CN1183773C - Projection televisions with morrors incident on holographic screens - Google Patents

Abstract

The present invention relates to a television projection screen (22) provided with a three-dimensional holographic element (26) arranged on a thin film base electrode (24). The screen (22) is used for collecting light within a certain incident angle range and redirecting the light to a closely forward direction. A vertical holographic element and a horizontal holographic element which have variable gains within the range at a horizontal viewing angle of (+/-)40 degrees and the range at a vertical viewing angle of (+/-)20 degrees can be superimposed. Image projection tubes (14, 16, 18) project an image onto at least one reflecting mirror (20) reflecting the image along a light path, and the light path converges to form a projection angle phi of approximately 0 degree to 30 degrees relative to the orthogonal axis of the screen. Each of the projection tubes (14, 16, 18) can be provided with an independent reflecting mirror. The holographic element (26) redirects the reflected image to form a display angle of 0 degree to 5 degrees relative to the orthogonal axis of the screen. The holographic element (26) also forming an interference pattern effectively reduces the color deviation generated in a displayed image owing to off-axis projection under other conditions to realize the existence of the color deviation of 2 to 5 within the incident angle range of 0 degree to 30 degrees.

Description

Employing has the projection TV of the hologram screen of speculum

Invention field

The present invention relates to the projection receiver field, specifically, the present invention relates to have a kind of projection receiver towards the projection source of at least one speculum orientation, said speculum will reflex to the back side of hologram screen from the light of light source.This hologram screen collects in the light in certain ranges of incidence angles, and with said light turn to into the direction more parallel with respect to the optical axis of said screen quadrature.This hologram screen and one or more combination have reduced colour cast significantly, have improved brightness, and can reduce the casing degree of depth significantly.

Background technology

Colour cast is defined as: red/the blue or green/blue ratio of the white image that records in the high-high brightness position of vertical angle of view, formed in the projection screen center by projected image red, green and that the drop shadow blue pipe sends is in the variation of different horizontal view angles.

The colour cast problem is because different colours (as red, blue and green) image needs at least three image projectors to cause.Projection screen is received image from least three projectors at first side joint, and shows these images in second side by the optical dispersion of controlling all displayed image.Be generally green, and a projector that is usually located at projector array center has first light path that is orthogonal to the screen orientation substantially.Be generally red and blue, and be usually located at least two projectors of drop shadow green of the array center relative both sides of device, have the light path of assembling to first light path with the incidence angle of non-orthogonal orientations respectively.Red, blue projector has caused colour cast with respect to the non-orthogonal relationship of screen and green projector.The result of colour cast is that the tone of each position may be inequality on screen.It is relatively poor that the state that the tone difference is big is commonly called the white uniformity.The more little white uniformity of colour cast is good more.

Mark colour cast with number, the colour cast that wherein lower numeric representation is less and the white preferably uniformity.According to current rules, measure the red, green, blue brightness value of screen center from each horizontal view angle, usually from least approximately-40 ° to+40 °,, and be incremental spacing with 5 ° or 10 ° to about-60 ° to+60 ° scope.Positive negative angle is represented the horizontal view angle in screen center right side and left side respectively.These measured values obtain at place, peak value vertical angle of view.0 ° of data of locating the normalization red, green, blue.Estimate with following one or two equation (I) with (II) at each angle place:

$C\left(\mathrm{\θ}\right)=20\·{\log }_{10}\left(\frac{\mathrm{red}\left(\mathrm{\θ}\right)}{\mathrm{blue}\left(\mathrm{\θ}\right)}\right)---\left(1\right)$

$C\left(\mathrm{\θ}\right)=20\·{\log }_{10}\left(\frac{\mathrm{green}\left(\mathrm{\θ}\right)}{\mathrm{blue}\left(\mathrm{\θ}\right)}\right)---\left(\mathrm{II}\right)$

Wherein θ is arbitrarily angled in the scope of horizontal view angle, and C (θ) is the colour cast at place, θ angle, and red (θ) is the red brightness value in place, θ angle, and blue (θ) is the blue brightness value in place, θ angle, and green (θ) is the green brightness value in place, θ angle.The maximum of these values is colour casts of screen.

Usually, colour cast should be greater than 5 these commercial acceptable demarcation screen design loads.Other Engineering and design constraint need colour cast bigger than 5 when having, the colour cast performance of even now is undesirable, and usually causes the inferior relatively poor image of the white uniformity of viewing effect.

