Source: https://patents.google.com/patent/US20070139623A1/en
Timestamp: 2020-02-20 00:34:16
Document Index: 40169052

Matched Legal Cases: ['arts 17', 'arts 19', 'arts 17', 'arts 19', 'arts 17', 'arts 17', 'arts 17', 'arts 17', 'arts 17', 'arts 17', 'arts 17', 'art 19', 'art 17', 'arts 17', 'arts 17', 'arts 42', 'arts 44', 'arts 42', 'art 44', 'arts 42', 'arts 25', 'arts 25', 'arts 27', 'arts 25']

US20070139623A1 - Projection display, projection optical system and transmission lens or free curved lens - Google Patents
Projection display, projection optical system and transmission lens or free curved lens Download PDF
US20070139623A1
US20070139623A1 US11/473,087 US47308706A US2007139623A1 US 20070139623 A1 US20070139623 A1 US 20070139623A1 US 47308706 A US47308706 A US 47308706A US 2007139623 A1 US2007139623 A1 US 2007139623A1
US11/473,087
US7670007B2 (en
2005-12-16 Priority to JP2005362594A priority Critical patent/JP4910384B2/en
2005-12-16 Priority to JP2005-362594 priority
2006-06-23 Assigned to HITACHI, LTD. reassignment HITACHI, LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: OHISHI, TETSU, HIRATA, KOJI, OGURA, NAOYUKI, HISADA, TAKANORI, YOSHIKAWA, HIROKI
2007-06-21 Publication of US20070139623A1 publication Critical patent/US20070139623A1/en
2010-03-02 Publication of US7670007B2 publication Critical patent/US7670007B2/en
FIG. 10(a) is a top view of a free curved lens;
FIG. 10(b) is a front elevation of the free curved lens shown in FIG. 10(a);
FIG. 11 is a perspective view of the free curved lens shown in FIG. 10(a);
FIG. 12 is a front elevation of a lens barrel fixedly holding the free curved lens shown in FIG. 10(a);
FIG. 13(a) is a top view of another free curved lens;
FIG. 13(b) is a front elevation of the free curved lens shown in FIG. 13(a);
FIG. 14 is a perspective view of the free curved lens shown in FIG. 13(a);
FIG. 15(a) is a top view of a free curved lens in a modification of the free curved lens shown in FIG. 10(a);
FIG. 15(b) is a front elevation of a free curved lens in another modification of the free curved lens shown in FIG. 10(a); and
FIG. 16 is a perspective view of the free curved lens shown in FIG. 15(a).
All the lenses of the front lens group 12 of the projection lens 2 have rotationally symmetric refracting surfaces, respectively. The four refracting surfaces of those refracting surfaces are rotationally symmetric a spherical surfaces and the rest are spherical surfaces. Each of the rotationally symmetrical a spherical surface is designated in a local cylindrical coordinate system by the following expression. Z = cr 2 1 + 1 - ( 1 + k ) ⁢ c 2 ⁢ r 2 + A · r 4 + B · r 6 + C · r 8 + D · r 10 + E · r 12 + F · r 14 + G · r 16 + H · r 18 + J · r 20 ( 1 )
A free curved lens included in a rear lens group 13 of the projection lens 2 is designated by the following expression in a local orthogonal coordinate system defined by the x-axis, the y-axis and the z-axis. Z = cr 2 1 + 1 - ( 1 + k ) ⁢ c 2 ⁢ r 2 + ∑ m ⁢ · ∑ n ⁢ ( C ⁡ ( m , n ) · x m · y n ) ( 2 )
where Z is the amount of sag in the free curved surface with respect to a direction perpendicular to the x-axis and the y-axis, c is the curvature of the top, r is distance from the origin in a plane parallel to the xy-plane, k is cone constant and C (m, n) is coefficient. TABLE 1 Surface Rd TH nd νd S0 Infinity 10.00 S1 Infinity 31.34 1.51827 48.0 S2 Infinity 7.06 S3 246.358 4.65 1.85306 17.2 S4 −84.858 18.00 S5 * −83.708 9.00 1.49245 42.9 S6 * −75.314 0.10 S7 41.651 9.32 1.49811 60.9 S8 −42.282 2.50 1.76014 20.0 S9 29.550 0.10 S10 29.476 9.00 1.49811 60.9 S11 −79.153 25.90 S12 Infinity 9.10 S13 −265.353 6.00 1.85306 17.2 S14 −53.869 65.00 S15 −24.898 4.19 1.74702 33.2 S16 −58.225 9.00 S17 * −27.332 10.00 1.49245 42.9 S18 * −32.424 2.50 S19 # Infinity 8.00 1.49245 42.9 S20 # Infinity 20.51 S21 # Infinity 8.00 1.49245 42.9 S22 # Infinity 160.99 S23 # Infinity −400.00 REFL S24 Infinity 305.00 REFL S25 Infinity —
