The present application relates to improvements to display layouts and specifically to improved color pixel arrangements and means of addressing used in additive electronic projectors, subtractive flat panel displays, and Cathode Ray Tubes (CRT).
Graphic rendering techniques have been developed to improve the image quality of subpixelated flat panels. Benzschawel, et al. in U.S. Pat. No. 5,341,153 teach how to reduce an image of a larger size down to a smaller panel. In so doing, Benzschawel, et al. teach how to improve image quality using a technique now known in the art as “sub-pixel rendering”. More recently Hill, et al. in U.S. Pat. No. 6,188,385 teach how to improve text quality by reducing a virtual image of text, one character at a time, using the very same sub-pixel rendering technique. In a provisional patent application filed by the same inventor, “CONVERSION OF RGB PIXEL FORMAT DATA TO PENTILE MATRIX PIXEL DATA FORMAT” (Ser. No. 60/290,086; Attorney Docket No. CLRV-003P), now U.S. Patent Publication No. 2003/0034992, hereby incorporated by reference, methods were disclosed to generate subpixel rendering filter kernels for improved display formats, including those formats disclosed herein. Prior art projectors, subtractive flat panel displays, and CRTs can not take advantage of such subpixel rendering.
The present state of the art color imaging matrix, for electronic projectors, subtractive color displays and CRT, use a simple orthogonal grid of square pixels aligned in columns and rows as illustrated in prior art
Full color perception is produced in the eye by three-color receptor nerve cell types called cones. The three types are sensitive to different wavelengths of light: long, medium, and short (“red”, “green”, and “blue” respectively). The relative density of the three differs significantly from one another. There are slightly more red receptors than green. There are very few blue receptors compared to red or green.
The human vision system processes the information detected by the eye in several perceptual channels: luminance, chrominance, and motion. Motion is only important for flicker threshold to the imaging system designer. The luminance channel takes the input from only the red and green receptors. It is “color blind”. It processes the information in such a manner that the contrast of edges is enhanced. The chrominance channel does not have edge contrast enhancement. Since the luminance channel uses and enhances every red and green receptor, the resolution of the luminance channel is several times higher than the chrominance channels. The blue receptor contribution to luminance perception is negligible. The luminance channel acts as a resolution band pass filter. Its peak response is at 35 cycles per degree (cycles/°). It limits the response at 0 cycles/° and at 50 cycles/° in the horizontal and vertical axis. This means that the luminance channel can only tell the relative brightness between two areas within the field of view. It cannot tell the absolute brightness. Further, if any detail is finer than 50 cycles/°, it simply blends together. The limit in the diagonal axis is significantly lower.
The chrominance channel is further subdivided into two sub-channels, to allow us to see full color. These channels are quite different from the luminance channel, acting as low pass filters. One can always tell what color an object is, no matter how big it is in our field of view. The red/green chrominance sub-channel resolution limit is at 8 cycles/°, while the yellow/blue chrominance sub-channel resolution limit is at 4 cycles/°. Thus, the error introduced by lowering the blue resolution by one octave will be barely noticeable by the most perceptive viewer, if at all, as experiments at Xerox and NASA, Ames Research Center (R. Martin, J. Gille, J. Larimer, “Detectability of Reduced Blue Pixel Count in Projection Displays”, SID Digest 1993) have demonstrated.
The luminance channel determines image details by analyzing the spatial frequency Fourier transform components. From signal theory, any given signal can be represented as the summation of a series of sine waves of varying amplitude and frequency. The process of teasing out, mathematically, these sine-wave-components of a given signal is called a Fourier Transform. The human vision system responds to these sine-wave-components in the two-dimensional image signal.
Color perception is influenced by a process called “assimilation” or the Von Bezold color blending effect. This is what allows separate color subpixels (or pixels or emitters) of a display to be perceived as the mixed color. This blending effect happens over a given angular distance in the field of view. Because of the relatively scarce blue receptors, this blending happens over a greater angle for blue than for red or green. This distance is approximately 0.25° for blue, while for red or green it is approximately 0.12°. This blending effect is directly related to the chrominance sub-channel resolution limits described above. Below the resolution limit, one sees separate colors, above the resolution limit, one sees the combined color.
