WO2006036200A1 - Tube cathodique de tvhd a balayage vertical et son procede d'utilisation - Google Patents

Tube cathodique de tvhd a balayage vertical et son procede d'utilisation Download PDF

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Publication number
WO2006036200A1
WO2006036200A1 PCT/US2005/011397 US2005011397W WO2006036200A1 WO 2006036200 A1 WO2006036200 A1 WO 2006036200A1 US 2005011397 W US2005011397 W US 2005011397W WO 2006036200 A1 WO2006036200 A1 WO 2006036200A1
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WO
WIPO (PCT)
Prior art keywords
ray tube
cathode ray
electron beams
tube system
crt
Prior art date
Application number
PCT/US2005/011397
Other languages
English (en)
Inventor
Istvan Gorog
Robert Lloyd Barbin
Richard Hugh Miller
Rainer Schweer
Original Assignee
Thomson Licensing
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Publication of WO2006036200A1 publication Critical patent/WO2006036200A1/fr

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Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G1/00—Control arrangements or circuits, of interest only in connection with cathode-ray tube indicators; General aspects or details, e.g. selection emphasis on particular characters, dashed line or dotted line generation; Preprocessing of data
    • G09G1/06—Control arrangements or circuits, of interest only in connection with cathode-ray tube indicators; General aspects or details, e.g. selection emphasis on particular characters, dashed line or dotted line generation; Preprocessing of data using single beam tubes, e.g. three-dimensional or perspective representation, rotation or translation of display pattern, hidden lines, shadows
    • G09G1/14—Control arrangements or circuits, of interest only in connection with cathode-ray tube indicators; General aspects or details, e.g. selection emphasis on particular characters, dashed line or dotted line generation; Preprocessing of data using single beam tubes, e.g. three-dimensional or perspective representation, rotation or translation of display pattern, hidden lines, shadows the beam tracing a pattern independent of the information to be displayed, this latter determining the parts of the pattern rendered respectively visible and invisible
    • G09G1/16—Control arrangements or circuits, of interest only in connection with cathode-ray tube indicators; General aspects or details, e.g. selection emphasis on particular characters, dashed line or dotted line generation; Preprocessing of data using single beam tubes, e.g. three-dimensional or perspective representation, rotation or translation of display pattern, hidden lines, shadows the beam tracing a pattern independent of the information to be displayed, this latter determining the parts of the pattern rendered respectively visible and invisible the pattern of rectangular co-ordinates extending over the whole area of the screen, i.e. television type raster
    • G09G1/165—Details of a display terminal using a CRT, the details relating to the control arrangement of the display terminal and to the interfaces thereto
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
    • H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
    • H04N3/16—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by deflecting electron beam in cathode-ray tube, e.g. scanning corrections
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
    • H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
    • H04N3/16—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by deflecting electron beam in cathode-ray tube, e.g. scanning corrections
    • H04N3/22—Circuits for controlling dimensions, shape or centering of picture on screen
    • H04N3/23—Distortion correction, e.g. for pincushion distortion correction, S-correction
    • H04N3/233—Distortion correction, e.g. for pincushion distortion correction, S-correction using active elements
    • H04N3/2335—Distortion correction, e.g. for pincushion distortion correction, S-correction using active elements with calculating means

Definitions

  • the invention relates to a cathode ray tube (CRT) for a High Definition Television (HDTV) display operating in a vertical scan mode and a method of operating the CRT.
  • CTR cathode ray tube
  • HDTV High Definition Television
  • HDTV High definition television
  • demand has prompted an increase in demand for larger aspect ratio, true flat screen displays having a shallower depth, increased deflection angle and improved visual resolution performance.
  • FIG. 1 illustrates the basic geometrical relationship between throw distance and deflection angle for a typical CRT. Increasing the deflection angle (A) reduces the throw distance, thus allowing for production of a shorter CRT and ultimately, a slimmer television set.
  • obliquity is defined as the effect of a beam intercepting the screen at an oblique angle, thereby causing an elongation of the spot.
  • the problem of obliquity becomes especially apparent in CRTs having a standard horizontal gun orientation, i.e., a CRT whose guns have a horizontal alignment along the major axis of the screen.
  • a spot having a generally circular shape at the center of the screen becomes oblong or elongated as the spot moves toward edges of the screen.
  • the spot appears most elongated at the edges of the major axis and at the screen corners.
  • the obliquity effect causes the spot size to grow.
