Circuits Control Grid-cathode Circuit Of Tube Patents (Class 315/381)
  • Patent number: 8026674
    Abstract: An electron source has an electron emitter with an electron emission cathode, a high voltage unit provided for power supply of the electron emission cathode, and a low voltage unit provided to control the high voltage unit. Data are transmitted non-electrically (in particular optically) between the high voltage unit and the low voltage unit.
    Type: Grant
    Filed: September 5, 2008
    Date of Patent: September 27, 2011
    Assignee: Siemens Aktiengesellschaft
    Inventors: Jan Berk, Josef Deuringer
  • Patent number: 7423390
    Abstract: An electron beam generator for multiple columns includes: a plurality of cathodes, to which a single acceleration voltage supply applies a negative acceleration voltage, and which thus generates thermoelectrons; a grid for each of the plurality of cathodes, the grid converging the thermoelectrons emitted to form a beam of electrons; a grid voltage supply for giving the grid a potential which is negative relative to a potential of the cathode; and a control circuit for each cathode, for controlling the potential of the grid. The control circuit includes a current direction restricting element connected between a positive electrode of the grid voltage supply and the cathode, and a grid current supplied from the grid voltage supply is caused to flow to the cathode through the current direction restricting element.
    Type: Grant
    Filed: February 8, 2007
    Date of Patent: September 9, 2008
    Assignee: Advantest Corp.
    Inventor: Takamasa Sato
  • Patent number: 7030908
    Abstract: Disclosed are a method and an apparatus for preventing appearance of a zigzag flush of light in a cathode-ray tube at the time of turning it off. A train of power-off control pulses are produced in synchronization with the vertical sweeping signal; a spot-killer control signal starts in synchronization with a selected power-off pulse to make the whole screen of the cathode-ray tube bright; and the power supply turns off in synchronization with another selected power-off control pulse, so that the power-off is caused at the termination of the vertical sweeping. Thus, the remaining static electricity is discharged at the lowermost of the screen of the cathode-ray tube. To assure that the residual static electricity is discharged completely, the length of time “t1” (continuing for a selected integer as long as the pulse-to-pulse duration) is determined to meet the size of the cathode-ray tube.
    Type: Grant
    Filed: March 19, 2003
    Date of Patent: April 18, 2006
    Assignee: Orion Electric Co., Ltd.
    Inventor: Kazuyuki Iji
  • Patent number: 6937288
    Abstract: In a beam current limiting circuit for a video projector, an average current is limited under closed loop control containing an anode current detection circuit 5. On the other hand, a cathode current detection circuit 107 comprises a first resistor and a second resistor in series to a cathode current circuit and detects a cutoff current at the voltage across the first resistor and an average current at the voltage across the second resistor. An offset addition circuit 11 is provided for correcting the detection value of the average current based on the maximum value of detected cathode current, and beam current is limited. Further, means 15 for detecting time change of anode current is provided and if the current value does not change for a long time, the beam current is limited to a smaller value.
    Type: Grant
    Filed: April 19, 2001
    Date of Patent: August 30, 2005
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Taketoshi Hibi
  • Patent number: 6903519
    Abstract: Apparatus and method are provided for using a multi-element field emission cathode in a color cathode ray tube. The field emission cathode may have from four to ten field emission arrays linearly arranged. The arrays are preferably formed from carbon-based material. An electron gun assembly focuses electron beams from each array on to a phosphor stripe or dot on the screen of the cathode ray tube. Deflection apparatus moves the beam from each field emission array according to clock signals. Clock signals also turn on or turn off voltage to contacts controlling electron current from the array. Values of voltage applied, determined by a video signal, determine the intensity of electron current from each array, which controls the intensity of the light emitted by each color stripe or dot of phosphor on the phosphor screen.
    Type: Grant
    Filed: July 28, 2003
    Date of Patent: June 7, 2005
    Assignee: Trepton Research Group, Inc.
    Inventors: Byron G. Zollars, John J. Lorr, Kent R. Kalar
  • Patent number: 6856104
    Abstract: The high voltage supply for a picture tube comprises a high voltage transformer, which generates the anode voltage of the picture tube, and a high voltage module with a switched mode power supply for providing a grid voltage, which is higher than the anode voltage. The output of the high voltage transformer is coupled to the transformer of the switched mode power supply, for adding the output voltage of the switched mode power supply to the high voltage of the high voltage transformer. Preferably, the transformer of the switched mode power supply provides the high voltage isolation, and at least the high voltage part of the module including the transformer is potted with a resin. The high voltage module provides advantageously also an output for a connection to the anode of the picture tube, so that the module can be used with present high voltage transformers, without requiring any modification.
    Type: Grant
    Filed: January 21, 2002
    Date of Patent: February 15, 2005
    Assignee: Thomson Licensing S.A.
