JP2010078760A - Projector - Google Patents

Abstract

Disclosed is a projector capable of preventing deviation in illuminance distribution between colors and suppressing color unevenness.
A first optical system having an optical path length longer than that of the first optical system, and a second lens having a high refractive power and a second lens having a high refractive power are disposed on the second optical system. The light beam of the system OP2 can illuminate the liquid crystal display panel 61r in a non-inverted state between the position where the green light LG and the red light LR are branched and the incident position of the liquid crystal display panel 61r. Further, by adjusting the refractive power of both lenses 44a and 44b, the relative image formation state of each optical system OP1, OP2 and OP3 can be adjusted in advance, and the liquid crystal display panels 61g, 61r and 61b are irradiated. The magnification of the image can be made equal. Thereby, deterioration of white balance and color unevenness of the projection light of the projector 10 can be reduced.
[Selection] Figure 1

Description

  The present invention relates to a projector that modulates illumination light by a light modulation device and projects modulated image light.

  As a conventional general projector, a light source that generates substantially white light, a split polarization optical system that uniformizes and converts the light from the light source, and light that has passed through the split polarization optical system are green, blue, red A color separation light guide optical system that separates the three color light paths, three liquid crystal display panels that are respectively illuminated by the three colors of illumination light, a cross dichroic prism that synthesizes images from these three liquid crystal light valves, Some have a projection lens that projects a magnified image after synthesis.

In the projector as described above, if the relative illuminance distribution of the light beams that illuminate the liquid crystal light valves is different, the white balance of the projection screen obtained by combining them, color unevenness, and the like occur. Therefore, there is a method of correcting the illuminance distribution by making the optical path lengths of the separated green light and blue light equal and inserting a relay lens in the red optical path having a relatively long optical path length (see, for example, Patent Document 1). Further, there is a method in which the number of reflections in each optical path is unified to an odd number or even number, and the respective optical path lengths are substantially the same, and the illuminance distribution is relatively substantially equal (see, for example, Patent Document 2). ).
JP 2005-345604 A JP-A-8-254678

  However, in a projector such as Patent Document 1, since the light illuminated by the liquid crystal light valves of the blue and green light paths and the liquid crystal light valve of the red light path are relatively shifted by inversion, it is impossible to completely correct the illuminance distribution. Have difficulty. For this reason, color irregularities appear when the intensity of illumination changes due to fluctuations in the light emitting point of the light source, displacement of parts, or the like.

  In addition, the projector as in Patent Document 2 has a problem that the illuminance decreases even if the illuminance distribution is relatively equal because the optical path becomes complicated and the number of times of light reflection increases.

  In addition, although it can be considered that the optical path of each color to be separated is configured by an optical system that does not invert illumination light, that is, a non-inverted optical system, in this case, characteristic deterioration due to lens aberration occurs in a long optical path. Specifically, spherical aberration occurs due to an increase in the size of a superimposing lens in a long optical path. As a result, the overlapping of the divided light beams by the lens array (multi-lens) is deteriorated, the amount of light that can be effectively used is reduced, and the color balance is deteriorated due to the decrease in the amount of light in the long optical path.

  SUMMARY An advantage of some aspects of the invention is that it provides a projector that can prevent deviation in illuminance distribution between colors and suppress color unevenness.

  In order to solve the above problems, a first projector according to the present invention includes a light source that emits light including first color light, second color light, and third color light, first color light, second color light, and third color light. A color separation light guide optical system for separating the first color light, a first light modulation device illuminated by the first color light, a second light modulation device illuminated by the second color light, and a third light modulation illuminated by the third color light Provided between the light source and the first light modulation device and provided between the light source and the second light modulation device. The first superimposing lens disposed in the first optical system that passes the first color light. And a second superimposing lens disposed in the second optical system that allows the second color light to pass therethrough, wherein the length of the second optical system is longer than the length of the first optical system, and the second optical system has a second length. Illuminance distribution at the position of the light modulator and illuminance at the position of the first light modulator of the first optical system The fabric, in common after the image synthesis based, a lens having the strongest refractive power of the at least one lens constituting the second superimposing lens is an aspherical lens. The first superimposing lens and the second superimposing lens may share some lenses, but are substantially independent. Further, the refractive power of the lens means a power obtained by combining the lens surface on the entrance side and the lens surface on the exit side. In a thin lens, it corresponds to the sum of the powers of both lens surfaces. At this time, both the incident-side lens surface and the exit-side lens surface can be aspherical.

  In the first projector, by providing one or more condensing lenses having appropriate power (refractive power) as the second superimposing lens on the second optical system having an optical path length longer than that of the first optical system, And the focal length of the second optical system can be made equivalent to make the projected image of the light source substantially equal. Thereby, in the first and second optical systems, the illuminance distributions at the positions of the respective light modulation devices of the first and second optical systems can be made common without being inverted with respect to each other after being synthesized. As a result, it is possible to reduce white balance deterioration and color unevenness of the projection light of the projector. In addition, since the lens having a strong power (refractive power) and a large size has an aspherical surface, spherical aberration can be suppressed. Thereby, it is not necessary to take an extra margin with respect to the lens size, and the deviation of the illuminance distribution between the respective colors can be reduced without reducing the brightness. Further, in the second light modulation device on the second optical system, the overlap of the illumination light for each cell is improved, so that it is easy to align the peripheral illuminance ratio with the light modulation device on the other optical system. The difference in illuminance distribution between the color light and the third color light is further reduced, and color unevenness can be improved.