  • the following equation defines the spot size radius SS ra diai:
  • CRT's typically include a horizontal yoke that generates a pincushion shaped field and a vertical yoke that generates a barrel shaped field. These yoke fields cause the spot shape to become elongated. This elongation adds to the obliquity effect by further increasing spot distortion at the three-o'clock and nine o'clock positions (referred to as the "3/9" positions) and at corner positions on the screen.
  • U.S. Patent No. 5, 170,102 describes a CRT with a vertical electron gun orientation whose undeflected beams appear parallel to the short axis of the display screen.
  • the deflection system described in this patent includes a signal generator for causing scanning of the display screen in a raster-scan fashion, thereby yielding a plurality of lines oriented along the short axis of the display screen.
  • the deflection system also comprises a first set of coils for generating a substantially pincushion-shaped deflection field for deflecting the beams in the direction of the short axis of the display screen.
  • a second set of coils generates a substantially barrel shaped deflection field for deflecting the beams in the direction in the long axis of the display screen.
  • the deflection system's coils generally distort spots by elongating them vertically. This vertical elongation compensates for obliquity effects, thereby reducing spot distortion at the 3/9 and corner positions on the screen.
  • the barrel shaped field required -A- to achieve self convergence at 3/9 screen locations overcompensates for obliquity and vertically elongates the spot at the 3/9 and corner locations as shown in Figure 10 of the U.S. Patent No. 5, 170,102.
  • a cathode ray tube and a method of operating the cathode ray tube for a display system which has a picture display area and an electron gun assembly with inline guns being aligned vertically.
  • the display system includes a deflection system for the cathode ray tube to provide line rate scanning in a vertical direction.
  • a video signal processing system serves to transpose video signals supplied to the deflection system.
  • the deflection system includes a first picture correction circuit for reducing picture distortion in at least part of the picture display area.
  • the video signal processing system also includes a second correction circuit for reducing picture distortion in at least of part of picture display area coextensive with the part of the picture display area in which the first picture correction circuit reduces picture distortion.
  • FIGURE 1 is a diagram depicting the basic geometrical relationship between the throw distance and deflection angle in a typical CRT;
  • FIGURE 2 is a diagrammatic cross sectional view of a CRT according to an embodiment of the present principles
  • FIGURE 3 is a diagram of the screen of the CRT of FIG. 2 illustrating a mis- convergence pattern in accordance with the present principles
  • FIGURE 4 is a diagram depicting optimization of spot shape in accordance with the present principles
  • FIGURE 5 is a block diagram of a first illustrative embodiment of the associated signal processing and-electronic drive system-for driving the CRT of FIG. 2 in accordance with the present principles in accordance with the present principles
  • FIGURE 6 is a block diagram of a second illustrative embodiment of the associated signal processing and electronic drive system for driving the CRT of FIG. 2 in accordance with the present principles
  • FIGURE 7 is a block diagram of a third illustrative embodiment of the associated signal processing and electronic drive system in accordance with the present principles
  • FIGURE 8 is a block diagram of a modification of the CRT display system shown of
  • FIG. 6 is a diagrammatic representation of FIG. 6
  • FIGURE 9 is a block diagram showing a second modification of the CRT display system of FIG. 6.
  • FIGURE 10 is a diagram depicting a portion of a CRT display screen subject to image distortion;
  • FIGURE 11 is a block diagram of a video correction system within the CRT display system of FIGS. 5-9; and FIGURE 12 is a characteristic graph for a polyphase filter within the video correction system of FIG. i l.
  • FIG. 2 illustrates a cathode ray tube (CRT) 1 , for example a W76 wide screen tube, having a glass envelope 2 comprising a rectangular faceplate panel 3 and a tubular neck 4 connected by a funnel 5.
  • the funnel 5 has - an internal conductive coating (not shown) that extends from an anode button 6 toward the faceplate panel 3 and to the neck 4.
  • the faceplate panel 3 comprises a viewing faceplate 8 and a peripheral flange or sidewall 9, which is sealed to the funnel 5 by a glass frit 7.
  • the inner surface of the faceplate panel 3 carries a three-color phosphor screen 12.
  • the screen 12 comprises a line screen with the phosphor lines arranged in triads. Each triad includes a phosphor line of three primary colors, typically Red, Green and Blue, and extends generally parallel to the major axis of the screen 12.
  • a mask assembly 10 lies in a predetermined spaced relation with the screen 12. The mask assembly 10 has a multiplicity of elongated slits extending generally parallel to the major axis of the screen 12.