    Inventors: Daniel Lopez, Jean-Paul Louvel, Martin Läufer
  • Patent number: 6800992
    Abstract: A focusing electrode and a final accelerating electrode accommodate, respectively, a first and a second field forming electrode in positions set back from a first and a second aperture of their end faces opposed to each other. The first and the second field forming electrode have three electron beam passage apertures disposed in an in-line arrangement. When the in-line direction is an X-axis direction, a direction perpendicular to the in-line direction is a Y-axis direction and the center of a central electron beam passage aperture formed in the first field forming electrode is X=0 and Y=0, the central electron beam passage aperture has a shape that passes through the intersection points of the X-axis and the Y-axis with a curve represented by the equation (X/R1)2+(Y/R2)2=1 (where R1 and R2 are constants) and that has an area smaller than the area encircled by the curve.
    Type: Grant
    Filed: May 1, 2003
    Date of Patent: October 5, 2004
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Yasufumi Wada, Hiroji Morimoto
  • Patent number: 6727658
    Abstract: An electron beam generating apparatus for generating a plurality of electron beams, which includes: a plurality of cathodes for generating thermoelectrons; a cathode power supply unit for applying negative voltage to the cathodes so as to emit the thermoelectrons from the cathodes; a plurality of grids, which correspond to the plurality of cathodes respectively, for focusing the thermoelectrons emitted from each of the plurality of cathodes, and shaping the plurality of electron beams; and an insulator on which the plurality of cathodes and the plurality of grids are attached.
    Type: Grant
    Filed: March 7, 2003
    Date of Patent: April 27, 2004
    Assignee: Advantest Corporation
    Inventors: Yoshihisa Ooae, Yoichi Shimizu, Takamasa Satoh, Takeshi Haraguchi
  • Publication number: 20040075403
    Abstract: The high voltage supply for a picture tube (T) comprises a high voltage transformer (DST), which generates the anode voltage of the picture tube, and a high voltage module (M) with a switched mode power supply for providing a grid voltage, which is higher than the anode voltage. The output of the high voltage transformer (DST) is coupled to the transformer (TR) of the switched mode power supply, for adding the output voltage of the switched mode power supply to the high voltage of the high voltage transformer. Preferably, the transformer (TR) of the switched mode power supply provides the high voltage isolation, and at least the high voltage part of the module (M) including the transformer is potted with a resin. The high voltage module provides advantageously also an output (3) for a connection to the anode of the picture tube, so that the module can be used with present high voltage transformers, without requiring any modification.
    Type: Application
    Filed: July 30, 2003
    Publication date: April 22, 2004
    Inventors: Daniel Lopez, Jean-Paul Louvel, Martin Lufer
  • Patent number: 6686710
    Abstract: A circuit for regulating a signal, such as a cathode current. The circuit has an input stage for inputting a signal and for producing a sense signal based thereon. The circuit may input timing signals and have a first stage for comparing a first reference signal with the sense signal when a first timing signal indicates and for outputting a first correction signal based on the comparison. The circuit may have a second stage for comparing a second reference signal with the sense signal when a second timing signal indicates and for outputting a second correction signal based on the comparison. The circuit may further have elements for measuring a leakage signal in the input signal during a third time interval. In this embodiment, the first and second stages are further for subtracting the leakage signal from the sense signal prior to the comparisons.
    Type: Grant
    Filed: December 18, 2002
    Date of Patent: February 3, 2004
    Assignee: National Semiconductor Corporation
    Inventors: Charles Guan, Andrew Morrish
  • Patent number: 6636265
    Abstract: An inventive method for preventing focus flutter display in a TV receiver or monitor includes the steps of amplifying a received signal for driving cathode elements of a cathode ray tube, and delaying initial full amplification of the signal during the amplifying step for a duration sufficient to prevent focus flutter display on the tube. A corresponding inventive kine driver circuit that prevents display of focus flutter includes an amplifier for amplifying and coupling received video signals to cathode elements of a picture tube, and a control circuit for delaying full amplification of the video signals to be fed to the cathode elements for a duration sufficient to prevent focus flutter display on the tube.
    Type: Grant
    Filed: June 7, 2000
    Date of Patent: October 21, 2003
    Assignee: Thomson Licensing S.A.
    Inventor: Isaac Michael Bell
  • Patent number: 6563276
    Abstract: A CRT display apparatus capable of displaying images in high contrast and high brightness without causing noises and halftone-reproduction degradation within dark areas is disclosed. The apparatus includes a circuit for generating an R-control signal, a G-control signal and a B-control signal by removing, from each of the R-, G- and B-video signals, portions which are below a predetermined level in amplitude, an amplification circuit for inverting and amplifying the R-, G- and B-control signals, and a selection circuit for selecting, for each of the three G1 electrodes, either a corresponding one of the R-, G- and B-control signals inverted and amplified by the amplification circuit or a potential of a predetermined value in accordance with an instruction from an outside, and applying each of the three G1 electrodes with a selected one of the corresponding one of the R-, G- and B-control signals and the potential.