  In order to solve the above problems, a second projector according to the present invention includes a light source that emits light including first color light, second color light, and third color light, a first color light, a second color light, and a first color light. A color separation light guide optical system for separating three-color light, a first light modulation device illuminated by the first color light, a second light modulation device illuminated by the second color light, and a third illumination illuminated by the third color light. Between the light modulation device, the first superimposing lens provided between the light source and the first light modulation device and disposed in the first optical system that transmits the first color light, and between the light source and the second light modulation device And a second superimposing lens disposed in the second optical system that allows the second color light to pass therethrough, the length of the second optical system being longer than the length of the first optical system, The guided second color light is incident on the second light modulator from the position where the first color light and the second color light are branched. Illuminating the non-in-inverting state the second optical modulation device until location, the lens having the strongest refractive power of the at least one lens constituting the second superimposing lens is an aspherical lens.

  In the second projector, by providing one or more condensing lenses of appropriate power (refractive power) as the second superimposing lens on the optical path of the second optical system having an optical path length longer than that of the first optical system, The light beam of the second optical system forms the second light without forming a light source image between the position where the first color light and the second color light are branched and the incident position of the second light modulation device, that is, in a non-inverted state. The modulator device can be illuminated. Further, by adjusting in advance the relative imaging state of the first optical system and the second optical system, the magnifications of the images irradiated on the respective light modulation devices can be made equal. As a result, it is possible to reduce white balance deterioration and color unevenness of the projection light of the projector. In addition, since the lens having a large power (refractive power) and a large size has an aspherical surface, spherical aberration can be suppressed. Thereby, it is not necessary to take an extra margin with respect to the lens size, and a non-inversion optical system can be realized without reducing the brightness. Further, in the second light modulation device on the second optical system, the overlap of the illumination light for each cell is improved, so that it is easy to align the peripheral illuminance ratio with the light modulation device on the other optical system. The difference in illuminance distribution between the color light and the third color light is further reduced, and color unevenness can be improved.

  According to another aspect of the present invention, in the projector, the second superimposing lens includes a first lens on the front stage and a second lens on the rear stage, and the second lens is the first lens. It has a stronger refractive power. In this case, since the second lens has the strongest refractive power among the second superimposing lenses, the illumination light can be efficiently focused. Further, the overlapping projection magnification can be easily made equal to that of the first optical system while the length of the second optical system is relatively increased.

  In yet another aspect of the present invention, a third optical system that allows the third color light to pass between the light source and the third light modulation device is provided. Here, the third optical system can be a system equivalent to the first optical system, for example, but can also be a system equivalent to the second optical system, for example.

  In yet another aspect of the present invention, the first superimposing lens is disposed in the third optical system while being disposed in the first optical system, and the length of the first optical system is equal to the length of the third optical system. . In this case, if the length of the first optical system is equal to the length of the third optical system and the illuminance distribution is not reversed, the illuminance distribution in the first to third light modulation devices can be made substantially equal. it can.

  According to still another aspect of the present invention, a first branch mirror for branching the second optical system from another optical system is provided in the preceding stage on the optical path of the first superimposing lens and the second superimposing lens, A second branch mirror for branching the first optical system and the third optical system is provided at a subsequent stage on the optical path of the superimposing lens. In this case, by providing the respective branch mirrors at the front and rear stages of the first superimposing lens and the front stage of the second superimposing lens, the illumination light can be efficiently divided into three optical systems in stages.

  In still another aspect of the present invention, the optical system further includes a cross prism that combines the light beams of the first optical system, the second optical system, and the third optical system, and the first optical system travels straight through the cross prism, The optical system and the third optical system are reflected by the cross prism. In this case, the optical systems separated by the first and second branch mirrors can be integrated, and projection light obtained by combining the color lights can be formed.

  According to still another aspect of the present invention, the first optical system has a first superimposing lens and a first field lens upstream of the first light modulation device, and the second optical system is a second light modulation device. The first lens and the second lens as the second superimposing lens, and the second field lens, and the third optical system includes the first superimposing lens and the third lens in the front stage of the third light modulation device. And a field lens. In this case, the second optical system is provided with a first lens and a second lens, and both lenses function as a superimposing lens, whereby the second optical system has a focal length substantially equal to that of the first and third optical systems. Can be realized.

  In still another embodiment of the present invention, the second color light is red light. In this case, the light energy applied to the lens on the second optical system can be reduced by changing the light passing through the long optical path of the second optical system to red light, and the choice of materials can be increased.

  In still another aspect of the present invention, the aspheric lens is made of plastic. In this case, an aspherical lens having a large size becomes inexpensive and the cost can be suppressed.

  In still another aspect of the present invention, the optical system further includes two lens arrays arranged at positions before the first optical system and the second optical system are branched, and the first superimposing lens and the second superimposing lens are The two lens arrays are arranged downstream. In this case, by combining both lens arrays and the first and second superimposing lenses, it is possible to function as an optical integrator that equalizes incident light by dividing and superimposing.

[First Embodiment]
FIG. 1 is a conceptual diagram illustrating the configuration of the optical system of the projector according to the first embodiment of the invention.

  The projector 10 is an optical device for modulating a light beam emitted from a light source according to image information to form a color optical image and enlarging and projecting the optical image on a screen. The split polarization optical system 30, the color separation light guide optical system 40, the light modulation unit 60, the cross dichroic prism 70, and the projection optical system 80 are configured. Here, the light source lamp unit 20 and the split polarization optical system 30 constitute an illumination device that generates illumination light to be incident on the color separation light guide optical system 40 and the like.

