JP4271150B2 - Projection type display device and method of forming light intensity uniformizing element - Google Patents

Description

  The present invention relates to a projection display apparatus that projects an image on a screen, and more particularly, to a projection display using a reflective light valve such as a digital micromirror device (DMD) or a reflective liquid crystal display element. The present invention relates to a display device.

  As a conventional projection display device, there is a configuration in which a light beam from a light source is guided to a light valve through a light tunnel (cylindrical optical element) (see, for example, Patent Document 1). This light tunnel has a tapered portion formed so that the cross-sectional area continuously decreases on the entrance side, and has a parallel portion formed so that the cross-sectional shape is constant on the exit side. . The cross-sectional shape of the parallel portion and the shape of the emission port are similar to the shape of the light valve (rectangular shape).

Japanese Patent Laying-Open No. 2004-252112 (paragraph 0034, FIG. 2)

  However, for example, when the light beam is not irradiated perpendicularly to the incident surface of the light valve (also referred to as “illuminated surface” or “image forming region”), the cross-sectional shape of the light intensity equalizing element is changed to that of the light valve. Even if the shape of the incident surface is similar, the actual illumination area on the light valve (also referred to as the “real illumination area”) will be different from the incident surface of the light valve. There is a problem that the illumination area is greatly distorted compared to the illumination area. Such a problem is caused by a mirror that guides the light beam to the light valve because, for example, a reflective light valve is used when the light beam cannot enter the light valve perpendicularly to the incident surface of the light valve due to the configuration of the optical system. This often occurs when a projection optical system for enlarging and projecting the light beam reflected by the light valve is disposed adjacently.

  Therefore, the present invention has been made to solve the above-described problems of the prior art, and it is possible to substantially match the shape of the actual illumination area on the reflective light valve with the shape of the ideal illumination area. An object of the present invention is to provide a projection display device capable of improving the light utilization efficiency by a light intensity uniformizing element having a cross-sectional shape that can be formed.

  The projection display device according to the present invention includes a light source, a light intensity uniformizing element for uniformizing an intensity distribution of a light beam emitted from the light source, a reflective light valve having a rectangular image forming area, and the light intensity. A relay optical system for guiding the light beam emitted from the uniformizing element to the reflective light valve; and a projection optical system for enlarging and projecting an image formed in an image forming area of the reflective light valve; The uniformizing element is an optical element having a quadrilateral cross-sectional shape in a direction perpendicular to the central light beam, and each of the rectangular ideal illumination areas determined to include the image forming area on the reflective light valve. In the case where it is assumed that the reference light intensity uniformizing element is used in which the corner portion and the cross-sectional shape in the direction orthogonal to the central light beam are rectangular shapes similar to the image forming region of the reflective light valve. The cross-sectional shape of the light intensity uniformizing element is determined based on the position of each corner of the illumination area on the projecting light bulb and the position of each corner of the cross-sectional shape of the reference light intensity uniformizing element. Is.

  In the present invention, the position of each corner of the ideal illumination area including the image forming area on the reflective light valve and the cross-sectional shape in the direction perpendicular to the central light flux are similar to the image forming area of the reflective light valve. The position of each corner of the illumination area on the reflective light valve when it is assumed that a rectangular reference light intensity uniformizing element is used, and the position of each corner of the cross-sectional shape of the reference light intensity uniformizing element Based on the above, the cross-sectional shape of the light intensity uniformizing element is determined. For this reason, according to the present invention, even if the light beam cannot be irradiated perpendicularly to the image forming area of the reflective light valve, the actual illumination area by the light beam irradiated on the reflective light valve is ideal. It is possible to make it substantially coincide with the illumination area, and the effect that the light use efficiency can be improved is obtained.

  In the present invention, when the shape of the light incident end of the light intensity uniformizing element, the cross-sectional shape of the light intensity uniformizing element, and the shape of the light emitting end of the light intensity uniformizing element are the same shape, Since the cross-sectional shape from the entrance end to the exit end of the light intensity uniformizing element is constant, the manufacturing becomes easy, the manufacturing cost of the light intensity uniformizing element can be reduced, and it is fixedly held in the apparatus. Becomes easier. For this reason, in this case, it is possible to reduce the manufacturing cost of the projection display device.

Embodiment 1 FIG.
FIG. 1 is a diagram schematically showing a configuration of an optical system of a projection display apparatus according to Embodiment 1 of the present invention. FIG. 1 shows the arrangement of each component when the optical system of the projection display device is viewed from above in the actual usage state of the projection display device.

  As shown in FIG. 1, the projection display apparatus according to the first embodiment includes an illumination optical system 1, a DMD element 2 as a reflective light valve, and a DMD element 2 illuminated by the illumination optical system 1. And a projection optical system 3 that projects an image of the illumination surface (image forming region) 2b onto a screen (not shown). The illumination optical system 1 is an optical system for irradiating the illuminated surface 2b of the DMD element 2 with a light beam. The illumination optical system 1 includes a light source lamp 4, a rotating color filter 5 that passes a light beam in a specific wavelength band among the light beams emitted from the light source lamp 4, and a light beam cross section of the light beam that has passed through the rotating color filter 5. A light intensity equalizing element 6 that equalizes the intensity distribution inside (that is, in a plane orthogonal to the central light beam), a relay lens group 7 including lenses 71 to 73, a first mirror 8, and a second mirror 9. have. The relay lens group 7, the first mirror 8, and the second mirror 9 constitute a relay optical system (that is, the constituent members 7, 8, 9) that guides the light beam emitted from the light intensity uniformizing element 6 to the DMD element 2. ing.

