JPS6128176Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a Schilleren optical system that performs high-intensity projection.

With the development of the information industry, large-screen, high-brightness projection displays are becoming important in fields such as educational, industrial, and military applications. Projection displays can be broadly divided into those that project a CRT (Catnode Ray Tube) and those that use a light bulb. In particular, the latter is capable of high-resolution and high-brightness displays, and research includes methods using oil film methods, photochromic methods, methods using ferroelectric materials such as PLZT, and methods using light valves using photoconductors and elastomers or liquid crystals. , development is underway. A Schilleren optical system is usually used for projection of the light valve, and a xenon lamp is used as the light source. However, the light source of the Schilleren optical system usually needs to be a point light source with good coherence, and spatial uniformity of the light amount distribution is also required, and the xenon lamp is insufficient in this respect. In particular, a horizontal xenon lamp that projects a large amount of light has a donut-shaped light amount distribution at the output end because it uses a perforated mirror. For this purpose, conventionally, as shown in FIG. The image is focused upwards, providing almost uniform illumination light. The input image 5 is projected through a lens 6 and a Schiller lens stop 8 to form an enlarged image 7.
As the diameter of the pinhole 3 is made smaller, a more uniform light amount distribution can be obtained, but the intensity of the illumination light on the input image 5 becomes weaker. Furthermore, because of the imaging system, the light flux that enters the input image 5 is not parallel light, and the light flux that has passed through the input image 5 cannot be sufficiently focused by the lens 6. For this reason, the Schiller lens stop 8 does not work effectively and cannot project an image with sufficient contrast when the input image is a scatterer.

The purpose of the present invention is to realize a Schilleren projection device using a horizontal xenon lamp that can project parallel light with a uniform light intensity distribution onto an input image.

According to this invention, in a projection device composed of a xenon lamp, a perforated ellipsoidal mirror, a lens, and a light-shielding mask, a first ellipsoidal mirror and a light spot focused by the ellipsoidal mirror are imaged. a lens, and a second lens that re-images the image of the ellipsoidal mirror near the rear convergence point.
and a third lens placed behind the second lens so as to reimage the light spot on the input image plane and obtain a uniform parallel light beam. A device is obtained.

Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 2 shows a first embodiment of the present invention. Light emitted from the xenon lamp 1 is focused at point B by the ellipsoidal mirror 2. The light flux is ellipsoidal mirror 2
It has a donut shape due to hole A, but B
At a point, the light is focused into an intensity distribution shape that is approximately normal. The first lens 10 is arranged so as to form an image of the hole A in the vicinity a of the rear focal point, and to form an image of point B at a position b seven minutes away from the image of A. At this time, the light quantity distribution of line A' at point a is doughnut-shaped as shown in figure a, and the light quantity distribution of image B' at point b is almost uniform as shown in figure b. The light beam is then condensed by the second lens 11, expanded again by the third lens 12, and irradiated onto the input image plane 5. At this time, if the focal lengths of lenses 11 and 12 are the same f, then the distance between B' and lens 11 is f,
The distance between the lens 11 and the lens 12 is set to 2f, and the distance between the lens 12 and the input image plane 5 is set to f. At this time, the image B' is telecentrically formed as an image B'' on the input image plane 5, and a uniform light amount distribution is obtained.
Further, image A' is formed near the rear focal point of lens 11 as image A', and its size is reduced in two steps by lens 10 and lens 11. Therefore, since the image A'' can be made small, the light beam incident on the input image plane 5 can have fairly good parallelism.The light beam reflected from the input image 5 is reflected by the lens 12.
The light is focused again by the Schiller lens stop and reflected by the mirror 8, and a projected image 7 with good contrast is obtained.

FIG. 3 shows a second embodiment of the present invention. This is the same as FIG. 2 except that a concave lens 101 is used instead of the first lens 10. The advantage is that the length of the optical system can be reduced compared to the optical system of FIG. Although a reflective input image has been described as an example, similar effects can be obtained with an optical system for a transmissive input image.

As described in detail above, according to the present invention, a high-intensity Schilleren projection device with good contrast using a horizontal xenon lamp can be obtained.

[Brief explanation of drawings]

FIG. 1 shows a conventional projection device using a xenon lamp, FIG. 2 shows a first embodiment of the present invention, and FIG. 3 shows a second embodiment of the present invention. In the figure, 1 is a xenon lamp, 2 is an ellipsoidal mirror, 8 is a Schiller lens stop and mirror, 10,
11, 12, and 101 are lenses.

Claims (1)

[Claims for Utility Model Registration] In a projection device composed of a xenon lamp, a perforated ellipsoidal mirror, a lens, and a Schiller lens stop, the ellipsoidal mirror connects the light point condensed by the ellipsoidal mirror. a first lens for imaging; a second lens for re-imaging the image of the ellipsoidal mirror near the rear focal point; a Schiller lens stop placed near the rear focal point; and a Schiller lens stop placed near the rear focal point; and a third lens placed behind the second lens so as to enlarge and reimage the image on an input image plane to obtain a uniform parallel light beam.