  • An electron gun assembly 13, shown schematically by dashed lines in Figure 2 is centrally mounted within the neck 4 to generate three inline electron beams, a center beam and two side or outer beams, directed along convergent paths through the mask assembly 10 to strike the screen 12.
  • the electron gun assembly 13 has three vertically oriented guns, each generating an electron beam for a separate one of the three colors, Red, Green and Blue.
  • the three guns lie in a linear array extending parallel to a minor axis of the screen 12.
  • the CRT 1 employs an external magnetic deflection system comprised of a yoke 14 situated in the neighborhood of the funnel-to-neck junction. When activated with a drive signal in a manner discussed hereinafter, the yoke 14 generates magnetic fields that cause the beams to scan over the screen 12 vertically and horizontally in a rectangular raster.
  • the external magnetic system or electronic deflection system can be driven by drive circuits and applies a high frequency deflection in a short direction to electron beams emitted from the electron guns of the electron gun assembly 13.
  • the electron beam undergoes spot shaping.
  • spot shaping a discussion of the yoke 14 and the effect of the yoke fields will prove helpful.
  • the yoke 14 lies in the neighborhood of the funnel-to- neck junction on the CRT 1 as shown in Figure 2.
  • the yoke 14 has first deflection coil system (not shown) that generates a horizontal deflection yoke field that is substantially barrel-shaped.
  • the yoke 14 has a second deflection coil system (not shown) electrically insulated from the first deflection coil system for generating a vertical yoke field that is substantially pincushion-shaped.
  • the horizontal barrel field shape associated with the first deflection system undergoes an adjustment (e.g., a reduction), to yield an optimized spot shape at the sides of the screen.
  • the barrel shape of the yoke field attributable to the second deflection coil system undergoes a reduction.
  • the combined effects of the barrel-shaped field and the dynamic astigmatism correction provided by the dynamic focus associated with the electron guns yields an optimized, nearly round spot shape at the 3/9 position and at the corner screen locations.
  • the use of pincushion vertical field and a barrel horizontal field, where the barrel horizontal field is adjusted to improve spot shapes and allow some misconvergence of the electron beams along the screen edges is characterized as quasi- self-convergent deflection fields.
  • FIGURE 3 illustrates a display screen showing the resulting misconvergence from such a reduced barrel-shaped field.
  • Overconvergence refers to a condition that results from the red and blue beams crossing over each other prior to striking the screen. The amount of overconvergence varies as a function beam deflection. Thus, the resultant pattern appears converged at the center of the screen while appearing mis-converged at the sides of the screen.
  • the overconvergence causes the electron beams to generate a blue, green, red convergence pattern at the sides of the screen as seen in FIG. 3.
  • the resultant overconvergence at the screen sides in this example was measured at 15 millimeters.
  • Other CRT designs having different geometries, or different yoke field distributions will result in more or less overeconvergence, for example, in the range of 5 to 35 millimeters.
  • multipole coils such as the quadrupole coils 16 shown in FIG. 2
  • multipole coils can correct for mis-convergence, or over-convergence that results from the yoke effect described above.
  • locating the quadrupole coils 16 on the gun side of the yoke 14 will dynamically correct for the yoke effect.
  • the quadrupole coils 16 are fixed to the yoke 14 or alternatively, can be applied to the neck and have their four poles oriented at approximately 90° angles relative to each other as is known in the art.
  • the resultant magnetrc " fierd”' displaces " the ⁇ outer (red and blue) beamsin a vertical direction to provide correction for the mis-convergence pattern shown in FIG. 3.
  • the quadrupole coils 16 can lie behind the yoke 14 approximately at or near the dynamic astigmatism correction point of the guns of the electron gun assembly 13.
  • the quadrupole coils 16 create a correction field for adjusting miscovergence on the screen.
  • the quadrupole coils 16 in this embodiment are driven in synchronism with the horizontal deflection, i
  • the signal driving the quadrupole coils 16 has a magnitude selected to correct the overconvergence described above.
  • the quadrupole coil signal has a waveform whose shape approximates a parabola.
  • the electron gun assembly 13 of the CRT 1 has electrostatic dynamic focus astigmatism correction to achieve optimum focus in both the horizontal and vertical directions of each of the three beams.
  • This electrostatic dynamic astigmatism correction occurs separately for each, beam, thereby allowing for correction of the horizontal-to-vertical focus voltage differences without affecting convergence.