The shape that the projection screen of projection receiver normally adopts extrusion to utilize one or more figuratum rolls to form the thermoplastic sheet surface is made.Its structure is generally the lenticular lens element array, is also referred to as lenslet array.These lenticular lens element can be formed on the one or both sides of identical board-like material; Perhaps only be formed on the side of different plates, again that these are different plates for good and all is combined into a lamination unit, or the employing alternate manner is mounted adjacent one another and make it have the function of lamination unit.In many designs, a surface of screen constitutes a Fresnel Lenses and forms light scattering.The trial that prior art reduces colour cast and improves the white uniformity only concentrates on two aspects of screen.A shape and the layout that the aspect is a lenticular lens element.Another aspect be screen material or wherein some part be the degree of control light scattering doping optical scatter.The example of these trials is the row patent documentation as follows.

At U.S. Pat .4, in 432,010 and US.4,536,056, projection screen comprises a printing opacity lenticular lens sheet with input surface and exit surface.The characteristics on input surface show the convex lens profile aspect of horizontal dispersion, and the ratio (Xv/R1) of its convex lens degree of depth Xv and paraxial radius of curvature R 1 is in 0.5 to 1.8 scope.This profile extends along optical axis direction, and forms many aspheric surface input convex lens.

What adopt usually is the screen that bilateral has convex lens.This screen has cylinder input lenticular elements and is formed on the cylindrical convex lens element of this screen output surface side on its input surface, and the light absorbing zone that is formed on not converging light part on the output surface.The input and output lenticular elements all is circular, ellipse or hyperbola, and by under (III) expression that establishes an equation:

$Z\left(x\right)=\frac{{\mathrm{<figure-callout\; id="2"\; label="Cx"\; filenames="C9881339800201.png"\; state="\{\{state\}\}">Cx</figure-callout>}}^2}{1+{[1-(K+1)C^2{x}^2]}^{\frac{1}{2}}}---\left(\mathrm{III}\right)$

Wherein C is a principal curvatures, and K is the constant of conic section.

In addition, lens can also have and wherein added the curve that is higher than quadratic term.

In the screen that constitutes with this bilateral convex lens, input lens and output lens have been stipulated or the position that constitutes between the lenticular elements of these lens concerns.For example, U.S. Pat .4,443,814 are instructed, and determine the position of input lens and output lens in such a way: the lens surface of lens is at the focus place of another lens.Japan Patent JP.58-59436 also instructs: the eccentricity of input lens equals to constitute the inverse of the material refractive index of convex lens substantially.U.S. Pat .4,502,755 also instructions, be combined into the plate that two bilaterals have convex lens in the following manner: the optical axial plane of each convex lens is mutually the right angle each other, and forms this bilateral convex lens as follows: input lens and output lens in lens periphery are asymmetric about optical axis.U.S. Pat .4,953,948 also instructions have only the optical convergence position at input lens trench place should be partial to the surface that output lens is watched a side, so that the tolerance of optical axis misalignment and thickness difference can be bigger, or make the colour cast can be less.

Except these reduced the various schemes of colour cast or white inhomogeneities, other schemes of improving the projection screen performance were at improving image brightness and guaranteeing suitable visual field in level and vertical direction.The main points of these schemes can be from U.S. Pat .5,196,960 find, the document has been instructed a kind of bilateral lenticular lens sheet, it comprises input lens layer with input lens and has output lens and its lens surface is formed on input lens optical convergence point and near its output lens layer, wherein input lens layer and output lens layer constitute by the thermoplastic resin of substantially transparent, and output layer comprises the light scattering particulate at least, and the light scattering characteristic between input lens layer and the output lens layer exists difference.The input lens group is a kind of post lens.Output lens is made of one group of output lens layer, and its each layer all has a lens surface to be positioned near the face at each lens light convergent point place of input lens layer or its.Light absorbing zone is formed on the part of not converging light of output lens layer.This screen design provides good horizontal view angle, less colour cast and brighter picture, and be easy to make with extrusion.

Although in the projection screen design, improved research existing many years, still constantly need to find improvements.And, also successfully do not surpass some benchmark.The incident angle that the physical dimension of image projector limits is called the α angle herein, generally is defined as greater than 0 ° and is less than or equal to about 10 ° or 11 °.The size of image projector makes the α angle substantially can not be near 0 °.In the α angular region less than about 10 ° or 11 °, as according to equation (I) and (II) determined, the optimum colour bias that has realized can be about 5.In the α angular region greater than about 10 ° or 11 °, the optimum colour bias that has realized can not have commercial value.In fact, have at projection receiver and also on market, do not occur greater than about 10 ° or 11 ° α angles.

There is an obvious and undesired consequences at little α angle, promptly must have the very big casing degree of depth to hold projection receiver.The big degree of depth is to hold the direct result with little incidence angle (α) light path.For the image projector and optical element of intended size, only can reduce incident angle by the optical path length that increases between image projector or its optical element and the screen.

Reduce the technology of projection TV casing size, generally depend on the layout of a plurality of speculums that are used for folding long light path.These effort that reduce colour cast are finally owing to possible incident angle scope little (even using speculum) is restricted.

