JP2010217652A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector for effectively suppressing color irregularity even when the incident angle depends on the incident position of illumination light to a dichroic mirror. <P>SOLUTION: A color separation light-guide optical system 30 has a first correction dichroic mirror 38r for offsetting the incident angle dependence on the luminous flux of R color as the first color branched by a first separation dichroic mirror 31a. Therefore, even when the incident angle of the R color light to the first separation dichroic mirror 31a depends on the incident position, inhomogeneous distribution of the illumination light of the R color is avoided and a light bulb 40r can be illuminated uniformly. Therefore, occurrence of color irregularity in a projected image about the R color can be suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a projector that separates illumination light obtained from a single light source, illuminates a plurality of color light valves, and synthesizes and projects modulated light from each color light valve.

  In a projector, a dichroic mirror is used for color separation of illumination light. However, the dichroic mirror has a wavelength shift in color separation characteristics due to transmission and reflection depending on the incident angle of the light beam. For this reason, when there is a difference in the incident angle of the illumination light in a local region corresponding to the left and right of the screen among the dichroic mirrors, color unevenness and brightness unevenness may occur on the projection screen, and the image quality may deteriorate.

In order to solve the problems such as luminance unevenness caused by the dichroic mirror as described above, for example, an angle formed by the normal line of the dichroic mirror and the optical axis is set to 45 ° or less (see Patent Document 1). As described above, when the inclination of the dichroic mirror is reduced, the wavelength shift amount of the color separation characteristic depending on the incident angle to the dichroic mirror is reduced, and the color unevenness of the projected image is reduced to some extent.
Further, since the wavelength (edge wavelength), which is the cutoff frequency in the region where the transmittance characteristic or reflectance characteristic of the dichroic mirror is largely switched, differs between the P-polarized light and the S-polarized light, the reflectance characteristic or transmittance of the dichroic mirror is different. It is disclosed that the characteristics depend on the incident angle of light (Patent Document 2).

Japanese Patent Laid-Open No. 5-66308 Japanese Patent No. 3944648

  However, as described in Patent Document 1, even if the inclination of the dichroic mirror is reduced, the wavelength shift corresponding to the difference in the incident angle of the illumination light remains, so that the required level for reducing the uneven color of the projected image is increased. It was not easy to meet.

  Therefore, an object of the present invention is to provide a projector capable of effectively suppressing color unevenness even when there is a difference in incident angle depending on the incident position of illumination light on a dichroic mirror.

  In order to solve the above problems, a projector according to the present invention separates a first color light beam by a first separation dichroic mirror from a lighting device that emits a light beam and a light beam emitted from the lighting device, A color separation light guide optical system that separates the light beam that has passed through the separation dichroic mirror into a second color light beam and a third color light beam by the second separation dichroic mirror, and a first color emitted from the color separation light guide optical system , A light modulator having a first light valve, a second light valve, and a third light valve that modulate light beams of the second color and the third color, respectively, according to image information, a first light valve, and a second light valve. A light combining optical system that combines the modulated light of the first color, the second color, and the third color emitted from the light valve and the third light valve, respectively, and the image light combined through the light combining optical system A color separation light guide optical system for the first color that cancels the incident angle dependency of the light beam of the first color separated from the light beam of the second color by the first separation dichroic mirror. It has a correction dichroic mirror.

  In the projector described above, the color separation light guide optical system includes the correction dichroic mirror for the first color that cancels the incident angle dependency of the light beam of the first color branched by the first separation dichroic mirror. Even if the incident angle of the light beam on the first separation dichroic mirror varies depending on the incident position, it is possible to suppress the occurrence of uneven color in the projected image due to the uneven distribution of the illumination light of the first color. .

  According to a specific aspect of the invention, in the projector, the first color light beam is separated from the second color light beam and the third color light beam by the reflection of the first separation dichroic mirror, and the first color The correction dichroic mirror is arranged so as to extend perpendicularly to the reflecting surface from a normal extending along the reflecting surface provided on the branched first color optical path and perpendicular to the reference surface including the system optical axis. Is done. The reflection surface includes a first separation dichroic mirror and an incident surface arranged downstream of the optical path. In this case, the light beam of the first color to be separated by the first separation dichroic mirror can be uniformly guided to the correction dichroic mirror, and as the incident angle of the illumination light to the first separation dichroic mirror increases, The incident angle to the correction dichroic mirror becomes smaller, and the correction dichroic mirror enables a filtering process to achieve appropriate compensation.

  According to another aspect of the present invention, the edge wavelength of the wavelength region where the reflection characteristic of the first separation dichroic mirror is switched moves to the second color side as the incident angle increases, and the correction color dichroic mirror for the first color moves. The edge wavelength of the wavelength region of the wavelength region where the transmission characteristics are switched moves to the second color side as the incident angle increases. In this case, the illumination light whose relative light reduction amount at the first separation dichroic mirror is large has a small relative light reduction amount at the correction dichroic mirror for the first color, and is relative to the first separation dichroic mirror. Illumination light having a small amount of light reduction increases the relative light reduction amount at the correction dichroic mirror for the first color, and reduces the influence of the incident position of the illumination light on the first separation dichroic mirror in a complementary manner. be able to.