    Type: Grant
    Filed: November 21, 2001
    Date of Patent: May 13, 2003
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Akinori Heishi, Hironobu Yasui, Tetsuya Shimizu
  • Patent number: 6541927
    Abstract: The format of a color video signal that has been inputted into a CPU from a video amplifying circuit is identified, and based on a given parameter variable according to this identified format, a second grid electrode voltage and the cathode bias voltages of cathodes for the three primary colors are determined, thereby driving a cathode ray tube with an optimal driving condition adequate for the video signal format. This parameter variable may be adjusted through a manual operation, allowing a user to set any desired driving condition for the cathode ray tube.
    Type: Grant
    Filed: April 11, 2001
    Date of Patent: April 1, 2003
    Assignee: Sony Corporation
    Inventor: Hiroshi Yamashita
  • Patent number: 6538370
    Abstract: A cathode-ray tube electron gun can alleviate unwanted radiation caused when cathodes and a first electron gun constitute an antenna by increasing the number of conduction leads of a first electrode of a cathode-ray tube electron gun from one to a plurality of conduction leads.
    Type: Grant
    Filed: July 27, 1999
    Date of Patent: March 25, 2003
    Assignee: Sony Corporation
    Inventors: Yasunobu Amano, Norifumi Kikuchi, Takashi Shirai, Motomu Tadama, Kazuo Sugimoto, Mitsunori Endou
  • Patent number: 6509680
    Abstract: The stray emission in an electron gun comprising a main lens system with one or more intermediate electrodes (42, 43, 44) between the focus electrode (41) and the anode electrode (45) is reduced if at least one of the apertures of the main lens system following the focus electrode has apertures which are smaller than those of the focus electrode. The optimal stray emission situation can be found by designing all the apertures of the main lens system. In order to manufacture an electron gun according to the invention, it is advantageous to have an outside reference system for gun mounting, because it will no longer be possible to center the electrodes on pins through the apertures.
    Type: Grant
    Filed: December 16, 1999
    Date of Patent: January 21, 2003
    Assignee: Koninklijke Philips Electronics N.V.
    Inventor: Wilhelmus A. M. Aarnink
  • Publication number: 20030001526
    Abstract: A CRT display apparatus capable of displaying images in high contrast and high brightness without causing noises and halftone-reproduction degradation within dark areas is disclosed. The apparatus includes a circuit for generating an R-control signal, a G-control signal and a B-control signal by removing, from each of the R-, G- and B-video signals, portions which are below a predetermined level in amplitude, an amplification circuit for inverting and amplifying the R-, G- and B-control signals, and a selection circuit for selecting, for each of the three G1 electrodes, either a corresponding one of the R-, G- and B-control signals inverted and amplified by the amplification circuit or a potential of a predetermined value in accordance with an instruction from an outside, and applying each of the three G1 electrodes with a selected one of the corresponding one of the R-, G- and B-control signals and the potential.
    Type: Application
    Filed: November 21, 2001
    Publication date: January 2, 2003
    Inventors: Akinori Heishi, Hironobu Yasui, Tetsuya Shimizu
  • Patent number: 6479952
    Abstract: A display apparatus includes a CRT, the CRT including an electron gun having a cathode, a G1 electrode, a G2 electrode, and a G3 electrode disposed in that order to draw electrons from the cathode. The electron gun further has a modulating Gm electrode disposed between the G2 and G3 electrodes. The display apparatus is provided with a controller for controlling a value of a voltage applied to the Gm electrode to adjust brightness of a picture on a screen of the CRT.
    Type: Grant
    Filed: March 28, 2001
    Date of Patent: November 12, 2002
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Hironobu Yasui, Akinori Heishi
  • Patent number: 6462487
    Abstract: A method for operating a cathode-ray tube electron gun, suitable for multimode operation, for example, in order to display television images and multimedia images of the SVGA, XGA type, in which the zone for forming the electron beam generated by the cathode has at least two control electrodes. The two control electrodes are connected to voltage sources in such a way that the potential difference between the two control electrodes increases when the beam current decreases.
    Type: Grant
    Filed: August 21, 2000
    Date of Patent: October 8, 2002
    Assignee: Thomson Tubes & Displays, S.A.
    Inventors: Michel Lefort, Jean-Pierre Garnier
  • Patent number: 6452320
    Abstract: A main lens of an electron gun of a cathode ray tube is provided. The main lens for receives a plurality of parallel and co-planar electron beams emitted by the electron gun. The lens focuses each electron beam along a respective one of a plurality of focal axes incident to a display surface. A first grid electrode is positioned substantially orthogonally with respect to the plurality of electron beams, the grid electrode includes a plurality of apertures.
    Type: Grant
    Filed: August 9, 2000
    Date of Patent: September 17, 2002
    Assignees: Sarnoff Corporation, Orion Electric Company, LTD
    Inventor: David Arthur New
  • Patent number: 6433827
    Abstract: A method for calibrating a screen grid voltage of the color picture tube in a color television set having automatic cut-off regulation. The method comprises the steps of, changing a normal operating potential at control electrodes of the color picture tube; adjusting the screen grid voltage about a value until values causing a fly-back line to be alternately visible and extinguished converge on the value; and, resetting the normal operating potential at the control electrodes of the color picture tube.
