JP5039399B2 - Lens system - Google Patents

Description

  The present invention relates to a lens system including a non-circular lens.

  Patent Document 1 describes a zoom lens having a first lens group having a positive refractive power and a second lens group having a negative refractive power in order from the object side to the image plane side. The first lens group has a meniscus lens formed in an oval shape in which one end and the other end corresponding to the longitudinal direction of a horizontally long image to be obtained are cut.

  Patent Document 2 describes an imaging device including an imaging element and a plurality of lenses including a non-circular lens. The imaging element has a rectangular light receiving surface, and the non-circular lens has a shape in which a portion that does not contribute to image formation from the circular lens to the light receiving surface is removed. In other words, the non-circular lens has a shape in which the straight portion of the cut portion and the long side of the light receiving surface are substantially parallel, and includes two straight portions cut in parallel.

Thus, it is required to make the lens system compact for the purpose of mounting on a thin portable terminal. Therefore, it is known to cut a portion of a circular lens that does not contribute to image formation in accordance with a rectangular light receiving surface or a horizontally long image to be obtained. Patent Document 2 further includes a zoom lens having a three-group configuration having a negative-positive retrofocus configuration from the object side, and has a function of bending the optical axis in the vertical direction in the middle of the zoom lens in response to a request for thinness. Is described. In the retrofocus configuration, the diameter of the circular lens of the lens disposed closest to the subject is increased. For this reason, it is described that the surface area of the lens can be reduced when the lens is a non-circular lens and the straight portion of the D-cut portion is parallel to the long side of the rectangular light receiving surface.
JP 2005-78038 A JP 2006-267391 A JP 2005-234275 A

  A rear projector is known as a means for displaying an image. Patent Document 3 describes a rear projector that includes an electro-optical unit that outputs an optical image corresponding to an electric signal, and a reflecting mirror that projects the optical image output from the electro-optical unit onto a transmissive screen. . In this type of rear projector (rear professional television), an optical image is output at an acute angle from the electro-optic unit to the rear reflecting mirror by a projection lens.

  In this type of rear projector, in order to reduce the depth, a wide-angle lens system is employed, and further, the light is bent and output at a more acute angle. In a bright lens system with a wide angle and a small F number, the lens diameter increases. For this reason, when the optical path is bent at an acute angle, the lens arranged in the optical path before being bent interferes with the lens arranged in the optical path after being bent, or the lens is eroded in one or both of the optical paths. put out. Therefore, it is difficult to realize a lens system that employs a lens having a large diameter and bends the optical path at an acute angle.

One aspect of the present invention is an optical element for changing an angle of an optical path between a first direction and a second direction, an optical element disposed adjacent to the first direction of the optical element, and at least one lens comprising: A first lens group arranged along the first optical axis; and a second lens group arranged in the second direction of the optical element and having at least one lens arranged along the second optical axis. A lens system. Furthermore, the optical element is disposed such that the first optical axis and the second optical axis form an acute angle, and the first lens group includes a non-circular lens disposed adjacent to the optical element. The non-circular lens, the side is concave optical element, the whole including the portion where one portion is cut on the circumference is D-shaped, arcuate-shaped side is concave cut portion is an optical element the a cut part including position, the arcuate shape, so that it is perpendicular to the first optical axis and a second plane including the optical axis, are combined in the lens system. Further, the optical path from the second lens group to the optical element is shifted in the direction of the cut portion with respect to the second optical axis, and a part of the optical path is assumed when the non-circular lens is a circular lens. The optical path from the optical element to the first lens group passing through the inside of the arch shape is shifted to the side opposite to the portion cut with respect to the first optical axis.

  In this lens system, the inside of the arcuate shape can be used as a part of the optical path of the second lens group and / or the optical path from the second lens group to the optical element. Therefore, if all the lenses included in the first lens group and the second lens group are circular, the lenses may interfere with each other, or one group of lenses may affect light rays passing through the other group. Even if it is an arrangement, this lens system can be used. For this reason, it is possible to arrange the lens system including the optical path for bending the light beam in a more compact manner, and it is possible to make the bending angle of the lens system including the lens having a large diameter even more acute. That is, this lens system is suitable for a lens system in which the optical elements are arranged such that the first optical axis and the second optical axis form an acute angle. Furthermore, it is suitable for a retrofocus type lens system in which the first lens group has a negative refractive power and the second lens group has a positive refractive power.