In Table 1, a symbol Rd indicates curvature. The curvature Rd of a curved surface having its center of curvature on the left side in FIG. 3 is positive and on the right side in FIG. 3 is negative. In Table 1, a symbol TH indicates intersurface distance between the respective tops of the adjacent lens surfaces. The intersurface distance TH between a first lens surface and a second lens surface on the left side of the first lens surface in FIG. 3 is positive and the intersurface distance TH between a first lens surface and a second lens surface on the right side of the first lens surface in FIG. 3 is negative. In Table 1, symbols S5, S6, S17 and S18 indicate rotationally symmetric a spherical surfaces, respectively, and asterisk (*) is attached to those symbols to facilitate finding those rotationally symmetric a spherical surfaces. Table 2 shows coefficients for functions defining those rotationally symmetric a spherical surfaces. TABLE 2 Surface Aspheric surface coefficient S5 K −11.7678542 C −1.159E−11 F 2.98642E−20 J −1.255E−26 A −2.7881E−06 D −3.2834E−14 G 1.05201E−21 B 9.67791E−09 E 1.09359E−16 H 1.96001E−24 S6 K −5.4064901 C 2.0324E−12 F 3.0211E−19 J −1.4982E−26 A 6.14967E−07 D −2.2078E−14 G 4.30049E−22 B 4.60362E−09 E −8.0538E−17 H 4.79618E−24 S17 K 1.016429122 C −9.0262E−11 F −1.0521E−18 J −6.0837E−26 A −1.1068E−05 D −1.3984E−13 G −8.1239E−23 B 7.21301E−08 E 3.1153E−16 H 3.86174E−23 S18 K 0.742867686 C −2.2719E−11 F 1.09398E−19 J 9.02232E−29 A 1.51788E−07 D −4.6853E−14 G 1.62146E−22 B 2.10472E−08 E 2.9666E−17 H −3.0801E−25
In Table 1, symbols S19 to S22 indicate the refracting surfaces of the free curved lenses included in the rear lens group 13 of the projection lens 2, respectively, the symbol S23 indicates the reflecting surface of the free curved mirror 5. A sharp (#) is attached to the symbols indicating optical elements having a free curved surface. Table 3 shows coefficients for functions defining the five free curved surfaces. TABLE 3 Surface Free-form surface coefficient S19 C(4, 1) 5.38933E−07 C(2, 5) −1.2381E−09 C(4, 5) −7.4126E−14 K 0 C(2, 3) 8.33432E−07 C(0, 7) 1.13944E−09 C(2, 7) 2.05074E−12 C(2, 0) 0.013500584 C(0, 5) −4.6367E−08 C(8, 0) 3.87771E−12 C(0, 9) −9.2166E−13 C(0, 2) 0.003493312 C(6, 0) −6.2643E−09 C(6, 2) 1.04779E−11 C(10, 0) −2.5867E−15 C(2, 1) −0.00083921 C(4, 2) −2.2449E−08 C(4, 4) 1.80038E−11 C(8, 2) −8.7122E−15 C(0, 3) −0.00032098 C(2, 4) −5.6706E−08 C(2, 6) 5.23019E−11 C(6, 4) 2.85321E−14 C(4, 0) 8.59459E−06 C(0, 6) 9.69952E−10 C(0, 8) 1.69253E−11 C(4, 6) −8.5084E−14 C(2, 2) 2.14814E−06 C(6, 1) −1.1968E−10 C(8, 1) −2.7E−14 C(2, 8) 1.25198E−13 C(0, 4) 7.54355E−06 C(4, 3) −1.3638E−09 C(6, 3) 7.30978E−13 C(0, 10) −5.6277E−14 S20 C(4, 1) 7.49262E−07 C(2, 5) −5.7462E−10 C(4, 5) −3.6141E−13 K 0 C(2, 3) 1.19039E−06 C(0, 7) 1.27396E−09 C(2, 7) 8.54188E−14 C(2, 0) 0.015488689 C(0, 5) −1.2953E−07 C(8, 0) −4.7746E−12 C(0, 9) −5.3469E−13 C(0, 2) 0.006553414 C(6, 0) 5.115E−10 C(6, 2) 7.32855E−12 C(10, 0) 8.92545E−17 C(2, 1) −0.00116756 C(4, 2) −2.1936E−08 C(4, 4) 