JP6124653B2 - Illumination optical system and projection display device - Google Patents

Description

  The present invention relates to an illumination optical system and a projection display device having the illumination optical system.

  In FIG. 1 and FIG. 8, a patent document 1 discloses a projection display device configured so that an illumination range for an image modulation element can be moved by moving a folding mirror disposed in the vicinity of the subsequent stage of an integrator. Yes. In Patent Document 1, one lens group (for example, the condenser lens 4) of the condensing lens system is provided in the vicinity of the bending mirror, and the other lens group (for example, the field lens 16) is provided as an image modulation element (for example, the first lens group). 2 disposed near the liquid crystal panel 8). The color separation optical elements (first dichroic mirror 5 and second dichroic mirror 6) are arranged between the two lens groups of the condenser lens system.

Japanese Patent Laid-Open No. 11-101965

  The configuration as in Patent Document 1 has a feature that the entire length can be shortened, but the configuration shown in FIG. 1 has a problem that the folding mirror becomes large in order to receive the expanded light flux from the integrator. Further, in the configuration shown in FIG. 8 of Patent Document 1, it is necessary to increase the amount of movement of the mirror when adjusting the illumination range of the image modulation element, which requires adjustment time, the adjustment mechanism becomes large, and color unevenness occurs. There are problems such as being likely to occur.

  It is an object of the present invention to provide an illumination optical system and a projection display device that can reduce the size of a mirror that adjusts the illumination range of an image modulation element and has high movement sensitivity of the illumination range.

  An illumination optical system according to the present invention is an illumination optical system that illuminates an image modulation element with light from a light source, has two lens groups having positive power, and collects light beams from the light source on the image modulation element. A condensing lens system that emits light, a mirror that is disposed between the two lens groups and adjusts an illumination range for the image modulation element, and a driving unit that rotationally drives the mirror, and the condensing lens When the focal length of the system is F and the distance on the optical axis from the surface closest to the image modulation element of the condenser lens system to the image modulation element is Bk, the following conditional expression is satisfied: And

  0.8 ≦ Bk / F

  ADVANTAGE OF THE INVENTION According to this invention, the mirror which adjusts the illumination range of an image modulation element can be reduced in size, and the illumination optical system and projection type display apparatus with high movement sensitivity of an illumination range can be provided.

It is sectional drawing of the projection type display apparatus of this invention. Example 1 It is a figure which shows the movement of the illumination range with respect to the inclination of the mirror shown in FIG. Example 1 It is a figure which shows the relationship between two condenser lenses shown in FIG. 1, and an image surface. Example 1 It is sectional drawing of the projection type display apparatus of this invention. (Example 2) It is a figure which shows the characteristic of the synthetic | combination prism shown in FIG. (Example 2) 10 is a diagram for explaining a configuration of Patent Document 1. FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an optical path diagram of a liquid crystal projector which is an example of a projection display device (image display device) according to the first embodiment. The projection display device includes a light source unit, an illumination optical system, a reflective image modulation element (image modulation element) 12, and a projection lens (projection optical system) 13.

  The light source unit includes a light source 1 and a parabolic reflector 2, and a light beam emitted from the light source (light emitting unit of the lamp) 1 in all directions is emitted by the parabolic reflector 2 as substantially parallel light. The light source 1 of the present embodiment is an ultrahigh pressure mercury lamp, but is not limited thereto, and an LED or a laser light source may be used.

  The illumination optical system illuminates the reflective image modulation element 12 with light from the light source unit, and the first lens array 3, the second lens array 4, the polarization conversion element 5, the first condenser lens 6, the mirror 7, The second condenser lens 8 and the like are included. If necessary, the illumination optical system may include a UV-IR (ultraviolet / infrared light) cut filter (for example, between the light source unit and the first lens array 3).

  The parallel light beam from the paraboloid reflector 2 is divided into a plurality of partial light beams by the first lens array 3, and each partial light beam is condensed. Each divided light beam is condensed near the second lens array 4, and each partial light beam forms a light source image (secondary light source image). The split light beams emitted from the second lens array 4 are aligned in the polarization direction perpendicular to the paper surface by the polarization conversion element 5.

  The light emitted from the polarization conversion element 5 is collected by the first condenser lens 6 and the second condenser lens 8 having positive power, and illuminates the reflective liquid crystal display element 12 in a superimposed manner. The first lens array 3 and the second lens array 4 are integrators that make light from the light source unit uniform. In FIG. 1, a one-dimensional lens array is formed. Is not limited to that shown in FIG.

