JP5303740B2 - Projection display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type display device capable of displaying an image, by enlarging the image of an image display element and projecting the image onto a substantially horizontal plane such as a table. <P>SOLUTION: A reflection mirror for reflecting light from a light source is disposed so that an optical axis of the light source may be substantially perpendicular to an optical axis of a lens group including a plurality of lens elements disposed symmetrically about the optical axis. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

  The present invention enables image display by enlarging and projecting an image of a video display element on a substantially vertical surface, and also enabling image display by enlarging and projecting on a substantially horizontal surface such as a desk. The present invention relates to a projection display device.

  As described in Japanese Patent Application Laid-Open No. 5-134213, the projected image is shifted in a direction perpendicular to the optical axis of the projection optical system and is inclined at a predetermined angle with respect to the optical axis of the projection optical system. There is known a projection display device that enlarges and projects an image in an oblique direction with respect to a screen using the additional optical system. The additional optical system (afocal converter) referred to here is an optical system that has an effect of converting the size of the projected image, and corrects / reduces the distortion of the projected image due to the projection from the oblique direction with respect to the screen. In order to obtain a rectangular projection image.

Japanese Patent Laid-Open No. 5-134213

  As shown in FIG. 13, most of the usage forms of the conventional projection display device are provided with a screen or the like (not shown) on a substantially vertical surface such as a wall surface 19, and a table 20 at a position away from the wall surface 19. The projection type display device 101 is disposed on the screen, and the projection image 5 is projected onto the screen. Hereinafter, the installation state of the projection display apparatus 101 as shown in FIG.

  In addition to the use state as described above, in recent years, there is an increasing demand for projection onto a substantially horizontal surface such as a table.

  FIG. 12 is a diagram illustrating a state in which an image is projected onto a substantially horizontal surface such as the table 14 using the conventional projection display device 101. As shown in FIG. 12A, the conventional projection display device 101 is fixed to the ceiling 15 by the fixing member 16 so that the projection direction is downward, and the projection image 5 is displayed on the table 14. That is, the projection display device 101 must be fixed to the ceiling 15. However, as shown in FIG. 12A, it is not only used for projecting onto a substantially horizontal surface such as a table. Of course, as shown in FIG. 13, there is also an application for projecting onto a substantially vertical surface such as a wall surface. Therefore, the operation of attaching / detaching the projection display device 101 to / from the ceiling 15 occurs depending on the use situation, and the usability is not good.

  Further, as shown in FIG. 12B, the projection display device 101 is arranged on the table 14 and projected upward, and the folding mirror 17 is arranged in the middle of the projection optical path (fixed to the table 14 by the fixing member 18). There is a method in which the projection optical path is bent and projected onto the table 14. In the case of this method, the projection display device 101 does not need to be fixed and is on the table 14. From this state, simply changing the projection direction of the projection display device 101 and arranging the projection display device 101 is easy. It can project on a substantially vertical surface such as a wall. Hereinafter, the installation state of the projection display device as shown in FIGS.

  However, the projection optical unit described in Japanese Patent Laid-Open No. 5-134213 decenters the additional optical system (afocal converter) arranged on the projection surface side, and it is difficult to widen the angle. Therefore, in order to obtain a projection image with a required magnification, the distance from the projection device to the projection surface (hereinafter referred to as the projection distance) becomes long. That is, when the projection optical unit described in Japanese Patent Laid-Open No. 5-134213 is used for projection as shown in FIG. 12B, the folding mirror 17 must be arranged above in order to obtain a projection image with a necessary magnification. I must. Further, the folding mirror 17 is necessary only when projecting on a substantially horizontal surface such as the table 14, and is installed and removed according to the use situation, so that the usability is not good. Even if the wide angle can be realized, since the folding mirror 17 protrudes largely toward the projection image 5 side (left direction in the figure), from the person on the opposite side to the projection image 5 of the projection display device 101, There also arises a problem that the folding mirror 17 is in the way and the projected image 5 cannot be seen.

  The present invention has been made in view of the above-described problems, and provides a projection display device capable of displaying an image by enlarging an image of a video display element and projecting the image on a substantially horizontal surface such as a table. The purpose is to provide.

  One aspect of the present invention is a reflective mirror that reflects light from a light source so that the optical axis of the light source and the optical axis of a lens group having a plurality of lens elements arranged symmetrically with respect to the optical axis are substantially perpendicular. Place.

