CN1069982C - Virtual image display system for reducing peripheral reflection and low radiation - Google Patents

Abstract

A virtual image display system with reduced ambient reflection and low emissivity comprising a black and white image source for projecting a black and white image which is then projected to a magnifying virtual image optical device comprising a concave mirror, the device and a color light valve (comprising A linear polarizer) receives a black-and-white image to produce a magnified color virtual image. The invention also includes a quarter-wave plate that is used with the color light valve (including the linear polarizer) to reduce the surrounding reflections.

Description

Virtual image display system with reduced ambient reflection and low radiation

A virtual image display system for reducing ambient reflection and low radiation, belonging to devices or devices for controlling the intensity, color, phase, polarization or squareness of light.

In modern color display systems, there is an urgent need for large-scale color image display devices with high-intensity and bright colors, and this system often suffers from a concern, that is, high-intensity and bright images require high-power input, resulting in High power consumption and high radiation levels are harmful to the health of long-term users at close range, and the application is limited; in addition, "ghost images" caused by surrounding reflections (often generated from self-reflection) may interfere and negatively affect The visual effect of this display system; in order to reduce the surrounding reflection, one of the traditional technologies is to reduce the surrounding light reflection by means of a circular polarizer, US Patent 4657348 "eliminates the reflection device from the liquid crystal display", discloses an optical device , which can eliminate the reflection from the LCD, but this technology still has some limitations for modern display components, especially for the virtual image color display system, because it also reduces the brightness of the image display; in addition, for computers and office equipment Virtual image display screens used together typically have strong overhead lighting that casts strong ambient light onto the window screen. Ambient reflections of this overhead lighting interfere with the displayed virtual image and can become very disturbing; another U.S. Patent 5278532 "Virtual Image Display for Automatic Devices" discloses a virtual image automatic display system, which uses a special cover design to prevent strong reflection of surrounding light; the large-size virtual image display system is a large-size TV or computer screen display system and an automatic device The display system is different. This virtual image display system is more susceptible to the influence of the surrounding reflection. The surrounding reflection is caused by the larger size of the window screen and the overhead lighting projected to the screen and then to the window. In addition, the cover design is suitable for the application of automation devices. Might work, but not suitable for modern larger monitors.

The purpose of the present invention is to design an optical system that provides a high-quality virtual image display system and can reduce the surrounding reflection without excessively reducing the brightness of the image display, and can reduce the reflection of the overhead lighting device, which can display large-size color images and There is no need to use high-power and high-radiation image sources.

The solution of the present invention includes a monochrome image source for projecting a black and white image, a color light valve in front of the monochrome image source for converting the black and white image into a color image, a beam splitter reflecting the color image to a concave mirror, The concave mirror magnifies the received color image into a color virtual image. There is a circular polarizer in front of the concave mirror, which includes a quarter-wavelength plate and a linear polarizer. There is a circular polarizer in front of the circular polarizer. Window, circular polarizer to pass color image and reduce reflection around concave mirror, beam splitter and concave mirror are arranged in an off-axis manner so that reflection axis of beam mirror is relative to incident and reflected light path of monochrome image It is axisymmetric, wherein the reflective axis is deviated from the concave mirror by an angle of 10 degrees or less, so that the surrounding reflection and overhead can be reduced by using a low-power monochromatic image source and the above-mentioned optical system design. Light reflection and reduce the impact of high-power radiation on human health.

The advantages of the present invention are: provide a high-quality virtual image display system and can reduce reflections caused by surrounding reflections and overhead lighting devices without excessively reducing the brightness of image display. In addition, the present invention can display large-scale high-brightness color images It is not necessary to use high-power and high-radiation image sources.

The present invention has following accompanying drawing:

Accompanying drawing 1 is the optical system diagram of the present invention.

Accompanying drawing 2 is another optical system diagram of the present invention.

Describe embodiments of the present invention below in conjunction with accompanying drawing:

