JP2005283658A - Image projecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent image projecting device capable of accurately and easily adjusting the positional relationship of projected light. <P>SOLUTION: The image projecting device projecting an image based on an inputted video signal to a screen is equipped with a light source for emitting illuminating light, 1st and 2nd spatial modulation means 10a to 18a and 10b to 18b generating the projected light being linearly polarized light by modulating the illuminating light based on the inputted video signal, an optical path composing means 22 composing the projected light generated by the 1st and the 2nd spatial modulation means by using a property that their polarization directions are orthogonal to each other, an optical path separating means 22 separating a part of the projected light in composing the projected light by the optical path composing means, a projecting optical means 36 projecting the projected light composed by the optical path composing means to the screen, and a monitor image pickup means 50 picking up the projected light separated by the optical path separating means as a monitor image. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image projection apparatus using a plurality of projectors.

  In an image projection apparatus using a plurality of projectors, since the projection light from each projector is synthesized on the screen, it is necessary to accurately adjust the positional relationship of the projection light from each projector.

  As a conventional technique, Patent Document 1 proposes a method in which image light of a plurality of display images is reflected by a composite reflection surface, and the image light reflected by each composite reflection surface is projected through one optical system. ing. However, in this proposal, if the positional relationship between the plurality of display images is deviated, an appropriate projection image cannot be maintained.

  Patent Document 2 proposes a method in which a plurality of projectors are mounted on a stage, a projected image from each projector is photographed by a camera, and the positional relationship of the projectors is adjusted based on the photographing result. However, in this proposal, since projection is performed via separate projection optical systems, proper display and proper correction cannot be performed unless the characteristics of the projection optical systems are the same.

  Patent Document 3 proposes a method of combining projection light from a plurality of projectors with a polarization beam splitter (PBS) and projecting the combined projection light onto a screen. However, this proposal does not describe a method for adjusting the positional relationship of projection light from a plurality of projectors, and a normal projection image cannot be maintained if the positional relationship of projection light deviates.

Patent Document 4 discloses a method of projecting images displayed on a plurality of spatial modulation means onto a screen, photographing the projected image with a camera, and adjusting the positional relationship of the spatial modulation means based on the photographing result. Has been proposed. However, in this proposal, the spatial modulation means itself must have an adjustment function.
JP-A-8-240786 JP-A-8-168039 JP-A-5-224321 Japanese Patent No. 297239

  As described above, in the image projection apparatus using a plurality of projectors, it is necessary to adjust the positional relationship of the projection light from each projector. However, in the conventional image projection device, the positional relationship of each projection light can be accurately and easily simplified. Therefore, it is difficult to obtain an inexpensive image projection apparatus with excellent display quality.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide an excellent image projection apparatus capable of easily and accurately adjusting the positional relationship of projection light.

  An image projection apparatus according to the present invention is an image projection apparatus that projects an image based on an input video signal onto a screen, and modulates the illumination light based on a light source that emits illumination light and an input video signal. The first and second spatial modulation means for generating projection light that is linearly polarized light and the projection light generated by the first and second spatial modulation means have the property that their polarization directions are orthogonal to each other. An optical path combining unit for combining the optical signals, an optical path separating unit for separating a part of the projection light when the projection light is combined by the optical path combining unit, and a projection for projecting the projection light combined by the optical path combining unit onto the screen. It is characterized by comprising optical means and monitor image imaging means for imaging the projection light separated by the optical path separating means as a monitor image.

  The image projection apparatus further includes a position adjusting unit that adjusts a position of at least one of the first and second spatial modulation units with respect to the optical path combining unit based on a monitor image captured by the monitor image capturing unit. It is preferable.

  In the image projection apparatus, a difference between an image generated by the first spatial modulation unit and an image generated by the second spatial modulation unit is detected from a monitor image captured by the monitor image imaging unit. It is preferable to further include a difference detection means.

  The image projection apparatus preferably further includes difference detection means for detecting a difference between a predetermined image to be formed as a monitor image based on the video signal and the monitor image picked up by the monitor image pick-up means. .

  The image projection apparatus further includes a position adjustment unit that adjusts a position of at least one of the first and second spatial modulation units with respect to the optical path combining unit based on the difference detected by the difference detection unit. preferable.

  In the image projection apparatus, it is preferable that the video signal input when the position adjusting unit performs position adjustment is a video signal of a test pattern for detecting the difference.

  In the image projection apparatus, it is preferable that the position adjustment by the position adjustment unit is performed when the image projection apparatus is activated.

  In the image projection apparatus, it is preferable that the video signal of the test pattern is input to the first spatial modulation unit and the second spatial modulation unit in a time division manner.

  In the image projection apparatus, the test pattern video signal input to the first spatial modulation means and the test pattern video signal input to the second spatial modulation means have different test pattern shapes. It is preferable that they are set as follows.

  In the image projection apparatus, the test pattern video signal input to the first spatial modulation means and the test pattern video signal input to the second spatial modulation means have different test pattern colors. It is preferable that they are set as follows.

  In the image projection apparatus, the test pattern video signal input to the first and second spatial modulation means is a green test pattern video signal, and the position adjustment means is the green test pattern. It is preferable to adjust the position of at least one of the first and second spatial modulation means with respect to the optical path combining means based on the monitor image.

  In the image projection apparatus, it is preferable that the video signal of the test pattern is input during a predetermined period in which the video signal of the video to be presented to the viewer is not input.

  In the image projection apparatus, the predetermined period is preferably a horizontal blanking period or a vertical blanking period of a video signal of a video to be presented to the viewer.

  In the image projection apparatus, the difference detected by the difference detection unit is a light amount difference, and the first and second optical paths are separated between at least one of the first and second spatial modulation units and the optical path separation unit. It is preferable to further include a light amount adjusting unit that adjusts the light amount of the projection light generated by at least one of the two spatial modulation units based on the light amount difference.

  In the image projection apparatus, it is preferable that the light amount adjusting unit performs light amount adjustment based on a temporal light amount change of the monitor image captured by the monitor image capturing unit.

  In the image projection apparatus, it is preferable that the light amount adjusting unit performs light amount adjustment based on a light amount of the monitor image corrected based on optical characteristics of the optical path separating unit.

  In the image projection apparatus, it is preferable that the light amount adjusting unit includes an ND filter for adjusting the light amount.

  In the image projection apparatus, each of the first and second spatial modulation units includes at least one spatial modulation element, and the monitor image capturing unit forms an image on a plane conjugate with a display surface of the spatial modulation element. It is preferable to capture the monitor image.