An important aspect of electronic displays is resolution. There are three components of resolution in digitized and pixilated displays: bit depth, addressability, and Modulation Transfer Function (MTF). Bit depth refers to the number of displayable brightness or color levels at each pixel location in binary (base 2) power notation. Addressability refers to the number of independent locations that information may be presented and perceived by the human eye. Modulation Transfer Function refers to the number of simultaneously displayable lines and spaces that may be displayed and perceived by the human eye without color error. In display systems that are addressability-limited, the MTF is half of the addressability. However, MTF may be less than half the addressability, given the system design or limitations in the ability of the human eye to perceive the displayed resolution.
Examining the prior art display in
Thus, the prior art arrangement of overlapping the three colors exactly coincidentally, with the same spatial resolution is shown to be a poor match to human vision.
A method for forming a multipixel image on an imaging surface is disclosed. The method comprises projecting for each pixel in the multipixel image a plurality of monochrome beams of different colors towards the imaging surface. Each of the plurality of monochrome beams for each pixel is directed along a path towards the imaging surface, such that images formed on the imaging surface from each beam are convergent by substantially less than about 100%.
A method for forming a multipixel image on a projection screen is disclosed. The method comprises projecting for each pixel in the multipixel image a plurality of monochrome light beams of different colors towards the projection screen. Each of the plurality of monochrome light beams for each pixel is directed along a path towards the projection screen, such that images formed on the projection screen from each light beam are convergent by substantially less than about 100%.
A method for forming a multipixel image on a phosphor surface is disclosed. The method comprises projecting for each pixel in the multipixel image a plurality of electron beams that pass through aperture masks towards the phosphorous surface, each beam exciting substantially separate color emitting phosphors. Each of the plurality of monochrome electron beams for each pixel is directed along a path towards the phosphor surface, such that images formed on the phosphor surface from each electron beam are convergent by substantially less than about 100%.
An optical projector is also disclosed. The optical projector comprises a plurality of monochrome light beams of different colors. Each of the plurality of monochrome light beams for each pixel are directed along a path towards a projection screen. The images formed on the projection screen from each light beam are convergent by substantially less than about 100%.
A CRT video display is also disclosed. The CRT video display comprises a plurality of electron beams. Each of the plurality of electron beams for each pixel are directed along a path towards a phosphor surface. The images formed on the phosphor surface from each electron beam are convergent by substantially less than about 100%.
Referring now to the figures, wherein like elements are numbered alike:
Those of ordinary skill in the art will realize that the following description of the present invention is illustrative only and not in any way limiting. Other embodiments of the invention will readily suggest themselves to such skilled persons.
The prior art overlaps the three colors' images exactly coincidentally, with the same spatial resolution. Here, the color imaging planes are overlaid upon each other with an offset of about one-half pixel. By offsetting the color imaging planes, a display having higher resolution images is created by increasing the addressability of the system. Additionally, the Modulation Transfer Function (MTF) is increased to better match the design to human vision.
A similar procedure is used with a Cathode Ray Tube (CRT) video display, as illustrated in prior art
In contrast, another embodiment is illustrated in
In each of the imaging devices discussed above, the beams (or panels) are convergent by substantially less than about 100%, with less than about 75% preferred, and with about 50% more preferred. In one embodiment, the geometric center of each of the beams (or panels) can lie along a locus of points describing a monotonic function. A monotonic function is always strictly increasing or strictly decreasing, but never both. In its simplest form, the monotonic function can be a straight line.
One advantage of the three-color plane array is improved resolution of color displays. This occurs since only the red and green pixels (or emitters) contribute significantly to the perception of high resolution in the luminance channel. Offsetting the pixels allows higher perceived resolution in the luminance channel. The blue pixel can be reduced without affecting the perceived resolution. Thus, reducing the number of blue pixels reduces costs by more closely matching human vision.
The multipixel image 22 of
The logical pixel 24 of
Images 52 and 68 are built up by overlapping logical pixels as shown in
For projected image or subtractive color flat panel displays, the present application discloses using the same pixel rendering techniques and human vision optimized image reconstruction layout. However, a smoother image construction is created in the present application due to the overlapping nature of the pixels. For an example of a multipixel image 52 having the smoother image construction,
In moving the vertical line, the amount of improvement is proportional to the amount out of phase. Having the images out of phase at a value of substantially less than about 100% is preferred, with less than about 75% more preferred, and with the images being exactly out of phase by about one-half pixel, or about 50%, is ideal.
