JP2014048502A - Image projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce working cost by reducing the number of precision requirements of cam groove working in a projection lens unit.SOLUTION: In an image projection device 100 including a light source 21, a projection optical system 10 forming an image with a luminous flux from the light source 21 on a screen 50, a lens barrel 11 holding the projection optical system 10, and a main body structure 60 integrally holding those members, the optical axis of the light source 21 is nearly in parallel with the installation surface of the main body structure 60, the screen 50 and the optical axis of the projection optical system 10 are arranged nearly in parallel with the normal line of the installation surface, and the lens barrel 11 includes a cam frame 13 in which a cam groove 12 enabling movement in an optical axis direction is formed, and a cylindrical optical axis positioning part 14 coming into contact with the gam groove 12 and radially formed around the optical axis. The optical axis positioning part 14 comes into contact with the groove end surface 12a on the side nearer to the installation surface, in the groove formed in the cam frame 13, to be positioned.

Description

  The present invention relates to an image projection apparatus.

  Liquid crystal projectors that are widely known as image projection apparatuses have recently been improved in the resolution, the price, and the like due to the higher resolution of the liquid crystal panel, the higher efficiency of the light source lamp. In addition, a small and light image projection apparatus using DMD (DigitAl Micro-mirror Device) or the like is widespread, and the image projection apparatus is being widely used not only in offices and schools but also at home. In particular, front type projectors have improved portability and are used for small conferences of several people.

  In addition, the conventional image projection apparatus requires a projection distance of several meters between the screen and the projection surface such as a wall, which is a display medium, but a large screen display can be obtained with a very short projection distance. A so-called ultrashort focus type image projection apparatus has been developed. This ultra-short focus type image projection apparatus has an advantage that the shadow of the presenter does not appear in the presentation.

  In such an image projection apparatus, generally, diverging light from a light source is adjusted by each optical element, and is condensed toward a projection surface (screen) by a projection optical system such as a projection lens to form an image. ing.

  In addition, a configuration in which a part of the projection optical system is moved in the optical axis direction to change the projection size (zoom) and adjust the focus position (focus) is a common configuration. The zoom and focus effects can be obtained by moving the plurality of lenses and the lens group back and forth in the optical axis direction.

  For example, there are a lens barrel that holds a lens and a lens group that form a projection optical system, a cam frame is arranged so as to surround the outer periphery of the lens barrel body, and an optical axis positioning portion provided on each lens moving ring is camped By engaging with a cam groove formed in the frame and rotating the cam frame, each lens moving ring is driven in the optical axis direction to perform zooming and the like.

  As such a technique, for example, in Patent Document 1, a lens that is supported by two guide bars that are guided in the optical axis direction within the barrel main body and that is movable in the optical axis direction that holds a plurality of lens groups. And a cam member configured to control the lens moving ring at a predetermined position. The cam unit includes a cam member that rotates about the optical axis and a cam follower provided in the lens moving ring. Is a lens barrel that drives the lens moving ring in the direction of the optical axis by rotating the lens about the optical axis, and the cam member is disposed on the outer periphery of the barrel main body, and the cross-sectional shape perpendicular to the optical axis is an arc shape A lens barrel that is formed in such a manner that the angle of an arc centered on the optical axis is 180 degrees or less is disclosed.

  In Patent Document 2, in a lens barrel including a cam barrel provided with a plurality of cams for moving at least a part of the photographing optical system in the optical axis direction, the cam barrel is provided on the outer periphery. The outer periphery cam, the inner periphery cam provided on the inner periphery, and the outer periphery cam and the inner periphery cam are not allowed to penetrate each other at a position where they are arranged so as to overlap or be close to each other in the radial direction of the cam cylinder. A lens barrel having an intermediate separating portion provided on the lens is disclosed.

