WO2008029657A1

WO2008029657A1 - Image projecting device, and projection lens

Info

Publication number: WO2008029657A1
Application number: PCT/JP2007/066571
Authority: WO
Inventors: Hidetaka Hoshino; Yuji Hori; Katsuya Kawakita; Daisuke Nakayama
Original assignee: Brother Kogyo Kabushiki Kaisha
Priority date: 2006-09-04
Filing date: 2007-08-27
Publication date: 2008-03-13

Abstract

The projection lens to be used in the image projecting device is needed to project a projection image upward at a large projection field angle from a desktop. This necessity makes it necessary to enlarge the shape of the front lens positioned at the foremost stage. This necessity increases the weight of the front lens using a glass material and accordingly the weight of the image projecting device. This makes the image projecting device inconvenient for easy carriage. Provided is an image projecting device for projecting an image with a projection lens, which is equipped with a front lens made of a plastic material.

Description

Specification

Image projection apparatus and projection lens used therefor

Technical field

TECHNICAL FIELD [0001] The present invention relates to an image projection apparatus that displays an image or a still image displayed by an electro-optical element by enlarging and projecting the image on a screen, and in particular, among the plurality of lenses constituting the projection lens, the frontmost lens The present invention relates to an image projection apparatus that is made of plastic.

Background art

[0002] In recent years, image projectors incorporating electro-optical elements such as liquid crystal display elements and DMD (digital maicromirror device) display elements have become widespread! / This type of image projection device is easy to carry, and is installed on a desk or the like, and is used by projecting image light onto a projection screen obliquely upward that is higher than the height of the desk. Therefore, the optical axis of the projection lens for projecting the image does not match the center of the projection screen.

FIG. 16 is an external view of a conventionally known image projection apparatus 200 of this type. The image projector 200 includes a housing 201, an operation panel 203, a projection lens 202, a lens group 204 installed in the projection lens 202, and the like. The housing 201 houses an electro-optical element including a light source unit, a liquid crystal display element, a drive circuit for driving the electro-optical element, a power source, a projection lens 202, and the like. The image projector 200 is usually installed on a desk and projects image light in an obliquely upward direction.

FIG. 17 is a schematic cross-sectional view showing an example of a lens group constituting the projection lens 210. As shown in FIG. The first lens group 211 and the second lens group 212 are composed of a force, the first lens group 211 is a forcing lens, the second lens group 212 is a compensator lens, a relay lens, etc. . The first lens group 211 is held by the front barrel 214 by holding members 220 and 221. In particular, in the first lens group 211, the foremost lens 216 (hereinafter referred to as the front lens) is the largest and heaviest. The second lens group 212 is housed in the rear barrel 215 and held by holding members 222 and 223. Then, the image light from the liquid crystal display element 225 enters from below the optical axis 224 of the second lens group 212 and exits obliquely upward from above the optical axis 224 of the first lens group 211. Therefore, the first lens group 211 has an upper half of the optical axis. Only minutes are used.

[0005] In Patent Document 1, the camera barrel and the objective lens are integrally formed of transparent plastic, thereby reducing the number of assembly steps for assembling the optical member and the exterior member, and realizing an inexpensive camera. Are listed.

[0006] Patent Document 2 describes that a projection lens is cut in half and stored in a semi-cylindrical lens barrel having a base. When using the projection display device, the lens barrel is projected from the top of the projection display device casing, and when not in use, it is rotated so that the bottom of the lens barrel is at the top. It is described that it should not protrude from the upper surface of the body.

Patent Document 1: Japanese Patent Laid-Open No. 7-209714

Patent Document 2: Japanese Patent Laid-Open No. 2006-23361

Disclosure of the invention

Problems to be solved by the invention

[0007] This type of image projection apparatus has a large angle of view for projection. Therefore, it is necessary to make the diameter of the first lens group larger than that of the second lens group. In particular, in order to obtain a projection image with a large angle of view, the outer shape of the front lens located at the foremost stage of the projection lens must be enlarged, and when this is made of glass, a thick disc is used. It was necessary to polish the glass plate-like glass. As a result, processing of glass is difficult and expensive, and the material is glass, which increases the weight of the projection lens and makes the entire device heavier, which is a disadvantageous factor for easy carrying.

Means for solving the problem

In order to achieve the above object, according to one aspect of the present invention, in an image projection apparatus that projects an image using a projection lens, the projection lens is formed of a plastic material. A front lens is provided. According to the force and the configuration, the weight of the front lens can be reduced, so that it is possible to provide an image projection device that is easy to carry.

[0009] In order to achieve the above object, according to another aspect of the present invention, the projection lens includes a holding member that holds the front lens, and the front lens, the holding member, Were integrally formed of the plastic material. According to the configuration, it is possible to eliminate the process of attaching the front lens to the holding member, so that the assembly man-hour can be reduced, and the holding member is made of a plastic material, so the entire apparatus is reduced in weight. An image projection apparatus can be provided.

[0010] In order to achieve the above object, according to another aspect of the present invention, the holding member comprises:

A part of the lens barrel of the projection lens is configured. According to the configuration, since the process of mounting the holding member for holding the lens on the lens barrel can be omitted, the number of assembling steps can be reduced, and a part of the lens barrel is made of a plastic material. It is possible to provide an image projection apparatus that is lighter overall.

