Cathode-ray Tube Display Beam Current Control Patents (Class 348/380)
  • Patent number: 6097445
    Abstract: A color display with a white balance self-adjusting function, including a DC-voltage-level/gain adjusting circuit for adjusting, on the basis of adjustment data, the DC voltage level and the gain of each of R, G and B primary color signals, thereby outputting the adjusted signals. Also includes is a CRT driving circuit responsive to the output signals of the DC-voltage-level/gain adjusting circuit for outputting CRT driving signals to drive the color CRT of the display, and a cathode current detecting circuit for detecting currents flowing through the cathode electrodes of the color CRT.
    Type: Grant
    Filed: March 28, 1997
    Date of Patent: August 1, 2000
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kenji Goto, Hiroshi Karasuda, Takeo Hagiwara
  • Patent number: 6072546
    Abstract: A correct estimation of a focussed condition of the cathode ray tube can be performed. A predetermined image (14) is displayed at a predetermined position on a screen of a cathode ray tube. A focussing voltage of the cathode ray tube is varied in a condition that a distance from a reference position to a predetermined position in the image is detected. When the changing state of the detected distance is displayed on a predetermined display means (11a), an optical low pass filter is arranged in the optical system such as the incident part of a sensor (15) or the like. From an output of the sensor (15), a condition is determined as the just-focussed condition, the under-focussed condition or the over-focussed condition and the beam spot diameter is calculated from the detected line width. On the basis of the decision of the under-focussed or the over-focussed condition and the calculated value of the beam spot diameter, a focus quantitative value is obtained.
    Type: Grant
    Filed: August 28, 1997
    Date of Patent: June 6, 2000
    Assignee: Sony Corporation
    Inventor: Tomoyasu Nakayabu
  • Patent number: 6064434
    Abstract: In a beam current measurement device, including an output transistor (T1) for supplying a cathode current (Ic), a measurement output (OUTM) for supplying a measured current (Im) representing the cathode current (Ic), a first current source (Ibias1) coupled to a first main terminal of the output transistor (T1) for supplying a first current (Ibias1), and a second current source (Ibias2) coupled to a second main terminal of the output transistor (T1) for supplying a second current (Ibias2) substantially equal to the first current (Ibias1), a first cascode transistor (Ta) is coupled between the first main terminal of the output transistor (T1) and the measurement output (OUTM).
    Type: Grant
    Filed: February 3, 1997
    Date of Patent: May 16, 2000
    Assignee: U.S. Philips Corporation
    Inventor: Pieter Van Der Zee
  • Patent number: 6040664
    Abstract: In a television receiver, a higher beam current is enabled and a brighter image is provided, without adversely effecting the life of the cathode ray tube or endangering the high-tension transformer. The high-tension transformer includes a temperature sensor which acts with a control circuit for reducing the beam current when the temperature of the transformer rises above a specific temperature.
    Type: Grant
    Filed: February 25, 1998
    Date of Patent: March 21, 2000
    Assignee: Deutsche-Thompson Brandt GmbH
    Inventors: Franz Dieterle, Martin Laufer
  • Patent number: 6034729
    Abstract: A monitor protection system comprise a display power management signaling (DPMS) operating unit for performing a predetermined power control; a horizontal deflection detecting circuit for detecting a horizontal deflection signal from a horizontal deflection circuit; a vertical deflection detecting circuit for detecting a vertical deflection signal from a vertical deflection circuit; and a control circuit for determining whether the horizontal deflection signal and the vertical deflection signal are normal, and generating a predetermine control signal to run the DPMS operating unit in order to observe the conditions of horizontal/vertical synchronization signals continuously, and protect a CRT monitor independently from the horizontal/vertical synchronization input conditions.
    Type: Grant
    Filed: October 17, 1997
    Date of Patent: March 7, 2000
    Assignee: SamSung Electronics Co., Ltd.
    Inventor: Joon-Woo Lim
  • Patent number: 6008842
    Abstract: A protective circuit and a signal processor for a three-CRT projection TV for preventing CRT burnout, deterioration of luminous characteristics, and damage to lenses by heat. Each CRT beam current detection circuit detects the beam current of each CRT. A state of the video image is predicted based on the detected beam current values and their duration. A microcomputer determines a control voltage for controlling the contrast based on the state of the video image, detected values, and their duration. The contrast is thus controlled by a control signal output to a video control circuit which controls the beam current.
