Patents Examined by Magdy W. Shehata
  • Patent number: 5479501
    Abstract: Method and apparatus for detecting a far-end disconnect signal for use by telephony applications such as voice messaging systems. In a preferred embodiment of the present invention, signal power of a telephone signal in particular frequency ranges is compared with the signal power in these frequency ranges for characteristic far-end disconnect signals used by telephone systems worldwide. Further, the cadence of the signal power of the telephone signal is examined to determine whether the cadence of the telephone signal is characteristic of far-end disconnect signals, including "busy signals" and "dial tones.
    Type: Grant
    Filed: October 8, 1993
    Date of Patent: December 26, 1995
    Assignee: Rolm Systems
    Inventor: Daniel T. Lai
  • Patent number: 5459783
    Abstract: An acoustic feedback suppression device, particularly for auxiliary ringers in plug-in telephone systems, includes diodes in addition to a rectifier bridge of the ringer. The circuit provides direct-current decoupling and limits the AC voltage present across the auxiliary ringer.
    Type: Grant
    Filed: February 16, 1993
    Date of Patent: October 17, 1995
    Assignee: SGS-Thompson Microelectronics S.A.
    Inventors: Pietro Consiglio, Carlo Antonini
  • Patent number: 5459786
    Abstract: Controlled by a signal level produced by a microphone (12), a noise suppressing circuit (25) supplies a first attenuator (16) with a local level which is equal to the signal level and is suppressed to a predetermined output level when the signal level is lower and higher than a predetermined input level. Cooperating with a drive level produced by a second attenuator (17) to drive a loudspeaker (13), the local level makes a comparator unit (21-23) produce a control signal for making the first attenuator give smaller and greater amounts of attenuation to the signal level with the drive level rendered by the second attenuator low and high when positive and negative values are had, respectively, by an input difference equal to the local level less the drive level. Preferably, the local level is suppressed by a level difference had by the signal level above the predetermined input level.
    Type: Grant
    Filed: November 22, 1994
    Date of Patent: October 17, 1995
    Assignee: NEC Corporation
    Inventors: Yutaka Tomiyori, Tadashi Eguchi
  • Patent number: 5446787
    Abstract: A method for avoiding self-oscillation in a four-wire loop in conjunction with echo cancellation is effected with the aid of an adaptive filter (15). Self-oscillation is avoided for both long and short connections and also when signalling with narrow-band signals, by restricting the permitted range of the coefficients of the adaptive filter in a manner such that the absolute value of the filter transfer function will be sufficiently small so that amplification in the four-wire loop is less than one. This is achieved by limiting the absolute value of the filter transfer function (1Hcal), to a value which is smaller than a determined function of the echo transfer function (H.sub.fa) in the far-end of the loop and the echo transfer function (H.sub.ne) in the near-end of the loop.
    Type: Grant
    Filed: April 8, 1993
    Date of Patent: August 29, 1995
    Assignee: Telefonaktiebolaget LM Ericsson
    Inventor: Bengt G. Lofmark
  • Patent number: 5444775
    Abstract: A locator aid for identifying and permitting the actuation of the number "9" and "1" keys of a rotary or touch telephone keyboard. Each locator includes a base which is fixedly positioned with respect to the telephone, an elongated guide strip, and an intermediate hinge connection between the base and the guide strip. Each base is positioned with respect to the telephone so its guide strip will lie in spaced relation to a finger hole of a rotary dial or in overlying relation to one of the keys of a keyboard. In a preferred construction the locator is constructed of a die cut plastic strip and includes multiple, bendable hinge joints and an adhesive fastener, which permits selective attachment of the locator to a phone body. In other constructions, the locator is integrally molded as an selectively attachable member or is molded as part of the keyboard.
    Type: Grant
    Filed: November 9, 1993
    Date of Patent: August 22, 1995
    Inventor: John J. Tobish
  • Patent number: 5438619
    Abstract: A telephone protector includes a rigid plastic packaged solid state switch which is clamped to prevent the switch from bursting to an open circuit condition.
    Type: Grant
    Filed: November 20, 1990
    Date of Patent: August 1, 1995
    Assignee: Siecor Puerto Rico, Inc.
    Inventors: William J. Shannon, John J. Napiorkowski, Dan Kidd
  • Patent number: 5410594
    Abstract: A transmission input/output device for signal transmission through a telephone line, with reduced power consumption, size, and cost. The device includes: a resistor, connected to the telephone line, for setting a signal input and output impedance; and a transmission control circuit for amplifying the transmission signals to be outputted to the telephone line, including: a variable resistor, connected in series with the resistor, for supplying voltages corresponding to the transmission signals to be outputted to the telephone line into the resistor according to changes of an impedance of the variable resistor; and an operational amplifier for controlling the changes of the impedance of the variable resistor by supplying an output according to the transmission signals to be outputted to the variable resistor.