  • the quadrupole coils 16 affect beam focus, their location near the dynamic astigmatism point of the guns of the electron gun assembly 13 allows for correction of this effect by adjusting the electrostatic dynamic astigmatism voltage so that there is a minimal effect on the spot. This enables correction of misconvergence at selected locations on the screen without affecting the spot shape.
  • modification of the yoke field design can optimize spot shape and the dynamically driven quadrupole coils 16 can correct for any resultant misconvergence.
  • FIGURE 4 illustrates one quadrant of the screen of a W76 CRT with an aspect ratio of
  • the center column of Table 1 lists the spot dimensions for a prior art standard horizontal gun orientation CRT with self-convergent beams, whereas the right-hand column represents the results for a CRT with vertical gun alignment in accordance with the present principles-wherein- the- beams undergo dynamically -controlled convergence.
  • spot shape suffers a slight compromise at the 6 O'clock and 12 O'clock screen positions (6/12 or otherwise as the top and bottom)
  • spot size uniformity shows great improvement at the 3 O'clock and 9 O'clock positions (3/9 or otherwise as the side) and at the corner locations.
  • the present technique advantageously provides more uniform spot shape across the screen, thus enhancing visual resolution.
  • the invention is applicable to CRTs having deflection angles at 100 or above, the invention has particular applicability to much larger deflection angles such as systems exceeding 120 degrees. 2.
  • Table 2 provides a comparison of the clock frequency, scan line count, and pixel per scan line value for a conventional CRT having horizontal aligned electron guns versus a vertical scan CRT display in accordance with the present principles.
  • the visible image field contains 1280 vertical scan lines with 720 addressable points (i.e. 720 pixels/line) on each scan line.
  • the three different scan systems in Table 2 afford excellent visual performance. Any visual differences due to the number of scan lines or pixels appear insignificant on a screen size having a diagonal dimension of less than 1 meter at normal viewing distances of larger than 1 meter.
  • the vertical scan system provides a significantly better image because of the better spot size/resolution of the electron " beam. While the high speed scan frequency remains about the same for all systems, the vertical scan system requires significantly less scan power because the deflection angle in the vertical direction is much smaller-than-hori-zontal-direetion-for a ⁇ 16 x 9 aspect ratio systems.- -Further, the-pixel clock rate for the vertical scan system is much less than the other systems.
  • a particularly advantageous arrangement utilizes 1280 interlaced visual scan lines, which significantly reduces the deflection power requirements with no detrimental effect when displaying HDTV images.
  • the CRT display system of the present principles can operate at scan rates other than those listed in Table 2.
  • a scan rate that yields vertical scan lines in the range of approximately 700 to 3000 for 16:9 format tubes in the diagonal dimensional range between approximately 20 cm and 1 m provide excellent HDTV displays under normal home viewing conditions (approximately 2 meter viewing distance).
  • the CRT display system of the present principles makes use of digital video correction that maps digital video signal information to the appropriate scan location to correct convergence and geometry.
  • This video mapping does not affect the spot shape and affords an effective tool for achieving small corrections.
  • video correction can cause some loss in light output since all the beams must scan all the areas of the screen for the video mapping to work.
  • employing video correction to compensate for the 15 mm of red-to-blue misconvergence shown in FIGURE 3 typically would require an additional overscan of 7.5 mm at the top (for the red) and also at the bottom (for the blue) resulting in a light output loss of about 15/372 or 4% along the sides.
  • a horizontal scan sequence must undergo a change from a conventional left-to-right and stepwise top-to-bottom regimen to a top-to- bottom and stepwise left to right transposed sequence.
  • DOS Digital Orthogonal Scan
  • CRT displays-exhibit raster distortions.
  • the commonest raster distortions pertain to geometric errors and to convergence errors.
  • a geometric error results irom non- linearities in the scanned positions of the beams as the raster traverses the screen .
  • Convergence errors occur in a CRT display when the Red, Green and Blue rasters do not align perfectly such that over some portion of the image, a Red sub-image appears offset with respect to the Green sub-image and the Blue sub-image appears offset to the right of the Green sub-image. Convergence errors of this type can occur in any direction and can appear anywhere in the displayed image.
  • the incoming signal undergoes processing in a manner to actually distort the signal inverse to the distortion inherent in the CRT, then the signal, when displayed, will appear distortion-free.