  According to still another aspect of the present invention, the color separation light guide optical system includes a correction dichroic mirror for the second color that cancels the incident angle dependency of the light beam of the second color. In this case, even if the incident angle of the light beam of the second color on the first separation dichroic mirror varies depending on the incident position, color unevenness occurs in the projected image due to the non-uniform distribution of the illumination light of the second color. This can be suppressed.

  According to still another aspect of the present invention, the second color light beam is separated from the first color light beam by transmission through the first separation dichroic mirror, and the second color correction dichroic mirror is branched. It is arranged so as to extend perpendicularly to the reflecting surface from a normal line extending along the reflecting surface provided on the optical path of the second color and extending perpendicularly to the reference surface including the system optical axis. The reflection surface includes the second separation dichroic mirror and an incident surface disposed downstream of the optical path. In this case, the light beam of the second color after being separated by the first separation dichroic mirror can be uniformly guided to the correction dichroic mirror, and the incident angle of the illumination light to the first separation dichroic mirror or the second separation dichroic mirror is large. As the incident angle to the correction dichroic mirror for the second color becomes smaller, the correction processing for achieving appropriate compensation by the correction dichroic mirror for the second color becomes possible.

  According to still another aspect of the present invention, the edge wavelength in the wavelength region where the transmission characteristic of the first separation dichroic mirror or the reflection characteristic of the second separation dichroic mirror is switched moves to the second color side as the incident angle increases. The edge wavelength in the wavelength region where the transmission characteristics of the correction dichroic mirror for the second color are switched moves to the second color side as the incident angle increases. In this case, the illumination light having a large relative light reduction amount at the first and second separation dichroic mirrors has a small relative light reduction amount at the correction dichroic mirror for the second color, and the first and second separation light beams are reduced. The illumination light whose relative light reduction amount at the dichroic mirror is small increases the relative light reduction amount at the correction dichroic mirror for the second color, and the incident light incident position on the first separation dichroic mirror or the like The influence can be reduced in a complementary manner.

  According to still another aspect of the present invention, the color separation / light guiding optical system cancels the incident angle dependency of the third color light beam separated from the second color light beam by the second separation dichroic mirror. A correction dichroic mirror. In this case, even if the incident angle of the light beam of the third color on the first separation dichroic mirror varies depending on the incident position, color unevenness occurs in the projected image due to the non-uniform distribution of the illumination light of the third color. This can be suppressed.

  According to still another aspect of the present invention, the third color light beam is separated from the second color light beam by transmission through the second separation dichroic mirror, and the third color correction dichroic mirror is On the optical paths of the three colors, they are arranged so as to be parallel to a normal extending perpendicular to the reference plane including the system optical axis and perpendicular to the second separation dichroic mirror. In this case, the third color light beam branched by the second separation dichroic mirror can be uniformly guided to the correction dichroic mirror, and the larger the incident angle of the illumination light to the second separation dichroic mirror, The incident angle to the correction dichroic mirror is reduced, and the third chromatic correction dichroic mirror enables filter processing to achieve appropriate compensation.

  According to still another aspect of the present invention, the edge wavelength of the wavelength region where the transmission characteristics of the second separation dichroic mirror are switched moves to the third color side as the incident angle increases, and the corrected dichroic mirror for the third color. The edge wavelength in the wavelength region where the transmission characteristics of the color shifts moves to the third color side as the incident angle increases. In this case, the illumination light having a large relative light reduction amount at the second separation dichroic mirror has a smaller relative light reduction amount at the correction dichroic mirror for the third color, and the relative light amount at the second separation dichroic mirror is relatively small. The illumination light having a small amount of light reduction increases the relative light reduction amount at the correction dichroic mirror for the third color, and complementarily reduces the influence of the incident position of the illumination light on the second separation dichroic mirror. be able to.

It is a top view explaining the optical system of the projector of this embodiment. It is a graph which illustrates the transmission wavelength characteristic of the 1st separation dichroic mirror and the 1st amendment dichroic mirror. 6 is a graph illustrating reflection / transmission wavelength characteristics of a first separation dichroic mirror and a first correction dichroic mirror. It is a graph which shows the synthesized wavelength characteristic. It is a graph which illustrates the transmission wavelength characteristic of a 1st isolation | separation dichroic mirror and a 2nd correction | amendment dichroic mirror. It is a graph which shows the synthesized wavelength characteristic. It is a graph which illustrates the transmission wavelength characteristic of a 2nd isolation | separation dichroic mirror and a 2nd correction | amendment dichroic mirror. It is a graph which shows the synthesized wavelength characteristic. It is a graph which illustrates the transmission wavelength characteristic of the 2nd separation dichroic mirror and the 3rd amendment dichroic mirror. It is a graph which shows the synthesized wavelength characteristic.

  FIG. 1 is a conceptual diagram illustrating the structure of an optical system of a projector according to an embodiment of the invention.

