WO2007081220A1

WO2007081220A1 - Dynamic pixel structure

Info

Publication number: WO2007081220A1
Application number: PCT/NO2007/000013
Authority: WO
Inventors: Benny Svardal; Richard Berglind; Gunnar Hedin
Original assignee: Ignis Display As
Priority date: 2006-01-13
Filing date: 2007-01-12
Publication date: 2007-07-19

Abstract

The present invention provides a system and Tunable Diffraction Grating with dynamic pixel structure in a line scanning projection display system. By setting an arrangement of distribution in the system, pixel information related to image lines to be displayed are conveyed to grating settings of the modulator according to a pixel format of the image line to be displayed. The formation of gratings can be achieved on an individual basis for each pixel, and each grating can be individually adjusted in length to, for example compensates aberration errors.

Description

Dynamic Pixel Structure

The present invention is related to scanning line color display systems, and particularly to a system and device for dynamic adaptation of different pixel formats, pixel structures, image corrections etc. related to display system requirements, according to the independent claims 1 and 22.

Usually, all signal sources to be used in a modern display system are digitally generated, or an analogue signal source is converted in an analogue to digital converter before being displayed in the display system. The main characteristics of such signals are an underlying pixel format and resolution. The format is expressed in the form of number of horizontal pixels by number of vertical pixels (H x V). Today, there are three common industry formats, the DVD format (720 x 480), and the two HDTV formats of (1280 x 720) & (1080 x 1920), respectively.

Current display types aimed for the high-definition market have a fixed digital pixel format. This is the standard both for flat panel displays, e.g., PDP, as well as for projection type display systems based on DMD, LCOS, or LCD technology. The new, recently proposed technologies for projection display systems based on one-dimensional light modulator arrays for line scanning projection using laser illumination, e.g., GLV and GEMS comprise a fixed digital pixel format in one direction of the image.

EP 1612596 Al disclose how to manufacture and produce adjustable optical elements based on polymer and liquid crystal composites.

The article "Elastomer-Based Diffractive Optical Modulator", by Srinivasan Uma et al, IEEE Journal of Selected Topics in Quantum Electronics, vol. 10, No. 3. May/June 2004 disclose a device structure for providing a diffractive optical modulator fabricated using a elastomer layer.

JP 63232241 disclose a methode for manufacturering huge plasma displays by using grouping of electrodes.

WO 2004/023197 Al disclose a variable optical modulator for optical communication using an adjustable dynamic grid. When the pixel format of a signal or image does not match the original pixel format of a display system, the image needs to be rescaled, up or down, to match the display system's format. Failing to do so causes the image to overfill or underfill the screen. In prior art, rescaling is done by digitally interpolating the image pixels and then resampling them to the display system's original pixel format, for example in a digital video processor as known to a person skilled in the art.

For example, consider rescaling a 720 x 480 DVD image into 1280 x 720 resolution image, one line at a time, which is the simplest case. No matter how it is done, periodic irregularities (which are displayed as visual artifacts) arise when mapping 720 pixels into 1280 pixels, and these artifacts will be quite noticeable whenever there are fine image details. There is always a loss of sharpness in images when rescaling since image pixels are combined by varying amounts of pixels. In addition, rescaling produces increased pixilation artifacts.

Therefore there is a need for a display system capable of displaying images of different pixel format and resolution than the display system originally provides without loss of image quality.

According to an aspect of the present invention, rescaling can be avoided by providing access to parts of individual pixels. According to an example of embodiment of the present invention, this objective may be achieved with a Tunable Diffraction Grating (TDG) modulator comprising a dynamically selectable grouping of electrodes providing surface modulations of a gel or membrane in the TDG modulator constituting pixels in the modulator. A TDG modulator used in a line scanning projection display system comprise typically a fixed length pixel array constituted by electrodes supported on a substrate adjacent to a gel or membrane in the TDG providing grating patterns on a surface when signals are applied on the electrodes, as known to a person skilled in the art. Typically, four electrodes are used to form a pixel. According to this aspect of the present invention, each electrode may be dynamically assigned to different pixels. For example, four electrodes of a pixel may be assigned to two new pixels comprising two electrodes each, respectively, etc. Three electrodes may be grouped into pixels, and so on. According to yet another aspect of the present invention, pixel grouping may be done with varying number of electrodes in each pixel grouping. Therefore, just by providing access to individual electrodes, any fixed length pixel array of a TDG modulator may be adjusted to another pixel format with the same fixed total array length, and also be adjusted to another intended pixel structure, or be arranged into a special pixel structure, for example to compensate for different optical errors or for performing corrections which may be necessary in a display system.

