Projection display device

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to a projection type display device that displays a video image, a computer image, or the like.

【0002】

[Conventional technology]

Recently, a magnifying projection method using a liquid crystal or the like to magnify and project an image displayed on the screen to display it as a large screen has been attracting attention.

【0003】

In a conventional projection display device using this type of light bulb, as shown in FIG. 14, the transmissive liquid crystal panel is illuminated by a light source, and the image displayed on the liquid crystal panel is magnified by a projection lens. It is a structure that leads to the screen.

【0004】

However, in the above-mentioned projection type display device, when the device is installed on the floor or ceiling and an attempt is made to project it on a screen installed on a wall surface, the projected light emitted from the projection lens is oblique to the screen, so that the projected image is displayed. It will be distorted into a trapezoidal shape.

【0005】

Therefore, a shift optical system can be considered as a means for solving this problem. As shown in Fig. 15, this is a light bulb and screen shifted up and down. This keeps the light bulb and screen parallel so that trapezoidal distortion does not occur. However, this projection type display device requires a projection lens having a large angle of view, and has a problem that the angle at which the projected light is obliquely incident on the screen is also small and limited.

【0006】

[Problems to be Solved by the Invention]

In order to solve such a problem, the present inventors are a projection optical device having a light source, an optical modulation means, and a projection means for obliquely projecting an image generated by the optical modulation means on a screen. The means are a first projection optical means that converts the image generated by the optical modulation means into an intermediate image with trapezoidal distortion, and a second means that converts the intermediate image with trapezoidal distortion into an image without trapezoidal distortion on the screen. We are proposing a projection optical device consisting of projection optical means (Japanese Patent Application No. 2-224823).

【0007】

According to our proposal described above, it has become possible to obtain a projection display device that can obtain a projection image without trapezoidal distortion even when projected obliquely on a screen. However, an object of the present invention is to reduce the distance between the projection means and the screen. It is an object of the present invention to provide a projection type display device that is in focus even when the enlargement ratio is changed and that trapezoidal distortion does not occur in the projected image.

【0008】

[Means for solving problems]

In order to achieve the above object, the projection type display device of the present invention includes a light source, an optical modulation means, and a projection means for obliquely projecting an image generated by the optical modulation means on a screen. The means are a first projection optical means that converts the image generated by the optical modulation means into an intermediate image with trapezoidal distortion, and a second means that converts the intermediate image with trapezoidal distortion into an image without trapezoidal distortion on the screen. It is composed of a projection optical means.

【0009】

Then, the normals of the light modulation means surface, the intermediate image surface, and the screen surface at the positions where they intersect with the main rays are arranged so that the optical axes of the first and second projection means are in the same plane C.

【0010】

Further, the point g where the line group parallel to the C plane on the optical modulation means surface intersects on the intermediate image plane by the first projection optical means and the line group parallel to the C plane on the screen surface are the second. It is arranged so that it coincides with the point g'that intersects on the intermediate image plane by the projection optical means.

【0011】

Then, in order to keep the projection image in focus and prevent trapezoidal distortion from occurring even if the distance between the projection means and the screen changes and the magnification changes, the first or second projection optical means is used. , Links or cams or gears allow rotation around point g.

【0012】

[Example]

(Example 1) FIG. 1 shows a projection type display device according to the present invention, FIGS. 2, 3 and 4 are diagrams for explaining the optical arrangement of the embodiment of FIG. 1, and FIG. 5 is a light. The image of the bulb is shown, FIG. 6 shows an intermediate image with trapezoidal distortion, and FIG. 7 shows an image on the screen without trapezoidal distortion.

【0013】

In FIGS. 1, 2, 3, and 4, the optical axis of the first lens 3 of the first projection optical system, the optical axis of the second lens 4, the optical axis of the second projection optical system 6, and the main ray. The normal lines of the light valve 2 and the screen 7 at the intersection are in the same plane.

【0014】

As shown in FIG. 2, the first lens 3 and the second lens 4 of the first projection optical system are tilted by an angle δ with respect to each other, and the image side focusing plane of the first lens 3 and the object side focusing plane of the second lens 4 Arrange so that the intersection line passes almost on the main ray. Further, as shown in FIG. 3, the intermediate image 5, the second projection optical system 6, and the screen 7 are arranged so that their extension surfaces intersect on the same straight line.

【0015】

In FIG. 1, the light emitted from the light source 1 illuminates the light bulb 2 almost in parallel. Therefore, the light rays enter the light bulb at almost the same angle of incidence, and uniform brightness and contrast can be obtained on the entire surface of the light bulb 2.

【0016】

The image of the square light bulb 2 as shown in FIG. 5 is formed into a trapezoidal intermediate image 5 as shown in FIG. 6 by the first lens 3 and the second lens 4 of the first projection optical system tilted from each other. To do. As shown in FIG. 2, g is the line of intersection between the plane parallel to the main ray, including the line of intersection of the image-side focusing plane of the first lens 3 and the main plane of the second lens 4, and the plane with the intermediate image 5. To do. Let g ́ be the line of intersection between the object-side focal plane of the second projection optical system 6 and the plane on which the intermediate image 5 is located. When g and g ́ are matched as shown in FIG. 2, the trapezoidal distorted intermediate image 5 as shown in FIG. 6 is screened as an image without trapezoidal distortion as shown in FIG. 7 by the second projection optical system 6. Image on 7.