  The projector 100 is an optical device for modulating illumination light obtained from a light source in accordance with image information to form an optical image and enlarging and projecting the optical image on a screen. The projector 100 includes a light source device 10, a uniformizing optical system 20, a color separation / light guiding optical system 30, a light modulation unit 40, a cross dichroic prism 50, and a projection lens 60. Here, the light source device 10 and the homogenizing optical system 20 constitute an illumination device. The light modulator 40 includes three light valves 40r (for R color light), 40g (for G color light), and 40b (for B color light). Each of the light valves 40r, 40g, and 40b is a liquid crystal display device that displays an image by modulating different color lights.

  In the projector 100, the light source device 10 includes a discharge light-emitting arc tube 11 that is an example of a light source lamp, and a main condensing reflector 12. Here, the arc tube 11 is specifically an ultra-high pressure mercury lamp which is a kind of mercury lamp, and emits light by causing arc discharge in mercury vapor containing a rare gas. The reflector 12 is, for example, a parabolic mirror, and emits a substantially collimated light beam by reflecting light emitted from the arc tube 11. The reflector 12 may be an ellipsoidal mirror, for example. In this case, if a concave lens or the like is disposed on the exit side of the reflector 12, the emitted light from the reflector 12 can be collimated.

  The homogenizing optical system 20 supplies the illumination light with uniform illuminance to the light modulation unit 40 via the color separation light guiding optical system 30. The homogenizing optical system 20 superimposes the first and second lens arrays 23 and 24 that divide the light beam emitted from the light source device 10 into an appropriate state and a plurality of light beams that have passed through both lens arrays 23 and 24. A lens 25 and a polarization conversion device 27 that aligns the polarization direction of the light beam incident on the superimposing lens 25 are provided. The first and second lens arrays 23 and 24 are each composed of a plurality of element lenses 23a and 24a arranged in a matrix. Among these, the light beam from the reflector 12 is divided into a plurality of partial light beams by the element lens 23 a constituting the first lens array 23. Further, the partial lenses 24a constituting the second lens array 24 emit the partial light beams from the first lens array 23 at an appropriate divergence angle. The superimposing lens 25 appropriately converges the partial light beam emitted from the second lens array 24 and having passed through the polarization conversion device 27 as a whole, and superimposes it on the illuminated area, that is, the display area of the downstream light valves 40r, 40g, and 40b. Although not described in detail, the polarization conversion device 27 includes a prism array in which a PBS and a mirror are incorporated, and a wave plate array that is attached in a stripe shape on an exit surface provided in the prism array. The polarization conversion device 27 has a role of making the polarization direction of each partial light beam divided by the first lens array 23 and passing through the second lens array 24 into one direction to be linearly polarized light.

  The color separation light guide optical system 30 includes two separation dichroic mirrors 31a and 31b, three correction dichroic mirrors 38r (for R color light), 38g (for G color light), 38b (for B color light), and three reflection mirrors. 32a, 32b, and 32c, and three field lenses 33r (for R color light), 33g (for G color light), and 33b (for B color light). The color separation light guide optical system 30 separates the illumination light emitted from the uniformizing optical system 20 into three colors of R color, G color, and B color, and separates each color light into downstream light valves 40r, 40g, and 40b. Lead to. More specifically, first, the first separation dichroic mirror 31a reflects R color light and transmits G color light and B color light among the three colors of RGB. The second separation dichroic mirror 31b reflects the G color light and transmits the B color light among the two colors of GB. In the color separation light guide optical system 30, the R color light reflected by the first separation dichroic mirror 31a is reflected by the first reflection mirror 32a and enters the field lens 33r for adjusting the incident angle. Further, the G color light that has been transmitted through the first separation dichroic mirror 31a and reflected by the second separation dichroic mirror 31b is incident on the field lens 33g for adjusting the incident angle. Further, the B-color light that has passed through the second separation dichroic mirror 31b is reflected by the relay lenses LL1 and LL2 and the second and third reflection mirrors 32b and 32c, respectively, and enters the field lens 33b for adjusting the incident angle.

In the first optical path OP1 for R color light, the first reflection mirror 32a is accompanied by a first correction dichroic mirror 38r for R color light, and the R color light reflected at each position of the first reflection mirror 32a is: It passes through the first correction dichroic mirror 38r once. The first correction dichroic mirror 38r has a role of canceling the incident angle dependency of the R color light branched by the first separation dichroic mirror 31a.
In the second optical path OP2 for G color light, the second separation dichroic mirror 31b is accompanied by a second correction dichroic mirror 38g for G color light, and the G color light reflected at each position of the second separation dichroic mirror 31b. Passes once through the second correction dichroic mirror 38g. The second correction dichroic mirror 38g has a role of canceling the incident angle dependency of the G color light branched by the second separation dichroic mirror 31b or the like.
In the third optical path OP3 for B-color light, a third correction dichroic mirror 38b for B-color light is attached to the next stage of the second separation dichroic mirror 31b, and passes through each position of the second separation dichroic mirror 31b. The B color light passes through the third correction dichroic mirror 38b once. The third correction dichroic mirror 38b has a role of canceling the incident angle dependency of the B color light branched by the second separation dichroic mirror 31b.