  According to the present invention, it is possible to project an image with a wide angle and a minimum distance to the projection surface (screen), suppressing distortion and aberration, and having good performance, convenience and convenience. A projection type display device is realized.

1 is an overall view of a projection display device according to Embodiment 1. FIG. FIG. 3 is a cross-sectional view of a projection optical unit of the projection display device according to the first embodiment. It is a figure which shows the whole state which projected the projection type display apparatus of Example 1 on the substantially perpendicular | vertical surface. It is a perspective view which shows an example of lens arrangement | positioning in the projection optical unit of FIG. It is sectional drawing for demonstrating the lens surface of a projection optical unit. It is sectional drawing for demonstrating the optical axis of a projection optical unit. 1 is an overall view of a projection display device different from FIG. 1 of Embodiment 1. FIG. It is a perspective view which shows an example of lens arrangement | positioning of the projection optical unit in the projection type display apparatus of FIG. FIG. 8 is an overall view of a state in which the projection display device of FIG. 7 is projected onto a substantially vertical surface. FIG. 3 is a YZ sectional view showing an optical path in the projection display device of Example 1. FIG. 3 is an XZ sectional view showing an optical path in the projection display device of Example 1. It is a figure which shows the state projected on the substantially horizontal surface in the conventional projection type display apparatus. It is a figure which shows the state projected on the substantially perpendicular | vertical surface in the conventional projection type display apparatus.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a perspective view illustrating a projection display apparatus according to the first embodiment. In this figure, a projection display device 100 has a substantially box-shaped housing, and generates, for example, a video display element 1 for displaying an image or video input from the outside and white light with high luminance. A light source 8 such as a lamp is provided, and the light emitted from the light source 8 changes its direction about 90 degrees by the reflection mirror 9 (first reflection portion) and is irradiated to the image display element 1. A projection optical unit for enlarging and irradiating the optical image modulated by the video display element 1 is mounted. The projection optical unit is a transmission (lens) formed by a prism (not shown), two lens groups including a front lens group (first lens group) 2 and a rear lens group (second lens group) 3. The optical system and a reflecting optical system including a reflecting mirror (hereinafter referred to as a free-form curved mirror) 4 having a free-form reflecting surface that is not rotationally symmetric (that is, non-rotational symmetric). The light reflected by the free-form surface mirror 4 (second reflecting portion) is imaged on the table 14 and displayed as a projection image 5. That is, the projection image 5 is displayed on the same surface as the placement surface of the projection display device 100 (the upper surface of the table 14).

  FIG. 2 is a diagram illustrating a projection optical unit of the projection display apparatus according to the first embodiment. FIG. 2 shows a cross section (YZ cross section) viewed from the X direction in FIG. As described above, the projection optical unit has two lens groups including the video display element 1 that emits light from the light source 8 and emits a desired video, the prism 10, the front lens group 2, and the rear lens group 3. And a reflection optical system including the free-form surface mirror 4.

  As the video display element 1, for example, a transmission type typified by a liquid crystal panel is shown, but a reflection type video display element may be used. Further, the video display element 1 may be a system that synthesizes a plurality of R, G, and B images, such as a three-plate type. In that case, a video synthesizing prism or the like is required.

  In the projection optical unit described above, the light emitted from the image display element 1 via the prism 10 is first incident on the front lens group 2 which is a lens optical system. Although the details will be described later, the front lens group 2 includes a plurality of refractive lenses having a positive power and a negative power having a rotationally symmetric surface shape. Thereafter, the light emitted from the front lens group 2 is a plurality of lenses including a plurality of (two in the first embodiment) lenses having a free-form surface shape in which at least one surface is not rotationally symmetric (rotationally asymmetric). It passes through the rear lens group 3 to be formed. The light emitted from the rear lens group 3 is further magnified and reflected by a reflection optical system including the free-form surface mirror 4 and then projected onto a table 14 (not shown) as a predetermined projection image 5. .