  The light source lamp 4 includes, for example, a light emitting body 4a that emits white light and an elliptical mirror 4b provided around the light emitting body 4a. The ellipsoidal mirror 4b reflects the light beam emitted from the first focal point corresponding to the first center of the ellipse and converges it to the second focal point corresponding to the second center of the ellipse. The light emitter 4a is disposed near the first focal point of the ellipsoidal mirror 4b, and the light beam emitted from the light emitter 4a is converged near the second focal point of the ellipsoidal mirror 4b. An illumination optical axis 1a of the illumination optical system 1 is defined by an axis passing through the first focal point and the second focal point of the ellipsoidal mirror 4b. The light source lamp 4 is not limited to the configuration shown in FIG. 1, and a parabolic mirror may be used instead of the ellipsoidal mirror 4b, for example. In this case, the light beam emitted from the light emitter 4a may be made substantially parallel by a parabolic mirror and then converged by a condenser lens (not shown). Further, a concave mirror other than a parabolic mirror can be used instead of the ellipsoidal mirror 4b.

  The rotating color filter 5 is obtained by dividing a disk-shaped member into, for example, a fan shape and forming three filter regions of red, green, and blue, respectively. The three filter regions of red, green, and blue pass only light beams corresponding to the red, green, and blue wavelength bands, respectively. The rotating color filter 5 rotates about an axis 5a that is substantially parallel to the illumination optical axis 1a, and each filter region is positioned on the illumination optical axis 1a of the light source lamp 4 in the vicinity of the second focal point of the ellipsoidal mirror 4b. It is configured as follows. By rotating the rotating color filter 5 in synchronization with the image signal, red light, green light, and blue light are sequentially applied to the DMD element 2 (in a field sequential manner).

  The light intensity uniformizing element 6 equalizes the intensity distribution of the light beam that has passed through the rotating color filter 5 in the cross section of the light beam (that is, in the plane orthogonal to the central light beam that travels on the illumination optical axis 1a) (that is, It has a function to reduce illuminance unevenness. The light intensity uniformizing element 6 is generally made of a transparent material such as glass or resin, and is a quadrangular columnar rod (that is, the cross-sectional shape is a quadrilateral shape) configured such that the inside of the side wall becomes a total reflection surface. Columnar member) or a pipe (tubular member) having a cross-sectional shape of a quadrilateral that is combined in a cylindrical shape with the light reflection surface on the inside. When the light intensity equalizing element 6 is a square columnar rod, the light is reflected from a plurality of times using the total reflection action between the transparent material and the air interface, and then emitted from the exit end (exit port). When the light intensity uniformizing element 6 is a quadrilateral pipe, the light is reflected a plurality of times by using the reflecting action of the surface mirror facing inward, and then emitted from the emission port. If the light intensity equalizing element 6 secures an appropriate length in the traveling direction of the light beam, the light reflected inside the light intensity multiple times is superimposed and irradiated in the vicinity of the exit end 6b of the light intensity equalizing element 6 so that the light intensity is uniform. A substantially uniform intensity distribution is obtained in the vicinity of the emitting end 6 b of the activating element 6. The emission end (also referred to as “light source surface”) 6 b having a substantially uniform intensity distribution is led to the DMD element 2 by the relay lens group 7, the first mirror 8, and the second mirror 9. The illumination surface 2b is illuminated.

  FIG. 2 is a schematic diagram conceptually showing the relationship between the light source image 4 c formed by the light source 4, the light intensity uniformizing element 6, and the DMD element 2. In the first embodiment, the relay lens group 7, the first mirror 8, and the second mirror 9 are configured such that the emission end 6 b of the light intensity uniformizing element 6 and the illuminated surface 2 b of the DMD element 2 are optically conjugate. Configured to be in a relationship. Here, the area of the light source image 4c is S1, the area of the emission end 6b of the light intensity uniformizing element 6 is S3, and the area of the illuminated surface 2b of the DMD element 2 is S2. In FIG. 2, the position of the light source image 4 c and the position of the incident end 6 a of the light intensity equalizing element 6 are depicted so as to be different. The position of the incident end 6a of the intensity uniformizing element 6 is configured to substantially coincide. If the solid angle of the light beam emitted from the light source image 4c is Ω1, the solid angle of the light beam incident on the light intensity uniformizing element 6 is also Ω1, the angle is stored in the light intensity uniformizing element 6, and the angle from the light emitting end 6b. The solid angle of the emitted light beam is also Ω1. On the other hand, when the solid angle of the incident light beam on the illuminated surface 2b of the DMD element 2 is Ω2, the product of each area and the solid angle is kept constant. That is, S1 × Ω1 = S2 × Ω2 is established.

  The DMD element 2 is a planar arrangement of a large number (for example, several hundred thousand) of movable micromirrors corresponding to each pixel, and changes the tilt angle of each micromirror according to pixel information. It is configured as follows. When the surface on which the micromirrors are arranged (that is, the surface of the substrate on which the micromirrors are formed) is used as a reference surface, the DMD element 2 has an angle α (for example, 12) in a certain direction with respect to the reference surface. The incident light beam is reflected toward the projection optical system 3, and the light beam incident on the projection optical system 3 is used for image projection on a screen (not shown). The DMD element 2 also tilts the micromirror in the opposite direction with respect to the reference plane by an angle α, so that the incident light beam is applied to a light absorbing plate (not shown) provided at a position away from the projection optical system 3. The light beam reflected and incident on the light absorbing plate is not used for image projection on the screen.