  In this lens system, it is desirable that the arcuate shape of the non-circular lens is combined so as to be perpendicular to the plane including the first optical axis and the second optical axis. The space opened by the arched shape of the lens included in the first lens group can be effectively used by the optical path in the second lens group and / or the optical path from the second lens group to the optical element. The first lens group may include a plurality of non-circular lenses.

In the lens system in which the angle is changed so that the first direction and the second direction form an acute angle by the optical element for angle conversion, the non-circular lens has a D-shape and is centered on a portion shifted from the optical axis. It is possible to arrange the lens system so that the light beam passes through, and a larger arch shape can be formed. For this reason, the first optical axis and the second optical axis can be bent at an acute angle.

  The optical element for angle conversion may be a prism. However, in this lens system, both ends of the arcuate shape of the non-circular lens of the first lens group protrude into the space from the second lens group to the optical element. In order to avoid mechanical interference, it is necessary to process one or both into an appropriate shape. Therefore, it is preferable to employ a reflection mirror as the optical element for angle conversion of this lens system.

Another aspect of the present invention is a lens unit including a lens system, a first holder that holds the first lens group, and a second holder that holds at least the second lens group. The first holder includes an arched structure having a concave on the side of the optical element. The first holder is combined with the second holder so that the arcuate structure is not parallel to the plane including the first optical axis and the second optical axis. The inside of the arched structure can be used for the optical path of the second lens group and / or a part of the optical path from the second lens group to the optical element. The first holder, the second holder, arched structure are combined so as to be perpendicular to the first optical axis and a second plane including the optical axis.

  Moreover, when the inner side of the arch-shaped structure of the first holder faces the second holder, a part of the second holder passes through, and interference between the holders can be prevented. Therefore, it is possible to provide a lens unit that houses a lens system in which the first optical axis and the second optical axis are bent at an acute angle.

  This lens system can be combined with a wide variety of optical devices including projectors and imaging devices. Either the first lens group or the second lens group is disposed on the object side or the screen side. In addition to the first lens group, the second lens group may be disposed adjacent to the optical element and may include a non-circular lens including the arched shape described above.

The lens system of the present invention includes an optical element for changing the angle of the optical path between a first direction and a second direction, an optical element disposed adjacent to the first direction of the optical element, and at least one lens comprising A first lens group arranged along the first optical axis; and a second lens group arranged in the second direction of the optical element and having at least one lens arranged along the second optical axis. The optical system is a lens system in which the first optical axis and the second optical axis are arranged so as to form an acute angle, and the cut portion of the non-circular lens constitutes a part of the optical path. That is, the first lens group of this lens system includes a non-circular lens arranged adjacent to the optical element, and the non-circular lens is concave on the side of the optical element and at least one place on the circumference is cut. The cut portion forms a part of the optical path of the second lens group and / or the optical path from the second lens group to the optical element.

  Still another aspect of the present invention is a projector having the above lens system and a light modulation device for generating an image to be projected through the lens system. When the first lens group is disposed on the screen side and the second lens group is disposed on the light modulation device side, the light modulation device is disposed at a position optically shifted with respect to the second optical axis. It is desirable that It is possible to arrange the projector so that the light beam passes around a portion shifted from the optical axis of the lens included in the first lens group, and a larger arch shape can be formed. For this reason, the first optical axis and the second optical axis can be bent at an acute angle.

  For this reason, in a projector having a mirror that reflects light output from the lens system in the direction of the screen, for example, a rear projector, the depth can be reduced.

  One of the other different aspects of the present invention is an imaging apparatus including the lens system described above and an imaging device for capturing an image via the lens system. The inside of the arcuate shape of the non-circular lens included in the first lens group can be used as a part of the optical path of the second lens group and / or the optical path from the second lens group to the optical element, and more compact. Can be provided.