It is DMP-128 that Polaroid Corp sells a kind of label ^Photopolymer, Polaroid Corp can be made into the 3D hologram element with the method that patent rights is arranged.US.5,576,853 have described the part of this holography manufacture method.Holographic photopolymer is generally used for coming the recording holographic image by coherent light being resolved into illumination light and reference light.Illumination light is radiated on the reference object.Be radiated on the photopolymer medium from the object beam reflected with from the reference beam of object next door process, this medium comprises the photosensitive photography composition that can develop.The light wave of two light beams is interfered mutually, and promptly they produce standing wave pattern by the interference of structure and reconstruct, and this pattern had the sinusoidal crest of part photography composition exposure and the zero point of topical composition not being exposed.When the photography medium developed, corresponding interference figure just was recorded in the medium.With this medium of coherent reference rayed, the visual reproduced of object come out, and can watch in its angular field of view.

Because the reference light of being had a few on light that all illuminated points send from the object and the hologram is interfered mutually, so represent the interference figure that hologram write down of common holographic object very complicated.Should be able to produce a blank hologram by writing down blank object (by effective interference of two reference beams), interference figure wherein is more regular.In the case, interference figure is similar to diffraction grating, but the spacing of diffraction grating and resolution be formed with more large scale convex lens unit so that projector is from behind compared much thin along the projection screen of specific direction bending or refracted ray.

For setting up DMP-128 ^The institute of photo-induced polymer holographic produce market does in the effort, a kind of as multiple suggestion, and Polaroid Corp has proposed the projection TV three-dimensional holographic screens.This suggestion is based on the desirable high brightness and resolution of Polaroid Corp, low manufacturing cost, avoid in low weight and the shipment being subjected to the biplate screen frayed advantage propose.Polaroid Corp never proposed any concrete holographic structure that can be made into this line holographic projections video screen volume hologram, also never considered the colour cast problem of holographic or other any kind projection TV screen.

In a word, although carried out a lot of developmental researches for many years, have less than 5 to provide, even be significantly smaller than 5 colour cast, or have be low to moderate 5 colour cast and the α angle greater than the projection receiver of the screen of 10 ° or 11 °, but make new advances differently with the continuous variation of traditional projection screen lenticular elements shaped position and scattering object, solving aspect the colour cast problem not progress.And, can be used for projection screen although advised the 3D hologram element, owing to do not relate to the colour cast problem, also just never did trial aspect the projection TV of three-dimensional holographic screens providing.Therefore, have a demand that improves the colour cast performance greatly and can be loaded into a projection receiver in the littler casing to a kind of for a long time, also be not met.

Brief summary of the invention

Obviously improved colour cast performance (measuring) according to the projection receiver of invention scheme teaching herein, made incidence angle α can reach 2 or littler colour cast less than the projection receiver in 10 ° or the 11 ° of scopes by order of magnitude.And, this colour cast performance obviously can provide meet commercial require be loaded in the very little casing and the projection receiver of incidence angle up to 30 °.According to the present invention, these factors have further been strengthened by adopting one or more speculums to prolong optical path length.The colour cast performance of this big α angle receiver little α angle receiver with traditional at least is the same good, for example reach to equal 5 colour cast, and under the situation of little α angle receiver and relative less casing, be expected near or reach and be low to moderate about 2 value.

These effects obtain by abandoning fully pushing the lens Screen Technology.On the contrary, according to the present invention program's projection receiver, have by being formed on the substrate, as the screen of the formation of the 3D hologram element on the polyethylene films such as Mylar .

This three-dimensional holographic screen of initial exploitation is because it has in high brightness, high-resolution, low manufacturing cost, low quality and resist two screens outstanding advantage aspect the wearing and tearing mutually in processes such as shipment.Whether the same with conventional screen at least when good in the optical characteristics that detects this three-dimensional screen, found the colour cast of this three-dimensional holographic screen.Resulting three-dimensional holographic screen colour cast performance is low unexpectedly according to equation (I) with (II).The restriction prior art is improved the obstacle that improves and is eliminated fully.In addition, can develop littler casing now with bigger incidence angle α projection structure.

According to the present invention program teaching herein, the projection TV with outstanding characteristic three-dimensional holographic screen comprises: the projector of at least three different colours images; By being arranged on the projection screen that the 3D hologram element constitutes on the substrate, this screen is received image from projector at first side joint, and shows this image and control the light scattering of shown image simultaneously in second side; Wherein each image projector has an axis of projection, and these projectors are like this configurations, makes any two adjacent image projectors have the axis of projection of convergence, and these axis of projections define an incidence angle α; And representative has the 3D hologram element of the convex lens cubical array that is used to effectively reduce displayed image colour cast structure, said screen greater than zero and less than or be approximately equal to have in the 30 degree ranges of incidence angles and be less than or equal to about 5 colour cast, determine as the maximum that obtains according to one of following formula at least:

$C\left(\mathrm{\&theta;}\right)=20\&CenterDot;{\log }_{10}\left(\frac{\mathrm{red}\left(\mathrm{\&theta;}\right)}{\mathrm{blue}\left(\mathrm{\&theta;}\right)}\right);$

$C\left(\mathrm{\&theta;}\right)=20\&CenterDot;{\log }_{10}\left(\frac{\mathrm{green}\left(\mathrm{\&theta;}\right)}{\mathrm{blue}\left(\mathrm{\&theta;}\right)}\right)$

Wherein θ is arbitrarily angled in the scope of horizontal view angle, and C (θ) is the colour cast at place, θ angle, and red (θ) is the red brightness value in place, θ angle, and blue (θ) is the blue brightness value in place, θ angle, and green (θ) is the green brightness value in place, θ angle.Can expect that the colour cast of screen less than 5, for example is less than or equal to 4,3 or even 2.

With regard to known 10 ° or incidence angle place, 11 ° of left and right sides obstacle, greater than 0 ° be less than or equal in incidence angle first subrange about 10 °, the colour cast of screen all is less than or equal to about 2 at all incident angles; And about greater than 10 ° and be less than or equal in incidence angle second subrange about 30 °, the colour cast of screen all is less than or equal to about 5 at all incident angles.

This screen also comprises the strengthening part of a printing opacity, as what constitute with one deck acryhic material of thickness in the scope of the 2-4mm left and right sides.Substrate comprises long-life transparent watertight film, as the pet resin film.This substrate can be the film of thickness in 1-10 mil scope.Have been found that the thickness about 7 mils is enough to support the 3D hologram element.The thickness of film and performance are irrelevant.The 3D hologram element has the thickness that is not more than in about 20 micrometer ranges.

According to an aspect of the present invention, said projection TV is provided with at least one speculum along the light path between image projector and the screen.These image projectors separately or the image that together they is produced separately project on the speculum, said speculum reflexes to first side of screen with these images, and defines a projected angle for each image with respect to the optical axis with the screen quadrature.Projection screen utilizes speculum to compile and turns to these images that reflex on it, makes the image that shows on screen second side become one to show the angle with respect to the optical axis with the screen quadrature, shows that wherein angular region is from 0 to 5 °.Said hologram screen is assembled the incident light in certain ranges of incidence angles, and to launch these light near the straight line direction vertical with said normal axis more.

According to a further aspect in the invention, by with a plurality of hologram screen elements and/or the stacked colour cast performance that can further improve projection screen of collimating element.For example, can stacked vertical and straight horizontal line style Fresnel Lenses in the behind of a hologram screen, with the required variation of realization light transmission features in certain horizontal or vertical angular field of view.Perhaps, can a plurality of hologram screen elements that have the light transmission features variation in certain angular field of view are stacked.According to the embodiment of a reality, stacked at least two holographic elements, one provides predetermined variation in the scope of vertical angle of view, and another provides predetermined variation in the scope of horizontal view angle.Like this, just can be adjusted in the brightness of image in the useful angular field of view and make it to reach best, to make full use of available illumination.In addition, with holographic element and/or collimating element is stacked can adapt to multiple performance index request with the acceptable cost, because the manufacturing cost of linear change element is lower than the cyclic variation element.For example, can adopt pressure rolling or roll milling technology to produce linear change Fresnel element with the cost that is low to moderate circular Fresnel Lenses cost 25%.Similarly, the linear change holographic mother is also comparatively simple and with low cost than the circular mother matrix that limits the bidimensional variation.

Description of drawings

At present more preferred exemplary embodiments have been represented in the accompanying drawings.Should be appreciated that the present invention is not limited to these embodiment as example, but under the prerequisite of design that does not break away from the claim embodiment and scope, can make change.In said accompanying drawing:

Fig. 1 is the projection TV schematic diagram of expression according to the present invention program of this paper instruction.

Fig. 2 is a rough schematic view of explaining the used projection television arrangement of the present invention program.

Fig. 3 is the projection screen end view according to the present invention program's reinforcement.

Fig. 4 is the schematic diagram of another embodiment of projection screen, and said screen has two overlapping holographic elements that change in gain is arranged respectively in level and vertical angle of view scope.

Fig. 5 is that holographic element vertically stacked that the expression level changes or during not stacked the holographic element of vertical change, as the curve chart of the white peak brightness ratio of horizontal view angle function.

Fig. 6 is the schematic diagram with another embodiment of stacked holographic element and collimation screen layer.

Fig. 7 is another rough schematic view that is used to explain the present invention program's projection television arrangement.

Fig. 8 is at 10 °, on the vertical plane of 20 ° and 30 °, to φ _vProjected angle at the point of central region, records from ± 20 ° of verticals angle of view, as the brightness curve figure of white peak brightness percentage.

