A kind of optical texture that is used for optical projection system
Technical field
The present invention relates to the optical texture of Display projector technology, a kind of optical texture of realizing the micro-display device Projection Display of saying so exactly.
Background technology
The development of information display technology has driven the development of other novel Display Technique.Develop into passive light source LCD display part from self-luminous vacuum device CRT, the flat panel display notion has appearred again in succession, as PDP plasma Display Technique, LCD Display Technique and little Display Technique, wherein PDP and LCD have been widely used in present household products field, and represent DLP, LCoS, LCD of little Display Technique etc., then, will become the main flow of present Display Technique to realize that high definition is shown as feature.
Little Display Technique is an advantage with its micro devices, adopts advanced semiconductor fabrication, combines with the traditional optical technology, can realize large-screen, high definition flat panel display.Press the projection pattern difference, the branch of front projection and back projection is arranged.Over the past two years, be that the technology of representative has obtained very big development and progress with DLP, this mainly is digital technology solution, high definition and high reliability that it is superior.DLP realizes that by a kind of microreflection device DMD signal transmits, and DMD is made up of up to a million micro-reflector mirrors, and each micro-reflector is controlled separately by CMOS, and it can independently rotatablely move, and is each pixel cell in the display frame.Under no driving condition, micro-reflector is smooth, and when irradiate light, it is then with around its fixed axis and with fixing angle tilt, and this moment is for opening (ON) state; When no rayed, it then does rightabout inclination around its fixed axis and with identical fixed angle, and this moment is for closing (OFF) state; These micro-reflectors up to a million can form the picture signal with certain half-tone information under certain pixel electrical signal drives, through the projection lens enlarging projection, can project on the projection screen, realize that the reconstruction of image shows.
As shown in Figure 1 and Figure 2, be the optical projection system schematic diagram of existing projection arrangement, it is the typical structure of U.S. Pat 6726332 described DLP technology.Fig. 1 is the monolithic display projection system, wherein light source 10 is made up of wick 101 and reflector 102, and generation light beam 103, this light beam is behind reflector 102 reflect focalizations, by a color filtering mean---colour wheel (color wheel) 11, colour wheel 11 is by tactic red, green, blue colour filter is formed, when colour wheel is pressed the certain way driving, red from the light beam 103 of light emitted according to what design, green, blue order, successively by colour wheel 11, and by photoconductive tube (light Pipe) 12, light beam is repeatedly reflection in photoconductive tube, in the exit of photoconductive tube, can form and have definite shape and inhomogeneity hot spot, behind condenser 13 and delay lens 14,, enter prism system 17 behind the delayed again lens 16 again through refluxing reflection mirror 15.Prism 17 is made up of the prism 1701 and 1702 with inner total reflection feature, and 1701 and 1702 is glued together, is parallel to each other between two cemented surfaces and keeps certain air distance.Total reflection takes place after the light beam of light source enters 1701, and light beam is reflected to digital micro-mirror display device 18 (DMD).Under certain voltage drives, digital micro-mirror display device 18 (DMD) has " opening " and " pass " two states, when digital micro-mirror display device 18 (DMD) is in " opening " state, DMD micro mirror rotation+12 degree, light beam returns prism 17 and passes through prism 17 through the DMD reflection, enter projection lens projects to projection screen, the image information that light beam carries will be presented on the screen.When digital micro-mirror display device 18 (DMD) " pass " state, DMD micro mirror rotation-12 degree, light beam returns prism 17 through the DMD reflection, but because light beam is when DMD micro mirror rotation-12 is spent, the angle of folded light beam and projection lens is bigger, light beam can not directly enter projection lens by prism 17, and at this moment screen then shows dark state.
Yet, because the illuminating bundle 103 that aforementioned existing apparatus is produced by light source 101, before entering projection lens 19, need through colour wheel, photoconductive tube, condenser, delay lens, refluxing reflection mirror, total reflection prism (TIR), carry out DMD micro-reflector spare at last, when light enters each optics, all there is segment beam to be reflected and loses.Be the optical system of basic structure with the physical optics, the quantity of optical component how much, and optical efficiency what can directly have influence on, and then be directly connected to the size of screen intensity.Yet, adopt the optical texture of above-mentioned traditional TIR prism, because the air gap of TIR prism itself must cause the scattering of light path light, thereby cause light intensity loss; Add that the volume of TIR prism own is bigger, it also is absolutely necessary to the absorption of light, finally influences the brightness of projected picture.