  FIG. 1 shows an embodiment of a rear projector. The rear projector 1 includes a transmissive screen 2 disposed on the front surface of a housing 9, an image generation device 5 that outputs a light beam (projection light) 3 that is modulated so as to form an image on the screen 2, and an image The lens unit 60 including the lens system 50 for outputting the projection light 3 from the generation device 5 and the projection light 3 output from the lens system 50 are arranged on the rear surface of the housing 9 so as to reflect in the direction of the screen 2. The mirror 4 is provided. The image generation device 5 includes an illumination device 6 that divides and outputs illumination light of different colors, and a light modulation device 7 that generates projection light 3 by modulating the illumination light of each color according to image data. An example of the illuminating device 6 is a device including a light source that outputs white light and a color filter (color wheel) for time-dividing the white light into each color. Another example of the illumination device 6 is to generate and output light of each color from white light by a dichroic mirror or the like. Still another example of the lighting device 6 is a device including a plurality of LED light sources that output light of different colors.

  An example of the light modulation device (light valve) 7 is a digital mirror device (DMD), and the DMD includes a plurality of mirror elements that can each represent on / off pixels by changing an angle. Another example of the light modulation device 7 is a transmissive or reflective liquid crystal device. The image generation device 5 includes one or more light modulation devices 7 and generates projection light 3 for displaying a color image on the screen 2. The image generating device 5 further includes other components such as a mirror 8 for reflecting the illumination light.

  In the rear projector 1, image data for generating the projection light 3 in the image generation device 5 is supplied from an external host device such as a video playback device, a DVD player, a TV tuner, or a personal computer. Further, the rear projector 1 may incorporate an image data generation device such as a TV tuner and / or a DVD player. Therefore, the rear projector 1 may be called by another name such as a rear professional television.

  In the rear projector 1, the projection light 3 output forward from the light modulation device 7 of the image generation device 5 is output to the rear mirror 4 by the lens system 50. The lens system 50 includes an optical element that bends the optical path backward at an acute angle, and the depth of the housing 9 can be reduced by making the bending angle (smaller angle) θ of the optical path an acute angle. Therefore, the rear projector 1 having a large display screen and being thin and compact can be provided. That is, as shown by a broken line in FIG. 1, by laying the projection light 3 output from the lens system 50, the mirror 4 can be disposed forward from the position 4 ′, and the housing 9 becomes thin.

  FIG. 2 shows a schematic configuration of the lens unit 60 including the lens system 50 in a sectional view. The cross section 59 is a surface including a first optical axis 19 and a second optical axis 29 described later. The lens system 50 includes an optical element 30 for changing the angle of the optical path of the projection light 3. The optical element 30 has an optical path of the projection light 3 between a first direction (screen side) 51 facing the screen 2 via the mirror 4 and a second direction (device side) 52 of the light modulation device 7. Change between. In the lens system 50, a reflection mirror is employed as the optical element 30. The lens system 50 includes a reflecting mirror 30, a first lens group 10 that is disposed adjacent to the first direction 51 of the reflecting mirror 30, and has a negative overall refractive power, and a second direction 52. The second lens group 20 is disposed adjacently and has a positive refractive power as a whole. Therefore, the lens system 50 is a retrofocus type lens system in which a negative-positive lens group is arranged from the screen 2 side. The first lens group 10 includes three lenses 11 to 13, and these lenses 11 to 13 are arranged along the first optical axis 19 from the screen 2 side (mirror 4 side) of the reflection mirror 30. It is arranged side by side in order. The second lens group 20 includes six lenses 21 to 26, and these lenses 21 to 26 are arranged in order from the reflection mirror 30 side to the device 7 side along the second optical axis 29. Has been placed.