  The light source lamp unit 20 is a light source device that collects and emits light beams emitted from the lamp body 21 to the surroundings and illuminates the light modulation unit 60 via the split polarization optical system 30 and the like. The light source lamp unit 20 includes a lamp body 21 that is a discharge arc tube, a spherical secondary mirror 22 that reflects light source light emitted forward from the lamp body 21, and light source light emitted backward from the lamp body 21. A reflecting ellipsoidal main mirror 23 and a collimating concave lens 24 are provided. In this light source lamp unit 20, the light source light emitted from the lamp body 21 as a light source is incident on the main mirror 23 via the secondary mirror 22 or directly and reflected to the front side, and is collimated by the concave lens 24. In this state, the light is emitted to the split polarization optical system 30 side.

  The split polarization optical system 30 is an optical system that splits the light beam emitted from the light source lamp unit 20 into a plurality of partial light beams and converts the illumination light into polarized light in a specific direction. 2 a multi lens 32 and a polarization conversion device 34.

  The first multi-lens 31 is also referred to as a lens array, and has a function as a light beam splitting optical element that splits a light beam emitted from the lamp body 21 into a plurality of partial light beams, and is in a plane orthogonal to the system optical axis OA. It comprises a plurality of small lenses arranged in a matrix. The contour shape of each small lens is set so as to be substantially similar to the shape of the image forming area of the liquid crystal display panels 61g, 61r, 61b constituting the light modulation unit 60 described later. The second multilens 32 is a light beam adjusting optical element that individually adjusts the divergence angles of a plurality of partial light beams divided by the first multilens 31 described above. The second multi-lens 32 is a lens array including a plurality of small lenses arranged in a matrix in a plane orthogonal to the system optical axis OA as with the first multi-lens 31, but is intended for condensing. The contour shape of each small lens does not need to correspond exactly to the shape of the image forming area of the liquid crystal display panels 61g, 61r, 61b. The first and second multi-lenses 31 and 32 and first and second superimposing lenses 43 and 44 described later function as an optical integrator that equalizes incident light by dividing and superimposing.

  The polarization conversion device 34 is formed of a PBS array and a phase difference plate, and has a role of aligning the polarization direction of each partial light beam divided by the first multi-lens 31 with one direction of linearly polarized light. Although not shown in detail, the PBS array of the polarization conversion device 34 has a configuration in which polarization separation films and reflection mirrors that are inclined with respect to the system optical axis OA are alternately arranged. The former polarization separation film transmits one polarized light beam among the P-polarized light beam and S-polarized light beam included in each partial light beam, and reflects the other polarized light beam. The reflected other polarized light beam is bent by the latter reflecting mirror, and is emitted in the emission direction of the one polarized light beam, that is, the direction along the system optical axis OA. One of the emitted polarized light beams is polarized and converted by a phase difference plate provided in a stripe shape on the light beam emission surface of the polarization conversion device 34, and the polarization directions of all the polarized light beams are aligned. By using such a polarization conversion device 34, the light beam emitted from the lamp body 21 can be aligned with a polarized light beam in one direction, so that the utilization factor of the light source light used in the light modulation unit 60 is improved. Can do.

  The color separation light guide optical system 40 is an optical system that equalizes illuminance by separating a plurality of partial light fluxes that have passed through the split polarization optical system 30 into three primary colors and superimposing them on a target illumination area. The first and second dichroic mirrors 41a and 41b, the green reflection mirror 42a, the red reflection mirrors 42b and 42c, the blue reflection mirror 42d, the first and second superimposing lenses 43 and 44, and the first , Second and third field lenses 46g, 46r, 46b.

  Among these, the first and second dichroic mirrors 41a and 41b are branch mirrors for separating the illumination light into the three primary colors, and constitute a color separation optical system. Each dichroic mirror 41a, 41b is an optical element obtained by forming on a transparent substrate a dielectric multilayer film having a wavelength selection function of reflecting a light beam in a predetermined wavelength region and transmitting a light beam in another wavelength region. Yes, they are arranged in an inclined state with respect to the system optical axis OA. The first dichroic mirror 41a reflects the red light LR among the three colors of green, red, and blue (G, R, and B) and transmits the green light LG and the blue light LB. The second dichroic mirror 41b reflects the green light LG out of the incident green light LG and blue light LB and transmits the blue light LB. As a result, the illumination light that has entered the color separation light guide optical system 40 from the light source lamp unit 20 through the split polarization optical system 30 is reflected by the first dichroic mirror 41a and reaches the liquid crystal display panel 61r that extends beyond the first dichroic mirror 41a. The red light LR guided along the second optical system OP2, and the green light transmitted through the first dichroic mirror 41a, reflected by the second dichroic mirror 41b, and led to the first optical system OP1 up to the liquid crystal display panel 61g extending beyond the first dichroic mirror 41a. The light LG is separated into blue light LB that is transmitted along the third optical system OP3 to the liquid crystal display panel 61b that extends through the first and second dichroic mirrors 41a and 41b. Here, the length of the first optical system OP1 is equal to the length of the third optical system OP3. On the other hand, the length of the second optical system OP2 is longer than the length of the first optical system OP1.

  The first superimposing lens 43 condenses a plurality of partial light fluxes of the green light LG and the blue light LB that have passed through the first dichroic mirror 41a, and the liquid crystal display panels 61g for green light LG and blue light LB, which will be described later, respectively. It is an optical element for making it overlap and inject on the image formation area of 61b. The green light LG light beam and the blue light LB light beam emitted from the first superimposing lens 43 are emitted to the first and third field lenses 46g and 46b while being made uniform. That is, the green light LG and the blue light LB that have passed through both the multi-lenses 31 and 32 and the first superimposing lens 43 pass through the first and third field lenses 46g and 46b, respectively, that is, an illumination region of the light modulation unit 60 described later. The image forming areas of the liquid crystal display panels 61g and 61b are uniformly superimposed and illuminated.

