JPH0378718A - Projecting device - Google Patents

Abstract

PURPOSE:To make the device small in size and light in weight and to reduce the cost of the device by providing a correcting means for optically correcting the size of at least one projected image. CONSTITUTION:Each image formed on each liquid crystal panel 8a - 8c is illuminated with each color illuminating light whose color is separated by each dichroic mirror 4 - 6, on the other hand, the image light is made incident on a projecting lens 12 after the colors are synthesized by a color synthesizing optical system 11, and the color image is enlarged and projected on a screen 13. And the correcting means 9a and 9b are constituted of at least two lens groups of a 1st lens group 14 and a 2nd lens group 15 having different refracting power. And in the case that a registration error occurs, the space between the two lens groups 14 and 15 is changed and adjusted so that the size of each image may agree with the size of reference green light, that means, the registration adjustment is performed. Thus, the increase of the cost, the weight and the size are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a projection device that synthesizes a plurality of images to create a projected image, and particularly relates to a technology related to its optical system.

[Prior Art] Projection devices that combine multiple images with certain color components to obtain, for example, a color image are well known;
It can be classified into several categories.

FIG. 8 shows a system called the three-tube, three-lens system. Braun tube with blue, green, and red light emission 39.40.4
The images emitted from 1 are enlarged and projected onto a screen 13 via corresponding projection optical systems 12 to obtain a color image.

FIG. 9 shows a system called the three-tube-lens system. Braun tube with blue, green, and red light emission 39.40.4
Three-color images emitted from the image forming apparatus 1 are combined by a color synthesis optical system 11 having a built-in half mirror, and enlarged and projected onto a screen 13 via a single projection optical system 12 to obtain a color image.

FIG. 10 shows a method called the three-panel lens method. White light emitted from an illumination optical system consisting of a reflecting mirror 1, a light source 2, and a condensing lens 3 is transmitted to color separation optical systems 4, 5, 6.
The light is separated into three colors of blue light, green light, and red light, and after being irradiated with a light valve (liquid crystal element) 8 and subjected to image modulation, each separated light is constituted by a color synthesis optical system 11, and then a projection optical system. An image is projected onto a screen 13 via 12.

[Problems to be Solved by the Invention] However, although it is ideal for a projection lens to project and depict the original picture as it is, in reality it is affected by aberrations generated by the projection lens. Therefore, especially when combining the above-mentioned different color components to obtain a color image, it is necessary to sufficiently correct the chromatic aberration remaining in the projection optical system, especially the chromatic aberration of magnification. If chromatic aberration of magnification remains, a so-called registration error will occur in which the three color lights are separated on the screen 13, leading to a decrease in resolution and image quality.

On the other hand, in a projection device that uses a cathode ray tube to obtain a color image, especially as shown in FIGS. 9 and 10,
It is relatively easy to electrically change the size of the image projected on the cathode ray tube itself 39, 40° 41, respectively, and it is also possible to correct the lateral chromatic aberration remaining in the projection optical system to some extent. .

However, in the method of obtaining color images using a liquid crystal panel, it is difficult to change the screen size.

On the other hand, although it is possible to correct aberrations to a certain extent from the standpoint of lens installation, such as by using an achromatic lens in the projection optical system or by increasing the number of lenses, there are limits to this. At the same time, practical problems arise, such as increased cost, increased weight, and increased size.

The present invention aims to solve such problems.

[Means for Solving the Problems] The present invention is characterized in that, in a projection device that combines a plurality of images having different color components and projects the image through a projection optical system, The present invention includes a correction means for optically correcting the size of at least one image, and more specifically, a correction means for optically correcting the size of at least one image. In a projection apparatus comprising an image forming means for forming a plurality of images, a combining means for combining images of each of the image forming means, and a projection optical system for projecting the combined image, the image forming means and the and a control means for controlling a magnification ratio of the variable magnification optical means so that the image projected by the projection optical system substantially matches the variable magnification optical device disposed between at least one of the optical system and the combining device. It's what I did.

[Example] The present invention will be explained in detail below with reference to the drawings.