The central red pixels 76 of the two vertical lines 69 are offset from the central green pixels 70 when superimposed as in
The outer edges, those not adjoining the other line, have the same sequence of brightness levels as described for the case of
The space between the two central vertical lines 69 has three series of smaller diamonds 90 and 94. The overlap of red central line pixels 76 and green interstitial pixels 74, and the overlap of green central line pixels 70 and red interstitial pixels 80, respectively, form a series of smaller diamonds 90 at 50% brightness. The overlap of interstitial pixels 74 and 80 form a series of smaller diamonds 94 at 25% brightness. Theoretically, this represents samples of a sine wave at the Nyquist limit, exactly in phase with the samples. However, when integrating over an imaginary vertical line segment as it moves across from peak to trough to peak, the function is that of a triangle wave. Yet, with the MTF of the projection lens limiting the bandpass of the projected image, the function is that of a smooth sine wave. The display effectively removes all Fourier wave components above the reconstruction point Nyquist limit. Note that the modulation depth is 50%. As long as this is within the human viewer's Contrast Sensitivity Function (CSF) for a given display's contrast and resolution, this modulation depth is visible.
These optical and mechanical means for shifting the color image planes can be used to improve display systems that use prior art arrangements 100 of pixels as illustrated in
In examining the example of a logical pixel 114, 116, and 118 shown in
In examining the vertical line 112 displayed in
In examining and evaluating the display system, it can be noted that while the addressability of the display has been doubled in each axis, the MTF has been increased by a lesser degree. The highest spatial frequency that may be displayed on the modified system is about one-half octave higher than the prior art system. Thus, the system may display 2.25 times more information on four times as many addressable points.
In the above systems the blue information has been ignored for clarity. This is possible due to the poor blue resolving power of human vision. However, in so far as the blue filter or other blue illumination system is less than perfect and allows green light that will be sensed by the green sensing cones of human vision, the blue image will be sensed by the green cones and add to the perception of brightness in the luminance channel. This may be used as an advantage by keeping the blue pixels in registration with the red pixels to add to the red brightness and to offset the slight brightness advantage that green light has in the luminance channel. Thus, the red output pixels may be, in fact, a magenta color to achieve this balance of brightness.
If a system were designed in which the “blue” image has significant leakage of green, and possibly yellow or even red, the “blue” image may be used to further increase the effective resolution of a display. The “blue” color may be closer to a pale pastel blue, a cyan, a purple, or even a magenta color. An example of such a display 126 is illustrated in
Any system that traditionally uses converged, overlapped color pixels can take advantage of the concepts taught herein. For example, a color CRT display used for computer monitor, video, or television display may also be improved by shifting the color components and applying appropriate subpixel rendering algorithms and filters. A simple and effective change for computer monitors is to shift the green electron spot as described above for
The displacement of the multi-color display imaging planes by a percentage of a pixel creates a display of higher resolution images by increasing the addressability of the system. Additionally, the MTF is increased to better match the design to human vision. A projector system using three separate panels can be optimized to better match the human vision system with respect to each of the primary colors. These results can be achieved in a single panel, field sequential color projector using an inclined plane chromodispersive lens element.
While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
The present application claims the benefit of the date of U.S. Provisional Patent Application Ser. No. 60/290,088, entitled “Pentile Matrix 3 Projector”, filed on May 9, 2001 and of the date of U.S. Provisional Patent Application Ser. No. 60/301,088, entitled “Improvements to Color Display Pixel Arrangements and Addressing Means”, filed on Jun. 25, 2001, which are incorporated by reference herein in their entirety.
