function, and a rectangular uniform illumination area. Form. Further, the light condensed on the reflective liquid crystal display element in the optical path from the field lens 25b to the reflective liquid crystal display elements 11r, 11g, and 11b is set to be substantially telecentric with respect to the optical axis of the condensing optical system. In addition, the characteristic variation due to the incident angle generated in the optical thin films of the dichroic mirror 6 and the polarization beam splitters 30a and 10b does not appear as an image on the reflective liquid crystal display element.

  The dichroic mirror 26 has a characteristic as shown by a solid line in FIG. 6, and B and R light is transmitted, and G light is reflected. In FIG. 5, the light that has been S-polarized light in the polarization conversion element is also S-polarized light (·) for the dichroic mirror 6.

  In the G optical path, the light reflected by the dichroic mirror 26 enters the color filter 27. The color filter 27 has a characteristic as indicated by a dotted line in FIG. 6, and is a dichroic filter that reflects yellow color light falling in the middle wavelength region between G and R, and removes yellow light. If green light has many yellow color components, green becomes yellowish green. Therefore, it is desirable in terms of color reproduction to remove yellow light.

  The light whose color has been adjusted is incident on the first polarization beam splitter 30a as S-polarized light (.), Reflected by the polarization separation surface, and reaches the G reflective liquid crystal display element 11g. The G light is image-modulated and reflected by the reflective liquid crystal display element 11g for G. The S-polarized component (•) of the modulated reflected light of G is reflected again by the polarization separation surface, returned to the light source side, and removed from the projection light. The P-polarized light component (|) of the modulated reflected light of G is transmitted through the polarization separation surface and becomes projection light. At this time, a quarter-wave plate provided between the first polarizing beam splitter 30a and the reflective liquid crystal display element 11g for G in a state in which all polarization components are converted to S-polarized light (a state in which black is displayed). The slow axis of 12g is adjusted to a predetermined direction, and the influence of the disturbance of the polarization state generated in the first polarizing beam splitter 30a and the reflective liquid crystal display element 11g for G is suppressed to be small.

  The light (|) transmitted through the first polarizing beam splitter 30a is rotated by 90 degrees in the polarization direction by the first half-wave plate 29 whose slow axis is set at 45 degrees with respect to the polarization direction. 3 enters the polarizing beam splitter 30c as S-polarized light (·), is reflected by the polarization separation surface, and reaches the projection lens 13.

  The R and B lights transmitted through the dichroic mirror 26 are incident on the first color selective phase difference plate 8a. The first color-selective retardation plate 28a has a function of rotating only the B light by 90 degrees in the polarization direction, so that the B light becomes P-polarized light (|) and the R light becomes S-polarized light (. ) Enters the second polarizing beam splitter 30b. Therefore, in the second polarization beam splitter 30b, the B light passes through the polarization separation surface and reaches the B reflective liquid crystal display element 11b, and the R light reflects off the polarization separation surface and reflects to the R reflection type liquid crystal display element 11b. It reaches the liquid crystal display element 11r.

  The B light is image-modulated and reflected by the B reflective liquid crystal display element 11b. The P-polarized light component (|) of the modulated reflected light of B is transmitted again through the polarization separation surface, returned to the light source side, and removed from the projection light. The S-polarized light component (•) of the modulated reflected light of B is reflected by the polarization separation surface and becomes projection light. Similarly, the R light is image-modulated and reflected by the R reflective liquid crystal display element 11r. The S-polarized component (•) of the modulated reflected light of R is reflected again on the polarization separation surface, returned to the light source side, and removed from the projection light. The P-polarized light component (|) of the modulated reflected light of R is transmitted through the polarization separation surface and becomes projection light. As a result, the B and R projection lights are combined into one light beam. At this time, G is adjusted by adjusting the slow axis of the quarter wave plates 12r and 12b provided between the second polarizing beam splitter 30b and the reflective liquid crystal display elements 11r and 11b for R and B. The black display of R and B is adjusted in the same manner as in FIG.