5.30157E−11 C(8, 2) −5.3434E−15 C(0, 3) −0.00033579 C(2, 4) −5.9543E−08 C(2, 6) 5.05014E−11 C(6, 4) 1.96533E−14 C(4, 0) 7.5015E−06 C(0, 6) 2.03972E−08 C(0, 8) −2.1894E−11 C(4, 6) −1.3923E−13 C(2, 2) −2.5728E−06 C(6, 1) 1.16701E−11 C(8, 1) −1.2515E−13 C(2, 8) 1.06322E−13 C(0, 4) −1.3543E−06 C(4, 3) −1.6198E−09 C(6, 3) 7.64489E−13 C(0, 10) −4.6602E−15 S21 C(4, 1) −1.0379E−07 C(2, 5) 2.81743E−10 C(4, 5) −8.1775E−15 K 0 C(2, 3) 3.0082E−08 C(0, 7) 6.05663E−10 C(2, 7) 3.08022E−14 C(2, 0) 0.015096874 C(0, 5) 7.95521E−08 C(8, 0) 8.39381E−13 C(0, 9) −9.1775E−13 C(0, 2) 0.009982808 C(6, 0) −1.3911E−09 C(6, 2) 1.98531E−12 C(10, 0) −7.8543E−17 C(2, 1) 0.000358347 C(4, 2) 9.33292E−10 C(4, 4) 1.37477E−11 C(8, 2) −8.9588E−16 C(0, 3) 0.000209267 C(2, 4) 3.54468E−09 C(2, 6) −1.0671E−11 C(6, 4) −6.0768E−15 C(4, 0) −3.8593E−07 C(0, 6) 4.1615E−09 C(0, 8) 9.04109E−12 C(4, 6) −1.9528E−14 C(2, 2) −6.8336E−06 C(6, 1) −1.2331E−11 C(8, 1) 2.48401E−14 C(2, 8) 2.6781E−14 C(0, 4) −2.2455E−05 C(4, 3) −2.3367E−10 C(6, 3) 6.92603E−14 C(0, 10) −1.4324E−14 S22 C(4, 1) −3.6973E−07 C(2, 5) 4.8045E−10 C(4, 5) −2.9795E−13 K 0 C(2, 3) −3.0682E−07 C(0, 7) 1.43328E−10 C(2, 7) −2.5306E−14 C(2, 0) 0.022813527 C(0, 5) 4.12093E−08 C(8, 0) −2.0707E−12 C(0, 9) −3.9401E−13 C(0, 2) 0.012060543 C(6, 0) 4.07969E−09 C(6, 2) −4.9221E−12 C(10, 0) 6.88651E−16 C(2, 1) 0.000638931 C(4, 2) 8.5986E−09 C(4, 4) −2.3681E−12 C(8, 2) 1.55006E−15 C(0, 3) 0.000196027 C(2, 4) 2.1713E−08 C(2, 6) −2.1567E−11 C(6, 4) 1.4674E−15 C(4, 0) −7.1204E−06 C(0, 6) 1.63499E−08 C(0, 8) −2.3679E−12 C(4, 6) −9.9822E−15 C(2, 2) −1.269E−05 C(6, 1) 1.38704E−10 C(8, 1) −5.7167E−15 C(2, 8) 2.72925E−14 C(0, 4) −2.5184E−05 C(4, 3) 2.02372E−10 C(6, 3) −9.0337E−14 C(0, 10) −1.1966E−14 S23 C(4, 1) −1.1083E−09 C(2, 5) −4.9118E−14 C(4, 5) −5.4918E−19 K 0 C(2, 3) −5.7768E−10 C(0, 7) 8.12546E−14 C(2, 7) −2.2569E−18 C(2, 0) 0.001597194 C(0, 5) 1.60076E−10 C(8, 0) −7.486E−17 C(0, 9) −3.5657E−18 C(0, 2) 0.001324181 C(6, 0) 1.91534E−12 C(6, 2) 6.80626E−16 C(10, 0) 1.09883E−21 C(2, 1) 1.37885E−05 C(4, 2) −1.0665E−11 C(4, 4) −5.1295E−17 C(8, 2) −2.1535E−20 C(0, 3) 1.34349E−05 C(2, 4) −8.6063E−12 C(2, 6) −3.6526E−16 C(6, 4) 2.01763E−20 C(4, 0) −4.8064E−08 C(0, 6) −1.1125E−12 C(0, 8) 1.46399E−15 C(4, 6) −1.2016E−20 C(2, 2) 5.24071E−08 C(6, 1) 6.24714E−14 C(8, 1) −2.1563E−18 C(2, 8) 3.21408E−21 C(0, 4) 9.53861E−08 C(4, 3) −3.4381E−14 C(6, 3) 2.86073E−18 C(0, 10) −1.4922E−19
The origin of a local coordinate system defining the free curved surface S23 of the free curved mirror 5 is on the optical axis of the projection lens 2. A normal to the free curved mirror 5 at the origin of the local coordinate system aligned with the z-axis of the local coordinate system is turned counterclockwise through an angle of 29°. In FIG. 3, counterclockwise turning is turning through a positive angle and clockwise turning is turning through a negative angle. Thus, a central light ray emerging from the center of the screen of the display device 11 travels substantially along the optical axis of the projection lens 2 is reflected by the free curved surface S23 of the free curved mirror 5 in a direction at an angle twice the inclination of the z-axis, namely, 58°, to the optical axis of the projection lens 2. Suppose that a new optical axis, behind the free curved mirror 5, passing the origin of the coordinate system defining the free curved surface S23 extends in a direction at an angle twice the inclination of the normal to the free curved surface S23 to the optical