Patents Assigned to Zenith Radio Corporation
  • Patent number: 4600921
    Abstract: The present invention permits a teletext system operator to adjust subscriber access to service levels individually by adjusting a code at the head end station. A head-end station transmits a tier description page and a tier authorization page. The tier description page divides the data base into a group of tiers each comprising a defined range of pages. The authorization page lists authorization codes for all subscribers, one code per subscriber. Each subscriber station includes a permanent location code. When access is requested by the subscriber, the subscriber station uses the location code to acquire the authorization code transmitted by the head-end station. The authorization code indicates which tiers the subscriber station may decode. To change the service, the system operator may change the authorization codes at the head-end station or change the range definitions for the service level tiers.
    Type: Grant
    Filed: October 19, 1983
    Date of Patent: July 15, 1986
    Assignee: Zenith Radio Corporation
    Inventor: William L. Thomas
  • Patent number: 4574277
    Abstract: A video display system utilizes three banks of memory for producing an 8-color or an 8-level gray scale display. A separate memory plane, or random access memory (RAM) array, for each of the "primary" video colors, i.e., red, green and blue, is used in a bit-mapped video graphics implementation for a computer driven video display. In a monochrome display, pixel mixing produces the 8-level gray scale display. Each of the video planes may be selectively disabled as desired for special applications. For example, a limited animation capability may be provided by displaying one page while generating a new page in a non-displayed page. By disabling the currently displayed plane as the new plane is enabled, instantaneous page modification may be closely simulated for animated applications. The thus disabled video plane may then be used as any normal page of RAM for any other application.
    Type: Grant
    Filed: August 30, 1983
    Date of Patent: March 4, 1986
    Assignee: Zenith Radio Corporation
    Inventors: Charles A. Krause, Babu Rajaram
  • Patent number: 4554581
    Abstract: An addressable subscription television decoder includes an input stage including an IF amplifier for converting a scrambled RF television signal to a composite baseband video signal. The baseband video signal comprises either a nominal sync component or a sync component having suppressed horizontal sync pulses during video fields and having non-suppressed sync pulses during vertical intervals, the vertical intervals also including selected encoded data signals. An AGC voltage for controlling the gain of the IF amplifier is developed by a circuit exhibiting a relatively short time constant whenever the composite baseband video signal is characterized by nominal level sync pulses, the time constant being increased in response to suppressed horizontal sync pulses. The sync pulses produced during the vertical intervals of the composite baseband video signal are thereby not subjected to excessive IF gain for facilitating processing of the data signals by the decoder.
    Type: Grant
    Filed: February 14, 1985
    Date of Patent: November 19, 1985
    Assignee: Zenith Radio Corporation
    Inventors: Michael Tentler, David L. Walker, Wayne E. Bretl, Gregory A. Williams
  • Patent number: 4518997
    Abstract: A television receiver includes an integrated circuit audio system suitable for stereo sound, and a source of angle-modulation audio waves supplied from a limiter/integrator to a differential amplifier detector. A series parallel arrangement of elements in a first phase shift network has the parallel connected elements coupled across the inputs of the differential amplifier detector. A second phase shift network, coupled directly across the limiter/integrator output, loads the first phase shift network and linearizes the audio system output over a large signal deviation. The output of the differential amplifier detector supplies the detected audio output.
    Type: Grant
    Filed: January 13, 1983
    Date of Patent: May 21, 1985
    Assignee: Zenith Radio Corporation
    Inventor: Orval E. Beckman
  • Patent number: 4489347
    Abstract: A decoder includes an oscillator supplying a decoding signal to the control input of an RF modulator for decoding a sine wave encoded television signal. The decoding signal developed by the oscillator is randomly phase locked in either of two states with the output of a horizontal sync separator operated in response to the detected output of the RF modulator. In the first phase locked state, the decoding signal is in antiphase relationship with the encoding modulation resulting in a properly decoded baseband video signal. In the second phase locked state, the decoding signal is in phase alignment with the encoding modulation so as to constructively combine therewith. The second phase locked state is detected and broken each time it is assumed allowing the decoder to eventually assume the first phase locked state wherein a properly decoded video signal is produced.
    Type: Grant
    Filed: August 30, 1982
    Date of Patent: December 18, 1984
    Assignee: Zenith Radio Corporation
    Inventor: Michael Tentler
  • Patent number: 4460995
    Abstract: A compensation scheme is disclosed which avoids the requirement of high alignment accuracy, and thus reduces the production cost of a surface acoustic wave filter, by employing a compensating transducer system which is arranged with its fingers parallel to those of the receiving transducer. The requirement of receiver sensitivity at the trap frequencies is nevertheless achieved by using a very narrow compensating beam width. The narrowness of the compensating beam also allows it to pass directly through a multi-strip coupler. The degree of compensation achieved is controlled by aiming the compensating beam at a small region of the apodized receiving transducer located at the extremity of the major lobe; by restricting the aperture of the compensating transducer system; and by trimming the printed circuit capacitor which couples the compensating transducer system to the electrical input signal.