  • VC performs inverse distortion by displacing the Red sub-image in the opposite direction (e.g., to the right) by the same amount with respect to the Green sub-image to counteract the CRT distortion which effectively displaces the Red Sub-image to the left and similarly displaces the Blue sub-image to the left, resulting in good Red-to-Green convergence.
  • the VC displaces the Blue sub-image to the left, compensating for the CRT convergence distortion.
  • VC can also be used to reshape all sub-images (including the Green sub- image) to reshape the entire overall raster geometry. Further, VC can be used in conjunction with the yoke field to achieved desired raster geometries.
  • IP Image Processing
  • IP operations can be executed in analog or digital forms.
  • the digital form for IP is preferred when digital signals are available in the signal path.
  • the various signal processing tasks associated with DOS, VC and IP operations can be effectively executed in a programmable gate array and associated memory.
  • the programmable gate array can take several alternative forms including field programmable gate arrays (which are commonly referred to as FPGAs), mask programmable gate arrays, and Application-specific Integrated Circuits and other forms of circuits suitable for digital signal processing.
  • FIGS. 5, 6, and 7 illustrate alternate embodiments of a vertical-scan CRT display system that perfo ⁇ ns a combination of DOS, VC, and IP operations in accordance with the present principles. As will become better understood, some embodiments perform one or more of the DOS, VC, and IP operations in the digital domain while other embodiments perform one or more operations in the analog domain.
  • FIG. 5 illustrates a first embodiment of a vertically transposed scan CRT display system in accordance with the present principles.
  • the display system receives input signals from a source such as a Set-Top Box (STB) 100, for example, an RCA Model DTC 210 set top box.
  • STB 100 provides horizontal and vertical progressive sync [H&V(p)Sync] signals and Red, Green, and Blue component analog signals [RGB(p)].
  • DSP Digital Signal Processing
  • Element 110 comprises an analog-to-digital (A/D) converter that converts the RGB( ⁇ ) analog signals into three digital signal arrays for the R, G, and B progressive rasters, respectively.
  • A/D analog-to-digital
  • Element 120 comprises firmware, typically in the form of a programmable gate array that operates on the RGB(p) signal set to perform VC operations described in greater detail with respect to FIGS 10-12.
  • the element 120 could take the form of a programmed processor.
  • the individually corrected R, G, and B arrays typically undergo storage in a memory (not shown) comprising part of the gate array 120.
  • the memory reads out individual R, G and B signals as transposed vertical scan signal (DOS) in an interlaced manner.
  • DOS transposed vertical scan signal
  • the output of the gate array 120 comprises a set of interlaced digital R, G, and B signals.
  • the gate array also provides H and V interlaced sync signals corresponding to the timing associated with the transposed, vertically scanned, interlaced signal format.
  • Element 130 in FIG. 5 comprises a digital-to-analog (D/ A) converter for converting the R, G ,and B signals into corresponding interlaced analog R, G, and B signals, respectively.
  • Element 140 comprises a matrix operator that converts the R, G, and B signals into a YPbPr format through standard matrix operations. Alternatively, the matrix operator 140 could convert the R, G, and B signals to other formats such as YUV or YCbCr.
  • the term - "YPbPr format” includes any type of component signal encoded into -a luminance channel and two color difference channels in either digital or analog form.
  • luminance "RGB” as used herein, refers to the three color field components, whether in digital or analog form.
  • An image processing unit 150 receives the DOS-modified component video from the matrix operator 140.
  • the image processing element 150 performs image processing and optimization operations known in the art, such as edge enhancement. Further, the image processing element 150 possesses the ability to convert the YPbPr format signals back to an RGB format to adjust CRT parameters such as contrast, brightness, Automatic Kine Bias (AKB), and Automatic Beam Limit (ABL).
  • Each of the R, G, and B signals from the image processing element 150 passes to a separate one of a set of video output amplifiers 160 that provides the input signals to the electron gun assembly of the CRT 170.
  • the sync signals produced by the gate array 120 undergo further processing by sync processor 180 prior to input to the dynamic focus element 190 to generate a dynamic focus signal.
  • a quad drive circuit 200 receives the processed sync signals from the sync processor 180 to generate the CRT deflection yoke signals.
  • a deflection signal generator 210 processes the sync signals from the sync processor 180 to generate the H and V signals that drive the deflection coils of CRT 170.
  • FIG. 6 shows an alternative embodiment of a vertical scan CRT display system in accordance with the present principles.
