JPS6246171Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a Schilleren optical system that performs monochrome display.

With the development of the information industry, large-screen projection displays have become important monitoring devices in fields such as education, industry, and the military. Projection type display monitor devices are becoming popular. Projection displays can be broadly divided into those that use a CRT (Cathode Ray Tube) to project and those that use a light bulb. In particular, the latter is capable of high-resolution, high-brightness displays, and includes methods such as the oil film method, photochromic method, methods using ferroelectric materials such as PLZT, and methods using light valves using photoconductors and elastomers or liquid crystals. , development is underway. When a phase change or a scattering effect is used for light valve display, a Schilleren optical system is used as the projection optical system. In recent years, there has been a demand for color monitors, and since the light valve system is monochromatic, coloring is done by inserting a color filter.

However, in light valves that use scattering effects, such as laser-written liquid crystal light valves, the display area written with laser light is scattered and becomes black, so when a color filter is inserted, coloring is limited to the background area. It is done. In this method, the background portion was displayed in only a single color, and it could hardly be called a color display. There is also a method of writing the background part by inverting the part to be written with a laser beam, but since the entire surface is scanned and recorded, the display speed is slow and the display is monochromatic on a black background.

An object of the present invention is to provide a monochrome display projection device that uses a light valve using a scattering effect and can display a monochrome display section on a white background.

The monocolor projection device of the present invention includes a light source, a condensing optical system that condenses light from the light source, and a first reflecting mirror installed near the light source image obtained by the condensing optical system. , a projection lens, a dielectric mirror that reflects part of the light from the projection lens and transmits part of it, a display device that is irradiated with the light transmitted by the dielectric mirror, and a display device that reflects the light reflected by the dielectric mirror. Second
, and is arranged such that the normal line of the first display surface and the light source of the projection lens form a small angle.

The present invention will be described in detail below with reference to the drawings. FIG. 1 shows an embodiment of a monochrome projection device according to the present invention. The white light 2 emitted from the light source 1 is again focused by the focusing optical system of the lens group 3. The collected white light is again converted into parallel light by the lens 5 and is incident on the dielectric mirror 6. If a dielectric mirror 6 that reflects blue and transmits yellow is used as the dielectric mirror 6, whose permittivity is shown in FIG. 2, the white light 2 in FIG.
It is divided into yellow light 10 which is transmitted through the light and blue light 11 which is reflected. The dielectric mirror has a multilayer structure consisting of alternating ZnS and MgF ₂ films, and by selecting the film thickness, it is possible to reflect light of any wavelength. The transmitted yellow light 10 enters the display device 7,
The reflected light modulated by the image displayed on the display device 7 passes through the dielectric mirror 6 and the lens 5 again and is focused. At this time, since the normal to the surface of the display device 7 and the optical axis of the lens 5 form a small angle (several degrees), the reflected light travels on a different optical path with a small angle from the incident optical path. The light is condensed by a first reflecting mirror 9 placed near the condensing point, reflected, and projected onto a screen. Also reflected blue light 11
enters a second reflecting mirror 8 disposed orthogonally to the display device 7, all of the blue light 11 is reflected, is reflected again by the dielectric mirror 6, and passes through the lens 5.
Similar to the yellow light 10, it is focused and reflected by the reflecting mirror 9 and projected onto the screen.

Among the light valves already described as the display device 7, the relationship between display colors will be explained using a scattering type light valve using liquid crystal as an example. The image display portion of the display device 7 scatters the incident yellow light 10, and the scattered light from this portion is not condensed into the reflected light 9 and is therefore not projected onto the screen. In other words, a black image with a yellow background is formed on the display device 7. Blue light is projected onto the screen from the reflecting mirror 8 over the entire surface. By combining these projected lights, the blue light overlaps the image portion displayed on the display device 7, resulting in a blue image. Further, the background portion of the display device 7 becomes white due to the overlap of the yellow light and the blue light. That is, a blue image is displayed on white. In this way, a monochrome image that appears on a white background due to the reflection characteristics of the dielectric mirror can be displayed. Therefore, by selecting a dielectric mirror, it is possible to project an image in any color such as green or red.

As described in detail above, according to the present invention, a projection device that displays a simple monochrome image using a dielectric mirror can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a projection device according to the present invention. FIG. 2 is a diagram illustrating the characteristics of the dielectric mirror used in the present invention. In the figure, 1 is a light source, 2 is white light, 3 and 5 are lenses, 6 is a dielectric mirror, 7 is a display device, 8,
9 is a reflecting mirror.

Claims (1)

[Scope of utility model registration request] A light source, a condensing optical system that condenses light from the light source, a first reflecting mirror installed near the light source image obtained by the condensing optical system, a projection lens, and a condensing optical system that condenses light from the light source. A dielectric mirror that reflects part of the light and transmits part of the light, a display device that is irradiated with the light transmitted by the dielectric mirror, and a second reflecting mirror that reflects the light reflected by the dielectric mirror, A monochrome projection device characterized in that the normal line of the first display device surface and the optical axis of the projection lens are arranged so as to form a small angle.