  The first condenser lens (first lens group) 6 and the second condenser lens (second lens group) 8 constitute a condenser lens system. The first condenser lens 6 and the second condenser lens 8 are two lens groups having positive power, and each lens group is composed of one or a plurality of lenses. The first condenser lens 6 is a plano-convex lens with the convex surface facing the mirror 7 side, and the second condenser lens 8 is a biconvex lens, but is limited to these as long as they are two lens groups having positive power. Not.

  The mirror 7 is disposed between the two lens groups of the condenser lens system, and adjusts the illumination range for the reflective liquid crystal display element 12. The mirror 7 is a total reflection mirror, and guides the incident light beam from the first condenser lens 6 to the second condenser lens 8 by bending it by approximately 90 degrees. The mirror 7 is rotationally driven by the driving means 7a. The structure of the drive means 7a is not specifically limited.

  During the condensing, the reflective liquid crystal display element 12 is illuminated in a superimposed manner via the polarizing plate 9, the polarizing beam splitter 10, and the quarter wave plate.

  In the configuration of FIG. 1 of Patent Document 1, the first condenser lens 6 is not provided as in this embodiment, and a mirror is disposed at a position where the light beam emitted from the second fly-eye lens spreads, The mirror becomes large. On the other hand, in the present embodiment, the mirror 7 is disposed after the first condenser lens 6 having positive power and receives the condensed light beam, so that the mirror 7 can be made smaller than that in Patent Document 1.

  FIG. 6 is a schematic configuration diagram of the condenser lens to field lens of FIG. In FIG. 6, the mirror must be arranged at a position about 1/5 to 1/4 of the distance between the condenser lens and the field lens, and the sensitivity when the mirror is tilted is shown in FIG. It becomes smaller than the configuration shown in FIG. The amount of movement of the illumination range on the display element when the mirror is tilted by 1 ° is F · tan (2 °) in the configuration of FIG. In the configuration of FIG. 8, (0.75 to 0.8) · F · tan (2 °).

  2A and 2B are partial enlarged views of FIG. 1 showing movement of the illumination range of the reflective liquid crystal display element 12 with respect to the tilt of the mirror 7. In FIG. 2A, the drive means 7a shows the mirror 7 around an axis perpendicular to the plane (paper surface) including the optical axes of the first condenser lens 6 and the second condenser lens 8 as indicated by an arrow. And so on. The mirror 7 moves the illumination range of the reflective liquid crystal display element 12 in the direction of the arrow. In FIG. 2B, the driving means 7 a is parallel to the plane (paper surface) including the optical axes of the first condenser lens 6 and the second condenser lens 8 and parallel to the reflecting surface of the mirror 7. The mirror 7 is rotationally driven around the axis as indicated by the arrow. The mirror 7 moves the illumination range of the reflective liquid crystal display element 12 in the direction of the arrow.

  The combined focal length of the first condenser lens 6 and the second condenser lens 8 is F, and the distance on the optical axis from the surface closest to the display element of the second condenser lens 8 to the reflective liquid crystal display element 12 is shown. When Bk is set, the following equation is satisfied.

0.8 ≦ Bk / F (1)
FIG. 3 is a schematic configuration diagram from the first condenser lens 6 to the image plane. In FIG. 3, the first condenser lens 6 has a focal length f1, and the second condenser lens 8 has a focal length f2. A circle indicates the optical path bending position by the mirror 7. The amount of movement of the illumination range (on the image plane) when the mirror 7 is tilted by 1 ° is
(d / 2) × tan (2 °) + Bk × (tan (2 ° -arctan ((d / 2 × tan (2 °) / f2)
It is represented by Note that the inclination of the mirror 7 may be any of the inclinations shown in FIGS. If you expand this,
(d / 2) × tan (2 °) + Bk × (tan (2 °)-(d / 2 × tan (2 °) / f2)) / (1+ (d / 2f2) × (tan2 °) ^ 2)
It is represented by In the denominator of the second term, (tan2 °) ^ 2 << 1, so
(d / 2) × tan (2 °) + Bk × (tan (2 °)-(d / 2 × tan (2 °) / f2)) = tan (2 °) × (Bk + (d / 2) × (1-Bk / f2))
become that way. Since Bk <f2, it is sufficient that at least 0.8 ≦ Bk / F to increase the movement sensitivity of the illumination range with respect to the configuration of FIG. As a reference example, Table 1 shows the movement sensitivity when the combined focal length F is 80 mm and the focal length f2 of the second lens group is 100 mm. A is the amount of movement of the illumination range when the mirror is tilted by 1 °, B is the maximum amount of movement under the condition of the composite focal length of 80 mm, and A / B is the sensitivity to the maximum amount of movement F · tan (2 °). The amount of decrease. In the configuration of FIG. 8 of Patent Document 1, the sensitivity of A / B is 0.75 to 0.8 relative to FIG. 1 of Patent Document 1 (movement amount F · tan (2 °)). However, it can be seen that, when the configuration satisfying the conditional expression of 0.8 ≦ Bk / F <1 as in the present embodiment is taken, it is exceeded. Moreover, it is preferable that the conditional expression 0.85 ≦ Bk / F <1 is further satisfied.