  In the image projection apparatus, each of the first and second spatial modulation units includes a plurality of spatial modulation elements corresponding to a plurality of colors, and one of the first and second spatial modulation units is a predetermined one. A spatial light modulator that rotates the polarization direction of the projection light from the spatial light modulator corresponding to the color, and the other of the first and second spatial light modulators corresponds to a color other than the predetermined color It is preferable to have an optical rotation plate that rotates the polarization direction of the projection light from.

  In the image projection apparatus, each of the first and second spatial modulation means rotates a plurality of spatial modulation elements corresponding to a plurality of colors and a polarization direction of projection light from the spatial modulation element corresponding to a predetermined color. It is preferable that one of the first and second spatial modulation means further includes a λ / 2 plate that rotates the polarization direction of the projection light from the optical rotatory plate.

  In the image projection apparatus, the first spatial modulation unit and the first optical path synthesis unit and the second spatial modulation unit and the optical path synthesis unit, respectively. It is preferable to further include polarization conversion means capable of turning the polarization direction of the projection light from the two spatial modulation means.

  In the image projection apparatus, it is preferable that the polarization conversion unit rotates the polarization direction of the projection light by 90 degrees when a video signal of a test pattern is input.

  In the image projection apparatus, the optical path synthesizing unit includes a polarization beam splitter, and the first and second spatial modulation units are modulated by at least one spatial modulation element and the at least one spatial modulation element, respectively. And a relay optical system for guiding the projected light to the polarizing beam splitter.

  In the image projection apparatus, the optical path synthesizing unit includes a polarization beam splitter, and the projection light generated by one of the first and second spatial modulation units is S-polarized light, and the first and second spatial modulations. The projection light generated by the other of the means is P-polarized light, and the projection optical means transmits the S-polarized projection light reflected by the polarization separation surface of the polarization beam splitter and the polarization separation surface of the polarization beam splitter. It is preferable that the P-polarized projection light is projected onto the screen.

  In the image projection apparatus, the optical path separation unit is configured by the polarization beam splitter, and the monitor image imaging unit includes the S-polarized leakage light transmitted through the polarization separation surface of the polarization beam splitter, and the polarization beam splitter. It is preferable that the P-polarized leaked light reflected by the polarization separation plane is captured as the monitor image.

  In the image projection apparatus, it is preferable that the monitor image capturing unit captures four corners of the monitor image.

  In the image projection apparatus, it is preferable that the monitor image capturing unit includes four image sensors, and four corners of the monitor image are respectively captured by the four image sensors.

  In the image projection apparatus, it is preferable that the monitor image capturing unit includes one image sensor, and four corners of the monitor image are simultaneously captured by the one image sensor.

  In the image projection apparatus, the light beam of the projection light directed to the screen is shifted between the optical path synthesis unit and the projection optical unit in synchronization with the modulation timing of the first and second spatial modulation units, or It is preferable to further include a light beam shift means for switching to two states of not shifting.

  In the image projection apparatus, the light beam shift means includes a liquid crystal panel capable of rotating the polarization direction of the projection light, and transmission that is shifted from the extension line of the incident light when the incident light is polarized in a specific direction. Preferably, the liquid crystal panel rotates the polarization direction of the projection light in synchronization with the modulation timing of the first and second spatial modulation means.

  According to the present invention, the projection light from the first and second spatial modulation means is synthesized by the optical path synthesis means and separated by the optical path separation means, so that the positional relationship and the like of the projection light can be adjusted easily and accurately. Therefore, it is possible to obtain an inexpensive image projection apparatus with excellent display quality.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing a use state of the image projection apparatus according to the first embodiment of the present invention.

  As shown in FIG. 1, a desired image can be obtained on the screen 2 by projecting an image (projection light) onto the screen 2 from an image projection apparatus 1 having a plurality of projectors.

  2 and 3 are diagrams schematically illustrating the overall configuration of the image projection apparatus according to the first embodiment of the present invention.

  A projector 10a and a projector 10b are accommodated in the image projection apparatus 1, and the projector 10a and the projector 10b modulate illumination light based on the input video signal to generate projection light that is linearly polarized light. . The projector 10b is placed on the linear stage 12, and the positional relationship between the projector 10a and the projector 10b can be adjusted by adjusting the linear stage 12 by a method described later. In the example shown in the figure, only the projector 10b is placed on the linear stage 12, but the projector 10a may also be placed on another linear stage independent of the linear stage 12.

  The projection light from the projector 10a is supplied to the polarization beam splitter (PBS) 22 via the optical rotation plate (polarization conversion means) 14a, the polarizing plate 16a, the relay optical system 18a, and the reflection mirror 20, and the projection light from the projector 10b is supplied. , An optical rotation plate (polarization conversion means) 14b, a polarizing plate 16b, and a relay optical system 18b. The projector 10a, the optical rotation plate 14a, the polarizing plate 16a, and the relay optical system 18a constitute one spatial modulation means, and the projector 10b, the optical rotation plate 14b, the polarizing plate 16b, and the relay optical system 18b constitute the other spatial modulation means. . The optical path length from the projector 10a to the polarizing beam splitter 22 and the optical path length from the projector 10b to the polarizing beam splitter 22 are set to be equal to each other.

  FIG. 4 is a diagram schematically showing a configuration example of the above-described spatial modulation means.

  A light source 102 is provided in the projector 10 (projector 10a or projector 10b shown in FIGS. 2 and 3), and illumination light from the light source 102 is dichroic via an illumination optical system 104 including a fly-eye lens or the like. Supplied to the mirror 106. The illumination light that has reached the dichroic mirror 106 reflects the red (R) component and transmits the green (G) component and the blue (B) component. The light transmitted through the dichroic mirror 106 is reflected by the mirror 108 and reaches the dichroic mirror 110. The dichroic mirror 110 reflects the green (G) component and transmits the blue (B) component.

  The R light from the dichroic mirror 106 is supplied to a polarization beam splitter (PBS) 112R. In the polarization beam splitter 112R, the S polarization component is reflected and the P polarization component is transmitted through the polarization separation surface 114R. The P-polarized projection light transmitted through the polarization separation surface 114R is spatially modulated by a reflective liquid crystal display element (reflective LCD) 116R constituting a spatial modulation element. The S-polarized projection light spatially modulated by the reflective LCD 116R is reflected by the polarization separation surface 114R and supplied to the dichroic prism 118.