  The lens 11 on the most screen side of the first lens group 10 is a negative meniscus lens that is convex on the screen side, that is, is concave on the reflection mirror 30 side, and the second light with respect to the first optical axis 19. A part 11c on the side of the shaft 29 is cut, and the whole is a D-shaped non-circular lens. The next lens 12 is also a negative meniscus lens convex on the screen side, that is, concave on the reflection mirror 30 side, and a part 12c on the second optical axis 29 side with respect to the first optical axis 19 is A non-circular lens that is cut and entirely D-shaped. The lens 13 closest to the reflecting mirror 30 in the first lens group 10 is a biconcave negative lens, and a part 13c on the second optical axis 29 side with respect to the first optical axis 19 is cut. The whole is a D-shaped non-circular lens.

  The lens 21 closest to the reflection mirror 30 in the second lens group 20 is a biconvex positive lens, and the next lens 22 is a positive meniscus lens convex toward the reflection mirror 30. The next lens 23 is a positive meniscus lens that is concave on the reflection mirror 30 side, and a stop S is disposed on the reflection mirror 30 side of the lens 23. Further, the next lens 24 is a positive meniscus lens convex toward the reflection mirror 30, and the next lens 25 is a biconvex positive lens. The lens 26 closest to the light modulation device 7 is also a biconvex positive lens.

  The lens unit 60 includes a first holder (lens frame) 61 for holding the lenses 11 to 13 included in the first lens group 10 along the first optical axis 19, and a second lens group 20. A second holder (lens barrel main body) 62 for holding the included lenses 21 to 26 along the second optical axis 29 is provided. The second holder 62 holds the reflecting mirror 30 at a predetermined angle. When the first holder 61 is attached to the second holder 62, the first light of the first lens group 10 is retained. The angle θ formed by the axis 19 and the second optical axis 29 of the second lens group 20 is arranged to be an acute angle.

  The lens unit 60 further includes a mask 63 that covers the outer peripheral portion of the surface of the lens 11 closest to the screen. A lens barrel 65 that supports the lenses 21, 22, and 23 and a lens support frame 66 that supports the lenses 24, 25, and 26 are attached to the barrel main body 62 that is the second holder. Focus adjustment can be performed by moving the lens support frame 66 back and forth with respect to the lens barrel 65 along the second optical axis 29.

  FIG. 3 shows the appearance of the lens unit 60. The first lens holder 61 is attached so as to form an acute angle with respect to the second lens holder 62, and a substantially rectangular opening 64 by a mask 63 that is an output port of projection light is a lens 26 that is an input port of projection light. On the other hand, it is oriented in an acute direction.

  FIG. 4 shows how the first lens holder 61 and the second lens holder 62 are assembled. Further, FIG. 5 shows a developed state in which the first lens group 10 is housed in the first lens holder 61. As shown in FIG. 5, the non-circular lens 13 disposed adjacent to the reflecting mirror 30 in the first lens group 10 is a negative lens having a concave on the reflecting mirror 30 side, and one place on the circumference is A cut portion 13c is included. The cut portion 13c includes an arch-shaped shape 13a having a concave on the reflection mirror 30 side. The lens 13 is held by the first lens holder 61, and the cut portion (surface) 13 c including the arch-shaped shape 13 a is opposed to the surface 59 including the first optical axis 19 and the second optical axis 29. Are combined to be vertical.

  As shown in FIGS. 6 and 7, the first lens holder 61 includes an arch-shaped structure portion 61 a in order to hold the arch-shaped shape 13 a portion of the lens 13. FIG. 6 is a view showing the first lens holder 61 from the reflection mirror 30 side. FIG. 7 is a view in which a part of the lens unit 60 is omitted in order to show the position of the arch-shaped structural portion 61a in a state where the lens holders 61 and 62 are combined. The inner side of the arch-shaped structure portion 61a of the first lens holder 61, that is, the inner side of the arch-shaped shape 13a of the lens 13 is a light beam that reaches the reflection mirror 30 from the second lens group 20 as shown in FIG. A region through which 28 passes, that is, a part of the optical path 27 is formed.