  In Table 1, a configuration in which Bk / F is less than 0.80 is not adopted in this embodiment. The value of Bk / F is adjusted by adjusting the power (refractive index) and Bk of the first condenser lens 6 and the second condenser lens 8, respectively.

  FIG. 4 shows an optical path diagram of the projection display apparatus of the second embodiment. The projection display device includes a light source unit, an illumination optical system, reflective image display elements 33R, 33G, and 33B, and a projection lens (projection optical system) 36.

  The light source unit includes a light source 21 corresponding to the light source 1 and a parabolic reflector 22 corresponding to the parabolic reflector 2. The light beam emitted from the light source (light emitting part of the lamp) 21 in all directions is emitted as substantially parallel light by the parabolic reflector 22.

  The illumination optical system illuminates the image modulation element, and the first lens array 23, the second lens array 24, the polarization conversion element 25, the first condenser lens 26, the mirror 27, the second condenser lens 28, and color separation. An optical element for performing the above. These optical elements 23 to 28 correspond to the optical elements 3 to 8 of the first embodiment and have the same function and effect. The mirror 27 is rotationally driven by the driving means 27a, and the tilt of the mirror 27 and the movement of the illumination range of the display element are the same as in the first embodiment.

  Since the mirror 27 is disposed after the first condenser lens 26 having a positive power and receives the condensed light flux, the mirror 27 can be made smaller than that in Patent Document 1. Further, when the combined focal length of the first condenser lens 26 and the second condenser lens 28 is F, and the distance from the surface of the second condenser lens 28 closest to the display element to the display element is Bk, 0.8 ≦≦ Since Bk / F is satisfied, the same effect as in Example 1 can be obtained.

  In this embodiment, a color separation optical element is disposed between the condenser lens system and the display element to reduce color unevenness. Specifically, the light emitted from the second condenser lens 28 is reflected by a dichroic mirror 29 that reflects green light (G color light) and transmits red light (R color light) and blue light (B color light). Incident. The dichroic mirror 29 is a color separation optical element.

  The G color light reflected from the dichroic mirror 29 is transmitted through the polarizing plate 30, enters the first polarizing beam splitter 31, and the S-polarized light is reflected by the polarization separation surface, so that a reflective liquid crystal display element for G ( Liquid crystal panel) 33G. In the reflective liquid crystal display element 33G for G, the G color light is image-modulated and reflected. Of the image-modulated G reflected light, the S-polarized light component is again reflected on the polarization separation surface of the first polarization beam splitter 31, returned to the light source side, and removed from the projection light. On the other hand, the P-polarized component of the image-modulated G reflected light is transmitted through the polarization separation surface of the first polarization beam splitter 31, and the polarization direction is converted to S-polarized light by the half-wave plate 34. Head to 35.

  The combining prism 35 combines the G color light (the light in the first wavelength region) with the R color light (the light in the second wavelength region) and the B color light (the light in the third wavelength region), and functions as a combining unit. . The combining prism 35 has an optical surface that also has polarization separation characteristics shown in FIG. 5, and transmits dichroic mirrors for B and G color light, transmits P polarization for R color light, and reflects S polarization. It has the characteristics of a polarizing beam splitter.

  FIG. 5 is a graph showing the relationship between the wavelength (nm) (horizontal axis) and the transmittance (%) (vertical axis) of light incident on the combining prism 35. For the G color light, the combining prism 35 reflects both the P-polarized light and the S-polarized light and guides them to the projection lens 36. The combining prism 35 transmits the P-polarized light to the projection lens 36 for the R color light, but reflects the S-polarized light. That is, the combining prism 35 guides one of P-polarized light and S-polarized light to the projection lens 36 for the R color light. Further, the composite prism 35 transmits both the P-polarized light and the S-polarized light to the B color light and guides them to the projection lens 36.

  A quarter-wave plate 32G provided between the first polarizing beam splitter 31 and the G-use reflective liquid crystal display element 33G in a state where all the polarization components are converted to S-polarized light (a state in which black is displayed). The slow axis is adjusted in a predetermined direction. Thereby, it is possible to suppress the influence of disturbance of the polarization state generated in the first polarizing beam splitter 31 and the reflective liquid crystal display element 33G for G. The G color light emitted from the first polarizing beam splitter 31 is reflected by the combining prism 35 and reaches the projection lens 36.