  The G light from the dichroic mirror 110 is supplied to the polarization beam splitter 112G. In the polarization beam splitter 112G, the S polarization component is reflected and the P polarization component is transmitted through the polarization separation surface 114G. The S-polarized projection light reflected by the polarization separation surface 114G is spatially modulated by the reflective LCD 116G constituting the spatial modulation element. The P-polarized projection light spatially modulated by the reflective LCD 116G passes through the polarization separation surface 114G and is supplied to the dichroic prism 118.

  The B light from the dichroic mirror 110 is supplied to a polarization beam splitter (PBS) 112B. In the polarization beam splitter 112B, the S polarization component is reflected and the P polarization component is transmitted through the polarization separation surface 114B. The P-polarized projection light transmitted through the polarization separation surface 114B is spatially modulated by the reflective LCD 116B constituting the spatial modulation element. The S-polarized projection light spatially modulated by the reflective LCD 116 </ b> B is reflected by the polarization separation surface 114 </ b> B and supplied to the dichroic prism 118.

  In this way, the S-polarized light is supplied to the dichroic prism 118 for the projection light (R light) for the R image and the projection light (B light) for the B image, and the P-polarization is supplied for the projection light (G light) for the G image. Will be. In the dichroic prism 118, the R light, the G light, and the B light are combined, and the combined image light is combined with the optical rotation plate 14 (the optical rotation plate 14a or the optical rotation plate 14b shown in FIGS. 2 and 3) and the polarizing plate 16 ( The light is supplied to the relay optical system 18 (the relay optical system 18a or the relay optical system 18b shown in FIGS. 2 and 3) via the polarizing plate 16a or the polarizing plate 16b shown in FIGS. The relay optical system 18 has a condenser lens and the like, and converts the projection light from the polarizing plate 16 into substantially parallel light and emits it.

  The spatial modulation unit shown in FIG. 4 uses a reflective LCD as the spatial modulation element, but the spatial modulation unit may be configured by using a transmissive LCD as the spatial modulation element.

  FIG. 5 is a diagram for explaining the functions of the optical rotatory plates 14a and 14b, the polarizing plates 16a and 16b, the polarizing beam splitter 22, and the like shown in FIGS. For convenience of explanation, the relay optical systems 18a and 18b and the reflection mirror 20 shown in FIGS. 2 and 3 are not shown.

  As described above, the projectors 10a and 10b emit S-polarized projection light for the R and B images, and P-polarized projection light for the G image. In the optical rotatory plate 14a, the P-polarized G light is rotated and converted into S-polarized light, and the S-polarized R light and B light are transmitted without being rotated. As a result, S-polarized projection light is emitted from the optical rotation plate 14a for all of the R light, G light, and B light. The degree of polarization of S-polarized light from the optical rotatory plate 14a is increased by the polarizing plate 16a. In the optical rotatory plate 14b, the S-polarized R light and the B light are rotated and converted to P-polarized light, and the P-polarized G light is transmitted as it is without rotating. As a result, P-polarized projection light is emitted from the optical rotation plate 14b for all of R light, G light, and B light. The degree of polarization of the P-polarized light from the optical rotatory plate 14b is increased by the polarizing plate 16b.

  In this way, S-polarized image light (projection light) is output from the polarizing plate 16a, and P-polarized image light (projection light) is output from the polarizing plate 16b via the relay optical system (not shown). It is supplied to the splitter 22. As already described, the relay optical system 18 converts the light from the polarizing plate 16 into substantially parallel light and emits it, so that the polarization beam splitter 22 is substantially perpendicular to the incident surface (90 ° ± 5 ° or less). ) Projection light enters. The S-polarized component from the polarizing plate 16 a is reflected by the polarization separation surface 24 of the polarizing beam splitter 22, and the P-polarized component from the polarizing plate 16 b is transmitted through the polarization separation surface 24 of the polarizing beam splitter 22. In this way, in the polarization beam splitter 22, the optical paths of the S-polarized projection light and the P-polarized projection light are synthesized using the property that their polarization directions are orthogonal to each other, and the synthesized projection light is transmitted from the polarization beam splitter 22. Emitted.

  As described above, the polarization beam splitter 22 has a function of reflecting S-polarized light and transmitting P-polarized light on the polarization separation surface 24. However, in practice, not all S-polarized light components are reflected by the polarization separation surface 24, and there are S-polarized light components (leakage light) that pass through the polarization separation surface 24. Similarly, not all P-polarized light components are transmitted through the polarization separation surface 24, and there are P-polarized light components (leakage light) reflected by the polarization separation surface 24. That is, the polarization beam splitter 22 also has a function of separating a part of the projection light as leakage light when synthesizing the projection light. It is possible to form a monitor image using this separation function and adjust the position of the projection image using this monitor image. This adjustment method will be described later.

  The projection light combined by the polarization beam splitter 22 is supplied to the light beam shift means 30, as shown in FIGS. The light beam shifting means 30 is composed of a polarization rotation liquid crystal panel 32 capable of rotating polarized light and a birefringence plate 34 having birefringence. The projection light from the light beam shifting means 30 is projected on the screen via the projection optical system 36.

  FIG. 6 is a diagram showing the principle of the light beam shift means 30.

  The polarization rotation liquid crystal panel 32 is configured to control the rotation of polarization by turning on and off the applied voltage. That is, when the voltage applied to the liquid crystal panel 32 is off, the P-polarized light does not rotate but passes through the liquid crystal panel 32 as it is P-polarized, and similarly, the S-polarized light does not rotate and remains as S-polarized. Pass through. When the voltage applied to the liquid crystal panel 32 is on, the P-polarized light is turned to S-polarized light, and the S-polarized light is turned to P-polarized light. The birefringent plate 34 has a function of shifting incident light with respect to P-polarized light and generating transmitted light deviated from the extended line of the incident light. Moreover, it has the function to permeate | transmit incident light with respect to S polarization | polarized-light, without shifting. As will be described later, the shift amount is ½ pixel pitch, and the shift amount can be determined by the material and thickness of the birefringent plate 34.

  Since the light shifting means 30 has the above-described function, when the voltage applied to the liquid crystal panel 32 is off, the projection light based on the image generated by the projector 10a as shown in FIG. The S-polarized light passes through the liquid crystal panel 32 without being swung by the liquid crystal panel 32, and passes through the birefringent plate 34 without being shifted by the birefringent plate 34. Further, the P-polarized light of the projection light based on the image generated by the projector 10 b passes through the liquid crystal panel 32 without being swung by the liquid crystal panel 32 and is shifted in the vertical direction by the birefringent plate 34.