  As shown in FIG. 5, the non-circular lens 12 in the middle of the first lens group 10 is a meniscus lens having a concave on the reflection mirror 30 side, and a portion 12c cut at one place on the circumference is provided. Including. The cut portion 12c includes an arch-shaped shape 12a having a concave on the reflection mirror 30 side. This lens 12 is also held by the first lens holder 61, and the cut portion (surface) 12 c including the arch-shaped shape 12 a is formed on the surface 59 including the first optical axis 19 and the second optical axis 29. They are combined so that they are perpendicular to each other. As shown in FIGS. 6 and 7, the first lens holder 61 includes an arch-shaped structure portion 61 b in order to hold the arch-shaped shape 12 a portion of the lens 12. The inner side of the arch-shaped structure portion 61 b of the first lens holder 61, that is, the inner side of the arch-shaped shape 12 a of the lens 12, as shown in FIG. 2, the light flux reaching the reflection mirror 30 from the second lens group 20. A region through which 28 passes, that is, a part of the optical path 27 is formed.

  As shown in FIG. 5, the non-circular lens 11 on the most screen side of the first lens group 10 is a meniscus lens having a concave on the reflection mirror 30 side, and one portion on the circumference thereof is cut off. 11c is included. The cut portion 11c includes an arch-shaped shape 11a having a concave on the reflection mirror 30 side. This lens 11 is also held by the first lens holder 61. The lens 11 is fixed to the first lens holder 61 from the outside (the screen 2 side via the mirror 4) by a lens mounting plate 69, and a lens mask 63 having an opening 64 is attached to the outside thereof. . In this lens 11, the first lens holder 61 is attached to the second lens holder 62, so that the cut portion (surface) 11 c including the arch-shaped shape 11 a becomes the first optical axis 19 and the second optical axis 19. They are combined so as to be perpendicular to the surface 59 including the optical axis 29.

  As shown in FIG. 6, the first lens holder 61 includes an arch-shaped structure portion 61 c in order to hold the arch-shaped shape 11 a portion of the lens 11. The inside of the arch-shaped structure portion 61c of the first lens holder 61, that is, the inside of the arch-shaped shape 11a of the lens 11 is a portion through which a part of the second lens holder 62 passes as shown in FIG. It becomes. Therefore, the arch-shaped structural portion 61c prevents the holders 61 and 62 from interfering when the optical path is bent at an acute angle in the lens unit 60.

  As described above, the lens unit 60 includes the lens system 50, and the lens system 50 includes an optical element (reflection mirror) 30 for changing the angle of the optical path between the first direction 51 and the second direction 52. The first lens group 10 disposed adjacent to the first direction 51 of the reflection mirror 30 and the second lens group 20 disposed in the second direction 52 are included. Further, the reflection mirror 30 is arranged such that the second optical axis 29 through which the second lens group 20 passes is an acute angle with respect to the first optical axis 19 through the first lens group 10.

  The first lens group 10 includes a non-circular lens 13 disposed adjacent to the reflecting mirror 30 and non-circular lenses 12 and 11 disposed outside thereof. These non-circular lenses 11 to 13 include portions 11c to 13c that are concave on the side of the optical element and are cut at least at one place on the circumference, and the cut portion has an arch shape that is concave on the side of the optical element. The arch-shaped shapes 11a to 13a are arranged so as to be perpendicular to the surface 59 including the first optical axis 19 and the second optical axis 29. If the arch-shaped shapes 11a to 13a are arranged so as not to be parallel to the surface 59, the inside of the arch-shaped shapes 11a to 13a can be used as a part of the optical path 27, or the second lens holder. It can be used as a region for avoiding interference with 62. When the arch-shaped shapes 11a to 13a are arranged perpendicular to the surface 59, the projected area of the arch-shaped shapes 11a to 13a with respect to the optical path 27 becomes the largest, so that the space opened by the arch-shaped shapes 11a to 13a is efficiently used. It can be used as a part of the optical path 27.

