JP2012118547A - Oblique projection optical system and projection type video display apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a miniaturized compact set free from trapezoidal distortion due to oblique projection and having excellent focus performance, in a projection type video display apparatus including an oblique projection optical system having an ultra-short projection distance, and also capable of achieving configuration equipped with a flat mirror.SOLUTION: A projection type video display apparatus includes an oblique projection optical system constituted of a plurality of lenses. The lens which is arranged at a position closest to a projection screen is arranged at a position where a vertical effective image area through which light flux passes does not include an optical axis shared by the largest number of the lenses among the optical axes of the plurality of the lenses. A flat mirror for returning an optical path is arranged between the lens and the projection screen at a prescribed angle to the optical axis. An enlarged image obtained by the image light flux returned by the flat mirror is formed so as to be obtained in the direction of a video display screen.

Description

  The present invention relates to a projection-type image display apparatus that enlarges and displays an image on a display screen of an image display element on a screen or a board as a projection surface, and its projection optical system, and in particular, an image projected on a display screen is displayed on a projection surface. The present invention also relates to a projection display apparatus that projects an image from an oblique direction, an optical system thereof, and a method for processing a plastic molded lens constituting the optical system.

  In a projection-type image display apparatus that enlarges and displays a display screen of an image display element having a structure in which a plurality of reflective or transmissive liquid crystal panels or micromirrors are arranged on a screen or board as a projection surface, the projection surface is sufficient. Of course, it is possible to obtain a magnified image of a size, but the projection image display device and the projection device are designed so that the shadow of the presenter is not reflected on the projection surface and that the magnified image light does not enter the eyes of the presenter directly. A so-called short projection type projection optical system in which the distance of the surface is shortened has begun to appear on the market. This projection optical system is configured such that enlarged image light is incident on the projection plane from an oblique direction (for example, Patent Document 1).

  Further, a means for performing optical adjustment with an inclined projection optical system using a curved mirror for such oblique projection is also known (for example, Patent Document 2). On the other hand, there is also known a projection image display apparatus in which an apparent projection distance is shortened by providing an optical path folding mirror between the projection image display apparatus and the projection surface to be a rear projection type. (For example, Patent Document 3)

JP 2008-250296 A JP 2002-350774 A JP 2006-259252 A

  However, in a tilted projection optical system in which enlarged image light is incident from an oblique direction with respect to the projection surface disclosed in Patent Document 1 described above, a curved mirror is disposed between the projection optical system and the projection surface. A configuration in which an intermediate image is formed between a curved mirror and the coaxial projection optical system by a coaxial projection optical system, and this intermediate image is enlarged and projected onto a screen as a projection plane by the magnification action of the curved mirror It is.

  For this reason, in the technique described in Patent Document 1, the position of the curved mirror must be translated along the optical axis of the coaxial projection optical system in order to change the magnification of the magnified image on the screen. A high-precision movement adjustment mechanism is necessary so that the curved mirror does not tilt with respect to the optical axis, but this movement adjustment mechanism is not disclosed.

  Further, the above Patent Document 2 only discloses an adjustment method by moving a free-form surface mirror, and the trapezoidal distortion of the projected image and the vertical direction of the screen accompanying oblique projection onto the screen, which is a projection surface unique to the tilt projection optical system. A specific correction for the aberration caused by the difference in projection distance is not taken into consideration, and there is no description of a method for manufacturing a free-form surface mirror having a negative power disposed between the projection optical system and the screen.

  On the other hand, the above-mentioned Patent Document 3 has a mirror mechanism section for enabling rotation of a mirror that reflects the projection light projected from the projection lens of the projector body, and this mirror mechanism section projects from the projector body to the mirror. The projector body is fixed to the fixed part so that the projection angle of light is a predetermined angle. Not only can rear projection be performed without shifting the projection lens installed inside the projector body, but also front projection ( In the case of direct projection on the screen, the projector main body is stored in the mirror mechanism, and the projector main body is designed to have a compact size when the projector main body is stored in the mirror.

  In the projector described in Patent Document 3, the positional relationship between the mirror and the projector body during rear projection is fixed, and the magnification of the magnified image on the screen during rear projection is adjusted and the position of the magnified image is adjusted. Technical means are not considered.

  The present invention has been made in view of such a problem, and an object of the present invention is an inclined projection optical system that obliquely projects onto a projection surface and a projection-type image display apparatus using the inclined projection optical system. An object of the present invention is to provide a projection image display apparatus in which the installability of a projection image display apparatus is greatly improved when aberrations are corrected with a compact configuration and projection light is folded back by a plane mirror and projected onto a projection surface.

  Further, the tilt projection optical system of the present invention is composed of a plurality of lenses including a plastic lens, and the plastic lens is aspherical, thereby reducing the processing time of the molding die as compared with the free-form surface, and the optical path. It is an object of the present invention to provide a projection display apparatus that greatly reduces development costs by using a folding mirror as a flat mirror.

  In order to achieve the above object, the projection optical system according to the present invention is a so-called tilted projection optical system that obliquely enlarges and projects an image displayed on an image display surface onto a screen or the like that is a projection surface, and includes a plurality of lenses. The lens arranged at the position closest to the projection surface is arranged at a position where the effective area in the image vertical direction through which the image light beam passes does not include the optical axis shared by the largest number of lenses among the optical axes of the plurality of lenses. However, by making the shape axially asymmetric with respect to the optical axis, it becomes possible to correct aberration caused by super wide angle and distortion caused by oblique projection.

  In addition, the tilt projection optical system of the present invention can increase the position in the vertical direction of the screen on which the enlarged image is projected with respect to the optical axis for the reasons described above, and is therefore closest to the projection plane. A small flat mirror can be disposed between the lens disposed at the position and the projection plane for returning the optical path.

  Further, in order to make the projection display device equipped with the tilted projection optical system compact, the upper end of the effective screen vertical direction of the lens arranged at the position closest to the projection surface is effective for the vertical screen of the plane mirror. Arranged at the upper part with respect to the lower end of the region, this plane mirror has a tilt adjustment optical system having a predetermined elevation angle with respect to the optical axis shared by the largest number of lenses and a rotation adjustment mechanism that makes this elevation angle variable. It is characterized by this.

  In addition, since the tilt projection optical system according to the present invention can maintain the image quality even when the angle is widened, in the projection display apparatus having the tilt projection optical system, the distance between the projection plane and the projection display apparatus is short. However, it is possible to obtain an image with a large enlargement ratio and to provide a plane mirror moving mechanism that allows the above-described plane mirror to move along the optical axis shared by the largest number of lenses. To do.

