US3713001A - High voltage deflection correction in crt displays - Google Patents

High voltage deflection correction in crt displays Download PDF

Info

Publication number
US3713001A
US3713001A US00219465A US3713001DA US3713001A US 3713001 A US3713001 A US 3713001A US 00219465 A US00219465 A US 00219465A US 3713001D A US3713001D A US 3713001DA US 3713001 A US3713001 A US 3713001A
Authority
US
United States
Prior art keywords
anode
voltage
correction
deflection
crt
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00219465A
Other languages
English (en)
Inventor
G Waehner
T Ray
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Raytheon Technologies Corp
Original Assignee
United Aircraft Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by United Aircraft Corp filed Critical United Aircraft Corp
Application granted granted Critical
Publication of US3713001A publication Critical patent/US3713001A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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

  • This invention relates to cathode ray tube deection circuitry, and more particularly to correlation of deflection voltages with anode voltage excursions.
  • a recent addition to the cathode ray tube art is the multiple phosphor, variable penetration type of tube.
  • One such tube comprises a multi-color tube in which phosphors that emit different colors in response to bombardment by electrons are arranged in layers, a lirst layer (closer to the gun of the CRT) excited by lower energy electrons and a second layer (further from the gun of the CRT) being separated therefrom by an energy barrier excited by higher energy electrons.
  • Low anode voltages excite only the iirst phosphor (which may typically be red), while higher anode voltages (causing increasing beam energy) also excite a second phosphor (which may typically be green).
  • the diiierent colors In order to create displays in a plurality of colors, it is necessary to activate the diiierent colors at a sutiiciently rapid rate so as to create the appearance of a steady display to the eye. Typically, generation of all the symbols of one color may be followed by all the symbols of another color, and a third, etc., repetitively in a cyclic fashion. Thus, the anode voltage must be slewed between different color-producing levels at sub-video rates (for instance, the anode voltage may have to change by several kilovolts every tive or ten milliseconds). Slewing of the anode voltage requires that the deflection voltages be altered suitably so as to provide the desired deection Without regard to the desired color.
  • SUMMARY OF INVENTION 'Ihe object of the present invention is to provide automatic correlation between anode voltage and deflection voltage in a CRT display.
  • the deflection voltages applied to a CRT display are correlated to the anode voltage by being amplified with a gain which varies as a function of the square root of the anode voltage.
  • anode correlation may be achieved alone; in accordance with the invention in another form, anode correlation may be achieved on deflection voltages which already have correction for pincushion (or geometry) distortion applied thereto.
  • anode correlation is provided together with CRT geometry distortion correction in an integrated deliection correction and correlation channel which utilizes fewer and simpler components.
  • the present invention provides automatic correlation of CRT deflection voltage with its anode voltage. Since it is automatic, there is no need to accurately control the voltage of the anode power supply. Additionally, the voltage may be readily adjusted, not only in steps to provide different phosphor penetration (such as in multi-phosphor, variable penetration color tubes), but also permits free and easy adjustment of the anode supply so as to vary the hues of colors, or provide similar functions in other displays.
  • the invention eliminates the need for anode voltage monitoring and for switching of compensation circuits at sub-video rates; and it is far simpler, less expensive and more reliable than anode correlation circuits known to the prior art.
  • FIG. 1 is a schematic block diagram of a simple ernbodiment of the present invention.
  • FIG. 2 is a schematic block diagram of an embodiment of the present invention integrated with CRT geometry distortion correction.
  • Each of the multipliers 26, '28 is responsive to a signal on a line 30, which is a function of the square root of the anode voltage on the line 14, in response to a square root circuit 32 which may take any one of several forms. For instance, it may comprise a diode/resistor network of the general type illustrated in a copending application of the same assignee entitled CRT Geometry Correction Network, Ser. No. 155,094, led on June 2l, 1'971 by V. G. Bello.
  • the multiplier 26, 28 may take the form of a reciprocal exponential transconductance multiplier of the type disclosed in our copending application entitled Exponential Transconductance Multiplier and Integrated Video Processor, (UAC Docket No. N-694), filed in December 1971.
  • it may comprise a squaring feedback multiplier or any one of a plethora of other known circuits which can provide the square root function.
  • the multipliers 26, 28 are also responsive to X and Y deection signals applied thereto on related lines 34, 36 from a pair of inputs 38, 40.