axis of the projection lens 2, and surfaces lying downstream of the free curved surface S23 are arranged on the new optical axis. An intersurface distance of −400 indicated in a row indicated by S23# in Table 1 signifies that the origin of a local coordinate system defining a surface S24 is at a distance of 400 mm along the new optical axis to the right from the top of the free curved surface S23. The rest of the surfaces are arranged in conformity with the same rule. TABLE 4 Surface ADE (°) YDE(mm) S0 −1.163 0.0 S23 29.000 0.0 S24 −43.000 0.0 S25 30.000 0.0
It is known from Tables 1 and 3 that curvature c and conic coefficient k are zero. Trapezoidal distortion resulting from oblique projection is large in the direction of oblique projection and is small in a direction perpendicular to the direction of oblique projection. Therefore, the function of the projection optical system to correct the distortion with respect to the direction of oblique projection needs to be greatly different from that of the same to correct the distortion with respect to a direction perpendicular to the direction of oblique projection. Thus an asymmetric aberration can be satisfactorily corrected without using the curvature c and the conic coefficient k that function in all directions rotationally symmetrically. Numerical values shown in Tables 1 to 4 apply to a case where an image of 16 mm×9 mm on the object plane is projected on the screen 3 in an image of 1452.8 mm×817.2 mm on the image plane. FIG. 5 shows the distortion of the image projected on the screen 3 in the foregoing manner. In FIG. 5, a direction parallel to the y-axis corresponds to a vertical direction in FIG. 3, and a direction parallel to the x-axis is a direction on perpendicular to the y-axis on the screen 3. The center of a rectangle shown in FIG. 5 corresponds to the center of the screen. FIG. 5 indicates a distortion by curves of straight, horizontal lines vertically dividing the rectangle into four divisions and straight, vertical lines horizontally dividing the rectangle into eight divisions. FIG. 6 is a diagram of spots formed on the screen 3 by the projection optical system defined by the numerical data shown in Tables 1 to 4. A top spot to a bottom spot shown in FIG. 6 are those formed by light rays emerged from eight points on the screen of the display device 11, namely, eight points designated by coordinates (8, 4.5), (0.4, 5), (4.8, 2.7), (8, 0), (0, 0), (4.8, −2.7), (8, −4.5) and (0, −4.5), respectively. The unit of the coordinates is millimeter. Horizontal and vertical directions in FIG. 6 correspond to directions parallel to the X-axis and the Y-axis on the screen 3, respectively. The spots are satisfactory with respect to both the directions.
FIG. 10(a) is a top view of the free curved lens 15 shown in FIG. 8 and FIG. 10(b) is a front elevation of the free curved lens 15. The free curved lens 15 has a lens body having an exit surface 20, and fringing parts 17 connected to the opposite ends of the lens body by connecting parts 19, respectively. Light rays effective in forming an image on the screen 3 pass through the lens body. The fringing parts 17 are used for holding the free curved lens 15 and for measurement. The upper surfaces 18 of the connecting parts 19 are the horizontal reference surfaces of the free curved lens 15. As shown in FIG. 10(b), the fringing parts 17 have the shape of a segment of a circle having its center on the optical axis of the free curved lens 15.