  The first mirror 8 has a reflecting surface 8b. As shown in FIG. 1, the normal 8a of the reflecting surface 8b of the first mirror 8 is inclined with respect to the optical axis 1a. With such a configuration, the reflecting surface 8 b of the first mirror 8 reflects the light beam incident from the relay lens system 7 toward the second mirror 9. The first mirror 8 has an action of determining the shape of the illumination light beam that irradiates the DMD element 2 and a good irradiation position, and the shape of the first mirror 8 is constituted by a plane mirror or a concave reflection mirror. When the first mirror 8 is configured by a plane mirror, the effect of favorably determining the shape of the illumination light beam that irradiates the DMD element 2 is weakened, but it can be configured at the lowest cost and the thickness of the first mirror 8 is also the largest. Since it can be made thin, it is easy to avoid interference with the DMD element 2 and the second mirror 9. When the reflecting surface of the first mirror 8 is formed of a cylindrical concave surface, it is possible to correct the distortion generated by obliquely irradiating the DMD element 2 and to realize a good illumination light beam shape and irradiation position. Become. Even when the reflecting surface of the first mirror 8 is formed of a concave aspherical surface, the distortion generated by obliquely irradiating the DMD element 2 is corrected well, and a good illumination beam shape and irradiation position are realized. It becomes possible. Further, in the first mirror 8 shown in FIG. 1, the principal ray (that is, the central light beam) emitted from the center of the emission end 6 b of the light intensity uniformizing element 6 reaches the reflection surface 8 b of the first mirror 8. The position is indicated by reference numeral 8c.

  FIG. 3 is a diagram schematically showing the configuration of the projection display apparatus according to the first embodiment when viewed in the direction of the line III-III in FIG. The DMD element 2 is disposed above the illumination optical axis 1a (not shown in FIG. 3) in FIG. The projection optical system 3 includes a lens group (not shown) disposed in a lens barrel 3 c, and the incident side opening 3 b is substantially opposed to the DMD element 2. The projection optical axis 3a of the lens group of the projection optical system 3 is parallel to the normal line 2a passing through the center of the illuminated surface (image display area) 2b of the DMD element 2 and shifted by a predetermined amount δ.

  The second mirror 9 is disposed adjacent to the lower side of the projection optical system 3 in FIG. The second mirror 9 and the lens barrel 3c of the projection optical system 3 are arranged as close as possible within a range where they do not interfere with each other. The light beam reflected by the reflecting surface 9 b of the second mirror 9 is incident on the illuminated surface 2 b of the DMD element 2, reflected by the illuminated surface 2 b of the DMD element 2, and incident on the incident opening 3 b of the projection optical system 3. To do. The reflection surface 9b of the second mirror 9 is constituted by, for example, a concave spherical surface or an elliptical reflection surface. When the reflecting surface of the second mirror 9 is an elliptical reflecting surface, the effect of improving the light utilization efficiency is high.

  As shown in FIG. 1, the traveling direction of the light beam from the DMD element 2 to the projection optical system 3 is a top view with respect to the traveling direction of the light beam from the light source lamp 4 to the first mirror 8 (that is, FIG. 1). In) are substantially orthogonal. Further, the normal 2a of the illumination target surface 2b of the DMD element 2 and the projection optical axis 3a of the projection optical system 3 are both substantially orthogonal to the illumination optical axis 1a in a top view. The reason for this arrangement is that, first, when the relationship between the normal 2a of the illuminated surface 2b of the DMD element 2 and the projection optical axis 3a of the projection optical system 3 deviates greatly from the substantially orthogonal relationship, It is difficult to dispose these components without blocking the light paths of the light source lamp 4, the relay lens group 7, the first mirror 8, the second mirror 9, the reflective light valve 2, and the projection optical system 3. Because it becomes. Second, the tilt angle of the light source lamp 4 is permitted to be used up to about 15 degrees. However, as the tilt angle increases, the brightness decreases and the flicker phenomenon of the light source lamp 4 occurs. This is because it is difficult to obtain a good image. For these reasons, as shown in FIG. 1, the angle of intersection γ between the illumination optical axis 1a of the illumination optical system 1 and the normal 2a of the illuminated surface 2b of the DMD element 2 (with the illumination optical axis 1a of the illumination optical system 1). The angle of intersection of the projection optical system 3 and the projection optical axis 3a is preferably 90 ± 5 degrees.

  Next, a method for determining the cross-sectional shape of the light intensity uniformizing element 6 in the first embodiment (which is also the emission end shape in the first embodiment) will be described.

  FIG. 4 shows an illuminated surface 2b on the DMD element 2 and a light intensity equalizing element having a cross-sectional shape similar to the illuminated surface of the DMD element (in this application, “reference light intensity equalizing element”). FIG. 5 is a diagram schematically showing the actual illumination region 2c ′ on the DMD element 2 when FIG. 5 is used, and FIG. 5 shows the illuminated surface 2b on the DMD element 2 and the ideal illumination region 2d. It is a figure shown roughly. FIG. 6A is a diagram showing an actual illumination region 2c ′ on the DMD element 2 when the reference light intensity uniformizing element is used, and FIG. It is a figure which shows roughly the cross-sectional shape 6c 'of an element. Further, FIG. 7 schematically shows an illuminated surface 2b on the DMD element 2, an ideal illumination area 2d, and an actual illumination area 2c 'on the DMD element 2 when a reference light intensity uniformizing element is used. FIG. 8 schematically shows a cross-sectional shape 6d ′ of the reference light intensity uniformizing element and a cross-sectional shape (also an end shape) 6e of the light intensity uniformizing element 6 in the first embodiment. FIG. Furthermore, FIG. 9 shows an actual illumination area 2f on the DMD element 2 when the illuminated surface 2b on the DMD element 2, the ideal illumination area 2d, and the light intensity equalizing element 6 in the first embodiment are used. FIG. 10 is an external perspective view schematically showing the shape of the light intensity uniformizing element 6 in the first embodiment.