  The combined R and B projection light is incident on the second color selective phase difference plate 8b. The second color-selective phase difference plate 8b is the same as the first color-selective phase difference plate 28a and rotates only the polarization direction of B by 90 degrees. The light is incident on the polarization beam splitter 30c and transmitted through the polarization separation surface, and is combined with the G projection light.

  The combined R, G, B projection light is projected onto a screen or the like by the projection lens 13.

  FIG. 7A shows a state where the aperture stop is opened, and FIG. 7B shows a state where the aperture stop is closed. In this configuration, an L-shaped light shielding plate is inserted and removed in the vicinity of the aperture position of the projection lens in the projection lens barrel.

<Embodiment 3>
FIG. 8 is a diagram showing Embodiment 3 of the present invention. In FIG. 8, the same elements as those of the second embodiment are denoted by the same reference numerals, S3 is an aperture stop, 35a is a first condenser lens, 35b is a second condenser lens, and 35c and 35c ′ are It is a field lens. 36 is a dichroic mirror that transmits light in the blue (B) and green (G) wavelength regions and reflects light in the red (R) wavelength region, and 37 is a part of light in the middle wavelength region between G and R. It is a color filter to cut.

  Reference numerals 38 and 38b denote a first color selective phase difference plate and a second color selective phase difference plate that change the polarization direction of the G light by 90 degrees and do not convert the polarization direction of the B light. Reference numeral 39 denotes a polarizing plate that reflects a predetermined polarization component and transmits a polarization component orthogonal thereto. Here, the polarizing plate may absorb an unnecessary polarization direction. The dichroic mirror 36 is provided between the second condenser lens 35b and the field lenses 35c and 35d constituting the condensing optical system.

  Next, the optical action will be described.

  The light emitted from the polarization conversion element 24 is collected by the first condenser lens 35 a and the second condenser lens 35 b and enters the dichroic mirror 36. The dichroic mirror 36 has characteristics as indicated by the solid line in FIG. 9, and B and G light is transmitted, while R light is reflected.

  In FIG. 8, the light that was S-polarized light (•) in the polarization conversion element 24 is also S-polarized light (•) for the dichroic mirror 36. However, in the present embodiment, since the dichroic mirror 36 is provided between the second condenser lens 35b and the field lenses 35c and 35c ', the light flux acting on the dichroic mirror 36 is not telecentric. Therefore, the dichroic mirror 36 is configured so that the film thickness gradually increases in the direction from A to B in the drawing, and the change in characteristics due to the incident angle is corrected.

  In the R optical path, the light reflected by the dichroic mirror 36 passes through the field lens 35 c and enters the color filter 37. The color filter has a characteristic as indicated by a dotted line in FIG. 9 and is a dichroic filter that reflects yellow color light falling in the middle wavelength region between G and R, and removes yellow light. If red light has many yellow color components, red becomes orange. Therefore, it is desirable to remove yellow light in terms of color reproduction.

  Here, the color filter 37 is provided separately from the field lens 35c ', but may be provided on the lens surface of the field lens 35c'.

  The light whose color has been adjusted enters the first polarizing beam splitter 30a as S-polarized light (•), is reflected by the polarization separation surface, and reaches the R reflective liquid crystal display element. The R light is image-modulated and reflected by the R reflective liquid crystal display element 11r. The S-polarized component (•) of the modulated reflected light of R is reflected again by the polarization separation surface, returned to the light source side, and removed from the projection light. The P-polarized light component (|) of the modulated reflected light of R is transmitted through the polarization separation surface and becomes projection light. The light transmitted through the first polarization beam splitter 30a is rotated by 90 degrees in the polarization direction by the first half-wave plate 39a, and is incident on the third polarization beam splitter 30c as S-polarized light (·). The light is reflected by the polarization separation surface and reaches the projection lens 13.

