JPH0996775A - Image projection device with trapezoidal distortion correction function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct a trapezoidal distortion by constituting so that a correction lens for trapezoidal distortion is rotated around the central axial line in the horizontal direction passing through a section of its mirror surface upward or downward within a prescribed angle. SOLUTION: The image projecting device is provided with a light source assembly 110, an image generation assembly 120 containing an image generation plane and the correction lens of the trapezoidal distortion and a projection objective lens 130 containing one or plural lenses. Among them, the light source of the light source assembly 110 emits light to irradiate the image generation plane of the image generation assembly 120 uniformly. Further, the main axial line of the light outgoing from the light source assembly 110 is aligned with the central axial line of the image generation plane in the perpendicular direction, and the optical main axis of the projection objective lens 130 is aligned with the perpendicular central axial line of the image generation plane, too. Further, the correction lens for trapezoidal distortion is made rotatable around the central axial line in the horizontal direction in an mirror surface upward or downward within the prescribed angle.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a trapezoidal strain (Keyston
The invention relates to an image projection device having a correction function of (e distortion), and particularly to an image projection device capable of correcting trapezoidal distortion when the projection angle is out of the effective range with a simple mechanism and a simple operation method. Is.

[0002]

BACKGROUND OF THE INVENTION Liquid crystal projection devices are often already used to display computerized material in displaying commercial information. Computers, especially notebook computers, are widely used by business people, and it is necessary to project multimedia image information displayed on the computer screen directly onto the screen and at the same time show it to people. . Such multimedia display materials can be easily and quickly created using commercially available software.

[0003]

The image projection apparatus uses a liquid crystal display, receives image information from a computer or a television, displays the above image material on the liquid crystal display, and further utilizes a light source to display an image on the liquid crystal display. To the target screen. Usually, in such an image projection apparatus, the problem of trapezoidal distortion correction cannot be avoided. This is because the projection device is not always placed and used in the most ideal position, and the image projection device may be brought in and used in a place such as a conference room. In such a case, the projection device may move a considerable angle of inclination (inclination angle) from the vertical axis of the plane of the target image screen in the conference room.
e) may be placed. That is, the position where the projection device is placed is not always on the vertical center plane of the target image screen. Further, in many cases, the image is projected on the target image screen in an elevation angle state.
If there is no trapezoidal distortion correction device, the image distortion is unavoidable because the trapezoidal distortion always occurs in the image projection performed at a position at an angle of inclination from the vertical axis of the plane of the target image screen. On the other hand, when the position where the projection device is placed is in the vertical plane of the target image screen, but the position is lower than the vertical central axis of the target image screen, the image displayed on the target image screen has a narrower bottom width than the upper width. It becomes a thing, and a square building becomes a symmetrical square like a trapezoid. Further, if the projection device is offset from the central vertical plane of the target image screen, the image on the target image screen will be a completely asymmetric quadrilateral.

In order to correct the trapezoidal distortion in the above-mentioned projection device, in the prior art, a method of correcting the trapezoidal distortion phenomenon by translating the projection objective lens of the projection device has been proposed. However, the range of applications of this method is limited. That is, when the position where the projection device is placed has a large inclination angle from the central axis of the projection objective lens in the vertical direction, the projection objective lens is moved unless the projection objective lens of the projection device has a very large aperture. The range that can be done is relatively narrow. However, a large-diameter projection objective lens increases the size of the entire apparatus and increases the manufacturing cost. It has also been proposed to correct the trapezoidal distortion by moving the projection light source. But,
In general, a circuit such as a power supply line is connected to the light source, and the distance to an image generator such as a liquid crystal display is relatively short, and its implementation requires a relatively complicated mechanism and relatively high manufacturing cost. The movement of the light source is another problem in the case of a projection device that produces an image on a liquid crystal display. That is, the viewing angle of view of a traditional liquid crystal display panel is usually quite limited. The liquid crystal display panel has a dim image contrast and cannot be clearly seen unless viewed within a limited angle from a central axis line in the vertical direction of the plane. This viewing angle problem limits the irradiation angle of the light source in the liquid crystal projection device.