In order to achieve the above object, according to another aspect of the present invention, the projection lens includes a position adjustment member that adjusts a position of the front lens, and the position adjustment member and The front lens was integrally formed of the plastic material. According to such a configuration, it is possible to reduce the number of assembly and position adjustment processes between the position adjustment member and the front lens, and the position adjustment member is made of a plastic material, so that the entire apparatus can be reduced in weight. An apparatus can be provided.

[0012] In order to achieve the above object, according to another aspect of the present invention, the projection lens includes a fixing member for fixing the projection lens, the fixing member and the front lens lens. Is integrally formed of the plastic material. According to the configuration, it is possible to omit the step of fixing the front lens to the fixing member, and to provide an image projection apparatus that is light in weight because the fixing member is made of a plastic material. wear.

[0013] In order to achieve the above object, according to another aspect of the present invention, the front lens has a half-moon shape. According to the force and the configuration, the front lens can be reduced in weight, and an image projection apparatus that can be easily carried can be provided.

[0014] In order to achieve the above object, according to another aspect of the present invention, the front lens has a rectangular shape. According to this configuration, the image light formed by the liquid crystal display element or the like usually has a rectangular shape, so that the outer shape of the image light and the outer shape of the front lens can be matched, reducing the weight of the lens, Also, the amount of plastic material used Providing an image projection apparatus that can be reduced, easily carried, and reduced in weight can be achieved with the force S.

[0015] In order to achieve the above object, a thread groove is formed on the outer periphery. According to such a configuration, since the lens can be directly attached to the lens barrel, assembling becomes easy and the number of lens fixing members can be reduced. Therefore, an image projection apparatus that reduces the weight of the entire apparatus is provided. I can do it.

[0016] Further, in order to achieve the above object, according to another aspect of the present invention, the front lens has a position fixing groove or protrusion on an outer periphery. According to the force and the configuration, when the front lens is rotated and positioned, an image projection apparatus that can be reliably fixed at a specific position can be provided.

In order to achieve the above object, according to another aspect of the present invention, at least one lens constituting the projection lens is divided into a plurality of regions having different powers. According to this configuration, it is possible to provide an image projection apparatus that can project a plurality of different projection images without replacing the lens.

[0018] Further, in order to achieve the above object, according to another aspect of the present invention, the plurality of regions are regions divided into at least two parts around the vicinity of the optical axis. According to such a configuration, the force S can be provided to provide an image projection apparatus capable of projecting a plurality of different projection images around the vicinity of the optical axis.

[0019] In order to achieve the above object, according to another aspect of the present invention, the plurality of regions are located in the vicinity of the optical axis and divided into at least two by a plane substantially parallel to the optical axis. . According to this configuration, it is possible to provide an image projection apparatus capable of projecting two different projection images with a plane substantially parallel to the optical axis as a boundary.

[0020] Further, in order to achieve the above object, according to another aspect of the present invention, projection angles of view of images projected through the respective regions are made different from each other. According to the force and the structure, it is possible to provide an image projection apparatus capable of projecting projection images having different angles of view without exchanging lenses.

In order to achieve the above object, according to another aspect of the present invention, the at least one lens is the front lens. According to the power, the configuration, the power is different Since the front lens having the above-described region is used, it is possible to provide an image projection apparatus that can simplify the rotation mechanism for rotating the lens.

In order to achieve the above object, according to another aspect of the present invention, the at least one lens is a lens or a lens group adjacent to the front lens. According to such a configuration, since the lens adjacent to the front lens is also divided into a plurality of regions having different powers, it is possible to provide an image projection apparatus that expands the selection range of the projection field angle.

In order to achieve the above object, according to another aspect of the present invention, the projection lens includes an electro-optic element that converts light incident from a light source into image light, and the projection lens transmits the image light in advance. Is incident at a position shifted from the optical axis of the projection lens, and is enlarged and projected in a direction shifted from the optical axis, and at least one lens constituting the projection lens is connected to the optical axis. It is configured so that it can be placed at a position rotated around the center, and it is possible to use a plurality of areas having different powers. According to the above-described configuration, it is possible to provide an image projection apparatus that can use a plurality of regions having different powers selectively by rotating the lens around the optical axis.

In order to achieve the above object, according to another aspect of the present invention, the projection lens or at least one lens constituting the projection lens is configured to be rotatable by 180 °. According to this configuration, it is possible to provide an image projection apparatus that can easily switch between different projection images by rotating the lens by 180 °.

[0025] In order to achieve the above object, according to another aspect of the present invention, the image light does not cross a divided region that divides the at least one lens into a plurality of regions having different powers. I made it. According to this configuration, when the lens is rotated and switched for use, in any case, it is possible to provide an image projection apparatus that can project a projection image that does not cause partial chipping.

In order to achieve the above object, according to one aspect of the present invention, a projection lens used in the image projection apparatus is provided. According to the force and the configuration, it is possible to reduce the weight of the front lens, and therefore, when incorporated in an image projection apparatus, the entire apparatus can be reduced in weight and provided with an easy-to-carry image projection apparatus. it can.

The invention's effect According to the image projection apparatus of the present invention, a lens obtained by molding a plastic material is used as the front lens constituting the projection lens. As a result, it is lighter than a front lens made of a glass material cut and polished from a thick disk-shaped glass plate, and the weight of the image projector can be reduced, making it easy to carry around. It has the advantage of being able to obtain a simple image projection device.