    Type: Grant
    Filed: April 5, 2000
    Date of Patent: August 13, 2002
    Assignee: Thomson Licensing SA
    Inventor: Gerold Lübcke
  • Patent number: 6388403
    Abstract: A process for color adjustment of a color monitor including a cathode-ray tube and a brightness adjustment module includes providing a nominal brightness signal downstream of a white level adjustment module for adjusting a white level and upstream of a black level adjustment module for adjusting a black level. The process also includes setting a voltage required to obtain a black color image, setting a voltage required to obtain a white color image, providing the nominal brightness signal upstream of the white level adjustment module, and setting the voltage required to obtain the black color image.
    Type: Grant
    Filed: January 25, 2001
    Date of Patent: May 14, 2002
    Assignee: STMicroelectronics S.A.
    Inventor: Jean-Pierre Blanc
  • Patent number: 6353281
    Abstract: A color cathode ray tube including a panel section having a phosphor layer formed on an internal surface thereof, a neck portion having an electron gun assembly for emission of three electron beams therein, and a funnel section connecting the panel section and the neck portion. The electron gun assembly includes three cathodes and a plurality of grid electrodes disposed along a tube axis. The grid electrodes includes at least one plate-shaped electrode which has a fixed support structure. The plate-shaped electrode has three bulged portions along an electron beam passage, a first electron beam passage hole being formed in a respective bulged portion and a second electron beam passage being hole formed in a top face portion of a respective bulge portion. A diameter of the first electron beam passage hole is greater than a diameter of the second electron beam passage hole.
    Type: Grant
    Filed: April 13, 2001
    Date of Patent: March 5, 2002
    Assignees: Hitachi, Ltd., Hitachi Device Engineering, Co., Ltd., Hitachi Electronic Devices Co., Ltd.
    Inventors: Mitsuhiro Sugiyama, Tsutomu Tojyo, Masahiro Ito, Masayoshi Misono, Hiroyuki Tamura
  • Patent number: 6288503
    Abstract: At the onset of ageing or in the further course of their service life, color picture tubes relatively frequently exhibit a rise in the field strength between the cathode (K) and the Wehnelt electrode (G1) of the respective beam system on account of a blooming effect of the cathodes (K) which is known per se and reduces the spacing between cathode (K) and Wehnelt electrode (G1). The cut-off regulation reacts to an effect of this type in a manner such that the reverse voltage acting between cathode (K) and Wehnelt electrode (G1) is correspondingly reduced in order to be able to drive the same reference cathode current. However, the reaction of the cut-off regulation must be taken into account for the circuit design since this would otherwise result in an unacceptable reduction in the modulation range, which would, in turn, have an adverse effect on the maximum contrast setting.
    Type: Grant
    Filed: June 28, 1999
    Date of Patent: September 11, 2001
    Assignee: Deutsche Thomas-Brandt GmbH
    Inventor: Helmut Sowig
  • Patent number: 6285143
    Abstract: A grid kick circuit for applying beam cut-off bias to the grid of a kinescope to provide spot burn protection. The circuit includes a first switching circuit having an output coupled to a first electrode of a grid kick capacitor and a second switching circuit having an output coupled to a second electrode of the capacitor and the grid. When beam blanking is not desired, charging current is supplied to the capacitor through a first current path from a first voltage source while the second switching circuit regulates the voltage at a second electrode of the capacitor and the grid. Current for the second switching circuit is provided by a second current path which is coupled to the first voltage source and is independent of the first path.
    Type: Grant
    Filed: December 22, 1998
    Date of Patent: September 4, 2001
    Assignee: Thomson Licensing S.A.
    Inventor: Dal Frank Griepentrog
  • Publication number: 20010009355
    Abstract: A color cathode ray tube has G1-G5 electrodes and an anode. The G5 electrode is divided into sub-electrodes supplied alternately with a first fixed focus voltage and a second focus voltage which is a second fixed voltage superposed with a dynamic voltage, at least one electrostatic quadrupole lens is formed between adjacent ones of the sub-electrodes, and two of the sub-electrodes are supplied with the second focus voltage. The following inequalities are satisfied: 0.0625×L (mm)≦B−20A/(3&phgr;)≦22.0 mm, L (mm)≦352 mm, where A is an axial length of the G4 electrode, &phgr; (mm) is an average diameter of a center aperture in the G4 electrode, B (mm) is a length from a cathode side end to a phosphor screen side end of said G5 electrode to the phosphor screen.
    Type: Application
    Filed: March 15, 2001
    Publication date: July 26, 2001
    Inventors: Yasuharu Yatsu, Tomoki Nakamura, Shoji Shirai
  • Patent number: 6232711
    Abstract: A color cathode ray tube includes a panel section having an internal surface with a phosphor layer formed thereon and a neck portion accommodating therein an electron gun assembly for emission of a plurality of electron beams plus a funnel section connecting the panel section and the neck portion together, wherein the electron gun assembly is designed to have a plate-shaped electrode with a plurality of electron beam passage holes corresponding in the number to the electron beams. The plate electrode has cylindrical bulged portions projecting in a way corresponding to the plurality of electron beams, each of which portion has its top face in which an electron beam opening or hole is formed. The present invention provides a color cathode ray tube comprising a readily manufacturable high-resolution electron gun assembly.