Therefore, the free curved lens 15 of the present invention is provided with the fringing parts 17 having the shape of a circular arc and the reference surfaces 18. As shown in FIG. 10(b), the fringing parts 17 have the shape of apart of a circle. The fringing parts 17 do not need to be formed in the shape of an entire circle. The fringing parts 17 needs to have the shapes of diametrically opposite segments of a circle having its center on the optical axis of the free curved lens 15. The fringing parts 17 have a thickness parallel to the optical axis. The circle circumscribing the fringing parts 17 is perpendicular to the optical axis. Each horizontal reference surface 18 is formed at least on either of the upper and the lower end of the connecting part 19 connecting the fringing part 17 to the lens body of the free curved lens 15. The horizontal reference surfaces 18 are parallel to the optical axis of the free curved lens 15. The horizontal reference surfaces 18 will be described with reference to FIG. 12. The respective origins of coordinate systems designating points on the entrance and the exit free curved surface of the free curved lens 15 are on the optical axis of the free curved lens 15. The X-, the Y- and the Z-axis of the coordinate system designating points on the entrance surface of the free curved lens 15 and those of the coordinate system designating points on the exit surface of the same are parallel to each other. The Z-axes of the coordinate systems are parallel to the optical axis. First, the shape of the circle having parts coinciding with the outlines of the fringing parts is measured to define a plane perpendicular to the optical axis of the free curved lens 15 before measuring the free curved surfaces. The positions of the origins of the coordinate systems designating points on the free curved surfaces can be determined with reference to the center of the circle having parts coinciding with the outlines of the fringing parts 17. When the entrance and the exit surface of a free curved lens are free curved surfaces, respectively, it is preferable that circles circumscribing the fringing parts 17 have the same radius because such a free curved lens can be securely held in a cylindrical lens barrel.
FIG. 13(a) is a top view of the free curved lens 16 of the rear lens group 13 of the projection lens 2, FIG. 13(b) is a front elevation of the free curved lens 16 and FIG. 14 is a perspective view of the free curved lens 16. Referring to FIGS. 13 and 14, the free curved lens 16 has a lens body having an exit surface 41, fringing parts 42, connecting parts 44 connecting the fringing parts 42 to the lens body. The upper or the lower end surface of each connecting part 44 is a horizontal reference surface 43. As obvious from FIG. 13(b), the fringing parts 42 have the shape of a segments of a circle having its center on the optical axis of the free curved lens 16.
FIGS. 15(a), 15(b) and 16 are a top view, a front elevation and a perspective view, respectively, of a free curved lens 15 included in a rear lens group 13 included in a projection lens 2 included in a projection display in a second embodiment according to-the present invention. The free curved lens 15 has a lens body and is provided with a lower fringing part connected to the lower side of the lens body in addition to side fringing parts 25 connected to the opposite lateral sides of the lens body. As obvious from FIG. 15, although any fringing part cannot be formed on the upper side of the free curved lens 15 because light rays traveling toward a screen pass near the upper side of the free curved lens 15, the lower fringing part can be formed on the lower side of the free curved lens 15. The free curved lens 15 shown in FIGS. 15 and 16 have an exit surface 20 identical with that of the free curved lens 15 included in the first embodiment shown in FIGS. 10 and 11. The side fringing parts 25 are connected to the lens body by connecting parts 27 having upper end surfaces serving as horizontal reference surfaces 26. As obvious from FIG. 15 (b) , the side fringing parts 25 are segments of a circle having its center on the optical axis of the free curved lens 15.
wherein the first optical system includes a rotationally asymmetric optical lens having fringing parts circumscribed by a circle having the center on the optical axis of the rotationally asymmetric lens.
6. The projection display according to claim 3, wherein the rotationally asymmetric optical lens has an exit surface, and a part of the exit surface from which emergent light travels toward the second optical system at a large angle to the optical axis has a curvature smaller than that of a part of the same from which emergent light travels toward the second optical system at a small angle to the optical axis.
a first optical system including a plurality of transmission lenses for enlarging the image to be displayed; and
a second optical system for reflecting light traveled through the first optical system to project an enlarged image to be displayed at a predetermined angle;
wherein at least one of the plurality of transmission lenses is a free curved lens, in which at least either an exit surface or an entrance surface is a free curved surface, having fringing parts circumscribed by a circle having the center on the optical axis of the free curved surface and having thickness parallel to the optical axis.