  The first correction dichroic mirror 38r is disposed so as to extend perpendicularly to the first reflection mirror 32a from the normal line N1 extending in the X direction along the first reflection mirror 32a provided on the first optical path OP1 for R color light. . Here, the normal line N1 intersects the system optical axis SA passing through the center of the first reflecting mirror 32a, and extends perpendicular to the reference plane (YZ plane) including the system optical axis SA. The first correction dichroic mirror 38r extends from the normal line N1 in a 45 ° azimuth between the −Y direction and the + Z direction, and is disposed perpendicular to the YZ plane. Focusing on the R color light incident on the left side toward the first separation dichroic mirror 31a, this R color light is incident on the first separation dichroic mirror 31a at an incident angle E (+) = 45 ° + α, and the first reflection mirror 32a. Then, the light enters the first correction dichroic mirror 38r at an incident angle E (−) = 45 ° −α and passes through it. On the other hand, when attention is paid to the R color light incident on the right side toward the first separation dichroic mirror 31a, the R color light is incident on the first separation dichroic mirror 31a at an incident angle F (−) = 45 ° −α. The light enters the correction dichroic mirror 38r at an incident angle F (+) = 45 ° + α and passes therethrough. In summary, when the light passes through the first separation dichroic mirror 31a and the first correction dichroic mirror 38r, the incident angle of the R color light is reversed with 45 ° therebetween.

  FIG. 2 is a graph for explaining the wavelength characteristic of the transmittance of the first separation dichroic mirror 31a and the wavelength characteristic of the transmittance of the first correction dichroic mirror 38r. In the graph, the solid line indicates the transmission characteristics of R-color light or the like incident on the first separation dichroic mirror 31a at a relatively large incident angle of 50 °, and the broken line indicates the first separation dichroic mirror 31a at a relatively small incident angle of 40 °. The transmission characteristic of incident R color light or the like is shown. In the graph, the alternate long and short dash line indicates transmission characteristics of R-color light and the like incident on the first correction dichroic mirror 38r at a relatively large incident angle of 50 °, and the dotted line indicates a relatively small incident angle on the first correction dichroic mirror 38r. Transmission characteristics of R color light incident at 40 ° are shown.

  FIG. 3 is a graph for explaining the wavelength characteristic of the reflectance of the first separation dichroic mirror 31a and the wavelength characteristic of the transmittance of the first correction dichroic mirror 38r. In the graph, a solid line, a broken line, an alternate long and short dash line, and a dotted line are the same as those in FIG. However, the solid line and the broken line indicate not the transmittance but the reflectance, and the characteristics in FIG. 2 are inverted up and down. As apparent from the graph of FIG. 3, the edge wavelength of the wavelength region where the reflection characteristic of the first separation dichroic mirror 31a is switched moves to the G-color side of the shorter wavelength as the incident angle increases, and the first correction dichroic mirror 38r. The edge wavelength in the wavelength region where the transmission characteristics of the light source shift is shifted to the G-color side with a shorter wavelength as the incident angle increases.

  FIG. 4 is a graph showing wavelength characteristics obtained by combining the reflection at the first separation dichroic mirror 31a and the transmission through the first correction dichroic mirror 38r. The solid line in the graph indicates the wavelength distribution characteristics of the R color light that is incident on the first separation dichroic mirror 31a at a relatively large incident angle of 50 ° and is incident on the first correction dichroic mirror 38r at a relatively small incident angle of 40 °. 1 corresponds to the R color light incident on the left side toward the first separation dichroic mirror 31a. In addition, the broken line in the graph indicates the wavelength distribution characteristic of the R color light that is incident on the first separation dichroic mirror 31a at a relatively small incident angle of 40 ° and is incident on the first correction dichroic mirror 38r at a relatively large incident angle of 50 °. This corresponds to R-color light incident on the right side toward the first separation dichroic mirror 31a in FIG. As is apparent from the graph, the wavelength distribution of the R color light incident on the left side toward the first separation dichroic mirror 31a and reaching the light valve 40r, and the light valve incident on the right side toward the first separation dichroic mirror 31a. The wavelength distribution of the R color light reaching 40r is almost the same, and appropriate filter processing is achieved by the first correction dichroic mirror 38r, and the unevenness of the illuminance distribution of the R color light is reduced to suppress the uneven color of the projected image. be able to.

  Returning to FIG. 1, the second correction dichroic mirror 38g is moved from the normal N2 extending in the X direction along the second separation dichroic mirror 31b provided on the second optical path OP2 for G color light to the second separation dichroic mirror 31b. It is arranged so as to extend vertically. Here, the normal line N2 intersects the system optical axis SA passing through the center of the second separation dichroic mirror 31b, and extends perpendicular to the reference plane (YZ plane) including the system optical axis SA. The second correction dichroic mirror 38g extends from the normal line N2 in a 45 ° azimuth between the + Y direction and the −Z direction, and is disposed perpendicular to the YZ plane. When attention is paid to the long wavelength side of the G color light incident on the left side toward the first separation dichroic mirror 31a, the long wavelength side of the G color light is incident on the first separation dichroic mirror 31a at an incident angle E (+) = 45 ° + α. Incident light passes through the second separation dichroic mirror 31b, enters the second correction dichroic mirror 38g at an incident angle E (−) = 45 ° −α, and passes therethrough. On the other hand, when attention is paid to the long wavelength side of the G color light incident on the right side toward the first separation dichroic mirror 31a, the long wavelength side of the G color light is incident on the first separation dichroic mirror 31a at an incident angle F (−) = 45 °. The light enters at −α, enters the second correction dichroic mirror 38g at an incident angle F (+) = 45 ° + α, and passes through this. In summary, when passing through the first separation dichroic mirror 31a and the second correction dichroic mirror 38g, the incident angle on the long wavelength side of the G color light is reversed across 45 °.