[0028] When the projection image is enlarged and projected upward from the optical axis of the projection lens, the front lens of the projection lens uses, for example, only the upper half with respect to the optical axis. Therefore, it has the advantage that the front lens can be used with different power depending on the usage situation with different power, or the lower half can be cut to reduce the weight. Explanation

FIG. 1 is a schematic cross-sectional view of a projection lens used in an image projection apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a projection lens used in an image projection apparatus according to another embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of a projection lens used in an image projection apparatus according to another embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a front lens used in an image projection apparatus according to another embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view of a projection lens used in an image projection apparatus according to another embodiment of the present invention.

FIG. 6 is an external view of a front lens used in an image projection apparatus according to another embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a front lens portion of a projection lens used in an image projection apparatus according to another embodiment of the present invention.

FIG. 8 is an explanatory diagram of a front lens alignment mechanism used in an image projection apparatus according to another embodiment of the present invention.

FIG. 9 is a sectional view of a projection lens used in an image projection apparatus according to another embodiment of the present invention. FIG.

FIG. 10 is a schematic cross-sectional view of a projection lens used in an image projection apparatus according to another embodiment of the present invention.

FIG. 11 is a schematic cross-sectional view of a projection lens used in an image projection apparatus according to another embodiment of the present invention.

FIG. 12 is a schematic cross-sectional view of a lens used in an image projection apparatus according to another embodiment of the present invention.

FIG. 13 is a schematic cross-sectional view of a projection lens used in an image projection apparatus according to another embodiment of the present invention.

FIG. 14 is an overview of an image projection apparatus according to another embodiment of the present invention.

FIG. 15 is a diagram showing a state in which an image is projected by an image projection apparatus according to another embodiment of the present invention.

FIG. 16 is an external view of a conventionally known image projection apparatus.

FIG. 17 is a sectional view of a conventionally known projection lens.

Explanation of symbols

[0030] 1, 20, 30, 50, 90 Projection lens

2 First lens group

3 Second lens group

4 Outer lens barrel

5 Rear barrel

6 Front barrel

10, 21, 31, 41, 51, 71, 81, 91 Front lens

11, 15, 16, 17, 18, 22, 32 Holding member

33 Fixing member

12, 13 Glass lens

19 Optical axis

BEST MODE FOR CARRYING OUT THE INVENTION

[0031] In the image projector according to the embodiment of the present invention, the front of the projection lens As a ball lens, it is equipped with a plastic lens obtained by molding plastic material! Plastic materials can weigh less than half compared to lens glass. Therefore, there is an advantage that it is possible to reduce the weight of the entire image projection apparatus and to construct a device that is easy to carry.

[0032] As the plastic material, a transparent polycarbonate resin (hereinafter referred to as PC), a polymethylmethacrylate acrylic resin (hereinafter referred to as PMMA), or the like can be used. These plastic materials have a specific gravity of 1/2 or less compared to glass for lenses. The plastic material can be poured into a mold, or inserted into the mold and formed by press working. In order to use it as a lens, the inner surface of the mold used for these is given a high-precision mirror finish.

[0033] Further, the projection lens includes a holding member that holds the front lens, a lens barrel, a position adjustment member, or a fixing member for fixing the projection lens to the casing. These members are molded integrally with the front lens using the same plastic material. In order to prevent unnecessary reflected light, the surface of the member other than the front lens is coated with a black antireflection film. As a result, the number of parts can be reduced, the manufacturing process can be simplified, and the cost can be reduced. In addition, since the specific gravity of plastic materials is smaller than that of glass materials and metal materials, the overall weight of the apparatus can be reduced.

[0034] Further, the front lens may have a half-moon shape or a rectangular shape, and further, a thread groove for engaging with the lens barrel is formed on the outer periphery of the front lens, or Then, a rotational positioning groove or protrusion for the lens barrel is formed. When projecting an image with an elevation angle with respect to the optical axis of the projection lens of the image projector, the projected image light passes only through the upper half of the front lens, so the front lens is not necessarily circular. There is no need to be. Therefore, a frontal lens having a half-moon shape or a quadrangular shape only in a region through which image light passes can be obtained. When a lens is formed from glass, it is necessary to polish it from a circular glass plate. However, since the lens is formed by molding a plastic material, there is no such limitation. Similarly, a thread groove, a concave portion, and a convex portion can be formed on the outer periphery of the front lens. As a result, the entire projection lens can be formed to be lightweight and compact. [0035] At least one lens constituting the projection lens is divided into a plurality of regions having different powers. The one lens may be a front lens made of the plastic material! /, Or may be a lens or a lens group adjacent to the front lens. The plurality of divided areas are areas divided into at least two parts around the vicinity of the optical axis of the projection lens. For example, the region divided into two can be a region that is located in the vicinity of the optical axis of the projection lens and is divided into two by a plane substantially parallel to the optical axis. And it can comprise so that the projection view angle of the image light which passes through one divided | segmented area | region and the projection view angle of the image light which passes through another area | region may mutually differ.

