CN1900762A - Projector with shading device and method for eliminating stray light - Google Patents

Abstract

A projector with micro-lens unit is composed of an illuminating system, a digital micro-lens unit under the illumination of said illuminating system, and a lens for receiving the light reflected by said digital micro-lens unit and focusing it for imaging. Wherein a light shielding device is further disposed between the illumination system and the digital micro-mirror device for shielding stray light generated by the illumination system.

Description

Projector with shading device and method for eliminating stray light

【Technical field】

The present invention relates to a projector, especially a projector using a digital micromirror device (DMD) and avoiding stray light interference.

【Prior technology】

The working principle of a projector using a digital micromirror device (DMD, digital micromirror device) is that the digital micromirror device has a plurality of miniature mirrors as optical switches to receive electronic signals, such as characters of digital electronic signals, by changing The output of light characters is generated by the tilt angle of the micromirror. Each micro-mirror can reflect the light in two angles. With the light source and a lens for projection imaging, when the micro-mirror is in the "open" (conduction, on) state, it will turn to an angle to illuminate the light source. The incoming light is reflected into the lens to form an image on a screen; when the micro-mirror is in the "off" (non-conductive, off) state, it turns to another angle to reflect the light to other places. At this time, the screen is relatively The location of the micromirrors then appears rather dark. The digital micromirror device receives electronic characters and transmits optical characters. This technology is called binary pulse width modulation (BWM), and the details are not the focus of the present invention so will not be repeated.

Please refer to FIG. 2 , which is a schematic diagram of the internal structure of a conventional digital micromirror device (DMD) projector. Wherein the light source 10 provides the digital micromirror device 2 light sources, and in the middle, the light is concentrated and projected onto the digital micromirror device 2 as uniformly as possible by the condenser lens 12, and the received light is added to the digital micromirror device 2 After processing, the light is reflected to the lens 5, and is imaged by the lens 5 onto a screen (not shown in the figure) to generate an effective image area 41'. The shape of the projection area is circular, so the digital micromirror device 2 can be regarded as the inscribed quadrilateral of the projection area of the condenser 12, and therefore the projection area must have a part of the area beyond the digital micromirror device 2, which is in the digital micromirror device. 2, the stray light area 45 formed around the micromirror device 2 is regarded as the effective illumination area 41 as the area that does not exceed but just projects on the micromirror device 2, and also covers the digital micromirror with respect to the lens 5 with an image circle. device 2, so it will also exceed the range of the digital micromirror device 2, and project the reflected light of the stray light area 45 onto the screen together to form a stray image area 45', so that the viewer can see images outside the effective image area 41', It is a distraction for the viewer.

In order to solve the trouble caused by this stray light 45, there are several ways, one of which is to perform matting treatment on the surrounding parts of the digital micromirror device 2, and reduce the strong reflection by increasing the roughness of the surface, but it cannot completely eliminate the reflection , it just makes the surroundings of the digital micromirror device 2 look darker; another way is to isolate the light in the form of a baffle around the digital micromirror device 2, although it avoids other surroundings of the digital micromirror device 2. reflection of electronic components, but still cannot completely eliminate the reflection, because the stray light is still projected around the digital micromirror device 2; there is another way to directly shape the light projected by the lighting system 100 into a square shape, however, the lighting system 100 The light needs to pass through one or more mirrors to irradiate the light on the digital micromirror device 2, so after being reflected by the mirrors, the shape of the projected area of the light is often not as expected.

Please refer to FIG. 1 , which is a schematic diagram of a three-dimensional structure of an existing projector without a shading device, wherein the projector 1 includes an illumination system 100 for providing a light source for the projector, and therefore further includes a light source 10 for generating the first A ray 10', in front of the light source 10, a condenser lens 12 is arranged, usually a combination of lenses, and the first ray 10' is directed to the condensor 12, and the condensor 12 condenses the first ray 10' to become A second light ray 12' is projected to a reflector group 14, usually the reflector group 14 is made up of one or more reflectors, in terms of the present invention, the reflector group 14 can be divided into a first reflector 141 and the second reflector 142, wherein the first reflector 141 is irradiated by the second light 12', and reflects a third light 141' to the second reflector 142, and the second reflector 142 reflects a fourth The light 142', the fourth light 142' shoots towards a digital micromirror device 2 (DMD, digital micromirrodevice), and the digital micromirror device 2 changes the micromirror therein according to the electronic signal received by itself (Fig. (not shown in the figure), then the fourth light 142' is reflected to become the image beam 20' and captured by the lens 5 to become a projected light beam 50', and finally, a projected image is formed on a screen (not shown in the figure) Zone 4'.

