CN1697524A

CN1697524A - Projection television with holographic screen including stacked elements

Info

Publication number: CN1697524A
Application number: CN 200510069699
Authority: CN
Inventors: 小E·T·哈尔; W·R·普菲勒
Original assignee: RCA Licensing Corp
Current assignee: RCA Licensing Corp
Priority date: 1998-01-29
Filing date: 1998-01-29
Publication date: 2005-11-16

Abstract

TV projection screen possesses a 3D holographic element setup on film base plate. The screen can contain multiple contraposed holographic elements and/or Fresnel lenses, which possess variable optical characters along vertical and horizontal directions, such as variable gain of holographic element reaches to plus and minus 40 degree in horizontal visual angle, and plus and minus 20 degree in vertical visual angle. One light path of at least one projection tube forms a convergence angle alpha with a straight line or axis perpendicular to screen. Thus, holographic elements form an interference pattern so as to reduce color deflection on display image compared with color deflection caused by offset axis protection in other cases. When the said angle alpha is about between 0 degree to 30 degree, color deflection is smaller than and about equal to 5 on screen.

Description

Projection television with holographic screen including stacked elements

发明领域Field of Invention

一般来说，本发明涉及投影电视接收机领域，具体地说，本发明涉及具有能够明显减小色偏和/或减小机壳深度的显示屏的一种投影电视接收机。The present invention relates generally to the field of projection television receivers, and more particularly, the present invention relates to a projection television receiver having a display screen with substantially reduced color shift and/or reduced cabinet depth.

背景技术 Background technique

色偏被定义为：在垂直视角的最大亮度位置测得的、由红色、绿色、和蓝色投影管发出的投射图象在投影屏幕中心处形成的白图象的红色/蓝色或绿色/蓝色比例在不同的水平视角的变化。Color shift is defined as the red/blue or green/green color shift of the white image formed by the projected images from the red, green, and blue projection tubes at the center of the projection screen, measured at the maximum brightness position of the vertical viewing angle. The blue scale changes at different horizontal viewing angles.

色偏问题是由于不同颜色(如红，蓝和绿色)图象需要至少三个图象投影器而引起的。投影屏幕在第一侧接收来自至少三个投影器的图象，并在第二侧通过控制所有显示图象的光色散而显示这些图象。通常为绿色，并且通常位于投影器阵列中心的一个投影器具有基本正交于屏幕取向的第一光路。通常为红色和蓝色，且通常位于阵列中心绿色投影器相对两侧的至少两个投影器，分别具有以非正交取向的入射角向第一光路会聚的光路。红、蓝投影器相对于屏幕和绿投影器的非正交关系导致了色偏。由于色偏，在屏幕上各个位置的色调可能不相同。色调差别大的状态通常被称为白色均匀度较差。色偏越小白色均匀度越好。The color shift problem is caused by requiring at least three image projectors for images of different colors (eg red, blue and green). A projection screen receives images from at least three projectors on a first side and displays these images on a second side by controlling light dispersion of all displayed images. One projector, which is generally green in color and generally located in the center of the array of projectors, has a first light path oriented substantially normal to the screen. At least two projectors, typically red and blue, and typically located on opposite sides of the central green projector of the array, each have optical paths that converge toward the first optical path at non-orthogonal oriented angles of incidence. The non-orthogonal relationship of the red and blue projectors to the screen and the green projector causes a color shift. Due to color cast, the color tone may not be the same at various locations on the screen. A state where the difference in color tone is large is generally referred to as poor white uniformity. The smaller the color cast, the better the white uniformity.

用数码标注色偏，其中较低的数值表示较小的色偏和较好的白色均匀度。根据通行的规程，从各个水平视角测量屏幕中心的红、绿、蓝亮度值，通常从至少大约-40°至+40°，到大约-60°至+60°的范围，并以5°或10°为递增间隔。正负角度分别代表屏幕中心右侧和左侧的水平视角。这些测量值是在峰值垂直视角处获得的。在0°处归一化红、绿、蓝的数据。在每个角度处用下述一或两个方程(I)和(II)进行评价：Color casts are indicated numerically, where lower numbers indicate less color cast and better white uniformity. According to accepted practice, the red, green, and blue luminance values at the center of the screen are measured from various horizontal viewing angles, usually ranging from at least approximately -40° to +40°, to approximately -60° to +60°, and scaled by 10° is the incremental interval. Positive and negative angles represent horizontal viewing angles to the right and left of screen center, respectively. These measurements are taken at the peak vertical viewing angle. Red, green, and blue data were normalized at 0°. Evaluate at each angle using one or both of the following equations (I) and (II):

$C C ((θ θ)) = = 2020 \cdot \cdot lo lo {g g}_{1010} ((\frac{red red ((θ θ))}{blue blue ((θ θ))})) - - - - - - ((I I))$

$C C ((θ θ)) = = 2020 \cdot \cdot l l {og og}_{1010} ((\frac{green green ((θ θ))}{blue blue ((θ θ))})) - - - - - - ((II II))$

其中θ是水平视角范围内的任意角度，C(θ)是θ角处的色偏，red(θ)是θ角处红色的亮度值，blue(θ)是θ角处蓝色的亮度值，而green(θ)是θ角处绿色的亮度值。这些值的最大值是屏幕的色偏。Where θ is any angle within the range of the horizontal viewing angle, C(θ) is the color shift at the θ angle, red(θ) is the brightness value of red at the θ angle, and blue(θ) is the blue brightness value at the θ angle, And green(θ) is the brightness value of green at angle θ. The maximum of these values is the color cast of the screen.

通常，色偏不应当大于5这个商业上可接受的标定屏幕设计值。其他工程和设计约束条件可能有时需要色偏比5大一些，尽管这样的色偏性能是不希望有的，并常常导致观看效果低劣的白色均匀度较差的图象。Generally, the color shift should not be greater than 5, which is a commercially acceptable nominal screen design value. Other engineering and design constraints may sometimes require a color shift larger than 5, although such color shift performance is undesirable and often results in poorly viewed images with poor white uniformity.