According to an aspect of the present invention, a distributor and/or distribution function and/or distribution structure incorporated into the display system may provide grouping of electrodes constituting the pixels in the TDG modulator. The actual grouping of the electrodes may be done by this arrangement of distribution on basis of user interaction, user specification, or as a result of findings from an analysis program doing an analysis of images to be displayed. Such analysis may be executed to be able to find pixel structure formations that compensate for different optical deficiencies in the system, for example.

The arrangement of distribution comprising a distributor and/or distribution function and/or distribution structure may be located between sources of pixel information related to image lines to be displayed, for example an image memory, and driving electronics providing voltage settings of connected electrodes according to the present pixel information. The actual conversions from binary pixel information to voltage are known by a person skilled in the art. According to examples of embodiments of the present invention, any combination of structural distribution (for example signal busses), distributor (video switch, cross bar switch etc.) and distribution function (for example program executed in an attached computer or processor) is to be viewed as being inside the scope of the present invention. The actual arrangement of distribution may also have all or some structural features of the arrangement implemented between the driving electronics and the connected electrodes, not only between the pixel information source and the driving electronics. In the following description, some examples of embodiments illustrating some examples of distribution according to the present invention are outlined. Any other combination of structural and functional structures that provides the distribution as teached in the present invention is regarded as being inside the scope of the invention.

According to an aspect of the present invention, access to each individual electrode may be achieved by providing a memory structure for storing pixels, wherein the output of the pixel memory structure is in communication with driving electronics of each electrode, as known to a person skilled in the art. According to an example of embodiment, each pixel memory structure receives pixel information from an image memory, and whenever a grouping of electrodes is to be constituted, member electrodes of each grouping receives the same pixel information in each respective pixel memory structure from the image memory, thereby constituting a dynamic pixel structure in the modulator.

According to yet another example of embodiment of the present invention, the modulator comprise a limited number of pixel configurations, wherein the grouping of electrodes corresponding to each limited number of pixel configurations is selected by addressing analogue multiplexers/demultiplexers, or a video switch, arranged between the plurality of pixel memory structures and the electrodes.

According to another example of embodiment of the present invention, the dynamic grouping of electrodes constituting pixels may be utilized to provide a significant increase in image resolution by providing ¹A pixel shifts between lines from subsequent images that are displayed in the system.

According to yet another example of embodiment of the present invention, the dynamic pixel structure is utilized to compensate aberration errors.

According to yet another example of embodiment, aberration compensation is achieved automatically by feedback from a camera viewing the displayed image thereby providing an automatic alignment of images displayed on a screen.

According to yet another example of embodiment of the present invention, the dynamic pixel structure is utilized to relate pixel size to projected positions of pixels onto a cylindrical 180° screen.

According to yet another example of embodiment of the present invention, the dynamic pixel structure is utilized to provide sub pixel modulation, for example, to enhance grey scale resolution in pixels. According to an aspect of the present invention, such sub pixel modulation may be achieved by a program running in an image processor in communication with an image memory and the modulator providing intended modulation via control of the corresponding electrodes in the modulator.

According to yet another aspect of the present invention, the dynamic pixel structure is utilized to adapt projected images to human perceptive behavior, for example to enhance human interpretation ability of MRI or mammography pictures. For example, the human eye has a much better vernier resolution than point resolution. This may be utilized, according to the present invention, by increasing dynamically and locally the pixel resolution around edges providing smooth well defined borders in stead of "jagged" lines typical for pixel structures. Contrast differences in images are perceived much better by humans when there are smooth surfaces in stead of artifacts caused by the digitalization with a fixed resolution. According to yet another aspect of the present invention, such enhancements may be achieved by increasing or reducing the number of pixels related to local parts of in an image.

