JP2008058875A - Projection lens and image projection device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the projection field angle of a projection lens for an image projection device is normally fixed, however, when a distance between a projection screen and the image projecting device is fixed according to an indoor environment, projected images are made too large or small, resulting in inconvenience. <P>SOLUTION: Among lens groups composing the projection lens, at least one lens is divided into a plurality of areas of different powers. The image projection device which incorporates this projection lens and allows a change in projection field angle by rotating the projection lens, is provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a projection lens used in an image projection apparatus incorporating an electro-optical element and an image projection apparatus using the projection lens. In particular, the present invention relates to a projection lens having a plurality of projection angles of view at the opening surface of the projection lens.

  2. Description of the Related Art In recent years, image projection apparatuses incorporating an electro-optic element such as a liquid crystal display element or a DMD (digital micromirror device) display element have become widespread. This type of image projection apparatus is easy to carry, 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. For this reason, the optical axis of the projection lens of the image projection apparatus does not match the center of the projection screen.

  FIG. 6 is a schematic view of a conventionally known image projection apparatus 100 of this type. The image projection apparatus 100 includes a housing 101, an operation panel 103, a projection lens 102, a lens group 104 provided in the projection lens 102, and the like. FIG. 7 is a diagram for explaining the configuration and the optical path in the image projection apparatus 100. Light emitted from the light source 111 enters an electro-optical element such as the liquid crystal display element 112, and image light emitted from the liquid crystal display element 112 is emitted from the projection lens 113 and projected onto the projection screen 114. In this case, the optical axis 115 of the liquid crystal display element 112 is shifted downward from the optical axis 116 of the projection lens 113. The image light projected from the projection lens 113 is emitted from above the optical axis 116 of the projection lens 113 and enlarged and projected. In this way, the image light is incident after being shifted from the optical axis 116 of the projection lens 113 and is emitted from the position shifted from the optical axis 116 at the opening of the projection lens 113. This is because when a projector is placed on a desk and projected, an image is projected on the screen without being blocked by the desk or the like.

  FIG. 8 is a schematic diagram illustrating the configuration of the lens group of the projection lens 113. The first lens group 121 includes a first lens group 121 and a second lens group 122. The first lens group 121 is a focusing lens, and the second lens group 122 is a compensator lens, a relay lens, or the like. The liquid crystal display element 112 is installed below the optical axis of the second lens group 122 and emits image light toward the second lens group 122. The image light incident on the projection lens 113 passes below the optical axis 116 in the second lens group 122 and passes above the first lens group 121 and is enlarged and projected onto the projection screen 114. Therefore, in the first lens group 121, only the upper half is used.

In Patent Document 1, it is described that the projection lens is cut in half and accommodated in a semi-cylindrical barrel having a base. And when using the projection display device, project the image by protruding the lens barrel from the top of the housing of the projection display device, and when not using it, rotate the base so that the bottom of the lens tube is at the top, It is described that it does not protrude from the upper surface.
JP 2006-23361 A

  This type of image projection apparatus 100 carries an image projection apparatus and a projection screen, and installs them appropriately 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 projection apparatus, and the like are limited. When the projection angle of view of the image projection apparatus is fixed, in a room environment where the distance between the projection screen and the image projection apparatus is far, the projection image becomes too large and only a part of the image is displayed on the projection screen. There was a problem that it was displayed and the whole could not be seen. In addition, when the distance between the image projection device and the projection screen is too narrow, there is a disadvantage that the projected image becomes too small.

  Some projection lenses have a zoom mechanism and can change the projection angle of view. However, this type of projection lens requires a variator lens in addition to a focusing lens and a compensator lens, and because it uses a large number of lenses, the volume increases and the weight increases, making it easy to carry and set. Was disadvantaged. In addition, when changing the projection angle of view, there is a problem that a complicated and precise movable mechanism for moving these lens groups relative to each other is required.

  In the present invention, the following means have been taken in order to solve the above problems.

  According to the first aspect of the present invention, there is provided a projection lens for an image projection apparatus, wherein at least one lens constituting the projection lens is divided into a plurality of regions having different powers. It was.

  According to a second aspect of the present invention, the projection lens according to the first aspect is characterized in that the plurality of regions are regions divided into at least two parts around the vicinity of the optical axis.

  In the present invention according to claim 3, the plurality of regions are located in the vicinity of the optical axis and are divided into at least two by a plane substantially parallel to the optical axis. A projection lens was used.