2 is a light source such as a halogen lamp, xenon lamp, or metal halide lamp, 1 is a reflecting mirror, 3 is a condenser lens, 4 is a first dichroic mirror that reflects only the blue light component around 480 mm, and 5 is only the green light component around 540 mm. a second dichroic mirror that reflects 6
is a third dichroic mirror that reflects only the red light component around 600 mm, 7 is a reflective mirror consisting of a mirror surface, 8
Reference numerals a, 8b, and 8c are light valves (liquid crystal panels) that form original images, and 9a and 9b are correction means for optically correcting color shift, which have a configuration to be described later. Reference numeral 10 denotes an optical element that is optically equivalent to the correction means 9a and 9b in the standard state (before correction). Reference numeral 11 denotes a color synthesis optical system, which is composed of a cross dichroic prism in which two dichroic mirrors are orthogonally crossed. 12 is a projection optical system consisting of a zoom lens, and 13 is a screen.

The above configuration is applied to each liquid crystal panel 8a, 8. The multi-images formed in b and 8c are each dichroic mirror (4, 5, 6)
The images are illuminated with illumination light of each color separated by color, which is combined by a color combining optical system 11, and then enters a projection lens 12, where the color image is enlarged and projected onto a screen 13.

FIG. 2 is a diagram specifically showing the above-mentioned correction means 9a and 9b. The correcting means 9a and 9b are composed of at least two lens groups, a first lens group 14 and a second lens group 15, which have different refractive powers. If a difference in the relative image size occurs in the projected image due to chromatic aberration of the projection lens itself, especially lateral chromatic aberration, that is, if it arises from a registration error, there will be two problems. The distance between the lens groups is changed (as shown by arrow 16) to make the size of each machine match that of the standard green light, that is, registration adjustment is performed.

In addition, in this embodiment, the correction means is moved integrally in the optical axis direction (as shown by arrow 17) to perform focus adjustment, and is further moved in a direction intersecting the optical axis (as shown by arrow 18). ) The position of the projected image on the screen for the blue and red lights is made to match that for the green light (adjustment of misalignment).

Note that, instead of the operations shown by arrows 17 and 18, the same effect can be obtained by supporting the light valve on a moving mechanism and moving the light valve 8 in a direction parallel to or perpendicular to the optical axis. be able to.

Next, FIG. 3 shows an embodiment in which the correction means is constructed in a different form. In this embodiment, an example is shown in which the correction means is made of transparent elastic or fluid material such as silicone rubber. 1
Reference numeral 9 is a fluid substance enclosed within the transparent elastic membrane 21 . By adjusting the pressure via the cylinder 22, the curvature of the transparent elastic film changes, so the refractive power changes and the magnification can be changed. The imaginary edge indicated at 20 indicates the position of the transparent elastic membrane in the equilibrium state. Note that FIG. 3(A) shows a state in which pressure is applied, and FIG. 3(B) shows a state in which pressure is reduced.

Next, another embodiment will be shown based on FIG.

In this embodiment, an example using a known element whose focal length changes by applying a voltage from a power supply 26 to a transparent thin film electrode 24 that supplies power to a transparent dielectric 23 is used as a correction means. show.

This element is already known from, for example, Japanese Patent Application Laid-Open No. 57-19216 or Japanese Patent Application Laid-Open No. 59-78317. Briefly, by applying a voltage to the transparent thin film electrode 24 from the power supply 26, the refractive index of the transparent dielectric 23 changes in the direction perpendicular to the optical axis, and the characteristic diagram shown in FIG. 6 (vertical axis n is the refractive index, horizontal The element has a characteristic of having a refractive index distribution as shown by a curve 29, where the axis R is a distance from the center of the transparent dielectric 23 in a direction perpendicular to the optical axis.

Therefore, a magnification change effect similar to that obtained by the operation 16 shown in FIG. 2 can be obtained, and a color image with good image quality can be obtained.

By the way, especially when the projection optical system is a zoom lens, the lateral chromatic aberration characteristics vary depending on the focal length.
Next, focusing on this point, an embodiment aimed at obtaining even better images will be described.

In FIG. 6, the horizontal axis represents the zooming focal length f of the projection optical system 12.
1 is a characteristic diagram showing a magnification variation curve 31 of blue light and a magnification variation curve 32 of red light with the projection magnification (straight line 35) of green light as a reference in a graph in which the vertical axis is the magnification β.