Figure 1 illustrates an example of a Tunable Diffraction Grating (TDG) component according to prior art.

Figure 2 illustrates a typical electrode pattern in prior art.

Figure 3 illustrates an electrode pattern according to the present invention.

Figure 4 illustrates a segment comprising 4 electrodes per pixel according to an example of embodiment of the present invention.

Figure 5 illustrates a segment comprising 6 electrodes per pixel according to an example of embodiment of the present invention.

Figure 6 illustrates another example of embodiment according to the present invention.

Figure 7 illustrates an example of image generation according to an example of embodiment to the present invention.

Figure 8 illustrates an example of image generation according to an example of embodiment to the present invention.

Figure 9 illustrates another example of embodiment of the present invention.

Figure 10 illustrates an example of a display system according to the present invention.

Figure 11 illustrates an example of embodiment of the present invention providing aberration compensation.

Figure 12 illustrates an example of a display system according to the present invention used for an 180° cylindrical screen. The present invention is preferably based on tunable diffraction gratings. Such gratings have been disclosed in the literature, see for instance articles and books published by Guscho in Russia (e.g., Guscho: Physics of reliefography, 1992 Nauka Moscow). The basic principles of these modulators are well known by a person skilled in the art, and have been used for projection applications since the introduction of the Eidophor project over 60 years ago.

The working principle of the tunable diffraction grating is based on light diffraction due to surface modulation in a thin gel layer or a membrane (elastomer, polymer) with equal optical and functional characteristics. An example of embodiment of such a modulator is illustrated in figure 1. The modulator comprise a thin layer of gel (or membrane, elastomer etc.) 1, adjacent to a transparent modulator prism 2. The gel membrane is index matched to the prism glass, and the gel has low light absorption (less than 2 % in a typical system). Typically, the gel layer is 15-30 μm thick. Electrodes, 3, are processed on a flat substrate layer separated from the gel surface by a thin air gap (5-10 μm thick). The spacing can be arranged differently as known to a person skilled in the art. An ITO (indium tin oxide) layer, 4, may optionally be used to apply a bias voltage across the gel and the air gap. As a result, a net force acts on the gel surface due to the electric field. By applying local signal voltages on the electrodes, forces are applied on the gel surface, resulting in a surface modulation.

To achieve good contrast display modulators based on diffractive grating technology, the modulator needs to provide several grating periods (at least two) within each pixel. For an elastomer (gel) based modulator this is achieved if several electrodes are grouped together such that the applied signal voltage on those electrodes result in a local surface modulation of the gel, thus enabling the control of individual modulator pixels. An example of this arrangement is illustrated in figure 2. In this example, a pixel is defined by grouping four signal electrodes together. To generate an image, each group of electrodes receives an individual image signal 5a, 5b, and 5c. A grounded electrode grid, 6, is intertwined with the signal electrodes providing a ground electrode present between two adjacent signal electrodes. Incoming light from a light source (in a co lour display system, the light source may be one of red, green or blue laser light) is diffracted by the pattern generated on the surface of the gel, wherein the diffraction setting of an individual pixel represent a gray scale or co lour scale for that particular pixel for a particular point of a line in the image that currently is displayed in the system. Display optics projects the modulated light onto a screen for example, as known to a person skilled in the art. In a co lour display system, three TDG modulators may be used, one for each of the colors RAG and. The projection optics will combine all three pixels into one pixel point of the line on the projection screen.

In a prior art, display systems of this kind, a display memory usually comprise the image information as pixel information for R₅G an B pixels comprising an 8 bit, 16 bit or even 24 bit gray scale or color code for each pixel.

Pixel information related to an image line to be displayed is then outputted from the image memory to electronics providing correct driving voltages of the electrodes 3, as depicted in figure 1, and as known to a person skilled in the art.

According to an aspect of the present invention, a fixed predefined pixel structure in the display system may be removed by individually operating each single electrode or a subgroup of electrodes.