Wherein, the reason why will utilize reflecting mirror group 14 is that this digital micromirror device 2 needs the irradiation of light source, and the angle of incidence of this light source should not be too large, so need utilize reflecting mirror group 14 to be made the side surface of digital micromirror device 2 The projected light is adjusted to an appropriate angle to enter the digital micromirror device 2 . Moreover, the reason why the lighting system 100 forms a large angle with the digital micromirror device 2 is that the lighting system 100 has a certain volume. If it is necessary to form a small angle with the digital micromirror device 2, it will inevitably affect the lens 5. configuration, that is to say, there will be a situation where the lighting system 100 is next to the lens 5, so that the two are restrained from each other, and because the lens must be almost directly facing the digital micromirror device 2, so for example, if the lighting system 100 is to have If the illumination intensity is sufficient, the volume of the light source 10 and the condenser lens 12 will inevitably increase, which will take up the space of the lens 5, so that the lens with zoom and shift function cannot be applied, because the lens with zoom or shift function The lens volume is usually larger, that is, the diameter is larger and the length is longer. Conversely, if a lens with a zoom or shift function is used, the space of the lighting system 100 will be occupied, so the lighting system 100 Moved to a place on the side to avoid mutual interference away from the lens 5, the new problem produced is that the angle between the optical axis of the illumination system 100 and the digital micromirror device 2 is too large, in order to achieve the effect of reducing the angle as much as possible, so The reflection mirror group 14 is utilized to change the angle of the light from the illumination system 100 to facilitate the illumination of the digital micromirror device 2. Therefore, the fourth light ray 142' The angle of illumination onto the DMD 2 is minimized as much as possible.

However, although the first reflector 141 and the second reflector 142 can be used to make the intensity of illumination received by each individual micromirror of the digital micromirror device 2 approach the same, but because the first reflector 141 and the second reflector 142 is to reflect the deflection angle of the light, so the shape of the area projected by the second light 12' has changed. Therefore, after being reflected by the first reflector 141 and the second reflector 142, the fourth light The shape of the projection area 4 of 142' is quite different from the shape of the projection area of the second light 12'. Please continue to refer to FIG. An effective lighting area 41 and a distorted light area 43, and the so-called effective lighting area means that its lighting area is effectively covered on the digital micromirror device 2, and the so-called distorted light area 43 is to irradiate the digital micromirror device 2, and because the lens 5 usually has the function of zooming or shifting, the image circle that can be imaged is relatively large. Captured by the lens 5 and projected out, a projected image area 4' is formed. At this time, the effective image area 41' corresponds to the range of the effective illumination area 41, and the distorted image area 43' corresponds to the area of the distorted light area 43. scope.

Compared with the prior art of FIG. 2, although the distorted light area 43 produced by the prior art of FIG. 1 is much smaller than the stray light area 45 of FIG. 2, and the distorted image area 43' is sometimes not projected on a screen , but it will still be imaged around the screen, and may be caught in the audience's sight, so it is a kind of disturbance to the audience.

Therefore, in the field of projectors, there is a great need for a projector that effectively avoids stray light interference and allows users to use it easily.

【Content of invention】

In order to achieve the above object, the present invention provides a projector with a shading device, including an illumination system for providing a light source for the projector, which further includes a light source for generating light, and a condenser lens for converging the light, And a primary reflector to reflect the light. The projector also includes a digital micromirror device (DMD), which is used to receive the light reflected by the main reflector and reflect it after being processed, and a lens, which is used to receive the light processed and reflected by the digital micromirror device , the lens focuses the light into an image; and a light-shielding device is arranged between the digital micromirror device and the lighting system to shield the stray light generated by the lighting system.

As in the above-mentioned projector, wherein the reflecting mirror produces a projection area when reflecting the light, including an effective illumination area and a distorted light area, wherein the effective illumination area covers the digital micromirror device, and the distorted light area is The stray light is formed around the effective lighting area, and a projected light path is formed between the projection area and the reflector, including an effective illumination formed between the effective lighting area and the reflector. A light path, and a distorted light path formed between the distorted light area and the reflector, and the shading device is used to block the distorted light path.

As in the projector above, wherein the reflector further includes a first reflector for changing the direction of the light; and a second reflector for receiving the light reflected by the first reflector, and The light is reflected to the DMD.

As in the above projector, wherein the shading device is subjected to matting treatment.

As in the above projector, wherein the matting treatment is selected from matting paint and flocking.