【0017】

The first lens 3 and the second lens 4 of the first projection optical system are configured by a combination lens tilted as shown in FIG. 8, and aberration can be corrected.

【0018】

Here, as shown in FIG. 4, when the screen 7 approaches the second projection optical system 6, the intermediate field for obtaining a projection image without trapezoidal distortion is rotated around g (g ́). It will be arranged like this.

【0019】

Therefore, as shown in FIG. 1, if the first projection optical systems 3 and 4 are rotated by the link 8 with the g point as a fulcrum, the distance between the projection means and the screen 7 changes, and the enlargement ratio changes. However, it is possible to obtain a projected image that is in focus and has no trapezoidal distortion.

【0020】

(Example 2) FIG. 9 is a diagram of a projection type display device according to a second embodiment of the present invention.

【0021】

Similar to the first embodiment, the distance of the screen 7 is changed and enlarged by rotating the first projection optical systems 3 and 4 by the cam 9 so as to move around the g point in FIG. Even if the rate changes, it is possible to obtain a projected image that is in focus and has no trapezoidal distortion.

【0022】

(Example 3) FIG. 10 is a diagram of a projection type display device according to a third embodiment of the present invention.

【0023】

Similar to the first embodiment, by rotating the second projection optical system 6 by the link 8 so as to move around the g point in FIG. 1, the distance of the screen 7 is changed and the enlargement ratio is increased. Even if it changes, it is possible to obtain a projected image that is in focus and has no trapezoidal distortion.

【0024】

(Example 4) FIG. 11 is a diagram of a projection type display device according to a fourth embodiment of the present invention.

【0025】

Similar to the first embodiment, the distance of the screen 7 is changed by rotating the second projection optical system 6 by the cam 9 so as to move around the g point in FIG. 1, and the enlargement ratio is increased. Even if it changes, it is possible to obtain a projected image that is in focus and has no trapezoidal distortion.

【0026】

(Example 5) FIG. 12 is a diagram of a projection type display device according to a fifth embodiment of the present invention, and FIG. 13 is a diagram for explaining an embodiment of FIG.

【0027】

As shown in FIG. 13, the gear 10a and the second projection optical system 6 and the gear 10b and the gear 10c are arranged coaxially, and the gear 10b rotates at the same time as the gear 10c rotates, and the gear 10a rotates by the gear 10b. To do so. Further, the second projection optical system 6 is fixed to the gear 10a, and the second projection optical system 6 is arranged so that the center thereof is at the position h from the g point in FIG. If the radius R of the gear 10c is set to R = r1 / r2 * h, the second projection optical system 6 is almost equivalent to rotating around the g point. Therefore, as in the first embodiment, even if the distance of the screen 7 changes and the enlargement ratio changes, it is possible to obtain a projected image that is in focus and has no trapezoidal distortion.

【0028】

[Effect of the invention]

As described above, by rotating the first or second projection optical means by a link, a cam, or a gear, the distance between the projection means and the screen changes, and even if the magnification changes, the focus is achieved. Moreover, it is possible to provide a projection type display device that does not cause trapezoidal distortion in the projected image.

[Simple explanation of drawings]

[Figure 1]

It is a figure of the projection type display device by 1st Example of this invention.

[Figure 2]

It is explanatory drawing of the condition that trapezoidal distortion does not occur in the projection type display device by this invention.

[Fig. 3]

It is explanatory drawing of the image formation of the projection type display device by this invention.

[Fig. 4]

It is explanatory drawing when the distance of a screen is changed.

[Fig. 5]

It is explanatory drawing of the display image of the light bulb of FIG.

[Fig. 6]

It is explanatory drawing of the intermediate image of FIG.

[Fig. 7]

It is explanatory drawing of the image formation on the screen of FIG.

[Fig. 8]

It is sectional drawing of the Example of the lens used in this invention.

[Fig. 9]

It is a figure of the projection type display device by 2nd Example of this invention.

[Fig. 10]

It is a figure of the projection type display device by the 3rd Example of this invention.

[Fig. 11]

It is a figure of the projection type display device according to 4th Example of this invention.

[Fig. 12]

It is a figure of the projection type display device according to 5th Example of this invention.

[Fig. 13]

It is explanatory drawing of the 5th Example of this invention.

[Fig. 14]

It is a figure of the conventional projection type display device.

[Fig. 15]

It is a figure of the conventional shift type projection type display device.

[Explanation of symbols]

1 light source 2 light bulb 3 First lens of the first projection optical system 4 Second lens of the first projection optical system 5 Intermediate image 6 Second projection optical system 7 screen 8 links 9 cam 10a, 10b, 10c gears 11 Projection lens