The arrangement of distribution comprising a distributor and/or distribution function and/or distribution structure may be located between sources of pixel information related to image lines to be displayed, for example an image memory, and driving electronics providing voltage settings of connected electrodes according to the present pixel information. The actual conversions from binary pixel information to voltage are known by a person skilled in the art. According to examples of embodiments of the present invention, any combination of structural distribution (for example signal busses), distributor (video switch, cross bar switch etc.) and distribution function (for example program executed in an attached computer or processor) is to be viewed as being inside the scope of the present invention. The actual arrangement of distribution may also have all or some structural features of the arrangement implemented between the driving electronics and the connected electrodes, not only between the pixel information source and the driving electronics.

The pixel array of the modulator is fixed in length on the supporting substrate of the electrodes, but according to an aspect of the present invention, a pixel is no longer defined by its electrode geometry by itself. Applying the same signal voltage corresponding to a pixel on a number of signal electrodes provides an example of pixel grouping according to the present invention. As easily understood by a person skilled in the art, rearranging this application of voltages provides a new pixel grouping, and hence the modulator may be adapted to different pixel formats, pixel structures etc. In an example of embodiment of the present invention, the size of a pixel as defined by the number of electrodes depends on the image pixel format of the image source signal, wherein the pixel format defines the grouping of the electrodes. The only requirement for the grouping is that a sufficient number (at least two) of grating periods are included in each pixel (at least two electrodes per pixel).

In the following, examples of arrangement of distributions are described. The primary task of the arrangement of distribution is to provide a communication path between pixel information related to pixels of an image line to be displayed and corresponding driving electronics converting pixel information into correct voltage levels on the member electrodes of each pixel. By letting the arrangement of distribution establish connections between pixel information and driving voltage electronics, and provide setting of the voltage onto the correct number and positions of electrodes, the purpose of the present invention is achieved.

According to an example of embodiment of the present invention, each individual electrode is connected to separate respective driving electronics, where all electrodes have a separate memory block providing storage of a pixel structure including gray scale or color parameters related to downloaded images. The downloading may be line by line (either vertical or horizontal lines of the image) or a complete image, in which case read out electronics will provide the driving electronics and the modulator with successive appropriate image line content. According to the content present at the output of the memory block, the present voltage level on the connected electrode of that memory block will be defined, as known to a person skilled in the art. Whenever a number of electrodes are defining a pixel, the same content is stored in the corresponding memory blocks. According to an example of embodiment of the present invention, each of the corresponding memory blocks is in communication with an image memory. The image memory may be part of the display system itself, or is part of a separate computer system, or the image memory may even be a DVD disc, or even a network connection to a remote server computer. The only requirement according to this example of embodiment of the present invention, is that a control system, for example software running in a local processor in the display system, can read out pixels from the image memory, and that memory blocks store the same pixel information according to the pixel format related to the member electrodes of each pixel. The number of memory blocks forming a pixel is defined by the pixel format of the source signal and the number of electrodes present in the modulator in the display system.

According to an example of embodiment of the present invention, a common data buss interconnects the memory blocks with the image memory. Each pixel from the image memory is communicated serially over the common data buss. Control signals clocks the content present on the data buss into the corresponding memory blocks constituting a pixel. For example, pixel X is defined by electrodes a, b, c and d according to the pixel format of the source signal and the number of electrodes in the modulator. Therefore, whenever pixel X is present on the data bus, control signals corresponding to the memory blocks related to the electrodes a, b, c and d are activated, thereby transferring the content on the data buss into the activated memory blocks constituting the pixel X. The generation of control signals may be under supervision of a processor running in the display system as known to a person skilled in the art. According to the pixel format in the source signal, which is identifiable as known to a person skilled in the art, the electrodes are grouped. The chosen grouping then defines the activation of the corresponding control signals for each memory block. As can be understood by a person skilled in the art, this scheme enables dynamic allocation of electrodes to pixels. According to another example of embodiment of the present invention, a pixel maybe defined by electrode a,b and d (omitting electrode c of a particular reason), then the memory blocks in communication with electrodes a,b and d are activated.