    Type: Grant
    Filed: December 14, 1999
    Date of Patent: May 15, 2001
    Assignees: Hitachi, Ltd., Hitachi Device Engineering Co., Ltd., Hitachi Electronic Devices Co., Ltd.
    Inventors: Mitsuhiro Sugiyama, Tsutomu Tojyo, Masahiro Ito, Masayoshi Misono, Hiroyuki Tamura
  • Patent number: 6226037
    Abstract: An AKB interface apparatus in a display system (10), includes a video signal processing IC (12) having outputs coupled via respective kinescope driver ICs (18,20,22) to respective kinescope cathodes (K1,K2,K3) for display of a color image, the signal processing IC having an input 27 for receiving an AKB input signal, the driver ICs having respective outputs (28,30,32) providing respective cathode current indicating signals (RP,GP,BP) An interface circuit (100) couples the cathode current indicating signals to the AKB input of the signal processing IC. The interface circuit comprises a load circuit (110) for generating a load voltage (Vo) in response to at least one of the cathode current indicating signals. A leakage correction circuit (130), responsive to said load voltage (Vo), feeds back a leakage correction current (Io) to the load circuit.
    Type: Grant
    Filed: December 30, 1998
    Date of Patent: May 1, 2001
    Assignee: Thomson Licensing S.A.
    Inventor: Dal Frank Griepentrog
  • Patent number: 6211908
    Abstract: Supplementary grid blanking and spot burn protection are provided in a receiver/monitor (10) by a grid bias control circuit (50) including a blanking signal generator (60) that produces a blanking output signal (S1) devoid of any picture representative component whenever a vertical blanking signal (VB) or a horizontal blanking signal (HB) is present. A capacitor (C1) strips DC from the blanking signal and the resultant signal (S2) is applied to a modulation input (84) of a grid bias generator to produce an output grid bias reference voltage (Vr) modulated by the AC component of the blanking signal. The reference voltage (Vr) is coupled via a spot burn protection circuit (100) and a grid coupling circuit (120) to the control grids of three projection kinescopes (16, 18, 20).
    Type: Grant
    Filed: May 27, 1999
    Date of Patent: April 3, 2001
    Assignee: Thomson multimedia Licensing S.A.
    Inventor: Dal Frank Griepentrog
  • Patent number: 6046552
    Abstract: A spot is prevented from occurring on the center portion of a cathode ray tube when electric power is turned off by using a voltage charged in a capacitor which are used for outputting a vertical blanking signal in a vertical blanking signal generating circuit of an image display device for displaying an image in use of the cathode ray tube. The present invention is provided with a discharge cut-off element between a negative electric power source and the capacitor for outputting a vertical blanking signal and a discharging element for discharging a charged voltage of the capacitor to the ground. The present invention prevents a charged voltage ofthe capacitor from being discharged until thermoelectrons are not emitted from the cathode so as to supply a negative charged voltage to the first grid of the cathode ray tube continuously, so that a spot is prevented from occurring.
    Type: Grant
    Filed: December 30, 1997
    Date of Patent: April 4, 2000
    Assignee: SamSung Electronics Co., Ltd.
    Inventor: Kyung Choon Yoon
  • Patent number: 6020693
    Abstract: A method is provided for reducing a residual spot on a cathode ray tube when a power supply is turned off. The method is executed by applying a holding voltage being no less than the value of the voltage enabling to enhance the back raster luminance and a cut-off voltage, or a voltage of a lower value, to a second grid electrode while the anode voltage is lowered to a predetermined voltage value when the main power supply is turned off.
    Type: Grant
    Filed: December 8, 1997
    Date of Patent: February 1, 2000
    Assignee: Sony Corporation
    Inventor: Minoru Makida
  • Patent number: 5969762
    Abstract: A kinescope video driver includes a series connection of a main cascode transistor coupled to a cathode of a cathode ray tube and a video signal amplifying transistor. A second cascode transistor is coupled between the main cascode transistor and the video signal amplifying transistor. The second transistor is coupled to the video signal amplifying transistor through a short wire conductor and to the main cascode transistor through a long wire conductor.
    Type: Grant
    Filed: February 26, 1997
    Date of Patent: October 19, 1999
    Assignee: Thomson Consumer Electronics, Inc.
    Inventor: John Barrett George
  • Patent number: 5949400
    Abstract: An apparatus for correcting a chromaticity diagram by a variable brightness includes: a first grid voltage controller for controlling a first grid voltage to be a voltage of a predetermined level; a first grid voltage detector for detecting the first grid voltage output by the first grid voltage controller; a phase inverter for inverting a phase of a voltage signal detected by the first grid voltage detector; an analog-to-digital converter for converting the inputted voltage signal, which has been phase-inverted by the phase inverter, into a digital signal; a microprocessor for receiving the digital data of the first grid voltage output from the analog-to-digital converter to produce and output error data; a digital-to-analog converter for converting the error data supplied from the microprocessor into an analog signal, and a cut-off controller for receiving the analog signal output from the digital-to-analog converter and correcting a color-difference signal.