    Type: Grant
    Filed: February 28, 1991
    Date of Patent: April 25, 1995
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Ryoji Maruyama
  • Patent number: 5295185
    Abstract: A ringing signal generation circuit contains a direct current power source, a transformer, a control transistor, a rectifying and smoothing circuit, an invertor circuit, and an invertor controlling circuit. The direct current power source generates a direct current voltage. The transformer contains a primary winding and a base-driving winding in a primary side, and a secondary winding in a secondary side. The control transistor is connected in series to the primary winding and the direct current power source, and controls a current flowing in the primary winding. The rectifying and smoothing circuit rectifies and smooths a current generated in the secondary winding. The invertor circuit for converting a direct current output of the rectifying and smoothing circuit into an alternating current. The invertor controlling circuit controls the invertor circuit.
    Type: Grant
    Filed: June 6, 1990
    Date of Patent: March 15, 1994
    Assignee: Fujitsu Limited
    Inventor: Toshihumi Washio
  • Patent number: 5241590
    Abstract: A device for dialing a preprogrammed telephone number is inserted between a cord connecting the handset and body of a telephone set and either the handset or the body. In order to provide an incentive for installing the device, it is preferably incorporated in a cord detangler having a jack for receiving one end of the cord and a relatively rotatable plug for insertion in a jack in the handset or body. A push button switch on the device activates the redial function of a DTMF tone generator chip which is connected electrically in parallel with the microphone conductor pair of the cord connection. A nonvolatile redial memory is provided, either by providing battery backup for the chip so as to retain a preprogrammed number in memory even when polarization current is not available to power the chip, or by providing a read-only redial memory.
    Type: Grant
    Filed: December 18, 1990
    Date of Patent: August 31, 1993
    Assignee: Dialing Devices Inc.
    Inventors: Darrell Deakins, John Bell
  • Patent number: 5235637
    Abstract: An apparatus 10 controls the two-way communication between the microphone 12 and speaker 36 of a telephone headset and a telephone base. A transmit channel 15 includes an expander 18 that controllably attenuates the transmitted communication signal when the user is not speaking into the microphone 12. Conversely, a receive channel 30 includes a compressor 34 that controllably attenuates the received communication signal to prevent over driving the speaker 36.
    Type: Grant
    Filed: February 13, 1992
    Date of Patent: August 10, 1993
    Assignee: Plantronics, Inc.
    Inventors: Vladimir Kraz, Paul Regen, Wayne Stade, Jeff Wimsatt, Robert Young
  • Patent number: 5228080
    Abstract: A method and apparatus for processing incoming telephone calls includes structure and process steps whereby an incoming telephone calling signal having a data message associated therewith is received. The data message is processed to determine whether it is a first type of message or a second type of message. An alert signal is output only if the received data message is determined to be a first type of message. Preferably, the alert signal is a ring signal, and the first type of message is an ICLID message indicating the identification of the telephone call initiator or calling party. If the incoming signal is detected as an ICLID PRIVATE signal, the phone ringer will not be activated, an off-hook signal will be returned to the caller, and a display device will indicate that the received call is an ICLID PRIVATE phone call.
    Type: Grant
    Filed: June 25, 1990
    Date of Patent: July 13, 1993
    Assignee: Colonial Data Technologies Corp.
    Inventors: William L. Nutter, Robert F. Wasco, Jonathan G. Berera
  • Patent number: 5226077
    Abstract: Existing automatic log on/log off systems in telephone systems determine whether or not a workstation is occupied, and that calls can be directed to that workstation, by determining whether or not the amplifier that provides the interface between the telephone system and the occupant's headset is plugged into the workstation. Recent headsets have a connector in the cord between the headset and the amplifier. This enables the occupant to leave the workstation without unplugging the amplifier, which defeats sensing mechanism of the existing automatic log on/log off system. An amplifier according to the invention replaces the existing amplifier and includes a detector that determines whether the headset is connected to the amplifier, and an activator that activates the existing automatic log on/log off system in the telephone system.
    Type: Grant
    Filed: March 2, 1992
    Date of Patent: July 6, 1993
    Assignee: ACS Communications, Inc.
    Inventors: Dwight D. Lynn, Kirk A. Reid, Shu-Ren Chen
  • Patent number: 5222129
    Abstract: Detector for telephone charging signalling in the form of periodic pulses derived from alternating current signals at specific frequencies transmitted in analog form by means of a line (2) comprising two wires (A, B), for example to a central office line interface circuit of a private telephone installation connected to an analog network subscriber line. The detector comprises an input filter (4) centered on the frequency (Ft) of the expected signalling, a sample and hold circuit (6) connected to the output of the input filter (4) and to the output of a clock (7) supplying a signal (HE) whose frequency (FE) is close to the value (Ft), a lowpass filter (8) within the band of which the characteristic signal from the sample and hold circuit is included, and a level detector (9) adapted to supply a presence signal for a characteristic signal at a level above a predetermined threshold at the output of the lowpass filter (8).