  The second superimposing lens 44 includes a first lens 44a and a second lens 44b. That is, the second superimposing lens 44 is composed of a lens group having a plurality of lenses. Similar to the first superimposing lens 43, the second superimposing lens 44 condenses a plurality of partial light beams of the red light LR that has passed through the first dichroic mirror 41a, and an image of a liquid crystal display panel 61r for red light LR described later. It is a composite optical element for making it enter and overlap on a formation area. The luminous flux of the red light LR that has passed through the second superimposing lens 44 is emitted to the second field lens 46r while being made uniform. In other words, the red light LR that has passed through the pair of multi-lenses 31 and 32 and the second superimposing lens 44 passes through the second field lens 46r, and then the illumination region of the light modulation unit 60 described later, that is, the image on the liquid crystal display panel 61r. Uniformly illuminate the formation area.

  The first lens 44a of the second superimposing lens 44 is, for example, a spherical glass lens, and both the incident surface a1 on the light incident side and the exit surface a2 on the exit side are convex. The first lens 44a has a function of slightly condensing the red light LR reflected by the first dichroic mirror 41a.

  Of the second superimposing lens 44, the second lens 44b is a plastic aspherical lens. The second lens 44b has an incident surface b1 on the light incident side and an exit surface b2 on the exit side. Either one or both of the incident surface b1 and the exit surface b2 are processed into an aspheric surface. The second lens 44b has a strong condensing effect as a result of having the strongest positive refractive power in the second superimposing lens 44 by adjusting the curvature and refractive index of the entrance surface b1 and the exit surface b2. , Responsible for the main function as a superposition lens. Here, the lens size of the second lens 44b increases as the position of the second lens 44b moves away from the first optical system OP1, that is, the G optical path. Therefore, the size of the second lens 44b is larger than the size of the first lens 44a. Since the second lens 44b condenses the red light LR collected by the first lens 44a more strongly, the NA is increased. Therefore, the occurrence of spherical aberration can be suppressed by making the second lens 44b an aspheric lens.

  In the color separation light guide optical system 40, the green reflection mirror 42a passes through the first dichroic mirror 41a and the first superimposing lens 43, and the green light LG turned in the orthogonal direction by the second dichroic mirror 41b is orthogonalized again. Folded in the direction and led to the liquid crystal display panel 61g side. The red reflection mirrors 42b and 42c are folded back in the orthogonal direction by the first dichroic mirror 41a, and the red light LR that has passed through the first lens 44a and the second lens 44b is folded back in the orthogonal direction, respectively, to be a liquid crystal display panel. Lead to 61r side. The blue reflecting mirror 42d guides the blue light LB that has passed through the first dichroic mirror 41a, the first superimposing lens 43, and the second dichroic mirror 41b to the liquid crystal display panel 61b side by folding back in the orthogonal direction. In this case, the second and third optical systems OP2 and OP3 of the red light LR and the blue light LB are parallel to the paper surface together with the first optical system OP1 of the green light LG. That is, the system optical axes OA of the respective colors corresponding to the optical systems OP1 to OP3 are housed in a common plane and are two-dimensionally arranged.

  Each field lens 46g, 46r, 46b for each color provided on the emission side of the color separation light guide optical system 40 has an appropriate convergence of each partial light beam emitted from the second multi-lens 32 and incident on the light modulation unit 60. It is provided to be a degree. Specifically, as shown in FIG. 1, the first and third field lenses 46g and 46b on the first and third optical systems OP1 and OP3 are convex lenses having positive power, and the second optical system The second field lens 46r on the system OP2 is a concave lens having negative power.

  Hereinafter, the state of light rays in the color separation light guide optical system 40 will be described. FIG. 2 is a diagram illustrating the state of light rays of the first and third optical systems OP1 and OP3. On the other hand, FIG. 3 is a diagram illustrating a state of light rays of the second optical system OP2. Here, the solid line indicates the state of parallel rays incident on the superimposing lenses 43 and 44. A two-dot chain line indicates a state of light rays incident on one end side of each liquid crystal light valve from the position of the second multi-lens 32 on the system optical axis OA, that is, on the A, C, and E sides. A one-dot chain line indicates a state of light rays incident on the other end side of each liquid crystal light valve from the position of the second multi-lens 32 on the system optical axis OA, that is, on the B, D, F side.

  As shown in FIG. 2, the first superimposing lens 43 and the first field lens 46g are arranged on the optical path of the first optical system OP1 as already described. The parallel light beam L1a incident on the first superimposing lens 43 is superimposed on the image forming area of the liquid crystal display panel 61g via the first field lens 46g and superimposed as an individual partial light beam. Further, as shown in FIG. 3, on the optical path of the second optical system OP2, the first lens 44a and the second lens 44b constituting the second superimposing lens, and the second field lens 46r are arranged. Yes. The parallel light beam L2a incident on both lenses 44a and 44b constituting the second superimposing lens 44 is superimposed and incident as an individual partial light beam on the image forming area of the liquid crystal display panel 61r via the second field lens 46r. A first superimposing lens 43 and a third field lens 46b are disposed on the optical path of the third optical system OP3. Further, as shown in FIG. 2, the parallel light beam L3a incident on the first superimposing lens 43 is superimposed and incident as an individual partial light beam on the image forming area of the liquid crystal display panel 61b via the third field lens 46b.

  In FIG. 1, light rays LTa and LTb that are part of the same partial light beam emitted from the split polarization optical system 30 are transmitted and reflected by first and second dichroic mirrors 41a and 41b to be converted into light beams of respective colors. To separate. Specifically, one light beam LTa is separated into a green light beam LGa, a red light beam LRa, and a blue light beam LBa. The other light beam LTb is separated into a green light beam LGb, a red light beam LRb, and a blue light beam LBb.

