JP2006189538A - Illuminating optical system and projection type display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illuminating optical system and a projection type display device that can be downsized and reduced in imaging magnification. <P>SOLUTION: The optical system of the illuminating optical system 1B composing the projection type lighting system has, along its optical system, a first relay lens 3, a second relay lens 4 and a field lens 5 with a diaphragm function. The lens back face 4b of the second relay lens 4 is formed as a mirror face. A luminous flux emitted from a light source section is made incident on the lens surface 4a of the second relay lens 3 after transmitted through a rod integrator 2 and the first relay lens 3. Then, it is reflected from the lens back face 4b and emitted from the lens surface 4a. A luminous flux emitted from the second relay lens 4 is made incident on the surface of a DMD section 6 after transmitted through the field lens 5. Since the lens back face 4b of the second relay lens is a reflecting face, an optical path between the second relay lens 4 and the field lens 5 can be shortened. This constitution makes it possible to downsize the illuminating optical system 1B and projection type lighting system despite the reduction in imaging magnification. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an illumination optical system, and more particularly to a projection display device using the illumination optical system.

  Currently, a digital light processing (registered trademark) method (hereinafter referred to as “DLP method”) projector using a digital micro mirror device (hereinafter referred to as DMD), which is a reflective display element, has become widespread. An illumination optical system using a field lens is used in a projection display device (projector) of a single plate type DLP system which is the most compact type among DLP systems.

  FIG. 10 shows a conventional single-plate DLP projection display apparatus and a conventional illumination optical system using a field lens used in a conventional projection display apparatus. A conventional projection display device 100A includes a light source unit 101 in which a lamp made of an ultrahigh pressure mercury lamp or the like that emits white light is disposed at one focal point of an elliptical reflector 102, an illumination optical system 100B, and an image on a screen in an enlarged manner. Projecting lens 109. The illumination optical system 100B is arranged in the vicinity of the light exiting surface of the integrator unit 103 and the integrator unit 103 that takes in a light beam emitted from the light source unit 101 and reduces unevenness of illumination on the exit surface, and emits white light from the light source unit. The first relay as a first lens unit of a color wheel 104 that is time-divided into three primary colors, red, blue, and green, and a relay lens unit that is designed so that the exit surface and the imaging surface of the integrator unit 103 are conjugate. The lens unit 105a, the second relay lens unit 105b as the second lens unit, the mirror unit 106 that changes the traveling direction of the light beam, and a part of the relay lens unit, the first relay lens unit 105a and the second relay lens A DMD unit serving as a reflective display element unit emits a light beam incident from the unit 105b in parallel with the optical axis (hereinafter referred to as "telecentric"). Controls the amount of main light beam emitted from the projection lens 109 by swinging the angle of a fine micromirror at a high speed with the field lens unit 107 as a third lens unit that converges and emits the light beam incident from 08. DMD unit 108 (see, for example, Non-Patent Document 1). In the illumination optical system 100B shown in FIG. 10, when the magnification of the image formed on the surface of the DMD unit 108 with respect to the image of the exit surface of the integrator unit 103 is the imaging magnification, the result is increased in order to increase the light use efficiency. It has been common to increase the image magnification to the same magnification (usually about 3 times).

On the other hand, in recent years, the panel size of the DMD portion has been reduced due to the improvement of the manufacturing technology of the image display element, and it has become necessary to make the imaging magnification of the illumination optical system smaller (that is, close to the same magnification) as before.
USHIO INC. “Current Status and Trends of Projectors with New Display Devices (Figure 3-32, Figure 3-33)” USHIO Technical Information Magazine Life Edge July 2000 [online] [searched October 22, 2004], Internet, <URL: http://www1.ushio.co.jp/tech/le/le19/19_03_05.html>

However, as shown in the principle diagram of the relationship between the focal length and the imaging magnification in the lens of the optical system in FIG. 11, the three lenses (first lens 111, second lens 112, third lens from the incident side of the luminous flux). 113), an optical system in which the integrator section (not shown in FIG. 11) side and the DMD section (not shown in FIG. 11) side are telecentric (hereinafter referred to as “both side telecentric”). In this case, the distance L ₁ between the first lens 111 and the second lens 112 is approximately equal to the focal length f ₁ of the first lens, and the second lens 112 and the third lens 113 distance L ₂ is arranged to be approximately equal to the focal length f ₃ of the third lens 113. On the surface of the DMD unit (not shown in FIG. 11) that receives the image on the light beam exit surface of the integrator unit (not shown in FIG. 11) that enters the first lens 111 and the light beam emitted from the third lens 113. Assuming that the magnification with the image to be formed is the imaging magnification, the imaging magnification is f ₃ / f ₁ , the imaging magnification is the distance L ₁ between the first lens 111 and the second lens 112, and the second lens 112. And the third lens 113 are close to the ratio L ₂ / L ₁ of the distance L ₂ , the lens is arranged near the center of the optical system when the imaging magnification approaches the same magnification.