And, because wide-angle reflection mirror cause, after speculum, need add lens to the shaping of illumination light spot, being fit to DMD to the hot spot demand, but this can make illuminating bundle lose about about 2% again.
And, because DMD is fixed on the lower surface position of TIR prism system, just being in the short side direction of trihedral prism, this can make that prism dimensions is bigger.
Its main feature of said structure is to adopt the coaxial optical texture of the heart far away, utilizes the specified conditions and the feature of TIR inner total reflection, realizes the light path conversion of incident ray and reflection ray, thereby realizes the projection amplification and the demonstration demand of image.
In sum, existing optical system is because optical component is more, make that the optical efficiency of optical system is lower, and, the quantity of optics reaches the complexity of optical system more, the whole optical system volume is increased, thereby make projection products be difficult to satisfy that volume is little, in light weight, performance is excellent and the requirement of slimming.
Summary of the invention
The object of the present invention is to provide a kind of optical texture that is used for optical projection system, this structure realization input path is effectively separated with reflected light path, thereby effectively cooperates with the anglec of rotation of DMD micro-reflector, realizes best contrast image.
Another object of the present invention is to provide a kind of optical texture that is used for optical projection system, adopts special illumination path and off-axis optical system, by the optical shaping means, makes the illumination hot spot of incident DMD have high brightness and high uniformity energy.
Another object of the present invention is to be provided for the optical texture of optical projection system, this structure can reduce optical component quantity, reduces the light penetration loss, thereby improves the optical efficiency of whole system, reduces the optical system part, reduces cost.
Another object of the present invention is to be provided for the optical texture of optical projection system, this structure is utilized a special lenses structure, realize that incident ray separates with the reflection ray light path, its purpose is effectively to improve the uniformity of hot spot, and make optical system simple as far as possible, dwindle whole optical projection system volume.
The present invention is achieved in that
A kind of optical texture that is used for optical projection system, this structure comprises: a light source produces light beam; One colour filter device, it matches with a sequencing control, realizes the filtering signals of same red, green, blue three primary colors; One optical integrated device, it makes circular light spot that light source sends through repeatedly reflecting moulding, forms the uniform light spots with certain length-width ratio; One group of optically focused delay lens, hot spot focusing, elimination optical aberration and distortion with definite shape form the desired spot size of DMD; One special prism is positioned at before the DMD, realizes that incident separates with emitting light path; One micro-display device receives the light beam from light source; One projection lens is positioned on the reflected light path of micro-display device, receives reverberation and projects on the screen demonstration of realization image.
Wherein, the delay lens group comprises first lens, is used to eliminate because the optics spherical aberration that light causes and the focusing difference of meridian and sagitta of arc light path reach second lens, focuses on; Inject special prism after the delayed set of lenses of illuminating ray.
The present invention comes down to a kind of space optics and transmits display system, just everybody alleged light engine.In this system, light source and illuminator provide the illuminator of a wide-angle for the space optics transmission system, light enters first lens of delay lens system after focusing on through shaping, eliminate because the optics spherical aberration that light causes and the focusing difference of meridian and sagitta of arc light path, after second lens focus, incide on the DMD by special prism, afterwards through special prism, light optical axis on the prism frontal plane has and departs from, it makes output image enter first eyeglass of projection lens, in this position, image be the heart far away and also with incident light axis from axle, projection lens then makes the image of frontal plane amplify and it is presented on the projection plane.
Realize that the topmost member of the present invention is:
One light source produces illuminating bundle;
One micro-display device is used to modulate the illuminating bundle that comes from light source, and is formed for the reflected image hot spot that projection is amplified;
One special prism, between projection lens, micro-display device, it makes the illuminating bundle illuminating bundle at a certain angle that comes from lighting source enter micro-reflector spare surface, and makes folded light beam inject projection lens, realizes that incident separates with reflected light path;
One projection lens is positioned on the reflected light path of micro-display device, receives reverberation and projects on the screen demonstration of realization image.