  As shown in FIG. 2, in the first and third optical systems OP1 and OP3, one of the green light beam LGa and the blue light beam LBa incident on the first superimposing lens 43 are reversed with each other in the middle of the optical systems OP1 and OP3. Without incident on the A and C sides of the liquid crystal display panels 61g and 61b of the optical systems OP1 and OP3, respectively. Similarly, the other green light beam LGb and blue light beam LBb enter the B and D sides of the liquid crystal display panels 61g and 61b of the optical systems OP1 and OP3, respectively, without being inverted in the middle of the optical systems OP1 and OP3.

  Similarly, as shown in FIG. 3, in the second optical system OP2, one red light ray LRa incident on the first lens 44a and the second lens 44b is not reversed in the middle of the second optical system OP2. Incident on the E side of the liquid crystal display panel 61r of the second optical system OP2. Similarly, the other red light beam LRb enters the F side of the liquid crystal display panel 61r of the second optical system OP2 without being inverted in the middle of the second optical system OP2. Note that whether or not the liquid crystal display panels 61g, 61r, and 61b are inverted is based on the image after the images of the liquid crystal display panels 61g, 61r, and 61b are combined by the cross dichroic prism 70.

  Here, the state of the light beam of the second optical system OP2 in FIG. 3 will be described in more detail. FIG. 4 is a conceptual diagram showing a state of light rays by enlarging a part of the second optical system OP2. FIG. 5 is a conceptual diagram showing the state of light rays of the optical system OPx in which the second lens 44a in FIG. 4 is replaced with a lens 44c that is not an aspheric lens. 6A is an enlarged view showing the degree of convergence of light rays on the liquid crystal display panel 61r of the second optical system OP2 in FIG. 4, and FIG. 6B is a diagram of the optical system OPx in FIG. It is an enlarged view which shows the convergence degree of the light ray on the liquid crystal display panel 61r.

  In the second optical system OP2, the second lens 44b is a lens having the most refractive power in the second optical system OP2. Therefore, as shown in FIG. 4, the size of the second lens 44b is larger than that of the first lens 44a and the like. However, since the second lens 44b is an aspheric lens, as shown in FIG. 6A, the convergence degree of the light beam on the liquid crystal display panel 61r of the second optical system OP2 (the degree of concentration at the condensing point). ) Is as small as 0.5 mm, for example, and the occurrence of spherical aberration is suppressed. Therefore, it is possible to prevent the superposition state from being deteriorated by the second lens 44b.

  On the other hand, when the lens 44c corresponding to the second lens 44b is not an aspheric lens, as shown in FIGS. 5 and 6B, the convergence degree of the light beam on the liquid crystal display panel 61r of the optical system OPx is, for example, It becomes as large as 6 mm and the spherical aberration increases. As a result, the superposition state is deteriorated and the amount of light is reduced. As a result, there arises a problem that the ambient illumination ratio changes.

  Returning to FIG. 1, the light modulation unit 60 includes three liquid crystal display panels 61g, 61r, and 61b on which the three colors of illumination lights LG, LR, and LB are respectively incident. Here, the green light LG liquid crystal display panel 61g and the pair of polarizing filters 62g and 62g sandwiching the green light LG liquid crystal light valve for two-dimensionally modulating the luminance of illumination light based on image information. Configure. The liquid crystal display panel 61r for red light LR and the pair of polarizing filters 62r and 62r sandwiching the liquid crystal display panel 61r also constitute a liquid crystal light valve for red light, and similarly, a liquid crystal display panel 61b for blue light LB and this A pair of polarizing filters 62b and 62b sandwiching the liquid crystal also constitutes a blue liquid crystal light valve. Each of the liquid crystal display panels 61g, 61r, 61b is a liquid crystal which is an electro-optical material sealed between a pair of transparent glass substrates. For example, a polysilicon TFT is used as a switching element according to a given image signal. The polarization direction of the polarized light beam incident on each of them is modulated.

  The green light LG propagating through the first optical system OP1 enters the illumination area of the liquid crystal display panel 61g via the first superimposing lens 43, the green reflection mirror 42a, and the first field lens 46g, and enters the liquid crystal display panel 61g. Illuminate the image forming area. The red light LR propagating through the second optical system OP2 passes through the first lens 44a, the red reflection mirror 42b, the second lens 44b, the red reflection mirror 42c, and the second field lens 46r, and the liquid crystal display panel 61r. The image forming area in the liquid crystal display panel 61r is illuminated. The blue light LB propagating through the third optical system OP3 enters the illumination area of the liquid crystal display panel 61b through the first superimposing lens 43, the second dichroic mirror 41b, the blue reflecting mirror 42d, and the third field lens 46b. The image forming area in the liquid crystal display panel 61b is illuminated. Each of the liquid crystal display panels 61g, 61r, and 61b is a non-light-emitting transmissive light modulation device for changing the spatial distribution of the polarization direction of incident illumination light. Illumination lights LG, LR, and LB incident on the liquid crystal display panels 61g, 61r, and 61b, respectively, in pixel units according to drive signals or control signals input as electrical signals to the liquid crystal display panels 61g, 61r, and 61b. Is used to adjust the polarization state. At that time, the polarization direction of the illumination light incident on the liquid crystal display panels 61g, 61r, 61b is adjusted by the polarizing filters 62g, 62r, 62b, and the liquid crystal display panels 61g, 62r, 62b are adjusted by the polarizing filters 62g, 62r, 62b. Modulated light having a predetermined polarization direction is extracted from the light emitted from 61r and 61b.