A first object of the present invention is to provide an image projection device having a trapezoidal distortion correction function. The image projection device can correct the trapezoidal distortion even when the image projection device has a considerable inclination angle. A second object of the present invention is to provide an image projection apparatus having a very simple trapezoidal distortion correction function. The third object of the present invention is extremely simple and effective,
Provided is an image projection device having a function of correcting trapezoidal distortion.

[0006]

SUMMARY OF THE INVENTION The present invention provides an image projection device capable of projecting an image onto a target image screen. The image projection apparatus includes a light source assembly including a light source capable of illuminating in the direction of a projection ray in the projection apparatus, an image generation assembly including an image generation plane, and a trapezoidal distortion correction lens, and a projection including one or more lenses. And an objective lens. The light source of the light source assembly emits light to illuminate the image generation plane of the image generation assembly evenly, and the main axis of the light emitted from the light source assembly is the vertical central axis of the image generation plane. Coincident with each other, the optical principal axis of the projection objective lens also coincides with the vertical center axis of the image generation plane, and the trapezoidal distortion correcting lens has a horizontal central axis in a cross section of its mirror surface as an axis of rotation, and an upper or lower side. It can rotate within a predetermined angle in any direction. In another aspect of the present invention, the correction lens for trapezoidal distortion can rotate within a predetermined angle toward a left or right direction with a vertical central axis passing through a cross section of the mirror surface as a rotation axis. Image projection device.

[0007]

1 is a drawing showing a light projection path in an image projection apparatus according to an embodiment of the present invention. As shown in FIG. 1, the image projection apparatus of the present embodiment generally includes a light source assembly 110, an image generation assembly 120, and a projection objective lens 130. The light source assembly 110 includes a light source 111, a spherical reflecting mirror 114, and an aspherical condenser lens 115. The function of the spherical reflecting mirror 114 and the aspherical condenser lens 115 is to appropriately send the light emitted from the light source assembly 110 to the image generating assembly 120. The image generation assembly 120 shown in FIG.
(For example, a liquid crystal display), a front Fresnel lens 122, and a rear Fresnel lens 123.
Note that the image generator 121, the front Fresnel
Lens 122 and rear Fresnel lens 123 are now parallel to each other. It is obvious to a person skilled in the art that the Fresnel lens can appropriately project the light rays passing through it into a predetermined focal point. In the embodiment of FIG. 1, the rear Fresnel lens 123 causes the light source assembly 110 to generate and aspherical condenser lens 115.
The light passing through illuminates the image generator 121 evenly.

The image generator 121 receives an image signal from an image source such as a multimedia computer or a television, and outputs an image to be projected to the image generator 1.
21 image display planes can be generated. The light from the light source assembly 110 is transmitted to the image generation assembly 120.
When the image generator 121 is evenly illuminated by passing through the rear Fresnel lens 123, the image generated on the image display plane passes through the front Fresnel lens 122 and is projected forward, so that the projection objective It is sent to the lens 130. As shown in FIG. 1, the projection objective lens 130 is a lens including a plurality of lenses 131, 132, 133, etc.
It is an assembly. The lens assembly receives an image generated by the image generation assembly 120 and illuminated by the light of the light source assembly 110, and adjusts the focal length of the projection objective lens 130 to adjust the image to be projected to a predetermined target image. Screen (not shown)
, So that it is in focus. In the embodiments described above, the image generation assembly 120 generates an image for projection. The light source 110 emits sufficient light to illuminate the image produced by the image producing assembly 120. The projection objective 130 causes the light source 110 to project the image obtained by illuminating the image generation assembly 120. Thus, the target image can be projected into focus on a target image screen (not shown).