  In the first embodiment, as is clear from FIG. 2, the projection screen (display element) is shifted in the direction perpendicular to the optical axis of the projection system as in the background art described above. Unlike the optical system in which the additional optical system is arranged at a predetermined angle with respect to the optical axis, the video display element 1 is arranged so that the center of the display screen is positioned substantially on the optical axis of the lens optical system. (Ie, forming a coaxial optical system). Therefore, the light beam 11 that exits from the center of the display screen of the video display element 1 and passes through the center of the entrance pupil of the lens optical system toward the center of the screen on the projection image 5 is substantially the lens optical system (the front lens group 2 and the rear side). It proceeds along the optical axis of the lens group 3 (including the lens group 3) (hereinafter, this is referred to as “screen center ray”). Thereafter, the central ray 11 of the screen is reflected at the point P2 on the reflection surface of the free-form curved mirror 4, and then is directed to the point P5 at the center of the screen on the projection image 5 in the -Y direction ( Incident from the left. This angle is hereinafter referred to as “oblique incident angle” and is represented by θs. This means that the light beam that has passed along the optical axis of the lens optical system is obliquely incident on the projection surface, so that the optical axis of the lens optical system is substantially oblique to the projection surface. It means that it is provided (becomes an oblique incidence system).

  As described above, when a light beam is incident obliquely on the projection surface, the rectangular shape projected from the image display element 1 becomes a trapezoid, including so-called trapezoidal distortion, and in addition to the optical axis. Therefore, various aberrations are caused by the fact that it is not rotationally symmetric. However, in the first embodiment, these are corrected by the rear lens group 3 of the lens optical system. A free-form surface mirror that is a reflection optical system has an advantage that chromatic aberration of magnification does not occur due to a wide angle.

  In particular, when the light beam emitted from the image display element 1 is reflected by the reflecting surface of the free-form surface mirror 4 and is incident obliquely on the projection image 5, the amount of eccentricity (deflection angle) of the light obtained by the lens. ), A larger amount of decentering (deflection angle) can be obtained, and aberrations are less likely to occur. Therefore, it is possible to suppress an increase in the size of the apparatus and achieve a wide angle of view. In other words, the lens optical system including the front lens group 2 and the rear lens group 3 has a smaller aperture than that of the above-described background art additional optical system (afocal converter) and suppresses trapezoidal distortion. It becomes possible.

  Further, as described above, the light incident on the reflecting surface of the reflecting mirror 4 forming the reflecting optical system is projected to be enlarged to a predetermined size by the lens optical system, so that the manufacture thereof is facilitated. That is, the lens optical system is manufactured separately from the reflection optical system, and then the positions of both of them are fixed and adjusted in the apparatus casing, so that they are particularly suitable for mass production.

  If the rear lens group 3 for correcting trapezoidal distortion or the like is arranged in front of the front lens group 2 as described above, the interval between the rear lens group 3 and the front lens group 2 is reduced. Therefore, the apparatus on which the projection optical unit is mounted can be made compact as a whole.

  In this way, by combining a transmissive lens optical system having a free-form surface with a reflective optical system having a free-form surface, the wide field angle that is strongly required can be realized reliably and relatively easily. And it becomes possible to implement | achieve as a compact projection type display apparatus which made the whole apparatus small.

  FIG. 3 shows a state in which the projection display device 100 according to the first embodiment is placed substantially horizontally and the projection image 5 is displayed on a substantially vertical surface such as the wall surface 19. As described above, the projection image can be displayed on both a substantially horizontal surface such as a table and a substantially vertical surface such as a wall surface only by changing the installation method of the projection display device 100.

  As shown in FIG. 1, when projecting on a substantially horizontal surface, viewing is often performed from the left direction (+ Y direction) in the figure. Accordingly, the lower portion of the projection screen 5 is in the + Y direction as shown by the image of the person 150. On the other hand, when projecting onto a substantially vertical surface as shown in FIG. 3, the bottom of the projection screen 5 is the downward direction (−Y direction) in the figure as shown by the image of the person 150. As described above, since the vertical direction of the image projected by the projection surface is different, the image is upside down in one state as it is. In this case, it is necessary to display the image display element 1 by inverting it vertically and horizontally. The reversal of these images (optical images) may be switched by the reversing unit (not shown) according to the use situation, but a gravity sensor or the like is disposed in the apparatus to detect the installation state of the apparatus. It may be detected by a detection unit (not shown) and automatically switched. In the above description, both the upper and lower sides and the left and right sides are inverted, but only the upper and lower sides may be inverted.