In the illumination optical system 100B shown in FIG. 10, a mirror is provided between the second relay lens portion 105b (corresponding to the second lens 112 in FIG. 11) and the field lens portion 107 (corresponding to the third lens 113 in FIG. 11). for providing the part 106, the distance L ₂ becomes longer, the closer to the magnification by reducing the imaging magnification distance L ₁ becomes longer, the illumination optical system 1A of the optical axis of the magnitude apparatus and lengthening a large It will become.

  In recent years, a projection display device using a single-color light emitting diode (hereinafter referred to as LED) of RED (hereinafter referred to as R), GREEN (hereinafter referred to as G), BLUE (hereinafter referred to as B) in the light source section, An illumination optical system using a light beam supplied from a light source unit of an LED has been proposed. However, in general, the brightness of LEDs is inferior to that of ultra-high pressure mercury lamps, etc. Therefore, in order to illuminate the screen with sufficient brightness, the area of the light emitting surface of each LED must be increased, and the light source section is inevitably limited to some extent Size is required. Therefore, even if an LED is used for the light source unit in the projection illumination apparatus 1A and the illumination optical system 1B shown in FIG. 10, the problem that the apparatus becomes large cannot be solved if the imaging magnification is reduced.

  The present invention has been made in view of the above problems, and the object of the present invention is to provide an illumination optical system and a projection display device that can be formed in a small size and can obtain a small imaging magnification. .

  The above-described problems of the present invention include an integrator unit that receives a light beam emitted from a light source unit and emits the light beam with a uniform light amount distribution, and an optical system that guides the light beam emitted from the integrator unit. And an illumination optical system having a reflective display element unit having an irradiation surface that receives the irradiation of the emitted light beam guided by the optical system, wherein the optical system includes a plurality of lens units, and the plurality of lens units At least one lens unit includes a reflecting unit that reflects the light beam incident from the front surface side on the back surface side, and an illumination optical system that is a mirror lens unit that emits the light beam reflected by the reflecting unit from the front surface side Achieved by:

  In addition, by forming one lens portion of the plurality of lens portions forming the illumination optical system with a mirror lens, there is no need to provide a mirror portion separately from the lens portion, and the imaging magnification is reduced. However, the optical path in the optical system can be shortened.

  The above-described problems of the present invention include a light source unit and a mirror lens that reflects a light beam incident from the lens surface to a part of an optical path that guides the light beam emitted from the light source unit, and then emits the light beam from the lens surface. This is achieved by a projection display device having an optical system provided with a portion and a reflective display element portion having an irradiation surface that receives the light beam guided by the optical system.

  By using an illumination optical system using a mirror lens for the projection display device, the optical path of the optical system constituting the projection display device can be shortened while reducing the imaging magnification.

  According to the present invention, it is possible to reduce the size of the illumination optical system itself and obtain a small imaging magnification.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration diagram of a projection display device according to an embodiment of the present invention. The projection display device 1A includes a light source unit 1, an illumination optical system 1B according to the present invention, and a projection lens 7.

  FIG. 2 shows a schematic configuration diagram of a top view and a right side view of the illumination optical system 1B according to the embodiment of the present invention. The illumination optical system 1B includes a rod integrator 2 as an integrator unit, a first relay lens unit 3 as a first lens unit, a second relay lens unit 4 as a second lens unit, and a field as a third lens unit. It has a lens unit 5 and a DMD unit 6 as a reflective display element unit. The first relay lens unit 3, the second relay lens unit 4, and the field lens unit 5 form an optical system in the illumination optical system 1B shown in FIG.

  A light source unit 1 shown in FIG. 1 is an LED light source, and an R LED 9 that emits red (R), which is the three primary colors of light, on three sides of a cube-shaped cross prism 12, and G that emits green (G). The LED 10 is also provided with a B LED 11 that emits blue (B) light.

  FIG. 4 shows an enlarged view of the light source unit 1 shown in FIG. The cross prism 12 of the light source unit 1 includes a first inclined surface 12 a provided from one end of the surface facing the R LED 9 to the other end of the surface facing the B LED 11, and a surface facing the R LED 9. A second inclined surface 12b provided from the other end side to one end side of the surface facing the B LED 11 is provided inside, and an emitting portion 12c is provided on the facing surface of the G LED 10 to emit a light beam to the outside. ing. The first inclined surface 12a is coated with an R-reflecting dielectric multi-layer film that is composed of alternating films of a plurality of dielectrics and reflects light having an R wavelength, and the second inclined surface 12b is coated with a plurality of alternating films of dielectrics. And a B-reflection dielectric multilayer film that reflects light having a wavelength of B is coated.