  According to a fourth aspect of the present invention, there is provided the projection lens according to any one of the first to third aspects, wherein projection angles of view of images projected through the respective regions are different from each other.

  In this invention which concerns on Claim 5, the said at least 1 lens is a front lens, It was set as the projection lens of any one of Claims 1-4 characterized by the above-mentioned.

  In the present invention according to claim 6, the projection lens according to claim 5, wherein the at least one lens is a lens or a lens group adjacent to the front lens. It was.

  In this invention which concerns on Claim 7, the electro-optical element which converts the light which injected from the light source into image light, and the projection lens of any one of Claims 1-6 which expands and projects the said image light. The projection lens includes the projection lens that is incident at a position shifted from the optical axis of the projection lens and projects the image light in a direction shifted from the optical axis, and the projection lens or the projection. An image projection apparatus is characterized in that at least one lens constituting the lens can be arranged at a position rotated about the optical axis, and a plurality of regions having different powers can be used properly.

    In the present invention according to claim 8, the image projection apparatus according to claim 7, wherein the projection lens or at least one lens constituting the projection lens is configured to be rotatable by 180 °.

    The present invention according to claim 9 is characterized in that the image light does not cross a divided region that divides the at least one lens into a plurality of regions having different powers. An image projection apparatus was obtained.

  According to the projection lens of the present invention, at least one lens constituting the projection lens is divided into a plurality of regions having different powers. This has the advantage that a plurality of different types of projection images can be obtained without replacing the lens.

  In addition, since the projection lens is divided into at least two parts around the optical axis, the projection angle of view can be easily switched by rotating the lens around the optical axis. .

  Further, since 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, there is the convenience that the upper and lower halves can be used properly.

  In addition, since the projection angle of view of the image projected through each region is different, the projection angle of view can be easily switched by a simple mechanism when applied to an image projection apparatus in which light passes through a part of the lens. It has the convenience of being able to.

  In addition, since the lens having a plurality of regions with different powers is used as the front lens of the projection lens, there is an advantage that the rotation mechanism for rotating the lens can be simplified.

  Further, since the lens adjacent to the front lens is also divided, there is an advantage that the selection range of the projection angle of view can be widened.

  Further, since the image projection apparatus using the projection lens is used, the projection angle of view can be changed by a simple operation such as rotating the projection lens, for example, 180 °, and the light and compact image projection apparatus is convenient to carry. Can be provided.

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

  FIG. 1A is a schematic cross-sectional view showing a configuration of a wide-angle projection lens 1 that performs wide-angle projection, and FIG. 1B is a schematic cross-section showing a configuration of a narrow-angle projection lens 6 that performs narrow-angle projection. FIG. 1C is a schematic cross-sectional view showing the configuration of a multi-angle projection lens 7 including a lens having a plurality of regions having different powers according to the present embodiment. The same parts or parts having functions are denoted by the same reference numerals.

  In FIG. 1A, the wide-angle projection lens 1 includes a first lens group 3 and a second lens group 4. The first lens group 3 constitutes a focus lens group. The second lens group includes a compensator lens for correcting a focus shift, a relay lens for image formation, and the like. The image light emitted from the liquid crystal display element 2 passes through a region below the optical axis 5, passes above the optical axis of the first lens group 3, and is enlarged and projected upward at an angle of the projection field angle θa. Is done. A front lens lens Wa is provided on the forefront of the first lens group 3. The front lens lens Wa is a concave lens and has negative power.

  In FIG. 1 (b), the part different from FIG. 1 (a) is the front three lenses of the first lens group 3, 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 as compared with the lens Wa in FIG. The lens Nc has a relatively positive power as compared with the lens Wc in FIG. The projection angle of view θb of the narrow angle projection lens 6 is smaller than the projection angle of view θa of the wide angle projection lens 1.

  FIG. 1C shows an embodiment of the present invention. The front lens 8, the middle lens 9, and the rear lens 10 of the first lens group 3 are narrow-angle projection lenses 6 whose upper half from the optical axis 5 is narrow. The lower half of the optical axis 5 is the same as the front three lenses of the wide-angle projection lens 1. More specifically, the first three lenses of the first lens group 3 are divided into a plurality of regions having different powers. The front lens 8, which is a front lens, includes a region N′a that has a positive power above the optical axis 5 and a region W′a that has a negative power below the optical axis 5. The next middle lens 9 has a region N′b above the optical axis 5 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. It is smaller than the power of 'b. The next rear lens 10 includes a region N′c above the optical axis 5 and a region W′c below the optical axis 5, and the power of the upper region N′c is relatively lower. It is larger than the power of W′c. The upper and lower divisions are located in the vicinity of the optical axis 5 and are divided by a plane substantially parallel to the optical axis 5.