  Further, in the lens disposed at the position closest to the projection plane constituting the tilted projection optical system of the present invention, the effective image vertical direction area through which the light beam passes is shared by the largest number of lenses among the optical axes of the plurality of lenses. The optical axis is arranged at a position not including the optical axis, the shape is axisymmetric with respect to the central axis of the lens effective surface, and is non-symmetrical with respect to the optical axis shared by the most lenses. It is a shape obtained by cutting out a part of a spherical shape.

  The projection display apparatus of the present invention has an inclined projection optical system for projecting an image displayed on the image display surface in an obliquely enlarged manner on the projection surface, and the inclined projection optical system includes a plurality of lenses. The lens arranged at the position closest to the projection plane is arranged at a position where the image vertical effective area through which the light beam passes does not include the optical axis shared by the largest number of lenses among the optical axes of the plurality of lenses, The projection is housed in the range of the maximum width in the vertical direction of the screen on the surface facing the projection surface of the casing forming the projection display apparatus.

  In order to achieve the above object, a projection display apparatus according to the present invention has an inclined projection optical system that projects an image displayed on an image display surface in an obliquely enlarged manner on the projection surface, and the inclined projection optical system includes: The lens composed of a plurality of lenses and arranged at the position closest to the projection plane includes an optical axis in which the effective image vertical direction area through which the light beam passes is shared by the largest number of lenses among the optical axes of the plurality of lenses. An optical path folding plane mirror is arranged between the projection plane and the lens arranged at a position that is not located and closest to the projection plane (screen, etc.), and this plane mirror is shared by the most numerous lenses described above. In the first state, the plane mirror is arranged at a predetermined angle with respect to the optical axis shared by the above-mentioned most lenses by providing a rotation adjusting mechanism capable of changing the angle with respect to the optical axis. In the second state in which the magnified image obtained by the image light flux folded back by the mirror is obtained in the image display surface direction, while the flat mirror is housed in the projection image display device, the optical axes of the plurality of lenses described above And an enlarged image can be obtained in the direction in which the optical axis shared by the largest number of lenses is extended.

  Further, the projection display apparatus of the present invention has means for detecting the rotation angle of the plane mirror described above, and has an image correction function for automatically correcting screen distortion of the projection image according to the detected rotation angle. It is characterized by that.

  Further, the optical path folding plane mirror described above is also formed by the image light beam folded by the plane mirror when it is arranged at a predetermined angle θ1 with respect to an axis perpendicular to the optical axis shared by the above-mentioned most lenses. The enlarged image obtained is configured to obtain an enlarged image in the direction of the image display surface, and the projection image display device is arranged by being inclined by θ2 with respect to a reference plane substantially perpendicular to the enlarged image. And θ2 satisfy the following relationship:

                  1.5 ≦ θ2 / θ1 ≦ 2.0

  On the other hand, among the plurality of lenses constituting the inclined projection optical system of the present invention, the lens disposed at the position closest to the projection surface is made of plastic, and the effective area in the image vertical direction through which the light beam passes is the optical axis of the plurality of lenses. This plastic lens is arranged at a position that does not include the optical axis shared by the largest number of lenses, and this plastic lens cuts out a part of the aspherical shape symmetrical to the optical axis shared by the largest number of lenses constituting the projection optical system. It is possible to perform cutting by arranging a plurality of molding dies so as to be symmetrical with respect to the optical axis shared by the largest number of lenses in order to perform the molding dies. Has characteristics.

  According to the present invention, there is provided an inclined projection optical system that projects obliquely onto a projection surface and a projection display apparatus using the tilted optical system. When the flat mirror is designed to be housed in a projection display, and the projection light is folded back by the flat mirror and projected onto the projection surface, the angle of the flat mirror can be adjusted to change the position of the projected image and By moving the mirror in the optical axis direction and changing the magnification of the projected image, it is possible to significantly improve the installation property of the projection display apparatus.

  Furthermore, the tilt projection optical system of the present invention has a lens that is composed of a plurality of lenses and is disposed at a position closest to the projection plane, and has the largest number of effective areas in the image vertical direction through which light beams pass among the optical axes of the plurality of lenses. The processing time of the molding die is greatly reduced by arranging a part of the aspherical shape symmetrical to the optical axis by disposing it at a position not including the optical axis shared by the lenses of the optical path, and the optical path Development cost can be greatly reduced by using a mirror for the folding mirror.

The side view which shows one Embodiment of the projection type video display apparatus provided with the inclination projection optical system and optical path folding mirror of this invention The side view which shows one Embodiment of the projection type video display apparatus provided with the inclination projection optical system and optical path folding mirror of this invention The side view which shows one Embodiment of the projection type video display apparatus provided with the inclination projection optical system and optical path folding mirror of this invention The side view which shows one Embodiment of the projection type video display apparatus provided with the inclination projection optical system and optical path folding mirror of this invention The side view which shows one Embodiment of the projection type video display apparatus provided with the inclination projection optical system and optical path folding mirror of this invention The front view which shows one Embodiment of the projection type video display apparatus provided with the inclination projection optical system and optical path folding mirror of this invention The side view which shows one Embodiment of the projection type video display apparatus provided with the inclination projection optical system of this invention The front view which shows one Embodiment of the projection type video display apparatus provided with the inclination projection optical system of this invention Sectional drawing of the projection lens which shows the lens structure of the inclination projection optical system of this invention Sectional drawing showing the lens configuration and ray tracing result of the tilt projection optical system of the present invention Sectional drawing showing the lens configuration and ray tracing result of the tilt projection optical system of the present invention Sectional drawing of the projection lens which shows the lens structure of one Example (lens data shown to Fig.25 (a) (b)) of the inclination projection optical system of this invention Sectional drawing of the projection lens which shows the lens structure of one Example (The lens data shown to Fig.26 (a) (b)) of the inclination projection optical system of this invention Sectional drawing of the projection lens which shows the lens structure of one Example (The lens data shown to Fig.27 (a) (b)) of the inclination projection optical system of this invention Sectional drawing showing the lens configuration and ray tracing result of one embodiment of the tilt projection optical system of the present invention (lens data shown in FIGS. 25A and 25B) The figure showing the spot shape of the projection image by one Example (lens data shown to Fig.25 (a) (b)) of the inclination projection optical system of this invention The figure showing the spot shape of the projection image by one Example (the lens data shown to Fig.26 (a) (b)) of the inclination projection optical system of this invention The figure showing the spot shape of the projection image by one Example (The lens data shown to Fig.27 (a) (b)) of the inclination projection optical system of this invention The block diagram which showed one Example of the illumination optical system of a projection type video display apparatus. Schematic diagram of a lens surface shape processing machine for plastic lens molding dies Configuration diagram schematically showing the processing method of plastic lens molding dies by lens surface shape processing machine The figure which showed typically one Example of the plastic lens shaping die lens surface shape processing method of this invention The figure which showed typically the other Example of the plastic lens molding die lens surface shape processing method of this invention The figure which shows the external shape of the plastic lens of one Example of this invention Of the lens data that can be taken by the projection lens that realizes the tilted projection optical system as the first embodiment of the present invention, data relating to the spherical system Of the lens data that can be taken by the projection lens that realizes the tilted projection optical system as the first embodiment of the present invention, data relating to the aspheric system Of the lens data that can be taken by the projection lens that realizes the tilted projection optical system as the second embodiment of the present invention, data relating to the spherical system Of the lens data that can be taken by the projection lens that realizes the tilted projection optical system as the second embodiment of the present invention, data relating to the aspheric system Of the lens data that can be taken by the projection lens that realizes the tilted projection optical system as the third embodiment of the present invention, data relating to the spherical system Of the lens data that can be taken by the projection lens that realizes the tilt projection optical system as the third embodiment of the present invention, the data relating to the aspheric system