Fig. 9 is another rough schematic view that is used to explain the present invention program's projection television arrangement.

Figure 10 is on 0 ° of horizontal plane, for φ _hProjected angle, red/green and red/blue inclined to one side curve chart of observing from ± 40 ° of horizontal view angles.

Figure 11 is on 0 ° of horizontal plane, for φ _hProjected angle, at the point of central region, the screen intensity curve chart that is recording from ± 40 ° of horizontal view angles as white peak brightness percentage.

Figure 12 is on 15 ° of horizontal planes, for φ _hProjected angle, red/green and red/blue inclined to one side curve chart of observing from ± 40 ° of horizontal view angles.

Figure 13 is on 15 ° of horizontal planes, for φ _hProjected angle, at the point of central region, the screen intensity curve chart that is recording from ± 40 ° of horizontal view angles as white peak brightness percentage.

Figure 14 is on 30 ° of horizontal planes, for φ _hProjected angle, red/green and red/blue inclined to one side curve chart of observing from ± 40 ° of horizontal view angles.

Figure 15 is on 30 ° of horizontal planes, for φ _hProjected angle, at the point of central region, the screen intensity curve chart that is recording from ± 40 ° of horizontal view angles as white peak brightness percentage.

Figure 16 is on 45 ° of horizontal planes, for φ _hProjected angle, red/green and red/blue inclined to one side curve chart of observing from ± 40 ° of horizontal view angles.

Figure 17 is on 45 ° of horizontal planes, for φ _hProjected angle, at the point of central region, the screen intensity curve chart that is recording from ± 40 ° of horizontal view angles as white peak brightness percentage.

Figure 18 is another rough schematic view that is used to explain the present invention program's projection television arrangement.

Description of a preferred embodiment

Fig. 1 schematically shows a projection receiver 10.The projection cathoderay tube 14,16 and 18 of lining up array 12 produces red, green and blue image respectively.These cathode ray tubes also dispose lens 15,17 and 19 separately.The image that throws the away mirror 20 that is reflected reflexes on the projection screen 22.Can also adopt additional reflector according to the concrete structure of light path.Green cathode ray tube 16 is along light path 32 projection green images, and this light path is orthogonal to the screen orientation substantially.In other words, the center line of light path and screen meet at right angles.Red and blue cathode-ray pipe has light path 34 and 36 respectively, and these two light path non-orthogonal orientations ground are assembled to first light path 32 with incidence angle α.This incidence angle has caused the problem of colour cast.

Screen 22 comprises the 3D hologram element 26 that is arranged on the substrate 24.Holographic element 26 is the master hologram printingouts that are formed with diffraction pattern, and this hologram pattern can be allocated the distribution of three projectors 14,16 and 18 light energy outputs, and it is changed on screen height and/or Width.In a preferred scheme, hologram is the centre type hologram, and the light that it will incide on the holographic element in certain ranges of incidence angles turns to, and more directly outgoing forward.This screen is imported the image that a surperficial side 28 receives from projector first, and shows these images in the second output surface side 30, and controls the light scattering of all displayed image.

Preferably, substrate is a long-life transparent watertight film, as the pet resin film.The a kind of of this class film is can be from E.I.du Pont de Nemours ﹠amp; Co. the Mylar that obtains of company ^The board product.This film substrate has the thickness in the 1-10 mil scope, equals 0.001-0.01 inch or 25.4-254 micron.The film that has been found that 7 mil left and right thicknesses is enough to support the 3D hologram element.The general performance with screen of the thickness of film has nothing to do, and colour cast performance especially usedly adopts different film thicknesses.3D hologram element 26 has the thickness that is not more than in about 20 micrometer ranges.

Three-dimensional holographic screens can obtain from two sources at least.Polaroid Corp utilizes the DMP-128 of the wet chemical process of patent rights with it ^The photopolymer material is made the 3D hologram element.This method comprises: form the diffraction holographic element on photopolymer, this holographic element can comprise the screen change in gain in level and/or the vertical angle of view scope.With coherent light the photo-induced polymer holographic medium is exposed and can prepare holographic mother, this coherent light comprises reference beam and changes plane pattern and reflect light beam from having the light and shade corresponding with required change in gain.

Be used for the three-dimensional holographic screens above-mentioned and projection receiver that the application's claims propose, its preferred embodiment is that Polaroid Corp utilizes patented wet chemical process to make according to following performance index:

Horizontal half angle of view: 38 ° ± 3 °,

Vertical half angle of view: 10 ° ± 1 °,

The screen gain: 〉=8,

Colour cast :≤3, wherein level and vertical angle of view record according to conventional method, screen gain is to be orthogonal to screen when measuring, the light intensity and the merchant of being divided by of watching surperficial back from the light source directive from the light intensity of watching surperficial front directive beholder, and colour cast is measured by above-mentioned method.As said in the summary of the invention, the colour cast performance of 3D hologram projection screen excellence is all beyond one's expectations.