投影电视接收机的投影屏幕通常是采用挤压法利用一或多个有图案的轧辊形成热塑性板材表面的形状而制造的。其构造一般为双凸透镜元件阵列，也称为小透镜阵列。这些双凸透镜元件可以形成在相同板状材料的一侧或两侧；或者仅形成在不同板的一侧上，再将这些不同的板永久地结合成一个叠层单元，或采用其它方式彼此相邻地安装而使其具有叠层单元的功能。在许多的设计中，屏幕的一个表面构成一个菲涅尔透镜形成光散射。现有技术减小色偏和改进白色均匀度的尝试仅仅集中在屏幕的两个方面。一个方面是双凸透镜元件的形状和布局。另一个方面是屏幕材料、或其中某些部分为控制光散射而掺杂光散射颗粒的程度。这些尝试的例子见下列专利文献。Projection screens for projection television receivers are typically manufactured by extrusion using one or more patterned rolls to shape the surface of a thermoplastic sheet. Its configuration is generally an array of lenticular lens elements, also known as a lenslet array. These lenticular elements can be formed on one or both sides of the same sheet material; or on only one side of different sheets that are permanently bonded into a laminated unit, or otherwise connected to each other. It is installed adjacently so that it has the function of a laminated unit. In many designs, one surface of the screen forms a Fresnel lens to diffuse light. Prior art attempts to reduce color shift and improve white uniformity have focused on only two aspects of the screen. One aspect is the shape and layout of the lenticular elements. Another aspect is the extent to which the screen material, or portions thereof, are doped with light scattering particles to control light scattering. Examples of these attempts are found in the following patent documents.

在美国专利US.4,432,010和US.4,536,056中，投影屏幕包括一个具有输入表面和出射表面的透光凸透镜板。输入表面的特点表现在水平散射的凸透镜轮廓方面，其凸透镜深度Xv与近轴曲率半径R1的比值(Xv/R1)在0.5到1.8范围内。该轮廓沿着光轴方向延伸，且形成许多非球面输入凸透镜。In US Pat. Nos. 4,432,010 and 4,536,056, the projection screen comprises a light transmissive lenticular panel having an input surface and an output surface. The input surface is characterized by a horizontally scattering convex lens profile with a ratio of the convex lens depth Xv to the paraxial radius of curvature R1 (Xv/R1) in the range of 0.5 to 1.8. The profile extends along the optical axis and forms a number of aspheric input convex lenses.

通常采用的是双侧具有凸透镜的屏幕。这种屏幕在其输入表面上具有柱面输入凸透镜元件，和形成在该屏幕输出表面侧的柱面凸透镜元件，以及形成在输出表面上不会聚光部分的光吸收层。输入和输出凸透镜元件都是圆形，椭圆形或双曲线形的，并由下列方程(TTT)表示：Usually, a screen with convex lenses on both sides is used. This screen has cylindrical input lenticular lens elements on its input surface, cylindrical lenticular lens elements formed on the output surface side of the screen, and a light absorbing layer formed on the output surface at a portion that does not condense light. Both the input and output lenticular elements are circular, elliptical or hyperbolic and are represented by the following equation (TTT):

$Z Z ((x x)) = = \frac{{Cx Cx}^{22}}{11 + + {[[11 - - ((K K + + 11)) {C C}^{22} {x x}^{22}]]}^{\frac{11}{22}}} - - - - - - ((III III))$

其中C是主曲率，而K是圆锥曲线的常数。where C is the principal curvature and K is the conic constant.

此外，透镜还可以具有其中添加了高于二次项的曲线。In addition, lenses may also have curves to which higher than quadratic terms are added.

在用这种双侧凸透镜构成的屏幕中，已经提出指定了输入透镜与输出透镜或构成这些透镜的凸透镜元件之间的位置关系。例如，美国专利US.4,443,814所教导的，按这样的方式确定输入透镜与输出透镜的位置：一个透镜的透镜表面在另一个透镜的焦点处。日本专利JP.58-59436也教导：输入透镜的偏心率基本等于构成凸透镜的材料折射率的倒数。美国专利US.4,502,755还教导，按以下方式组合出两个双侧有凸透镜的板：各凸透镜的光轴平面彼此互成直角，并按如下方式形成这种双侧凸透镜：在透镜外围的输入透镜和输出透镜关于光轴是不对称的。美国专利US.4,953,948还教导，只有输入透镜凹谷处的光会聚位置应该偏向输出透镜观看一侧的表面，以使光轴失准的公差和厚度差可以较大，或使色偏可以较小。In screens constructed with such double-sided convex lenses, it has been proposed to specify the positional relationship between input lenses and output lenses or convex lens elements constituting these lenses. For example, US Pat. No. 4,443,814 teaches positioning the input and output lenses in such a way that the lens surface of one lens is at the focal point of the other lens. Japanese Patent JP.58-59436 also teaches that the eccentricity of the input lens is substantially equal to the reciprocal of the refractive index of the material constituting the convex lens. U.S. Patent No. 4,502,755 also teaches to combine two plates with convex lenses on both sides in such a way that the optical axis planes of the convex lenses are at right angles to each other and to form such convex lenses on both sides as follows: the input lens at the periphery of the lens and the output lens are asymmetric about the optical axis. U.S. Patent No. 4,953,948 also teaches that only the light converging position at the valley of the input lens should be biased towards the surface on the viewing side of the output lens, so that the tolerance of optical axis misalignment and thickness difference can be large, or the color shift can be small .