  As shown in FIGS. 1 and 2, the rod integrator 2 has a structure in which a rectangular columnar cylindrical inner surface is formed as a reflection surface, and an incident surface on which a light beam is incident on one end surface of the light source unit 1 facing the light beam emitting unit 12 c. 2a, and an exit surface 2b for emitting a light beam on the other end surface.

  The first relay lens portion 3 is a convex lens having a convex surface formed by a transparent body such as transparent glass, and is provided in a state in which the optical axis is substantially coincident with the central portion of the exit surface 2 b of the rod integrator 2. . Both surfaces of the first relay lens unit 3 may have the shape of a spherical lens (hereinafter, referred to as “spherical lens”) formed on a curved surface formed by cutting out a part of a sphere, or may be a curved surface other than a spherical surface. The shape of the formed lens (hereinafter referred to as “aspheric lens”) may be used.

  The second relay lens unit 4 has the optical axis direction of the lens surface 4a on the optical axis of the first relay lens unit 3 so that the lens surface 4b substantially coincides with the focal position of the first relay lens unit 3. 1 The relay lens unit 3 and the field lens unit 5 are provided in a state of being directed toward the gap. The second relay lens portion 4 is formed of a transparent body such as transparent glass, the lens surface 4a is formed in a convex curved surface shape, and the lens surface 4b is formed in a concave curved surface shape. The lens surface 4b of the second relay lens unit 4 is formed on a mirror surface on which a metal such as aluminum, chromium or silver is deposited. The second relay lens unit 4 suppresses the aberration because the lens surface 4a is oriented obliquely with respect to the optical axis of the first relay lens unit 3 and the field lens unit 5 and the influence of the aberration tends to appear greatly. It is desirable to have a shape of an aspheric lens that can be formed. The lens surface b has a function of an aperture stop in the optical illumination system 1B according to the present embodiment.

  The field lens unit 5 is provided in a state in which the normal direction of the lens surface that is the optical axis is oriented in a direction perpendicular to the extension lines of the rod integrator 2 and the first relay lens unit 3.

  The field lens unit 5 is formed of a transparent material such as transparent glass, the lens surface 5a is formed in a convex curved surface shape, and the lens back surface 5b is formed in a plane, and is incident from the lens surface 5a or the lens back surface 5b. The converged light flux is converged and emitted from the lens back surface 5b or the lens surface 5a. The lens surface 5a and the lens surface 5b may have a spherical lens shape or an aspheric lens shape.

  The DMD unit 6 is an image display element that reflects an incident light beam in a predetermined direction.

  FIG. 3 is a partially enlarged view showing an outline of a state where the DMD unit 6 is viewed from the side. In FIG. 3, the right side is the front side of the DMD unit 6, and the left side is the back side of the DMD unit 6. The DMD unit 6 is two-dimensionally provided in the number of resolutions required for a 13.7 μm corner or 16.2 μm micromirror that is pivotally supported by a hinge on the surface of a memory semiconductor unit 6 a formed of CMOS or the like. It is arranged in the direction. FIG. 3 shows only two micromirrors 60 and 61 for illustration. When conducting electricity to the CMOS memory semiconductor portion 6a, electrostatic attraction acts between the micromirrors 60 and 61 and the substrate portion 6a, and the micromirrors 60 and 61 each have an angle of ± 12 ° (or ± 10 °) from the horizontal position. Rocks.

  Returning to FIG. 1, the projection lens 7 includes, for example, a plurality of lens groups, a cam cylinder that exerts a cam action on the lens groups to relatively change the distance between the lenses, a motor that rotationally drives the cam cylinder, and the like. It is the structure built in the lens barrel. By changing the distance between the lenses, the focal position of the emitted light beam, the magnification of the image projected on the screen (not shown), and the like can be adjusted.

  The light absorbing plate 8 is provided around the optical path from the DMD unit 6 to the projection lens 7 and is formed of a material that absorbs the light beam incident on the surface.

  The optical action of the projection display device 1A in the present embodiment shown in FIG. 1 and the illumination optical system 1B according to the present embodiment shown in FIG. 2 will be described. 3 and 4 are also used for the description.

  As shown in FIG. 4, the light source unit 1 that forms the projection display device 1A of FIG. 1 reflects the light beam emitted from the R LED 9 by the first inclined surface 12a and proceeds in the direction of the light beam output unit 12c. The light beam emitted from the LED 10 is reflected by the second inclined surface 12b and travels in the direction of the light beam emitting portion 12c, and the light beam emitted from the G LED 11 is transmitted through the first inclined surface 12a and the second inclined surface 12b to emit the light beam. Proceed in the direction of part 12c. A light beam of white light in which RGB light is mixed is emitted from the light beam emitting unit 12 c of the light source unit 1.