  FIG. 5 is a graph for explaining the wavelength characteristic of the transmittance of the first separation dichroic mirror 31a and the wavelength characteristic of the transmittance of the second correction dichroic mirror 38g. In the graph, the solid line indicates the transmission characteristics of G-color light or the like incident on the first separation dichroic mirror 31a at a relatively large incident angle of 50 °, and the broken line indicates the first separation dichroic mirror 31a at a relatively small incident angle of 40 °. The transmission characteristic of incident G color light or the like is shown. In the graph, the alternate long and short dash line indicates transmission characteristics of G-color light or the like incident on the second correction dichroic mirror 38g at a relatively large incident angle of 50 °, and the dotted line indicates a relatively small incident angle on the second correction dichroic mirror 38g. The transmission characteristics of G color light and the like incident at 40 ° are shown. As is apparent from the graph of FIG. 5, the edge wavelength of the wavelength region where the reflection characteristic of the first separation dichroic mirror 31a is switched moves to the short wavelength side of the G color as the incident angle increases, and the second correction dichroic mirror 38g. The edge wavelength of the wavelength region in which the transmission characteristics of the color shift is shifted to the short wavelength side of G color as the incident angle increases.

  FIG. 6 is a graph showing a wavelength characteristic obtained by synthesizing the transmission of the first separation dichroic mirror 31a and the transmission of the second correction dichroic mirror 38g. The solid line in the graph indicates the wavelength on the long wavelength side of the G color light that is incident on the first separation dichroic mirror 31a at a relatively large incident angle of 50 ° and is incident on the second correction dichroic mirror 38g at a relatively small incident angle of 40 °. 1 shows distribution characteristics and corresponds to G-color light or the like incident on the left side toward the first separation dichroic mirror 31a in FIG. In addition, the broken line in the graph indicates the long wavelength side of the G color light that is incident on the first separation dichroic mirror 31a at a relatively small incident angle of 40 ° and is incident on the second correction dichroic mirror 38r at a relatively large incident angle of 50 °. 1 corresponds to G-color light or the like incident on the right side toward the first separation dichroic mirror 31a in FIG. As is apparent from the graph, the wavelength distribution on the long wavelength side of the G color light incident on the left side toward the first separation dichroic mirror 31a and reaching the light valve 40g, and the right side incident on the first separation dichroic mirror 31a Thus, the wavelength distribution on the long wavelength side of the G color light reaching the light valve 40g substantially matches, and appropriate filtering is achieved by the second correction dichroic mirror 38g, and the illuminance distribution on the long wavelength side of the G color light is not good. Uniformity can be reduced and uneven color in the projected image can be suppressed.

  The above is a description of the compensation on the long wavelength side of the G color light, but the compensation on the short wavelength side of the G color light is also possible by changing the characteristics of the second correction dichroic mirror 38g.

  FIG. 7 is a graph for explaining a modification of the wavelength characteristic of the transmittance of the second separation dichroic mirror 31b and the wavelength characteristic of the transmittance of the second correction dichroic mirror 38g. In the graph, the solid line indicates the transmission characteristics of G-color light or the like incident on the second separation dichroic mirror 31b at a relatively large incident angle of 50 °, and the broken line indicates the second separation dichroic mirror 31b at a relatively small incident angle of 40 °. The transmission characteristic of incident G color light or the like is shown. In the graph, the alternate long and short dash line indicates transmission characteristics of G-color light or the like incident on the second correction dichroic mirror 38g at a relatively large incident angle of 50 °, and the dotted line indicates a relatively small incident angle on the second correction dichroic mirror 38g. The transmission characteristics of G color light and the like incident at 40 ° are shown. As is apparent from the graph of FIG. 7, the edge wavelength of the wavelength region where the transmission characteristic, that is, the reflection characteristic of the second separation dichroic mirror 31b is switched moves to the short wavelength side of the G color as the incident angle increases, and the second correction is performed. The edge wavelength in the wavelength region where the transmission characteristic of the dichroic mirror 38g is switched moves to the short wavelength side of G color as the incident angle increases.