Number | Name | Date | Kind |
---|---|---|---|
4439759 | Fleming et al. | Mar 1984 | A |
4593978 | Mourey et al. | Jun 1986 | A |
4737843 | Spencer | Apr 1988 | A |
4946259 | Matino et al. | Aug 1990 | A |
5010413 | Bahr | Apr 1991 | A |
5062057 | Blacken et al. | Oct 1991 | A |
5189404 | Masimo et al. | Feb 1993 | A |
5196924 | Lumelsky et al. | Mar 1993 | A |
5233385 | Sampsell | Aug 1993 | A |
5291102 | Washburn | Mar 1994 | A |
5416890 | Beretta | May 1995 | A |
5436747 | Suzuki | Jul 1995 | A |
5438649 | Ruetz | Aug 1995 | A |
5448652 | Vaidyanathan et al. | Sep 1995 | A |
5450216 | Kasson | Sep 1995 | A |
5477240 | Huebner et al. | Dec 1995 | A |
5485293 | Robinder | Jan 1996 | A |
5642176 | Abukawa et al. | Jun 1997 | A |
5648793 | Chen | Jul 1997 | A |
5689283 | Shirochi | Nov 1997 | A |
5719639 | Imamura | Feb 1998 | A |
5724442 | Ogatsu et al. | Mar 1998 | A |
5731818 | Wan et al. | Mar 1998 | A |
5739802 | Mosier | Apr 1998 | A |
5742709 | Ueno et al. | Apr 1998 | A |
5754163 | Kwon | May 1998 | A |
5815101 | Fonte | Sep 1998 | A |
5880707 | Aratani | Mar 1999 | A |
5899550 | Masaki | May 1999 | A |
5917556 | Katayama | Jun 1999 | A |
5929843 | Tanioka | Jul 1999 | A |
5933253 | Ito et al. | Aug 1999 | A |
5971546 | Park | Oct 1999 | A |
6054832 | Kunzman et al. | Apr 2000 | A |
6064363 | Kwon | May 2000 | A |
6069670 | Borer | May 2000 | A |
6115081 | Hirata et al. | Sep 2000 | A |
6151001 | Anderson et al. | Nov 2000 | A |
6160535 | Park | Dec 2000 | A |
6225967 | Hebiguchi | May 2001 | B1 |
6262710 | Smith | Jul 2001 | B1 |
6278434 | Hill et al. | Aug 2001 | B1 |
6297826 | Semba et al. | Oct 2001 | B1 |
6326981 | Mori et al. | Dec 2001 | B1 |
6348929 | Acharya et al. | Feb 2002 | B1 |
6360008 | Suzuki et al. | Mar 2002 | B1 |
6360023 | Betrisey et al. | Mar 2002 | B1 |
6393145 | Betrisey et al. | May 2002 | B2 |
6396505 | Lui et al. | May 2002 | B1 |
6407830 | Keithley et al. | Jun 2002 | B1 |
6414719 | Parikh | Jul 2002 | B1 |
6441867 | Daly | Aug 2002 | B1 |
6469766 | Waterman et al. | Oct 2002 | B2 |
6483518 | Perry et al. | Nov 2002 | B1 |
6509904 | Lam | Jan 2003 | B1 |
6536904 | Kunzman | Mar 2003 | B2 |
6538742 | Ohsawa | Mar 2003 | B1 |
6570584 | Cok et al. | May 2003 | B1 |
6600468 | Kim et al. | Jul 2003 | B1 |
6600495 | Boland et al. | Jul 2003 | B1 |
6608632 | Daly et al. | Aug 2003 | B2 |
6624828 | Dresevic et al. | Sep 2003 | B1 |
6661429 | Phan | Dec 2003 | B1 |
6674436 | Dresevic et al. | Jan 2004 | B1 |
6681053 | Zhu | Jan 2004 | B1 |
6714206 | Martin et al. | Mar 2004 | B1 |
6738526 | Betrisey et al. | May 2004 | B1 |
6750875 | Keely, Jr. et al. | Jun 2004 | B1 |
6781626 | Wang | Aug 2004 | B1 |
6801220 | Greier et al. | Oct 2004 | B2 |
6804407 | Weldy | Oct 2004 | B2 |
6819064 | Nakanishi | Nov 2004 | B2 |
6833890 | Hong et al. | Dec 2004 | B2 |
6836300 | Choo et al. | Dec 2004 | B2 |
6850294 | Roh et al. | Feb 2005 | B2 |
6856704 | Gallagher et al. | Feb 2005 | B1 |
6867549 | Cok et al. | Mar 2005 | B2 |
6885380 | Primerano et al. | Apr 2005 | B1 |
6888604 | Rho et al. | May 2005 | B2 |
6897876 | Murdoch et al. | May 2005 | B2 |
6903378 | Cok | Jun 2005 | B2 |
7110012 | Messing et al. | Sep 2006 | B2 |