  As shown in FIG. 1, the light beam emitted from the light beam emitting portion 12 c of the light source unit 1 enters the incident surface 2 a of the rod integrator 2. The rod integrator 2 reflects the light beam incident from the incident surface 2a a plurality of times on the inner surface. On the exit surface 2b of the lot integrator 2, the luminous flux having a uniform illuminance distribution and uniform illuminance is emitted toward a certain angle range.

  As shown in FIG. 2, the light beam emitted from the emission surface 2 b of the lot integrator 2 enters the first relay lens unit 3. The first relay lens unit 3 refracts the incident off-axis principal ray in the optical axis direction and emits it as a convergent light beam.

  The light beam emitted from the first relay lens unit 3 enters the second relay lens unit 4. The second relay lens unit 4 transmits the light beam incident from the lens surface 4a through the inside of the lens and reflects it to the mirror surface of the lens surface 4b, and transmits the reflected light beam again through the lens surface, and from the lens surface 4a to the field lens unit. The light is emitted as diverging light in five directions.

  The light beam emitted from the second relay lens unit 4 enters the lens surface 5 a of the field lens unit 5. The field lens unit 5 converges off-axis rays incident from the lens surface 5a in the optical axis direction and emits them from the lens back surface 5b. In addition, in order to make the angles of the light beams corresponding to the micromirrors 60 and 61 of the DMD unit 6 substantially uniform and eliminate contrast unevenness on the light beam irradiation surface, the light beams emitted from the lens back surface 5b of the field lens unit 5 are desirably telecentric. .

  The light beam emitted from the lens back surface 5 b of the field lens unit 5 enters the DMD unit 6, and an image of the output surface 2 b of the rod integrator 2 is formed on the micromirrors 60 and 61 provided on the surface of the DMD unit 6. The light beam is reflected.

  As shown in FIG. 3, when the swing angle of micromirrors 60 and 61 provided on the surface of CMOS memory semiconductor portion 6a of DMD portion 6 is +12 degrees (the tilted state of micromirror 60 in FIG. 3), the field The incident light beam incident from the lens unit 5 is regulated by the angle of the micromirror 60 shown in FIG. 3 and reflected in the normal direction, and the reflected light beam is taken into the projection lens 7 shown in FIG. When the swing angle is −12 degrees (the tilted state of the micromirror 61 in FIG. 3), the incident light beam is reflected by being restricted by the angle of the micromirror 61 shown in FIG. It is reflected outside and absorbed by the light absorbing plate 8 shown in FIG.

  Therefore, the amount of light incident on the projection lens 7 is controlled by operating the micromirrors 60 and 61 at high speed and changing the amount of light reflected in the normal direction.

  As shown in FIG. 3, among the light beams reflected by the micromirrors 60 and 61 of the DMD unit 6, the light beam reflected in the normal direction enters the lens back surface 5 b of the field lens unit 5. The field lens unit 5 converges off-axis rays incident from the lens back surface 5b in the direction of the optical axis, emits the light from the lens surface 5a, and enters the projection lens 7 shown in FIG. The light beam incident on the projection lens 7 passes through an internal lens group (not shown) and is emitted to the outside.

  A light beam emitted to the outside from the projection lens 7 shown in FIG. 1 is projected on a screen (not shown). Since the brightness of the image on the screen (not shown) changes depending on the amount of the light beam reflected by the micromirrors 60 and 61 of the DMD unit 6 in the direction of the projection lens 7, gradation expression is possible.

  Here, the curvature radii of the lens surface 4a and the lens surface 4b of the second relay lens unit 4 constituting the illumination optical system 1B according to the present embodiment will be examined.

  In general, in an optical system, a surface including an optical axis and a principal ray is referred to as a meridional surface, and a surface including the principal ray and perpendicular to the meridional surface is referred to as a sagittal surface. The difference in the image formation position between the meridional surface and the sagittal surface is called astigmatism, and one point image is not collected at one point but at two focal points.

  The relationship of the formula (1) is established between the object distance t on the meridional surface and the image distance t ′.

  In addition, the relationship of Expression (2) is established between the object distance s and the image distance s ′ on the sagittal plane.

  In Expressions (1) and (2), I is the incident angle to the curved surface, I ′ is the exit angle from the curved surface, n is the refractive index of the medium between the object surface and the curved surface, and n ′ is the curved surface and the image surface. The refractive index of the medium between is shown. In the formulas (1) and (2), when I = I ′ = 0, the above two formulas are the same formula, so that the sagittal image distance and the meridional image distance are the same, and astigmatism does not occur. .