Fig. 2 is the rough schematic view of projection TV, wherein in order to explain that the colour cast performance omitted speculum and lens.The optical axis 34 and 36 of red and blue cathode-ray pipe 14 and 18 is with incidence angle α symmetric orientation with respect to the optical axis 32 of green cathode ray tube 16.The minimum-depth D of casing is determined by the distance between screen 22 and the cathode ray tube trailing edge.Should be appreciated that the α angle is more little, cathode ray tube each other the closer to, and also must and screen separate with make it and each ray tube between leave the gap.When the α angle enough hour, this interference was inevitable.This will have to increase the minimum-depth D of casing.On the contrary, the α angle is big more, and cathode ray tube can more close screen 22, thereby reduces the minimum-depth D of casing.

In the side of watching of screen 22, two horizontal angles of half field-of view with-β and+β represents.The aggregate level angle of visual field together is 2 β.This angle of half field-of view usually can be in ± 40 ° to ± 60 ° scope.Be one group of special angle θ in each half-angle, can measure colour cast therein, and determined according to above-mentioned equation (I) with (II).

With regard to the obstacle at known 10 ° or incidence angle place, 11 ° of left and right sides, greater than 0 ° be less than or equal in incidence angle first subrange about 10 °, the colour cast of three-dimensional holographic screen all is less than or equal to about 2 in all angles; And about greater than 10 ° and be less than or equal in incidence angle second subrange about 30 °, the colour cast of screen all is less than or equal to about 5 in all angles.Can suspect that the colour cast that is less than or equal in first subrange about 2 also can realize in second subrange of bigger incidence angle.

With reference to figure 3, substrate 24 comprises a hyaline membrane, aforesaid Mylar .The photopolymer material that forms 3D hologram element 26 is placed on the rete 24.The photopolymer material that is fit to is DMP-128 .

This screen 22 can also comprise the strengthening part 38 of a printing opacity, as acryhic material, resembles polymethyl methacrylate (PMMA) or the like.Also can use makrolon material.Strengthening part 38 is thickness stratified materials in about 2-4mm scope.Screen 22 and strengthening part are coherent each other by the interface 40 of 38 of hologram layer 26 and strengthening parts.Can adopt adhesive, radiation and/or heat bonding technology.Following one or more processing can also be done in the surface 42 of reinforced layer: painted, and anti-dazzle, applying coating and coating anti-scratch coating.

Each surface and/or its techonosphere of screen, can comprise other optical lens or convex lens array, aspect control projection screen other performance characteristics except the colour cast performance under the prerequisite of the colour cast performance that does not weaken the improvement of 3D hologram projection screen, finish as the traditional projection screen of known usefulness.Fig. 4 has represented the change that first is such, wherein has at least two holographic elements superimposed or stack.According to shown in embodiment, in ± 40 ° of field ranges, have first holographic element that horizontal gain changes, and in ± 20 ° of field ranges, have second holographic element that vertical gain changes and be stacked together.Shade among the figure indicates the variation of gain, but when not having illumination, actual holographic element shows as in its surface range simply scattering.Level and the overlapping effect of vertical gain variation holographic element are equivalent to the centre type holographic element substantially; But the brightness value in the horizontal direction will be with different rate variation with vertical direction, and this is because the horizontal extension scope is more much bigger than extends perpendicular scope.

Fig. 5 is the screen center point place that records in ± 40 ° of horizontal view angle spreading ranges screen intensity curve chart as white peak brightness percentage.Brightness when two lines among the figure represent respectively that only employing level changes holographic element and adopt overlapping level and the brightness during the vertical change holographic element.Level brightness during with overlapping holographic element changes the performance when being equivalent to have only horizontal holographic element substantially, or improvement is arranged slightly.

When the various performance index scope of the holographic screen of design, be difficult to make screen to reach all required performance characteristicses simultaneously.Stack and to make different requirements, treated respectively as the level variation and the vertical change of gain.This scheme is not limited to two holographic elements that stack, and also can be applied to the holographic element that other stacks, and for example sees through the others performance of light with the control screen.

Fig. 6 has represented another kind of variation, wherein is stacked with the linear pattern Fresnel Lenses on the centre type holographic element (promptly having level and vertical gain changes), to realize level and rotation vertical collimation effectively.Since the linear pattern Fresnel Lenses can than circular Fresnel Lenses more at an easy rate pressure rolling or roll-in come out, so present embodiment is desirable on the cost meaning.Circular Fresnel Lenses accounts for 60% of conventional screen cost.The cost of linear pattern Fresnel Lenses approximately is 25% of a circular Fresnel Lenses.So, can save 30% cost (that is: (25%+25%) * 60%=30%).For for the holographic element of above-mentioned level of discussing and rotation, if desired, the linear pattern Fresnel Lenses can change in level and/or vertical angle of view scope, so that change focal length, and has nothing to do with vertical and horizontal extension scope.Two stacked linear pattern Fresnels can be placed on the holographic element back according to any order.