To achieve the above object, the present invention provides a method for eliminating stray light applied to a projector, comprising the following steps: (1) providing an illumination system for providing a light source for the projector; (2) providing a digital micromirror device , for processing and reflecting light from the lighting system; (3) generating a projected light path between the lighting system and the digital micromirror device; (4) providing a shading device between the lighting system and the digital micromirror between the devices; and (5) providing a lens for receiving the light reflected by the digital micromirror device and forming an image, wherein the shading device blocks a part of the projection light path to avoid the part The light is projected to the periphery of the digital micromirror device.

In the above-mentioned method, wherein the projected light path can be further divided into an effective projected light path and a distorted light path, and the part blocked by the shading device is the distorted light path.

To achieve the above object, the present invention also provides a micromirror device projector, comprising an illumination system, a digital micromirror device illuminated by the illumination system, a lens receiving light reflected by the digital micromirror device, and The light is focused and imaged, and the projector is characterized in that a light-shielding device is set between the lighting system and the digital micro-mirror device to block a stray light generated by the lighting system. In the above-mentioned projector, an effective illumination light path is further formed between the illumination system and the digital micromirror device, and a distorted light path is formed around the effective illumination light path, wherein the shading device is located on the distorted light path , so that the distorted light path does not reach the digital micromirror device.

The above-mentioned projector, wherein the shading device is a baffle, which directly blocks the light on the distorted light path.

【Description of drawings】

FIG. 1 is a schematic diagram of a three-dimensional structure of an existing projector without a shading device;

Fig. 2 is the internal structure schematic diagram of existing micromirror device (MD) projector;

FIG. 3 is a schematic diagram of a three-dimensional structure of a projector with a shading device of the present invention; and

FIG. 4 is a three-dimensional schematic view of the optical path generated between the second reflector and the micromirror device of the present invention.

【Detailed ways】

Please refer to FIG. 3 , which is a three-dimensional structural schematic view of a projector with a shading device according to the present invention. Wherein the projector 1' includes an illumination system 100 for providing a light source for the projector, so it further includes a light source 10 for generating a first light 10', and a condenser lens 12 is arranged in front of the light source 10, usually a lens combination, and the first light ray 10' shoots to the condenser 12, and the condenser 12 condenses the first light 10' to become a second light 12' and projects it to a reflector group 14, usually the reflector group 14 is Composed of one or more reflectors, in terms of the present invention, the reflector group 14 can be divided into a first reflector 141 and a second reflector 142, wherein the first reflector 141 is irradiated by the second light 12' , and reflect a third light 141' to the second reflector 142, and the second reflector 142 reflects a fourth light 142', and this fourth light 142' is directed to a digital micromirror device 2 ( DMD, digital micromirrodevice), and the digital micromirror device 2 changes the inclination angle of the micromirror (not shown in the figure) according to the electronic signal received by itself, and then reflects the fourth light 142' to become the image beam 20 'and captured by the lens 5 to become a projection beam 50', and finally, an effective image area 41' is formed on a screen (not shown in the figure). Of course, non-digital micromirror devices are also available, but generally speaking, digital control is more convenient.

Please cooperate with FIG. 4 , which is a three-dimensional schematic diagram of the optical path generated between the second mirror and the digital micromirror device of the present invention. Wherein, the fourth light 142' reflected by the second mirror 142 will generate a projected area 4 in the digital micromirror device 2 and its surroundings, and the projected area 4 includes an effective illumination area 41 and a distorted light area 43, wherein the The effective illumination area covers the digital micromirror device 2, and the distorted light area 43 is the stray light and is formed around the effective illumination area 41, and further between the projection area 4 and the second reflector 142 Form a projection optical path 4t, including an effective illumination optical path 41t formed between the effective illumination area 41 and the second reflector 142, and a distorted optical path formed between the distorted light area 43 and the second reflector 142 43t, and the shading device 3 is, for example, a shading baffle to block the distorted light path 43t. In this way, after the distortion optical path 43t is blocked, stray light will not appear around the digital micromirror device 2, that is, only the effective illumination area 41 is projected on the digital micromirror device 2, so even if the lens 5 ( Please cooperate with the image circle in Fig. 3) to cover the part outside the effective lighting area 41, because the distorted optical path 43t that will generate stray light has been blocked by the shading device 3 first, and the distorted optical path 43t is also on the shading device 3 A blocked distorted light and shadow 43a is formed, so the surroundings of the digital micromirror device 2 will be dark, and will not be imaged on the screen naturally. Therefore, there is only an effective image area 41' on a screen (not shown in the figure), and the distorted image area 43' produced by the existing projector 1 will no longer exist.