    Type: Grant
    Filed: December 20, 1996
    Date of Patent: September 7, 1999
    Assignee: SamSung Electronics Co., Ltd.
    Inventor: Eun-Sup Kim
  • Patent number: 5903111
    Abstract: A CRT protective circuit capable of eliminating spots during a mode conversion operation includes a microprocessor for generating a mute signal according to externally-provided horizontal and vertical sync signals, and a high voltage generating section for generating a high voltage according to an operation of a flyback transformer. A first switching section is switched according to the mute signal for supplying the high voltage of the high voltage generating section to a grid terminal, and a high voltage dropping section divides the output voltage of the high voltage generating section according to the switching status of the first switching section and supplies the dividing voltage to the grid terminal to control brightness of the spots.
    Type: Grant
    Filed: May 21, 1997
    Date of Patent: May 11, 1999
    Assignee: Daewoo Electronics Co., Ltd.
    Inventor: Hyun-Gook Shin
  • Patent number: 5894327
    Abstract: Video signals to be displayed are applied via a video driver amplifier to the cathode electrode of a kinescope. A beam current sensor, also coupled to the cathode electrode, provides a beam current indicating signal. An AKB regulator, responsive to the beam current indicating signal, supplies a black level correction signal to the driver amplifier for regulating the black level of images displayed by the kinescope. A screen grid supply system is provided for controlling the G-2 (screen grid) voltage of the kinescope as a predetermined function of the black level correction signal thereby forming with the AKB regulator a dual feedback loop for providing black level regulation by both the driver amplifier and the screen grid thereby maximizing or extending the overall black level control range.
    Type: Grant
    Filed: August 6, 1997
    Date of Patent: April 13, 1999
    Assignee: Thomson Consumer Electronics, Inc.
    Inventor: Dal Frank Griepentrog
  • Patent number: 5856730
    Abstract: A display system includes a kinescope. A horizontal scan detector is coupled to a source of a horizontal scan current signal and detects a loss of horizontal scanning. In addition, a vertical scan detector is coupled to a source of a vertical scan current signal including a feedback path and detects a loss of vertical scanning. A vertical feedback detector is also coupled to the vertical scan current signal source, and detects a failure of the feedback path in the vertical scan current signal source. A controllable kinescope driver circuit, coupled to the kinescope, the horizontal scan detector, the vertical scan detector and the vertical feedback detector, blanks the kinescope if the horizontal scan detector detects a loss of horizontal scanning, the vertical scan detector detects a loss of vertical scanning or the vertical feedback detector detects a failure of the feedback path.
    Type: Grant
    Filed: February 26, 1997
    Date of Patent: January 5, 1999
    Assignee: Thomson Consumer Electronics, Inc.
    Inventor: John Barrett George
  • Patent number: 5828190
    Abstract: The frequency roll-off experienced by video signals applied to the three cathodes of a color cathode ray tube, due to the capacitance between the cathodes and the common control grid, is compensated with a single inductor connected in series with the common control grid.
    Type: Grant
    Filed: May 15, 1997
    Date of Patent: October 27, 1998
    Assignee: Zenith Electronics Corporation
    Inventor: William J. Mark
  • Patent number: 5808425
    Abstract: The invention is directed to a method for controlling the emission current of an electron source and to a correspondingly controlled electron source. For this purpose, a parallel circuit comprising resistors 6 and field-effect transistors 7 is connected in the high-voltage circuit between the cathode 1 and the control electrode 2. The supply voltage for the field-effect transistors 7 is generated by voltage dividing the voltage across the resistors 6. The measurement of the emission current takes place at low-voltage potential and a control signal obtained from the measuring signal is optically transmitted via a light-conducting fiber or a light waveguide to the control circuit in the high-voltage part. The emission current control at high-voltage potential is provided without additional voltage supplies. Additional insulating transformers are therefore not required.
    Type: Grant
    Filed: June 19, 1996
    Date of Patent: September 15, 1998
    Assignee: Carl-Zeiss-Stiftung
    Inventor: Rainer Harle
  • Patent number: 5719477
    Abstract: The electron gun with a field emission type cathode includes a substrate, a plurality of groups of cathodes disposed on the substrate, each group having a conically shaped electron-emitter, and gate electrodes each associated with each group of the plurality of groups of cathodes for causing the conically shaped electron-emitter to emit electrons by field emission. A control voltage can be applied independently to each group of the plurality of groups of cathodes, and also to the gate electrodes.