  • a front-end processor element 300 receives incoming HDTV signals and provides a digital video output signal in a progressive scan YPbPr format, The front-end processor 300 also generates horizontal and vertical progressive sync.
  • a transpose operator element 310 receives the output signals from the front-end processor and performs a DOS operation to yield a progressive "vertically scanned YPbPr signal. "
  • An image processor 320 performs image processing on the vertically scanned YPbPr signal. For example, the image processor 320 can perform a basic set of IP functions, such as edge enhancement.
  • a format converter 330 performs YPbPr to RGB format conversion to enable a video correction element 340 to accomplish Video Correction (VC).
  • the video correction element 340 also accomplishes a conversion from progressive to interlaced vertical scanning.
  • the digital RGB(i) interlaced vertical scan signal output by the video correction element 340 undergoes a conversion by a digital-to-analog (D/ A) converter 350 yielding analog RGB(i) signals.
  • An image processor 360 accomplishes final generation of the interlaced vertical scan signal by providing contrast, brightness, AKB, and ABL functions.
  • a video amplifier element 370 drives the three electron guns of CRT 380 in accordance with the RGB(i) signals from the image processor 360.
  • a sync processor 390 provides sync signals to the dynamic focus generator 400, quad drive 410, and deflection signal generator 420 in accordance with the H&V(i) signals received by the sync processor from the video correction element 340.
  • CRT display systems of FIGS. 5 and 6 share common elements, they differ in several ways. Note that the CRT display system of FIG. 5 completes all IP operations after the DOS function and after the incoming signal has undergone Video Correction. The CRT display system of FIG. 6 performs the DOS function followed by Image Processing (IP). Such an arrangement allows for use of an image processor, such as image processor 320, designed to process the DOS signal prior to the VC operation which is especially desirable when VC is utilized for large convergence errors.
  • IP Image Processing
  • FIG. 7 depicts yet another embodiment of a CRT display system in accordance with the present principles.
  • the CRT display system of FIG. 7 includes elements in common with ihe CRT display system of FIG. 6 and like reference numbers reference like elements.
  • the CRT display system of FIG. 6 utilizes a single image processor 320 downstream of the transpose operator element 310.
  • the CRT display system of FIG. 7 employs two image processors 320' and 360'.
  • the first image processor 320' lies downstream of the front end processor 300 and provides pre-processing of the digital YPbPr signals prior to input to the image transpose operator element 310.
  • the second image processor 360' lies downstream of the D/A converter 350 and provides post processing of the interlaced analog RGB(i), as well as setting the brightness, AKB, and ABL.
  • the CRT display system of FIG. 7 operates the same as that of FIG. 6.
  • An advantage can arise by doing some image pre-processing prior to preparing the signals for the specific addressing requirements associated with a particular display.
  • the first image processor 320' performs such pre- processing prior the DOS operation by the transpose operator element 310.
  • the CRT display system of FIG. 7 could include yet another image processor (not shown) residing downstream of the transpose operator element 310 and upstream of the format converter 330.
  • a particular type of image pre-processing of general interest involves the pre- processing of 50 Hz HDTV images for display on a CRT operated in the transposed vertical scan mode.
  • 50 Hz interlaced images commonly undergo conversion into another format.
  • Digital signal processing methods allow conversion from 50 Hz to 60 Hz.
  • the utilization of a pre-processor for accomplishing 50 Hz to 60 Hz conversion would allow the CRT display system of the present principles to operate at 60 Hz worldwide irrespective of whether the incoming signal utilizes a frequency of 50 Hz or 60 Hz.
  • 50 Hz signals often undergo conversion to 75 Hz to eliminate flicker. Such a conversion to 75 Hz could occur within the first image processor 320' in FIG. 7 and the remainder of the display ⁇ " chain, beginning " with " transpose ⁇ operatoreleme ⁇ t-3 lO7could ' operatein"a 75 Hz. mode.
  • FIGURE 8 illustrates yet another embodiment of a CRT display system that optimizes image quality.
  • the CRT display system of FIG. 8 shares elements in common with the display system of FIGS. 6 and 7 and like reference numerals refer to like elements.
  • the CRT display system of FIG. 8 executes a series of image enhancement operations on the final RGB sub-images prior to display on the CRT 380. Common operations of this kind include peaking and edge enhancement by individual colors.
  • the CRT display system of FIG. 8 accomplishes such enhancement by way of image enhancement element 355 situated downstream of the D/A converter 350 and upstream of the image processor 360. By virtue of being downstream from the D/A converter 350, the image enhancement element 355 accomplishes color-by-color post-processing in the analog domain.