  By the way, unlike an imaging optical system such as a camera that obtains a certain amount of light depending on natural light or the environment, the projection optical system generates a large amount of heat from the light source and prevents lens position shift due to deformation of the lens barrel caused by heat. Therefore, a projection lens unit is often formed by a lens barrel made of a metal member. Hereinafter, the projection lens unit is a generic name for the projection optical system and the lens barrel.

  When performing zoom or focus adjustment in the projection optical system, as described above, a cam frame having a cam groove formed as a guide for moving the lens barrel in the optical axis direction is required. When it is made of a metal member, it requires cutting with high precision when forming the cam groove, and also requires accuracy in combination with the lens barrel body that is generated during assembly. There is a problem that it becomes an increase factor. In addition, since high machining accuracy is required, a machining error occurs and a return to the design occurs, which can be a cause of an increase in lead time. However, the above-mentioned Patent Documents 1 and 2 do not disclose solving the problem about the reduction of the processing cost.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image projection apparatus that can reduce the number of cam groove machining precision required in a projection lens unit and reduce the machining cost.

  In order to achieve this object, an image projection apparatus according to the present invention holds a projection optical system including a light source, a plurality of lenses that form a light beam emitted from the light source on a projection surface in a desired image, and the projection optical system. In the image projection apparatus having the lens barrel that performs and a main body structure that integrally holds them, an optical axis of the light source is substantially parallel to an installation surface of the main body structure, and the projection surface And the optical axis of the projection optical system is arranged substantially parallel to the normal of the installation surface of the main body structure, and the lens barrel is rotated to the outermost part by itself. A cam frame formed with a groove that allows the lens barrel to move in the optical axis direction; a cylindrical optical axis positioning portion that is in contact with the groove of the cam frame and is formed radially about the optical axis; The optical axis positioning portion is a groove formed in the cam frame. Chi, by abutting on the groove end face on the side close to the installation surface of the body structure, is intended to position the cam frame.

  According to the present invention, it is possible to reduce the number of precision required parts for cam groove processing in the projection lens unit and to reduce the processing cost.

It is a schematic diagram which shows an example of the basic composition of an image projector. It is a side view which shows schematic structure of the image projection apparatus which concerns on this embodiment. It is a perspective view which shows schematic structure of the image projection apparatus which concerns on this embodiment. It is a side view of a projection lens unit. It is a perspective view of a projection lens unit.

  Hereinafter, the configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

[First Embodiment]
An image projection apparatus (image projection apparatus 100) according to this embodiment includes a light source (light source 21) and a projection optical system including a plurality of lenses that form a light beam emitted from the light source on a projection surface (screen 50) in a desired image. In an image projection apparatus having (projection optical system 10), a lens barrel (lens barrel 11) that holds the projection optical system, and a main body structure (main body structure 60) that holds them integrally. The optical axis of the light source is approximately parallel to the installation surface of the main body structure, and the projection surface and the optical axis of the projection optical system are approximately parallel to the normal of the installation surface of the main body structure. The lens barrel has a cam frame (cam frame 13) formed with a groove (cam groove 12) that allows the lens barrel to move in the direction of the optical axis by rotating itself. In contact with the groove of the cam frame and formed radially around the optical axis A cylindrical optical axis positioning part (optical axis positioning part 14), and the optical axis positioning part is a groove end face (end face) closer to the installation surface of the main body structure among grooves formed in the cam frame. 12a), and is positioned on the cam frame. In addition, the code | symbol in embodiment and the example of application are shown in a parenthesis.

  First, an example of the basic configuration of the image projection apparatus will be described with reference to FIG. FIG. 1 is a schematic diagram showing a basic configuration of the image projection apparatus 100. The image projection apparatus 100 includes a projection optical system 10, an illumination optical system 20, a separating unit 30, and an image forming element 40. Further, the image projection apparatus 100 may include an illumination power source (not shown), a modulation unit of the image forming element 40, an image processing unit, and the like.