除了这些减小色偏或白色不均匀性的各种方案之外，其他改进投影屏幕性能的方案是针对提高图象亮度，和在水平和垂直方向确保适当视场的。这些方案的要点可以从美国专利US.5,196,960找到，该文献教导了一种双侧凸透镜板，它包括具有输入透镜的输入透镜层和具有输出透镜且其透镜表面形成在输入透镜光会聚点和其附近的输出透镜层，其中输入透镜层和输出透镜层均由基本透明的热塑性树脂构成，且至少输出层包括光散射微粒，而且输入透镜层和输出透镜层之间的光散射特性存在着差别。输入透镜组是一种柱透镜。输出透镜由一组输出透镜层构成，其每一层都有一个透镜表面位于输入透镜层各透镜光会聚点所在的面或其附近。光吸收层形成在输出透镜层不会聚光的部分。这种屏幕设计提供了很好的水平视角，较小的色偏和较亮的画面，并且易于用挤压法制造。In addition to these various schemes for reducing color shift or white non-uniformity, other schemes for improving the performance of projection screens are aimed at increasing image brightness, and ensuring proper field of view both horizontally and vertically. The gist of these solutions can be found in U.S. Patent No. 5,196,960, which teaches a double-sided convex lens sheet comprising an input lens layer with input lenses and an output lens with lens surfaces formed between the input lens light convergence point and its The adjacent output lens layer, wherein both the input lens layer and the output lens layer are composed of a substantially transparent thermoplastic resin, and at least the output layer includes light scattering particles, and there is a difference in light scattering properties between the input lens layer and the output lens layer. The input lens group is a cylindrical lens. The output lens is composed of a group of output lens layers, each of which has a lens surface located at or near the surface where the light converging points of the lenses of the input lens layer are located. The light absorbing layer is formed at a portion where the output lens layer does not collect light. This screen design offers good horizontal viewing angles, less color cast and a brighter picture, and is easy to manufacture with extrusion.

尽管在投影屏幕设计中改进研究已有许多年，但是仍然不断发现需要改进之处。而且，还没有成功地超过某些基准。图象投影器的几何尺寸限定的入射角度，本文中称为α角，一般限定为大于0°且小于或等于约10°或11°。图象投影器的尺寸使α角基本不可能接近0°。在小于约10°或11°的α角范围内，如根据等式(I)和(II)所确定的，已经实现的最佳色偏性能在5左右。在大于约10°或11°的α角范围内，已经实现的最佳色偏性能没有商业价值。事实上，具有在大于约10°或11°α角的投影电视接收机还未在市场上出现。Although there have been many years of research into improvements in projection screen design, areas for improvement are continually being discovered. Also, some benchmarks have not been successfully exceeded. The geometry of the image projector defines the angle of incidence, referred to herein as angle alpha, generally defined as greater than 0° and less than or equal to about 10° or 11°. The size of the image projector makes it virtually impossible for the angle α to approach 0°. In the range of α angles less than about 10° or 11°, the best color shift performance has been achieved around 5, as determined from equations (I) and (II). In the alpha angle range greater than about 10° or 11°, the best color shift performance that has been achieved has no commercial value. In fact, projection television receivers having an alpha angle greater than about 10° or 11° have not yet appeared on the market.

小α角有一个明显且不希望的后果，即必须有很大的机壳深度来容纳投影电视接收机。大的深度是需要容纳具有小入射角(α)光路的直接结果。对于给定尺寸的图象投影器和光学元件而言，仅仅可以通过增加图象投影器或其光学件与屏幕之间的光路长度来减小入射角度。减小投影电视机壳尺寸的技术，一般取决于用于折叠长光路的多个反射镜的布置。减小色偏的这些努力最终由于可能的入射角度范围小而受到限制。An obvious and undesired consequence of the small alpha angle is that a large cabinet depth must be provided to accommodate the projection television receiver. The large depth is a direct result of the need to accommodate light paths with small angles of incidence (α). For a given size of image projector and optics, the angle of incidence can only be reduced by increasing the optical path length between the image projector or its optics and the screen. Techniques for reducing the size of projection television cabinets generally depend on the arrangement of multiple mirrors used to fold long optical paths. These efforts to reduce color shift are ultimately limited by the small range of possible angles of incidence.

宝丽来公司出售一种标牌为DMP-128^光致聚合物，宝丽来公司可以用专有的方法将其制成三维全息元件。US.5,576,853描述了该全息摄影制造方法的一部分。全息光致聚合物通常用于借助将相干光分解成照明光和基准光来记录全息图象。照明光照射在拍摄对象上。从被摄物反射的光束和从被摄物旁边经过的基准光束照射在光致聚合物媒质上，该媒质包含可显影的光敏摄影组合物。两光束的光波相互干涉，即它们通过构造和重构的干涉，产生出驻波图案，该图案具有对局部摄影组合物曝光的正弦波峰，和不对局部组合物进行曝光的零点。在摄影媒质显影时，相应的干涉图案就被记录在媒质中。用相干基准光照射该媒质，被摄物的图象被再现出来，并且可以在其视角范围内观看到。The Polaroid Corporation sells a photopolymer under the designation DMP-128 ^(R) that can be fabricated into three-dimensional holographic elements by a proprietary process. US Pat. No. 5,576,853 describes part of this holographic manufacturing method. Holographic photopolymers are commonly used to record holographic images by splitting coherent light into illumination and reference light. The illumination light shines on the subject. The beam reflected from the subject and the reference beam passing by the subject impinge on a photopolymer medium comprising a developable photosensitive photographic composition. The light waves of the two beams interfere with each other, ie they interfere by construction and reconstruction, producing a standing wave pattern with sinusoidal peaks that expose the partial photographic composition, and zeros that do not expose the partial composition. When the photographic medium is developed, a corresponding interference pattern is recorded in the medium. By illuminating the medium with coherent reference light, the image of the subject is reproduced and can be viewed within its viewing angle.

由于从被摄物上所有被照明点发出的光与全息图上所有点的基准光相互干涉，所以代表普通全息被摄物的全息图所记录的干涉图案很复杂。通过记录空白被摄物(通过两个基准光束的有效干涉)应该能够产生一空白全息图，其中的干涉图案更为规则。在此情况下，干涉图案与衍射光栅相似，但衍射光栅的间距或分辨率与形成有更大尺寸凸透镜单元以便从后面的投影器沿特定方向弯折或折射光线的投影屏幕相比细得多。Since the light emitted from all the illuminated points on the object interferes with the reference light at all points on the hologram, the interference pattern recorded by the hologram representing a common holographic object is very complicated. By recording a blank subject (by effective interference of the two reference beams) it should be possible to generate a blank hologram in which the interference pattern is more regular. In this case, the interference pattern is similar to a diffraction grating, but the pitch or resolution of the diffraction grating is much finer than that of a projection screen formed with larger sized convex lens elements to bend or refract light rays in a specific direction from the projector behind .