Fig. 1 is a system diagram of a virtual image display system 100 of the present invention, in which a low-power black and white image source 105 is arranged, which can be a cathode ray tube (CRT), a liquid display (LCD), a field effect injection element, a deformable mirror element or For other forms of electro-optic image elements, the image source 105 emits a black and white image and projects it to a color light valve 110 and converts the black and white image into a color image. The color light valve can be a liquid crystal color light valve as described in US Patent No. Parts and color polarizers, others such as ferroelectric electronic light valves (including ferroelectric parts and color polarizers) can also be used as color light valves, these two light valves are composed of electro-optic materials and polarizers , the image light becomes linearly polarized light after passing through the light valve 110, and the quarter-wavelength plate 115 is used in combination with the color light valve 110 to form a circularly polarized image so that the linearly polarized light passes through the light valve 110 After passing through the quarter-wave plate 115, the beam 118 is converted into a specific polarization direction. The polarized beam 118 is then reflected from the beam splitter 120 and projected to the concave mirror 125, and then the beam is reflected from the concave mirror. And pass through a circular polarizer 128, this circular polarizer comprises the second 1/4 long plate 130 and a linear polarizer 135, then the light beam that passes through the circular polarizer reaches the visual window 140 The beam splitter 120 and the concave reflector 125 are arranged in an off-axis type, so that the reflection axis of the beam reflector is axisymmetric for the incident and reflected light paths of the monochromatic image, so that the reflection axis is for the processed The image light beam 118 deviates from the optical axis, and the reflection axis 150 is about 10 degrees or less than the optical axis 160 of the concave reflector 125; the light output from the image source 105 passes through the liquid crystal color light valve (LCCS) 110 and the quadrant After one of the wavelength plates 115, it becomes circularly polarized light. After the circularly polarized beam 118 is reflected by the beam splitter 120 and the concave mirror 125, the direction of the circular polarization remains unchanged, but the image is enlarged into a color image , when the circular polarizer 128 is designed to be consistent with the polarization direction of the circularly polarized beam 118 reflected from the concave mirror 125, there will not be too much polarization after the beam passes through the circular polarizer 128 Attenuation; however, the external ambient light 170 becomes circularly polarized after passing through the circular polarizer 128, and when the ambient reflected light 170 is reflected back from the concave reflector 125, the circular polarization direction of the reflected ambient light 170 is thus Change, in this display system 100, the ambient reflection light 170 that reflects back is blocked by the circular polarizer 128, and this peripheral reflection often interferes with the virtual image 180 displayed behind the concave mirror 125, but is blocked by the circular polarizer , so that the surrounding reflection is greatly reduced; when the optical path of the image reflection, the reflection of the circularly polarized beam 118 is arranged on the optical axis, the overhead illumination light will often cause high-intensity reflected light back to the viewer's eyes, through the subtle Adjusting the reflector 125 so that it deviates slightly from the optical axis of the image reflection, the surrounding reflection of the overhead light can be reduced directly from the viewing window 140, so that it does not directly reach the viewer's eyes, thereby reducing the reflection from the overhead lighting. At the same time, because the circular polarizer 128 is in the right-hand circular polarization direction, its blocking effect and the off-axis design can further reduce the interference reflected from the surrounding; therefore, the circular polarizer 128 is used in combination The virtual image display system 110 configured in an off-axis configuration can considerably reduce peripheral reflections and reflections caused by overhead light, and the display image provided to the viewer has a very low degree of interference compared with traditional images. On the other hand, , using the low-power radiation image source 105 can obtain excellent and bright images, and because the circular polarizer 128 is used before the black-and-white image source 106, a color light valve and a quarter-wavelength plate 115 are used to make the image There is no serious loss of brightness.

2 is a system diagram of a virtual image display system 200 according to another embodiment of the present invention. This virtual image display system 200 receives an image from a monochrome image source 205 and displays it. The image beam 210 is projected to a beam splitter 215, and the The beam splitter 215 thus reflects the image onto the concave mirror 220, which reflects the light beam 210 onto a window assembly comprising a quarter wave plate 225 and a color light valve 235, and The color light valve 235 includes a linearly polarized polarizer 230 facing the quarter-wave plate 225. The color light valve 235 converts the image beam 210 into For color images, when the viewer looks inside the window 240, he will see the color virtual image 250 behind the concave mirror 220; for this type of display system 200, when the ambient light 260 enters the system, the ambient light 260 passes through After the light valve, its intensity is reduced to about 6% of the original intensity, and the ambient light is converted into a circle by the action of the quarter wave plate 225 and the linear polarization plate 230 located inside the color light valve assembly 235. polarized light; for the ambient reflected light 260 reflected back from the concave reflector 220, the direction of this circular polarization is changed, and then passed through the quarter wave plate 225 and the polarizer 230 in the system 200 The effect of blocking the surrounding reflected light 260; because the color light valve 235 in the window assembly will cause an attenuation factor, the residual surrounding reflection of the virtual image display system can be further reduced, so by the circular polarizer of the window assembly ( Including the quarter-wave plate 225 and the linear polarizer 230) and the absorption characteristics of the color light valve assembly 235, the surrounding reflection can be reduced overall; in addition, because the system 100 uses two polarizers, the The system 200 only uses one polarizer 230, so the display system 200 can obtain higher brightness improvement; the arrangement of the beam splitter 215 and the concave mirror 220 is similar to the design of FIG. 1, that is, for the image For the light beam 250, the optical axis of the image reflection is slightly offset from the optical axis 270 of the concave mirror 220, and the viewer is less likely to be affected by the overhead illumination light because these light reflections are directly from the image reflection with only a slight drop. Reflection interference; the color light valve in system 200 is the same as that in system 100; the concave reflectors of system 100 and system 200 can be spherical mirror or aspheric mirror shape, using spherical mirror can improve some optical characteristics, such as system imbalance or distortion question.

Claims (3)

1, the virtual image display system of a kind of minimizing peripheral reflection and low radiation, it is characterized in that, in monochromatic image source (a 105) front one colored light valve (110) is arranged, in this colour light valve (110) front one quarter wave plate (115) is arranged, after monochromatic image source (105) passes through colored light valve (110) and quarter wave plate (115), make image form the folded light beam (118) of round polar biased chromatic image, this folded light beam (118) is projected to concave mirror (125) back and forms the virtual image of amplifying, be provided with second quarter wave plate (130) and linear polarizer (135) in concave mirror (125) front and constitute circle polarization device (128), at circle polarization device (128), quarter wave plate (115) and colored light valve (110) front are observing window (140), beam splitter (120) and concave mirror (125) are arranged in the off-axis mode, make the axis of reflection of beam reflection mirror, incident and reflected light path for described monochromatic image are a rotational symmetry, and wherein said axis of reflection system departs from 10 degree or low-angle more from described concave mirror.

2, by the described display system of claim 1, it is characterized in that colored light valve is colored light valve of liquid crystal or the colored light valve of ferroelectricity, the former comprises liquid crystal display cells and colored polarizer, the latter comprises ferroelectricity element and colored polarizer.

3, the virtual image display system of a kind of minimizing peripheral reflection and low radiation, it is characterized in that, monochromatic image source (205) front of this system is beam splitter (215), on the window assembly of concave mirror (220) front, be provided with a quarter wave plate (225) and a colored light valve (235), this colour light valve comprises a linear polar biased polarizer (230).

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