  In a general illumination optical system (an illumination optical system corresponding to the illumination optical system 1 in FIG. 1), the cross-sectional shape 6c ′ of the light intensity uniformizing element (reference light intensity uniformizing element) (FIG. 6B). Is constant from the incident end (incident end corresponding to the incident end 6a in FIG. 1) to the outgoing end (outgoing end corresponding to the outgoing end 6b in FIG. 1), and the surface to be illuminated 2b of the DMD element 2 It is formed in a rectangle that is a similar shape. Further, in the illumination optical system 1 using the DMD element 2, as shown in FIG. 1, the normal direction perpendicular to the illuminated surface 2b of the DMD element 2 from the second mirror 9 (in FIGS. 1 and 3). Since the irradiation is performed from an oblique direction inclined with respect to the axis 2a direction), even if the design of the illumination optical system 1 is devised, the actual illumination area (actual illumination area) on the illuminated surface 2b of the DMD element 2 is distorted. It often happens.

  For example, an example in which an optical system is designed with a configuration as shown in Table 1 (an example using a reference light intensity uniformizing element whose cross-sectional shape is a rectangle that is similar to the illuminated surface of the DMD element. (Referred to as “reference example”).

  In the reference example, as shown in Table 1, a cross-sectional shape 6c ′ (shown in FIG. 6B) of a reference light intensity uniformizing element (an element corresponding to the light intensity uniformizing element 6 in FIG. 1). The DMD element 2 is formed in a rectangular shape similar to the shape of the illuminated surface 2b. The relay lens group 7 is composed of three spherical lenses, the first mirror 8 is composed of a plane mirror, and the second mirror 9 is composed of a concave spherical mirror. The size of the illuminated surface 2b of the DMD element 2 is 10.51 mm in length and 14.01 mm in width.

  As shown in FIG. 4, the actual illumination area 2 c ′ on the DMD element 2 in the reference example using the reference light intensity uniformizing element is distorted as compared to the shape (rectangular shape) of the illuminated surface 2 b of the DMD element 2. It has a shape. When the actual illumination region 2c ′ is distorted as described above, depending on the product variation of the DMD element, there may be a situation in which the light beam is not irradiated to a portion with a small illumination margin in the actual illumination region 2c ′. In such a case, there is a problem that a portion that is darkened and recognized as a shadow appears on the displayed video screen. Further, there is a problem in that the illumination light beam is wasted in a portion where the illumination margin is large, and the loss of the illumination light beam is large.

  As shown in FIG. 5, the ideal illumination area 2d on the DMD element 2 is, for example, a rectangular area that ensures an illumination margin of a certain width in all directions with respect to the illuminated surface 2b of the DMD element 2. It is. Further, the ideal illumination area 2d is, for example, similar to the illuminated surface 2b of the DMD element 2 (an area obtained by multiplying the illuminated surface 2b of the DMD element 2 by a certain magnification (eg, 1.03 times)). Thus, a rectangular region including the illuminated surface 2b of the DMD element 2 may be used. Furthermore, the ideal illumination region 2d includes, for example, the illuminated surface 2b of the DMD element 2, and a margin of a width WH is secured in the horizontal scanning direction (lateral direction in FIG. 5), and the vertical scanning direction (vertical direction in FIG. 5). ) Can be a rectangular area that secures a margin of width WV (≠ WH). Even if the configuration and design of the illumination optical system 1 are devised to bring the actual illumination area 2c ′ in the reference example (Table 1) using the reference light intensity uniformizing element closer to the ideal illumination area 2d, There is a limit and distortion remains. Therefore, in the first embodiment of the present invention, by optimizing the cross-sectional shape (including the end portion shape) of the light intensity uniformizing element 6, the distortion of the actual illumination region is represented by reference numeral 2f in FIG. We studied to reduce the actual illumination area 2f closer to the ideal illumination area 2d.

  Here, the cross-sectional shape 6e (shown in FIG. 8) of the light intensity uniformizing element 6 in the first embodiment will be described. In FIG. 6A, in the reference example shown in Table 1, points A1 at four corners (four corners) of the actual illumination region 2c ′ when viewed toward the illuminated surface 2b of the DMD element 2 are shown. B1, C1, and D1 are shown. In FIG. 6B, toward the emission end of the reference light intensity uniformizing element corresponding to the points A1, B1, C1, and D1 shown in FIG. The four corners (four corners) A2, B2, C2, D2 of the cross-sectional shape 6c when viewed are shown. The points A1, B1, C1, and D1 of the actual illumination region 2c ′ on the DMD element 2 shown in FIG. 6A are respectively points A2, B2, C2, and the cross-sectional shape 6c ′ of the reference light intensity uniformizing element. Corresponds to D2.