    Type: Grant
    Filed: April 21, 1982
    Date of Patent: July 17, 1984
    Assignee: Zenith Radio Corporation
    Inventor: Adrian J. DeVries
  • Patent number: 4461041
    Abstract: The front end of a microwave receiver includes a waveguide with one wall comprised partially of the conductive ground plane of a printed circuit board. On the opposite side of the circuit board is mounted receiver front end circuitry including packaged, discrete devices and integrated circuits. An RF probe is inserted through the circuit board and into the waveguide for picking up a signal incident thereon and providing it to the aforementioned receiver front end circuitry. Incorporated in the waveguide is a cavity also partially formed from the ground plane of the receiver circuit board and containing a dielectric resonator element which, in combination with an oscillator located on the circuit board, provides a reference frequency for mixing with the received signal in generating an IF signal which is then provided to IF signal processing circuitry.
    Type: Grant
    Filed: January 5, 1983
    Date of Patent: July 17, 1984
    Assignee: Zenith Radio Corporation
    Inventor: Pierre Dobrovolny
  • Patent number: 4461040
    Abstract: In an RF receiver, the unsymmetric RF input to a single balanced mixer is provided from the preceding portion of the receiver by means of a hybrid coupler to provide DC decoupling and impedance transformation at the RF and image frequencies. The hybrid coupler includes first and second microstrip conductors on the first side of a circuit board, each respectively coupled to the preceding portion of the receiver such as to a preamplifier and to the mixer and mutually electromagnetically coupled. On a second side of the circuit board is located a slot etched in the circuit board's conductive ground plane providing the single balanced mixer with a symmetric oscillator frequency source. The ground plane in which the slot is located forms one wall of a cavity in which a dielectric resonator is contained which, coupled to either end of the slot and in combination with an active device, forms the oscillator frequency source.
    Type: Grant
    Filed: January 6, 1983
    Date of Patent: July 17, 1984
    Assignee: Zenith Radio Corporation
    Inventor: Pierre Dobrovolny
  • Patent number: 4461032
    Abstract: A remotely located and controlled programming controller for a cable-compatible television receiver is disclosed. Cable head end-generated control signals are provided by wire to the cable TV controller for selectively enabling the reception of subscribed-to CATV channels by the television receiver. Coded subscriber addressing and operating mode control signals are provided to each controller in the cable network for selectively enabling/disabling each controller for limiting cable programming distribution. Each controller is responsive to transmitted operating mode control data bits for enabling/disabling individual cable channel reception. In addition, each controller is assigned and responsive to subsequently transmitted, uniquely coded address identifier data bits. Operating mode control and address data are represented respectively by the first and last bit groups of the head end-generated cable access signal.
    Type: Grant
    Filed: June 21, 1982
    Date of Patent: July 17, 1984
    Assignee: Zenith Radio Corporation
    Inventor: Peter C. Skerlos
  • Patent number: 4459476
    Abstract: The invention is directed to an X-Y co-ordinate detection system of the type which generates intersecting paths of radiation across a surface which may be, for example, a touch panel of the cathode ray tube type. Less expensive and more reliable operation is provided by developing the paths of radiation by use of radiation-emissive material disposed near at least one edge of the surface and excited by a flying spot of energy, such as an electron beam. In the preferred embodiment, strips of infrared emissive material are disposed on an internal surface of a cathode ray tube's panel and excited by overscanning the tube's electron beam to develop intersecting paths of infrared radiation across the tube's faceplate.
    Type: Grant
    Filed: January 19, 1982
    Date of Patent: July 10, 1984
    Assignee: Zenith Radio Corporation
    Inventors: William W. Weissmueller, James Fitzgibbon
  • Patent number: 4457733
    Abstract: A television cathode ray picture tube has an in-line electron gun for generating three coplanar electron beams. The raster pattern projected by the center beam is diminished in vertical height so as to be non-coextensive with the superimposed raster patterns projected by the off-axis beams. The method according to the invention for providing raster coextensiveness comprises embracing each off-axis beam at the point of beam egress from the gun with a pair of inwardly converging but non-intersecting magnetic field enhancer means in symmetrical relationship and defining an opening therebetween. Each member of the enhancer means is oriented at a predetermined convergence angle with respect to the plane of the three beam paths, and located at a predetermined distance from the tube axis.
    Type: Grant
    Filed: April 27, 1982
    Date of Patent: July 3, 1984
    Assignee: Zenith Radio Corporation
    Inventors: Norman F. Gioia, Fred H. Seher
  • Patent number: 4458268
    Abstract: A subscription television system comprises means for broadcasting a scrambled television signal wherein the NTSC horizontal and vertical synchronization signals are displaced in time from their nominal positions. Each authorized system subscriber is provided with a decoder adapted for restoring the synchronization signals to their nominal positions to enable unscrambling of the broadcast programs for viewing. The synchronizing signals may be time displaced in a static manner or the time displacement may be dynamically varied as a function of time.