7123277 | Brown Elliott et al. | Oct 2006 | B2 |
7167275 | Fukasawa | Jan 2007 | B2 |
20010048764 | Betrisey et al. | Dec 2001 | A1 |
20010052897 | Nakano et al. | Dec 2001 | A1 |
20020012071 | Sun | Jan 2002 | A1 |
20020093476 | Hill et al. | Jul 2002 | A1 |
20020122160 | Kunzman | Sep 2002 | A1 |
20020136293 | Washino | Sep 2002 | A1 |
20020149598 | Greier et al. | Oct 2002 | A1 |
20020180745 | Matsuda et al. | Dec 2002 | A1 |
20020191130 | Liang et al. | Dec 2002 | A1 |
20030034992 | Brown Elliott et al. | Feb 2003 | A1 |
20030071826 | Goertzen | Apr 2003 | A1 |
20030071943 | Choo et al. | Apr 2003 | A1 |
20030214635 | Asakura et al. | Nov 2003 | A1 |
20030218618 | Phan | Nov 2003 | A1 |
20040008208 | Dresvic et al. | Jan 2004 | A1 |
20040021804 | Hong et al. | Feb 2004 | A1 |
20040061710 | Messing et al. | Apr 2004 | A1 |
20040085495 | Roh et al. | May 2004 | A1 |
20040095521 | Song et al. | May 2004 | A1 |
20040108818 | Cok et al. | Jun 2004 | A1 |
20040114046 | Lee et al. | Jun 2004 | A1 |
20040150651 | Phan | Aug 2004 | A1 |
20040155895 | Lai | Aug 2004 | A1 |
20040169807 | Rho et al. | Sep 2004 | A1 |
20040179160 | Rhee et al. | Sep 2004 | A1 |
20040189662 | Frisken et al. | Sep 2004 | A1 |
20040189664 | Frisken et al. | Sep 2004 | A1 |
20040232844 | Brown Elliott | Nov 2004 | A1 |
20040233308 | Elliott et al. | Nov 2004 | A1 |
20040239813 | Klompenhouwer | Dec 2004 | A1 |
20040239837 | Hong et al. | Dec 2004 | A1 |
20040263528 | Murdoch et al. | Dec 2004 | A1 |
20050007539 | Taguchi et al. | Jan 2005 | A1 |
20050024380 | Lin et al. | Feb 2005 | A1 |
20050031199 | Ben-Chorin et al. | Feb 2005 | A1 |
20050040760 | Taguchi et al. | Feb 2005 | A1 |
20050068477 | Shin et al. | Mar 2005 | A1 |
20050082990 | Elliott | Apr 2005 | A1 |
20050083356 | Roh et al. | Apr 2005 | A1 |
20050094871 | Berns et al. | May 2005 | A1 |
20050099426 | Promerano et al. | May 2005 | A1 |
20050140634 | Takatori | Jun 2005 | A1 |
20050151752 | Phan | Jul 2005 | A1 |
20050162600 | Rho et al. | Jul 2005 | A1 |
20050169551 | Messing et al. | Aug 2005 | A1 |
Number | Date | Country |
---|---|---|
197 46 329 | Mar 1999 | DE |
299 09 537 | Oct 1999 | DE |
199 23 527 | Nov 2000 | DE |
199 23 527 | Nov 2000 | DE |
201 09 354 | Sep 2001 | DE |
0 671 650 | Sep 1995 | EP |
0 793 214 | Sep 1997 | EP |
0 878 969 | Nov 1998 | EP |
0 899 604 | Mar 1999 | EP |
1 083 539 | Mar 2001 | EP |
03-78390 | Apr 1991 | JP |
06-214250 | Aug 1994 | JP |
2002215082 | Jul 2002 | JP |
2004 078218 | Mar 2004 | JP |
2004004822 | Aug 2004 | JP |
WO 0021067 | Apr 2000 | WO |
WO 0042564 | Jul 2000 | WO |
WO 0042762 | Jul 2000 | WO |
WO 0045365 | Aug 2000 | WO |
WO 0065432 | Nov 2000 | WO |
WO 0067196 | Nov 2000 | WO |
WO 0110112 | Feb 2001 | WO |
WO 0152546 | Jul 2001 | WO |
WO 02059685 | Aug 2002 | WO |
WO 03050605 | Feb 2003 | WO |
WO 03056383 | Jul 2003 | WO |
WO 2004017129 | Feb 2004 | WO |
WO 2004021323 | Mar 2004 | WO |
WO 2004027503 | Apr 2004 | WO |
WO 2004040548 | May 2004 | WO |
WO 2004086128 | Oct 2004 | WO |
WO 2005050296 | Jun 2005 | WO |
Number | Date | Country | |
---|---|---|---|
20050104908 A1 | May 2005 | US |
Number | Date | Country | |
---|---|---|---|
60301088 | Jun 2001 | US | |
60290088 | May 2001 | US |