Secondly, the present invention also includes:
Filter receives also elimination from the light beam by unwanted ultraviolet of system and infrared band of light source;
Colour wheel is used to receive the spectrum from certain wavelength of light emitted, produces the light beam of the certain color corresponding with picture signal in certain sequence;
Photoconductive tube is used to receive the light beam from colour wheel output, and converts light source normal distribution spectrum to certain length-width ratio dimension and certain brightness uniformity hot spot;
Collector lens is used to adjust the photoconductive tube output facula and makes its optical system and the bulb numerical aperture is complementary, and makes this hot spot export micro-display device to.
In order accurately to control Projection Display, wherein:
Special prism is the prism wedge structure, and it is adjacent with micro-display device, and its plane one side is adjacent with the micro-display device surface; The illuminator light beam will enter little reflective display device through this prism wedge, also will pass through this prism wedge through the folded light beam of micro-reflector spare; The minimum cone angle of prism wedge is between 0 to 15 degree.
Angle between the frontal plane of illuminating bundle and special prism is between the 20-50 degree.
The angle of micro-display device and camera lens optical axis is 0<θ<15 degree.
Spend less than-3 ∽ 3 through prism wedge and camera lens chief ray angle β from the light of micro-display device reflection.
The present invention has adopted special prism and telecentric beam path to reach the feature that designs from axle, best contrast-response characteristic can be provided, by special prism structure, relative DMD plane of incidence, illumination path provides the illuminating bundle of maximum angle, wherein the delay lens group can compensate optical axis some depart from.
With respect to projecting light path, illuminator is from axle, but for the light that reflects from DMD, though one off-axis is arranged through special prism and illuminator, but to projection optical axis, optical projection system itself is the heart far away, therefore non-relatively core structure far away, its volume is less, and its back of the body defocus distance can reduce.
The limited inclination of the relative optical projection system with DMD of special prism makes light have when ON and the OFF bigger angle separately by the DMD micro mirror, has improved the contrast of system.
In addition, the special prism of wedge shape can also adopt other similar structures to substitute, and is 1/2nd special lenses replacement as available curved surface.
Therefore, another kind of implementation of the present invention is:
A kind of optical texture that is used for optical projection system, it comprises: a light source produces light beam; One group of lens, this prism has focussing force between light source, micro-display device; One special lenses is positioned at before the DMD, realizes that incident separates with emitting light path; One micro-display device receives the light beam from light source; One projection lens is positioned on the reflected light path of micro-display device, receives reverberation and projects on the screen demonstration of realization image.
Above-mentioned special lenses, at least one surface of two light transmitting surfaces of special lenses is a curved surface.Generally be that its transparent surface of injecting light beam is a curved surface, another logical light face is the plane.
This optical texture not only is used for back-projection system, also can be used for front projection system.For front projection system, can carry out light path through illuminator and turn back, thereby reduce volume, satisfy the front projection volume.
Advantage of the present invention is:
Projection Display optical texture of the present invention, utilize special prism to substitute the design of the TIR prism of traditional design, simply and cheaply realized of the requirement of little demonstration reflection device, also can effectively dwindle the volume of optical system by the use of speculum to optical system.
Projection Display optical texture of the present invention utilizes less optical element, reduces the loss that is caused by optical element surface, the brightness that helps improving optical system.
Projection Display optical texture of the present invention utilizes the operation principle of special lenses 27 and inclination micro-display device 28, can effectively strengthen micro-display device 28 in the angle that ON and OFF light separate, and helps improving the contrast of optical system.
Description of drawings
Fig. 1 is a prior art Projection Display optical system schematic diagram;
Fig. 2 is the total reflection prism structure chart that prior art adopted;
Fig. 3 is the optical system diagram of one embodiment of the invention;
Fig. 4 is that special prism of the present invention requires schematic diagram;
Fig. 5 is the status requirement structure chart of micro-display device of the present invention and optical projection system;
Fig. 6 is the claimed structure figure of micro-display device reflection ray and optical projection system optical axis;
Fig. 7 is the schematic diagram that separates of incident ray and emergent ray;
Fig. 8 is the structural representation of special lenses structure of the present invention.
Embodiment
Describe enforcement of the present invention in detail below in conjunction with accompanying drawing.
With reference to figure 3, the present invention is by light source 20, colour wheel 21, and photoconductive tube 22, the first collector lenses 23, the second collector lenses 24, delay lens 25, speculum 26, special prism 27, micro-display device 28, projection lens 29 is formed.
