BACKGROUND OF THE INVENTION The invention relates to an apparatus as recited in the preamble of Claim 1. JP Kokai 6-237429 discloses a screen organization for allowing to display 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.

SUMMARY TO THE INVENTION In consequence, amongst other things, it is an object of the invention to assign resizing facilities to a projection screen device as recited, for being able to form images in distinctly different sizes, while keeping the physical screen dimensions in size with the actual image.

Now therefore, according to one of its aspects the invention is characterized according to the characterizing part of Claim 1. 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 as recited in Claim 2. 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'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. Further advantageous aspects of the invention are recited in dependent Claims.

BRIEF DESCRIPTION OF THE DRAWING These and further aspects and advantages of the invention will be discussed more in detail hereinafter with reference to the disclosure of preferred embodiments, and in particular with reference to the appended Figures that show: Figures lA-lC, user appearance of an inventive apparatus; Figures 2A-2C, screen arrangements of such apparatus; Figure 3, control mechanics of such apparatus; Figures 4A-4C, shape fixating elements of the apparatus; Figure 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'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, Figures 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 Figure 1A, the screen is fully hidden behind the outer appearance. In Figure 1B, a relatively small screen such as 45X60 centimetres is used in situations where a living-room size is preferred. The rest of

the screen structure remains hidden. In Figure 1C, a relatively large screen such as 90X120 centimetres, serves for situations such as lecturing or a group amusement situation.

Figures 2A-2C show screen arrangements of the apparatus, in respective correspondence with Figures lA-l C. In Figure 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 Figure 2B, the screen is hidden only halfway and halfway unrolled. In Figure 2C, screen is fully exposed and also, fully unrolled.

Figure 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, one 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.

Figures 4A-4C show shape fixating elements of the apparatus. In Figure 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 Figure 4B, central vertical bar 46 will diminish screen camber by effectively halving screen width. In Figure 4C, bar 48 is shown raised together with the screen.

Figure 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.