  On the other hand, the R and B color lights transmitted through the dichroic mirror 29 enter the polarizing plate 41 that transmits the S-polarized light, and then enter the color selective phase difference plate 42. The color-selective phase difference plate 42 has a function of rotating the polarization direction of only the R color light by 90 degrees, whereby the R color light is converted to P-polarized light, and the B color light is converted to S-polarized light. Is incident on. The R color light incident on the second polarization beam splitter 43 as P-polarized light is transmitted through the polarization separation surface of the second polarization beam splitter 43 and reaches the R reflective liquid crystal display element 33R. The B color light incident on the second polarization beam splitter 43 as S-polarized light reflects the polarization separation surface of the second polarization beam splitter 43 and reaches the B-use reflective liquid crystal display element 33B.

  The R color light incident on the R reflective liquid crystal display element 33R is image-modulated and reflected. The P-polarized component of the image-modulated R reflected light is transmitted again through the polarization separation surface of the second polarization beam splitter 43, returned to the light source side, and removed from the projection light. On the other hand, the S-polarized light component of the image-modulated R reflected light is reflected from the polarization separation surface of the second polarizing beam splitter 43 and directed to the half-wave plate 44 as projection light and converted to P-polarized light.

  The B color light incident on the B reflective liquid crystal display element 33B is image-modulated and reflected. Of the image-modulated B reflected light, the S-polarized light component is again reflected on the polarization separation surface of the second polarization beam splitter 43, returned to the light source side, and removed from the projection light. On the other hand, the P-polarized component of the image-modulated B reflected light is reflected by the polarization separation surface of the second polarizing beam splitter 43 and is directed to the half-wave plate 44 as projection light and converted to S-polarized light.

  At this time, by adjusting the slow axis of the quarter wave plates 32R and 32B provided between the second polarizing beam splitter 43 and the reflective liquid crystal display elements 33R and 33B for R and B, G As in the case of, the black display of R and B can be adjusted.

  In this way, the R and B color lights combined into one light beam and emitted from the second polarization beam splitter 43 are incident on the synthesis prism 35 as R color light P-polarized light and B color light S-polarized light.

  The R and B projection light passes through the combining prism 35 and is combined with the G color light to reach the projection lens 36. The projection lens 36 is a projection unit (projection optical system) that projects the light synthesized by the synthesis prism 35 onto a projection surface (not shown). The combined R, G, and B projection light is enlarged and projected onto a projection surface such as a screen by the projection lens 36.

  The color separation optical elements (for example, the dichroic mirror 29, the first polarization beam splitter 31, and the second polarization beam splitter 43) are disposed between the condenser lens system and the display element. For this reason, the principal ray incident on each angle of view of the display element is configured to be incident on the color separation optical element at substantially the same angle. Therefore, the angle deviation with respect to each angle of view by adjusting the illumination range is small, and color unevenness in the projected image can be reduced.

  The present invention is not limited to the use of the reflective liquid crystal display elements as in the first and second embodiments, and the same effect can be obtained by using a transmissive liquid crystal display element or DMD (Digital Mirror Device).

  As mentioned above, although the preferable Example of this invention was described, this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary.

  The present invention can be applied to the use of a liquid crystal projector.

6 ... 1st condenser lens (lens group), 8 ... 2nd condenser lens (lens group), 7 ... Mirror (movable mirror), 7a ... Driving means

Claims (6)

There is an illumination optical system that illuminates the image modulation element with light from a light source,
A condensing lens system having two lens groups having positive power, and condensing a light beam from the light source onto the image modulation element;
A mirror that is arranged between the two lens groups of the condenser lens system and adjusts an illumination range for the image modulation element;
Drive means for rotationally driving the mirror;
Have
When the focal length of the condenser lens system is F, and the distance on the optical axis from the surface closest to the image modulation element of the condenser lens system to the image modulation element is Bk, the following conditional expression is satisfied: An illumination optical system.
0.8 ≦ Bk / F <1 The illumination optical system according to claim 1, wherein the following conditional expression is further satisfied.
0.85 ≦ Bk / F <1   The illumination optical system according to claim 1, wherein the driving unit rotationally drives the mirror around an axis perpendicular to a plane including the optical axes of the two lens groups.   3. The driving means rotates the mirror around an axis parallel to a plane including the optical axes of the two lens groups and parallel to a reflecting surface of the mirror. 4. The illumination optical system described in 1.   The illumination optical system according to any one of claims 1 to 3, further comprising a color separation optical element that performs color separation between the condenser lens system and the image modulation element.   A projection display device comprising the illumination optical system according to claim 1.