    Type: Grant
    Filed: April 18, 1997
    Date of Patent: December 28, 1999
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventor: Koichiro Nagata
  • Patent number: 5977711
    Abstract: The present invention relates to a method and system for optimizing the output of at least two electron guns in a cathode ray tube for aging the cathode ray tube during manufacture. The system comprises at least two electron guns located in the cathode ray tube and a memory configured to store an offset value that is representative of a difference between a maximum output level and a detected output level for each of the electron guns. The system further comprises a processor coupled to the memory. The processor generates a first scaled signal by adding a first signal representative of an input voltage corresponding to the detected output level of the first electron gun and an offset signal representative of the offset value, and a second scaled signal by adding a second signal representative of an input voltage corresponding to the detected output level of the second electron gun and the offset signal.
    Type: Grant
    Filed: October 27, 1997
    Date of Patent: November 2, 1999
    Assignees: Sony Corporation, Sony Electronics, Inc.
    Inventors: Vincent Van Du, Hiroyuki Nakazono, Alexander McElroy
  • 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: 5892544
    Abstract: The present invention relates to a beam current control system for detecting and controlling a beam current generated by a cathode ray tube. The system comprises a video processing circuit that receives a first signal, and which generates a second signal that includes a video signal and a synchronization signal, which is provided to the cathode ray tube. The cathode ray tube generates a beam current corresponding to the second signal, where the beam current has a video signal portion and a synchronization signal portion. A storage element coupled between the video processing circuit and the cathode ray tube clamps the second signal at a first predetermined level, and stores an electrical charge corresponding to the video signal portion of the beam current during a first time interval.
    Type: Grant
    Filed: September 15, 1997
    Date of Patent: April 6, 1999
    Assignees: Sony Electronics, Inc., Sony Corporation
    Inventors: Hiroyuki Ikegami, Taro Tadano
  • Patent number: 5889557
    Abstract: An automatic beam current limiting apparatus for limiting beam currents of R, G, and B colors separately without affecting the the CRT drive. In particular, the Average Picture Level (APL) of each of the R, G, and B color video signals at the preceding stage of a video power amplifier is detected and compared with a reference voltage. When the APL of the video signal is higher than the reference voltage, the amplitude of the video signal is controlled to limit the beam current driving the CRT. In addition, the G1 voltage, and G2 voltage may be compared with a reference voltage and a result calculated by the APL calculating circuit. When the result is higher than the reference voltage, the amplitude of the video signal is controlled to limit the beam current driving the CRT.
    Type: Grant
    Filed: May 22, 1997
    Date of Patent: March 30, 1999
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventor: Hiroaki Sato
  • Patent number: 5889558
    Abstract: An image display is disclosed, in which a reference signal is superimposed on image signal in a fly-back period for controlling the bias voltage on the cathode of the CRT or the reference signal or the bias voltage on the grid G2 of the CRT such as to make the beam current in the CRT cathode to be constant by detecting the beam current in the reference signal period, while also obtaining brightness control. The image display comprises a stub pulse generator 2 for providing a stub on the black level side more than the image signal pedestal level, and an adder 3 for superimposing the stub pulse on the image signal. It is possible to change the reference signal voltage level to be on the black level side more than the image signal pedestal level, extend the brightness range, and obtain back luster float-up.
    Type: Grant
    Filed: October 31, 1997
    Date of Patent: March 30, 1999
    Assignee: NEC Corporation
    Inventor: Hiroaki Ikeda
  • Patent number: 5793448
    Abstract: A cathode ray tube package includes a cathode ray tube assembly and a housing assembly including a deflection coil and/or at least one focus coil. The cathode ray tube assembly includes a collar (31) aligned with the electron beam, being arranged to mate with a mounting collar (41) carried on the housing assembly. The provision of the collar (31) enables the cathode ray tube assembly to be easily replaced at the end of the cathode ray tube's life within the housing assembly without the need for realignment of the coils.
    Type: Grant
    Filed: September 26, 1995
    Date of Patent: August 11, 1998
    Assignee: Brimar Limited
    Inventors: George David Atkinson, James Francis Nangle
  • Patent number: 5784106
    Abstract: A method for improving brightness uniformity reduces a decrease of light towards the edges of a display screen (10) of a display tube (1). The extent of the decrease of light particularly depends on an increase of the thickness of the glass of the display screen (10) from the center of the display screen (10) to its edges, and on a transmission of the glass. This decrease of light is corrected by causing the deflection rate to decrease (C1, Cs) from the center of the display screen (10) towards its edges.
    Type: Grant
    Filed: April 30, 1996
    Date of Patent: July 21, 1998
    Assignee: U.S. Philips Corporation
    Inventor: Albertus A. S. Sluyterman
  • Patent number: 5764002
    Abstract: A horizontal deflection circuit includes circuitry for protecting the horizontal output transistor from failure due to an over-current condition. The circuitry includes a current detector for detecting the current in the collector-emitter path of the horizontal output transistor, and a interrupter for interrupting the drive signal to the horizontal output transistor when the detected current exceed a predetermined level.