在为建立DMP-128^光致聚合物全息产品市场的所做努力中，作为多种建议的一种，宝丽来公司提出了投影电视三维全息屏。该建议是基于宝丽来公司所希望的高亮度高分辨率，低制造成本，低重量，和装运过程中避免受到双片屏幕所受磨损的优点而提出的。宝丽来公司从未提出过任何可制成这种全息投影电视屏幕体全息图的具体全息结构，也从未考虑过全息或其它任何类型投影电视屏幕的色偏问题。In an effort to establish a market for DMP-128 ^(R) photopolymer holographic products, the Polaroid Corporation proposed a three-dimensional holographic screen for projection television as one of several proposals. The proposal is based on Polaroid's desired advantages of high brightness and high resolution, low manufacturing cost, low weight, and avoiding the wear and tear of the two-piece screen during shipping. Polaroid has never proposed any specific holographic structure that would make such a volume hologram for such a holographic projection TV screen, nor has it ever considered the problem of color shift in holographic or any other type of projection TV screen.

总之，尽管多年来进行了很多的开发研究，以提供具有小于5，甚至大大小于5的色偏，或具有低至5的色偏而α角大于10°或11°的屏幕的投影电视接收机，但是与传统投影屏幕凸透镜元件形状位置和散射体的不断变化出新不同，在解决色偏问题方面没有进展。而且，尽管建议了三维全息元件可以用于投影屏幕，但由于没有涉及色偏问题，也就不曾在提供有三维全息屏的投影电视方面作过尝试。因此，长期以来对一种具有大大改善色偏性能并且可以被装入一个更小机壳内的投影电视接收机的需求，还没有得到满足。In conclusion, although much development work has been done over the years to provide projection television receivers with screens with a color shift of less than 5, or even much less than 5, or with a color shift as low as 5 with an alpha angle greater than 10° or 11° , but unlike traditional projection screens with constant changes in the shape and location of convex lens elements and diffusers, there has been no progress in solving the problem of color shift. Furthermore, although it has been suggested that a three-dimensional holographic element could be used in a projection screen, no attempt has been made to provide a projection television with a three-dimensional holographic screen since no color shift is involved. Accordingly, there is a long felt need for a projection television receiver having greatly improved color shift performance and which can be packed into a smaller enclosure.

发明概要Summary of Invention

根据本文所教导的发明方案的投影电视接收机明显改善了色偏性能(按幅值量级测量)，使得入射角α在小于10°或11°范围内的投影电视接收机可以达到2或更小的色偏。而且，该色偏性能显然可以提供符合商业要求的装于很小机壳内且入射角高达30°的投影电视接收机。这种大α角接收机的色偏性能至少与传统的小α角接收机(例如等于5的色偏)一样好，而在小α角接收机的情况下有望接近或达到低至大约2的值。Projection television receivers according to the inventive arrangements taught herein have significantly improved color shift performance (measured in magnitude) such that projection television receivers with angles of incidence α in the range of less than 10° or 11° can achieve 2 or more Small color cast. Furthermore, the color shift performance clearly provides commercially desirable projection television receivers with angles of incidence as high as 30 DEG in a very small enclosure. The color shift performance of such large-α angle receivers is at least as good as that of conventional small-α-angle receivers (e.g., a color shift equal to 5), while in the case of small-α angle receivers it is expected to approach or reach as low as about 2 value.

这些效果是由完全放弃挤压透镜屏幕技术而获得的。相反，根据本发明方案的投影电视接收机，具有由形成在基板上，如Mylar等聚乙烯膜上的三维全息元件构成的屏幕。These effects are obtained by completely abandoning squeeze lenticular screen technology. In contrast, a projection television receiver according to the inventive concept has a screen consisting of three-dimensional holographic elements formed on a substrate, such as a polyethylene film such as Mylar(R).

最初开发这种三维全息屏幕，是因为它具有在高亮度、高分辨率、低制造成本、低质量和在装运等过程中抗两片屏幕相互磨损方面的突出优点。在检测该三维屏幕的光学特性是否至少与传统屏幕一样好时，发现了该三维全息屏幕的色偏。按照方程(I)和(II)所得到的三维全息屏幕色偏性能出乎意料地低。限制现有技术改进提高的障碍已经完全消除。而且现在可以开发出具有更大入射角α的投影结构的更小机壳。This three-dimensional holographic screen was originally developed because of its outstanding advantages in high brightness, high resolution, low manufacturing cost, low quality, and resistance to mutual abrasion of two screens during shipment, etc. A color shift of the 3D holographic screen was found when testing whether the optical properties of the 3D screen were at least as good as conventional screens. The color shift performance of the three-dimensional holographic screen obtained according to equations (I) and (II) is unexpectedly low. The barriers limiting the improvement of existing technologies have been completely removed. Furthermore, it is now possible to develop smaller housings for projection structures with larger angles of incidence α.

根据本文所教导的本发明方案，具有非凡特性三维全息屏幕的投影电视包括：至少三个不同颜色图象的投影器；由布置在基板上三维全息元件构成的投影屏幕，该屏幕在第一侧接收来自投影器的图象，并在第二侧显示该图象且同时控制所显示图象的光散射；投影器之一具有基本与屏幕正交取向的第一光路，而至少两个投影器分别具有在非正交倾斜入射角内向第一光路会聚的光路；以及代表具有用于有效减小显示图象色偏结构的凸透镜三维阵列的三维干涉阵列或衍射阵列，该屏幕在大于零且小于或近似等于30度入射角范围内具有小于或等于约5的色偏，如至少下式之一所获得的最大值确定的那样：According to the inventive solution taught herein, a projection television having a three-dimensional holographic screen with extraordinary properties comprises: projectors for at least three images of different colors; a projection screen composed of three-dimensional holographic elements arranged on a substrate, the screen being on a first receiving an image from a projector and displaying the image on a second side while controlling light scattering of the displayed image; one of the projectors has a first optical path oriented substantially orthogonal to the screen, and at least two of the projectors Respectively have the light paths converging to the first light path in the non-orthogonal oblique incident angle; or approximately equal to a range of incident angles of approximately 30 degrees having a color shift of less than or equal to about 5, as determined by the maximum value obtained by at least one of the following equations:

$C C ((θ θ)) = = 2020 . . lo lo {g g}_{1010} ((\frac{red red ((θ θ))}{blue blue ((θ θ))}));;$

$C C ((θ θ)) = = 2020 \cdot \cdot lo lo {g g}_{1010} ((\frac{green green ((θ θ))}{blue blue ((θ θ))}))$

其中θ是水平视角范围内的任意角度，C(θ)是θ角处的色偏，red(θ)是θ角处红色的亮度值，blue(θ)是θ角处蓝色的亮度值，而green(θ)是θ角处绿色的亮度值。可以预期屏幕的色偏小于5，例如小于或等于4，3或甚至2。Where θ is any angle within the range of the horizontal viewing angle, C(θ) is the color shift at the θ angle, red(θ) is the brightness value of red at the θ angle, and blue(θ) is the blue brightness value at the θ angle, And green(θ) is the brightness value of green at angle θ. Screens can be expected to have a color shift of less than 5, such as less than or equal to 4, 3 or even 2.

就已知的10°或11°左右入射角处障碍而言，在大于0°和小于或等于10°左右的入射角第一子范围内，屏幕的色偏在所有入射角度都小于或等于2左右；而在大于10°左右和小于或等于30°左右的入射角第二子范围内，屏幕的色偏在所有入射角度都小于或等于5左右。As far as the known obstacle at an incident angle of about 10° or 11° is concerned, in the first sub-range of incident angles greater than 0° and less than or equal to about 10°, the color shift of the screen is less than or equal to about 2 at all incident angles ; and in the second sub-range of incident angles greater than about 10° and less than or equal to about 30°, the color shift of the screen is less than or equal to about 5 at all incident angles.

该屏幕还包括一个透光的加强部件，如用厚度在2-4mm左右范围内的一层丙烯酸材料构成的。基板包括长寿命透明防水膜，如聚对苯二甲酸乙二醇酯树脂薄膜。该基板可以是厚度约在1-10密耳范围内的薄膜。已经发现7密耳左右的厚度足以支撑三维全息元件。薄膜的厚度与性能无关。三维全息元件具有不大于约20微米范围内的厚度。投影电视还可以包括一个或多个位于图象投影器与屏幕之间的反射镜。The screen also includes a light transmissive reinforcing member, eg formed of a layer of acrylic material having a thickness in the range of about 2-4mm. The substrate includes a long-life transparent waterproof film such as a polyethylene terephthalate resin film. The substrate can be a thin film having a thickness in the range of about 1-10 mils. A thickness of around 7 mils has been found to be sufficient to support a three-dimensional holographic element. The thickness of the film has nothing to do with performance. The three-dimensional holographic element has a thickness in the range of not greater than about 20 microns. Projection televisions may also include one or more mirrors positioned between the image projector and the screen.

根据本发明的一个方面，通过将一组全息屏幕元件和/或准直元件层叠设置可以进一步提高投影屏幕的色偏性能。例如，在全息屏幕的背后可以设置垂直和水平的线性菲涅尔透镜以在垂直或水平视角范围内实现光传输特性的所需变化。此外，也可以将具有在视角范围内光传输特性变化的一组全息屏幕元件层叠设置。根据一个实际的实施例，至少层叠两个全息元件，一个用于在垂直范围内产生预定变化，另一个用于在水平范围内产生预定变化。按照这种方式，可以调节在有用视角范围内图像的亮度，并使之达到最佳以充分利用可得到的全部照度。此外，由于能够以低于圆形变化元件的成本制造直线型变化元件，所以将全息元件和/或准直元件层叠设置能够以可接受的成本满足多种性能指标。例如，可以以只有圆形菲涅尔透镜成本25％的低成本，利用压印或轧辊挤压方法制造直线型变化菲涅尔元件。类似地，直线型变化全息母版也比限定两维变化的圆形母版更为简单和成本低廉。According to one aspect of the present invention, the color shift performance of the projection screen can be further improved by stacking a group of holographic screen elements and/or collimation elements. For example, vertical and horizontal linear Fresnel lenses can be placed behind a holographic screen to achieve desired changes in light transmission characteristics over a range of vertical or horizontal viewing angles. In addition, a group of holographic screen elements that have light transmission characteristics that vary within the range of viewing angles can also be stacked. According to a practical embodiment, at least two holographic elements are stacked, one for producing a predetermined change in the vertical range and the other for producing a predetermined change in the horizontal range. In this way, the brightness of the image can be adjusted and optimized to take full advantage of the full available illuminance over the range of useful viewing angles. In addition, since the linear variable element can be manufactured at a lower cost than the circular variable element, the stacked arrangement of the holographic element and/or the collimator element can meet various performance indicators at an acceptable cost. For example, linear varying Fresnel elements can be manufactured by embossing or roll extrusion at a cost that is only 25% of the cost of a circular Fresnel lens. Similarly, a linearly varying holographic master is simpler and less expensive than a circular master that defines two-dimensional variation.

附图说明Description of drawings

图1是表示根据本文教导的本发明方案的投影电视示意图。BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of a projection television in accordance with the inventive arrangements taught herein.

图2是解释本发明方案所用投影电视结构的简化示意图。Figure 2 is a simplified schematic diagram of the structure of a projection television used to explain the inventive arrangement.

图3是根据本发明方案加强的投影屏幕侧视图。Figure 3 is a side view of a projection screen reinforced in accordance with an embodiment of the present invention.

图4是投影屏幕另一实施例的示意图，所说屏幕具有两个分别在水平和垂直视角范围内有增益变化的重叠的全息元件。Figure 4 is a schematic diagram of another embodiment of a projection screen having two overlapping holographic elements with varying gain over horizontal and vertical viewing angles, respectively.

图5是表示水平变化的全息元件垂直叠置着或不叠置着垂直变化的全息元件时，作为水平视角函数的白色峰值亮度比的曲线图。Figure 5 is a graph showing the white peak luminance ratio as a function of horizontal viewing angle for horizontally varying holographic elements with and without vertically stacked vertically varying holographic elements.

图6是具有叠置全息元件和准直屏幕层的另一个实施例的示意图。Figure 6 is a schematic diagram of another embodiment with stacked holographic elements and collimating screen layers.