    Type: Grant
    Filed: July 12, 1996
    Date of Patent: February 17, 1998
    Assignee: NEC Corporation
    Inventor: Yoshinori Tomihari
  • Patent number: 5719475
    Abstract: An electron gun having an improved circuitry for driving the electron gun, which includes a cathode ray tube accommodating at least a cathode, a control electrode, a first acceleration electrode, a convergence electrode comprising first and second grids sandwiching at least a quadrupole lens and a second acceleration electrode. The circuitry is provided with a voltage divider having first and second ends which are electrically connected between the control electrode and the first grid respectively. The voltage divider being electrically connected to at least a dc power supply to apply a bias between the first and second ends of the voltage divider so that the first and second ends of the voltage divider have first and second voltage levels which are different by the bias from each other. The voltage divider has a voltage dividing point between the first and second ends.
    Type: Grant
    Filed: April 29, 1996
    Date of Patent: February 17, 1998
    Assignee: NEC Corporation
    Inventor: Akira Shishido
  • Patent number: 5714842
    Abstract: The present invention, generally speaking, provides for automatic cutoff control in a DC coupled CRT video drive using a low DC supply voltage and circuitry that is lower in power consumption than conventional circuitry for the comparable video performance. A simple, easy to implement solution is achieved with an extremely low component count. Cutoff control response is fast, allowing discontinuous operation of auto cutoff control. In one embodiment of the invention, a cutoff control signal is applied to individual CRT G1 terminals. Fast response cutoff control drive is realized using an IC current source and a single transistor current-to-voltage (CTV) converter. Supply voltage variations on the video driver are clamped via a clamping device to the negative supply voltage of the G1 CTV converter.
    Type: Grant
    Filed: July 21, 1995
    Date of Patent: February 3, 1998
    Assignee: Apple Computer, Inc.
    Inventors: Peter Krause, Aik Keong Ong
  • Patent number: 5682083
    Abstract: A spot removing circuit for a display device is disclosed. The spot removing circuit comprises a rectifying and smoothing portion for rectifying and smoothing the voltage outputted from a flyback transformer, a capacitor for charging a voltage supplied from a power supply and discharging the charged voltage when the power supply switch is turned off, and a grid control portion for supplying a grid terminal with the voltage outputted from the rectifying and smoothing portion when a power supply switch is turned on and for supplying the grid terminal with the voltage discharged from the capacitor plus the output voltage from the rectifying and smoothing portion when the power supply switch is turned off so that a spot can be prevented from appearing on a display screen when the power supply switch of the display device is turned off.
    Type: Grant
    Filed: December 29, 1995
    Date of Patent: October 28, 1997
    Assignee: Daewoo Electronics Co., Ltd.
    Inventor: Hyun-Gook Shin
  • Patent number: 5682087
    Abstract: A CRT compensation system (10) is disclosed which utilizes a cathode stabilizer circuit (16) to correct a cathode current I.sub.k which deviates from an ideal transfer function. The cathode stabilizer circuit (16) takes the cathode voltage V.sub.K and the cathode current I.sub.K and removes the ideal gamma transfer function from I.sub.K to produce a linear output. This linear output is then subtracted from the cathode voltage V.sub.K to produce an error voltage V.sub.err which is used to adjust the CRT drive to minimize the error in the cathode current. For example the V.sub.err the error voltage may be utilized to change the voltage level of the grid one element of the CRT (14). As a result, the CRT (14) will more closely approximate the ideal transfer function. The system (10) operates continuously and thus is able to correct for short term cathode current effects on a real time basis.
    Type: Grant
    Filed: October 2, 1995
    Date of Patent: October 28, 1997
    Assignee: Hughes-JVC Technology Corporation
    Inventors: John Jeffery Lyon, Richard Filia, Joe E. Deavenport
  • Patent number: 5677730
    Abstract: An improved spot elimination circuit for preventing a spot from occurring on the screen of a cathode ray tube such as a monitor or television receiver at the instant that the deflection circuit is shut off. An input voltage is charged and discharged to supply a high voltage in negative polarity to a first grid of the cathode ray tube. The spot elimination circuit includes a flyback transformer having a separate turns portion additionally provided for generating a high voltage and utilizes the high voltage as an input to thereby supply a cut-off voltage to the first grid. Accordingly, the phosphor screen of the cathode ray tube is protected from excessive cathode luminance at a focused spot which can cause degradation of the screen.
    Type: Grant
    Filed: September 29, 1995
    Date of Patent: October 14, 1997
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Tae-jin Park
  • Patent number: 5589883
    Abstract: A cathode ray tube display in which a signal for detection of a cathode current is inserted into a part of the vertical blanking period of the video signal to be displayed, a cathode current corresponding to the signal for detection is detected, and a cathode voltage or a grid voltage is negative feedback controlled so that the detected cathode current becomes constant, thereby stabilizing the cathode current. The display has a local overscan circuit for executing a vertical scan on the screen with a width larger than a predetermined scan width only at a timing of the cathode current detecting signal inserted for a vertical blanking period, and even in the case where an underscan system to scan by a width smaller than a predetermined display screen width is used as a scan system of the screen display. The invention prevents a harmful visible display image by the cathode current detecting signal appears on the screen.