Please refer to Figure 3 and Figure 4 at the same time. It should be noted that if the image circle of the lens 5 can cover a relatively large area, for example, when the lens 5 has a powerful shift function, the image circle of this type of lens is usually larger At this time, it is necessary to prevent the shading device 3 from entering the light cone formed by the image beam 20 ′, otherwise the shading device 3 may be captured by the lens 5 and be imaged on the screen. It can be seen that the idea of the present invention is to confirm where the optical path forming the distorted light area passes, that is, to arrange the shading device 3 in an appropriate position, so that the optical path of the distorted light area will be produced at the front of the digital micromirror device. If the distance is pre-blocked, the problem of stray light is solved in one fell swoop by dredging the bottom of the pot, instead of using more negative methods such as extinction as in the existing technology.

Furthermore, it should also be noted that although the shading device 3 itself needs to undergo matting treatment, which is usually a treatment method selected from matting paint or flocking, there will still be a small amount of light reflected, so the shading device 3 The direction should also be careful not to face the lens 5 , otherwise the image may become blurred. That is to say, the installation direction of the shading device 3 in FIG.

The difference between the present invention and the prior art is that the light that produces the distorted light area is cut off by the shading device 3 before reaching the digital micromirror device 2 and its surroundings, and the light projected on the digital micromirror device 2 is completely limited. In its own right, the present invention is more effective at eliminating stray light and distortion from optical drives than the prior art.

This case has been modified in various ways by people who are familiar with the technology, but it still does not break away from the protection of the scope of the patent application of this case.

Claims (13)

1. A projector with a shading device, comprising: A lighting system for providing the projector with a light source, which further includes: a light source producing light; a condenser lens for concentrating the light; and a mirror for reflecting the light; A micromirror device (MD) is used to receive the light reflected by the reflector and reflect it after being processed; a lens for receiving the light processed and reflected by the micromirror device, and the lens focuses the light into an image; and A light shielding device is arranged between the micromirror device and the lighting system, and is used for shielding the stray light generated by the lighting system. 2. The projector according to claim 1, wherein the reflecting mirror produces a projection area when reflecting the light, including an effective illumination area and a distorted light area, wherein the effective illumination area covers the micromirror device, and the distorted light area is the stray light and is formed around the effective lighting area, and a projection light path is formed between the projection area and the reflector, including a light path between the effective lighting area and the reflection mirror. An effective illumination light path formed between the mirrors, and a distorted light path formed between the distorted light area and the reflecting mirror, wherein the shading device is used to block the distorted light path. 3. The projector according to claim 1, wherein the reflector further comprises: a first reflector for redirecting the light; and A second reflection mirror is used for receiving the light reflected by the first reflection mirror and reflecting the light to the micromirror device. 4. The projector according to claim 1, wherein the shading device is a shading baffle. 5 . The projector according to claim 1 , wherein the shading device is subjected to a matting process. 5 . 6. The projector according to claim 5, wherein the matting treatment is selected from one of matting paint and flocking. 7. A method for eliminating stray light applied to a projector, comprising the following steps: (1) providing a lighting system for providing the projector with a light source; (2) providing a micromirror device for processing and reflecting light from the lighting system; (3) generating a projection light path between the illumination system and the micromirror device; (4) providing a shading device between the illumination system and the micromirror device; and (5) providing a lens for receiving the light reflected by the micromirror device and imaging it, Wherein, the shading device blocks a part of the projection light path, so as to avoid the part of the light from projecting to the periphery of the micromirror device. 8 . The method according to claim 7 , wherein the projected light path can be further divided into an effective projected light path and a distorted light path, and the portion blocked by the shading device is the distorted light path. 9. A micromirror device projector comprising an illumination system, a micromirror device irradiated by the illumination system, a lens receiving light reflected by the micromirror device, and focusing the light into imaging, and the projector The feature of the invention is that a shading device is further arranged between the lighting system and the micromirror device to block a stray light generated by the lighting system. 10. The projector according to claim 9, wherein an effective illumination optical path is further formed between the illumination system and the micromirror device, and a distorted optical path is formed around the effective illumination optical path, wherein the shading The device is located on the distorted light path so that the distorted light path will not reach the micromirror device. 11. The projector according to claim 9, wherein the shading device is a baffle, which directly blocks the light on the distorted light path. 12 . The projector according to claim 9 , wherein the baffle is further subjected to matting treatment, and the matting treatment is one selected from matting paint and flocking. 13 . 13. The projector according to claim 9, wherein the micromirror device is a digital micromirror device.

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