  As described above, in the reference example (Table 1) using the reference light intensity uniformizing element, the actual illumination region 2c ′ on the DMD element 2 has a distorted shape. However, the uniform light intensity in the first embodiment is used. When the optimization element 6 is used, the actual illumination area 2f on the DMD element 2 can be brought close to the ideal illumination area 2d. Below, the cross-sectional shape 6d of the light intensity equalizing element 6 in Embodiment 1 is demonstrated. As shown in FIG. 7, the size of the illuminated surface 2b of the DMD element 2 is 10.51 mm in length and 14.01 mm in width. As an example, a design margin of 3% is set, and the ideal illumination area 2d Is 10.83 mm long and 14.43 mm wide. As shown in FIG. 7, the actual illumination region 2c ′ in the reference example (Table 1) using the reference light intensity uniformizing element has a greatly distorted shape as compared with the ideal illumination region 2d. Table 2 shows a comparison result between the ideal illumination region 2d and the actual illumination region 2c ′ in order to show the degree of distortion of the actual illumination region 2c ′ in the reference example (Table 1) using the reference light intensity uniformizing element.

  7 and Table 2, the x direction indicates the longitudinal direction of the DMD element 2, and the y direction indicates the short direction of the DMD element 2. In the reference example, when the reference light intensity uniformizing element is formed in a rectangular shape having a length of 4.23 mm and a width of 6.08 mm (Table 1), points A2 and B2 at the four corners of the cross-sectional shape of the reference light intensity uniformizing element. , C2, and D2, the positions at which the light rays emitted from the DMD element 2 illuminate the illuminated surface 2b are indicated by points A1, B1, C1, and D1, respectively. Table 2 shows the width (x direction) and height (y direction) of the ideal illumination region 2d in Table 2 (that is, a region where a design margin of 3% is set with respect to the illuminated surface 2b of the DMD element 2). When each is set to 1, relative values in the x direction and the y direction are shown for each of the four corners of the actual illumination region 2c ′.

  In Table 2, the arrival position of the point A1 is 3% larger in the x direction and the same in the y direction than the ideal illumination area 2d, and the arrival position of the point A1 is almost an ideal position. I understand. On the other hand, the arrival position of the point D1 is 54% larger in the x direction and 15% larger in the y direction than the ideal illumination region 2d, and is greatly deviated from the ideal position (that is, the irradiation area becomes considerably large). I understand). Similarly, the point B1 and the point C1 are reaching positions deviating from the ideal illumination region 2d.

  Actually, a method of bringing the distorted actual illumination area 2c ′ shown in FIG. 7 and Table 2 closer to the ideal illumination area 2d will be described. The basic idea is that the four corner points A2, B2, C2, D2 of the light intensity equalizing element 6 corresponding to the four corner points A1, B1, C1, D1 of the actual illumination region 2c ′ of the DMD element 2 are as follows. The light intensity equalizing element 6 is formed in a quadrilateral shape configured to correct the actual illumination region 2c ′ of the DMD element 2.

  FIG. 8 shows a cross-sectional shape 6d ′ of the reference light intensity uniformizing element shown in Table 1 and a cross-sectional shape 6e of the light intensity uniformizing element 6 after correction (that is, in the first embodiment of the present invention). . Cross-sectional shapes 6 d ′ and 6 e in FIG. 8 are views seen toward the emission end 6 b of the light intensity uniformizing element 6.

  The method of determining the cross-sectional shape 6e of the light intensity uniformizing element 6 after correction is theoretically the distortion of the actual illumination region 2c 'of the DMD element 2 when irradiated with the cross-sectional shape 6d' of the reference light intensity uniformizing element. The shape may be offset. Table 3 shows the cross-sectional shape 6e of the light intensity uniformizing element 6 that cancels out the distortion of the actual illumination region 2c 'in the reference example shown in Table 2, with respect to the four corners of the cross-sectional shape 6d' of the reference light intensity uniformizing element. The ratio when the point is 1 indicates the correction position when the longitudinal direction of the light intensity uniformizing element 6 is the x direction and the short direction is the y direction as in Table 2.

  In actual design, it is desirable to determine the cross-sectional shape 6e of the light intensity uniformizing element 6 in consideration of the performance of the illumination optical system 1 and the performance of the projection optical system 3. For example, it is desirable to determine the theoretical corrected cross-sectional shape 6e shown in Table 3 with a slight margin in each direction. Table 3 shows a cross-sectional shape 6f after correction of the final light intensity uniformizing element 6 in the design example of the first embodiment. FIG. 9 shows an illumination region 2f of the DMD element 2 when irradiated with the light intensity uniformizing element 6 having the corrected cross-sectional shape 6f.

  In FIG. 9, when the DMD element 2 is irradiated with the light intensity uniformizing element 6 having the corrected cross-sectional shape 6f, the illumination region 2f (when the DMD element 2 is irradiated with the light intensity uniformizing element 6 having the cross-sectional shape 6e) Is substantially the same shape as the illumination area 2), which is quite close to the ideal illumination area 2d. The shape of the light intensity equalizing element 6 in this case is shown in FIG. The light intensity uniformizing element 6 is formed from a constant quadrilateral shape with a cross-sectional shape of 6f from the incident end 6a to the outgoing end 6b. The area of the cross-sectional shape 6f is substantially equal to the area of the original cross-sectional shape 6d, and the relationship of S1 × Ω1 = S2 × Ω2 is maintained.

  In the first embodiment, since the light intensity uniformizing element 6 as shown in FIG. 10 is used, a reference light intensity uniformizing element having a rectangular cross section similar to the illuminated surface of the DMD element is used. Compared with the case where the illumination area 6f of the DMD element 2 is formed, the illumination area 6f of the DMD element 2 has a shape close to the ideal illumination area 6c that secures a constant design margin in all directions with respect to the illuminated surface 6b. The problem that a part of the screen becomes dark will not occur.