  The illumination optical system 20 includes a light source 21. For example, the illumination optical system 20 is reflected by the reflector 22 (may be integrated with the light source 21), the relay lenses 23 and 24, and the reflector 22, and has directivity. The illuminance uniformizing means 25 or the like called an integrator optical system for uniformizing the illuminance of the luminous flux is provided so that a uniform illumination distribution can be obtained on the surface of the image forming element 40. As the light source 21, a halogen lamp, a xenon lamp, a metal halide lamp, an ultrahigh pressure mercury lamp, an LED, or the like is used.

  In addition, the color light may be projected by using the color wheel 26 to color the illumination light and controlling the image of the image forming element 40 in synchronization therewith.

  When a reflection type liquid crystal image forming element is used as the image forming element 40, more efficient illumination is possible by using the separating means 30 that separates the illumination light path and the projection light path. When a micromirror device type (DMD) is used as the image forming element 40, optical path separation using a total reflection prism or the like is employed. As described above, an appropriate optical system may be employed according to the type of the image forming element 40.

  In addition, by using a plurality of image forming elements 40 such as red, green, and blue, illuminating light that has passed through the color filters is applied, and light synthesized by the color synthesizing unit is incident on the projection optical system 10. A color image can be projected on the screen 50.

  In the image projection apparatus 100, the image forming element 40 forms an image according to the modulation signal. Illumination light from the light source 21 is applied to the image forming element 40, and the image formed on the image forming element 40 is enlarged and projected onto the screen 50 by the projection optical system 10.

  Next, the image projection apparatus 100 according to the present embodiment will be described with reference to FIGS. 2 is a side view showing a schematic configuration of the image projection apparatus 100, FIG. 3 is a perspective view showing a schematic configuration of the image projection apparatus 100, FIG. 4 is a side view of the projection lens unit 15, and FIG. 5 is a projection lens unit. FIG.

  The image projection apparatus 100 projects a light beam emitted from a light source 21 through a projection optical system 10 held in a lens barrel 11 and onto an separately provided screen 50. The image projected on the screen 50 is formed into a desired image by the projection optical system 10.

  In addition, the cam groove 12 provided in the lens barrel 11 enables movement of each projection lens in the optical axis direction, and zoom and focus adjustments are possible.

  Here, in the image projection apparatus 100 according to the present embodiment, the positional relationship among the light source 21, the projection optical system 10, the screen 50, and the main body installation surface 60 has a predetermined relationship described below. Specifically, for example, as shown in FIG. 2, the light source 21 is arranged so that the optical axis of the light beam emitted from the light source 21 is substantially parallel or parallel to the main body installation surface 60 of the image projection apparatus 100. Is. Further, the optical axis of the projection optical system 10 and the projection surface of the screen 50 are arranged so as to be substantially parallel or parallel to the normal direction of the main body installation surface 60.

  The configuration of the projection lens unit 15 will be described. The lens barrel 11 of the projection lens unit 15 holds a plurality of projection lenses constituting the projection optical system 10, and the lens barrel is placed outside (outer peripheral portion) of the lens barrel 11 holding each projection lens. A cam frame 13 provided with a groove (cam groove 12) for moving a part of 11 in the optical axis direction is provided. The cam frame 13 also constitutes a part of the lens barrel 11 and is made of, for example, a metal member.

  Various configurations can be adopted as the configuration of the lens barrel 11 inside the cam frame 13, and at least the projection lens has a configuration capable of adjusting the zoom and the focus and is brought into contact with the cam groove 12. A cylindrical optical axis positioning portion 14 that regulates the position in the optical axis direction is formed radially about the optical axis. That is, the optical axis positioning unit 14 is provided in the lens barrel 11 excluding the cam frame 13.

  At this time, as shown in FIG. 4, the optical axis positioning unit 14 is located on the lower side in the vertical direction (lower side in FIG. 4), that is, the end surface 12 a closest to the main body installation surface 60 in each cam groove 12. The end surface (vertical upper side surface) 12b is not in contact with the main body installation surface 60.