  On the other hand, when the voltage applied to the liquid crystal panel 32 is on, the S-polarized light of the projection light based on the image generated by the projector 10a is turned to the P-polarized light by the liquid crystal panel 32 as shown in FIG. The P-polarized light from the liquid crystal panel 32 is shifted in the vertical direction by the birefringent plate 34. Further, the P-polarized light of the projection light based on the image generated by the projector 10b is rotated to the S-polarized light by the liquid crystal panel 32, and the S-polarized light from the liquid crystal panel 32 passes through the birefringent plate 34 without being shifted.

  FIG. 7 is a diagram showing the pixel arrangement of the images generated by the projector 10a and the projector 10b before and after the shift operation by the light beam shift means 30. FIG. FIG. 7A shows a case where the applied voltage of the liquid crystal panel 32 is off, and FIG. 7B shows a case where the applied voltage of the liquid crystal panel 32 is on.

  In this embodiment, the pixel position before the image shift operation by the projector 10a (PJA) and the pixel position before the image shift operation by the projector 10b (PJB) are shifted from each other by 1/2 pixel pitch in the horizontal direction. A projector 10a and a projector 10b are arranged.

  When the applied voltage of the liquid crystal panel 32 is off, the projection light based on the image generated by the projector 10a (PJA) is not shifted by the birefringent plate 34 as described above. On the other hand, the projection light based on the image generated by the projector 10b (PJB) is shifted in the vertical direction by the ½ pixel pitch by the birefringent plate. As a result, as indicated by the solid line in FIG. 7A, the pixel position of the image by the projector 10a (PJA) and the pixel position of the image by the projector 10b (PJB) are both horizontal and vertical on the screen surface. , They are shifted from each other by ½ pixel pitch.

  When the applied voltage of the liquid crystal panel 32 is on, the projection light (PJB) based on the image generated by the projector 10b is not shifted by the birefringent plate 34 as described above. On the other hand, the projection light based on the image generated by the projector 10a (PJA) is shifted in the vertical direction by a ½ pixel pitch by the birefringent plate. As a result, as indicated by the solid line in FIG. 7B, the pixel position of the image by the projector 10a (PJA) and the pixel position of the image by the projector 10b (PJB) are both horizontal and vertical on the screen surface. , They are shifted from each other by ½ pixel pitch.

  As can be seen from the above description, whether the incident light is shifted or not can be controlled according to the polarization direction of the incident light to the light beam shift means 30 by switching the liquid crystal panel 32 on and off. . Accordingly, the on / off of the liquid crystal panel 32 is temporally switched in synchronization with the modulation timing of the spatial modulation element (reflection type LCD) of the projector 10a and the spatial modulation element (reflection type LCD) of the projector 10b. The display state shown in FIG. 7A and the display state shown in FIG. 7B can be combined in the time axis direction. That is, one frame period is divided into two field periods, the display state as shown in FIG. 7A is set in the first field, and the display state as shown in FIG. 7B is set in the second field. Set.

  FIG. 8 is a diagram for explaining the above-described operation. FIG. 8A shows the display state of the first field, and FIG. 8B shows the display state of the second field. By combining the display state shown in FIG. 8A and the display state shown in FIG. 8B in the time axis direction, a display state as shown in FIG. 8C can be realized. That is, by using two projectors, it is possible to realize an image projection apparatus having substantially four times the number of pixels of a single projector.

  As already described, the polarization beam splitter 22 separates the leakage light of the S polarization component and the leakage light of the P polarization component. In the present embodiment, a monitor image is formed using the leaked light, and the position of the projected image is adjusted using the monitor image. Hereinafter, this adjustment method will be described.

  At the time of adjustment, as shown in FIGS. 2 and 3, a test pattern for forming a monitor image is projected from the projector 10a and the projector 10b based on an instruction from the image reproduction unit 54. As already described, in the projection light of the test pattern from the projector 10a, the S-polarized component reaches the polarization separation surface 24 of the polarization beam splitter 22, and a part of the light passes through the polarization separation surface 24 as leakage light. In the projection light of the test pattern from the projector 10b, the P-polarized component reaches the polarization separation surface 24 of the polarization beam splitter 22, and a part thereof is reflected on the polarization separation surface 24 as leakage light.

  The leaked light from the polarization beam splitter 22 is guided to the monitor optical system 46 via the optical aperture 42 and the reflection mirror 44 and projected onto the monitor screen 48. The monitor screen 48 is disposed at a position conjugate with the display surface of the spatial modulation element (reflection type LCD 116R, 116G, 116B shown in FIG. 4). The image (monitor image) of the leaked light projected on the monitor screen 48 is captured by the monitor image capturing means 50 including a CCD or the like. Image information of the monitor image captured by the monitor image capturing means 50 is sent to the image processing circuit 52.

  FIG. 9 shows an example of a test pattern imaged on the monitor screen 48, and the test patterns are projected on the four corners of the monitor screen 48. In this example, the shape of the test pattern projected from the projector 10a (PJA) and the shape of the test pattern projected from the projector 10b (PJB) are set to be different from each other. That is, the video signal of the test pattern input to the projector 10a is different from the video signal of the test pattern input to the projector 10b. Thereby, the monitor image by the projector 10a and the monitor image by the projector 10b can be easily identified.

  The color of the test pattern projected from the projector 10a and the color of the test pattern projected from the projector 10b may be set to be different from each other. Also in this case, the monitor image by the projector 10a and the monitor image by the projector 10b can be easily identified.

  Further, the color of the test pattern projected from the projector 10a and the projector 10b may be green. That is, the video signal of the test pattern input to the projector 10a and the projector 10b may be a video signal of the test pattern for green. In general, since human visual sensitivity is high in green (G), it is possible to perform effective adjustment corresponding to human visual sensitivity by using a G image as a test pattern.

  FIG. 10 is a diagram showing the projection timing of the test pattern from the projector 10a and the projector 10b.

  As shown in FIG. 10, from the projector 10a (PJA) and the projector 10b (PJB), a test pattern video is projected in a time-division manner during a predetermined period other than the period during which the video to be presented to the viewer is projected. . That is, the video signal of the test pattern is input to the projector 10a and the projector 10b in a time division manner during a predetermined period in which the video signal of the video to be presented to the viewer is not input. Specifically, the video signal of the test pattern is input to the projector 10a and the projector 10b during the horizontal blanking period or the vertical blanking period.