    Type: Grant
    Filed: June 19, 1990
    Date of Patent: June 22, 1993
    Assignee: Alcatel Business Systems
    Inventors: Andre Bonvallet, Robert Girard, Michel Canonne
  • Patent number: 5210785
    Abstract: This invention relates to a wireless communication system, which comprises plural wireless communication units having different communication protocols, and in which a proper wireless communication unit is automatically selected from the plural wireless communication units in accordance with the operation states of the plural wireless communication units to make communication possible. Thereby, troublesome operation is not required, an optimum wireless communication method can be automatically selected, and communication cost can be reduced. In the wireless communication system of the present invention, when mobile stations are registered in a fixed station, preferential orders of the mobile stations are stored, and calling/call-reception and communication processings are controlled according to the preferential orders.
    Type: Grant
    Filed: February 27, 1989
    Date of Patent: May 11, 1993
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hideaki Sato, Toshihiko Myojo
  • Patent number: 5199064
    Abstract: A single integrated circuit forms a hands-free telephone unit for use in a digital telephone network and in association with an external keypad, an external microprocessor, an external microphone, and an external speaker. The integrated circuit includes a keypad monitor arranged to provide digital key code signals, an audio processor for supporting hands-free operation, and a digital interface to provide a digital interface between the integrated circuit and the digital network and the external microprocessor.
    Type: Grant
    Filed: December 3, 1990
    Date of Patent: March 30, 1993
    Assignee: Advanced Micro Devices, Inc.
    Inventors: Dale E. Gulick, Herbert Chen, Alan F. Hendrickson
  • Patent number: 5177782
    Abstract: An entrance terminal and interface between the telephone company network and the subscriber's premises is more readily serviced by a single module having an enclosed printed circuit board combining the voltage overload device, the demarcation plug and socket and a service circuit such as a half-ringer or maintenance termination unit.
    Type: Grant
    Filed: August 30, 1990
    Date of Patent: January 5, 1993
    Assignee: Minnesota Mining and Manufacturing Company
    Inventors: Daniel H. Henderson, Charles W. Hoffman, Richard J. Scherer
  • Patent number: 5161183
    Abstract: An overvoltage protection circuit for a pair of conductors carrying a balanced signal includes two similar protection elements connected in series between the conductors and two equal value resistors respectively connected in parallel with the elements, so that the junction point of the two elements is at a voltage midway between the voltages on the conductors and the protection elements present equal capacitances to the conductors. A third protection element is connected from the junction point of the two elements to ground to protect against excessive voltages relative to ground on the conductors. The voltage division provided by the resistors may be adjusted to improve the balance of the capacitances presented by the two protection elements.
    Type: Grant
    Filed: September 21, 1989
    Date of Patent: November 3, 1992
    Assignee: Texas Instruments Incorporated
    Inventor: Michael Maytum
  • Patent number: 5159627
    Abstract: A sound generator is actuated by a trigger signal produced from a ringing signal on a telephone line, and a telephone line switching mechanism responds to the trigger signal from the trigger signal generator to disconnect the telephone set from the telephone line during an on state of the ringing signal and connect the telephone set to the telephone line during an off state of the ringing signal. Thus, the sound generator can be used to indicate the reception of a telephone call without actuating the telephone bell, and telephone communication is thereafter possible by hooking-off the telephone receiver. The line switching mechanism is preferably of a type which causes a telephone bell to ring upon a power source failure of the sound generator by connecting the telephone line to the telephone receiver.
    Type: Grant
    Filed: November 5, 1990
    Date of Patent: October 27, 1992
    Assignee: Sadao Kitazawa
    Inventor: Kiyoshi Hama
  • Patent number: 5131031
    Abstract: Modular hold circuits which may be independently connected to a telephone line and powered therefrom are provided in accordance with the teachings of the present invention. Hold circuits connectable to a telephone line in the same manner as a telephone instrument are employed to detect an actuating signal generated at any telephone instrument in an off-hook condition connected to that telephone line. Upon detection of such actuating signal, an impedance is placed across the telphone line to establish a hold condition. The hold condition established may be released by placing any telephone instrument connected to a telephone line in an off-hook condition, however, if the telephone line is provided with a "call waiting" feature, such off-hook condition must be maintained for an interval exceeding that associated with a "call waiting" signal for the hold condition to be released.
    Type: Grant
    Filed: August 24, 1989
    Date of Patent: July 14, 1992
    Inventor: Herbert Waldman
  • Patent number: 5131033
    Abstract: A sealing current generator for a telephone circuit provides a conventional nominal DC bias current in a telephone loop, and also temporarily provides a higher "zap" current whenever the DC current path is broken and then reapplied to the telephone loop. During the "zap" period, the voltage placed across the telephone loop is progressively increased in a number of predetermined steps if the current actually measured in the telephone loop fails to exceed a minimum value. The voltage is then maintained at its last level for the remainder of the "zap" period, after which the device returns to its base mode of providing a nominal DC bias current to the telephone loop.
    Type: Grant
    Filed: May 15, 1990
    Date of Patent: July 14, 1992
    Assignee: XEL Communications, Inc.
    Inventor: Peter M. Reum