  The cross dichroic prism 70 is a light combining optical system that forms a color image by combining optical images modulated for the respective color lights emitted from the polarization filters 62g, 62r, and 62b. The cross dichroic prism 70 has a substantially square shape in plan view in which four right angle prisms are bonded together, and a pair of dielectric multilayer films 71 and 72 intersecting in an X shape are formed at the interface where the right angle prisms are bonded to each other. Is formed. One first dielectric multilayer film 71 reflects the blue light LB, and the other second dielectric multilayer film 72 reflects the red light LR. The cross dichroic prism 70 reflects the blue light LB from the liquid crystal display panel 61b by the first dielectric multilayer film 71 and emits the red light LR from the liquid crystal display panel 61r to the right in the traveling direction. The light is reflected by the film 72 and emitted to the left in the traveling direction, and the green light LG from the liquid crystal display panel 61g is caused to travel straight and emit through the first and second dielectric multilayer films 71 and 72. That is, the red light LR and the blue light LB are guided to the cross dichroic prism 70 from the direction in which they are bent in the cross dichroic prism 70, and the green light LG is crossed from the direction in which the green light LG travels straight in the cross dichroic prism 70. 70.

  The image light combined by the cross dichroic prism 70 in this way is projected as a color image on a screen (not shown) at an appropriate magnification through a projection optical system 80 as a magnification projection lens.

  In the projector 10 described above, the first lens 44a having a low refractive power and the second lens 44b having a high refractive power are disposed on the second optical system OP2 having an optical path length longer than that of the first optical system OP1. The light beam of the second optical system OP2 can illuminate the liquid crystal display panel 61r in a non-inverted state between the position where the green light LG and the red light LR are branched and the incident position of the liquid crystal display panel 61r. Further, by adjusting the refractive power of both lenses 44a and 44b, the relative image formation state of each optical system OP1, OP2 and OP3 can be adjusted in advance, and the liquid crystal display panels 61g, 61r and 61b are irradiated. The magnification of the image can be made equal. Thereby, deterioration of white balance and color unevenness of the projection light of the projector 10 can be reduced.

  Further, since the second lens 44b having a large refractive power and a large size has an aspherical surface, it is possible to suppress spherical aberration on the liquid crystal display panel 61r. Accordingly, it is not necessary to take an extra margin with respect to the lens size, and the second optical system OP2 that is a non-inversion optical system can be realized without reducing the brightness.

  Further, in the liquid crystal display panel 61r on the second optical system OP2, the overlapping of the luminous flux for each cell is improved, so that it becomes easy to align the peripheral illumination ratio with the liquid crystal display panels 61g and 61b on the other optical systems OP1 and OP3. Therefore, the difference in illuminance distribution among the liquid crystal display panels 61g, 61r, 61b is further reduced, and the color unevenness of the projector 10 can be improved.

  Moreover, since the light energy applied to the lens on the second optical system OP2 is reduced by changing the light passing through the long optical path of the second optical system OP2 to the red light LR, a relatively inexpensive plastic lens can be used. Become. Thereby, even if an aspherical lens having a large size is required, the degree of freedom in processing can be ensured and the cost can be suppressed.

[Second Embodiment]
Hereinafter, a projector according to a second embodiment of the invention will be described. Note that the projector according to the second embodiment is obtained by partially changing the projector 10 according to the first embodiment, and parts that are not particularly described are the same as those in the first embodiment.

  FIG. 7 is a conceptual diagram illustrating the configuration of the optical system of the projector 110 according to the second embodiment. The projector 110 of this embodiment includes a light source lamp unit 20, a split polarization optical system 30, a color separation light guide optical system 140, a light modulation unit 60, a cross dichroic prism 70, and a projection optical system 80. Configured.

  The color separation light guide optical system 140 includes a cross dichroic mirror 141, red reflection mirrors 42b and 42c, blue reflection mirrors 42d and 42e, first, second, and third superimposing lenses 43, 44, and 45. , First, second, and third field lenses 46g, 46r, and 46b.

  Among these, the cross dichroic mirror 141 is a color separation optical system for separating illumination light into three primary colors. The cross dichroic mirror 141 is formed of a pair of dichroic mirrors 141a and 141b that intersect in an X shape. One first dichroic mirror 141a reflects red light LR, and the other second dichroic mirror 141b reflects blue light LB. The first and second dichroic mirrors 141a and 141b transmit the green light LG. As a result, the illumination light that has entered the color separation light guide optical system 140 from the light source lamp unit 20 through the split polarization optical system 30 is reflected by the first dichroic mirror 141a and then travels to the second optical system OP2 that extends beyond it. The guided red light LR, the blue light LB that is reflected by the second dichroic mirror 141b and guided to the third optical system OP3, and the first and second dichroic mirrors 141a and 141b are transmitted therethrough and extend beyond them. The light is separated into green light LG guided to the first optical system OP1.

  The first superimposing lens 43 is an optical element that condenses a plurality of partial light beams of the green light LG that has passed through the cross dichroic mirror 141 and causes the light to overlap and enter the image forming region of the liquid crystal display panel 61g. The light beam of the green light LG emitted from the first superimposing lens 43 is incident on the first field lens 46g while being made uniform. That is, the green light LG that has passed through both the multi-lenses 31 and 32 and the first superimposing lens 43 is uniformly superimposed on the illumination area of the light modulator 60, that is, the image forming area of the liquid crystal display panel 61g, via the first field lens 46g. Illuminate.

  The second superimposing lens 44 includes a first lens 44a and a second lens 44b. Similar to the first superimposing lens 43, the second superimposing lens 44 collects a plurality of partial light beams of the red light LR that has passed through the cross dichroic mirror 141, and superimposes them on the image forming area of the liquid crystal display panel 61r. It is an optical element for making it. The light beam of the red light LR emitted from the second superimposing lens 44 is incident on the second field lens 46r while being made uniform. That is, the red light LR that has passed through both the multi-lenses 31 and 32 and the second superimposing lens 44 is uniformly superimposed on the illumination area of the light modulator 60, that is, the image forming area of the liquid crystal display panel 61r, via the second field lens 46r. Illuminate.