  Here, in the illumination optical system 1B according to the present embodiment, the second relay lens unit 4 receives a light beam incident from an oblique direction with respect to the optical axis, and reflects the incident light beam in a direction of approximately 90 degrees. Since the structure emits the light beam in an oblique direction, the values of I and I ′ in the expressions (1) and (2) do not become zero. Therefore, astigmatism is likely to occur in an image formed based on the light beam emitted from the second relay lens unit 4. When astigmatism occurs, image blurring occurs, the in-plane illuminance in the image formed becomes non-uniform, and the light utilization efficiency also decreases. It is necessary to reduce the point aberration.

  As described above, in order to reduce astigmatism, it is preferable to make the incident angle and the exit angle with respect to the curved surface of the lens as small as possible.

In the present embodiment, as shown in FIGS. 1 and 2, the incident angle of the light beam is smaller when the radius of curvature R ₁ of the lens surface 4a that is the light beam incident surface of the second relay lens unit 4 is R ₁ > 0. made, also, who curvature radius R ₂ of the rear surface 4b of the mirror deposition is performed in the second relay lens unit 4 also has a R _2> 0 is the incident angle of the light beam becomes small.

  However, the second relay lens unit 4 needs to have a power (hereinafter referred to as “power”) as a positive light condensing power as a whole lens. On the other hand, if the lens surface 4b has a large positive power, a large astigmatism occurs in the second relay lens unit 4.

Therefore, a curvature radius R ₂ of the second lens surface 4b of the relay lens unit 4 is increased, the radius of curvature R ₁ of the second lens surface 4a is the positive power of the relay lens unit 4 is a plane of incidence of the light beam is basically Large astigmatism does not occur.

Thus, R ₂ > R ₁ > 0 (3) between the curvature radius R ₁ and the curvature radius R _2.
It is necessary to establish the relationship.

However, some power may be required for the radius of curvature R ₂ depending on the design. In that case, give the curvature radius R ₂ negative power,
| R ₂ |> R ₁ > 0 (4)
If the radius of curvature R ₁ and the radius of curvature R ₂ are determined so as to satisfy, it is possible to give power to the radius of curvature R ₂ without causing large astigmatism.

Thus, during the curvature radius R ₂ of curvature R ₁ and a lens surface 4b of the second lens surface 4a of the relay lens unit 4 constituting the illumination optical system 1B according to this embodiment, equation (4) It is desirable that this relationship is established.

5 to 7 show the astigmatism and the illuminance distribution of the image plane imaged on the surface portion of the DMD portion 6 when the curvature radius R ₁ and the curvature radius R ₂ are changed with the same focal length. Show.

FIG. 5 is a simulation diagram of the shape of the lens surface 4a and the lens surface 4b and the optical path of the light beam incident on and emitted from the second relay lens unit 4 when the lens surface 4b of the second relay lens unit 4 is formed on the mirror surface. It is. 5A, the lens surface 4a of the second relay lens unit 4 is formed in a convex shape, the lens surface 4b is formed in a flat shape, and the curvature radius R ₁ of the lens surface 4a (hereinafter simply referred to as “R ₁ ”)> FIG. 6 is a simulation diagram of an optical path when 0 and the radius of curvature R ₂ of the lens surface 4b (hereinafter simply referred to as “R ₂ ”) = ∞, that is, R ₂ > R ₁ > 0. FIG. 5B is a simulation diagram of the optical path when the lens surface 4a and the lens surface 4b of the second relay lens unit 4 are formed on a convex lens having the same radius of curvature, and −R ₂ = R ₁ > 0. FIG. 5C is a simulation diagram of the optical path when the rear surface of the second relay lens unit 4 is convex and the lens surface 4a is planar, and R ₁ = ∞ and R ₂ <0. In FIGS. 5A to 5C, the first end surface portion 41 is a schematic view of the surface from which the light beam incident on the second relay lens portion 4 is emitted, and the second end surface portion 42 is the second relay. This is a schematic view of a surface irradiated with a light beam emitted from the lens unit 4. That is, the first end surface portion 41 shown in FIGS. 5-1 to 5-3 corresponds to the emission surface 2b of the rod integrator 2 in FIG. 1, and the second end surface portion 42 shown in FIGS. 1 corresponds to the surface portion of the DMD portion 6 in FIG. Further, the emitted light beam 43 is emitted from the three points on the first end surface portion 41 toward the second relay lens portion 4, and is reflected by the second relay lens portion 4 on the four points on the second end surface portion 42. An incident light beam 44 enters. Since the thickness direction of the second relay lens unit 4 in FIGS. 5-1 to 5-3 (the horizontal direction from FIGS. 5-1 to 5-3) is optimized, the second relay lens unit 4 is optimized. The thickness and the distance between the first end surface portion 41 and the second end surface portion 42 are displayed in different states.

  When comparing FIG. 5A to FIG. 5C, in FIG. 5A, the incident light beam 44 is almost converged at one point on the second end face portion 42, whereas FIG. In FIG. 5C, the incident light beam 44 is not converged to substantially one point on the second end face portion 42 (particularly seen in the third and lowermost incident light beam 44 from the bottom). Therefore, in the simulation results shown in FIG. 5A to FIG. 5C, it can be seen that the state of FIG. 5A hardly causes astigmatism in the second end face portion 42.