  Hereinafter, the best mode of the present invention will be described in detail with reference to the accompanying drawings. In each of the following drawings, elements having common functions are denoted by the same reference numerals, and repeated description of elements once described is omitted.

  1 to 3 are side views schematically showing a projection display apparatus as an embodiment of the present invention. In particular, a plane mirror (not shown) is fixed to a fixed frame 2 and image light fluxes are shown. 3 is provided with an inclined projection optical system (not shown) for projecting from an oblique direction onto a projection surface in the direction of the image display surface (not shown), and the aforementioned inclined projection optical system, illumination optical system, circuit component, etc. The main components (not shown) are housed inside the lower housing 9 and the upper housing 1a.

  In the figure, 4 is a plane mirror rotating / fixing mechanism, 5 is a rotating mechanism capable of adjusting the angle of the mirror fixing frame, and is provided with detecting means capable of detecting the elevation angle of the plane mirror if necessary. 8 is a plane mirror moving mechanism, R1 is a screen vertical direction upper limit light of the enlarged video light beam, and R2 is a screen vertical direction lower limit light of the enlarged video light beam.

  A specific example of the lens configuration that realizes the tilt projection optical system provided in the video display device of the present invention will be described in detail later.

  As shown in FIG. 2, the projection type image display apparatus of the present invention fixes a plane mirror (not shown) to the fixed frame 2 and folds the image light beam 3 so as to be oblique to the projection surface in the direction of the image display surface (not shown). Since the projection from the direction can be performed, the apparent projection distance from the image projection display device to the projection surface can be greatly reduced, and the plane mirror is moved with respect to the casing of the projection display device by the moving mechanism 8 to fix the fixed portion 6. The projection distance to the projection surface can be changed without moving the casing by fixing the fixed portion 7 at a predetermined position. As a result, not only the enlargement ratio of the image on the projection surface can be easily changed, but also the figure. 3 and 4, the angle can be adjusted from a predetermined elevation angle by the plane mirror rotating / fixing mechanism 4 or the mirror fixing frame rotating mechanism 5, and the display position of the image on the projection plane can be arbitrarily moved.

  At this time, one or both of the plane mirror rotating / fixing mechanism 4 and the mirror fixing frame rotating mechanism 5 is provided with a rotation angle detecting means (for example, a rotary encoder) capable of detecting a plane mirror rotation angle with respect to a predetermined elevation angle. The usability is further improved by automatically correcting the keystone correction in the vertical direction of the video circuit according to the obtained rotation angle.

  Further, as shown in FIG. 2, the projection type image display apparatus of the present invention fixes a plane mirror (not shown) to the fixed frame 2 and folds the image light flux 3 so that it is projected on the image display surface (not shown) direction. In order to reduce the effective area of the plane mirror when projecting from an oblique direction, the distance between the image projection display device and the plane mirror is shortened, and the shift amount of the tilt projection optical system (the projection lens optical axis overlaps the lower end of the enlarged image vertical direction). If the shift amount is 10: 0 and the width in the vertical direction of the enlarged image is 10, the negative amount is defined if the lower end in the vertical direction of the enlarged image is above the optical axis (that is, above the optical axis). Designed to be located in).

  In the image display device of the present invention, in order to further shorten the distance between the image projection display device and the plane mirror, the plane mirror is rotated from a predetermined elevation angle by the rotation / fixing mechanism 4 or the rotation mechanism 5 of the mirror fixing frame as shown in FIG. By tilting by θ1 and correspondingly tilting the image projection display device by θ2 with respect to a plane perpendicular to the projection plane, it is possible to obtain a magnified image with little distortion on the projection plane. A projection display device was prototyped and the relationship between vertical keystone distortion correction by image processing and image quality degradation was examined by experiment.

  As a result, when the ratio of θ2 and θ1 (θ2 / θ1) is 1.5 or less, the image in the upper vertical direction of the screen of the projection plane becomes too large compared to the image in the lower part, and the vertical keystone correction is performed in the image circuit. On the contrary, if the ratio of θ2 and θ1 (θ2 / θ1) is 2.5 or more, the image in the lower part of the projection screen in the vertical direction on the screen is too large compared to the upper image. It has been found that even when the vertical keystone correction is performed in the video circuit, the image quality is greatly deteriorated, and that the image quality deterioration can be most reduced when the ratio of θ2 and θ1 (θ2 / θ1) is set near 2.0.

  FIGS. 5 and 6 are diagrams schematically showing a form in the case where a plane mirror (not shown) for turning back an optical path is housed in the upper part of the set housing in the image projection display device of the present invention. FIG. 6 and 6 are front views.

  As shown in FIG. 5, the image projection display device of the present invention is fixed to a fixed frame 2 for fixing a plane mirror (not shown) for turning back an optical path, and the plane mirror rotating / fixing mechanism 4 and the mirror fixing frame rotating mechanism 5 are fixed. The moving mechanism 8, the fixed portion 6, and the fixed portion 7 can be stored in a predetermined position on the upper part of the set housing, and the light shared by the largest number of lenses constituting the inclined projection optical system without folding the optical path when the mirror is stored. Enlarged projection can be performed in a direction along the axis.

  FIG. 6 is a set front view schematically showing a form in the case where a flat mirror (not shown) for turning back an optical path is housed in the upper part of the set housing in the image projection display device of the present invention, and constitutes an inclined projection optical system. Among the plurality of lenses, the lens (shown as L17 in FIG. 6) disposed at the position closest to the projection plane has a rectangular or trapezoidal shape that is substantially equal to the aspect ratio (aspect ratio) of the effective area of the image display surface, and removes unnecessary light. A housing that forms the projection-type image display device by arranging an effective area in the image vertical direction through which a light beam passes so as not to include an optical axis shared by the largest number of lenses among the optical axes of the plurality of lenses. The design can be greatly improved by keeping the maximum width in the vertical direction of the screen facing the projection surface of the body.