In the image projection apparatus of FIG. 1, the projection paths of the light are on the same straight line. That is, both the emission point of the light source 110 and the projection objective lens 130 are provided on the central axis in the vertical direction of the image generation plane of the image generation assembly 120. The image projected by the above arrangement does not cause trapezoidal distortion. However, this ideal projection angle is a special situation, and the position of the projection is usually at a tilt angle from the vertical axis of the target image screen plane. As described above, the special structure according to the present invention can correct the trapezoidal distortion. FIG. 2 shows a state in which the light projection path in FIG. 1 is changed, and shows a case where the light projection path makes an elevation angle of 12 degrees with the central axis of the target image screen. is there. The image projection apparatus of the embodiment shown in FIG. 2 generally includes a light source assembly 210, an image generation assembly 220, and a projection objective lens 230. As in the embodiment of FIG. 1, this embodiment has a light source assembly 210 including a light source 211 such as a halogen lamp, a spherical reflecting mirror 214, and an aspherical condenser lens 215, as shown in FIG. Light source assembly 210 including the three parts
Suitably directs the generated light to the image generation assembly 220.

Similar to the embodiment of FIG. 1, the image generation assembly 220 shown in FIG. 2 includes an image generator 221, such as a liquid crystal display, a front Fresnel lens 222, and
A rear Fresnel lens 223. In the embodiment of FIG. 2, the rear Fresnel lens 223 evenly illuminates the image generator 221 with light from the aspherical lens 215 of the light source assembly 210. The image generator 221 receives the image signal and outputs an image to be projected to the image generator 221.
To the image display plane. The light from the light source assembly 210 is reflected by the rear Fresnel of the image generation assembly 220.
When passing through the lens 223 and illuminating the image generator 221, the entire image produced in the image display plane is projected forward through the front Fresnel lens 222 and sent to the projection objective 230. However, at this time, the plane of the front Fresnel lens 222 is set to the target image screen 24.
Adjusted so that it is parallel to 0, the upper edge of the image generator 221 faces rearward and is 12 with respect to the front Fresnel lens.
Can be tilted to form an elevation. Light source assembly 2
Light from 10 was generated by the image generator 221 as it passed through the rear Fresnel lens 223 of the image generation assembly 220 and evenly through the image generator 221 with an elevation angle of 12 degrees rearward. The entire image is captured by the front Fresnel lens 222 parallel to the target image screen 240.
It is projected forward and sent to the projection objective lens 230. At this time, the axis of the projection light from the front Fresnel lens is inclined upward.

As shown in FIG. 2, the projection objective lens 230.
Is composed of a plurality of lenses 231, 232, 233 and the like. These lenses are the image generation assembly 220.
Occurs, and receives the image illuminated by the light source assembly 210. By adjusting the focal length of the projection objective lens 230, the image to be projected is displayed on the target image screen 24.
The image is projected on 0 so that it is in focus. In the embodiment of FIG. 2, the front Fresnel lens 222 is directed forward 1
It is adjusted to incline by 2 degrees. That is, the front Fresnel
The projection optical axis of the entire image in the image projection device is tilted upward by about 12 degrees so that the lens 222 is parallel to the target image screen 240. That is, with the image projector tilted upward by 12 degrees, the vertical target image screen 240 is projected, and the front Fresnel lens 222 tilts the image generation surface of the image generator 221 downward by about 12 degrees. Therefore, the equivalent result is that the tilt angles for the front and the rear are mutually compensated, and the effect of correcting the trapezoidal distortion is obtained. In the embodiment of FIG. 2, the front Fresnel lens 222 can be adjusted so that the horizontal center horizontal axis is the axis of rotation and the vertical center axis of the lens plane is inclined vertically.