  The G and B lights that have passed through the dichroic mirror 36 pass through the field lens 35 d and enter the polarizing plate 39. The polarizing plate 29 has a characteristic of transmitting a polarization component that is an S polarization component to the dichroic mirror 36 and reflecting a polarization component that is a P polarization component. The light (·) whose polarization components are more aligned by the polarizing plate 39 is incident on the first color-selective retardation plate 38a. The first color-selective retardation plate 38a has a function of rotating the polarization direction of the G light by 90 degrees, whereby the G light becomes P-polarized light (|) and the B light becomes S-polarized light (. ) Enters the second polarizing beam splitter 30b.

  The B light is image-modulated and reflected by the B reflective liquid crystal display element 11b. The S-polarized component (•) of the modulated B reflected light is reflected again from the polarization separation surface, returned to the light source side, and removed from the projection light. The P-polarized light component (|) of the modulated reflected light of B is transmitted through the polarization separation surface and becomes projection light. Similarly, G light is image-modulated and reflected by the reflective liquid crystal display element 11g for G. The P-polarized light component (|) of the modulated G reflected light is again transmitted through the polarization separation surface, returned to the light source side, and removed from the projection light. The S-polarized light component (•) of the modulated reflected light of G is reflected on the polarization separation surface and becomes projection light. As a result, the B and G projection lights are combined into one light beam.

  The combined G and B projection light enters the second color-selective phase difference plate 28b. The second color-selective phase difference plate 28b is the same as the first color-selective phase difference plate 28a, and rotates only the polarization direction of G by 90 degrees, and both G and B are P-polarized light (|). The light is incident on the polarization beam splitter 10c and passes through the polarization separation surface, and is combined with the R projection light.

  Here, the quarter-wave plates 12g and 12b provided between the second polarizing beam splitter 30b and the reflective liquid crystal display elements 11g and 11b for G and B can rotate the direction of the slow axis. Thus, the disturbance of the polarization state generated in the second polarizing beam splitter 10b and the respective reflective liquid crystal display elements 11g and 11b is adjusted.

  FIG. 10a shows a state where the aperture stop is opened, and FIG. 10b shows a state where the aperture stop is closed. The light-shielding plate having the rectangular opening shape is inserted and removed on the emission side of the reflector.

  At this time, the light shielding plate is a reflecting mirror, and may have a so-called recursive effect of returning the light component to be shielded to the light source.

It is a figure explaining Embodiment 1 of this invention. It is a figure explaining the characteristic of a wavelength selective phase difference plate. It is a figure explaining the characteristic of a dichroic mirror and a color filter. It is a figure explaining the aperture stop of Embodiment 1 of this invention. It is a figure explaining Embodiment 2 of this invention. It is a figure explaining the characteristic of a dichroic mirror and a color filter. It is a figure explaining the aperture stop of Embodiment 2 of this invention. It is a figure explaining Example 3 of this invention. It is a figure explaining the characteristic of a dichroic mirror and a color filter. It is a figure explaining the aperture stop of Embodiment 3 of this invention. It is a figure explaining a prior art example. It is a figure explaining the polarization splitting characteristic of a polarization beam splitter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Reflector 3a 1st fly eye lens 3b 2nd fly eye lens 5a Condenser lens 5b Field lens 9a-9d 1st-4th polarizing beam splitter 11r, 11g, 11b For red, green, and blue Reflective liquid crystal display element 13 Projection lens S1 Aperture stop

Claims (2)

A projection display device that has a light source, a reflector, an illumination optical system, a polarizing beam splitter, a reflective liquid crystal display element, and a projection lens, and projects an image formed by the reflective liquid crystal display element onto a projection surface. ,
The illumination optical system includes a light beam separating unit, a condensing unit, and an aperture stop, and a projection display device characterized in that a spread angle of an illumination light beam by the illumination optical system is variable by the aperture stop. A projection display device that has a light source, a reflector, an illumination optical system, a polarizing beam splitter, a reflective liquid crystal display element, and a projection lens, and projects an image formed by the reflective liquid crystal display element onto a projection surface. ,
The illumination optical system includes a light beam separating unit, a condensing unit, and an aperture stop, and a projection type in which a spread angle of the illumination light beam by the illumination optical system is variable by 1.3 times or more by the aperture stop. Display device.

Images