  As an embodiment of the present invention, as shown in FIGS. 5 and 6, the structure of the image projection display device has been described in which a magnified image can be obtained even when the plane mirror for turning back the optical path is housed or opened. Needless to say, if the tilt projection optical system of the present invention is provided, the present invention is also in conflict with the present invention as an image projection display device that cannot be used in a state where the above-described plane mirror for turning back the optical path is housed in the housing.

  As shown in FIG. 7, the image projection display device according to another embodiment of the present invention does not include a plane mirror for turning back the optical path, and has an optical axis shared by the most lenses constituting the tilted projection optical system. It is configured to magnify and project along the direction.

  FIG. 8 is a set front view schematically showing the form of the image projection display device as another embodiment of the present invention shown in FIG. 7, and the projection surface of the plurality of lenses constituting the inclined projection optical system is shown in FIG. The lens arranged at the nearest position (shown as L17 in FIG. 8) has a rectangular or trapezoidal shape that is substantially equal to the aspect ratio (aspect ratio) of the effective area of the image display surface. The screen is perpendicular to the plane of the surface facing the projection plane of the casing that is disposed at a position that does not include the optical axis shared by the largest number of lenses among the optical axes of the plurality of lenses and that forms the projection display apparatus The maximum width can be accommodated, and the outer center of L17 described above is positioned above the center line of the surface facing the projection surface of the housing, so that the balance in appearance can be improved and the design can be greatly improved.

  Next, with reference to FIGS. 9 to 18 attached, a plurality of sheets constituting an inclined projection optical system, which is employed in the above-mentioned projection display apparatus, particularly in order to shorten the projection distance of the projection display apparatus as much as possible. Of these lenses, the lens located closest to the projection surface is a rectangular or trapezoidal shape approximately equal to the aspect ratio (aspect ratio) of the image display surface effective area, shielding unnecessary light and allowing the light beam to pass through. Will describe a slant projection optical system for short-distance projection in which the projection is performed by enlarging obliquely from a short distance by arranging it at a position that does not include the optical axis shared by the largest number of lenses among the optical axes of the plurality of lenses. .

<Inclined projection optical system for short-distance projection>
First, FIG. 9 attached herewith is a sectional view showing the basic configuration of the projection optical system, and shows the configuration of the optical system in the YZ section in the XYZ orthogonal coordinate system. Here, for convenience of description of the projection optical system, the liquid crystal panel 122 and the cross prism 111 which are image display surfaces are displayed on the right side and the projection surface is displayed on the left side. This embodiment corresponds to the lens data shown in FIGS. 27A and 27B, and the lens L17 arranged closest to the projection surface is a plastic aspheric lens shape, and the lens through which the image light flux passes. Is arranged at a position that does not include the optical axis 11 shared by a plurality of lenses constituting the tilt projection optical system, the light beam formed on the periphery of the screen can be controlled by the lens shape of L17 alone, and tilt projection is performed. Correction of the trapezoidal distortion and aberrations (particularly higher-order coma and astigmatism) caused by ultra-wide angle. Further, the lens shape of L17 is a rectangular shape substantially equal to the aspect ratio (aspect ratio) of the effective area of the image display surface or a trapezoidal shape matched to the area through which the image light beam passes, thereby shielding unnecessary light that degrades the imaging performance. There is also. Further, since the outer shape of L17 described above is not a circular shape symmetrical to the optical axis 11, the size can be reduced. As a result, the tilted projection optical system of the present embodiment is housed in the casing of the projection display apparatus. However, the outer shape of L17 can be accommodated within the maximum width in the screen vertical direction of the surface facing the projection surface, and at the same time, the outer shape center of L17 is located above the center line of the surface facing the projection surface of the housing. As a result, the balance in appearance is improved and the design can be greatly improved.

  In FIG. 9, only L17 has a lens shape that is a rectangle that is substantially equal to the aspect ratio (aspect ratio) of the effective area of the image display surface or a trapezoid shape that matches the area through which the image light beam passes (the cross-sectional shape is shown in the figure). However, in the lens configuration for realizing the tilted projection optical system of the present invention, as shown in FIG. 15, there is a region where the image light flux does not pass through the lenses such as L14 and L15. If the outer shape is determined, it is possible to reduce the size of the conventional lens outer shape symmetric with respect to the optical axis, which is effective for reducing the size and weight of the projection display apparatus having this optical system.

  On the other hand, L3 and L11 are also aspherical lenses made of plastic, but each lens includes an optical axis 11 in which the effective area of the lens through which the image light beam passes is shared by a plurality of lenses constituting the inclined projection optical system. Since it is arranged at the position, it has an aspherical shape symmetrical to the optical axis 11. The projection lens for realizing the tilted projection optical system of the present embodiment is held and fixed by a lens barrel having four components (B1, B2, B3, B4) in a 17-glass configuration of 14 glasses and 3 plastics. When the enlargement ratio is changed by changing the projection distance, the focus adjustment can be performed by changing the relative position of the lens barrel B4 with respect to the lens barrel B3.

  In the embodiment shown in FIGS. 10 to 15, the origin of the XYZ orthogonal coordinate system is the center of the display screen of the liquid crystal panel 122 that displays an image by modulating the illumination light beam with a video signal, and the Z axis is for video display. It is assumed that it is parallel to the normal line of the liquid crystal panel 122 (not shown). The Y axis is parallel to the short side of the display screen of the video display liquid crystal panel 122 (not shown), and is equal to the vertical (vertical) direction of the video display liquid crystal panel 122 (not shown). The X axis is parallel to the long side of the display screen of the video display liquid crystal panel 122 (not shown), and is equal to the horizontal (left and right) direction of the video display liquid crystal panel 122. Also, FIG. 10 attached hereto is a perspective view of a projection lens as an embodiment of an inclined projection optical system constituting the projection display apparatus, and FIG. 10 shows the projection lens without a plane mirror for bending the optical path. FIG.

  FIG. 12 is a sectional view of a projection lens that realizes the tilt projection optical system as the first embodiment of the present invention. Among the lens data that can be obtained at this time, data relating to the spherical system is shown in FIG. Data relating to the system is shown in FIG. FIG. 13 is a cross-sectional view of a projection lens that realizes the tilt projection optical system as the second embodiment. Of the lens data that can be obtained at this time, data relating to the spherical system is shown in FIG. The data is shown in FIG. Similarly, FIG. 14 shows a cross-sectional view of a projection lens that realizes an inclined projection optical system as a third embodiment. Of the lens data that can be obtained at this time, data relating to the spherical system is shown in FIG. The data regarding is shown in FIG.27 (b).