  • the deflection voltages applied to the inputs 318 and 40' may either be raw deflection voltages from the video section of apparatus having information to be displayed on the CRT 10, or they may comprise deflection voltages corrected for pincushion (CRT geometry distortion) applied to the inputs 38, 40 by a pincushion correction circuit 42.
  • the pincushion correction circuit 42 as shown in FIG. l, is a minor variation of that disclosed in U.S. Pat. 3,422,306 to S. B. Gray; if desired, it may take that lform, or a more sophisticated and accurate form as disclosed in the aforementioned copending application of Bello.
  • the pincushion correction circuit 42 comprises four multiplier circuit 44-47 and a summing network 48. Because the multiplier 44 is assumed to be an inverting multiplier (or a noninverting multiplier followed by an inverter, if desired), and because both inputs of the summing network 44 are connected to a line 50 which is responsive to raw X deflection voltages applied to a raw input terminal 52 by the video source (not shown), it provides an output on the line 54 which is equal to -KX2. Similarly, the multiplier 45 provides a signal on a line 56 equal to --KY2 in response to raw Y deflection voltages applied over a line 58 from a raw Y input terminal 60.
  • the summing network 48 has an input applied thereto from a terminal 62 which is a constant voltage suitably adjusted to be equivalent to unity in the given implementation of the present invention. This is achieved by suitable choice of the scale factors, or gains, in the circuit, relative to the voltage input at the terminal 62 so that deflections giving the sum (xH-y2) equal to unity will result in no output from the summing network 48, as is well known in the art.
  • the output of the summing network 48 on a line 70 comprises a signal equivalent to This signal is applied by a line 70 to the multipliers 46, 47 together with the raw X and raw Y deflection voltages, respectively, so as to provide CRT distortion corrected X and Y deflection voltages on related signal lines 72, 74 as follows:
  • Equations 4 and 5 will be recognized by those skilled in the art as expressions for deflection voltages which have been approximately corrected for CRT distortion. By making K2 a nonlinear variable, the more accurate correction of the Bello application may be achieved, as described therein. By substituting Equations 4 and 5 into Equations l and 2 it can be seen that the actual deection voltages achieved in the full circuitry of FIG. l are It should be understood that the geometry distortion correction circuitry 42 forms no part of the present invention, but is described herein as an aid in understanding a second embodiment of the invention in which anode correlation and geometry distortion correction are integrated, as is illustrated in FIG. 2.
  • the summing network 48a does not have a constant input thereto, so that its output on a line 76 comprises simply This is applied to a multiplier 78 (which in a sense combines the functions of the multipliers 46, 47) to which the output of the square root circuit 32 is also applied so as to generate a signal on a line 80 which is equivalent to The signal on the line 80 is applied to a summing network 82 which is also responsive to the anode voltage on the line 14 to provide a signal on a line 84 which is Then, the multipliers 26, 28 respond to the signal on the line 84 and to the respective signals on lines 50 and 58 so as to provide It can be seen that IEquations l1 and l2 are the same as Equations 6 and 7.
  • the circuit of FIG. 2 provides, in an integrated fashion, the combined distortion correction and anode voltage correlation as provided independently by the distortion correction
  • the multipliers 44, 45 must be four-quadrant multipliers since both inputs may be either positive or negative.
  • the multipliers 26, 28 and 46, 47 need only be two-quadrant multipliers since the inputs thereto on lines 30 and 70, respectively, are always positive and only the other inputs could be either positive or negative.
  • the multipliers 78 in FIG. 2 need only be a single quadrant multiplier since both inputs are always positive. As is known, fewer quadrants usually can be achieved in less expensive circuitry; thus, there is an additional advantage to the circuit of FIG. 2, in that it not only eliminates one multiplier compared to the total circuitry of FIG. l, but allows use of a simpler one as well.
  • the present invention may be practiced Without pincushion correction by using simply the apparatus 10-40 in FIG. 1, and not utilizing the pincushion (or geometry distortion) correction circuit 42 in FIG. 1, nor related apparatus in FIG. 2.
  • This may be advantageous where space, cost or Weight are critical factors since the dependence of deflection on high voltage is a forty to fifty percent effect, Whereas the deflection correction is more like a ten percent effect.
  • the multipliers used only for pincushion correction need not be high quality, though it is preferable that the multipliers used in anode correlation be of relatively high quality.
  • a cathode ray tube display system comprising:
  • a cathode ray tube having a high voltage anode having a high voltage anode
  • a high voltage supply connected to said anode and providing an anode voltage thereto;
  • the deflection voltage modification apparatus comprising:
  • a cathode ray tube having a high voltage anode having a high voltage anode
  • a high voltage supply providing an anode voltage to the anode of said cathode ray tube
  • sun means receiving ⁇ raw x and y deflection voltage signals and providing a negative scalar of the sum of the squares thereof;