Optical system operation principle of the present invention, luminous by light source 20, the visible light in white broadband is provided, converge at colour wheel 21, colour wheel 21 is made up of blue, green and red colour filter, and light produces redness, green and blue homogeneous beam by after rotating colour wheel 21 successively by certain time sequence; Light beam enters photoconductive tube 22 through colour wheel 21, and photoconductive tube 22 plays a light integrator, and the circular light spot homogenizing entering photoconductive tube 22 becomes the rectangular light spots that a good uniformity has certain length-width ratio.First collector lens, 23, the second collector lenses 24 and delay lens 25 have modulating action, make the spot size of illuminator, are complementary with the relative aperture of micro-display device 28; Incide on the micro-display device 28 by special prism 27 from the light of delay lens 25 outgoing.Speculum 26 changes optical path direction, makes the light path system volume reduce; Special prism 27 (it is a wedge structure, and two transparent surfaces are all the plane) can effectively separate the angle between illuminator and the optical projection system in light path, make illuminator and optical projection system satisfying under the optical aperture requirement, does not interfere; Special prism 27 also can effectively help to proofread and correct the aberration by the inclination generation of micro-display device 28.The light that incides micro-display device 28 enters projection lens 29 through special lenses 28 again, and projection lens 29 enlarging projections are to screen.
Projection Display optical texture of the present invention, utilize special prism 27 to substitute the design of the TIR prism of traditional design, simply and cheaply realized of the requirement of little demonstration reflection device, also can effectively dwindle the volume of optical system by the use of speculum 26 to optical system.
Projection Display optical texture of the present invention utilizes less optical element, reduces the loss that is caused by optical element surface, the brightness that helps improving optical system.
Projection Display optical texture of the present invention utilizes the operation principle of special lenses 27 and inclination micro-display device 28, can effectively strengthen micro-display device 28 in the angle that ON and OFF light separate, and helps improving the contrast of optical system.
Fig. 4 is the structural representation of special prism 27.As shown in the figure, its profile is a wedge, but its logical optical surface is made up of two planes; When 15 ° of any angles of 0 ∽ are satisfied at composition angle, two planes, when the illuminator certain angle incides the first surface 2701 of prism, because its refraction action makes transmitted light 2702 incide micro-display device 28 surfaces.When micro-display device micro-reflector during with+12 °, reflection ray is then to penetrate with incident ray certain angle direction.
Fig. 5 has provided the off-axis angle of projecting light path 29 with special prism 27 and micro-display device 28.Because micro-display device is realized its ON, OFF state with fixed angle, when projection optical axis and special mirror, micro-display device optical axis are 15 ° of any angles of 0 ∽, at the ON state, the micro-display device micro-reflector is driven by optical path signal, rotate+12 °, this moment, the light through special prism 27 reflections then entered camera lens along the optical axis of projection lens 29; At the OFF state, through the light of micro-display device reflection then with bigger angle deviating projection lens optical axis, thereby realize the high contrast performance of display image.
Fig. 6 further illustrates the effect of special prism 27, when the directional light 60 of telecentric light system incides the first surface 2701 of prism at a certain angle, because its refraction action makes transmitted light 2702 incide micro-display device 28 surfaces.When micro-display device micro-reflector during with+12 °, 61 of reflection rays are to penetrate with incident ray 60 certain angle directions.When micro-reflector is in the ON/OFF state, on it micro-reflector rotate respectively+12 °/-12 °, reflection ray 61 has a minute angle with projection optical axis 62 to be departed from, its off-axis angle is-3 °<β<3 °.
Fig. 7 has provided special prism 27 and has realized the situation that incident, reflection optical axis separate.
When micro-display device was the ON state, reflection ray entered projection lens 29 fully; When micro-display device was the OFF state, reflection ray departed from projection optical axis and does not enter projection lens with wide-angle more.
Fig. 8 is a kind of special lenses structure, and it is functionally equivalent to special prism.This special lenses structure 117, its function is identical with special prism 27, effective separation of reflected light path in the time of can realizing micro-display device ON/OFF state.The difference of it and special prism 27 is that the logical light face of special prism 27 is a curved surface, and two logical optical surfaces 1171 of special lenses 117 and 1172 are curved surface, or wherein a surface is a curved surface, and a surface is the plane.