According to an example of embodiment of the present invention, the activation of the control signals is achieved by a two level addressing scheme. The activation signal of a particular memory block comprises the following logical equation:

(Group _adress_selected) AND (Group _adr ess _bif) AND (Clock_signal) Group jadress _s elected is a decoded signal of a binary address Group _adress that divides the number of memory blocks into groups. For example, if the modulator comprise 1024 electrodes, and it is practical to divide or group the memory blocks into groups comprising eight memory blocks each, Group_adress must be a number between 0 and 127 to be able to be used in a decoder providing the correct Group _adress_selected signal, as known to a person skilled in the art. Group _adr ess _bit is for example an 8 bit long unary address string (0 to 7) pointing at individual memory blocks inside each grouping of memory blocks. For example, to address block number 5 in group 9 would be possible with an address {Group _adress=9, Group _adress_bit=00000100). As can be understood by a person skilled in the art, it is then possible to address the 8 memory blocks in each memory block group in parallel. Therefore, if a pixel Y should be stored in memory block 0,1,2 and 3 in group 9, for example, a Group _adr ess _bit=l 1110000 would provide parallel loading of the content on a common data buss connected to the memory blocks. As can be understood, if a processor running in the display system can utilize 16 bits word, a Group jxdressjbit size of 16 would be preferable, if the word size is 32, this would be even more beneficial for an embodiment of this address scheme.

An aspect of this example of embodiment of the present invention is that any combination of pixel structures is definable. Whenever the system is used to display a standard pixel format, the corresponding grouping of electrodes is used as described above. However, the total freedom in defining a pixel structure in a TDG based modulator according to the present invention makes it also possible to accommodate strange pixel definitions which may be used to display artistic images in the display system, for example. Therefore it is inside the scope of the present invention to support any combination of grouping of electrodes. If there are n electrodes in the modulator, there will be n! combinations of possible electrode combinations that are inside the scope of the present invention.

Other examples of use of strange pixel structures comprise human interpretation of images. For example, the human vision has much better vernier resolution than point resolution. Smooth lines in stead of "jagged" lines maybe achieved according to the present invention by providing a higher pixel resolution locally in subparts of an image. Contrast differences are much better perceived by humans if artifacts due to digitalization are not dominant in the image. According to an example of embodiment of the present invention, a user may alter the pixel resolution in subparts of an image by using a cursor to select these parts. These selections are communicated to for example a display processor in the system providing a reformatting of the lines to be displayed related to these selections. These features of the present invention may for example be used when studying MRI and mammography images. According to yet another example of embodiment of the present invention, an analysis program may identify for example such "jagged" lines, and by providing a partitioning of image lines comprising "jagged" sections, and increasing the resolution in such partitioning comprising unwanted image details, the image will be displayed in a system according to the present invention with enhanced interpretability by humans.

According to yet another example of embodiment of the present invention, any combination of electrodes constituting a pixel may also be regarded as comprising sub pixels defined by subsets of electrodes constituting the pixel. In this manner, an additional modulation may be achieved inside a pixel definition. According to an example of embodiment of the present invention, the sub pixel ability may be utilized to increase the grey scale resolution of the pixel, as can be understood by a person skilled in the art. For example, a pixel constituted by electrodes a,b, c and d may have improved grey scale resolution by additional modulation of electrodes b and c.

Whenever a display system comprising an embodiment of the present invention supports only a choice of pixel formats as provided by source signals, the embodiment of the system may be stricter in its structure. For example, if the example of embodiment is restricted to only support the industry DVD pixel format, and the two HDTV formats, the system may be tailored to only support these three formats. Accordingly, if there are 4096 electrodes in the modulator, the grouping of pixels for DVD formats would comprise at least 5 electrode for each pixel, and 3 respective 2 electrodes for the two HDTV formats. Accordingly, the memory block structure described above may be substituted with an analog multiplexer/demultiplexer structure inserted between driving electronics and electrodes, as known to a person skilled in the art. The multiplexer/demultiplexer structure would then receive activation signals from for example a processor enabling the correct voltage level on each connected electrode. The same functionality as provided by the multiplexer/demultiplexer structure as described above may also be achieved by employing an addressable video switch structure as known to a person skilled in the art.

Figure 3 illustrates an example of embodiment of the present invention. Each signal electrode is individually operable with different image signals, 5a-l. A pixel is generated by applying the same image signal to a number (at least two) of adjacent signal electrodes.

Figure 4 is another example of embodiment of the present invention, wherein each pixel is generated by four electrode line pairs.

Figure 5 is yet another example of embodiment of the present invention, wherein each pixel is generated by six electrode line pairs.