FIG. 6 is a simulation diagram illustrating the shapes of the lens surface 4a and the lens surface 4b and the image formation positions of the meridional surface and the sagittal surface when the lens surface 4b of the second relay lens unit 4 is formed as a mirror surface. . FIG. 6A is a simulation diagram illustrating the image formation positions of the meridional surface and the sagittal surface when the radius of curvature of the second relay lens unit 4 is R ₂ > R ₁ > 0 as in FIG. 6A. FIG. 6B is a simulation diagram showing the imaging positions of the meridional surface and the sagittal surface when the radius of curvature of the second relay lens unit 4 is −R ₂ = R ₁ > 0 as in FIG. 5B. FIG. 6-3 is a simulation showing the image formation positions of the meridional surface and the sagittal surface when the radius of curvature of the second relay lens unit 4 is R ₁ = ∞ and R ₂ <0, as in FIG. 5-3. FIG. In FIGS. 6A to 6C, the x-axis (horizontal axis) parameter represents the distance in the optical axis direction of the second relay lens unit 4, and the y-axis (vertical axis) parameter represents the second relay lens. The distance in the direction perpendicular to the optical axis of the portion 4 is shown. In FIGS. 6A to 6C, if the value of the meridional surface and the value of the sagittal surface coincide with each other, it indicates that astigmatism does not occur in the formed image, and the value of the meridional surface and the sagittal surface If there is a deviation from the surface value, it indicates that the image formed has astigmatism depending on the magnitude of the deviation.

  Comparing FIGS. 6-1 to 6-3, in FIG. 6-1, the curve of the meridional surface and the curve of the sagittal surface have almost the same shape and almost completely overlap, whereas FIG. -2 and 6-3, the meridional surface curve and the sagittal surface curve are shifted depending on the magnitudes of the values in the x-axis direction and the y-axis direction, and the curves are gradually separated from each other. Presents. Accordingly, in the simulation results shown in FIGS. 6A to 6C, it can be seen that the state of FIG. 6A has the least deviation of the luminous flux between the meridional surface and the sagittal surface and the least astigmatism.

7 shows the shape of the lens surface 4a and the lens surface 4b and the in-plane illuminance distribution of the image formed on the surface portion of the DMD portion 6 when the lens surface 4b of the second relay lens portion 4 is formed on the mirror surface. FIG. In FIG. 7, the thick solid line shows the in-plane illuminance distribution of the DMD unit 6 when the second relay lens unit 4 is R ₂ > R ₁ > 0 as in the case of FIGS. 5A and 5B. The dotted line shows the in-plane illuminance distribution of the DMD unit 6 when the second relay lens unit 4 is −R ₂ = R ₁ > 0, as in the case shown in FIGS. Shows the in-plane illuminance distribution of the DMD unit 6 when the second relay lens unit 4 is R ₂ <0 and R ₁ = ∞ as in the cases shown in FIGS. 5-3 and 6-3. In FIG. 7, the horizontal axis indicates a value obtained by normalizing the distance from the reference point (substantially central portion of the DMD unit 6 to which the light beam is irradiated) between −1 <x <1, and the vertical axis indicates the DMD unit 6. The value obtained by normalizing the illuminance at 0 <y <1 is shown. The line indicating the in-plane illuminance distribution indicates that the in-plane illuminance distribution is more uniform and the illuminance unevenness does not occur as the rise and fall of the line are closer to the vertical.

In FIG. 7, the curve of the in-plane illuminance distribution in the case of R ₂ > R ₁ > 0 shows that when the rising and falling edges are almost vertical and −R ₂ = R ₁ > 0, R ₁ = ∞ and The rise and fall are not vertical in the order of R ₂ <0. According to the simulation results shown in FIG. 7, the in-plane illuminance distribution of the DMD unit 6 is most uniform when the second relay lens unit 4 satisfies R ₂ > R ₁ > 0, that is, when the relationship of the expression (4) is satisfied. It turns out that does not occur.

From the results of FIG. 5 to FIG. 7 also, it is less influenced by astigmatism when the curvature radii R ₁ and R ₂ are determined so that the relationship of the above expression (4) is established in the second relay lens unit 4. In addition, it can be confirmed that the illuminance distribution on the image plane in the surface portion of the DMD portion 6 is improved.

Note that the above formula (4) is a result based only on the optical viewpoint, and in the actual optical illumination system, the above formula (4) may be modified and applied in consideration of factors other than the optical system. For example, when a dichroic mirror is vapor-deposited on the lens surface 4b of the second relay lens unit 4 to form a mirror surface, a flat surface rather than a curve on the vapor-deposited surface causes no problems such as film thickness unevenness. Since a high-quality mirror surface can be formed, R ₂ = ∞ and R ₁ > 0 is optimal for forming a high-quality illumination optical system.