    Type: Grant
    Filed: July 1, 1996
    Date of Patent: June 9, 1998
    Assignee: U.S. Philips Corporation
    Inventor: James R. Jennings
  • 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: 5680173
    Abstract: A complementary push-pull emitter follower amplifier is coupled between the output of a high voltage driver amplifier and the cathode of a kinescope for reducing the effective capacitance presented to the driver amplifier that is attributable to the kinescope cathode, socket, spark gaps and related stray capacitances. A secondary undesired capacitance loading of the amplifier attributable to the collector to base capacitances of the follower amplifier is effectively reduced by regulating the collector emitter voltages of the push-pull follower output transistors at respective substantially constant values thereby improving parameters such as the slew rate and bandwidth of the overall video display system.
    Type: Grant
    Filed: June 23, 1995
    Date of Patent: October 21, 1997
    Assignee: Thomson Consumer Electronics, Inc.
    Inventors: Charles Michael White, Jeffery Basil Lendaro
  • Patent number: 5671016
    Abstract: In a high voltage discharge circuit for a CRT, a power-off detecting circuit detects turning off of a power switch and outputs a power-off detection signal, to activate a luminance increasing section to increase the luminance of a video signal being outputted to the CRT at the time the power switch is turned off. Therefore, the high-voltage charges that remain applied between the anode and the cathode of the CRT after the power switch has been turned off discharge rapidly so that occurrence of afterglow can be reliably prevented.
    Type: Grant
    Filed: January 13, 1995
    Date of Patent: September 23, 1997
    Assignee: Funai Electric Co., Ltd.
    Inventor: Hirotsugu Suzuki
  • 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: 5555026
    Abstract: A video state stabilization apparatus for use in a video display unit for displaying a sub-picture within a main picture. The video state stabilization apparatus receives a main picture ABL control signal, and has a sub-picture beam current detector for generating a sub-picture ABL control signal by receiving a sub-video signal, and using an integrator and a differential amplifier, a switching portion for outputting the sub-picture ABL control signal and the main picture ABL control signal in response to a respective interval of the sub-picture and the main picture, and an adjuster for separately adjusting a brightness of a video signal of the main picture and of the subpicture, so as to make a PIP image with respect to the main picture and the sub-picture according to the ABL control signals output from the switching portions.
    Type: Grant
    Filed: December 7, 1994
    Date of Patent: September 10, 1996
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Kab-keun Lee
  • Patent number: 5548341
    Abstract: A picture in picture (PIP) video signal is applied to a display device via a non-linear processor that is enabled during display of a main picture component and disabled during display of an inset picture component responsive to a PIP identification signal. The non-linear processor is formed in an integrated circuit which includes a pin for connection to a capacitor that stores peak levels of the PIP video signal. The PIP identification signal is subjected to a voltage level translation for varying the pin voltage over a range of values, .DELTA.V, for facilitating ON/OFF operation of the non-linear processor and is applied to a selected plate of the capacitor for varying the pin voltage without substantial alternation of charge stored within the capacitor whereby only a single pin is required for both capacitor storage and on/off control of the non-linear processor and undesirable visual artifacts, such as "trailing contrast bars", are avoided.
    Type: Grant
    Filed: August 5, 1994
    Date of Patent: August 20, 1996
    Assignee: Thomson Consumer Electronics, Inc.
    Inventors: Kristopher A. Klink, Gene K. Sendelweck
  • Patent number: 5493336
    Abstract: For preserving and, thus, for extending the useful life of a picture tube of a picture tube screen device having a waiting state function. The filament current of the picture tube in the waiting state of the picture tube screen device is reduced by at least a slight percentage of an original filament current. Also, the picture tube is supplied with another video signal, in addition to an original video signal, that generates a beam current in the picture tube having a white image level that is at least a slight percentage of an original white image level generated by the original video signal.
    Type: Grant
    Filed: May 10, 1994
    Date of Patent: February 20, 1996
    Assignee: Siemens Nixdorf Informationssysteme AG
    Inventors: Wolfgang Racek, Edmund Poetsch, Josef Meinerzhagen, Erwin Baessler
  • Patent number: 5440210
    Abstract: A beam current limiter for sensing and limiting the beam current in a particle accelerator, such as a cyclotron or linear accelerator, used in scientific research and medical treatment. A pair of independently operable capacitive electrodes sense the passage of charged particle bunches to develop an RF signal indicative of the beam current magnitude produced at the output of a bunched beam accelerator. The RF signal produced by each sensing electrode is converted to a variable DC voltage indicative of the beam current magnitude. The variable DC voltages thus developed are compared to each other to verify proper system function and are further compared to known references to detect beam currents in excess of pre-established limits. In the event of a system malfunction, or if the detected beam current exceeds pre-established limits, the beam current limiter automatically inhibits further accelerator operation.