  Specifically, in the first embodiment, it has been confirmed that the light utilization efficiency is improved by about 10% in comparison with the case where the reference light intensity uniformizing element is employed.

  In the first embodiment, the traveling direction of the light beam from the light intensity uniformizing element 6 to the first mirror 8 and the traveling direction of the light beam from the reflective light valve 2 to the incident side opening 3b of the projection optical system 3 are as follows. Therefore, it is easy to lay out, and it is possible to suppress the occurrence of defects of the light source lamp 4 and obtain a good image.

  Furthermore, in Embodiment 1, each pixel of the reflective light valve 2 is configured by a movable micromirror that can change the tilt angle of the reflection angle, so that the intensity distribution in the cross section of the illumination light beam is made uniform, and uneven illuminance is reduced. It becomes possible to suppress.

  Furthermore, in the first embodiment, when the light intensity uniformizing element 6 is configured by a tubular member so as to reflect the light beam on its inner surface, the element itself is less likely to be heated by the illumination light beam, and the light intensity is uniformized. The cooling and holding of the element 6 is simplified.

  In the first embodiment, since the light intensity uniformizing element 6 is made of a quadrangular columnar member made of a transparent material, the light intensity uniformizing element 6 can be easily designed.

Embodiment 2
FIG. 11 is a diagram showing a surface to be illuminated on the DMD element and an ideal illumination area on the Cartesian coordinate system with the central light flux as the origin in the second embodiment of the present invention, and FIG. 12 shows the embodiment. 2 is a diagram showing an ideal illumination area on the DMD element in FIG. 2 and an actual illumination area on the DMD element in the case where the reference light intensity uniformizing element is used, on an orthogonal coordinate system with the central light beam as the origin. FIG. 13 is a diagram showing the cross-sectional shape of the reference light intensity uniformizing element on an orthogonal coordinate system with the central light beam as the origin, and FIG. 14 shows the cross-sectional shape of the reference light intensity uniformizing element and the implementation. It is a figure which shows the cross-sectional shape of the light intensity equalization element in the form 2 on the orthogonal coordinate system which makes a center light beam the origin.

  The projection display device according to the second embodiment is different from the projection display device according to the first embodiment in the method of determining the cross-sectional shape (including the end shape) of the light intensity uniformizing element 6. Since the other points are the same as those in the first embodiment, FIG. 1 is also referred to in the description of the second embodiment.

In the second embodiment, as shown in FIGS. 11 to 14, horizontal scanning of the illuminated surface (image forming area) 2b of the DMD element 2 is performed with the center light beam position as the origin in a plane orthogonal to the center light beam. A coordinate system in which the x-axis and the y-axis are placed in each of the direction and the vertical scanning direction is used. In such a coordinate system, the coordinates of the corners of the ideal illumination region 2d on the DMD element 2 are (−Xa1, Ya1), (Xb1, Yb1), (−Xc1, −Yc1), (Xd1, − Yd1), and the coordinates of the corners of the actual illumination region 2c ′ on the DMD element 2 on the assumption that the reference light intensity uniformizing element is used are (−Xa2, Ya2), (Xb2, Yb2), ( -Xc2, -Yc2), (Xd2, -Yd2), and the coordinates of the corners of the cross-sectional shape 6d 'of the reference light intensity uniformizing element are (-Xa3, Ya3), (Xb3, Yb3), (- Xc3, -Yc3), (Xd3, -Yd3), and the coordinates of the corners of the cross-sectional shape 6e of the light intensity uniformizing element 6 in the second embodiment are (-Xa4, Ya4), (Xb4, Yb4), (-Xc4,- Yc4) and (Xd4, -Yd4). In the projection display device according to Embodiment 2, the cross-sectional shape 6e of the light intensity uniformizing element 6 is determined so as to satisfy the following conditional expressions 1 to 8.
0.9 × (Xa1 / Xa2) <Xa4 / Xa3 <1.2 × (Xa1 / Xa2) Formula 1
0.9 × (Xb1 / Xb2) <Xb4 / Xb3 <1.2 × (Xb1 / Xb2) Equation 2
0.9 × (Xc1 / Xc2) <Xc4 / Xc3 <1.2 × (Xc1 / Xc2) Equation 3
0.9 × (Xd1 / Xd2) <Xd4 / Xd3 <1.2 × (Xd1 / Xd2) Equation 4
0.9 × (Ya1 / Ya2) <Ya4 / Ya3 <1.2 × (Ya1 / Ya2) Equation 5
0.9 × (Yb1 / Yb2) <Yb4 / Yb3 <1.2 × (Yb1 / Yb2) Equation 6
0.9 × (Yc1 / Yc2) <Yc4 / Yc3 <1.2 × (Yc1 / Yc2) Equation 7
0.9 × (Yd1 / Yd2) <Yd4 / Yd3 <1.2 × (Yd1 / Yd2) Equation 8

  If the ratio of the cross-sectional shape size of the light intensity uniformizing element of the second embodiment to the size of the cross-sectional shape of the reference light intensity uniformizing element becomes smaller than the lower limit value in the conditional expressions 1 to 8, the actual condition on the DMD element 2 The illumination area becomes smaller, and a phenomenon in which a part of the projection screen becomes dark tends to occur. Further, when the ratio of the cross-sectional shape size of the light intensity uniformizing element of Embodiment 2 to the cross-sectional size size of the reference light intensity uniformizing element becomes larger than the upper limit value in the conditional expressions 1 to 8, it is used for image projection. The light flux that is not increased increases, and the light utilization efficiency is greatly reduced.