It should be noted that when a voltage signal is applied to a group of adjacent signal electrodes, a sinusoidal grating structure is generated in the elastomer or gel surface. The surface structure is continuous across the pixel area resulting in a 100 % fill factor regardless the size of the pixel.

Figure 6 illustrates an example of embodiment of the present invention where the dynamic pixel structure is used to increase the image resolution. In this example, four electrode line pairs are used to generate a pixel, 7a, 7b, 7c... with sufficient contrast. By regrouping the electrodes to constitute a pixel by line 8a, 8b... it is obvious that the line image modulated by this line is shifted ¹A pixels in the line direction. According to an aspect of the present invention, the image resolution is then increased by this shifting of the current pixel line pairs by two (corresponding to ¹A pixel) line pairs between subsequent image frames. The following image frame is thus generated using pixels 8a, 8b... which in turn is followed by an image frame using pixels 7a-c and so on.

Figure 7 illustrates an example of this effect according to the present invention. Figure 7a illustrates an image generated line by line with pixels 7a, 7b, 7c....7j, where j is the number of pixels in the line. 7b illustrates the next frame constituting pixels from electrodes 8 a, 8b....8k, wherein k is the number of pixels of an image line that is possible when the line is shifted ¹A pixels in the direction of the line. When these two images are superimposed on each other by projection optics in the system, the image illustrated in figure 7c provides an image with significant increased resolution compared to the original image without increasing the physical dimension of the modulator design.

Figure 7 illustrates an example of image generation using a display modulator as depicted in figure 6. Odd frames, a, are displaced by ¹A pixel in vertical and horizontal directions compared to the even frames, b. When superimposed the frames generate a high resolution image, c.

Figure 8 is an illustration of an example of image generation using a display modulator as depicted in figure 6 when the native resolution is greater in the scanning (horizontal in this figure) direction. Odd frames, a, are displaced by ¹A pixel in the vertical compared to the even frames, b. When superimposed the frames generate a high resolution image, c.

Figure 9 is an illustration of a modulator with the grating direction perpendicular to the pixel pitch as opposed to modulators depicted in figure 1 through figure 6. figure 9a shows a top view of the pixel electrodes, 5, and ground electrodes, 6. Figure 9b shows a side view illustrating one pixel grating. A modulator as the one depicted in figure 9 diffracts light in a direction perpendicular to the pixel direction, which makes the pixel size independent of the grating period. This configuration makes it easier to create small pixels and thus high resolution displays. However, there is a gap between the pixels which may lead to less than 100 % fill factor. If this gap is made small enough, the fill factor of the pixels at the gel surface will approach 100 % as the high spatial frequencies is suppressed by the physical properties of the elastomer. The suppression of the high spatial frequencies in the elastomer surface limits the size of individual pixels rendering a minimal pixel size. The procedure to increase resolution in the image depicted in figure 6 can be used in this configuration as well. Instead of having a modulator where each pixel is of the minimum size allowed by the elastomer, each pixel is half that size. For each image frame an image pixel is generated by using two adjacent image pixels and a shift of one modulator pixel (¹A image pixel) between subsequent frames.

Figure 10 depicts a block diagram illustrating an example of an embodiment of an image display system generating an image as depicted in figure 7 or figure 8. A light source, 11, directs light through a system of source optics, 12 onto a light modulator, 13. The modulation is achieved via an image signal, 5, fed through an image processing unit, 9, which processes the image and directs control signals through a synchronization unit, 10, which controls any time delay present in the scan direction between subsequent frames. Projection optics, 14, images the modulator row onto a single line on the screen and a scanning device, 15, scans the line across the screen creating a 2D image, 16.

Figure 11 illustrates how an example of embodiment of the present invention may compensate for aberration errors in a display system. A distortion as depicted in figure 11a typically arise when a display apparatus is not properly aligned relative to a screen used for displaying the images. The illustration in figure 1 Ib depicts how the image should appear on the screen. The vertical lines in the illustration representing the image corresponds to a current image line that at present is being modulated in the pixel array of the modulator. The intersections between the dotted horizontal lines and the vertical lines in figure 11a illustrate the portions of each vertical line that is used for image formation.