Further, when the central axis of the front Fresnel lens 222 in the vertical direction is used as the axis of rotation and it is rotatable leftward or rightward with respect to the projection optical axis, an image projection provided with such a front Fresnel lens is provided. The device can simultaneously correct for trapezoidal distortion due to vertical and horizontal tilt angles about the vertical center axis of its corresponding target image screen. Next, reference is made to FIG. FIG. 3 shows a projection path of light in an image projection device according to another embodiment of the present invention. In this embodiment, the target light projection path is arranged at an elevation angle with the vertical center axis of the target image screen. The embodiment shown in FIG. 3 has the same basic mechanism as the embodiment of FIG. A specific difference is that a reflecting mirror 351 is inserted between the light source assembly 310 and the image generating assembly 320,
Also, the image generation assembly 320 and the projection objective lens 33.
That is, the reflecting mirror 352 is inserted between 0 and 0. Since the reflecting mirrors 351 and 352 are simple plane mirrors, by installing them, the entire plane projection device can be housed in a smaller space, and the size can be reduced.
Meanwhile, the light source assembly 310 may use a light source that emits light having an infrared wavelength, such as a halogen lamp.
Therefore, the plane reflecting mirror 35 close to the light source assembly 310 is used.
By adopting the cold-light mirror that does not reflect the light having the wavelength in the infrared region as 1, the infrared ray which is not visible light can be prevented from being sent to the image generator 321. This is effective when the image generator 321 is a liquid crystal display panel that operates at a low temperature.

As shown in FIG. 3, when the projection tilt angle of the projection objective lens 330 of the embodiment of the image projecting apparatus of the present invention is 12 degrees upward, in the image generating assembly 320, the front Fresnel Lens 32
The vertical central axis in the plane of
The vertical central axis in the plane 1 is also adjusted so as to be tilted downward by 12 degrees, and thus the upward tilt angle in the projection device is compensated. Therefore, the image projection apparatus of the present invention uses a simple structure and can eliminate the trapezoidal distortion due to the tilt angle at the position where the projection apparatus is placed. Since the apparatus of the present invention can eliminate trapezoidal distortion due to the tilt angle in the horizontal direction in addition to eliminating trapezoidal distortion due to the projection angle in the vertical direction, that is, in the elevation direction, the range of use of the projection apparatus is wide. Further, since the trapezoidal distortion can be erased with only one or two sets of simple tilt adjusting push rods, the cost can be reduced as compared with the erasing means in the conventional technique. Besides, the person skilled in the art should not limit the invention to a projection device in which the planar projection device is equipped with a backlight such as a liquid crystal display plate, as long as the screen of the television or monitor which itself emitted the image light source (in this situation It will be appreciated that all of the above are also applicable). All such modifications are also included in the scope of the present invention.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a light projection path of an image projection device according to one embodiment of the present invention, the light projection path having a vertical relationship with a target image screen.

2 is another embodiment of FIG. 1, in which the light projection path forms an elevation angle with the vertical central axis of the target image screen, ie, the image projection device is lower than the target image screen. It is drawing which shows the state placed in a position.

FIG. 3 is a drawing showing a light projection path of an image projection apparatus according to another embodiment of the present invention, and the target light projection path forms an elevation angle with a vertical central axis of the target image screen.

[Explanation of symbols]

 110, 210, 310 light source assembly 111, 211, 311 light source 112, 212, 312 virtual image of light source 113, 213, 313 center of curvature of spherical reflecting mirror 114, 214, 314 spherical reflecting lens 115, 215, 315 aspherical condensing mirror 120, 220, 320 Image generation assembly 121, 221, 321 Image generator 122, 222, 322 Front Fresnel lens 123, 223, 323 Rear Fresnel lens 130, 230, 330 Projection objective lens 240, 340 Target image screen 351 , 352 plane mirror

[Procedure amendment]

[Submission date] October 3, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (19)