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Details Of Television Scanning (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
US00219465A 1972-01-20 1972-01-20 High voltage deflection correction in crt displays Expired - Lifetime US3713001A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US21946572A 1972-01-20 1972-01-20

Publications (1)

Publication Number Publication Date
US3713001A true US3713001A (en) 1973-01-23

Family

ID=22819371

Family Applications (1)

Application Number Title Priority Date Filing Date
US00219465A Expired - Lifetime US3713001A (en) 1972-01-20 1972-01-20 High voltage deflection correction in crt displays

Country Status (5)

Country Link
US (1) US3713001A (sl)
JP (1) JPS5721903B2 (sl)
CA (1) CA979535A (sl)
FR (1) FR2168303B1 (sl)
GB (1) GB1391815A (sl)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0070677A2 (en) * 1981-07-14 1983-01-26 Dai Nippon Printing Co., Ltd. Video printing apparatus
EP0089505A1 (en) * 1982-03-19 1983-09-28 International Business Machines Corporation CRT deflection distortion correcting circuit
EP0110282A1 (en) * 1982-11-23 1984-06-13 Tektronix, Inc. Image distortion correction method and apparatus

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5098223A (sl) * 1973-12-26 1975-08-05
FR2483667A1 (fr) * 1980-06-03 1981-12-04 Thomson Csf Dispositif d'echantillonnage et maintien a capacite mos
GB2307382A (en) * 1995-11-13 1997-05-21 Thomson Multimedia Sa Deflection circuit compensates for EHT variations

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0070677A2 (en) * 1981-07-14 1983-01-26 Dai Nippon Printing Co., Ltd. Video printing apparatus
EP0070677A3 (en) * 1981-07-14 1986-12-30 Dai Nippon Printing Co., Ltd. Video printing apparatus
EP0089505A1 (en) * 1982-03-19 1983-09-28 International Business Machines Corporation CRT deflection distortion correcting circuit
US4501996A (en) * 1982-03-19 1985-02-26 International Business Machines Corporation Deflection distortion correcting circuit
EP0110282A1 (en) * 1982-11-23 1984-06-13 Tektronix, Inc. Image distortion correction method and apparatus

Also Published As

Publication number Publication date
CA979535A (en) 1975-12-09
JPS4883870A (sl) 1973-11-08
GB1391815A (en) 1975-04-23
JPS5721903B2 (sl) 1982-05-10
FR2168303A1 (sl) 1973-08-31
FR2168303B1 (sl) 1976-06-04

Similar Documents

Publication Publication Date Title
US4631576A (en) Nonuniformity correction system for color CRT display
GB602053A (en) Improvements relating to colour television reception
NO151913B (no) Styreanordning for katodestraaleroer
US3196205A (en) Color television camera system
US3713001A (en) High voltage deflection correction in crt displays
GB708016A (en) Improvements in or relating to apparatus for translating electric signals into legible characters
US3891889A (en) Color convergence apparatus for a color television tube
US2189898A (en) System of communication
GB1510700A (en) Convergence circuit for a multi-gun cathode ray tube
US3930120A (en) Multi-beam cathode ray tube having equalized line brightness
US2962545A (en) Automatic flying spot scanner light intensity control
USRE28631E (en) High voltage deflection correction in CRT displays
US3457365A (en) High resolution television projection system
GB716889A (en) Improvements in or relating to cathode-ray tubes for use in television and to line-scanning circuits therefor
GB663171A (en) Television system
US3541233A (en) Color conversion system for x-rays
US3226475A (en) Function generators especially for colour television receivers
US3098170A (en) Power supply circuit for television receivers
US3716749A (en) Display system to generate symbols formed of conic sections
US2924742A (en) Cathode ray character display system
US3842310A (en) Multiplying integrator circuit
US3714505A (en) Dynamic focus correction apparatus for a rectilinearly raster scanned electron beam
US2643289A (en) Television system
GB836015A (en) Improvements relating to apparatus for reproducing images in colour
GB966711A (en) Improvements in and relating to amplifier circuits