To be able to identify the intersections described above, a camera may be used. If the image frame of the camera is properly aligned horizontally and vertically, an image of the displayed image on the screen would reveal the intersections necessary to calculate how the different image lines should be reformatted to be able to accommodate a properly aligned vertical and horizontal image, just by following the directions provided by the aligned camera.

However, a camera is not always properly aligned. For example, the camera may be an integral part of a projector, and whenever the projector is out of alignment, so will the camera be. In such cases, a laser pointer may be used to identify three points on the screen that will define the correct aligned contour of the screen. When pointing, a user may take a picture, and by combining three successive recorded pictures the aligned image frame on the screen may be obtained, as known to a person skilled in the art. The necessary calculations and analysis may be provided by executing a corresponding program in a computer system in communication with the display system.

An important aspect of the examples of embodiments of the present invention compensating aberration errors, is the fact that even though the intersecting dotted lines as depicted for example in figure 11 in some sense will reduce the inherited resolution (pixel number) of a vertical line that is to be modulated, the dynamic pixel configuration of the modulator provides the possibilities to redefine the pixel grouping such that the actual number of pixels representing the intersected vertical line is not reduced.

According to another example of embodiment of the present invention, the laser pointing device is an integral part of the projector in the system, and the alignment procedure as described above is an integral part of a start up procedure.

In some applications, it is usually to provide an installation with back-plane projection onto a semi transparent screen. That is, the images are projected from behind the screen the audience is viewing. The alignment procedure as described above may then be an integral part of the installation process itself. According to an example of embodiment of the present invention, when the physical installation of projector and screen in a back-plane system is finished, the alignment as described above is performed once, and the resulting reformatting of each pixel line corresponding to lines in the image is stored in a memory in the system. Whenever an image line is to be displayed, the information related to the geometrical location of this image line on the screen is used to retrieve the pixel format form the memory of this particular line. This information is then used by the system to redefine the electrode structure to accommodate the line with correct alignment and resolution. The alignment information resulting in an actual setting of the arrangement of distribution may be stored in a non- volatile memory in the system. According to an example of embodiment of the system, the setting of the arrangement of distribution is stored in a connected non- volatile memory, where the stored setting is uploaded to the arrangement of distribution at power up of the system.

In another example of embodiment of the present invention, the modulator consists of 4320 individually settable signal electrodes, which together with a grounded electrode grid makes up 4320 electrode line pairs (Ip).

Such a display can scale the image between the most common image formats as follows:

• HDTV (1920 x 1080) - 4 lp/pixel results in 1080 pixels

• HDTV (1280 x 720) - 6 lp/pixels results in 720 pixels

• DVD (720 x 480) - 9 lp/pixels results in 480 pixel

According to yet another example of embodiment of the present invention, the arrangement of distribution is an integral part of the TDG modulator design. The structural features of the arrangement is implemented in the TDG chip, and by providing inputs on the TDG chip for pixels information of an image line to be displayed together with information related to the pixel formation or pixel grouping for this particular image line to be displayed, the TDG chip may accommodate any implementation of a display system according to the present invention.

Claims

C l a i m s :

1.

Scanning line color display system comprising a Tunable Diffraction Grating (TDG) light modulator having a pixel array structure constituted by grouping of electrodes providing corresponding diffraction gratings on a surface of a gel or membrane (elastomer, polymer) in the TDG modulator when voltages are applied on the electrodes of the groupings, and an image input for images to be displayed by the system, wherein an arrangement of distribution, on basis of pixel format provided by an image currently being applied on the image input, provides the grouping of the electrodes constituting the pixels in the pixel array of the TDG modulator, and wherein the arrangement of distribution provides communication of pixel information from pixels in the image currently to be displayed by the system and driving electronics, thereby providing respective voltage settings on electrodes being members of corresponding pixels.

2.

System according to claim 1, wherein the arrangement of distribution provides the grouping of electrodes according to a user selectable pixel format.

3.

System according to claim 1, wherein the arrangement of distribution further provides the grouping of electrodes according to result of image analysis of an image to be displayed in an image processor running an analysis program, the actual grouping is communicated from the analysis program to the arrangement of distribution.

4.