    Type: Grant
    Filed: April 16, 1993
    Date of Patent: August 8, 1995
    Assignee: University of Chicago
    Inventors: John M. Bogaty, Benny E. Clifft, Lowell M. Bollinger
  • Patent number: 5367231
    Abstract: The life time of a CRT is extended by decreasing the temperature of the cathode by 7-30% from the normal operating temperature and by applying a constant voltage signal to a cathode of the CRT which is shifted from a first voltage level for displaying the lowest luminance of the image toward a second voltage level for displaying the highest luminance of the image. The shift is of the order of 5-25%, so that a constant anode current in the range of 2-14 uA flows in the CRT.
    Type: Grant
    Filed: April 27, 1993
    Date of Patent: November 22, 1994
    Assignee: International Business Machines Corporation
    Inventors: Masaki Kobayashi, Rieko Kataoka
  • Patent number: 5345267
    Abstract: A receiver includes a kinescope, a driver amplifier and an integrated automatic kinescope bias (AKB) circuit. A soft start circuit includes a timing capacitor, external to the integrated circuit, and a control circuit within the integrated circuit which limits the AKB current adjustment range during turn-on to a time determined by the external capacitor. The capacitor is effectively isolated from the integrated circuit to prevent discharge thereof by protection diodes of the IC whereby the time constant of the overall AKB circuit is substantially the same for both hot start conditions and cold start conditions thereby avoiding undesirable visual start-up artifacts such as black level and contrast shifts during warm-up of the kinescope for either a cold start condition or a hot start condition.
    Type: Grant
    Filed: August 31, 1993
    Date of Patent: September 6, 1994
    Assignee: Thomson Consumer Electronics, Inc.
    Inventor: Andrew K. Flickner
  • Patent number: 5337090
    Abstract: A video output circuit of a wide bandwidth comprises a bridged-T-type circuit, a first inductor connected in series to the bridged-T-type circuit, and a shunt circuit connected in series to the bridged-T-type circuit and including a second inductor and a first resistor connected in parallel with each other. The bridged-T-type circuit, the first inductor and the shunt circuit cooperate to constitute together with a plurality of stray capacitors a low-pass filter whose order is at least 4 and whose merit index is at least 3.
    Type: Grant
    Filed: December 4, 1992
    Date of Patent: August 9, 1994
    Assignee: Hitachi, Ltd.
    Inventors: Masanori Ogino, Takeo Yamada, Miyuki Ikeda, Tsuneo Fujikura, Takahiko Fujiwara
  • Patent number: 5313294
    Abstract: An automatic beam current limiting arrangement of a television receiver or display monitor comprises an average beam current limiter coupled to the low side of the high voltage transformer for reducing the contrast of a reproduced image when the average beam current exceeds a threshold and a peak current limiter coupled to the cathodes of the picture tube for controlling a current source which determines the threshold of the average beam current limiter in response to the sum of the cathode currents of the picture tube. In one embodiment, the cathode current sensing circuits comprise the same cathode current sensing circuits utilized in an automatic black level setting arrangement. This beam limiting arrangement allows operation at high contrast levels while inhibiting excessive peak white areas.
    Type: Grant
    Filed: January 14, 1992
    Date of Patent: May 17, 1994
    Assignee: RCA Thomson Licensing Corporation
    Inventor: Peter E. Haferl
  • Patent number: 5294985
    Abstract: A limiter circuit responds to an input signal which has a plurality of frequencies within a given band. The input signal is split up into two frequency ranges by means of a low pass filter for one range and a high pass filter for a second range. The output of the low pass filter is directed to a first limiter while the output of the high pass filter is directed to a variable notch filter. The outputs from the first limiter and the notch filter are added together to provide a sum signal. The sum signal is applied to a second limiter which performs limiting strictly according to the amplitude. The outputs of the second limiter signal provide the desired signal and a control signal to determine how often the second limiter is limiting. The control signal varies the attenuation of the notch filter. In this manner frequencies, within a selective range and which will be otherwise effected by the spurious frequencies generated during limiting, are reduced.
    Type: Grant
    Filed: August 21, 1992
    Date of Patent: March 15, 1994
    Assignee: Deutsche ITT Industries GmbH
    Inventors: Hans-Juergen Desor, Heinrich Koehne