Another aspect of the present invention is to design the back projection type TV that has significantly reduced the casing degree of depth.Especially, back projection TV of the present invention can comprise a plurality of image projectors, and wherein the axis of projection of each projector does not all overlap with the normal axis of screen.And the present invention this on the one hand can provide a kind of back projection TV, each image projector wherein all has one by the axis of projection that tilts with the folded projected angle φ of screen normal axis.TV of the present invention can be proofreaied and correct the projected angle φ above 30 °, and to be presented at the image on the screen according to the demonstration angle guiding that is become with the screen normal axis, the scope that wherein shows the angle is 0 to 5 °.

For example, television design of the present invention can adapt to the projected angle that comprised wide-angle, so that reduce the required casing degree of depth more.Fig. 7 has represented one according to γ in the plane of normal to screen 22 _vThe speculum 20 of angular orientation is so that projection cathoderay tube 14,16 and 18 is incident upon the image on the speculum 20, according to having extreme value tilt angle φ in the vertical plane _vProjected angle, reflex on the projection screen.The image that screen 22 will reflex on it turns to, so that according to the demonstration angle θ in the vertical plane _vGuiding has seen through the image of screen 22, and this shows from 0 to 5 ° at angle, and preferably 3 to 5 °, wherein according to having extreme value tilt angle φ in the vertical plane _vProjected angle, image is reflexed on the screen 22, this angle is from 10 to 30 °, preferably from 15 to 30 °, is preferably at least 15 °.

Can be from three different projected angles, promptly 10 °, 20 ° and 30 ° of test these one side of the present invention.Specifically, make projection light according to given projected angle φ _vReflex to the back side of screen 22, measure the light intensity that sees through screen 22 in different verticals angle of view simultaneously.The result of these tests is illustrated on Fig. 8 with the form of chart.Specifically, Fig. 8 records at the Dian Chu of screen center ± brightness value curve chart in 20 ° of angulars field of view, the percentage of its expression white peak brightness.

Another aspect of the present invention is to adopt a speculum 20, and it is easy to produce the projected angle that comprises the angle of excessively keeping to the side.Fig. 9 has represented in screen 22 horizontal planes by angle γ _hThe speculum 20 of orientation makes projection cathoderay tube 16 be incident upon the image on the speculum 20, to comprise the projected angle φ at the angle of excessively keeping to the side in the horizontal plane _hReflex on the screen 22.The image that screen 22 will reflex on it again turns to, and makes the image that sees through screen 22 by 0 to 5 °, preferably is 3 to 5 ° demonstration angle θ _hOrientation, wherein image is according to the projected angle φ that comprises the angle of excessively keeping to the side _hReflex on the screen 22, this projected angle is 10 to 30 °, preferably is 15 to 30 °, is preferably at least 15 °.

In this one side of the present invention, tested the projected angle φ at four angles of excessively keeping to the side _h, promptly 0 °, 15 °, 30 ° and 45 °.Specifically, make projection light according to given projected angle φ _hReflex to the back side of screen 22, measure simultaneously through the light intensity of screen 22 with as the red green of horizontal view angle function and the inclined to one side intensity of reddish blue.The result of these tests is illustrated in the chart of Figure 10 to 17.Specifically, Figure 10 and 11 is respectively the red green and inclined to one side curve chart of reddish blue that observes at ± 40 ° of horizontal view angle width ranges, with the curve chart that arrives in the inherent screen center of ± 40 ° of horizontal view angle width ranges point observation, wherein φ as the screen intensity of white peak brightness percentage _hThe angle is 0 °.Figure 12 and 13 is respectively the red green and inclined to one side curve chart of reddish blue that observes at ± 40 ° of horizontal view angle width ranges, with the curve chart that arrives in the inherent screen center of ± 40 ° of horizontal view angle width ranges point observation, wherein φ as the screen intensity of white peak brightness percentage _hThe angle is 15 °.Figure 14 and 15 is respectively the red green and inclined to one side curve chart of reddish blue that observes at ± 40 ° of horizontal view angle width ranges, with the curve chart that arrives in the inherent screen center of ± 40 ° of horizontal view angle width ranges point observation, wherein φ as the screen intensity of white peak brightness percentage _hThe angle is 30 °.Figure 16 and 17 is respectively the red green and inclined to one side curve chart of reddish blue that observes at ± 40 ° of horizontal view angle width ranges, with the curve chart that arrives in the inherent screen center of ± 40 ° of horizontal view angle width ranges point observation, wherein φ as the screen intensity of white peak brightness percentage _hThe angle is 45 °.