[0036] In addition, the projection lens includes an electro-optical element that converts light incident from the light source into image light, and the projection lens is incident at a position shifted from the optical axis of the projection lens and shifted from the optical axis. Magnify and project in the direction. Furthermore, at least one lens constituting the projection lens can be used for a plurality of regions having different powers. For example, regions having different powers are formed in the upper half and the lower half with respect to the optical axis. By installing this lens so that it can rotate 180 °, the projection angle of view and the size of the projection image can be easily changed without changing the projection lens. In this case, image light is prevented from passing through the divided areas divided into the plurality of areas. This makes it possible to project an image without being partially missing!

Hereinafter, the present embodiment will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a projection lens 1 used in an image projection apparatus according to an embodiment of the present invention. The projection lens 1 includes a first lens group 2 that arranges image light on the emission side and a second lens group 3 that arranges image light on the incident side. The first lens group 2 is a focusing lens, and the second lens group is a relay lens or a compensator lens group. The first stage of the first lens group 2 is a front lens 10, which is made of a transparent plastic material. The front lens 10 is fixed to the inner periphery of the front barrel 6. The front lens 10 is integrally formed with a holding member 11 for holding the rear glass lens 12. The rear glass lens 13 and the composite glass lens 14 are held by holding members 15 and 16 that are separate from the plastic of the front lens 10 and the holding member 11. The second lens group 3 is composed of a plurality of glass lenses, and is fixed and held on the rear barrel 5 by holding members 17 and 18. Front barrel 6 and The rear barrel 5 is held by the outer barrel 4 so as to be able to advance and retract. The projection lens 1 has a symmetric structure around the optical axis 19.

[0039] The front lens 10 is made of ABS (acrylonitrile) in addition to transparent PC and PMMA resin.

Plastic materials such as' Butadiene.Styrene) can be used. These plastic materials can be formed by injection molding or press molding using a mold. In this case, the inner surface of the mold corresponding to the area of the front lens 10 is subjected to high-precision mirror polishing.

[0040] This makes it possible to reduce the weight of the front lens by half or less compared to when the lens is formed of glass. Further, since the holding member for the rear glass lens 12 is integrally formed, the number of parts can be reduced.

FIG. 2 is a schematic cross-sectional view of a projection lens 20 according to another embodiment. The same reference numerals are given to the same parts or parts representing the same function. A different part from FIG. 1 is that a front lens 21 by plastic molding is formed by integrally molding a holding member 22 for holding a glass lens 12 and a front barrel 23. In the front barrel 23, a glass lens 13 and a holding member 15 for holding the glass lens 13 and a composite glass lens 14 and a holding member 15 for holding the glass lens 13 are accommodated therein. Thus, by forming the front lens barrel 23 and the front lens 21 integrally, the number of parts and the assembly process can be reduced.

FIG. 3 is a schematic cross-sectional view of a projection lens 30 according to another embodiment. The same reference numerals are assigned to the same parts or parts representing the same function. 2 differs from the projection lens shown in FIG. 2 in that the front lens 31, the holding member 32 that holds the glass lens 12, and the front lens barrel 23, and the fixing member 33 that fixes the projection lens 30 are made of plastic material. This is a one-piece molding. The glass lens 13 and the composite glass lens 14 are fixed to the front barrel 23 by holding members 15 and 16. The second lens group 3 is fixed to the rear barrel 5 by holding members 17 and 18. The front lens barrel 23 and the rear lens barrel 5 are slidably fixed to the outer lens barrel 4. The entire projection lens 30 is fixed to the front panel 34 by a fixing member 33 and a screw 35. The front lens 31 is transparent, and a light shielding film (not shown) is attached to the inner walls of the other holding members 32 and the front lens barrel 23 to prevent unnecessary light from being transmitted or reflected. In the above embodiment, the fixing member 33 formed integrally with the front lens 31 is not attached to the front lens 31. The front panel 34 and the front lens 31 may be integrally molded. As a result, the number of parts and the assembly process can be reduced, and the weight of the entire apparatus can be reduced.

FIG. 4 is a schematic cross-sectional view showing a front lens according to another embodiment. FIG. 4 (a) shows a state before the front lens 41 is inserted into the front barrel 43. FIG. Figure 4 (b) shows the state after insertion. The front lens 41 made of a plastic material has an arrowhead-shaped notch portion 42 on a part of its outer periphery. The front lens 41 and the notch 42 are formed by integrally molding a plastic material. A V-groove 44 is formed on the inner surface of the front barrel 43. As shown in FIG. 4 (b), when the front lens 41 is inserted into the front lens barrel 43, the notch 42 is engaged with the V-groove 44, and the front lens 41 is inserted into the front lens barrel 43. Fixed. This reduces the process of assembling the projection lens.

FIG. 5 is a schematic cross-sectional view of a projection lens 50 used in an image projection apparatus according to another embodiment of the present invention. The same parts or parts having the same functions are denoted by the same reference numerals. In FIG. 5, the front lens 51 and the front lens barrel 52 are formed by integral molding of a plastic material. The glass lenses 12 and 13 and the composite glass lens 14 of the first lens group 2 are fixed to the front barrel 52 by holding members 15 and 16. In the second lens group 3, a lens made of glass is fixed to the rear barrel 5 by holding members 17 and 18. The front lens barrel 52 and the rear lens barrel 5 are slidably held by the outer lens barrel 4. Further, a plate-like movable portion 53 is formed below the front lens 51. The movable portion 53 is integrally formed of a plastic material together with the front lens 51 and the front barrel 52. A rack 54 is formed on the lower surface of the plate-like movable portion 53 and mates with a pinion 55 attached to the rotating shaft 61. The rotary shaft 61 is rotatably attached to the lower part of the outer barrel 4 or the casing. The rotating shaft 61 further includes a worm wheel 56 and meshes with a worm 57 formed on a part of the rotating member 58. The rotating member 58 can be rotated from the outside by a knob (not shown). A spring 59 is attached to the side of the movable part 53 opposite to the front lens 51. The other end of the spring 59 is attached to a lower portion of the outer lens barrel 4 or a fixed portion 60 fixed to the casing, and applies stress to the front lens 51 and the front lens barrel backward.