    Type: Grant
    Filed: June 8, 1994
    Date of Patent: December 31, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Masanori Ogino, Takeo Yamada, Miyuki Ikeda, Tsuneo Fujikura, Takahiko Fujiwara, Etsuhiro Nakagiri
  • Patent number: 5463288
    Abstract: A screen grid voltage or a focus voltage for a cathode ray tube is controlled via a digital-to-analog converter. The voltage variation range of the screen grid or focus voltage that can be obtained for the entire variation range of an output signal of the digital-to-analog converter is not significantly larger than that required for the type of cathode ray tube that is utilized.
    Type: Grant
    Filed: September 3, 1993
    Date of Patent: October 31, 1995
    Assignee: Thomson Consumer Electronics, Inc.
    Inventors: John B. George, Lawrence E. Smith
  • Patent number: 5184225
    Abstract: A television receiver includes a high voltage kinescope driver amplifier having an input for receiving a video signal and a further input for receiving a character input signal from a low voltage character amplifier. When switching from a "run" mode to a "stand-by" mode, a control circuit generates a turn-off command signal for disabling the kinescope high voltage supply and concurrently initiating turn-off of the receiver deflection circuit at a controlled rate during a transition interval between the "run" and "standby" operating modes. The turn-off command is further applied during the transition interval to an input of the character amplifier so as to over-ride any character signal which may be present to drive the output of the character amplifier to a maximum brightness level which, in turn, over-rides any video signal applied to the high voltage amplifier.
    Type: Grant
    Filed: July 3, 1991
    Date of Patent: February 2, 1993
    Assignee: Thomson Consumer Electronics, S.A.
    Inventors: Wolfgang Heidebroek, Zeith W. C. Hsing
  • Patent number: 5130615
    Abstract: A source of switched supply voltage is applied to a potential divider and coupled to an output terminal via a capacitor. An output tap of the potential divider is coupled to the output terminal via the conduction path of a grounded base transistor. In operation the transistor (1) operates in an inverted mode for initially charging the capacitor, (2) operates in either a normal or an inverted mode for regulating a grid bias voltage at said output terminal for grid current flow of either direction relative to the output terminal and (3) operates in an isolation mode upon removal of the switched supply voltage whereby the capacitor applies a negative grid cut-off bias to the output terminal, said transistor in said isolation mode preventing discharge of the capacitor thereby providing a grid cut-off bias at said output terminal having an extended cut-off time constant due to the lack of any discharge path for the capacitor other than leakage.
    Type: Grant
    Filed: July 1, 1991
    Date of Patent: July 14, 1992
    Assignee: Thomson Consumer Electronics, Inc.
    Inventor: John B. George
  • Patent number: 5103145
    Abstract: A field emission cathode for use in a cathode-ray tube (CRT) includes groups of electron emission cells that produce different degrees of luminance on the phosphor-coated CRT screen. The cells replace the conventional CRT cathode and are fabricated on a planar surface. Each cell comprises a fixed number of discrete electron emitters, and the groups comprise different numbers of cells, typically in binary relation to one another. The cell groups of are interconnected via separate drive lines; each group is activated by applying voltage to its line. Different combinations of groups may be activated to achieve different brightness intensities on the CRT screen. A cathode having fifteen cells arranged in four groups (1, 2, 4 and 8 cells) is capable of producing sixteen shades of gray.
    Type: Grant
    Filed: September 5, 1990
    Date of Patent: April 7, 1992
    Assignee: Raytheon Company
    Inventor: Robert W. Doran
  • Patent number: 5089754
    Abstract: A circuit for protecting a cathode ray tube screen from damage by an electron beam includes a semiconductor switch device having an input coupled to a signal related to a deflection signal for the electron beam. The switch device is coupled to a voltage supply and the circuit further includes a charge storage device coupled to the switch device and further coupled to a control grid of the cathode ray tube. The charge storage device is charged through the switch device by the voltage supply when the deflection signal is present at a control input of the switch device. The switch device decouples the supply voltage from the charge storage device when the deflection signal is not present and places a negative blanking voltage developed on the charge storage device across the control grid when the deflection signal is not present to cut-off beam current in the cathode ray tube.
    Type: Grant
    Filed: April 30, 1990
    Date of Patent: February 18, 1992
    Assignee: Thomson Consumer Electronics, Inc.
    Inventor: John B. George
  • Patent number: 5084657
    Abstract: A spot killer circuit for a cathode ray tube having blanking function is configured to be provided with a positive voltage source, a negative voltage source, two diodes, condensers and a resistor in order to perform blanking in horizontal scanning or vertical scanning by using a first grid of the cathode ray tube. In the configuration, the two diodes are inserted in series between the negative voltage source and the first grid, and a first condenser is inserted between a junction of the two diodes and the positive voltage source. A resistor is connected in parallel with the diode connected to the first grid, and a blanking signal is applied to the first grid through a second condenser.
    Type: Grant
    Filed: April 10, 1991
    Date of Patent: January 28, 1992
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventor: Mitsunori Ueda