Abstract:
A variable size projection screen apparatus inputs an image and generates a beam to project the image on a screen. A sizing facility can resize the image on the screen in at least two different sizes. A motor arrangement can physically resize the screen in a lateral direction to at least two distinct widths.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     Kokai (JP 6-237429) discloses a screen organization for allowing display of TV images both at a classic aspect ratio of 3:4 and also at a wider aspect ratio of 9:16, by shuttering lateral strips of the screen so that the narrower screen will be filled completely by the 3:4 image. This procedure will keep the image height, as well as the overall size of the screen arrangement, constant. 
     The inventor has recognized a need to allow using a single projection screen arrangement for generating images at different sizes, and to assign resizing facilities to a projection screen device to form images in distinctly different sizes, while resizing the physical screen dimensions in accordance with the actual image. 
     According to the invention, the screen proper is physically resizable in a lateral direction on at least two distinct levels. It has been found that such physical resizing is more flexible and less distracting, and more pleasing to a viewer than the prior art arrangement. 
     Advantageously, the apparatus is arranged for physically resizing the screen in two directions to images that have substantially uniform height-to-width ratios and substantial differences among corresponding dimensions. Now, prior art exclusively has diminished the effective screen width by only −25% with respect to the wider image. The present invention allows a much wider variation in physical screen size, that may depend on such circumstances as the size of the audience, the nature of an actual program, and the viewer&#39;s seating distance from the screen and/or other viewer activities. The invention may then use various different combinations, such as the standard aspect ratio at a smaller size, while allowing Wide Screen TV aspect ratio at a larger size. In this way, the invention allows screen area variations by factors such as 2, 4, or even more. The invention is by and large much more flexible than the prior art. On the other hand, especially for use with present-day high quality image rendering, using such quasi-screen matter as a white wall, a reversed picture or the like as a basis for projection on such wall has proved to be insufficient. 
     The invention also relates to screen device for use with such apparatus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIGS. 1A-1C, user appearance of an inventive apparatus; 
     FIGS. 2A-2C, screen arrangements of such apparatus; 
     FIG. 3, control mechanics of such apparatus; 
     FIGS. 4A-4C, shape fixating elements of the apparatus; 
     FIG. 5, an exemplary mechanical setup of the apparatus. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The embodiments infra will be detailed for front projection, but rear projection or even the use of both in a single hardware arrangement may in principle benefit from similar advantages, depending on the providing of a suitable screen material for implementing the physical size variations disclosed hereinafter. The selecting of appropriate screen materials would be clear to a person skilled in the art. As regarding the occasions for use, audience size may vary from a single person viewing a news program to a kindergarten party looking at a show like The Muppets. The nature of the program may range from the rendering of Teletext and similar images, to a wide-screen Discovery film, or even the generating of a decorating (still) image. Also, the viewer&#39;s seating distance may vary from a stationary writing-desk setting to a situation where the viewer is distant and moving around like during ironing or vacuum cleaning. 
     Now, FIGS. 1A-1C show various user appearances of the inventive apparatus. As shown, a cabinet or other shape may be used to substantially fully hide the screen when not in use. Here, the height of the cabinet is equal to the maximum height of the screen, and similarly for the width of the cabinet. The depth of the cabinet need not be larger than necessary for hiding the screen mechanism, if such is wished at all. Generally, a few centimetres will suffice but the cabinet may serve further useful purposes. In FIG. 1A, the screen is fully hidden behind the outer appearance. In FIG. 1B, a relatively small screen such as 45×60 centimetres is used in situations where a living-room size is preferred. The rest of the screen structure remains hidden. In FIG. 1C, a relatively large screen such as 90×120 centimetres, serves for situations such as lecturing or a group amusement situation. 
     FIGS. 2A-2C show screen arrangements of the apparatus, in respective correspondence with FIGS. 1A-1C. In FIG. 2A, the screen is fully hidden and substantially completely scrolled-in by sideway scrolls  40 ,  42 , so that only the vertical size corresponds to that of the maximum screen. Without restriction, the diameters of the scrolls may be as little as five centimetres. In FIG. 2B, the screen is hidden only halfway and halfway unrolled. In FIG. 2C, screen is fully exposed and also, fully unrolled. 
     FIG. 3 shows exemplary control mechanics of the apparatus. Rectangle CDFE is the hiding shape. Rectangle ABCD is the full-size screen, at High Definition TV aspect ratio. Rectangle GHIJ is the screen when halfway unrolled at the same aspect ratio. The widths of the scrolls proper have been ignored. The line KL is the central axis of the screen when rolled in. Hatched lines KGA, KHB, LJD, and LIC indicate the apparent paths of the screen structure corners during roll-out. Dotted lines indicate screen narrowing to classical TV aspect ratio of 3:4. The screen sizes may be limited to the three cases as shown, but it may be feasible to use various intermediate values as well. If only two formats are used, the hiding structure may be narrowed to correspond to that of rectangle GHIJ. Further scrolling-in may then be foregone. Screen mechanics may be more or less continuous through two motor arrangements, cone for vertical and one for unscrolling. Alternatively, screen corners may be moved by parallelogram structures if only a few positions need be realized. Combinations of these features may be feasible as well. 
     FIGS. 4A-4C show shape fixating elements of the apparatus. In FIG. 4A, a top bar will keep the upper edge of the screen straight; various mechanisms may be used to let the scrolling avoid problems due to the lack of flexibility in the bar. In FIG. 4B, central vertical bar  46  will diminish screen camber by effectively halving screen width. In FIG. 4C, bar  48  is shown raised together with the screen. 
     FIG. 5 shows an exemplary mechanical setup of the apparatus for use with projection television. The image signal is fed on antenna  20 . Block  22  symbolizes all image processing and control functionality, inclusive of size control. As shown, image angle  30  is fixed. Often, lower beam edge will be horizontal. For ceiling mount, upper beam edge will be horizontal. The setup necessitates the moving of processing block  22  along floor  24 . The moving will then immediately determine effective image size. Alternatively, zooming across different angle values with corresponding resizing of the image is feasible. Once the necessary screen size is known, through taking into account the image distance and angle, the size of screen  34  must be controlled in line with the foregoing. This is mechanically and automatically effected by mechanism  32 , that may get necessary control signals from central control  22 , such as by wireless transmitter  26  along link  28 . In addition to the above, image angle may need additional vertical variation to cope with the apparent vertical screen position when amending the screen size. 
     A different automatism can operate through an in-screen sensor that picks up a predetermined projected image. For operation, the screen arrangement sends a control signal that will drive the projector into “determine screen size mode”. Next, a sensor on the active screen will on the basis of appropriate details of the image such as content, check whether the screen has indeed the correct size. Such content may be a special marker that is projected at a corner of the image on a dedicated sensor. Alternative manners for wireless transmission of control signals are widely known in the field of consumer audio/video.