Theoretically, it is further desirable that the following conditional expressions 9 to 16 are substantially satisfied (that is, the conditional expressions indicated by an equal sign in the conditional expressions 9 to 16 are substantially satisfied).
Xa4 / Xa3 = Xa1 / Xa2 Formula 9
Xb4 / Xb3 = Xb1 / Xb2 Formula 10
Xc4 / Xc3 = Xc1 / Xc2 Equation 11
Xd4 / Xd3 = Xd1 / Xd2 Equation 12
Ya4 / Ya3 = Ya1 / Ya2 Formula 13
Yb4 / Yb3 = Yb1 / Yb2 Formula 14
Yc4 / Yc3 = Yc1 / Yc2 Formula 15
Yd4 / Yd3 = Yd1 / Yd2 Equation 16

  According to the projection display apparatus of the second embodiment, even when the light beam cannot be irradiated perpendicularly to the image forming area 2b of the DMD element 2, the actual illumination area 2f is surely changed to the ideal illumination area 2d. It is possible to make them substantially coincide with each other, and the effect that the light utilization efficiency can be improved is obtained. In the second embodiment, points other than those described above are the same as those in the first embodiment.

Explanation of modification.
In the above description, the expression “up” or “down” is used to indicate the direction in the actual usage state of the projection display device, and the projection display device of the present invention is installed in a posture different from the above description. You can also.

  In the above description, the rotating color filter 5 is disposed between the light source lamp 4 and the light intensity uniformizing element 6. However, the illumination light beam converges small just after the light intensity uniformizing element 6. If it is a place, it is also possible to arrange in another place.

  Further, in the above description, the case where the DMD element is used as the reflective light valve has been described, but another light valve such as a reflective liquid crystal display element may be used.

It is a figure which shows schematically the structure of the optical system of the projection type display apparatus which concerns on Embodiment 1 of this invention. FIG. 3 is a schematic diagram conceptually showing a relationship between a light source image, a light intensity uniformizing element, and a DMD element in the first embodiment. It is a figure which shows schematically a structure when the projection type display apparatus which concerns on Embodiment 1 is seen in the III-III line direction in FIG. 1 schematically shows an illumination surface on a DMD element and an actual illumination area on the DMD element when a reference light intensity uniformizing element having a rectangular shape similar in cross section to the illumination surface of the DMD element is used. FIG. It is a figure which shows roughly the to-be-illuminated surface and ideal illumination area | region on a DMD element. (A) is a figure which shows the actual illumination area | region on the DMD element at the time of using the reference light intensity equalization element, (b) shows roughly the cross-sectional shape of the reference light intensity equalization element. FIG. It is a figure which shows roughly the to-be-illuminated surface on a DMD element, an ideal illumination area | region, and the actual illumination area | region on a DMD element in the case of using the reference | standard light intensity equalization element. It is a figure which shows roughly the cross-sectional shape of the reference | standard light intensity equalization element, and the cross-sectional shape of the light intensity equalization element in Embodiment 1. FIG. It is a figure which shows roughly the to-be-illuminated surface on a DMD element, an ideal illumination area | region, and the actual illumination area | region on a DMD element at the time of using the light intensity equalization element in Embodiment 1. FIG. 3 is an external perspective view schematically showing the shape of the light intensity uniformizing element in the first embodiment. It is a figure which shows the to-be-illuminated surface on the DMD element in Embodiment 2 of this invention, and an ideal illumination area | region on the orthogonal coordinate system which makes a center light beam the origin. FIG. 5 is a diagram showing an ideal illumination area on the DMD element in Embodiment 2 and an actual illumination area on the DMD element when a reference light intensity uniformizing element is used on an orthogonal coordinate system with the center light flux as the origin. is there. It is a figure which shows the cross-sectional shape of the reference | standard light intensity equalization element on the orthogonal coordinate system which makes a center light beam the origin. It is a figure which shows the cross-sectional shape of the reference | standard light intensity equalization element, and the cross-sectional shape of the light intensity equalization element in Embodiment 2 on the orthogonal coordinate system which makes a center light beam the origin.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Illumination optical system, 2 DMD element, 2b The to-be-illuminated surface of DMD element, 2c 'real illumination area | region at the time of using the light intensity equalization element for a reference | standard, 2d ideal illumination area, 2f real illumination area, 3 projection optical system , 4 lamp, 5 rotating color filter, 6 light intensity uniformizing element, 6a incident end, 6b exit end, 6d ′ cross sectional shape of reference light intensity uniformizing element, relay lens group, 8 first mirror, 9 second mirror .

Claims (11)