  The second lens 44b of the second superimposing lens 44 is a plastic aspheric lens, has the strongest positive refractive power in the second superimposing lens 44, and has a main function as a superimposing lens.

  Similar to the second superimposing lens 44, the third superimposing lens 45 is composed of a third lens 45a and a fourth lens 45b. Further, the blue light LB that has passed through both the multi-lenses 31 and 32 and the third superimposing lens 45 is uniformly superimposed on the illumination area of the light modulator 60, that is, the image forming area of the liquid crystal display panel 61b, via the third field lens 46b. Illuminate.

  The fourth lens 45b of the third superimposing lens 45 is a plastic aspheric lens, has the strongest positive refractive power in the third superimposing lens 45, and has a main function as a superimposing lens.

  The second and fourth lenses 44b and 45b are larger in size than the first and third lenses 44a and 45a.

  The red reflection mirrors 42b and 42c are folded back in the orthogonal direction by the first dichroic mirror 141a, and the red light LR that has passed through the first lens 44a and the second lens 44b is folded back again in the orthogonal direction, respectively, to be a liquid crystal display panel. Lead to 61r side. The blue reflection mirrors 42d and 42e are folded back in the orthogonal direction by the second dichroic mirror 141b, and the blue light LB that has passed through the third lens 45a and the fourth lens 45b is folded back in the orthogonal direction, respectively, to be a liquid crystal display panel. Lead to the 61b side.

  Each field lens 46g, 46r, 46b for each color provided on the emission side of the color separation light guide optical system 140 has an appropriate convergence of each partial light beam emitted from the second multi-lens 32 and incident on the light modulation unit 60. It is provided to be a degree. Specifically, as shown in FIG. 7, the first field lens 46g on the first optical system OP1 is a convex lens having positive power, and the second field lens 46r on the second and third optical systems OP2 and OP3. , 46b are concave lenses having negative power.

  In the light modulation unit 60, the green light LG guided to the first optical system OP1 enters the illumination area of the liquid crystal display panel 61g via the first superimposing lens 43 and the first field lens 46g, and enters the liquid crystal display panel 61g. Illuminate the image forming area. The red light LR guided to the second optical system OP2 is transmitted through the first lens 44a, the red reflection mirror 42b, the second lens 44b, the red reflection mirror 42c, and the second field lens 46r. The light enters the illumination area 61r and illuminates the image forming area in the liquid crystal display panel 61r. The blue light LB guided to the third optical system OP3 is transmitted through the third lens 45a, the blue reflection mirror 42d, the fourth lens 45b, the blue reflection mirror 42e, and the third field lens 46b. The light enters the illumination area 61b and illuminates the image forming area in the liquid crystal display panel 61b.

  In the projector 110 described above, the first and third lenses 44a and 45a having a weak refractive power and the strong refractive power are respectively provided on the second and third optical systems OP2 and OP3 having an optical path length longer than that of the first optical system OP1. By disposing the second and fourth lenses 44b and 45b, the liquid crystal display panels 61r and 61b from the position where the light beams of the second and third optical systems OP2 and OP3 branch off the respective color lights LG, LR, and LB. It is possible to illuminate the liquid crystal display panels 61r and 61b in a non-inverted state until the incident position. Further, by adjusting the refractive power of each lens 44a, 44b, 45a, 45b, the relative image formation state of each optical system OP1, OP2, OP3 can be adjusted in advance, and each liquid crystal display panel 61g, 61r, 61b can be adjusted. It is possible to make the magnification of the image irradiated to the same. Thereby, deterioration of white balance and color unevenness of the projection light of the projector 10 can be reduced.

  In addition, since the second and fourth lenses 44b and 45b having a strong refractive power and a large size have aspherical surfaces, it is possible to suppress spherical aberration on the liquid crystal display panels 61r and 61b, respectively. Thereby, it is not necessary to take an extra margin with respect to the lens size, and the second and third optical systems OP2 and OP3 that are non-inversion optical systems can be realized without reducing the brightness.

  Further, in the liquid crystal display panels 61r and 61b on the second and third optical systems OP2 and OP3, the overlapping of the luminous flux for each cell is improved, so that it is easy to align the peripheral illuminance ratio with the liquid crystal display panel 61g on the other optical system OP1. Become. Therefore, the difference in illuminance distribution among the liquid crystal display panels 61g, 61r, 61b is further reduced, and the color unevenness of the projector 110 can be improved.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the gist thereof. Such modifications are also possible.

  That is, in the above embodiment, the case where the green light LG, the red light LR, and the blue light LB are guided to the first optical system OP1, the second optical system OP2, and the third optical system OP3, respectively, is described. These combinations can be freely changed by changing the design of the first and second dichroic mirrors 41a and 41b, which are optical systems. For example, the blue light LB and the green light LG can be guided to the long third optical system OP3. However, when improving the illumination intensity of the projected image, it is desirable to guide the green light LG to the first optical system OP1.

  Moreover, in the said embodiment, although the cross dichroic prism 70 was used for the synthesis | combination of illumination light, you may use a cross dichroic mirror. In the second embodiment, the cross dichroic mirror 141 is used to separate illumination light, but a cross dichroic prism may be used.