  At this time, the reflection mirror 9 is disposed between the light source 8 and the image display element 1 so that the optical axis 8c of the light source 8 and the optical axis 3c of the rear lens 3 are substantially perpendicular. In general, a lamp such as a high-pressure mercury lamp, a halogen lamp, a xenon lamp, an LED, or a laser light source is often used as the light source 8. For example, when a high-pressure mercury lamp is used, the lamp is designed to have a long life by using the light source 8 so that the direction of the optical axis is either horizontal or vertical with respect to gravity. ing. That is, there is a problem that the life is shortened when used in a direction different from the direction designed to have a long life. In the projection type display apparatus 101 of the first embodiment, the optical axis 8c of the light source 8 and the optical axis 3c of the rear lens group 3 are made substantially vertical so that they are substantially vertically placed (FIG. 1) and substantially horizontally placed ( The optical axis 8c of the light source 8 is substantially horizontal in any state of FIG. 3) so as to extend the life.

  4 and 5 are diagrams showing optical elements including a lens optical system and a reflection optical system of the projection optical unit of the projection display device. 4 is the same as X in FIGS. 1 and 2, and the optical axes of the front lens group 2 and the rear lens group 3 are Z ′ axes, and the axes perpendicular to X and Z ′ are the same. The Y ′ axis. As will be described later, the Z ′ axis is different from the Z axis in FIGS. 1 and 2. FIG. 5 shows a Y′Z ′ cross section (FIG. 5A) and an XZ ′ cross section (FIG. 5B) of FIG. 4, respectively.

  As shown in these figures, in the lens optical system, an image emitted from the image display element 1 through the prism 10 is first incident on the front lens group 2 including a plurality of rotationally symmetric lenses. The As described above, the front lens group 2 includes a rotationally symmetric spherical lens and an aspheric lens.

  The rear lens group 3 is formed by at least two free-form surface lenses. As shown in these figures, the free-form surface lens 31 closest to the reflecting surface S23 of the reflecting mirror 4 has a concave portion in the light emitting direction, and the −Y ′ side end of the projection surface (FIG. 4). The curvature of the portion through which the light ray incident on the lower side in FIG. 4 passes is set larger than the curvature of the portion through which the light ray incident on the + Y ′ side end (upper side in FIG. 4) of the projection surface passes. That is, the free-form surface lens is curved with its concave portion facing in the light emitting direction, and the curvature of the portion through which the light ray incident on the −Y ′ side end of the projection surface passes is + Y ′ of the projection surface. It shall have a shape larger than the curvature of the part through which the light ray incident on the side end passes.

  Moreover, in Example 1, it forms so that the following conditions may be satisfy | filled. That is, in the cross section shown in FIG. 2, a light ray that is emitted from the left end of the screen of the image display element 1 and passes through the center of the entrance pupil of the front lens group 2 and enters the point P6 at the right end of the screen of the projected image 5 To do. The optical path length from the point P3 where the light ray 12 passes through the free-form surface mirror 4 to the point P6 on the projection surface is defined as L1. Also, a light ray that is emitted from the right end of the screen of the image display element 1 and passes through the center of the entrance pupil of the front lens group 2 and enters the point P4 at the left end of the screen of the projection surface is referred to as a light ray 13. The optical path length from the point P1 where the light ray 13 passes through the free-form surface mirror 4 to the point P4 on the projection surface is L2. And in the projection optical unit mentioned above, L1 and L2 are formed so that the following formula may be satisfied.

  However, Dv is the size of the screen on the projection plane in the cross section of FIG. 2, in other words, the distance from the point P6 at the right end of the screen to the point P4 at the left end of the screen on the projection plane. Θs is an oblique incident angle.

  On the other hand, the video display element 1 is arranged so that the center of the display screen is located on the optical axis of the lens optical system. Alternatively, as shown in FIG. It is desirable to arrange the optical system slightly inclined with respect to the optical axis of the optical system.