[0045] By rotating the rotating member 58, a rotational force is applied from the worm 57 to the worm wheel 56. And the rack 54 moves back and forth as the pinion 55 rotates. Thus, the first lens group 2 can move back and forth with respect to the second lens group 3, and the focus of the projected image can be adjusted.

FIG. 6 is an external view showing the shape of a front lens used in an image projection apparatus according to another embodiment. In the projection lens for enlargement projection of the image projection apparatus, the image light passes through the upper half region of the first lens group 2 with respect to the optical axis 19. If an image is projected with an elevation angle around the optical axis 19, the projected image will be distorted, so this distortion is prevented. Therefore, in the front lens, the lower half from the center of the lens is not used.

FIG. 6 (al) is a front view of a front lens made of semicircular plastic, and FIG. 6 (a2) is a cross-sectional view of the portion XX ′. The lens is formed in the upper half from the optical axis 19 of the projection lens, and the lower half is cut. This makes it possible to reduce the weight of the lens and reduce the amount of plastic material used to make up the lens. Fig. 6 (bl) is a front view of a front lens made of a square plastic lens, and Fig. 6 (b2) is a cross-sectional view of the Y-Y 'portion. A rectangular lens is formed in the upper half from the optical axis 19 of the projection lens, and the lower half is cut. In the image projection apparatus, an image displayed on the liquid crystal display element and an image reflected from the DMD usually have a square shape. Thus, the projection lens need not be circular. Therefore, the front lens is formed in a quadrangular shape, and the lens is configured in the region through which the image light passes. This reduces the weight of the lens and reduces the amount of plastic material used. In addition to a half-moon shape or a quadrangular shape, a hexagonal shape or a polygonal shape can be used. These front lens were formed by plastic molding, pressing, etc. For this purpose, unlike a glass lens, it is possible to design a lens having an asymmetric shape relatively freely.

FIG. 7 is a cross-sectional view showing a front lens part of a projection lens according to another embodiment.

7 (a) shows the state before the front lens 71 is inserted into the front barrel 73, and FIG. 7 (b) shows the state where the front lens 71 is inserted into the front barrel 73. . A male screw groove 72 is formed on the outer periphery of the front lens 71, and a female screw groove 74 is formed on the inner periphery of the front lens barrel 73. The front lens 71 is screwed into the front lens barrel 73. Combine and fix. As a result, the front lens 71 is It is possible to reduce the size and size of the projection lens without the need to use a holding member when installing on the cylinder 73.

FIG. 8 is an explanatory diagram for explaining a front lens positioning mechanism regarding a projection lens according to another embodiment. FIG. 8 (al) is a front view showing a state in which the front lens 81 is fixed to the front barrel 83, and FIG. 8 (a2) is a side sectional view thereof. A male screw groove is formed on the outer periphery of the front lens 81, and a female screw groove is formed on the inner periphery of the front lens barrel 83, and the front lens 81 is screwed into and fixed to the front lens tube 83. ing. Further, a recess 82 formed of a groove is formed on a part of the outer periphery of the front lens 81. The front lens barrel 83 is provided with a stopper 84. The front end of the stopper 84 passes through a through-hole 87 provided in the front lens barrel 83, and the rear end is fixed to an outer lens barrel or a casing (not shown). The stopper fixing part 85 is inserted into the opening and fixed so that it can be moved forward and backward. The stopper 84 is pressed against and contacts the front lens 81 by a spring 86 provided between the stopper fixing portion 85 and the stopper 84. In FIG. 8 (al), the tip end portion of the stopper 84 is inserted into the concave portion of the front lens 81 and the rotation angle of the front lens 81 is fixed.

FIG. 8 (bl) is a front view of the front lens barrel 83 when the front lens 81 is rotated to the right by about 45 °, and FIG. 8 (b2) is a side sectional view thereof. By rotating the front lens 81, the stopper 84 is pushed upward. Then, after one rotation, the concave part 82 of the front lens 81 reaches the upper part and is fixed by the stopper 84. Thus, by providing the concave portion 82 in the front lens 81, the front lens 81 can be reliably fixed at a specific rotation angle in the case of a lens having an asymmetric shape with respect to the optical axis. The front lens 81 may be a rectangular lens or a circular lens in addition to the semicircular lens of the asymmetric lens. In the above embodiment, a concave portion is formed on the front lens, a convex portion is formed instead of the concave portion, and the convex portion is engaged with the front barrel or the outer barrel at a specific rotation angle. It may be fixed.