对优选实施例的说明Description of the preferred embodiment

图1示意性表示一个投影电视接收机10。排成阵列12的投影阴极射线管14、16和18分别产生红色，绿色和蓝色的图象。这些阴极射线管还配置有各自的透镜15、17和19。投射出去的图象被反射镜20反射到投影屏幕22上。还可以根据光路的具体结构，采用附加反射镜。绿色阴极射线管16沿着光路32投射绿色图象，该光路基本正交于屏幕取向。换句话说，光路的中心线与屏幕成直角。红色和蓝色阴极射线管分别具有光路34和36，这两个光路非正交取向地以入射角α向第一光路32会聚。这个入射角引发了色偏的问题。FIG. 1 schematically shows a projection television receiver 10 . Projection cathode ray tubes 14, 16 and 18 arranged in array 12 produce red, green and blue images, respectively. These cathode ray tubes are also provided with respective lenses 15 , 17 and 19 . The projected image is reflected by the mirror 20 onto the projection screen 22 . Additional mirrors can also be used according to the specific structure of the optical path. Green cathode ray tube 16 projects a green image along optical path 32, which is oriented substantially normal to the screen. In other words, the centerline of the light path is at right angles to the screen. The red and blue cathode ray tubes have optical paths 34 and 36, respectively, which converge toward the first optical path 32 at an angle of incidence a in a non-orthogonal orientation. This angle of incidence causes the problem of color shift.

屏幕22包括布置在基板24上的三维全息元件26。全息元件26是形成有衍射图案的全息图母版印片，该全息图案可以调配三个投影器14、16和18输出光能的分布，并可以使其在屏幕高度和/或宽度方向上发生改变。在一个优选的方案中，全息图是中心型全息图，它使入射光重新取向。该屏幕在第一输入表面一侧28接收来自投影器的图象，并在第二输出表面侧30显示该图象，并控制所有显示图象的光散射。可取的是，基板为长寿命透明防水膜，如聚对苯二甲酸乙二醇酯树脂薄膜。这类膜的一种是可以从E.I.du Pont de Nemours&Co.公司得到的Mylar^牌产品。该薄膜基板具有1-10密耳范围内的厚度，等于0.001-0.01英寸或25.4-254微米。已经发现，7密耳左右厚度的薄膜足以支撑三维全息元件。薄膜的厚度一般与屏幕的性能无关，尤其是色偏性能，所用可采用不同的膜厚度。三维全息元件26具有不大于约20微米范围内的厚度。The screen 22 includes a three-dimensional holographic element 26 arranged on a substrate 24 . Holographic element 26 is a holographic master print formed with a diffractive pattern that modulates the distribution of light energy output by the three projectors 14, 16 and 18 and causes it to occur in the height and/or width direction of the screen. Change. In a preferred aspect, the hologram is a central hologram which reorients incident light. The screen receives the image from the projector on the first input surface side 28, displays the image on the second output surface side 30, and controls light scattering of all displayed images. Preferably, the substrate is a long-life transparent waterproof film, such as a polyethylene terephthalate resin film. One such film is the Mylar ^(R) brand product available from EI du Pont de Nemours & Co. Company. The film substrate has a thickness in the range of 1-10 mils, equal to 0.001-0.01 inches or 25.4-254 microns. It has been found that a film thickness of around 7 mils is sufficient to support a three-dimensional holographic element. The thickness of the film is generally irrelevant to the performance of the screen, especially the color shift performance, and different film thicknesses can be used. Three-dimensional holographic element 26 has a thickness in the range of not greater than about 20 microns.

三维全息屏至少可以从两个来源获得。宝丽来公司利用有专有权的湿式化学方法将它的DMP-128^光致聚合物材料制成三维全息元件。该方法包括：在光致聚合物上形成衍射全息元件，该全息元件可以包含水平和/或垂直视角范围内的屏幕增益变化。用相干光对光致聚合物全息介质进行曝光可以制备出全息母版，该相干光包含基准光束，和从具有与所需增益变化对应的明暗变化平面图案上反射出来光束。3D holographic screens are available from at least two sources. Polaroid Corporation utilizes a proprietary wet chemical process to form three-dimensional holographic elements from its DMP-128 ^(R) photopolymer material. The method includes forming a diffractive holographic element on a photopolymer, which holographic element may contain variations in screen gain over a range of horizontal and/or vertical viewing angles. A holographic master can be prepared by exposing a photopolymer holographic medium to coherent light comprising a reference beam and beams reflected from a planar pattern with light and dark changes corresponding to the desired gain change.

用于上述和本申请权利要求书提出的投影电视接收机中的三维全息屏，其优选实施例是宝丽来公司利用有专有权的湿式化学方法按照下述性能指标制成的：The preferred embodiment of the three-dimensional holographic screen used in the projection television receiver set forth above and in the claims of this application is made by Polaroid Corporation using a proprietary wet chemical method according to the following performance indicators:

水平半视角：38°±3°，Horizontal half viewing angle: 38°±3°,

垂直半视角：10°±1°，Vertical half viewing angle: 10°±1°,

屏幕增益：≥8，Screen gain: ≥8,

色偏：≤3，Color shift: ≤3,

其中水平和垂直视角是按照传统方法测得的，屏幕增益是正交于屏幕进行测量时，从光源射向观看表面后面的光强与从观看表面前面射向观看者的光强相除的商，而色偏按上述的方法测量。如发明概述中所说的，三维全息投影屏幕优异的色偏性能是完全出乎意料的。where the horizontal and vertical viewing angles are measured according to traditional methods, and the screen gain is the quotient of dividing the light intensity from the light source to the back of the viewing surface by the light intensity from the front of the viewing surface to the viewer when measured perpendicular to the screen , and the color shift is measured as described above. As stated in the Summary of the Invention, the excellent color shift performance of the 3D holographic projection screen is completely unexpected.