The basic operation and configuration of this embodiment using a projection optical system having characteristics of variation in chromatic aberration of magnification due to zooming as shown in FIG. 8 will be explained with reference to FIG. 7. FIG. 7 shows a configuration in which the portion from the light valve 8 to the projection optical system 12 for one of the three colors of light, for example, blue light, in FIG. 1 is replaced with the configuration of this embodiment. As the correction means 9, the device shown in FIG. 2 used in the first embodiment is used, and as the projection optical system 12, a focus group 33, a zoom group 34, and a relay group 3
A zoom lens consisting of 5 is used. 36 is a position detection means (encoder or potentiometer) for detecting the position of the zoom section 34; 37.38 is a driving means (motor) for the lens 14 and the compensation means 9, which are part of the correction means;
It is. A zoom position signal from the position detection means 36 is sent to a magnification correction signal generation device 39. 39, a correction means is provided to mainly move the lens 14 to cancel the variation in lateral chromatic aberration as shown in FIG. 6 at each zoom position of the zoom group 34, and to prevent the image plane from shifting due to zooming. RO whose overall positional relationship of 9 is memorized in advance
M, and the drive means 3 according to the contents of this ROM.
At 7.38, a position control command is sent. By providing a similar mechanism for the red precedent, clear images without registration errors can be obtained over the entire zooming range of the projection optical system 12.

Furthermore, when focusing is performed, it is common in conventional zoom lenses that the lateral chromatic aberration fluctuation characteristics change as shown in FIG. This characteristic is also set in advance by R
If it is stored in the OM and the focus group 33 is equipped with a position detection means similar to the above-mentioned 36, the same operation as described above will be performed.
Clear images without registration errors can be obtained over the entire projection distance range.

Note that the above example aims to compensate for the high degree of registration error, but in the case of popular models, compensation is provided on one optical path that projects a color component image that has the largest size difference with respect to other color component images. Registration errors may be reduced by attaching one lens and changing the image size.

In the embodiments of the present invention described above, a liquid crystal panel is used as the image forming device 8, but the present invention is not necessarily limited to this, and a cathode ray tube may also be used.

As described above, in the projection device according to the present invention, the correction for the lateral chromatic aberration of the projection optical system remains weak, and
The projected images of the three colors of red light can be matched, and a projected image that is much clearer and of higher quality than before can be obtained.

In recent years, in the field of color display devices, there has been a growing trend for higher resolution and higher quality images to be required. Conventional projection display devices that use light bulbs have the advantages of being smaller, lighter, and lower cost than other methods that use cathode ray tubes, etc.1, but they are inferior in terms of resolution and image quality. . The present invention greatly improves this drawback, and can provide high-quality color images with a low-cost projection display device that has few restrictions on installation conditions, and has the effect of expanding the range of applications in the field of projection display devices. bring.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention. FIG. 2 is a block diagram of the correction means 9 used in the first embodiment of the present invention. FIG. 3 is a block diagram of the correction means 9 used in the second embodiment of the present invention. FIG. 4 is a block diagram of the correction means 9 used in the third embodiment of the present invention. FIG. 5 is a refractive index characteristic diagram of the element shown in FIG. 4. FIG. 6 is a graph showing the variation characteristics of chromatic aberration of magnification due to zooming of the projection optical system 12 used in FIG. FIG. 7 is a detailed view of portions 8, 9, 11, and 12 in FIG. 1 used in the fourth embodiment of the present invention. 2. FIG. 8, FIG. 9, and FIG. 10 are diagrams showing the conventional projection display system. 8...Light valve 9...Correction means 11...Color synthesis device 12...Projection optical system←(

Claims (3)

[Claims] (1) In a projection device that projects an image obtained by combining a plurality of images having different color components through a projection optical system, a correction means for optically correcting the size of at least one projected image is provided. A projection device comprising: (2) A projection device according to claim 1, comprising:
The projection apparatus is characterized in that the projection optical system is a zoom lens, and the correction means changes the size of the image according to the focal length of the zoom lens. (3) In a projection device having an image forming means for forming a plurality of images of different color components, a combining means for combining the images of the respective image forming means, and a projection optical system for projecting the combined image. , a variable magnification optical means disposed between at least one of the image forming means and the combining means, and a variable magnification ratio of the variable magnification optical means such that the image projected by the projection optical system substantially matches. A projection device characterized by comprising a control means for controlling.