FIG. 9 shows a projection lens 90 according to another embodiment, FIG. 9 (a) is a sectional view of the projection lens 90, and FIG. 9 (b) is an external view thereof. The same parts and parts having the same functions are denoted by the same reference numerals. In FIG. 9B, the outer barrel 94, the front barrel 92, and the rear barrel 93 have a cylindrical shape with a flat bottom portion 95. In Fig. 9 (a), the front lens 91 is an asymmetric lens with a flat bottom, and is molded integrally with the front barrel 92 from a plastic material. It is. Similarly, the holding members 15, 16, 17, and 18 that hold the lenses have asymmetric shapes at the upper and lower portions. That is, the optical axis 19 of the projection lens 90 is located below the center of the lens barrel. The image light incident from the rear part passes below the optical axis 19 in the second lens group 3 and passes above the optical axis 19 in the first lens group 2.

[0052] By forming the projection lens 90 in this way, the volume of the front lens 91 can be reduced and the weight can be reduced, and at the same time, the outer lens barrel 94, the front lens barrel 92, and the rear lens barrel 93 can be reduced. Reduction in size and weight can be achieved.

FIG. 10 is a schematic cross-sectional view showing a projection lens 100 according to another embodiment. The same parts or parts having the same functions are denoted by the same reference numerals. The internal structure of the outer lens barrel 94 of the projection lens 100 is the same as that of the projection lens 90 shown in FIG. That is, the projection lens 100 has an asymmetric structure with the optical axis 19 as the center, and the front lens 101 constitutes only the upper half lens. In the lower part of the projection lens 100, a movable part 53 is formed below the front lens 101, as shown in FIG. The movable portion 53 is integrally formed with the front lens 101 and the front barrel 92. A rack 54 is formed on the lower surface of the movable portion 53 and engages with a pinion 55 attached to the rotating shaft 61. As described below with reference to FIG. 5, the focus of the projection lens 100 can be adjusted by rotating the rotary member 58. The normal focus is a force that is adjusted by rotating the front lens 91 or the like. When the front lens 101 has an asymmetric structure with respect to the optical axis 19 as in this embodiment, the front lens 101 cannot rotate. Therefore, such a configuration using the rack 54 and the pinion 55 is particularly effective.

Next, with reference to FIGS. 11 to 15, regarding the projection lens used in the image projection apparatus according to the present invention, in particular, at least one lens constituting the projection lens is divided into a plurality of regions having different powers. An embodiment is described.

[0055] This type of image projection apparatus carries an image projection apparatus and a projection screen, and appropriately installs it in a room to project an image. At that time, the size of the room, the installation of the projection screen, the distance to the image projector, etc. are limited. When the projection angle of view of the image projection device is fixed, in a room environment where the distance between the projection screen and the image projection device is far, the projection image becomes too large and only a part of the image is displayed on the projection screen. Displayed, causing the inconvenience of not being able to see the whole. In addition, the space between the image projector and the projection screen is narrow. If it is too large, there is a disadvantage that the projected image becomes too small.

[0056] Some projection lenses have a zoom mechanism and can change the projection angle of view. This type of projection lens requires a focusing lens and a compensator lens, as well as a nourita lens, and because it uses a large number of lenses, the volume is large and the weight is heavy. It becomes disadvantageous as a device to set in. In addition, when changing the projection angle of view, a complex and precise movable mechanism was required to move these lens groups relative to each other.

Therefore, at least one lens constituting the projection lens is divided into a plurality of areas having different powers. Thus, the force S can be obtained to obtain a plurality of different types of projection images without changing the lens.

FIG. 11 (a) is a schematic cross-sectional view showing the configuration of the wide-angle projection lens 110 that performs wide-angle projection, and FIG. 11 (b) shows the configuration of the narrow-angle projection lens 116 that performs narrow-angle projection. FIG. 11C is a schematic cross-sectional view showing a configuration of a multi-angle projection lens 117 including a lens having a plurality of regions having different powers. Parts having the same function or functions are given the same reference numerals.

In FIG. 11 (a), the wide-angle projection lens 110 includes a first lens group 2 and a second lens group 3. The first lens group 2 constitutes a focus lens group. The second lens group includes a compensator lens that corrects the defocus and a relay lens for image formation. The image light emitted from the liquid crystal display element 112 passes through a region below the optical axis 19 and passes above the optical axis of the first lens group 2 to move upward at an angle of projection angle Θa. Is projected to enlarge. A front lens lens Wa is provided on the forefront of the first lens group 2. The front lens Wa is a concave lens and has negative power.

In FIG. 11 (b), the different part from FIG. 11 (a) is the front three lenses of the first lens group 2, and the other parts are the same. The front lens Na is a convex lens and has positive power. The front lens Na has a relatively positive power compared to the lens "&" in Fig. 11 (&). The lens Nc has a relatively positive power compared to the lens Wc in Fig. 11 (a). The projection angle of view Θ b of the narrow angle projection lens 116 is smaller than the projection angle of view Θ a of the wide angle projection lens 110.