  In the projectors 10 and 110 of the above-described embodiment, a high-pressure mercury lamp or the like is used because the lamp body 21 of the light source lamp unit 20 can emit high-intensity light over the wavelengths of each color. Various lamps capable of obtaining substantially white illumination light and solid light emitting elements such as LEDs can be used. In addition, as the primary mirror 23, various reflectors such as a parabolic surface can be used without being limited to an elliptical surface. When the parabolic main mirror 23 is used, a parallel light beam can be emitted from the light source lamp unit 20 without providing the concave lens 24 or the like after the main mirror 23.

  In the projectors 10 and 110 according to the above-described embodiments, the split polarization optical system 30 includes the first and second multilenses 31 and 32 and the polarization conversion device 34. However, the first and second multilenses 31 and 32 are provided. Etc. can be omitted, or it can be replaced by a rod integrator.

  In the present invention, the positions of the first superimposing lens 44, the second superimposing lens 44, and the like uniformly illuminate the illumination area of the light modulator 60, that is, the image forming areas of the liquid crystal display panels 61g, 61r, 61b of the respective colors. Any position is acceptable.

  Further, the present invention can be applied to a front projection type projector that projects from the side that observes the projected image, and a rear projection type projector that projects from the side opposite to the side that observes the projected image.

It is a conceptual diagram explaining the structure of the optical system of the projector which concerns on 1st Embodiment. It is a figure showing the state of the light ray of a 1st and 3rd optical system. It is a figure showing the state of the light ray of a 2nd optical system. It is a conceptual diagram explaining the state of the light ray of a 2nd optical system. It is a conceptual diagram explaining the state of the light ray of the optical system which does not have an aspherical lens. (A), (B) is an enlarged view which shows the convergence degree of the optical system of FIG.4 and FIG.5, respectively. It is a conceptual diagram explaining the structure of the optical system of the projector which concerns on 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,110 ... Projector, 20 ... Light source lamp unit, 30 ... Split polarization optical system, 40, 140 ... Color separation light guide optical system, 41a, 141a ... First dichroic mirror, 41b, 141b ... Second dichroic mirror, 42a Reflective mirror for green, 42b, 42c ... Reflective mirror for red, 42d, 42e ... Reflective mirror for blue, 43, 44, 45 ... Superimposing lens, 46g, 46r, 46b ... Field lens, 60 ... Light modulator, 61g, 61r, 61b ... Liquid crystal display panel, 62g, 62r, 62b ... Polarizing filter, 70 ... Cross dichroic prism, 141 ... Cross dichroic mirror, 71, 72 ... Dielectric multilayer film, 80 ... Projection optical system, LB ... Blue light, LG ... green light, LR ... red light, OA ... system optical axis, P1～OP3 ... first to third optical system

Claims (11)

A light source that emits light including first color light, second color light, and third color light;
A color separation light guide optical system for separating the first color light, the second color light, and the third color light;
A first light modulation device illuminated by the first color light;
A second light modulation device illuminated by the second color light;
A third light modulation device illuminated by the third color light;
A first superimposing lens disposed in a first optical system that is provided between the light source and the first light modulation device and transmits the first color light;
A second superimposing lens disposed between the light source and the second light modulation device and disposed in a second optical system that transmits the second color light;
With
The length of the second optical system is longer than the length of the first optical system,
The illuminance distribution at the position of the second light modulation device of the second optical system and the illuminance distribution at the position of the first light modulation device of the first optical system are common on the basis of image synthesis,
A projector in which a lens having the strongest refractive power among at least one lens constituting the second superimposing lens is an aspherical lens. A light source that emits light including first color light, second color light, and third color light;
A color separation light guide optical system for separating the first color light, the second color light, and the third color light;
A first light modulation device illuminated by the first color light;
A second light modulation device illuminated by the second color light;
A third light modulation device illuminated by the third color light;
A first superimposing lens disposed in a first optical system that is provided between the light source and the first light modulation device and transmits the first color light;
A second superimposing lens disposed between the light source and the second light modulation device and disposed in a second optical system that transmits the second color light;
With
The length of the second optical system is longer than the length of the first optical system,
The second color light guided to the second optical system is non-inverted between a position where the first color light and the second color light are branched and an incident position of the second light modulation device. Illuminates the two-light modulator,
A projector in which a lens having the strongest refractive power among at least one lens constituting the second superimposing lens is an aspherical lens. The second superimposing lens is composed of a first lens on the front stage side and a second lens on the rear stage side,
The projector according to claim 1, wherein the second lens has a refractive power stronger than that of the first lens.   4. The projector according to claim 1, wherein a third optical system that passes the third color light is provided between the light source and the third light modulation device. 5.   The first superimposing lens is disposed in the third optical system while being disposed in the first optical system, and the length of the first optical system is equal to the length of the third optical system. Projector.   A first stage mirror on the optical path of the first superimposing lens and the second superimposing lens having a first branching mirror for branching the second optical system from another optical system; The projector according to claim 4, further comprising a second branch mirror for branching the first optical system and the third optical system. A cross prism for combining the light beams of the first optical system, the second optical system, and the third optical system;
The projector according to any one of claims 4 to 6, wherein the first optical system travels straight through the cross prism, and the second optical system and the third optical system are reflected by the cross prism. . The first optical system includes a first superimposing lens and a first field lens before the first light modulation device,
The second optical system includes a first lens and a second lens as the second superimposing lens, and a second field lens in a stage preceding the second light modulation device,
The projector according to any one of claims 4 to 7, wherein the third optical system includes a first superimposing lens and a third field lens in a stage preceding the third light modulation device.   The projector according to any one of claims 1 to 8, wherein the second color light is red light.   The projector according to claim 1, wherein the aspheric lens is made of plastic. Two lens arrays arranged at a position before the first optical system and the second optical system branch;
The projector according to any one of claims 1 to 10, wherein the first superimposing lens and the second superimposing lens are arranged at a subsequent stage of the two lens arrays.

Images