  As a result, the image light incident from below the optical axis 5 of the second lens group 4 is projected at a narrow angle by the projection angle of view θa. On the other hand, when the liquid crystal display element 2 ′ is disposed above the optical axis 5, the projection is performed below the optical axis 5 with a larger projection angle of the projection angle of view θa. Similarly, when the liquid crystal display element 2 is fixed and the multi-angle projection lens 7 is rotated by 180 ° about the optical axis 5, the projection field angle θb can be easily switched to the projection field angle θa. In this case, the image light that has passed through the liquid crystal display element 2 is prevented from crossing the divided areas that are vertically divided. Thereby, the projected image light can be prevented from being unnaturally divided.

  In the above description, the first three lenses of the first lens group 3 are divided into a plurality of regions having different powers, but any one lens can be divided into a plurality of regions. For example, only the front lens 8 that is the front lens can be used by being divided into a plurality of regions. In the above description, an example in which one lens is divided into two parts has been described. However, the present invention is not limited to this, and one lens can be divided into three parts or more.

  In addition to the case where one color liquid crystal display element is used as the liquid crystal display element 2, a liquid crystal display element using three liquid crystal display elements for displaying each color of R (red), G (green), and B (blue) is used. Can be used. For example, light from a light source is divided into three by a dichroic mirror, and each of the divided light beams is passed through an RGB color filter, and the colors corresponding to three liquid crystal display elements that display R, G, and B colors are displayed. You may make it irradiate with a light beam and synthesize | combine the image light of each color radiate | emitted from each liquid crystal display element, and may inject into a 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.

  Further, a DMD (digital micromirror device) display element can be used instead of the liquid crystal display element. In a DMD display element, fine mirrors are two-dimensionally arranged on a semiconductor substrate, the angle of each mirror is changed according to an image signal, and when the light incident on the DMD is reflected, the reflected light forms an image. . In the image projection apparatus, the light flux from the light source is time-divided into each color of RGB 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 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. 2A is a schematic cross-sectional view of a lens used in the present embodiment, and FIG. 2B is a schematic plan view. Centering on the optical axis 5 of the multi-angle projection lens 7, the upper half has a region N'x and the lower half has a region W'x. In this case, the upper half lens has positive power and the lower half has negative power. When this lens is used as a front lens, the upper half with positive power has a smaller projection angle of view than the lower half. The radius of the upper half lens is smaller than the radius of the lower half lens. However, the lens radii do not necessarily have to be formed differently, and if they can be manufactured, the upper and lower sides can have the same radius. Such a lens was cut by cutting a normal glass lens having an upper half lens power and a normal glass lens having a lower half lens power, and then cutting across the optical axis. Each is formed by bonding so that the optical axes coincide. Alternatively, a mold having the shape shown in FIG. 2 is prepared, and a transparent plastic material, for example, a lens material made of transparent polycarbonate resin (PC), polymethyl methacrylate, acrylic resin (PMMA), or the like is poured into the mold. It can be formed integrally by pressing the mold. Further, when the material is glass, it can be configured to be fixed to a lens barrel that holds the lens in a state of being separated without being bonded to each other.

  FIG. 3 is a schematic cross-sectional view of a projection lens 30 in which the multi-angle projection lens 7 incorporating the lens formed as described above is incorporated in a lens barrel. The same reference numerals are assigned to the same parts or the same functions.

  A fixed cylinder 31 and a movable cylinder 33 are inserted into the outer barrel 32. Some lenses of the second lens group 4 and the first lens group 3 are fixed to the fixed cylinder 31 by the holding portion 35. A front lens 8, a middle lens 9, and a rear lens 10 of the first lens group 3 are fixed to the movable tube 33. These lenses have two regions with different powers around the optical axis. A rotating knob 34 is provided outside the movable cylinder 33. The movable cylinder 33 is rotatably fixed to the outer lens barrel 32. The liquid crystal display element 2 is disposed below the optical axis 5, and the projection lens is irradiated with image light from below the optical axis 5. In the area of the first lens group 3, the incident image light passes through the upper lens area from the optical axis 5 and is projected from the upper area from the optical axis 5 of the front lens 8. When the movable cylinder 33 is rotated 180 ° by the rotary knob 34, the front lens 8, the middle lens 9 and the rear lens 10 are turned upside down, and the projected field angle is changed. Between the outer barrel 32 and the movable barrel 33, there is a mechanism in which a stopper works every 180 ° rotation by a stopper (not shown).