    Type: Grant
    Filed: January 8, 1982
    Date of Patent: July 3, 1984
    Assignee: Zenith Radio Corporation
    Inventor: Walter Ciciora
  • Patent number: 4456925
    Abstract: A television receiver incorporating telephone interface circuitry permitting the viewer to remotely place outgoing calls by recalling a selected number from memory is disclosed. An infrared link is used for remotely answering incoming calls, initiating outgoing calls and programming a nonvolatile memory with a plurality of preferred telephone numbers for future use. The nonvolatile memory circuit is accessed by means of a microcomputer in response to user-initiated, remotely generated commands. The television receiver's display performs a user interactive function in displaying television/telephone mode operation information, the contents of user-accessed locations in the nonvolatile memory and the telephone number being stored in memory during the programming mode of operation.
    Type: Grant
    Filed: October 4, 1982
    Date of Patent: June 26, 1984
    Assignee: Zenith Radio Corporation
    Inventors: Peter C. Skerlos, Thomas J. Zato, Frank C. Templin
  • Patent number: 4454572
    Abstract: A flyback transformer is described for use in television receivers, video monitors, and the like in which a video display device is scanned in accordance with a horizontal retrace frequency. The transformer includes a primary winding for receiving horizontal scan rate pulses and a plurality of secondary windings. The latter windings are tuned to selected harmonics of the horizontal retrace frequency such that at least two secondary windings develop horizontal rate pulses whose peaks are complimentary. The pulses developed by the secondary windings are combined so as to develop a composite pulse whose peak is substantially flat.
    Type: Grant
    Filed: May 27, 1982
    Date of Patent: June 12, 1984
    Assignee: Zenith Radio Corporation
    Inventor: Theodore J. Godawski
  • Patent number: 4453153
    Abstract: A bleeder resistor is described for draining charge from capacitances formed in a three element isolator. The isolator includes a dielectric element having conductive coatings thereon to form a capacitance. A bleeder resistor is formed on the dielectric element by screening a thick film resistive composition on the dielectric element so as to create a discharge path between conductive coatings on the dielectric element.
    Type: Grant
    Filed: May 10, 1982
    Date of Patent: June 5, 1984
    Assignee: Zenith Radio Corporation
    Inventors: Raymond G. Capek, Elgie Garrett
  • Patent number: 4450386
    Abstract: An electronic image framing circuit is described for eliminating the visible effects of pincushion distortion at the edges of a television image. Toward this end, portions of video lines which extend beyond a selected straight line image boundary are blanked by a pulse processor. The pulse processor responds to conventional horizontal rate and vertical rate pulses for developing blanking pulses whose widths are varied at a vertical rate. The modified blanking pulses are applied to a conventional blanking circuit for blanking the portions of video lines which extend beyond the desired image area. A parabola generator is also described for use in developing the modified blanking pulses.
    Type: Grant
    Filed: November 30, 1981
    Date of Patent: May 22, 1984
    Assignee: Zenith Radio Corporation
    Inventor: Stanley E. Lehnert
  • Patent number: 4449145
    Abstract: An equalizer and decoder system compensating for multipath distortion in digital format signals sent by teletext, for example. The system loads demodulated data signals and a received reference signal into a charge coupled device clocked in real time by a clock circuit. Later, the reference pulse is clocked to a microprocessor which determines tap coefficients for a transversal filter to correct the multipath distortion in the reference signal. The data signals are then applied to a transversal filter weighted with the calculated tap weights. After filtering, signals are decoded by the microprocessor.In another embodiment a charge coupled device with tapped stages is used at one time for receiving the data signals in real time, and at a later time for part of a transversal filter.In a simplest embodiment, distortions are removed by the microprocessor itself, without any separate transversal filter.
    Type: Grant
    Filed: June 13, 1983
    Date of Patent: May 15, 1984
    Assignee: Zenith Radio Corporation
    Inventor: Walter S. Ciciora
  • Patent number: 4446443
    Abstract: An integratable amplifier is disclosed for developing a high level output signal with reduced power dissipation. The amplifier includes a first circuit (108, 110) which responds to an input signal for developing first and second signal currents whose amplitudes increase and decrease, respectively, in response to an input signal transition of a given direction. A second circuit (32a) receives the first signal current for establishing a third signal current which mirrors the first signal current. The second and third signal currents are received by a third circuit (70a) for conversion thereof to an amplified output signal. To stabilize the gain of the amplifier, a negative feedback path (50a) is coupled between the input signal and the output signal.
    Type: Grant
    Filed: May 20, 1982
    Date of Patent: May 1, 1984
    Assignee: Zenith Radio Corporation
    Inventors: Fred D. Johnson, Michael D. Flasza, George J. Tzakis
  • Patent number: D275952
    Type: Grant
    Filed: March 1, 1982
    Date of Patent: October 16, 1984
    Assignee: Zenith Radio Corporation
    Inventors: Melvin H. Boldt, deceased, by Melvin W. Boldt, executor, David P. Chuboff, Wayne J. Franek
  • Patent number: D275953
    Type: Grant
    Filed: March 1, 1982
    Date of Patent: October 16, 1984
    Assignee: Zenith Radio Corporation
    Inventors: Melvin H. Boldt, deceased, by Melvin W. Boldt, executor, David P. Chuboff, Arnold Goldman, Wayne J. Franek