  Therefore, if all the lenses 11 to 13 included in the first lens group 10 are circular, the lenses interfere with each other, or the lens of one group affects the light rays passing through the other group. Even if it exists, if it is this lens system 50, it is employable. For example, in FIG. 8, a virtual region occupied when the lenses 11 to 13 are circular lenses is indicated by broken lines. The virtual portion 11 ′ of the lens 11 protrudes to a position where it interferes with the lens 23 of the second lens group 20. The virtual portion 12 ′ of the lens 12 protrudes to a position where it interferes with the lens 22, and affects the light flux 28 that passes through the second lens group 20. Further, the virtual portion 13 ′ of the lens 13 protrudes to a position where it interferes with the lens 21, and affects the light beam 28 that reaches the reflection mirror 30 from the second lens group 20.

  On the other hand, in the lens system 50, by employing the non-circular lenses 11 to 13, the interference with the lens included in the second lens group 20 as described above, and the light beam passing through the second lens group 20 is achieved. 28 can be prevented. Further, if the non-circular lenses 11 to 13 are convex lenses on the reflection mirror 30 side, even if interference with the respective cut virtual portions 11 ′ to 13 ′ is avoided, the second portion is the convex portion. There is a possibility of interfering with the lens of the lens group 20 or the light beam 28. If the non-circular lenses 11 to 13 are concave lenses on the side of the reflection mirror 30, an arrangement is employed to avoid interference with the lenses of the second lens group 20 and the light beam 28 in the cut virtual portions 11 ′ to 13 ′. it can.

  Furthermore, in this lens system 50, the space for arranging the lenses of the second lens group 20 is the space inside the arch-shaped shapes 11a to 13a appearing in the cut portions 11c to 13c of the lenses 11 to 13. The second lens group 20 is used as a part of an optical path 27 through which a light beam 28 reaching the reflection mirror 30 passes from the second lens group 20. Therefore, both ends of the arch-shaped shapes 11 a to 13 a protrude into the second lens holder 62, or the arch-shaped structural portions 61 a and 61 b of the first lens holder 61 are inside the second lens holder 62. Arrangement that protrudes into the can be adopted. Further, it is possible to employ an arrangement in which both ends of the arch-shaped structural portion 61 c of the first lens holder 61 straddle the outside of the second lens holder 62. Therefore, the first lens group 10 and the second lens group 20 can be combined in a more compact manner and so that the optical axes intersect at an acute angle.

  In addition, a lens having a large diameter can be adopted as a lens constituting the first lens group 10, and it is a bright lens system having a wide angle and a small F number, and the bending angle θ of the internal optical path is further acute. Can provide a lens system. Therefore, like the lens system 50 of this example, the first lens group 10 on the screen side has a negative refractive power, and the device 7 side has a positive refractive power. It is possible to provide a lens system in which the bending angle θ of the internal optical path becomes even sharper. Therefore, by employing this lens system 50, the depth of the rear projector 1 shown in FIG. 1 can be reduced.

  In the lens system 50 in which the angle is changed so that the first direction 51 and the second direction 52 form an acute angle by the reflection mirror 30 for angle conversion, the outside of the non-circular lenses 11 to 13, that is, the first optical axis. 19, the cut portions 11 c to 13 c can be enlarged by making more use of the region opposite to the second optical axis 29. Therefore, the angle θ at which the optical path is bent by the reflecting mirror 30 can be further increased. For this reason, the non-circular lenses 11 to 13 of the lens system 50 have a D-shaped asymmetric shape in which only the inner side is cut. Further, the light modulation device 7 is arranged with its center shifted from the second optical axis 29 so that the light beam 18 passes around the portion shifted from the first optical axis 19. In this example, the light modulation device 7 is arranged in a state shifted to the outside (lower side) of the second optical axis 29, and the light beam 18 reflected by the reflecting mirror 30 is shifted to the outside of the first optical axis 19. In this state, it passes through the lenses 11 to 13 of the first lens group 10.