  Here, the relationship between the imaging magnification and the optical path length of the illumination optical system 1B according to the present embodiment will be examined.

  FIG. 8 shows a simulation of the optical path length with respect to the imaging magnification of the illumination optical system 1B according to the present embodiment shown in FIG. 1 and the optical path length with respect to the imaging magnification in the conventional illumination optical system 100B shown in FIG. Results are shown. In FIG. 8, the horizontal axis indicates the imaging magnification, the vertical axis indicates the optical path length, the dotted line graph indicates the simulation result of the conventional illumination optical system 100B, and the solid line graph indicates the illumination optical system 1B according to the present invention. The simulation results are shown. In FIG. 8, both graphs are shown as values obtained by normalizing the optical path length to 1 when the imaging magnification β = 1 of the conventional illumination optical system 100B shown in FIG.

  According to the simulation result of FIG. 8, the illumination optical system 1B according to the present invention has an optical path length shorter than that of the conventional illumination optical system 100B when β ≦ 1.5, when the imaging magnification is β. Therefore, it can be seen that the size of the illumination optical system 1B according to the present invention can be made smaller than the conventional illumination optical system 100B when the imaging magnification β ≦ 1.5.

  As described above, the illumination optical system 1B according to the present embodiment includes the three lenses of the first relay lens unit 3, the second relay lens unit 4, and the field lens unit 5, of which the second lens on the optical path is the second lens. By using a certain second relay lens unit 4 as a mirror lens unit, the focal length between the lenses can be shortened even when the imaging magnification from the rod integrator 2 to the surface of the DMD unit 6 is low. The device of the mold illumination device 1A and the illumination optical system 1B can be formed in a small size.

In the illumination optical system 1B according to this embodiment, the radius of curvature of the second lens surface 4a of the relay lens unit 4 and R _1, when the radius of curvature of the lens surface 4b was _{R 2, | R 2 |>} R By setting ₁ > 0, it is possible to prevent the generation of astigmatism, the generation of luminance unevenness and contrast unevenness, and the generation of uneven illumination on the light beam irradiation surface such as the surface of the DMD unit 6 or the screen. it can. Also, by setting | R ₂ |> R ₁ > 0, the imaging performance can be improved even with a small number of lenses, which is advantageous for downsizing the illumination optical system 1B and the projection illumination device 1A. become.

  In the illumination optical system 1B according to the present embodiment, by setting the imaging magnification β to β ≦ 1.5, the optical path length of the illumination optical system 1B can be formed shorter than that of the conventional illumination optical system 100B. The size of the optical system 1B and the projection illumination device 1A in the optical path length direction can be reduced.

  In the illumination optical system 1B according to the present embodiment, the diaphragm position is provided in the vicinity of the second relay lens unit 4 which is the second lens on the optical path, so that the focal distance between the lenses is shortened, and the illumination optical system. 1B and the projection type illumination device 1A can be formed in a small size.

  In the illumination optical system 1B according to the present embodiment shown in FIG. 1, the lens surfaces 4a of the second relay lens unit 4 are all formed to have the same radius of curvature. However, the present invention is not limited to this and is shown in FIG. As described above, the incident position of the light beam and the emission position of the light beam in the second relay lens unit 4 are completely separated, and the surface shape of the lens surface 4a is changed to the light beam incident surface 4c where the light beam is incident and the light beam output surface where the light beam is emitted. It can also be formed as a compound curved surface having a curvature radius different from 4d.

  As shown in FIG. 9, the effect of suppressing various aberrations such as astigmatism in the second relay lens unit 4 is enhanced by making the curvature radius of the lens surface 4a different between the light beam incident surface 4c and the light beam output surface 4d. Can do. In addition, since the power for condensing light can be freely adjusted as compared with the case where the lens surface has a uniform curvature radius, the material forming the second relay lens portion 4 can have a further selection range.

  In the projection display device 1A according to the present embodiment shown in FIG. 1, a light source using LEDs is used for the light source unit 1, but the present invention is not limited to this, as in the conventional example shown in FIG. An ultra-high pressure mercury lamp that emits white light may be used for the light source unit.

  In the illumination optical system 1B according to the present embodiment shown in FIGS. 1 and 2, the mirror surface of the second lens unit is formed by vapor-depositing metal on the lens back surface 4b of the second relay lens unit 4. The mirror surface does not have to be joined to the second relay lens unit 4, and the mirror surface is provided separately from the second relay lens unit 4, and is incident from the lens surface 4 a of the second relay lens unit 4. The light beam may be emitted from the lens back surface 4b and reflected on the mirror surface.