  In this way, by using the horizontal or vertical blanking period, it is possible to display the test pattern with almost no influence on the video to be presented to the viewer. In addition, by inputting a test pattern video signal to the projector 10a and the projector 10b in a time-sharing manner, the monitor image by the projector 10a and the monitor image by the projector 10b can be easily identified.

  The monitor image of the test pattern projected onto the monitor screen 48 as described above is picked up by the CCD provided in the monitor image pickup means 50. The imaging timing is synchronized with the projection timing of the test pattern from the projector 10a and the projector 10b. Image information of the monitor image captured by the monitor image capturing means 50 is sent to the image processing circuit 52.

  The image processing circuit 52 calculates a predetermined shift (difference) amount based on the image information of the obtained monitor image. This shift (difference) includes a shift between the monitor image projected by the projector 10a and the monitor image projected by the projector 10b, or a predetermined image to be formed as a monitor image and the projector 10a and the projector 10b. Deviations from the projected monitor image are included. In addition to the positional shift on the projection surface, this shift includes a light quantity shift, a focus shift, a magnification shift, and the like.

  Further, the image processing circuit 52 calculates correction information for correcting the above-described deviation, and the position of the linear stage 12 is adjusted based on the calculated correction information. The linear stage 12 can be adjusted in six axes. That is, adjustment in the X-axis direction, adjustment in the Y-axis direction, adjustment in the Z-axis direction, adjustment using the X-axis as the rotation axis, adjustment using the Y-axis as the rotation axis, and adjustment using the Z-axis as the rotation axis Is possible.

  FIG. 11 is a diagram showing an example of the position adjustment described above. For example, as shown in FIG. 11A, it is assumed that the monitor image by the projector 10a and the monitor image by the projector 10b are shifted by ΔX in the X-axis direction and ΔY in the Y-axis direction. In such a case, as shown in FIGS. 11B and 11C, the linear stage 12 is moved in the X-axis direction and the Y-axis direction, so that the positional relationship between the projector 10a and the projector 10b is changed. It is possible to correct appropriately.

  Further, the image processing circuit 52 sends information for correcting the focus shift and magnification shift to the relay optical system 18a and the relay optical system 18b as necessary, and adjustment of the relay optical system 18a and the relay optical system 18b. Is done.

  As described above, the spatial modulation means including the projector 10a, the optical rotation plate 14a, the polarizing plate 16a, and the relay optical system 18a, and the spatial modulation means including the projector 10b, the optical rotation plate 14b, the polarizing plate 16b, and the relay optical system 18b. At least one of the positions relative to the optical path combining means (polarizing beam splitter 22) can be adjusted.

  Although the above-described position adjustment can be performed at a desired time, the position adjustment can be reliably performed every time an image is viewed by the image projection apparatus by performing the adjustment at the time of starting the image projection apparatus.

  As described above, according to the present embodiment, projection light from a plurality of projectors is combined by the polarization beam splitter, and leakage light from the polarization beam splitter is used as a monitor image. By adopting such a configuration, it is possible to easily and accurately adjust the positional relationship of the projection light, and it is possible to obtain an inexpensive image projection apparatus with excellent display quality.

(Embodiment 2)
Next, an image projection apparatus according to a second embodiment of the present invention will be described. Note that the basic configuration of the present embodiment is the same as that of the first embodiment, and differences from the first embodiment will be mainly described below.

  In the first embodiment, as shown in FIG. 5, the optical rotation plate 14b is provided on the exit side of the projector 10b. However, in this embodiment, as shown in FIG. 12, the optical rotation plate 62 is used instead of the optical rotation plate 14b. And the λ / 2 plate 64, and the optical rotation plate 62 and the λ / 2 plate 64 perform the same function as the optical rotation plate 14b.

  The optical rotatory plate 62 is the same as the optical rotatory plate 14a provided on the output side of the projector 10a, and rotates P-polarized G light to convert it to S-polarized light, and rotates S-polarized R light and B light. Without passing through. As a result, S-polarized projection light is emitted from the optical rotation plate 62 for all of R light, G light, and B light. S-polarized light of these R light, G light, and B light is rotated 90 degrees by the λ / 2 plate 64 and converted to P-polarized light.

  Accordingly, as in the first embodiment, S-polarized R light, G light, and B light are transmitted from the projector 10a side, and P-polarized R light, G light, and B light are transmitted from the projector 10b side to the polarization beam splitter. 22 will be supplied.

  Thus, in this embodiment, the same optical rotation plate is used for the optical rotation plate 14a on the projector 10a side and the optical rotation plate 62 on the projector 10b side. Therefore, it is not necessary to manufacture separate optical rotation plates, and the manufacturing cost can be suppressed.

(Embodiment 3)
Next, an image projection apparatus according to a third embodiment of the present invention will be described. Note that the basic configuration of the present embodiment is the same as that of the first embodiment, and differences from the first embodiment will be mainly described below.

  In the first embodiment, as shown in FIG. 2, one image sensor is used as the monitor image capturing unit 50. However, in this embodiment, four image capturing units are used as the monitor image capturing unit as shown in FIG. Elements 50a to 50d are used. A test pattern projected on the four corners of the monitor screen 48 is picked up by these four image pickup devices 50a to 50d.

  Thus, in this embodiment, since the four corners of the monitor screen 48 are imaged by the four imaging elements 50a to 50d, it is possible to acquire the positional information with high accuracy in a wide range.

(Embodiment 4)
Next, an image projection apparatus according to a fourth embodiment of the present invention will be described. Note that the basic configuration of the present embodiment is the same as that of the first embodiment, and differences from the first embodiment will be mainly described below.

  In the present embodiment, as shown in FIG. 14, the polarization rotation as a polarization conversion means is performed between one of the spatial modulation means (projector 10a, optical rotation plate 14a, polarizing plate 16a and relay optical system 18a) and the polarization beam splitter 22. A liquid crystal panel 72a is provided, and a polarization rotation liquid crystal panel 72b is provided as a polarization conversion means between the other spatial modulation means (projector 10b, optical rotation plate 14b, polarizing plate 16b and relay optical system 18b) and the polarization beam splitter 22. ing.