  In each lens data, the projection distances L0 and L1 shown in FIGS. 10 and 11, the shift amount S1 from the optical axis of the image display position, and the vertical size Dv of the image are summarized as follows.

L0 (mm) Dv (mm) S1 (mm)
60 "At the time of projection Example 1 650.1 747.1 186.8
60 "Projection Example 2 651.3 747.1 186.8
60 "Projection Example 3 650.0 747.1 186.8
80 "When Projecting Example 1 885.6 996.1 249.0
80 "Projection Example 2 885.6 996.1 249.0
80 "Projection Example 3 882.4 996.1 249.0
100 "When Projecting Example 1 1011.7 1245.0 331.3
100 "when projecting Example 2 1011.9 1245.0 331.3
100 "at projection Example 3 1011.8 1245.0 331.3
As described above, the projection lens that realizes the tilted projection optical system obtained in the present invention can set the shift amount S1 to 20% or more with respect to the vertical size Dv of the image. The ratio D / L0 between the projection screen dimension D (mm) and the projection distance L0 (mm) is 60 inches projection with a screen dimension of 1524 (mm) and a projection distance of 1800 (mm) in the case of a general projection display. The ratio D / L0 is 0.85. Even a shorter one has a projection distance of about 1000 (mm) and this ratio D / L0 is 1.52. However, as described above, the tilt projection optical system of the present invention can be realized even if D / L is 2.0 or more. Thus, in the embodiment, 2.34 can be realized.

  On the other hand, according to the present invention, as shown in FIG. 11, it is possible to realize a projection display apparatus having a plane mirror for turning back an optical path. As a result of the trial production, the distance between the lens arranged at the position closest to the projection plane and the plane mirror is about 150 mm, so L1 shown in FIG. 11 is shortened by about 150 mm from L0. If the set depth is 350 mm, the distance from the projection display apparatus of the present invention to the projection surface is shortened by 500 mm with respect to L0 when the light is turned back by a plane mirror, and a large screen can be obtained with a small installation space. This is a great merit such that the presenter can not see the image light of the projection display device directly.

  Next, regarding the aberration correction mechanism of the projection lens that realizes the tilt projection optical system as an embodiment of the present invention and the specific reading of the lens data, FIG. This will be described using the lens data shown in (b). As a whole, L16 to L12 constitute the third group in order from the projection plane (screen) side with a lens having a three-group configuration, and L16 to L13 are all concave lenses and are telecentric to simultaneously reduce L12 in order to reduce lateral chromatic aberration. Convex lenses using a small number of glass materials are arranged. Further, by arranging L16 at a position not including the optical axis 11 shared by a plurality of lenses constituting the inclined projection optical system as shown in FIG. As a strong aspherical shape that can be controlled independently, it is possible to correct trapezoidal distortion caused by tilted projection and aberrations (particularly higher-order coma and astigmatism) due to super wide angle. At this time, the lens outer shape of L16 does not need to be a circular shape symmetric with respect to the optical axis for the reason described above, and is a rectangle that is substantially equal to the aspect ratio (aspect ratio) of the image display surface effective area or an area through which the image light flux passes. Combined trapezoidal shape. For this reason, there is also an effect of shielding unnecessary light that lowers the imaging performance. Further, since the outer shape of L16 described above is not a circular shape symmetric with respect to the optical axis 11, the size can be reduced. As a result, the inclined projection optical system of the present embodiment is housed in the casing of the projection display apparatus. However, the outer shape of L16 can be accommodated within the maximum width in the screen vertical direction of the surface facing the projection surface, and at the same time the outer shape center of L16 is located above the center line of the surface facing the projection surface of the housing. As a result, the balance in appearance is improved and the design can be greatly improved.

  L11 to L9 constitute a second group, and L11 is a lens having a strong aspherical shape having a weak negative refractive power, and a spherical surface generated by a light beam that passes through a place away from the optical axis and is substantially parallel to the optical axis. Aberrations and low-order coma are corrected, and L10 and L9 share a part of the refractive power of the glass lens projection lens having a positive refractive power, and L9 has a coma as a meniscus shape convex to the projection surface (screen) side. It suppresses the generation of aberrations and astigmatism.

  Finally, L8 to L1 constitute the first group, and the doublet lens of L8 and L7 and the triplet lens of L6 to L4 are given a negative refracting power so as to have stronger telecentricity. Furthermore, L3 is a lens having a strong aspherical shape, and it corrects the annular coma generated by a light beam that passes through a location away from the optical axis and is oblique to the optical axis, so that the entire projection lens can be distorted even when tilted. Suppresses and achieves good focusing performance. The projection lens according to another embodiment of the present invention shown in FIGS. 13 and 14 is obtained by dividing L15 in FIG. 12 into L15 and L16, respectively, to improve the aberration correction capability. The aspherical lens L16 in FIG. In FIG. 14, the effects obtained by simply replacing L17 and the configuration of the projection optical system are the same.

  Next, specific numerical values of the tilted projection optical system described above will be exemplified with reference to FIGS. 25A, 25B, 26A, 26B, and 27A, 27B. While explaining. First, FIG. 12 shows the configuration of the projection optical system according to the present embodiment based on the numerical example shown in FIGS. 25A and 25B. In the XYZ orthogonal coordinates described above, FIG. The structure of is shown. The image projection apparatus according to the present invention can be configured to have an optical path bending mirror (not shown) as shown in FIGS. 1 to 6, but for the sake of explanation, the optical paths shown in FIGS. Explain that there is no folding mirror. The configuration diagram of the projection optical system in FIG. 12 is shown expanded in the Z-axis direction, and this is the same in FIGS.

  The light emitted from the image display surface P0 (shown as a liquid crystal panel in the embodiment) P0 shown below the optical axis 11 in FIG. 12 is a rotationally symmetric surface among the projection lenses including a plurality of lenses. It passes through the first group and the second group which are composed only of lenses having only the lens. Then, it passes through the third group including the rotationally asymmetric aspherical lens L16 with respect to the lens outer shape center and is enlarged and projected on the projection surface.

  Here, the first group and the second group of the projection lens are all composed of a plurality of lenses having a rotationally symmetric refracting surface, and four of the refracting surfaces are rotationally symmetric aspherical surfaces. The others are spherical. The rotationally symmetric aspherical surface used here is expressed by equation (1) in FIG. 25B using a local cylindrical coordinate system for each surface. Here, r is the distance from the optical axis, and Z represents the sag amount of the lens surface shape. C is the curvature at the apex, k is the conic constant, and A to J are coefficients of the power of r.