FIG. 11 (c) shows an embodiment of the present invention. The front lens 118 of the first lens group 2, the middle lens The lens 119 and the rear lens 115 are the same as the three front lenses of the narrow angle projection lens 116 in the upper half of the optical axis 19 and the three front lenses of the wide angle projection lens 110 in the lower half of the optical axis 19 Is the same. More specifically, the first three lenses of the first lens group 2 are divided into a plurality of regions having different powers. The front lens 118 which is a front lens includes a region N ′ a where the upper part of the optical axis 19 has positive power and a region W ′ a which has a negative power below the optical axis 19. The next middle lens 119 includes a region N ′ b above the optical axis 19 and a region W ′ b below the optical axis, and the power of the upper region N ′ b is relatively lower than the lower W. 'Less than the power of b. The next rear lens 115 includes a region N ′ c above the optical axis 19 and a region W ′ c below the optical axis 19, and the power of the upper region N ′ c is relatively lower. Greater than W'c power. The upper and lower divisions are located in the vicinity of the optical axis 19 and are divided by a plane substantially flat with the optical axis 19.

As a result, the image light incident from below the optical axis 19 of the second lens group 3 is projected at a narrow angle by the projection field angle Θa. On the other hand, if the liquid crystal display element 112 ′ is arranged above the optical axis 19, it is projected below the optical axis 19 with a larger projection angle of the projection angle of view Θa. Similarly, if the liquid crystal display element 112 is fixed and the multi-angle projection lens 117 is rotated 180 ° around the optical axis 19, the projection field angle Θ b can be easily switched from the projection field angle Θ a. . In this case, the image light that has passed through the liquid crystal display element 112 is prevented from crossing the divided region that is divided vertically. Thus, the force S prevents the projected image light from being unnaturally divided.

[0063] In the above description, the force V, the shifting force, and the single lens can be divided into a plurality of regions in which the three lenses in front of the first lens group 2 are divided into a plurality of regions having different powers. . For example, only the front lens 118 that is the front lens can be divided into a plurality of regions and used. Further, in the above description, the force described in the example in which one lens is divided into two is not limited to this, and one lens can be divided into three or more.

[0064] In addition to the case where one color liquid crystal display element is used as the liquid crystal display element 112, for three liquid crystal display elements that display each color of R (red), G (green), and B (blue). The power S can be used. For example, the light from the light source is divided into three by a dichroic mirror, and each of the divided light fluxes is passed through an RGB color filter to display three liquids that display R, G, and B colors. It is also possible to irradiate a color light beam corresponding to the crystal display element, combine the image light of each color emitted from each liquid crystal display element, and enter the projection lens. In this case, a full color image is formed by additive color mixing. In addition, a reflective liquid crystal display element can be used instead of the transmissive liquid crystal display element.

In addition, a DMD display element can be used instead of the liquid crystal display element. The DMD display element has a two-dimensional arrangement of fine mirrors on a semiconductor substrate, and changes the angle of each mirror according to the image signal. When the light incident on the DMD is reflected, the reflected light reflects the image. Form. In the image projection device, the light beam from the light source is time-divided into RGB colors through a rotating color filter and irradiated to the DMD. In the DMD, the time-divided RGB light is incident, a mirror on the semiconductor substrate is rotated in synchronization with the RGB light, and the reflected light reflected by the mirror forms image light. The image light enters the projection lens and is projected onto the projection screen. In this case, a full color image is formed by time mixing.

FIG. 12 (a) is a schematic cross-sectional view of a lens used in the present embodiment, and FIG. 12 (is a schematic plan view. Centering on the optical axis 19 of the multi-angle projection lens 7. The upper half has the region N'x and the lower half has the region W'x, where the upper half lens has positive power and the lower half has negative power. When used as a lens, the upper half with positive power has a smaller projection angle of view than the lower half, and the upper half has a smaller radius than the lower half. However, it is possible to make the upper and lower surfaces have the same radius as long as it is possible to manufacture the lenses without different lens radii, such as a normal glass lens having an upper half lens power and a lower half lens power. Create a normal glass lens with lens power individually, and then change its optical axis. Cut and cut across each other and bond each cut so that their optical axes coincide, or create a mold with the shape shown in Fig. 12 and make a transparent plastic material such as transparent Force-A lens material made of sulfonate resin (PC), polymethyl 'metatalylate' acrylic resin (PMMA), etc. can be cast into the mold or formed integrally by pressing the mold. In this case, it can be configured to be fixed to a lens barrel holding the lens in a separated state without being bonded to each other. FIG. 13 is a schematic cross-sectional view of a projection lens 130 in which a multi-angle projection lens 117 incorporating the lens formed as described above is incorporated in a lens barrel. The same reference numerals are given to the same parts or the same functions.

A fixed barrel 131 and a movable barrel 133 are inserted into the outer barrel 132. Some lenses of the second lens group 3 and the first lens group 2 are fixed to the fixed cylinder 131 by the holding unit 135. A front lens 118, a middle lens 119, and a rear lens 115 of the first lens group 2 are fixed to the movable tube 133. These lenses have two regions with different powers about the optical axis 19. A rotating knob 134 is provided outside the movable cylinder 133. The movable cylinder 133 is rotatably fixed to the outer barrel 132. The liquid crystal display element 112 is disposed below the optical axis 19 and the projection lens is irradiated with image light from below the optical axis 19. In the area of the first lens group 2, the incident image light passes through the upper lens area from the optical axis 19 and is projected from the upper area from the optical axis 19 of the front lens 118. When the movable cylinder 133 is rotated 180 ° by the rotary knob 134, the front lens 118, the middle lens 119, and the rear lens 115 are turned upside down and the projected angle of view is changed. Between the outer barrel 132 and the movable barrel 133, there is a mechanism in which a stopper works every 180 ° rotation by a stopper (not shown).