图2是投影电视的简化示意图，其中为了解释色偏性能省略了反射镜和透镜。红色和蓝色阴极射线管14和18的光轴34和36，是相对于绿色阴极射线管16的光轴32以入射角α对称取向的。机壳的最小深度D由屏幕22与阴极射线管后缘之间的距离确定。应当理解，α角越小，阴极射线管彼此越靠近，且还必须与屏幕隔开以使之与各个射线管之间留有间隙。当α角足够小时，这种干扰是不可避免的。这将不得不增大机壳的最小深度D。相反地，α角越大，阴极射线管可以更为靠近屏幕22，从而减小机壳的最小深度D。Figure 2 is a simplified schematic diagram of a projection television with mirrors and lenses omitted to explain color shift performance. The optical axes 34 and 36 of the red and blue cathode ray tubes 14 and 18 are oriented symmetrically with respect to the optical axis 32 of the green cathode ray tube 16 at an angle of incidence a. The minimum depth D of the cabinet is determined by the distance between the screen 22 and the rear edge of the cathode ray tube. It will be appreciated that the smaller the angle α, the closer the cathode ray tubes are to each other and must also be spaced from the screen to leave a gap between each tube. This interference is unavoidable when the α angle is small enough. This would have to increase the minimum depth D of the enclosure. Conversely, the larger the angle α, the closer the CRT can be to the screen 22, thereby reducing the minimum depth D of the cabinet.

在屏幕22的观看一侧，两个水平半视场角用-β和+β表示。和在一起后的总水平视场角为2β。该半视场角通常可以在±40°至±60°的范围内。在每个半角内是一组特定角度θ，在其中可以测量色偏，并根据上述等式(I)和(II)加以确定。On the viewing side of the screen 22, the two horizontal half angles of view are denoted by -β and +β. Together, the total horizontal field of view is 2β. The half angle of view may generally be in the range of ±40° to ±60°. Within each half-angle is a set of specific angles θ at which color shift can be measured and determined according to equations (I) and (II) above.

就已知的10°或11°左右入射角处的障碍而言，在大于0°和小于或等于10°左右的入射角第一子范围内，三维全息屏幕的色偏在所有角度都小于或等于2左右；而在大于10°左右和小于或等于30°左右的入射角第二子范围内，屏幕的色偏在所有角度都小于或等于5左右。可以料想，第一子范围中小于或等于2左右的色偏也可以在更大入射角的第二子范围内实现。As far as the obstacles at the known incident angles of around 10° or 11° are concerned, in the first sub-range of incident angles greater than 0° and less than or equal to around 10°, the color shift of the three-dimensional holographic screen is less than or equal to at all angles 2; while in the second sub-range of incident angles greater than about 10° and less than or equal to about 30°, the color shift of the screen is less than or equal to about 5 at all angles. It is conceivable that a color shift of less than or equal to around 2 in the first sub-range can also be achieved in the second sub-range of larger incident angles.

参考图3，基板24包括一个透明膜，如上所述的Mylar。形成三维全息元件26的光致聚合物材料被放在膜层24上。适合的光致聚合物材料是DMP-128。Referring to FIG. 3, substrate 24 comprises a transparent film, Mylar(R) as described above. A photopolymer material forming three-dimensional holographic element 26 is placed on film layer 24 . A suitable photopolymer material is DMP-128(R).

该屏幕22还可以包括一个透光的加强部件38，如丙烯酸材料，象聚甲基丙烯酸甲酯(PMMA)等等。也可以用聚碳酸酯材料。加强部件38是一个厚度在约2-4mm范围内的层状材料。屏幕22和加强部件是通过全息层26与加强部件38间的界面40彼此粘在一起的。可以采用粘合剂、辐射和/或热粘合技术。加强层的表面42还可以做下述一种或多种处理：着色，防眩光，涂覆涂层和涂覆防划伤涂层。The screen 22 may also include a light transmissive reinforcing member 38, such as an acrylic material, like polymethyl methacrylate (PMMA) or the like. Polycarbonate material can also be used. The reinforcement member 38 is a layered material having a thickness in the range of about 2-4 mm. The screen 22 and reinforcing member are bonded to each other by an interface 40 between the holographic layer 26 and the reinforcing member 38 . Adhesive, radiation and/or thermal bonding techniques may be employed. The surface 42 of the reinforcing layer may also be treated with one or more of the following: coloring, anti-glare, coating and anti-scratch coating.

屏幕的各个表面和/或其构造层，可以包含其它光学透镜或凸透镜阵列，以在不削弱三维全息投影屏幕较好的色偏性能的前提下控制投影屏幕除了色偏性能之外的其它性能特性方面，如已知用传统投影屏幕完成的。图4表示了第一个这样的改变，其中至少有两个全息元件被重叠或叠放。根据所示的实施例，在±40°视场范围内具有水平增益变化的第一全息元件，与在±20°视场范围内具有垂直增益变化的第二全息元件叠放在一起。图中的阴影指示出增益的变化，但是当没有光照时，实际的全息元件简单地表现为其表面范围内有散射。将水平和垂直增益变化全息元件重叠的效果基本等效于中心型全息元件；但是，亮度量值在水平方向和垂直方向将以不同的速率变化，这是因为水平扩展范围比垂直扩展范围大得多。Each surface of the screen and/or its structural layer may contain other optical lenses or convex lens arrays to control other performance characteristics of the projection screen except for the color shift performance without impairing the better color shift performance of the three-dimensional holographic projection screen aspect, as is known to be done with conventional projection screens. Figure 4 shows a first such variation in which at least two holographic elements are superimposed or stacked. According to the illustrated embodiment, a first holographic element having a horizontal gain variation over a field of view of ±40° is stacked with a second holographic element having a vertical gain variation over a field of view of ±20°. The shading in the figure indicates a change in gain, but when there is no illumination, the actual holographic element simply appears to have scattering across its surface. The effect of overlapping horizontal and vertical gain-varying holograms is essentially equivalent to that of a center-type hologram; however, the brightness magnitude will change at different rates in the horizontal and vertical directions because the horizontal expansion range is much larger than the vertical expansion range many.

图5是在±40°水平视角扩展范围内测得的屏幕中心点处作为白色峰值亮度百分比的屏幕亮度曲线图。图中的两条线分别表示仅仅采用水平变化全息元件时的亮度，和采用重叠的水平和垂直变化全息元件时的亮度。用重叠全息元件时的水平亮度变化基本相当于只有水平全息元件时的性能，或稍有改进。Fig. 5 is a graph of screen luminance as a percentage of white peak luminance at the center point of the screen measured within the extended range of ±40° horizontal viewing angle. The two lines in the figure represent the brightness when only horizontally varying holographic elements are used, and the brightness when overlapping horizontally and vertically varying holographic elements are used, respectively. The horizontal brightness variation with overlapping holographic elements is substantially equivalent to, or slightly improved upon, the performance of horizontal holographic elements alone.