  FIG. 25A shows the radius of curvature of each surface. In FIG. 25A, 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 FIG. 25A, the inter-surface distance indicates the distance from the apex of the lens surface to the apex of the next lens surface. When a next lens surface is located on the left side in FIG. 25A with respect to a certain lens surface, the inter-surface distance is represented by a positive value, and when located on the right side, it is represented by a negative value. Furthermore, in FIG. 25A, the surface number (9), the surface number (10), the surface number (23), the surface number (24), the surface number (33), and the surface number (34) are rotationally symmetric with respect to the optical axis. In FIG. 25 (a), an aspherical surface is described next to the surface number in the table for easy understanding.

  The coefficients of these six aspheric surfaces are shown in FIG.

    From the table of FIG. 25B, it can be seen that the conic coefficient k is 0 in the present embodiment. Trapezoidal distortion due to oblique incidence occurs extremely large in the direction of oblique incidence, and the amount of distortion is small in the direction perpendicular thereto. Therefore, a significantly different function is required between the direction of oblique incidence and the direction perpendicular thereto, and asymmetrical aberrations are favorably corrected by not using the above-mentioned conic coefficient k that functions rotationally and in all directions. be able to.

  The numerical values shown in the tables of FIGS. 25 (a) and 25 (b) are in the range of 0.59 inches diagonal with a 16 × 9 aspect ratio on the screen of the liquid crystal panel as the video display surface. Describes the values that can be obtained when a light-modulated optical image (dimmed image) is projected on a screen as a projection plane to a diagonal size of 60 inches, 80 inches, and 100 inches. In order to obtain optimum focusing performance, it is preferable to move L15 and L16 in parallel with the optical axis so that the values of the lens intervals (30) and (34) become the surface interval values shown in the lower table of FIG.

  The lens data described in FIGS. 26A and 26B and FIGS. 27A and 27B are also described in the same format.

  FIGS. 16A and 16B show the spot shape of the projection image obtained by enlarging and projecting the lens data described in FIGS. 25A and 25B of Numerical Example 1 to 80 inches, and FIGS. 26A and 26B of Numerical Example 2. FIGS. FIG. 17 shows the spot shape of a projection image enlarged and projected to 80 inches with the lens data described in FIG. 17, and projection projected to 80 inches with the lens data shown in FIGS. 27A and 27B of Numerical Example 3 The spot shape of the image is shown in FIG. In FIG. 16, (0, 3.67), (−6.53, 3.67), (−3.92, 2) in terms of X and Y coordinates on the display screen of the liquid crystal panel as the video display surface. .20), (0.0, 0.0), (0, 0), (−6.53, 0.0), (−3.92, −2.20), (0, −3.67). ) (−5.53, −3.67) (−5.22, −3.67) (−5.22 and 3.67) The spot diagrams of the light beams emitted from 10 points are shown in order from the bottom. The unit of the scale is 5 mm. The horizontal direction of each spot diagram is the X direction on the liquid crystal panel that is the video display surface, and the vertical direction is the Y direction on the liquid crystal panel that is the video display surface. The spot diagrams shown in FIG. 17 and FIG. 18 are also obtained by the light flux from the point of the same value in the X and Y coordinates on the display screen of the liquid crystal panel as the image display surface, and maintain good performance. I understand.

  The embodiment of the tilt projection optical system that realizes the projection display apparatus of the present invention has been described in detail above. In the above example, the light beam emitted from the projection lens is also folded by a plane mirror for folding the optical path and directed toward the liquid crystal panel as the image display surface, but the present invention is limited to this. Needless to say, depending on the position of the projection lens, the above-described plane mirror for folding may be omitted.

  Next, an embodiment of an illumination optical system used in the projection display apparatus of the present invention will be described with reference to FIG. In FIG. 19, the light source 101 includes a lamp 98 and a reflector 99. This lamp 98 is a white lamp of a high-pressure mercury lamp. The reflector 99 has a reflecting surface having a parabolic shape, for example, which is disposed so as to cover the lamp 98 from the rear side, and has a circular or polygonal exit opening. The light emitted from the lamp 98 is reflected by the reflector 99 having a rotating parabolic reflecting surface, is substantially parallel to the optical axis 115, and a substantially parallel light beam is emitted from the light source 101. Light emitted from the light source 101 enters a multi-lens integrator.

  As described above, the multilens integrator 103 includes the first multilens element 103a and the second multilens element 103b. The lens cell shape of the first multi-lens 103a has a rectangular shape substantially similar to the liquid crystal panels 112a, 112b, and 112c when viewed from the direction of the optical axis 115, and a plurality of lens cells are arranged in a matrix. In this way, the light incident from the light source is divided into a plurality of light by a plurality of lens cells, and is efficiently guided so as to pass through the second multi-lens element 103b and the polarization conversion element 104. That is, the first multi-lens element 103a is designed such that the lamp 98 and each lens cell of the second multi-lens element 103b are in an optically conjugate relationship.

  Similarly to the first multi-lens element 103a, the lens cell shape of the second multi-lens element 103b is rectangular when viewed from the direction of the optical axis 115, and a plurality of lens cells are arranged in a matrix. Each of the lens cells constituting the lens element has a lens cell shape of the corresponding first multi-lens element 121 on the liquid crystal panels 122a, 122b, and 122c together with the superimposing lenses 108a, 108b, and 108c. Project (map) to. In this process, the light from the second multi-lens element 103b is aligned in a predetermined polarization direction by the action of the polarization conversion element 104. At the same time, the projected images by the lens cells of the first multi-lens element 103a are superimposed by the action of the superimposing lenses 108a, 108b, 108c, respectively, so that the light amount distribution on the corresponding liquid crystal panels 112a, 112b, 112c. Becomes uniform.

  Among the plurality of lenses constituting the tilted projection optical system of the present invention, the lens disposed at the position closest to the projection plane is made of plastic, and the effective area in the image vertical direction through which the light beam passes is the most among the optical axes of the plurality of lenses. This plastic lens is arranged at a position that does not include the optical axis shared by many lenses, and this plastic lens is a shape obtained by cutting out a part of an aspherical shape symmetrical to the optical axes shared by the largest number of lenses constituting the projection optical system And As shown in FIG. 20, the mold is processed using a multi-axis machine, and the mold as the workpiece is rotated and cut with a cutting tool as shown in FIG. As shown in Fig. 2 (b), there is a method of processing the necessary mold shape while fixing the work and rotating the cutting tool as shown in Fig. 2 (b). If it is going to obtain, cutting time will need about 10 to 20 times. The method (b) is superior to the processing of a rotationally asymmetric free-form surface, and the method (a) is suitable for processing a rotationally symmetric aspherical shape in a short time.