  2, as described above, the optical path length from the point P3 to the point P6 is longer than the optical path length from the point P1 to the point P4. This means that the image point P6 on the projection surface is farther than the image point P4 when viewed from the lens optical system. Therefore, an object point corresponding to the image point P6 on the projection surface (a point on the left of the display screen) is closer to the lens optical system, and an object point corresponding to the image point P4 is further away from the lens optical system. If there is, the inclination of the image plane can be corrected. For this purpose, as shown in FIG. 6, the normal vector at the center of the display screen of the video display element 1 is set with respect to the optical axis of the lens optical system in the plane including the normal line of the projection image 5 and the central ray of the screen. It is preferable to slightly tilt it. And the direction of the inclination is preferably the opposite direction to the direction in which the projection image 5 is located.

  In order to obtain an image plane tilted with respect to the optical axis, a method of tilting the object plane is known. However, at an angle of view of a practical size, the image plane due to the tilt of the object plane is not relative to the optical axis. As a result, it was difficult to correct with a rotationally symmetric projection lens. In Example 1, since the rotationally asymmetric free-form surface lens 31 and the free-form surface lens 32 are used in the rear lens group 3, it is possible to cope with asymmetric image plane deformation. For this reason, by tilting the object plane, that is, tilting the display surface of the video display element, distortion of the lower-order image plane can be greatly reduced, which is effective in assisting correction of aberrations by a free-form surface.

  Next, regarding the action of each optical element, in the lens optical system, the front lens group 2 (lenses 21 to 25) forms a main lens for projecting the display screen of the video display element 1 onto the projection image 5. It corrects basic aberrations in a rotationally symmetric optical system. The rear lens group 3 (lenses 31 to 34) of the lens optical system is formed of a lens having a free-form surface shape that is not rotationally symmetric (rotational asymmetric). Further, since the reflecting optical system 4 is a reflecting surface having a free-form surface shape that is not rotationally symmetric, it mainly corrects aberrations caused by oblique incidence. As described above, the mirror 4 constituting the reflecting optical system mainly corrects trapezoidal distortion, while the rear lens group 3 of the lens optical system mainly corrects asymmetric aberrations such as image plane distortion.

  As described above, in Example 1, the reflecting optical system is formed by one reflecting surface (mirror) 4 having a free-form surface that is not rotationally symmetric, and the rear lens group 3 of the lens optical system is rotationally asymmetric on both surfaces. It includes two transmissive lenses (lenses 31 and 32 on the reflection mirror 4 side) having a free-form surface. Here, the free-form surface mirror 4 is curved so that the convex portion is directed in the reflection direction. The curvature of the portion of the free-form curved mirror 4 that reflects the light incident on the device side end of the projection surface is set to be larger than the curvature of the portion of the projection surface that reflects the light incident on the side opposite to the device. In addition, the portion that reflects the light incident on the device side end of the projection surface has a convex shape with respect to the reflection direction, while the portion that reflects the light incident on the non-device side end of the projection surface is in the reflection direction. You may make it make concave shape.

  The distance in the optical axis direction between the coordinate origin on the reflecting surface (mirror) 4 of the reflecting optical system and the lens surface closest to the reflecting surface (mirror) 4 in the front lens group 2 is the focal point of the front lens group 2. It is desirable to set the distance 5 times or more. According to this, the trapezoidal distortion aberration can be more effectively corrected by the reflecting surface having the free-form surface of the reflecting optical system, so that good performance can be obtained.

  7, 8, and 9 are explanatory diagrams of the projection display device in the case where the folding mirror 35 is disposed between the front lens group 2 and the rear lens group 3.

  As shown in the figure, the optical axis of the front lens group 2 and the optical axis of the rear lens group 3 are approximately 90 ° by the folding mirror 35 (first reflecting portion). In this case, the optical axis 8c of the light source 8 and the optical axis 3c of the rear mirror group 3 are substantially vertical without arranging a reflection mirror between the video display element 1 and the light source 8. Since the action, effect, etc. are not different from the above, the description is omitted here.

  Next, specific numerical examples of the first embodiment will be described.

  First, with reference to FIGS. 10 and 11 and Tables 1 to 4 below, details of the projection optical unit according to the first embodiment described above are included, particularly including its lens optical system and reflection optical system. Description will be made while showing specific numerical values of the optical element. These drawings show ray diagrams of the optical system of Example 1 based on the first numerical example. That is, FIG. 10 shows a YZ section in the XYZ orthogonal coordinate system of FIG. 1, and FIG. 11 shows an XZ section. In FIG. 11, the detailed structure is shown in FIGS. 7 and 8, and a bending mirror 35 is installed in the middle of the front lens group 2 and the rear lens group 3 of the lens optical system forming the lens optical system. An example in which the optical path is bent once in the X-axis direction is shown.