  In this lens system 50, the optical element for angle conversion is the reflection mirror 30, but may be a prism. However, in this lens system 50, both ends of the arcuate shape 13 a of the non-circular lens 13 of the first lens group 10 and the first lens holder 61 are disposed in the space from the second lens group 20 to the reflection mirror 30. Both ends of the arch-shaped structure portion 61a protrude. For this reason, when the reflecting mirror 30 is replaced with a prism, it is necessary to employ a prism having a shape that avoids mechanical interference with these arched portions.

  In addition, the lens system 50 has a two-group configuration including a negative first lens group 10 and a positive second lens group 20, but a positive-negative two-group lens system and three or more groups. The configuration of the lens system according to the present invention can also be applied to a lens system having the above lens group. The configuration of the lens system according to the present invention can also be applied to a zoom lens system. Further, the configuration of the lens system according to the present invention is not limited to the rear projector 1 but can be applied to other image display devices such as a front projector with a separated screen. An imaging device such as a CCD can be disposed at the position of the light modulation device 7. Therefore, the lens system according to the present invention can be applied to an imaging apparatus including a camera, a telescope, a microscope, and the like.

The figure which shows schematic structure of a rear projector. Sectional drawing which shows schematic structure of a lens unit and a lens system. The top view which shows the external appearance of a lens unit. Sectional drawing which shows a mode that a lens unit is assembled. The expansion | deployment perspective view which shows a mode that a lens unit is assembled. The perspective view which shows the back surface of a 1st lens holder. The figure which lacks and shows a part of lens unit in order to show the state where the 1st lens holder was assembled to the 2nd lens holder. The figure which shows the virtual state which employ | adopted the circular lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rear projector 2 Screen, 4 Mirror, 5 Image generation apparatus 6 Illumination apparatus, 7 Light modulation device (DMD)
DESCRIPTION OF SYMBOLS 10 1st lens group, 11-13 Non-circular lens 11c-13c The cut part, 11a-13a Arch-shaped shape 20 2nd lens group, 30 Reflection mirror (optical element for angle conversion)
50 lens system 60 lens unit 61 first lens holder 62 second lens holder

Claims (8)

An optical element for changing the angle of the optical path between a first direction and a second direction;
A first lens group disposed adjacent to the first direction of the optical element, wherein at least one lens is arranged along a first optical axis;
A second lens group disposed in the second direction of the optical element, wherein at least one lens is arranged along a second optical axis;
The optical element is arranged such that the first optical axis and the second optical axis form an acute angle,
The first lens group includes a non-circular lens disposed adjacent to the optical element, and the non-circular lens has a concave part on the side of the optical element and a part cut on a circumference. whole including is D-shaped, wherein the cut portion is a portion where the side is cut in a concave arcuate shape including a position of said optical element, said arched shape, the first Combined to be perpendicular to the plane containing the optical axis and the second optical axis ,
When the optical path from the second lens group to the optical element is shifted in the direction of the cut portion with respect to the second optical axis, a part of the optical path is assumed to be a circular lens. Pass through the inside of the arched shape,
The lens system, wherein an optical path from the optical element to the first lens group is shifted to the opposite side of the cut portion with respect to the first optical axis .   The lens system according to claim 1, wherein the optical element is a reflection mirror. According to claim 1 or 2, wherein the first lens group has a negative refractive power, the second lens group has a positive refractive power, a lens system. A lens system according to any one of claims 1 to 3 ;
A first holder for holding the first lens group;
A second holder for holding at least the second lens group;
The first holder includes an arch-shaped structure having a concave on the side of the optical element, and the arch-shaped structure has the first optical axis and the second optical axis with respect to the second holder. A lens unit that is combined so as to be perpendicular to the plane that contains it. The lens unit according to claim 4 , wherein an inner side of the arch-shaped structure is a portion through which a part of the second holder passes. A lens system according to any one of claims 1 to 3 ;
Possess an optical modulation device for generating an image to be projected through the lens system,
The projector, wherein the light modulation device is disposed at a position optically shifted with respect to the second optical axis. The projector according to claim 6 , further comprising a mirror that reflects light output from the lens system toward a screen. A lens system according to any one of claims 1 to 3 ;
An image pickup apparatus having an image pickup device for picking up an image through the lens system.

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