  Among the plurality of lenses constituting the tilted projection optical system of the present invention, the lens disposed at the position closest to the projection plane is made of plastic, and the image vertical effective area through which the light beam passes is the optical axis of the plurality of lenses described above. This plastic lens is arranged at a position that does not include the optical axis shared by the largest number of lenses, and this plastic lens cuts out a part of the aspherical shape symmetrical to the optical axis shared by the largest number of lenses constituting the projection optical system. As shown in FIG. 20 (a), a mold corresponding to a desired lens shape is rotated by rotating a mold as a workpiece with a multi-axis machining machine and cutting with a cutting tool. A method for obtaining the mold shape can be adopted, and the mold can be machined in a short machining time, thereby reducing the development cost.

  At this time, for example, when a die is machined with the C-axis of the multi-axis machine shown in FIG. 20A as the rotation axis, according to the present invention, a plurality of machines can be machined simultaneously. In the case of machining, if two dies (workpieces) are arranged symmetrically with respect to the rotation axis as shown in FIG. 22, it is possible to obtain a desired die shape with good cutting balance at the time of machining with high accuracy. Further, FIG. 23 shows the optimum arrangement when processing four dies simultaneously. However, even when odd numbers are simultaneously used, the rotation angle (360 degrees) is shifted by an angle divided by the number of dies to be processed simultaneously. Needless to say, the same effect can be obtained.

  In the tilted projection optical system of the present invention described above, the outer shape of the lens disposed at the position closest to the projection surface is a rectangular shape as shown in FIG. 24, for example. At this time, the outer shape of the lens effective surface is based on the outer shape. The lens surface shape is asymmetric with respect to the center axis, but the aspherical surface is symmetric with respect to the optical axis shared by the most numerous lenses constituting the above-described tilted projection optical system.

  DESCRIPTION OF SYMBOLS 1a ... Upper housing | casing 1 of a projection type video display apparatus 1, ... Planar mirror fixed frame, 3 ... Image light beam, 4 ... Fixed part, 5 ... Plane mirror rotating mechanism, 6 ... Fixed part 1, 7 ... Fixed part 2, 8 DESCRIPTION OF SYMBOLS ... Planar mirror moving mechanism, 9 ... Lower housing of projection display apparatus, 11 ... Optical axis, R1 ... Upper limit light, R2 ... Lower limit light, [theta] 1 ... Elevation angle of mirror, [theta] 2 ... Elevation angle of projection display apparatus, 1b ... Upper housing 2, L17 ... Plastic lens, L1 ... Lens, L2 ... Lens, L3 ... Lens, L4 ... Lens, L5 ... Lens, L6 ... Lens, L7 ... Lens, L8 ... Lens, L9 Lens, L10 ... Lens, L11 ... Lens, L12 ... Lens, L13 ... Lens, L14 ... Lens, L15 ... Lens, L16 ... Lens, 98 ... Tube, 99 ... Reflector, 101 ... Light source, 102 ... UV cut filter, 1 03 ... multi-lens integrator 103a ... first multi-lens element 103b ... second multi-lens element 104 ... polarization conversion element 115 ... optical axis 116a, 116b, 116c, 116d ... mirror, 117a, 117b ... Dichroic mirror, 108a, 108b, 108c ... superimposing lens, 105, 109, 110 ... field lens.

Claims (23)