  The functions of the polarization rotation liquid crystal panels 72a and 72b are the same as the functions of the polarization rotation liquid crystal panel 32 described in the first embodiment. That is, the polarization rotation liquid crystal panels 72a and 72b are configured to be able to control the rotation of the polarization by turning on and off the applied voltage. When the voltage applied to the liquid crystal panel is off, the P-polarized light does not rotate but passes through the liquid crystal panel as P-polarized light, and similarly, the S-polarized light does not rotate and passes through the liquid crystal panel as S-polarized light. When the voltage applied to the liquid crystal panel is on, P-polarized light is rotated to S-polarized light, and S-polarized light is rotated to P-polarized light.

  When a normal image is presented to the viewer, the voltage applied to the liquid crystal panels 72a and 72b is turned off. As a result, the S-polarized projection light passes through the liquid crystal panel 72a without turning, and the P-polarized projection light passes through the liquid crystal panel 72b without turning. As a result, as in the first embodiment, most of the S-polarized projection light is reflected by the polarization separation surface 24 of the polarization beam splitter 22 and travels toward the projection optical system 36 side. The portion passes through the polarization separation surface 24 of the polarization beam splitter 22 and travels toward the projection optical system 36 side.

  When the test pattern is projected, the voltage applied to the liquid crystal panels 72a and 72b is turned on. Thereby, the S-polarized projection light is converted into P-polarized light by the liquid crystal panel 72a, and the P-polarized projection light is converted into S-polarized light by the liquid crystal panel 72b. As a result, most of the P-polarized projection light passes through the polarization separation surface 24 of the polarization beam splitter 22 and travels toward the monitor screen 48, and most of the S-polarization projection light is polarized by the polarization beam splitter 22. Reflected by the surface 24 and directed toward the monitor screen 48 side.

  Thus, according to this embodiment, when projecting a test pattern, most of the projection light from the projector 10a and the projector 10b can be projected onto the monitor screen 48. Therefore, the light quantity of the monitor image can be increased, and the imaging accuracy can be improved. Since the projection time of the test pattern is short, even if most of the projection light from the projector is projected on the monitor screen side, the viewer does not feel uncomfortable.

(Embodiment 5)
Next, an image projection apparatus according to a fifth embodiment of the present invention will be described. Note that the basic configuration of the present embodiment is the same as that of the first embodiment, and differences from the first embodiment will be mainly described below.

  In the present embodiment, as shown in FIG. 15, a light amount adjusting unit 82a is provided between one of the spatial modulation units (projector 10a, optical rotator 14a, polarizing plate 16a and relay optical system 18a) and the polarizing beam splitter 22. In addition, a light amount adjusting means 82 b is provided between the other spatial modulation means (projector 10 b, optical rotatory plate 14 b, polarizing plate 16 b and relay optical system 18 b) and the polarizing beam splitter 22.

  FIG. 16 is a diagram illustrating a configuration example of the light amount adjusting unit 82 (pointing to one of the light amount adjusting units 82a and 82b). FIG. 16A is a plan view, and FIG. 16B is a side view.

  The light amount adjusting means 82 is configured by providing a plurality of ND filters 204 in the circumferential direction of the rotating plate 202, and the rotating plate 202 can be rotated by a step motor 208 provided on the rotating shaft 206 of the rotating plate 202. . In this example, the transmittance of each ND filter 204 is 70%, 75%, 80%, 85%, 90%, and 95%, and the desired ND filter 204 can be selected by rotating the rotating plate 202. ing.

  As described above, monitor image information can be acquired by capturing the test pattern projected on the monitor screen 48 with the monitor image capturing means 50. The monitor image information includes information related to the light amount of the monitor image. Therefore, based on the information of the monitor image, the light amount difference between the monitor image projected by the projector 10a and the monitor image projected by the projector 10b, or the predetermined image to be formed as the monitor image and the projector 10a, A light amount difference from the monitor image projected by the projector 10b can be obtained. Based on the information regarding the obtained light amount difference, the optimum ND filter 204 is set in the light amount adjusting unit 82a and the light amount adjusting unit 82b.

  As described above, according to the present embodiment, by providing the light amount adjusting means, the light amount of the projection light emitted from each projector can be adjusted, so that the display quality of the image projection apparatus can be improved.

  Since the monitor image capturing unit 50 captures a monitor image at predetermined time intervals, the light amount can be adjusted based on the temporal change in the light amount of the captured monitor image, so that the display is always optimized. Can do.

  Further, since the monitor image picked up by the monitor image pickup means 50 is formed using the leaked light from the polarization beam splitter 22, the light quantity of the monitor image is changed according to the optical characteristics of the polarization beam splitter 22 (polarization separation surface 24). It is preferable to correct the light amount based on the corrected light amount of the monitor image, and to adjust the light amount based on the corrected light amount of the monitor image.

  In addition, as shown in FIG. 17, since the number of set transmittances can be significantly increased by superimposing a plurality of rotating plates 202 (in this example, 6 × 6 = 36 ways), it is more strict. It is possible to adjust the amount of light.

  Further, instead of the light amount adjusting means 82a and 82b using the ND filter, the polarization swivel liquid crystal panels 72a and 72b shown in FIG. 14 of the fourth embodiment can be used as the light amount adjusting means. By setting the voltage applied to the liquid crystal panels 72a and 72b to a voltage between the on voltage and the off voltage, the turning angle in the liquid crystal panels 72a and 72b can be set between 0 degrees and 90 degrees. Therefore, by adjusting the turning angle, the ratio of P-polarized light and S-polarized light emitted from the liquid crystal panels 72a and 72b can be adjusted, and the light amount can be adjusted.

(Embodiment 6)
Next, an image projection apparatus according to a sixth embodiment of the present invention will be described. Note that the basic configuration of the present embodiment is the same as that of the first embodiment, and differences from the first embodiment will be mainly described below.

  In the first embodiment, as shown in FIG. 8, the pixel position of the projected image is shifted by a ½ pixel pitch in the horizontal direction and the vertical direction, thereby achieving high resolution. In this embodiment, the pixel positions of the projection images from the projector 10a and the projector 10b are made to coincide with each other without shifting the pixel positions of the projection image.

  18A is a pixel arrangement by the projection light of the projector 10a, FIG. 18B is a pixel arrangement by the projection light of the projector 10b, and FIG. 18C is a screen arrangement by the projection light of the projector 10a and the projector 10b. A composite pixel arrangement is shown. As shown in FIG. 18C, the pixel positions of the projection light of the projector 10a and the projector 10b coincide with each other on the screen surface. In FIG. 18C, the pixel positions of the projection light of the projector 10a and the projector 10b are drawn slightly shifted for convenience of explanation, but they are actually coincident.