在设计全息屏各种性能指标范围时，很难使屏幕同时达到所有所需的性能特性。叠放可使不同要求，如增益的水平变化和垂直变化得到分别对待，对其要求可能不同，如由于屏幕的比例不同(如宽度值比高度值更大)，或需要在一个轴上偏离轴而在另一个轴上保持对中等等。该方案不局限于两个叠放在一起的具有线性和其它增益变化的全息元件，也可以应用于附加叠放的全息元件，以控制屏幕透过光的色差和其它方面，或叠放具有更好边缘亮度和色偏等性能的元件。When designing the range of various performance indicators of a holographic screen, it is difficult to make the screen achieve all the required performance characteristics at the same time. Stacking allows different requirements, such as horizontal and vertical changes in gain to be treated separately, for which requirements may be different, e.g. due to different proportions of the screen (e.g. width values are larger than height values), or need to be off-axis on one axis And stay centered on the other axis and so on. The scheme is not limited to two stacked holographic elements with linear and other gain changes, but can also be applied to additionally stacked holographic elements to control the color difference and other aspects of the light transmitted through the screen, or stacked with more A component with good edge brightness and color cast.

图6表示了一种变化，其中中心型全息元件26(即具有水平和垂直增益变化)上叠置有直线型菲涅尔透镜29和31，以产生水平和垂直准直的效果。由于直线型菲涅尔透镜可以比圆形菲涅尔透镜更廉价地压轧或辊压出来，所以本实施例在成本意义上是可取的。圆形菲涅尔透镜占传统屏幕成本的60％。直线型菲涅尔透镜的成本大约是圆形菲涅尔透镜的25％。所以，可以节约30％的成本(即：(25％+25％)×60％＝30％)。对于如上述所讨论的水平和旋转的全息元件而言，如果需要，直线型菲涅尔透镜可以在水平和/或垂直视角范围内变化，以便改变焦距长度而与垂直和水平的跨度无关。两个叠置的直线型菲涅尔可以按照任意次序放置在全息元件后面。Figure 6 shows a variation in which a central holographic element 26 (ie with horizontal and vertical gain variation) is superimposed with linear Fresnel lenses 29 and 31 to create a horizontal and vertical collimation effect. This embodiment is desirable in a cost sense since a linear Fresnel lens can be rolled or rolled out more cheaply than a circular Fresnel lens. Circular Fresnel lenses account for 60% of the cost of traditional screens. Linear Fresnel lenses cost approximately 25% of circular Fresnel lenses. Therefore, 30% cost can be saved (ie: (25%+25%)×60%=30%). For horizontal and rotational holographic elements as discussed above, the linear Fresnel lens can be varied, if desired, over the horizontal and/or vertical viewing angles to vary the focal length regardless of the vertical and horizontal span. Two stacked linear Fresnels can be placed behind the holographic element in any order.

Claims

1. back side image projection screen comprises:

First linear Fresnel lens comprises first side on plane and has second side of first lenslet; With

Second linear Fresnel lens, comprise first side on plane and have second side of second lenslet, described first linear Fresnel lens is adjacent to the described second linear Fresnel lens setting, thereby makes described first lenslet and described second lenslet be provided with orthogonally basically.

2. the back side image projection screen of claim 1, wherein first side on the plane of first linear Fresnel lens is adjacent to the second side setting of second linear Fresnel lens.

3. the back side image projection screen of claim 1, wherein first side on the plane of first linear Fresnel lens is attached to first side on the plane of second linear Fresnel lens.

4. the back side image projection screen of claim 3, wherein first linear Fresnel lens and second linear Fresnel lens stack together to form single plate.

5. the back side image projection screen of claim 1 wherein forms first linear Fresnel lens and second linear Fresnel lens by extruding.

6. the back side image projection screen of claim 1, wherein first and second linear Fresnel lens comprise that a plurality of lenslet plates that adhere to are to form serialgram.

7. the back side image projection screen of claim 6 wherein adheres to the lenslet plate on every side at the horizontal axis of first linear Fresnel lens and the vertical axis of second linear Fresnel lens.

8. the back side image projection screen of claim 7 wherein adheres to the lenslet plate, and the lenslet of winning is extended towards horizontal axis, and second lenslet extends towards vertical axis.

9. back projection system comprises:

Image display is used for optical imagery is throwed towards the back side image projection screen; With

The back side image projection screen that comprises first linear Fresnel lens and second linear Fresnel lens, wherein first linear Fresnel lens comprises first side on plane and has second side of first lenslet, second linear Fresnel lens comprises first side on plane and has second side of second lenslet, described first linear Fresnel lens is adjacent to the described second linear Fresnel lens setting, thereby makes described first lenslet and described second lenslet be provided with orthogonally basically.

10. the back projection system of claim 9, wherein first side on the plane of first linear Fresnel lens is adjacent to the second side setting of second linear Fresnel lens.

11. the back projection system of claim 9, wherein first side on the plane of first linear Fresnel lens is attached to first side on the plane of second linear Fresnel lens.

12. the back projection system of claim 11, wherein first linear Fresnel lens and second linear Fresnel lens stack together to form single plate.

13. the back projection system of claim 9 wherein forms first linear Fresnel lens and second linear Fresnel lens by extruding.

14. the back projection system of claim 9, wherein first and second linear Fresnel lens comprise that a plurality of lenslet plates that adhere to are to form serialgram.

15. the back projection system of claim 14 wherein adheres to the lenslet plate on every side at the horizontal axis of first linear Fresnel lens and the vertical axis of second linear Fresnel lens.

16. the back projection system of claim 15 wherein adheres to the lenslet plate, and the lenslet of winning is extended towards horizontal axis, second lenslet extends towards vertical axis.

17. the back projection system of claim 9, wherein image display is the array of horizontally disposed cathode ray tube.