8. The projection display according to claim 7, wherein the rotationally asymmetric optical lens has fringing parts formed opposite to each other with respect to the optical axis and having outlines of a shape resembling a circular arc.
9. The projection display according to claim 7 further comprising a lens barrel, for holding the rotationally asymmetric optical lens, having at least a part having a cylindrical inside surface of a radius equal to that of the circle circumscribing the fringing parts of the rotationally asymmetric optical lens.
10. The projection display according to claim 9, wherein the rotationally asymmetric optical lens has a plurality of flat surfaces parallel to the optical axis in parts of the circumference, and the lens barrel is provided with a plurality of holding surfaces with which the flat surfaces of the rotationally asymmetric optical lens come into parallel contact and a holding spring.
11. The projection display according to claim 7, wherein the rotationally asymmetric optical lens has fringing parts formed opposite to each other with respect to the optical axis and having outlines of a shape resembling a circular arc.
12. The projection display according to claim 9, wherein the first optical system is a projection optical system having a front lens group including rotationally symmetric lenses, and a rear lens group including the rotationally asymmetric optical lens.
13. The projection display according to claim 10, wherein the rotationally asymmetric optical lens has an exit surface, and a part of the exit surface from which emergent light travels toward the second optical system at a large angle to the optical axis has a curvature smaller than that of a part of the same from which emergent light travels toward the second optical system at a small angle to the optical axis.
14. A transmission lens having an entrance surface on which incident light falls and an exit surface from which emergent light emerges; wherein at least either of the entrance and the exit surface is a rotationally asymmetric free curved surface, and fringing parts are formed on the fringe of the free curved surface opposite to each other with respect to the optical axis of the free curved surface and the fringing parts have outlines of a shape resembling a circular arc of a circle having the center on the optical axis of the free curved surface.
15. The transmission lens according to claim 14, wherein both the entrance and the exit surface are free curved surfaces, respectively, and a circle circumscribing the entrance surface has a radius equal to that of a circle circumscribing the exit surface.
16. An optical system for a projection display, said optical system comprising:
a first optical system including a projection lens, for projecting an image formed by the display device in an enlarged image on a screen, having a front lens group including a coaxial optical system having surfaces symmetric with respect to an axis passing the center of the display device and a rear lens group including at least one rotationally asymmetric free curved lens in which either of or both the entrance and the exit surface thereof are free curved surfaces; and
wherein the rotationally asymmetric free curved lens of the first optical system has an outline circumscribed by a circle perpendicular to the optical axis of the rotationally asymmetric free curved lens and having the center on the optical axis of the rotationally asymmetric free curved lens.
US11/473,087 2005-12-16 2006-06-23 Projection display, projection optical system and transmission lens or free curved lens Active 2028-10-04 US7670007B2 (en)
JP2005362594A JP4910384B2 (en) 2005-12-16 2005-12-16 Free-form optical element and projection optical unit or projection-type image display apparatus including the same
US7670007B2 US7670007B2 (en) 2010-03-02
US11/473,087 Active 2028-10-04 US7670007B2 (en) 2005-12-16 2006-06-23 Projection display, projection optical system and transmission lens or free curved lens
US20170064268A1 (en) * 2015-08-26 2017-03-02 Yasuyuki Shibayama Image display apparatus and image display unit
JP5405331B2 (en) * 2010-01-15 2014-02-05 富士フイルム株式会社 Projection lens barrel and method of assembling the same
CN107407864A (en) * 2015-03-10 2017-11-28 日立麦克赛尔株式会社 Projection-type image display device
2005-12-16 JP JP2005362594A patent/JP4910384B2/en not_active Expired - Fee Related
2006-06-23 US US11/473,087 patent/US7670007B2/en active Active
2006-07-24 CN CN 200610106442 patent/CN100443944C/en active IP Right Grant
US9864260B2 (en) * 2015-08-26 2018-01-09 Ricoh Company, Ltd. Image display apparatus and image display unit
US7670007B2 (en) 2010-03-02
JP2007164007A (en) 2007-06-28
JP4910384B2 (en) 2012-04-04
CN1982935A (en) 2007-06-20
CN100443944C (en) 2008-12-17
US8408717B2 (en) 2013-04-02 Projection type image display apparatus
US20020041453A1 (en) 2002-04-11 Optical element