  • the enhancement element 355 and the image processor 360 can be characterized as a post-image processing element which sets contrast, brightness, AKB, and ABL and modifies RGB(i) analog signals, whereby at least one of the functions is performed from the group consisting of peaking, black stretch, color stretch and edge enhancement of individual colors.
  • FIGURE 9 depicts an alternative embodiment of a CRT display system, which like the
  • the CRT display system of FIG. 9 provides optimized image quality.
  • the CRT display system of FIG. 9 employs many of the same elements as the display system of FIG 8 and like numbers reference like elements.
  • the CRT display system of FIG. 9 performs such enhancements in the digital domain.
  • the CRT display system of FIG. 9 employs a digital image enhancement element 355' downstream of the Video Correction element 340 and upstream of the D/A converter 350.
  • the enhancement element 355' accomplishes RGB image enhancements in the digital domain. Only after completion of the color by color image enhancements does digital-to-analog conversion take place.
  • the CRT display system of FIG. 9 can include the application of beam scan velocity modulation (BSVM) in the fast veritical scan direction.
  • BSVM constitutes a sharpness enhancement method that involves local changes in the scan velocity of the electron beam based on brightness transitions in the video signal inputs.
  • either the video correction element 340 or the digital enhancement unit 355' could provide a suitable BSVM signal.
  • the CRT comprises a plurality image processors to accomplish image enhancement operations to improve perceived image quality with respect to one or more attributes like edge sharpness, reduce noise, adjust color, and contrast in the displayed image.
  • a first image processor receives an input signal and then feeds the signal to the transposition operation, and such first image processor may be an analog processor operating on an analog component YPbPr signal which, after processing, is fed to an analog-to-digital converter preceding the transposition operation, or such first processor could be a digital circuit operating on a digital component YCbCr signal, in which case first image processor input is either a component digital signal or a component analog signal which is then passed through an analog-to-digital converter which precedes first image processor.
  • a second image processor following the digital transposition operation and preceding the video correction operation is utilized to cause further image enhancements subsequent to the image transposition, such second image processor is implemented in digital circuitry and operates on a transposed component video stream like YCbCr and such second image processor output is fed to a digital matrixing means which converts the digital component-YCbCr signal-to-a-digital RGB-signal, which then-is operated on by the video correction system.
  • a third image processor may be utilized and such third image processor is located in the signal stream subsequent to the video correction operation and such third image processor executes image enhancement operations on the individual RGB transposed and video corrected color signals;
  • such third image processor may be of an analog type, in which case the digital RGB outputs are first converted by a digital-to-analog converter to analog RGB signals, or it may be of a digital type, in which case the digital RGB signals are directly fed to such third image processor and the output of this third image processor is then fed to a digital-to-analog converter whose RGB analog output is then available as input to the final elements in the video chain that drive the CRT and provide the appropriate signal levels to obtain optimized brightness, contrast, beam cut-off, and black level.
  • the CRT display systems of FIGS. 5-9 include video correction performed by the gate array element 120 of FIG. 5 and by the video correction element 340 of FIGS 6-9.
  • the video correction occurs by first determining the geometric raster distortion of each color, and then establishing the necessary horizontal and -vertical displacement (i.e., ⁇ x and ⁇ y) needed to correct the individual raster distortions. Trie video then undergoes displacement by ⁇ x and ⁇ y to correct for such distortions.
  • FIGURE 10 depicts an example of image distortion appearing on a CRT screen.
  • the 1 image appears distorted by the amounts ⁇ x and ⁇ y (shown as ⁇ Vx and ⁇ Vy in the FIG. 10). Note that the distortion over the image is not homogeneous and differs for each color.
  • FIG. 1 1 provides a general overview of video correction for distortion in accordance with the present principles.
  • a measuring device determines the x and y offsets ( ⁇ x and ⁇ y), typically with a grid of 9 x 9 or a 5 x 5 points spaced over the entire image, yielding ⁇ x and ⁇ y offset matrices 400 and 401.
  • the ⁇ x and ⁇ y offset matrices undergo interpolation, via elements 402 and 403 in FIG. 11.
  • the elements 402 and 403 can take the form of a programmed processor, application specific integrated circuit, field programmable gate array or digital signal process as an example.