  FIG. 8 is a graph showing the wavelength characteristics obtained by combining the reflection at the second separation dichroic mirror 31b and the transmission through the second correction dichroic mirror 38g. The solid line in the graph is a short G-color light incident on the second separation dichroic mirror 31a at a relatively large incident angle of 50 ° and reflected, and incident on the second correction dichroic mirror 38g at a relatively small incident angle of 40 °. The wavelength distribution characteristic on the wavelength side is shown, and corresponds to G color light or the like incident on the left side toward the second separation dichroic mirror 31b in FIG. Further, the broken line in the graph is incident on the second correction dichroic mirror 38g with a relatively large incident angle of 50 ° and passes therethrough, and is incident on the second separation dichroic mirror 31b with a relatively small incident angle of 40 ° and is reflected. 1 shows the wavelength distribution characteristic of the G color light on the short wavelength side, and corresponds to the G color light incident on the right side toward the second separation dichroic mirror 31b in FIG. As is apparent from the graph, the wavelength distribution on the short wavelength side of the G color light incident on the left side toward the second separation dichroic mirror 31b and reaching the light valve 40g, and incident on the right side toward the second separation dichroic mirror 31b. Thus, the wavelength distribution on the short wavelength side of the G color light reaching the light valve 40g substantially matches, and appropriate filtering is achieved by the second correction dichroic mirror 38g, and the illuminance distribution on the short wavelength side of the G color light is not good. Uniformity can be reduced and uneven color in the projected image can be suppressed.

  Returning to FIG. 1, the third correction dichroic mirror 38b is parallel to the normal line N3 extending perpendicularly to the reference plane (YZ plane) including the system optical axis SA on the third optical path OP3 for B-color light. It arrange | positions so that it may extend perpendicular | vertical to the 2nd isolation | separation dichroic mirror 31b. That is, the third correction dichroic mirror 38b extends in the 45 ° azimuth between the + Y direction and the −Z direction and the opposite azimuth with the normal line N3 interposed therebetween, and is disposed perpendicular to the YZ plane. . Focusing on B-color light (particularly on the G-color light side) incident on the left side toward the second separation dichroic mirror 31b, this B-color light is incident on the second separation dichroic mirror 31b at an incident angle E (+) = 45 ° + α. Then, the light beam enters the third correction dichroic mirror 38b at an incident angle E (−) = 45 ° −α and passes through the third correction dichroic mirror 38b. On the other hand, when attention is paid to B color light (particularly on the G color light side) incident on the right side toward the second separation dichroic mirror 31a, this B color light is incident on the second separation dichroic mirror 31b at an incident angle F (−) = 45 ° −α. , Enters the third correction dichroic mirror 38b at an incident angle F (+) = 45 ° + α, and passes therethrough. In summary, when passing through the second separation dichroic mirror 31b and the third correction dichroic mirror 38b, the incident angle of the B-color light is reversed with 45 ° therebetween.

  FIG. 9 is a graph for explaining the wavelength characteristic of the transmittance of the second separation dichroic mirror 31b and the wavelength characteristic of the transmittance of the third correction dichroic mirror 38b. In the graph, the solid line indicates the transmission characteristics of B-color light or the like incident on the second separation dichroic mirror 31a at a relatively large incident angle of 50 °, and the broken line indicates the second separation dichroic mirror 31b at a relatively small incident angle of 40 °. Transmission characteristics of incident B color light and the like are shown. In the graph, the alternate long and short dash line indicates transmission characteristics of B-color light or the like incident on the third correction dichroic mirror 38b at a relatively large incident angle of 50 °, and the dotted line indicates a relatively small incident angle on the third correction dichroic mirror 38b. The transmission characteristic of B color light or the like incident at 40 ° is shown. As is apparent from the graph of FIG. 9, the edge wavelength of the wavelength region where the reflection characteristic of the second separation dichroic mirror 31b is switched moves to the B color side of the shorter wavelength as the incident angle increases, and the third correction dichroic mirror 38b. The edge wavelength in the wavelength region in which the transmission characteristics of the light source shift to the B-color side with a shorter wavelength as the incident angle increases.

  FIG. 10 is a graph showing wavelength characteristics obtained by combining the transmission of the second separation dichroic mirror 31b and the transmission of the third correction dichroic mirror 38b. The solid line in the graph indicates the wavelength distribution characteristics of the B-color light that is incident on the second separation dichroic mirror 31b at a relatively large incident angle of 50 ° and is incident on the third correction dichroic mirror 38b at a relatively small incident angle of 40 °. 1 corresponds to the B-color light incident on the left side toward the second separation dichroic mirror 31b in FIG. In addition, the broken line in the graph indicates the wavelength distribution characteristics of the B-color light that is incident on the second separation dichroic mirror 31b at a relatively small incident angle of 40 ° and is incident on the third correction dichroic mirror 38b at a relatively large incident angle of 50 °. 1 and corresponds to B-color light incident on the right side toward the second separation dichroic mirror 31b in FIG. As is apparent from the graph, the wavelength distribution of the B color light incident on the left side toward the second separation dichroic mirror 31b and reaching the light valve 40b, and the light valve incident on the right side toward the second separation dichroic mirror 31b. The wavelength distribution of the B-color light reaching 40b is almost the same, and appropriate filtering is achieved by the third correction dichroic mirror 38b. The unevenness of the illuminance distribution on the long-wavelength side of the B-color light is reduced to reduce the projection image Color unevenness can be suppressed.