[Claims] 1. A light source assembly capable of illuminating a direction of a projection light path in an image projection apparatus, an image generation assembly including an image generation plane and a trapezoidal distortion correction lens, and a projection including one or more lenses. An image projection apparatus including an objective lens, wherein the light source of the light source assembly emits light to illuminate the image generation plane of the image generation assembly uniformly, and the correction lens for the correction distortion passes through a cross section of its mirror surface. Corrects the distortion of the projected screen due to the vertical tilt angle with respect to the vertical center axis of the target image screen by rotating the horizontal central axis as the rotation axis and turning it up or down within the planned angle An image projection device characterized by: 2. The trapezoidal distortion correction lens has a vertical central axis passing through a cross section of its mirror surface as a rotation axis, and rotates leftward or rightward within a predetermined angle to thereby obtain the target image screen. The image projection apparatus according to claim 1, wherein the trapezoidal distortion of the projection screen due to the inclination angle in the left-right direction with respect to the vertical center axis line is corrected. 3. The image projection system according to claim 2, wherein the light source assembly includes a spherical reflecting mirror, and the light source is installed at a position near the center of curvature of the spherical reflecting mirror. apparatus. 4. The light source assembly includes an aspherical condenser lens, the aspherical condenser lens is focused on the light emitted by the light source and uniformly illuminates the image generation plane of the image generation assembly. The image projection device according to claim 3, wherein 5. The image projection device of claim 2, wherein the image generation assembly includes a rear lens disposed between the image generation plane and the light source assembly. 6. The image projection device according to claim 5, wherein the rear lens is a Fresnel lens. 7. The image projection apparatus according to claim 2, wherein the trapezoidal distortion correction lens is a Fresnel lens. 8. The image projection apparatus according to claim 2, wherein the image generation plane is a display plane formed of a liquid crystal display. 9. A flat mirror inserted between the light source assembly and the image generating assembly, wherein the light emitted by the light source assembly is a reflection of the flat mirror to even out the image generating plane of the image generating assembly. The image projection device according to claim 2, wherein the image projection device irradiates the image projection device. 10. The image projection apparatus according to claim 9, wherein the plane mirror is a cold reflecting mirror that does not reflect infrared rays. 11. A second plane mirror inserted between said image generating assembly and said Fresnel lens, and light passing through said image generating assembly reaches said Fresnel lens by reflection of said second plane mirror. The image projection apparatus according to claim 9, wherein 12. The image projection method according to claim 11, wherein the light source assembly includes a spherical reflecting mirror, and the light source is installed at a position near the center of curvature of the spherical reflecting mirror. apparatus. 13. The light source assembly includes an aspherical condenser lens, the aspherical condenser lens focuses light emitted from the light source, and uniformly illuminates the image generation plane of the image generation assembly. The image projection apparatus according to claim 12, wherein the image projection apparatus is configured to: 14. The image projection device of claim 11, wherein the image generating assembly includes a rear lens disposed between the image generating plane and the light source assembly. 15. The image projection apparatus according to claim 14, wherein the rear lens is a Fresnel lens. 16. The image projection apparatus according to claim 11, wherein the trapezoidal distortion correction lens is a Fresnel lens. 17. The image projection apparatus according to claim 11, wherein the image generation plane is a display plane formed by a liquid crystal display. 18. An image generation assembly including an image generator capable of emitting light and a trapezoidal distortion correction lens; and a projection objective lens including one or more lenses.
In an image projection device capable of projecting an image on a target image screen, the trapezoidal distortion correction lens has a central axis in the horizontal direction passing through the cross section of its mirror surface as a rotation axis, and a predetermined angle toward the upper or lower direction. An image projecting device characterized by correcting the trapezoidal distortion of a projection screen due to a tilt angle in a vertical direction with respect to a vertical central axis of a target image screen by rotating the target image screen within the range. 19. The trapezoidal distortion correction lens has a horizontal central axis passing through a cross section of its mirror surface as a rotation axis, and rotates leftward or rightward within a predetermined angle to thereby obtain a target image screen. The image projection apparatus according to claim 18, wherein the trapezoidal distortion of the projection screen due to the tilt angle in the left-right direction with respect to the vertical center axis is corrected.