  • a re-sampling filter 404 re- samples video from an incoming source, such as the progressive RGB(p) signals from the format converter 330 of FIGS. 6-9 or the AfD converter 110 of FIG. 5 to yield a video image 405 that is distorted by an amount inverse to the distortion that arises from the geometric raster distortion of each color.
  • the distortion created by video correction cancels the original distortion, yielding a substantially distortion free-image 406.
  • the horizontal Ax and vertical Ay displacements are measured or computed on a 9x9 grid.
  • the result of the interpolation is a distortion vector comprising integer and non-integer components in both the x and y direction.
  • the re-sampling filter 404 consists of a simple remapping of the pixels for the integer component of the distortion vector and of a polyphase filter for the non-integer component. The remapping is conveniently accomplished by reading out a video source memory with adjusted addresses, whereas the integer part of the above interpolation, typically cubic interpolation, is used for the address adjustment.
  • filter 404 of FIG. 11 can take the form of a five tap polyphase filter as described in graph of FIG. 12.
  • the graph of Fig 12 shows coefficient values on its y-axis and tap values on its x-axis.
  • the polyphase filter adapts its coefficients to the non-integer shift between the original and the final pixels.
  • the non-integer component of the interpolation can assume values between -0.5 and +0.5, corresponding to interpolated pixel positions +/-0.5 sample spaces from the closest integer value.
  • the computed five tap-weights are shown for two non-integer interpolated pixels.
  • the five element tables associated with each indicated Phase gives trie weights for the filter tap summations, indicated in Fig. 12 as coefficients.
  • look-up tables are used to store the coefficients for a finite number of non-integer interpolated values.
  • a common approach is to store the coefficients for 64 discreet phases and select the phase closest to the interpolated value.
  • HDTV High Definition Television
  • the foregoing describes a High Definition Television (HDTV) CRT display operating in a vertical scan mode
  • HDTV High Definition Television
  • the foregoing only illustrates some of the possibilities for practicing the invention.
  • the invention is applicable to a 16:9 screen aspect ratio, but can be applied to systems having a wide variety of aspect ratios like 4:3 or even higher than 16:9, such as 2:1.
  • Many other embodiments are possible within the scope and spirit of the invention. It is, therefore, intended that the foregoing description be regarded as illustrative rather than limiting, and that the scope of the invention is given by the appended claims together with their full range of equivalents.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)

Abstract

L'invention porte sur le tube cathodique d'un système d'affichage et sur son procédé d'utilisation. Ledit tube présente un ensemble de canons à électrons dont les canons en ligne sont alignés verticalement. Le système d'affichage lié au tube cathodique comporte un système de déflexion assurant le balayage des lignes dans le sens vertical. Un système de traitement des signaux vidéo assure la transposition desdits signaux reçus par le système. Le système de déflexion comporte un premier circuit de correction d'image réduisant les distorsions d'image dans au moins une partie de la zone d'affichage. Le système de traitement des signaux vidéo comprend également un deuxième circuit de correction réduisant les distorsions d'image dans au moins la partie de la zone d'affichage prolongeant la partie de la zone d'affichage où le premier circuit de correction réduit les distorsions d'image.
PCT/US2005/011397 2004-09-24 2005-04-06 Tube cathodique de tvhd a balayage vertical et son procede d'utilisation WO2006036200A1 (fr)

Applications Claiming Priority (4)

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US61315504P 2004-09-24 2004-09-24
US60/613,155 2004-09-24
US64087504P 2004-12-31 2004-12-31
US60/640,875 2004-12-31

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PCT/US2005/011394 WO2006036199A1 (fr) 2004-09-24 2005-04-06 Affichage tvhd a balayage vertical

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5170102A (en) * 1989-04-14 1992-12-08 U.S. Philips Corporation Picture display device
US5861710A (en) * 1996-01-08 1999-01-19 Hitachi, Ltd. Color cathode ray tube with reduced moire
US20020047658A1 (en) * 2000-09-13 2002-04-25 Satoru Nakanishi Cathode ray tube and intensity controlling method

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100468422B1 (ko) * 2002-05-14 2005-01-27 엘지.필립스 디스플레이 주식회사 칼라음극선관용 전자총

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5170102A (en) * 1989-04-14 1992-12-08 U.S. Philips Corporation Picture display device
US5861710A (en) * 1996-01-08 1999-01-19 Hitachi, Ltd. Color cathode ray tube with reduced moire
US20020047658A1 (en) * 2000-09-13 2002-04-25 Satoru Nakanishi Cathode ray tube and intensity controlling method

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