  Returning to FIG. 1, in the light modulator 40, each light valve 40r, 40g, 40b individually modulates the spatial intensity distribution of the incident illumination light as a non-light-emitting light modulator. The light valves 40r, 40g, and 40b are respectively provided with three liquid crystal panels 41r (for R color light), 41g (for G color light), and 41b (for G color light) that are illuminated corresponding to the respective color lights emitted from the color separation light guide optical system 30. B color light), three incident side polarizing plates 42r (for R color light), 42g (for G color light), 42b (for B color light) arranged on the incident side of each liquid crystal panel 41r, 41g, 41b, Three output side polarizing plates 43r (for R color light), 43g (for G color light), and 43b (for B color light) are provided on the output side of each liquid crystal panel 41r, 41g, 41b.

  In the light modulator 40 described above, the R-color light beam reflected by the first separation dichroic mirror 31a enters the light valve 40r via the field lens 33r on the first optical path OP1, and the liquid crystal constituting the light valve 40r. The display area on the panel 41r is illuminated. The G-color light beam transmitted through the first separation dichroic mirror 31a and reflected by the second separation dichroic mirror 31b is incident on the light valve 40g via the field lens 33g on the second optical path OP2, and constitutes the light valve 40g. The display area on the liquid crystal panel 41g to be illuminated is illuminated. The B-color light beam transmitted through both the first and second separation dichroic mirrors 31a and 31b is incident on the light valve 40b via the field lens 33b and the like on the third optical path OP3, and constitutes the light valve 40b. The display area on 41b is illuminated. Each of the liquid crystal panels 41r to 41b modulates the spatial distribution of the polarization direction of the incident illumination light, and the polarization state of the three color illumination light beams incident on the respective liquid crystal panels 41r to 41b is adjusted on a pixel basis. At this time, the polarization direction of the illumination light incident on each of the liquid crystal panels 41r to 41b is adjusted by the incident side polarizing plates 42r to 42b, and emitted from each of the liquid crystal panels 41r to 41b by the emission side polarizing plates 43r to 43b. Modulated light having a predetermined polarization direction is extracted from the modulated light. As described above, each light valve 40r, 40g, 40b forms modulated light, that is, image light of each color corresponding thereto.

  The cross dichroic prism 50 embodies a light combining optical system for image light, and combines the image light of each color from each light valve 40r, 40g, 40b. More specifically, the cross dichroic prism 50 has a substantially square shape in plan view in which four right angle prisms are bonded together, and a pair of dielectric multilayer films intersecting in an X shape at the interface where the right angle prisms are bonded to each other. 51a and 51b are formed. One first dielectric multilayer film 51a reflects R color light, and the other second dielectric multilayer film 51b reflects B color light. The cross dichroic prism 50 reflects the R color light from the light valve 40r by the dielectric multilayer film 51a and emits it to the left in the traveling direction, and the G color light from the light valve 40g travels straight through the dielectric multilayer films 51a and 51b. The B color light from the light valve 40b is reflected by the dielectric multilayer film 51b and emitted to the right in the traveling direction. In this manner, the R color light, the G color light, and the B color light are combined by the cross dichroic prism 50 to form combined light that is image light of a color image.

  The projection lens 60 embodies a projection optical system, and enlarges the image light by the combined light formed through the cross dichroic prism 50 at a desired magnification to form a color image on a screen (not shown). Project.

  According to the projector 100 of the present embodiment described above, the color separation light guide optical system 30 cancels out the incident angle dependence of the R color light beam that is the first color separated by the first separation dichroic mirror 31a. Since the 1-correction dichroic mirror 38r is provided, even if the incident angle of the R color light to the first separation dichroic mirror 31a varies depending on the incident position, the light valve 40r is integrated to avoid the uneven distribution of the R color illumination light. Therefore, it is possible to suppress the occurrence of uneven color in the projected image with respect to the R color. In addition, according to the projector 100 of the present embodiment, the color separation light guide optical system 30 cancels the incident angle dependency of the G light beam that is the second color and the B light beam that is the third color. And the third correction dichroic mirrors 38g and 38b, even if the incident angles of the G-color light and B-color light to the first and second separation dichroic mirrors 31a and 31b differ depending on the incident position, the light valve 40r is driven by these colored lights. Therefore, it is possible to suppress the occurrence of uneven color in the projected image with respect to the G color and the B color.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments. That is, in the above embodiment, the first separation dichroic mirror 31a first separates the R color, and then the second separation dichroic mirror 31b separates the G color and the B color. It is possible to separate the G color and the R color after the separation, and in this case also, the illumination light of each color can be made uniform by the same principle.

  In the above embodiment, one or more of the correction dichroic mirrors 38r, 38g, and 38b can be omitted depending on the required accuracy.

  In the above embodiment, the first and second correction dichroic mirrors 38r and 38g are half the size of the optical path in association with the reflecting surface. However, if there is a space to be arranged independently from the reflecting surface, the reflection is possible. It is also possible to make the entire size of the optical path independent of the surface.

  Further, in the above embodiment, the third correction dichroic mirror 38b is not limited to the example of FIG. 1, and is attached to the second and third reflection mirrors 32b and 32c and extends from the center thereof in a substantially vertical direction. can do.

  In the above embodiment, an example in which the present invention is applied to a projector using a light valve made of a transmissive liquid crystal panel has been described. However, the present invention is also applicable to a projector using a light valve made of a reflective liquid crystal panel. Is possible.