  Here, as described above, since the optical axis of the projection optical system 10 is arranged in parallel to the normal line of the main body installation surface 60, the image projection device 100 includes each projection lens that constitutes the projection optical system 10. The gravity acts on the main body installation surface 60 side by its own weight. For this reason, the end surface 12a of the cam groove 12 and the optical axis positioning part 14 can be contacted.

  According to such a configuration, it is possible to loosen the machining accuracy of the end face side (end face 12b) far from the main body installation surface 60 with respect to the cam groove 12 that conventionally requires high machining accuracy. Thereby, simplification of a processing process and reduction of processing cost can be realized.

  Further, since the end surface 12a of the cam groove 12 and the optical axis positioning portion 14 come into contact with each other due to the weight of each projection lens, the combination accuracy of the end surface 12a of the cam groove 12 and the optical axis positioning portion 14 is also reduced, and processing is performed. It is possible to suppress mistakes, eliminate rework to design, and facilitate the assembly of the cam groove 12 and the optical axis positioning unit 14. Therefore, it is possible to reduce processing costs and assembly costs, and lead time.

  The shape of the cam groove 12 formed in the cam frame 13 shown in FIGS. 4 and 5 and the position of the cam groove 12 can be variously configured depending on the configuration of the lens barrel 11 and the projection optical system 10. However, the present invention is not limited to the illustrated example.

(Second Embodiment)
Hereinafter, other embodiments of the image projection apparatus according to the present invention will be described. In addition, description about the same point as the said embodiment is abbreviate | omitted suitably.

  Moreover, it is preferable that the cam frame 13 and the lens barrel 11 that can be moved in the optical axis direction by the cam groove 12 formed in the cam frame 13 are made of a resin member.

  As described above, when the cam frame 13 is made of a metal member, precise machining is required when the cam groove 12 is formed. In addition to the effects of the first embodiment, the weight load generated when moving in the optical axis direction can be reduced, and the product life can be extended. Further, the material cost can be reduced by changing the metal member to the resin member.

(Third embodiment)
Further, it is preferable that the optical axis positioning portion 14 formed in the lens barrel 11 is constituted by a member different from the cam frame 13. For example, it is preferable to select a member having a small friction coefficient in relation to two members.

  According to such a structure, the friction which arises in the optical axis positioning part 14 and the end surface 12a of the cam groove 12 can be reduced, and lifetime improvement of a product can be implement | achieved.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Projection optical system 11 Lens barrel 12 Cam groove 12a End surface (lower side)
12b End face (upper side)
13 Cam frame 14 Optical axis positioning unit 15 Projection lens unit 20 Illumination optical system 21 Light source 22 Reflector 23, 24 Relay lens 25 Illuminance equalization means 26 Color wheel 30 Separation means 40 Image forming element 50 Screen 100 Image projection apparatus

JP 2004-93630 A Japanese Patent Laid-Open No. 10-68860

Claims (3)

A light source;
A projection optical system comprising a plurality of lenses for forming a light beam emitted from the light source into a desired image on the projection surface;
A lens barrel holding the projection optical system;
In an image projection apparatus having a main body structure that integrally holds them,
The optical axis of the light source is substantially parallel to the installation surface of the main body structure, and the projection surface and the optical axis of the projection optical system are normal to the installation surface of the main body structure. Deployed almost parallel,
The lens barrel is
A cam frame formed with a groove on its outermost part so that the lens barrel can move in the optical axis direction by rotating itself;
A cylindrical optical axis positioning portion that is in contact with the groove of the cam frame and is radially formed around the optical axis,
The optical axis positioning unit positions the optical axis positioning unit on the cam frame by contacting a groove end surface of the groove formed on the cam frame, which is closer to the installation surface of the main body structure. apparatus.   The image projection apparatus according to claim 1, wherein the cam frame and a lens barrel that is movable in an optical axis direction by a groove provided in the cam frame are made of a resin member.   The image projection apparatus according to claim 1, wherein the optical axis positioning unit is made of a member different from the cam frame.

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