  As described above, by matching the pixel positions of the projection light of the projector 10a and the projector 10b, it is possible to obtain a high-luminance image or a three-dimensional image (3D image). That is, by projecting the same image from the projector 10a and the projector 10b, the brightness of the projection light can be increased. A three-dimensional image can be obtained by projecting a right-eye image from the projector 10a and projecting a left-eye image from the projector 10b.

(Embodiment 7)
Next, an image projection apparatus according to a seventh embodiment of the present invention will be described. Note that the basic configuration of the present embodiment is the same as that of the first embodiment, and differences from the first embodiment will be mainly described below.

  This embodiment relates to multi-primary color display. That is, in this embodiment, by using six primary colors (R1, R2, G1, G2, B1, B2) having the characteristics shown in FIG. 20, the color reproduction range is expanded as shown in FIG. Yes.

  FIG. 21 is a diagram schematically illustrating a configuration example of the spatial modulation unit in the present embodiment. In the present embodiment, as shown in FIG. 21, a red (R) color filter 120R is provided between the polarizing beam splitter 112R and the dichroic prism 118, and a green (G) is provided between the polarizing beam splitter 112G and the dichroic prism 118. The blue (B) color filter 120B is disposed between the polarization beam splitter 112B and the dichroic prism 118.

  In the projector 10a, the color filter having the characteristics of R1 shown in FIG. 20 as the color filter 120R, the color filter having the characteristics of G1 shown in FIG. 20 as the color filter 120G, and B1 shown in FIG. 20 as the color filter 120B. The color filters having the above characteristics are arranged respectively.

  In the projector 10b, a color filter having the R2 characteristic shown in FIG. 20 as the color filter 120R, a color filter having the G2 characteristic shown in FIG. 20 as the color filter 120G, and B2 shown in FIG. 20 as the color filter 120B. The color filters having the above characteristics are arranged respectively.

  The pixel positions of the projection light of the projector 10a and the projector 10b are made to coincide with each other in the same manner as shown in FIG. 18 of the sixth embodiment.

  By adopting the configuration as described above, it is possible to obtain a high-performance image projection apparatus having a color reproduction range as shown in FIG. Note that multi-primary colors may be achieved by using a dichroic mirror or the like instead of the color filter.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining the disclosed constituent elements. For example, even if several constituent requirements are deleted from the disclosed constituent requirements, the invention can be extracted as an invention as long as a predetermined effect is obtained.

It is the figure shown about the use condition of the image projector which concerns on the 1st Embodiment of this invention. It is the figure which showed typically the whole structure of the image projector which concerns on the 1st Embodiment of this invention. It is the figure which showed typically the whole structure of the image projector which concerns on the 1st Embodiment of this invention. FIG. 4 is a diagram schematically illustrating a configuration example of a spatial modulation unit according to the first embodiment of the present invention. It is a figure for demonstrating functions of an optical rotation board etc. concerning the 1st Embodiment of this invention. FIG. 4 is a diagram illustrating a principle of a light beam shift unit according to the first embodiment of the present invention. FIG. 6 is a diagram illustrating pixel shift by a light beam shift unit according to the first embodiment of the present invention. FIG. 6 is a diagram illustrating a pixel arrangement state of projection light according to the first embodiment of the present invention. FIG. 4 is a diagram illustrating an example of a test pattern imaged on a monitor screen according to the first embodiment of the present invention. FIG. 6 is a diagram illustrating a projection timing of a test pattern from a projector according to the first embodiment of the present invention. FIG. 6 is a diagram illustrating an example of position adjustment according to the first embodiment of the present invention. It is a figure for demonstrating functions of an optical rotation board etc. concerning the 2nd Embodiment of this invention. It is the figure which showed typically the whole structure of the image projector which concerns on the 3rd Embodiment of this invention. It is the figure which showed typically the whole structure of the image projector which concerns on the 4th Embodiment of this invention. It is the figure which showed typically the whole structure of the image projector which concerns on the 5th Embodiment of this invention. It is a figure showing an example of composition of a light quantity adjustment means concerning a 5th embodiment of the present invention. FIG. 16 is a diagram illustrating another example of the configuration of the light amount adjusting unit according to the fifth embodiment of the present invention. FIG. 16 is a diagram illustrating superimposition of projection light according to the sixth embodiment of the present invention. FIG. 20 is a diagram illustrating a color reproduction range according to the seventh embodiment of the present invention. FIG. 20 is a diagram illustrating characteristics of a color filter according to a seventh embodiment of the present invention. FIG. 20 is a diagram schematically illustrating a configuration example of a spatial modulation unit according to the seventh embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image projector 2 ... Screen 10, 10a, 10b ... Projector 12 ... Linear stage 14, 14a, 14b ... Optical rotation plate 16, 16a, 16b ... Polarizing plate 18, 18a, 18b ... Relay optical system 20 ... Reflection mirror 22 ... Polarization beam splitter 24 ... Polarization separation surface 30 ... Light beam shifting means 32 ... Polarization rotating liquid crystal panel 34 ... Birefringence plate 36 ... Projection optical system 42 ... Optical aperture 44 ... Reflection mirror 46 ... Monitoring optical system 48 ... Monitor screen 50 ... Monitor image capturing means 52... Image processing circuit 54... Image reproducing section 62... Rotating plate 64... Λ / 2 plate 72 a, 72 b ... Polarization turning liquid crystal panel 82, 82 a, 82 b. 110 ... Dichroic mirror 108 ... Reflection mirror 112R, 112G, 112B ... Polarized light Beam splitter 114R, 114G, 114B: Polarization separation surface 116R, 116G, 116B: Reflective LCD
118 ... Dichroic prism 120R, 120G, 120B ... Color filter 202 ... Rotating plate 204 ... ND filter 206 ... Rotating shaft 208 ... Step motor

Claims (30)