  Further, as the projector, there are a front projector that projects an image from the direction of observing the projection surface and a rear projector that projects an image from the side opposite to the direction of observing the projection surface. The projector 100 shown in FIG. This configuration can be applied to both.

  In the above embodiment, only the example of the projector 100 using the three liquid crystal panels 41r to 41b has been described. However, the present invention includes a projector using one or two liquid crystal panels, and four or more liquid crystal panels. It can also be applied to the projector used.

DESCRIPTION OF SYMBOLS 10 ... Light source device, 11 ... Light emission tube, 12 ... Reflector, 20 ... Uniformation optical system, 23 ... Lens array, 23, 24 ... Lens array, 25 ... Superimposing lens, 27 ... Polarization conversion apparatus, 30 ... Color separation light guide Optical system, 31a ... first separation dichroic mirror, 31b ... second separation dichroic mirror, 32a, 32b, 32c ... reflection mirror, 33r, 33g, 33b ... field lens, 38r ... first correction dichroic mirror, 38g ... second correction Dichroic mirror, 38b ... Third correction dichroic mirror, 40 ... Light modulator, 40r, 40g, 40b ... Light valve, 41r, 41g, 41b ... Liquid crystal panel, 42r, 42g, 42b ... Incident side polarizing plate, 43r, 43g, 43b: Emission side polarizing plate, 50: Cross dichroic filter 60 ... projection lens 100 ... projector N1, N2, N3 ... normal, OP1, OP2, OP3 ... optical path, SA ... system optical axis, LL1, LL2 ... relay lens, E (+), E (-) ... incident angle of the first path, F (+), F (-) ... incident angle of the second path

Claims (9)

An illumination device that emits a luminous flux;
Of the luminous flux emitted from the illumination device, the first color separation light beam is separated by a first separation dichroic mirror, and the light beam that has passed through the first separation dichroic mirror is separated by a second separation dichroic mirror. And a color separation light-guiding optical system that separates the light beam into a third color light beam,
A first light valve, a second light valve, and a second light valve that respectively modulate the light beams of the first color, the second color, and the third color emitted from the color separation light guide optical system according to image information; A light modulator having three light valves;
A light combining optical system for combining the modulated light of the first color, the second color, and the third color respectively emitted from the first light valve, the second light valve, and the third light valve;
A projection optical system for projecting image light synthesized through the light synthesis optical system,
The color separation light guide optical system includes a correction dichroic mirror for the first color that cancels out an incident angle dependency of the light flux of the first color separated from the light flux of the second color by the first separation dichroic mirror. Have a projector. The light beam of the first color is separated from the light beams of the second color and the third color by reflection of the first separation dichroic mirror,
The correction dichroic mirror for the first color is perpendicular to the reflecting surface from a normal line that extends along the reflecting surface provided on the branched optical path of the first color and extends perpendicular to the reference surface including the system optical axis. The projector according to claim 1, wherein the projector is disposed so as to extend. The edge wavelength of the wavelength region where the reflection characteristic of the first separation dichroic mirror is switched moves to the second color side as the incident angle increases,
3. The projector according to claim 2, wherein an edge wavelength in a wavelength region where a transmission characteristic of the correction dichroic mirror for the first color is switched moves toward the second color as the incident angle increases.   The said color separation light guide optical system has the correction | amendment dichroic mirror for said 2nd colors which cancels the incident angle dependence of the light beam of said 2nd color, It is any one of Claim 1- Claim 3 characterized by the above-mentioned. Projector. The light beam of the second color is separated from the light beam of the first color by transmission through the first separation dichroic mirror,
The correction dichroic mirror for the second color is perpendicular to the reflecting surface from a normal line extending along a reflecting surface provided on the branched optical path of the second color and extending perpendicularly to the reference surface including the system optical axis. The projector according to claim 3, wherein the projector is disposed so as to extend. The edge wavelength of the wavelength region where the transmission characteristic of the first separation dichroic mirror or the reflection characteristic of the second separation dichroic mirror is switched moves to the second color side as the incident angle increases,
6. The projector according to claim 5, wherein an edge wavelength in a wavelength region where a transmission characteristic of the correction dichroic mirror for the second color is switched moves toward the second color as the incident angle increases.   The color separation light guide optical system includes a correction dichroic mirror for the third color that cancels out an incident angle dependency of the light flux of the third color separated from the light flux of the second color by the second separation dichroic mirror. The projector according to any one of claims 1 to 6, further comprising: The third color light beam is separated from the second color light beam by transmission through the second separation dichroic mirror,
The correction dichroic mirror for the third color is parallel to a normal line extending perpendicularly to the reference plane including the system optical axis and extends perpendicularly to the second separation dichroic mirror on the optical path of the third color. The projector according to claim 7, which is arranged. The edge wavelength of the wavelength region where the transmission characteristic of the second separation dichroic mirror is switched moves to the third color side as the incident angle increases,
9. The projector according to claim 8, wherein an edge wavelength in a wavelength region where a transmission characteristic of the correction dichroic mirror for the third color is switched moves toward the third color as the incident angle increases.

Images