A light source;
A light intensity uniformizing element for uniformizing the intensity distribution of the light beam emitted from the light source;
A reflective light valve having a rectangular image forming area;
A relay optical system for guiding a light beam emitted from the light intensity uniformizing element to the reflective light valve;
A projection optical system for enlarging and projecting an image formed in the image forming area of the reflective light valve;
The light intensity uniformizing element is an optical element having a quadrilateral cross-sectional shape in a direction perpendicular to the central light beam,
The position of each corner of the rectangular ideal illumination area determined to include the image forming area on the reflective light valve and the cross-sectional shape in the direction perpendicular to the central light beam form the image of the reflective light valve. The position of each corner of the illumination area on the reflective light valve and the cross-sectional shape of the reference light intensity uniformizing element when it is assumed that a reference light intensity uniformizing element having a rectangular shape similar to the area is used A projection type display device, wherein the cross-sectional shape of the light intensity uniformizing element is determined based on the position of each corner. In a coordinate system in which the center beam position is the origin in the plane orthogonal to the center beam, and the x-axis and y-axis are respectively set in the horizontal scanning direction and the vertical scanning direction of the image forming area of the reflective light valve,
The coordinates of the corners of the ideal illumination area on the reflective light valve are (−Xa1, Ya1), (Xb1, Yb1), (−Xc1, −Yc1), (Xd1, −Yd1), respectively.
When it is assumed that the reference light intensity uniformizing element is used, the coordinates of the corners of the illumination area on the reflective light valve are (−Xa2, Ya2), (Xb2, Yb2), (−Xc2, − Yc2), (Xd2, -Yd2),
The coordinates of the corners of the cross-sectional shape of the reference light intensity uniformizing element are (−Xa3, Ya3), (Xb3, Yb3), (−Xc3, −Yc3), and (Xd3, −Yd3), respectively.
When the coordinates of the corners of the cross-sectional shape of the light intensity uniformizing element are (−Xa4, Ya4), (Xb4, Yb4), (−Xc4, −Yc4), (Xd4, −Yd4),
0.9 × (Xa1 / Xa2) <Xa4 / Xa3 <1.2 × (Xa1 / Xa2) Formula 1
0.9 × (Xb1 / Xb2) <Xb4 / Xb3 <1.2 × (Xb1 / Xb2) Equation 2
0.9 × (Xc1 / Xc2) <Xc4 / Xc3 <1.2 × (Xc1 / Xc2) Equation 3
0.9 × (Xd1 / Xd2) <Xd4 / Xd3 <1.2 × (Xd1 / Xd2) Equation 4
0.9 × (Ya1 / Ya2) <Ya4 / Ya3 <1.2 × (Ya1 / Ya2) Equation 5
0.9 × (Yb1 / Yb2) <Yb4 / Yb3 <1.2 × (Yb1 / Yb2) Equation 6
0.9 × (Yc1 / Yc2) <Yc4 / Yc3 <1.2 × (Yc1 / Yc2) Equation 7
0.9 × (Yd1 / Yd2) <Yd4 / Yd3 <1.2 × (Yd1 / Yd2) Equation 8
The projection display device according to claim 1, wherein: Xa4 / Xa3 = Xa1 / Xa2 Formula 9
Xb4 / Xb3 = Xb1 / Xb2 Formula 10
Xc4 / Xc3 = Xc1 / Xc2 Equation 11
Xd4 / Xd3 = Xd1 / Xd2 Equation 12
Ya4 / Ya3 = Ya1 / Ya2 Formula 13
Yb4 / Yb3 = Yb1 / Yb2 Formula 14
Yc4 / Yc3 = Yc1 / Yc2 Formula 15
Yd4 / Yd3 = Yd1 / Yd2 Equation 16
The projection display device according to claim 2, further satisfying:   The shape of the light incident end of the light intensity uniformizing element, the cross-sectional shape of the light intensity uniformizing element, and the shape of the light emitting end of the light intensity uniformizing element are the same shape. Item 4. The projection display device according to any one of Items 1 to 3.   5. The center light beam of the light beam traveling from the relay optical system toward the reflective light valve is inclined with respect to the normal line of the image forming area of the reflective light valve. 6. The projection display device described in 1.   The center light beam of the light beam directed from the image forming area of the reflective light valve to the projection optical system is inclined with respect to the normal line of the image forming area of the reflective light valve. 6. The projection display device according to any one of 5 above. The relay optical system is
A first mirror that reflects the light beam emitted from the light intensity uniformizing element;
The projection according to claim 1, further comprising: a second mirror that is adjacent to the projection optical system and reflects a reflected light beam from the first mirror toward the reflective light valve. Type display device.   The central light beam of the light beam directed from the light intensity uniformizing element to the first mirror and the central light beam of the light beam directed from the second mirror to the image forming area of the reflective light valve are substantially orthogonal to each other. The projection display device according to claim 7.   9. The projection display device according to claim 1, wherein the reflection type light valve includes a plurality of movable micromirrors capable of changing an inclination angle of a reflection surface.   The light intensity equalizing element has a quadrilateral cross-sectional shape configured such that the inner surface of the light-reflecting surface is a quadrilateral tubular member, or a transparent material and the side wall inside is a total reflection surface. The projection display device according to claim 1, wherein the projection display device is any one of columnar members. A light source, a light intensity uniformizing element for uniformizing the intensity distribution of the light beam emitted from the light source, a reflective light valve having a rectangular image forming area, and a light beam emitted from the light intensity uniformizing element. A cross-sectional shape in a direction perpendicular to the central light beam in a projection display device having a relay optical system leading to a reflective light valve and a projection optical system for enlarging and projecting an image formed in an image forming area of the reflective light valve A method of forming the light intensity uniformizing element having a quadrilateral shape,
Determining the position of each corner of a rectangular ideal illumination area to ensure a margin in all directions relative to the image formation area so as to include the image formation area on the reflective light valve;
Each of the actual illumination areas on the reflective light valve in the case of using a reference light intensity equalizing element whose cross-sectional shape in a direction perpendicular to the central light beam is a rectangle similar in shape to the image forming area of the reflective light valve Find the corner position,
The obtained position of each corner of the ideal illumination area, the position of each corner of the obtained actual illumination area, and the position of each corner of the cross-sectional shape of the reference light intensity equalizing element Based on this, the cross-sectional shape of the light intensity uniformizing element is determined.
A method for forming a light intensity uniformizing element.

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