An image projection apparatus for projecting an image based on an input video signal onto a screen,
A light source that emits illumination light;
First and second spatial modulation means for modulating the illumination light based on an input video signal to generate projection light that is linearly polarized light;
Optical path synthesis means for synthesizing the projection lights generated by the first and second spatial modulation means using the property that their polarization directions are orthogonal to each other;
An optical path separating means for separating a part of the projected light when the projected light is combined by the optical path combining means;
Projection optical means for projecting the projection light synthesized by the optical path synthesis means on a screen;
Monitor image capturing means for capturing the projection light separated by the optical path separating means as a monitor image;
An image projection apparatus comprising: The apparatus further comprises position adjusting means for adjusting the position of at least one of the first and second spatial modulation means relative to the optical path combining means based on the monitor image picked up by the monitor image pick-up means. The image projection apparatus according to claim 1. The apparatus further comprises difference detection means for detecting a difference between the image generated by the first spatial modulation means and the image generated by the second spatial modulation means from the monitor image captured by the monitor image imaging means. The image projection apparatus according to claim 1, wherein The apparatus further comprises difference detection means for detecting a difference between a predetermined image to be formed as a monitor image based on the video signal and the monitor image picked up by the monitor image pick-up means. The image projection apparatus described in 1. The apparatus further comprises position adjusting means for adjusting a position of at least one of the first and second spatial modulation means with respect to the optical path combining means based on the difference detected by the difference detecting means. 5. The image projection apparatus according to 3 or 4. The image projection apparatus according to claim 5, wherein a video signal input when the position adjustment unit performs position adjustment is a video signal of a test pattern for detecting the difference. The image projection apparatus according to claim 6, wherein the position adjustment by the position adjustment unit is performed when the image projection apparatus is activated. The image projection apparatus according to claim 6, wherein the video signal of the test pattern is input to the first spatial modulation unit and the second spatial modulation unit in a time division manner. The test pattern video signal input to the first spatial modulation means and the test pattern video signal input to the second spatial modulation means are set to have different test pattern shapes. The image projection apparatus according to claim 6. The test pattern video signal input to the first spatial modulation means and the test pattern video signal input to the second spatial modulation means are set to have different test pattern colors. The image projection apparatus according to claim 6. The test pattern video signal input to the first and second spatial modulation means is a green test pattern video signal,
The position adjusting means adjusts the position of at least one of the first and second spatial modulation means relative to the optical path combining means based on a monitor image of the green test pattern. The image projection apparatus described in 1. The image projection apparatus according to claim 6, wherein the video signal of the test pattern is input during a predetermined period in which the video signal of the video to be presented to the viewer is not input. The image projection apparatus according to claim 12, wherein the predetermined period is a horizontal blanking period or a vertical blanking period of a video signal of a video to be presented to the viewer. The difference detected by the difference detection means is a light amount difference,
Based on the light quantity difference, the light quantity of the projection light generated by at least one of the first and second spatial modulation means between at least one of the first and second spatial modulation means and the optical path separation means. The image projection apparatus according to claim 3, further comprising a light amount adjusting unit that adjusts the light amount. The image projection apparatus according to claim 14, wherein the light amount adjusting unit performs light amount adjustment based on a temporal light amount change of the monitor image captured by the monitor image capturing unit. The image projection apparatus according to claim 14, wherein the light amount adjusting unit performs light amount adjustment based on a light amount of the monitor image corrected based on an optical characteristic of the optical path separating unit. The image projection apparatus according to claim 14, wherein the light amount adjustment unit includes an ND filter for light amount adjustment. Each of the first and second spatial modulation means has at least one spatial modulation element,
The image projection apparatus according to claim 1, wherein the monitor image capturing unit captures a monitor image formed on a plane conjugate with a display surface of the spatial modulation element. Each of the first and second spatial modulation means has a plurality of spatial modulation elements corresponding to a plurality of colors,
One of the first and second spatial modulation means has an optical rotation plate that rotates the polarization direction of the projection light from the spatial modulation element corresponding to a predetermined color,
The other of said 1st and 2nd spatial modulation means has an optical rotation board which turns the polarization direction of the projection light from the spatial modulation element corresponding to colors other than the said predetermined color. The image projection apparatus described. Each of the first and second spatial modulation means includes a plurality of spatial modulation elements corresponding to a plurality of colors, and an optical rotation plate that rotates the polarization direction of projection light from the spatial modulation elements corresponding to a predetermined color. And
2. The image projection apparatus according to claim 1, wherein one of the first and second spatial modulation units further includes a λ / 2 plate that rotates a polarization direction of projection light from the optical rotation plate. From the first spatial modulation means and the second spatial modulation means, respectively, between the first spatial modulation means and the optical path synthesis means and between the second spatial modulation means and the optical path synthesis means, respectively. The image projection apparatus according to claim 1, further comprising polarization conversion means capable of rotating a polarization direction of the projection light. The image projection apparatus according to claim 21, wherein the polarization conversion unit rotates the polarization direction of the projection light by 90 degrees when a video signal of a test pattern is input. The optical path combining means is composed of a polarization beam splitter,
Each of the first and second spatial modulation means includes at least one spatial modulation element and a relay optical system that guides the projection light modulated by the at least one spatial modulation element to the polarization beam splitter. The image projection apparatus according to claim 1. The optical path combining means is composed of a polarization beam splitter,
The projection light generated by one of the first and second spatial modulation means is S-polarized light, and the projection light generated by the other of the first and second spatial modulation means is P-polarized light,
The projection optical unit projects the S-polarized projection light reflected by the polarization separation surface of the polarization beam splitter and the P-polarization projection light transmitted through the polarization separation surface of the polarization beam splitter onto the screen. The image projection apparatus according to claim 1. The optical path separating means is composed of the polarization beam splitter,
The monitor image imaging means uses the S-polarized leakage light transmitted through the polarization separation surface of the polarization beam splitter and the P-polarized leakage light reflected by the polarization separation surface of the polarization beam splitter as the monitor image. The image projection apparatus according to claim 24, wherein an image is picked up. The image projection apparatus according to claim 1, wherein the monitor image capturing unit captures four corners of the monitor image. The monitor image capturing means has four image sensors,
27. The image projection apparatus according to claim 26, wherein the four corners of the monitor image are respectively captured by the four imaging elements. The monitor image capturing means has one image sensor,
The image projection device according to claim 26, wherein the four corners of the monitor image are simultaneously imaged by the one image sensor. Between the optical path synthesizing unit and the projection optical unit, two states of shifting or not shifting the light beam of the projection light directed to the screen in synchronization with the modulation timing of the first and second spatial modulation units The image projection apparatus according to claim 1, further comprising: a light beam shifting unit that switches between the two. The light beam shift means includes a liquid crystal panel capable of rotating the polarization direction of the projection light, and a birefringent plate that generates transmitted light deviated from the extension line of the incident light when the incident light is polarized in a specific direction. And
30. The image projection apparatus according to claim 29, wherein the liquid crystal panel rotates the polarization direction of the projection light in synchronization with the modulation timing of the first and second spatial modulation means.

Images