  In the above embodiment, the movable cylinder 33 is rotatably inserted into the outer lens barrel 32. However, the movable cylinder 33 is not necessarily configured to be rotatable. After the movable cylinder 33 is once removed and rotated 180 degrees. You may make it insert.

  In the above example, the three lenses have a plurality of regions with different powers, and the three lenses are rotated. The movable lens may have a plurality of areas. In addition, the structure can be simplified by rotating only the front lens of the front lens 8 with a plurality of regions. Alternatively, all the lenses of the first lens group 3 and the second lens group 4 may be fixed to the movable cylinder, and the entire lens may be rotated with respect to the fixed cylinder. Further, the movable cylinder 33 can be electrically rotated by a stepping motor or the like. This is convenient when operating the image projection apparatus from a distance.

  FIG. 4 is an overview diagram showing an image projection apparatus 40 incorporating the projection lens 30 shown in FIG. 3 and a PC terminal 45 that transmits image data to the image projection apparatus 40. The image projection device 40 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 stores these elements in a housing 41. An operation panel 42 is provided on the upper surface of the housing 41, and a projection lens 30 is provided on a side surface of the housing 41. The movable tube 33 of the projection lens 30 is provided with a rotation knob 34 on the outer periphery thereof and can be manually rotated.

  5 shows a state in which an image is projected by the image projection device 40 shown in FIG. 4, FIG. 5 (a) shows a case where the projection field angle is small, and FIG. 5 (b) shows a case where the projection field angle is large. Each is shown. FIG. 5A shows a state in which an image from the liquid crystal display element is projected by rotating the rotary knob 34 provided on the movable cylinder 33 of the projection lens 30 upward. The image light emitted from the liquid crystal display element passes through the upper half area of the first lens group 3 and is projected with a projection angle of view θb. This is appropriate when the distance between the screen 50 and the image projection device 40 is large. FIG. 5B shows a projection state when the rotary knob 34 is rotated 180 ° and fixed downward. Image light emitted from the liquid crystal display element is projected at a large angle of projection angle θa. This case is appropriate when the distance between the screen 50 and the image projection device 40 is small.

  Thus, 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 in accordance with the environment in which the image is projected.

It is a projection lens typical sectional view concerning an embodiment of the invention. It is typical sectional drawing of the lens used for embodiment of this invention. It is a typical sectional view of a projection lens concerning an embodiment of the invention. 1 is an overview of an image projection apparatus according to an embodiment of the present invention. It is a figure showing the state which is projecting the image with the image projector which concerns on embodiment of this invention. It is an outline figure of a conventionally well-known image projection device. It is a conceptual diagram for demonstrating the structure of a conventionally well-known video projection apparatus. It is a schematic diagram showing the lens group structure of a conventionally well-known projection lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wide angle projection lens 2 Liquid crystal display element 3 1st lens group 4 2nd lens group 5 Optical axis 6 Narrow angle projection lens 7 Multiple angle projection lens 8 Front lens 9 Middle lens 10 Rear lens

Claims (9)

  A projection lens for an image projection apparatus, wherein at least one lens constituting the projection lens is divided into a plurality of regions having different powers.   The projection lens according to claim 1, wherein the plurality of regions are regions divided into at least two parts around the vicinity of the optical axis.   The projection lens according to claim 2, wherein the plurality of regions are located in the vicinity of the optical axis and are divided into at least two by a plane substantially parallel to the optical axis.   The projection lens according to any one of claims 1 to 3, wherein projection angles of view of images projected through the respective regions are different from each other.   The projection lens according to claim 1, wherein the at least one lens is a front lens.   The projection lens according to claim 5, wherein the at least one lens is a lens or a lens group adjacent to the front lens. An image projection apparatus comprising: an electro-optic element that converts light incident from a light source into image light; and the projection lens according to any one of claims 1 to 6 that magnifies and projects the image light.
The projection lens enters the image light at a position shifted from the optical axis of the projection lens, and projects the image light in a direction shifted from the optical axis.
The projection lens or at least one lens constituting the projection lens is configured to be arranged at a position rotated around the optical axis, and a plurality of regions having different powers can be used properly. Image projection device.   The image projection apparatus according to claim 7, wherein the projection lens or at least one lens constituting the projection lens is configured to be rotatable by 180 °.   The image projection device according to claim 7 or 8, wherein the image light does not cross a divided region that divides the at least one lens into a plurality of regions having different powers.

Images