System according to claim 1,2 or 3, wherein the arrangement of distribution reflects user interaction and/or system interaction on images displayed by the system by partitioning the pixel array, wherein each partitioning have individual pixel resolution as a result of the user interaction and/or the system interaction.

5.

System according to claim 1, 2 or 3, wherein the arrangement of distribution further performs the grouping of electrodes according to an image correction necessary to be performed on images to be displayed, by adjusting the number of electrodes in the pixels individually, thereby providing individual physical length of each grating on the gel or membrane (elastomer, polymer) corresponding to each pixel.

6.

System according to claim 1, wherein the TDG modulator comprise 4320 electrodes, and the arrangement of distribution may provide one of three different pixel array configurations given by: 4 electrodes per pixel resulting in 1080 pixels in the pixel array, 6 electrodes per pixel resulting in 720 pixels in the pixel array, 9 electrodes per pixel resulting in 480 pixels in the pixel array.

7.

System according to claim 1, wherein the TDG modulator comprise n electrodes, the arrangement of distribution support grouping of electrodes as n! combinations of electrodes.

System according to any claim 1 to 6, wherein electrodes in each pixel grouping receives individual voltage settings from the corresponding driving electronics, thereby providing sub pixel modulation of pixels, thereby enhancing grey level resolution of the pixels.

9.

System according to any claim 1 to 8, wherein the arrangement of distribution perform the electrode grouping according to a provided pixel format corresponding to a first image line to be displayed, and after the displaying of the first image line terminates, redistribute the grouping of the electrodes to provide a format for a second image line to be displayed such that the corresponding pixels in the regrouped pixel array appears shifted ¹A pixel in the pixel array direction relative to the first line.

10.

System according to claim 9, wherein an analysis program running in an image processor calculates pixel information to be used in the first image line and second image line based on a same original image line, thereby providing a doubling of pixel resolution in displaying the original image line.

11.

System according to claim 1, wherein a camera receives information about alignment of a screen the system is using to display images on, and wherein the camera communicates such alignment information to the system enabling the arrangement of distribution to dynamically adjust each image line by altering a corresponding physical length of the pixel array constituting the present image line to be displayed, thereby counteracting any misalignment of projection optics of the system or the projection system itself.

12.

System according to claim 11, wherein the alignment information is provided as a difference between an image plane of the camera that is properly aligned and a contour of the screen.

13.

System according to claim 11, wherein the alignment information is provided by camera images of three different points on the screen defined by a laser pointer pointed onto three corners of the screen.

14.

System according to any claim 1, wherein color display functionality of the system is provided by using three TDG modulators, one for each of red, green and blue colors, respectively, and by mixing the colors in projection optics of the system.

15.

System according to any claim 1, wherein color display functionality of the system is provided by using a single TDG modulator comprising three parallel pixel arrays, one for each of red, green and blue colors respectively, and by mixing the colors in projection optics of the system.

16.

System according to claim 1, wherein the arrangement of distribution performs groupings of electrodes such that the total physical length of the pixel array is the same as the physical length provided before the grouping was performed.

17.

System according to claim 1, wherein the arrangement of distribution performs groupings of electrodes such that the total physical length of the pixel array is different from the physical length provided before the grouping was performed.

18.

System according to any claim, wherein the arrangement of distribution is a program running in an image processor constituting a distribution function that is capable of instructing assigned hardware to provide correct application of pixel information onto the corresponding groupings of electrodes and associated driving electronics.

19.

System according to claim 1, wherein the arrangement of distribution comprise a plurality of pixel memory structures wherein each of the plurality of pixel memory structures are connected via driving electronics to separate electrodes in the TDG modulator.

20.

System according to claim 1, wherein an actual setting of the arrangement of distribution is saved after user interaction in a non- volatile memory, thereby using this setting as a default setting of the arrangement of distribution by uploading the setting from the non- volatile memory at power up of the system.

21.

System according to claim 1, wherein the arrangement of distribution selects electrodes for each pixel such that the number of pixel D arise providing a varying respective grating size that compensate for errors introduced in the image when projecting images onto a 180° cylindrical projection screen.

22.

TDG modulator to be used in a line scanning projection display system comprising an arrangement of distribution of pixel information according to claim 1.