  In addition, in the illumination optical system 1B according to the present embodiment shown in FIGS. 1 and 2, the RGB color wheel is not provided on the exit surface 2b of the rod integrator 2, but the conventional example shown in FIG. Similarly, a configuration in which a color wheel is provided may be employed. In particular, when white light is used for the light source unit, it is desirable to provide a color wheel as in the conventional example shown in FIG. 2 because the amount of light flux and gradation for each RGB can be easily controlled.

  The present invention is applicable to a projection display device.

1 is a schematic configuration diagram of a projection display device according to an embodiment of the present invention. It is the structure schematic of the top view and right view of the illumination optical system which concerns on one embodiment of this invention. It is the elements on larger scale which show the outline of DMD part of an illumination optical system same as the above. It is an enlarged view of the light source part of the projection type display apparatus which concerns on one embodiment of this invention. In the illumination optical system according to an embodiment of the present invention, the lens surface of the second relay lens unit and the shape of the lens surface, and a simulation diagram of the optical path of the light beam entering and exiting the second relay lens unit. FIG. 6 is a simulation diagram showing the lens surface of the second relay lens unit and the shape of the lens surface and the image formation positions of the meridional surface and the sagittal surface in the illumination optical system. FIG. 3 is a simulation diagram showing the lens surface, the shape of the lens surface, and the in-plane illuminance distribution of the image formed on the surface of the DMD part in the illumination optical system. It is a figure which shows the simulation result of the optical path length with respect to the imaging magnification of the illumination optical system which concerns on this invention, and the optical path length with respect to the imaging magnification in the conventional illumination optical system. It is the structure schematic when the 2nd relay lens of the illumination optical system which concerns on this invention is formed in a compound curved surface. It is the structure schematic of the conventional projection type illuminating device and the conventional illumination optical system. It is a principle figure of the relationship between the focal distance and imaging magnification in the lens of an optical system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A ... Projection type display apparatus, 1B ... Illumination optical system, 1 ... Light source part,
2 ... Rod integrator (integrator part), 2b ... Outgoing surface, 3 ... First relay lens (first lens part), 4 ... Second relay lens (second lens part), 4a ..Lens surface, 4b... Lens back surface, 4c... Light beam incident surface, 4d... Light beam exit surface, 5... Field lens part (third lens part), 6. Type display element unit), 7 ... projection lens, 100A ... projection type display device, 1B ... illumination optical system, 101 ... light source unit, 103 ... integrator unit, 105 ... first. Relay lens part (first lens part), 106 ... second relay lens part (second lens part), 107 ... field lens part (third lens part), 108 ... DMD part (reflection display) Element part).

Claims (9)

An optical system provided with a mirror lens unit that reflects the light beam incident from the lens surface to the part of the optical path that guides the light beam emitted from the light source unit, and emits the light from the lens surface;
An illumination optical system, comprising: a reflective display element that receives irradiation of the light beam guided by the optical system. An integrator that emits light with a uniform illuminance distribution of the light emitted from the light source;
An optical system for guiding the light beam emitted from the integrator unit;
A reflective display element that receives irradiation of the light beam guided by the optical system;
In an illumination optical system having
The optical system includes a plurality of lens units, and at least one lens unit of the plurality of lens units includes a reflecting unit that reflects the light beam incident from the lens surface on the lens back surface, and is reflected by the reflecting unit. An illumination optical system comprising a mirror lens portion for emitting the light beam from the lens surface.   The optical system includes a first lens unit, a second lens unit, and a third lens unit in order along an optical path of the light beam emitted from the light source unit, and the second lens unit is the mirror lens unit. The illumination optical system according to claim 1 or 2, characterized in that The radius of curvature at the lens surface and R _1, when the radius of curvature at the lens rear surface and the R _{2, |} R _{2 |>} any one of claims 1, wherein R 1> is ₀ to 3 The illumination optical system according to Item.   5. The imaging magnification, which is the ratio of the illumination size at the surface portion of the reflective display element to the illumination size at the exit surface of the integrator unit, is β ≦ 1.5, where β ≦ 1.5. The illumination optical system according to any one of the above.   The illumination optical system according to claim 1, wherein the third lens unit is a field lens unit having a diaphragm function.   The illumination optical system according to any one of claims 3 to 6, wherein at least one of the lens front surface and the lens back surface of the mirror lens portion is aspherical.   The illumination optical system according to claim 7, wherein the lens front surface and the lens back surface of the mirror lens portion form a complex curved surface having different curvatures. A light source unit;
An optical system provided with a mirror lens unit that reflects the light beam incident from the lens surface to a part of the optical path that guides the light beam emitted from the light source unit and emits the light from the lens surface;
A reflective display element having an irradiation surface that forms an image upon irradiation with the light beam guided by the optical system;
A projection type display device comprising:

Images