In another kind of variation the of the present invention, each independently projection cathoderay tube all be furnished with at least one speculum separately, speculum orientation independently wherein is so that each image of reflection together converges to the same point on the screen back side.Figure 18 has represented the preferred embodiment of this variation of the present invention, wherein uses speculum 50,55 and 60 to replace speculum 20.Speculum 50,55 and 60 will be orientated respectively, so that light beam reflects away along the optical axis that converges to screen 22 central points, projection cathoderay tube 14,16 and 18 is finished the projection of image respectively thus.Design of the present invention, especially holographic screen, make the optical axis of speculum 50,55 and 60 can be strictly near with the optical axis of screen 22 quadratures.More precisely, utilize design of the present invention, reflex to image on the screen 22 by speculum 50,55 and 60, can be according to 0 to 30 °, preferably 15 to 30 °, preferably the projected angle φ about 15 ° incides on it.

From the disclosed content of the application, those skilled in the art are readily appreciated that, these and other aspect of the present invention can be used to design and produce the rear projection screen TV that has than imagining the casing that the size that obtains is littler.

In conjunction with previous exemplary embodiment and additional embodiment and disclosed the present invention is clearly for those of ordinary skills.The present invention is not limited to described specific embodiment, and design and the scope identification claimed to the present invention should be as the criterion with appending claims, rather than foregoing data.

Claims (6)

1. projection TV comprises:

Be used for producing respectively a plurality of image projectors (14 of different colours image, 16,18), wherein each image projector has an axis of projection, wherein any two adjacent image projectors limit a pair of image projector, and the axis of projection of every pair of image projector forms an incidence angle;

By two projection screens (22) that stacked holographic element constitutes that are arranged on the substrate (24), the combination of said holographic element and said substrate is stacked on the light-passing board (38), said screen is at the image of first side joint receipts from said projector, and utilize the in check light scattering of the image that shows to show said image in second side, a holographic element in the said holographic element provides the predetermined variation in the vertical range, and another holographic element in the said holographic element provides the predetermined variation in the horizontal extent;

Along projector (14,16,18) at least one speculum (20) that light path is provided with and between the projection screen (22), the orientation of said at least one speculum makes it the image from projector is reflexed on said first side, with respect to said screen quadrature the axle ± 30 ° scope in formation each image a projected angle (φ _hφ _v);

Said projection screen turns to the image that reflexes on it;

Said screen (22) is for all the projected angle (φ in the said scope _hφ _v) all have and be less than or equal to 5 colour cast (C), this colour cast (C) is determined as the maximum that obtains one of at least from following formula:

$C\left(\mathrm{\&theta;}\right)=20\&CenterDot;\mathrm{lo}{g}_{10}\left(\frac{\mathrm{red}\left(\mathrm{\&theta;}\right)}{\mathrm{blue}\left(\mathrm{\&theta;}\right)}\right);$

$C\left(\mathrm{\&theta;}\right)=20\&CenterDot;{\log }_{10}\left(\frac{\mathrm{green}\left(\mathrm{\&theta;}\right)}{\mathrm{blue}\left(\mathrm{\&theta;}\right)}\right)$

Wherein θ is the horizontal view angle, and C (θ) is the colour cast at place, θ angle, and red (θ) is the red brightness value in place, θ angle, and blue (θ) is the blue brightness value in place, θ angle, and green (θ) is the green brightness value in place, θ angle.

2. projection TV as claimed in claim 1, wherein said projected angle scope is 15 ° to 30 ° with respect to said vertical with screen axle, and is-15 ° to-30 ° with respect to said vertical with screen.

3. projection TV as claimed in claim 1, wherein said at least one speculum (20) is in a plurality of image projectors (14,16,18) and between the projection screen (22) be orientated like this, make said axis of projection be in an extreme value tilt angle in 10 ° to the 30 ° scopes, said extreme value tilt angle is the plane being limited by said screen and the formed angle of any said axis of projection of said image projector.

4. projection TV as claimed in claim 1, wherein said at least one speculum (20) is in a plurality of image projectors (14,16,18) and between the projection screen (22) be orientated like this, make said axis of projection be in an extreme value side angle in 10 ° to the 30 ° scopes, said extreme value side angle is the plane being limited by said screen and the formed angle of any said axis of projection of said image projector.

5. projection TV as claimed in claim 1, wherein said at least one speculum (20) comprise at least one speculum independently that is used for each said image projector (14,16,18).

6. projection TV as claimed in claim 1, wherein said screen has following performance index:

Horizontal half angle of view: 38 ° ± 3 °,

Vertical half angle of view: 10 ° ± 1 °,

The screen gain: 〉=8,

Colour cast :≤3.

Images