In an inclined projection optical system that projects an image displayed on the image display surface obliquely enlarged on the projection surface,
The tilted projection optical system is composed of a plurality of lenses, and the lens arranged at the position closest to the projection plane shares the effective image vertical direction area through which the light beam passes with the largest number of lenses among the optical axes of the plurality of lenses. The distance between the lens disposed at a position that does not include the optical axis and having an axially asymmetric shape with respect to the optical axis and the lens disposed at the position closest to the projection plane is L, and is projected. An inclined projection optical system satisfying the following relational expression when the diagonal dimension of the screen is D.
2.0 <D / L   2. The tilt projection optical system according to claim 1, wherein an optical path folding plane mirror is disposed between a lens disposed at a position closest to the projection plane and the projection plane, and is disposed at a position closest to the projection plane. The upper end of the effective area in the screen vertical direction of the lens is located above the lower end of the effective area in the vertical direction of the plane mirror, and the plane mirror has a predetermined elevation angle with respect to the optical axis shared by the most lenses. The inclined projection optical system according to claim 1, wherein: 3. The tilt projection optical system according to claim 2, wherein the flat mirror has a rotation adjustment mechanism that has a predetermined elevation angle with respect to an optical axis shared by the most numerous lenses and that can change the elevation angle. The tilted projection optical system according to claim 2, wherein:   4. The tilt projection optical system according to claim 2 or 3, further comprising a plane mirror moving mechanism that enables the plane mirror to move along an optical axis shared by the largest number of lenses. An inclined projection optical system. An inclined projection optical system that projects an image displayed on an image display surface obliquely on the projection surface, and the inclined projection optical system is composed of a plurality of lenses, and the lens disposed closest to the projection surface is: The image vertical effective region through which the light beam passes is arranged at a position not including the optical axis shared by the largest number of lenses among the optical axes of the plurality of lenses, and the shape thereof is relative to the central axis of the lens effective surface. Consists of a lens having an axially asymmetric shape,
An inclined projection optical system, wherein the lens arranged closest to the projection plane is a shape obtained by cutting out a part of an aspheric shape symmetrical to the optical axis shared by the largest number of lenses.   6. The tilt projection optical system according to claim 5, wherein a plane mirror that turns the optical path is disposed between a lens disposed at a position closest to the projection plane and the projection plane, and is disposed at a position closest to the projection plane. The upper end of the effective area in the screen vertical direction of the lens is positioned above the lower end of the effective area in the vertical direction of the plane mirror, and the plane mirror has a predetermined elevation angle with respect to the optical axis shared by the most lenses. The tilted projection optical system according to claim 5, comprising:   7. The tilt projection optical system according to claim 6, wherein the flat mirror has a rotation adjustment mechanism that has a predetermined elevation angle with respect to an optical axis shared by the largest number of lenses and that can change the elevation angle. The tilted projection optical system according to claim 6, wherein   8. The tilt projection optical system according to claim 6 or 7, further comprising a plane mirror moving mechanism that enables the plane mirror to move along an optical axis shared by the most numerous lenses. An inclined projection optical system.   A projection-type image display device having an inclined projection optical system that projects an image displayed on an image display surface in an obliquely enlarged manner onto the projection surface, and the inclined projection optical system includes a plurality of lenses. The lens arranged at the closest position to the lens is arranged at a position where the effective image vertical direction area through which the light beam passes does not include the optical axis shared by the largest number of lenses among the optical axes of the plurality of lenses. A projection-type image display apparatus, wherein the projection-type image display apparatus is housed in a maximum width in a vertical direction of a screen on a surface facing a projection surface of a housing forming the display-type image display device. A projection-type image display device having an inclined projection optical system that projects an image displayed on an image display surface in an obliquely enlarged manner onto the projection surface, and the inclined projection optical system includes a plurality of lenses. The lens arranged at the closest position to the lens is arranged at a position where the effective image vertical direction area through which the light beam passes does not include the optical axis shared by the largest number of lenses among the optical axes of the plurality of lenses. An optical path folding plane mirror is arranged between the lens arranged closest to the surface and the projection surface,
When the plane mirror is arranged at a predetermined angle with respect to the optical axis shared by the largest number of lenses, the enlarged image obtained by the image light beam folded by the plane mirror is in the direction of the image display surface. A projection-type image display device configured to obtain an enlarged image. A projection-type image display device having an inclined projection optical system that projects an image displayed on an image display surface in an obliquely enlarged manner onto the projection surface, and the inclined projection optical system includes a plurality of lenses. The lens arranged at the closest position to the lens is arranged at a position where the effective image vertical direction area through which the light beam passes does not include the optical axis shared by the largest number of lenses among the optical axes of the plurality of lenses. An optical path folding plane mirror is disposed between a lens disposed at a position closest to the surface and the projection plane, and the plane mirror is capable of changing the angle with respect to the optical axis shared by the most numerous lenses. Provided,
In the first state in which the plane mirror is disposed at a predetermined angle with respect to the optical axis shared by the largest number of lenses, the enlarged image obtained by the image light beam folded by the plane mirror is displayed on the image display. In the second state in which the flat mirror is housed in the projection display device, the optical axis shared by the largest number of lenses among the optical axes of the plurality of lenses is extended. A projection-type image display device configured to obtain an enlarged image in a specified direction.   12. The projection display apparatus according to claim 10, wherein the inclined projection optical system includes an optical path folding plane mirror between a lens disposed at a position closest to the projection plane and the projection plane. And a projection-type image display device characterized in that the upper end of the effective area in the screen vertical direction of the lens arranged closest to the projection plane is located above the lower end of the effective area in the vertical direction of the plane mirror. . The projection display apparatus according to any one of claims 10 and 12,
A projection-type image display apparatus, comprising: a moving mechanism that enables the flat mirror disposed in the tilted projection optical system to be moved along an optical axis shared by the largest number of lenses. The projection display apparatus according to any one of claims 10 and 13,
The flat mirror disposed in the tilted projection optical system is provided with a rotation adjusting mechanism capable of changing the angle with respect to the optical axis shared by the largest number of lenses, and means for detecting the rotation angle of the flat mirror And a projection type image display device having an image correction function for automatically correcting screen distortion of the projection image according to the detected rotation angle.   In a projection display apparatus, an inclined projection optical system that projects an image displayed on an image display surface obliquely on the projection surface is projected, and the inclined projection optical system includes a plurality of lenses and is closest to the projection surface The lens arranged at a position is arranged at a position where an image vertical direction effective region through which a light beam passes does not include an optical axis shared by the largest number of lenses among the optical axes of the plurality of lenses, and the shape thereof is a lens. A lens that is configured by a lens having an axially asymmetric shape with respect to the central axis of the effective surface and that is disposed closest to the projection surface is an aspherical surface that is symmetrical with respect to the optical axis shared by the most polyhedral lens. A projection-type image display apparatus using an inclined projection optical system, characterized in that a part of the shape is cut out.   16. The projection type image display device according to claim 15, wherein the inclined projection optical system magnifies and projects an image displayed on the image display surface onto the projection surface, and a lens disposed at a position closest to the projection surface; A plane mirror for turning the optical path is arranged between the projection planes, and the upper end of the effective area in the screen vertical direction of the lens arranged closest to the projection plane is located above the lower end of the effective area in the vertical direction of the plane mirror. The flat mirror has a predetermined elevation angle with respect to an optical axis shared by the largest number of lenses.   16. The projection type image display device according to claim 15, wherein the inclined projection optical system magnifies and projects an image displayed on the image display surface onto the projection surface, and a lens disposed at a position closest to the projection surface; A plane mirror for turning the optical path is arranged between the projection planes, and the upper end of the effective area in the screen vertical direction of the lens arranged closest to the projection plane is located above the lower end of the effective area in the vertical direction of the plane mirror. And an inclined projection optical system characterized in that the plane mirror has a rotation adjustment mechanism that has a predetermined elevation angle with respect to the optical axis shared by the largest number of lenses and that can change the elevation angle. A projection-type image display device comprising: The projection display apparatus according to any one of claims 15 to 17,
The flat mirror disposed in the tilted projection optical system is provided with a rotation adjusting mechanism capable of changing the angle with respect to the optical axis shared by the largest number of lenses, and means for detecting the rotation angle of the flat mirror And a projection type image display device having an image correction function for automatically correcting screen distortion of the projection image according to the detected rotation angle.   17. The tilt projection optical system according to claim 15 and claim 16, further comprising a plane mirror moving mechanism that allows the plane mirror to move along an optical axis shared by the largest number of lenses. A projection optical apparatus comprising an inclined projection optical system. A projection-type image display device having an inclined projection optical system that projects an image displayed on an image display surface in an obliquely enlarged manner onto the projection surface, and the inclined projection optical system includes a plurality of lenses. The lens arranged at the closest position to the lens is arranged at a position where the effective image vertical direction area through which the light beam passes does not include the optical axis shared by the largest number of lenses among the optical axes of the plurality of lenses. An optical path folding plane mirror is arranged between the lens arranged closest to the surface and the projection surface,
When the plane mirror is disposed at a predetermined angle θ1 with respect to the optical axis shared by the most lenses, the enlarged image obtained by the image light beam folded by the plane mirror is in the direction of the image display surface. The projection type image display device is disposed at an angle of θ2 with respect to a reference plane substantially perpendicular to the enlarged image, and the θ1 and θ2 satisfy the following relationship: Projection-type image display device.
1.5 ≦ θ2 / θ1 ≦ 2.5   A plastic lens for use in an inclined projection optical system configured by a plurality of lenses and configured to project an image displayed on an image display surface in an enlarged manner on the projection surface, the plastic lens being disposed at a position closest to the projection surface; The effective region in the image vertical direction through which the light beam passes is arranged at a position not including the optical axis shared by the largest number of lenses among the optical axes of the plurality of lenses, and the plastic lens is shared by the largest number of lenses. A plurality of molding dies having a shape obtained by cutting out a part of an aspherical shape symmetrical to the optical axis and symmetric with respect to the optical axis shared by the largest number of lenses when performing the molding die processing. A mold processing method characterized by arranging and cutting.   An inclined projection optical system using at least one plastic lens molded using a mold cut by the processing method according to claim 21.   A projection optical apparatus comprising an inclined projection optical system using at least one plastic lens molded using a mold cut by the processing method according to claim 21.

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