  The light emitted from the image display element 1 displayed on the left side of FIG. 10 first passes through the front lens group 2 formed of only lenses having only rotationally symmetric surfaces in a lens optical system including a plurality of lenses. . Then, the light passes through the rear lens group 3 including a rotationally asymmetric free-form surface lens and is reflected by the reflection surface of the free-form surface mirror 4 which is a reflection optical system. The reflected light is then incident on the projected image 5.

  Here, the front lens group 2 of the lens optical system is formed of a plurality of lenses having a rotationally symmetric refracting surface, and four of the refracting surfaces of these lenses are rotationally symmetric aspherical surfaces. The others are spherical. The rotationally symmetric aspherical surface used here is expressed by the following equation using a local cylindrical coordinate system for each surface.

  Here, “r” is the distance from the optical axis, and “Z” represents the sag amount. “C” is the curvature at the apex, “k” is the conic constant, and “A” to “J” are coefficients of the power term of “r”.

  On the other hand, the free-form surface which is the rear lens group 3 of the lens optical system uses a local orthogonal coordinate system (x, y, z) with the surface vertex of each surface as the origin, and includes the following equations including X and Y polynomials: It is represented by

  Here, “Z” represents the sag amount of the shape of the free-form surface in the direction perpendicular to the X and Y axes, “c” is the curvature at the apex, and “r” is the plane in the X and Y axes. The distance from the origin, “k” is a conic constant, and “C (m, n)” is a polynomial coefficient.

  Next, Table 1 shows numerical data of the optical system according to Example 1. In Table 1, S0 to S23 correspond to the codes S0 to S23 shown in FIG. Here, reference sign S0 indicates the display surface of the image display element 1, that is, the object surface, and S23 indicates the reflective surface of the free-form surface mirror 5. Further, reference numeral S24 is not shown in these drawings, but indicates an incident surface, that is, an image surface of the projection image 5 in FIG.

  In Table 1, “Rd” is the radius of curvature of each surface. In FIG. 5, when the center of curvature is on the left side of the surface, it is expressed as a positive value, and in the opposite case, it is expressed as a negative value. In Table 1, “TH” is the inter-surface distance, which indicates the distance from the apex of the lens surface to the apex of the next lens surface. When the next lens surface is on the left side in the figure, the inter-surface distance is expressed as a positive value, and when it is on the right side, it is expressed as a negative value.

  Furthermore, in Table 1, S5, S6, S17, and S18 are rotationally symmetric aspherical surfaces. In Table 1, "*" is added next to the surface number for easy understanding. The spherical coefficients are shown in Table 2 below.

  In Table 1, S19 to S22 are refracting surfaces having a free-form surface forming a rear lens group of the lens optical system, and S23 is a reflecting surface having a free-form surface S23 shape of the reflecting optical system. # Is displayed next to the number. The coefficient values representing the shapes of these five free-form surfaces are shown in Table 3 below.

  In this numerical example, as shown in FIG. 6, the object surface which is the display screen of the image display element 1 is inclined by −1.163 degrees with respect to the optical axis of the lens optical system. Note that the direction of the inclination is represented by a positive value in the direction in which the normal of the object surface rotates clockwise in the cross section of FIG. Therefore, in this numerical example, the object surface is inclined 1.163 degrees counterclockwise from the position perpendicular to the optical axis of the lens optical system in the cross section of FIG.

  Further, the free-form surface mirror 4 indicated by reference numeral S23 in FIG. 5 or 6 places the origin of the local coordinates on the optical axis of the lens optical system, and the normal line at the origin of the local coordinates, that is, the Z axis, The lens is tilted by about +29 degrees from a position parallel to the optical axis of the lens optical system. Note that the direction of this inclination is the same as the object surface, and the direction that rotates counterclockwise in the cross section of FIG. 5 or 6 is positive, and therefore, it is inclined counterclockwise. As a result, the screen center ray that has exited from the center of the screen of the image display element 1 and has traveled substantially along the optical axis of the lens optical system is reflected by S23 and then is reflected with respect to the optical axis of the lens optical system. Proceed in a direction inclined by 58 degrees, which is twice the inclination angle (see arrow in the figure).