[0069] In the above embodiment, the movable cylinder 133 is rotatably inserted into the outer barrel 132. However, the movable cylinder 133 is not necessarily configured to be rotatable, and the movable cylinder 133 is temporarily removed and rotated 180 °. You may make it buy after.

[0070] In the above example, the three lenses have a plurality of regions having different powers, and the force that rotates the three lenses is used. A movable lens having a plurality of different regions may be used. In addition, the structure can be simplified by rotating only the front lens of the front lens 118 with a plurality of regions. Further, all the lenses of the first lens group 2 and the second lens group 3 may be fixed to the movable cylinder, and the entire lens may be rotated with respect to the fixed cylinder. Further, the force S can be obtained by electrically rotating the movable cylinder 133 by a stepping motor or the like. This is convenient when operating the image projector from a distance.

FIG. 14 is an overview diagram showing an image projector 140 incorporating the projection lens 130 shown in FIG. 13 and a PC terminal 145 that transmits image data to the image projector 140. Image throw The shadow device 140 includes a light source, a liquid crystal display element, a driver for driving the liquid crystal display element, an input port for receiving image data, a projection lens, and the like. The image projection apparatus houses each of these elements in a housing 141. An operation panel 142 is provided on the upper surface of the housing 141, and a projection lens 130 is provided on a side surface of the housing 141. The movable tube 133 of the projection lens 130 is provided with a rotary knob 134 on the outer periphery thereof, and can be manually rotated.

FIG. 15 shows a state in which an image is projected by the image projection device 140 shown in FIG. 14. FIG. 15 (a) shows a case where the projection angle of view is small! / ヽ, and FIG. 15 (b) shows a projection. The angle of view is large! /, Respectively. In FIG. 15 (a), a state in which an image from the liquid crystal display element is projected by rotating the rotary knob 134 provided on the movable tube 133 of the projection lens 130 upward is shown. The image light emitted from the liquid crystal display element passes through the upper half area of the first lens group 2 and is projected with a projection angle of view Θb. In this case, it is appropriate when the distance X between the screen 150 and the image projector 140 is large. Fig. 15 (b) shows the projection state when the rotary knob 134 is rotated 180 ° and fixed downward. The image light emitted from the liquid crystal display element is projected at a large angle of projection angle of view Θa. This is appropriate when the distance X between the screen 150 and the image projection device 140 is small.

As described above, the image projection apparatus according to the present embodiment has the convenience that the projection angle of view can be changed with a very simple operation according to the environment in which the image is projected.

Industrial applicability

[0074] At least the front lens constituting the projection lens is formed of a plastic material, and the entire apparatus is reduced in weight, so that the portable image projection apparatus is obtained.

Claims

The scope of the claims

[I] An image projection apparatus for projecting an image using a projection lens, wherein the projection lens is formed of a plastic material and includes a front lens. Projection device.

[2] The projection lens may include a holding member that holds the front lens, and the front lens and the holding member may be integrally formed of the plastic material. The image projection apparatus described.

3. The image projector according to claim 2, wherein the holding member constitutes a part of a lens barrel of the projection lens.

[4] The projection lens includes a position adjusting member that adjusts a position of the front lens, and the position adjusting member and the front lens are integrally formed of the plastic material.

The image projection apparatus according to claim 1, wherein V is an image projection apparatus.

[5] The projection lens includes a fixing member for fixing the projection lens, and the fixing member and the front lens are integrally formed of the plastic material. The image projection apparatus described in 1.

6. The image projection device according to claim 1, wherein the front lens has a half-moon shape.

7. The image projecting device according to claim 1, wherein the front lens has a rectangular shape.

8. The image projection apparatus according to claim 1, wherein the front lens has a thread groove formed on an outer periphery thereof! /.

9. The image projection device according to claim 1, wherein the front lens has a position fixing groove or protrusion on an outer periphery.

10. The image projection device according to claim 1, wherein at least one of the lenses constituting the projection lens is divided into a plurality of regions having different powers! /.

[I I] The image projection device according to claim 10, wherein the plurality of regions are regions divided into at least two parts around the vicinity of the optical axis.

[12] The plurality of regions are located in the vicinity of the optical axis and are reduced by a plane substantially parallel to the optical axis. 12. The image projection apparatus according to claim 11, wherein the image projection apparatus is divided into at least two parts.

13. The image projection device according to claim 10, wherein projection angles of view of images projected through the respective regions are different from each other.

14. The image projection device according to claim 10, wherein the at least one lens is the front lens.

15. The image projection device according to claim 14, wherein the at least one lens is a lens or a lens group adjacent to the front lens.

[16] including an electro-optic element that converts light incident from the light source into image light,

The projection lens is incident on the image light at a position shifted from the optical axis of the projection lens, and enlarged and projected in a direction shifted from the optical axis.

The at least one lens constituting the projection lens is configured to be arranged at a position rotated about the optical axis so that a plurality of regions having different powers can be used properly. Item 10. The image projection device according to Item 10.

17. The image projection device according to claim 16, wherein the projection lens or at least one lens constituting the projection lens is configured to be rotatable by 180 °.

18. The image projection apparatus according to claim 16, wherein the image light does not cross a divided area that divides the at least one lens into a plurality of areas having different powers.

[19] A projection lens used in the image projection apparatus according to [1].