  Further, Table 4 shows the state of inclination or eccentricity of the local coordinate system of each surface in this numerical example. In Table 4, the inclination angle and the value of the eccentricity are shown on the right side of the surface number. “ADE” is the magnitude of the inclination in the plane parallel to the cross section of FIG. 5, and the display rule is shown above. That's right. “YDE” is the magnitude of the eccentricity, and the eccentricity is set in a direction parallel to the cross section of FIG. 5 and perpendicular to the optical axis, and the downward eccentricity is positive in the cross section of FIG. . In the embodiments described below, the inclination and decentration of the optical element are set in the direction in the cross section parallel to the displayed cross section.

  From Table 1 and Table 3, it can be seen that in this numerical example, the curvature “c” and the conic coefficient “k” are zero (0). That is, trapezoidal distortion due to oblique incidence occurs extremely large in the direction of oblique incidence, and the amount of distortion in the direction perpendicular thereto is small. Therefore, a significantly different function is required between the direction of oblique incidence and the direction perpendicular thereto, and by using the curvature “c” and the conic coefficient “k” that are rotationally symmetric and function in all directions, asymmetrical characteristics are obtained. Aberration can be corrected satisfactorily.

  In Table 4, “ADE” on the surface S23 is the same as θm shown in FIG. 2, and “ADE” on the surface of the projection image 5 is θs as shown in FIG.

  DESCRIPTION OF SYMBOLS 1 Image | video display element, 2 front lens group, 3 back lens group, 4 free-form surface mirror, 5 projection image, 8 light source, 100, 101 projection type display apparatus, 150 person.

Claims (11)

In the projection display device,
A light source that emits light;
A first reflecting portion that reflects light from the light source;
An image display element that modulates light from the first reflecting portion into an optical image;
A lens group that transmits light from the image display element and is formed of a plurality of lens elements;
A second reflecting portion that reflects light from the lens group;
An optical image in a case where the projection display device is substantially vertically placed, and a reversing unit that inverts an optical image in the case of being substantially horizontally placed, respectively,
The optical axis of the light source and the optical axis of the lens group are substantially perpendicular,
The projection type display device, wherein the second reflection unit is disposed at a predetermined angle with respect to the optical axis of the lens group.   The projection display device according to claim 1, further comprising a gravity sensor that detects an installation state of the projection display device by gravity.   The projection display device according to claim 2, wherein the reversing unit switches the optical image based on an output of the gravity sensor.   The lens group is formed of a first lens group including a lens having a rotationally symmetric surface shape, and a second lens group including a lens having at least one surface that is not rotationally symmetric. The projection type display device described in 1.   5. The projection display device according to claim 1, wherein the second reflecting portion has a shape that is non-axisymmetric with respect to an optical axis of the lens group. In the projection display device,
A light source that emits light;
An image display element that modulates light from the light source into an optical image;
A first lens group that transmits light from the image display element and is formed of a plurality of lens elements;
A first reflecting portion that reflects light from the first lens group;
A second lens group that transmits light from the first reflecting portion and is formed of a plurality of lens elements;
A second reflecting portion that reflects light from the second lens group,
The optical axis of the light source and the optical axis of the first lens group are substantially parallel,
The optical axis of the light source and the optical axis of the second lens group are substantially perpendicular,
The second reflecting portion is disposed at a predetermined angle with respect to the optical axis of the second lens group,
The light source is a projection display device in which the optical axis of the light source is arranged in a substantially horizontal direction regardless of whether the projection display device is installed in a substantially vertical state or a substantially horizontal state.   The projection display device according to claim 6, further comprising: an inverting unit that inverts the optical image when the projection display device is placed substantially vertically and the optical image when the projection display device is placed substantially horizontally.   The projection display device according to claim 7, further comprising a gravity sensor that detects an installation state of the projection display device by gravity.   The projection display device according to claim 8, wherein the reversing unit switches the optical image based on an output of the gravity sensor. The first lens group includes a lens having a rotationally symmetric surface shape;
The projection display device according to claim 6, wherein the second lens group includes a lens having at least one surface that is not rotationally symmetric.   11. The projection display device according to claim 6, wherein the second reflecting portion has a non-axisymmetric shape with respect to an optical axis of light from the second lens group.

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