Abstract: In a radio paging receiver which is capable of responding to a message signal specific to the receiver and which comprises a display unit (90) and a message processing section (60) for making the display unit display the message signal, the message processing section monitors the message signal to produce a drive signal after reception of the message signal until the message signal is delivered to the display unit. Responsive to the drive signal, a combination of transistors (3 and 2) keeps power supply of a power source 18 to the message processing section as long as the drive signal is produced. Such power supply is carried out regardless of a state of a power supply switch (20). A decoder (40) makes a speaker (80) generate an alarm in response to the drive signal after the power supply switch is put into an off state. The alarm lasts until the switch is put into an on state.

Abstract: A pager has a receiver for receiving selective paging numbers and message data and a message display panel for displaying paging messages to the user. The pager has a first memory for storing message data. Control data, arriving together with the message data and related to its display, is stored in a second memory. A display controller, responsive to external operating inputs from the user, is provided for controlling the contents of the messages to be displayed on a basis of the control data. A display responds to control from the display controller, to read out and display messages stored in the first memory.

Abstract: A radio paging system, comprising a transmitting base station and a paging receiver with a battery-saving function. The paging receiver operates intermittently at different repetition periods, depending on the call traffic density. When there are fewer calls, the receiver operates less frequently, in order to avoid unnecessary operation and consequent battery drain. When there is a call to be sent, the period between attempted detections of a preamble code word is shortened. The receivers then lengthen the period for detecting a message, and receive a sync code word, followed by an address code word, which alerts the particular receiver being paged, an alert tone being generated. The message ends with a battery saving code word and ending code word. The battery saving code word alerts the receivers to lengthen the period between attempted detections of the preamble code word. The variation in length of periods between attempted detection is a battery-saving feature.

Abstract: A DC-DC converter having a high conversion efficiency and stable output voltage. A constant current supply circuit, located between the output terminals of the converter, make it possible for the source current to decrease as a function of battery output voltage, resulting in lower current requirements for a lower required voltage boost and hence increased efficiency.

Abstract: In a radio paging method of transmitting message information from a subscriber's substation (32) through a base station (30) to pager receivers (31) in the form of a radio calling signal, the message information is divided into a plurality of species to which key codes are assigned, respectively. When a selected one of the key codes is indicated from the substation prior to transmission of the message information, the base station sends a request to the substation in compliance with the selected key code to receive, as the message information, a message indicated by the request. The indicated message preceded by the selected key code is carried from the base station to the pager receivers by the radio calling signal. Each pager receiver reproduces the indicated message with reference to the selected key code. The substation comprises a push-button telephone set to send each message to the base station.

Abstract: In a pager receiver responsive to a call number signal preassigned thereto, a decoder (25) detects the call number signal to deliver a call indication signal to a loudspeaker (27) and is connected to a connector (36) for use in releasably receiving a controller (35) for detecting a message signal which follows the call number signal. A circuit portion (27, 150) is connected to the detector and the connector to produce the call indication signal simultaneously with detection of the call number signal when the decoder is singly operated. The circuit portion produces the call indication signal after detection of the message signal when the controller is coupled to the decoder through the connector.

Abstract: A paging receiver comprises a P-ROM with a built-in decoder for storage of N kinds of information. The stored contents of the P-ROM are read out in series in response to a clock frequency equal to or greater than N times the clock corresponding to the data speed of a received signal. Substantially simultaneous comparison of N kinds of the read-out data with the received signal is effected to determine whether or not the received signal is a paging signal for the own receiver.

Abstract: A signal detection circuit for a digital radio paging receiver is provided for successfully detecting a desired signal. A demodulated carrier wave, modulated with a code having n bits, is written into an n-stage shift register in response to a clock pulse of frequency f.sub.s. The output stages of the shift register are scanned in response to a scan signal of frequency nf.sub.s in order to provide an output. The output is dependent on the coincidence of the shift register outputs with a predetermined code and is used to enable an address detector circuit which compares a received signal to the desired signal stored in a PROM.

Abstract: In an arc preventing apparatus of a transfer switch connected to an inductive load, the movable contact of the transfer switch is stopped temporarily while it is transferred from one stationary contact to the other by means of a rotary cam. The cam is provided with a high point, a low point and a peripheral portion intermediate the high and low points so that while the actuating lever of the movable contact is engaging the intermediate peripheral portion, the movable contact is held stationary.

Abstract: An electronic detection circuit recognizes a test signal and causes the battery saving feature in a paging receiver to be suspended for a testing period. During testing and receiving periods, battery power is continuously supplied to a receiving circuit. At other times, power is intermittently supplied to the receiving circuit in a prescribed cycle.

Abstract: A radio paging receiver having two power sources, a receiver, a decoder and an oscillator, provides power from the lower of the two voltage sources to the oscillator when the paging receiver is turned off and provides power from the higher of the two voltage sources to the oscillator when the paging receiver is turned on. The oscillator provides higher power pulses to the decoder immediately upon the turn on of the pager thereby providing an immediate normal tone sound from the paging receiver.

Abstract: A digital radio paging communication system has a transmitter and a plurality of receivers. The receivers are energized intermittently to save battery power. The transmitter generates a preamble signal, a synchronization signal, a plurality of calling signals and a stabilization signal, which are arranged into a sequence of signals including two of the preamble signals separated by a measured time interval and at least one batch signal including the synchronization signal and the plurality of calling signals which are divided into a plurality of groups. Each group of calling signals have a stabilization signal at the leading portion thereof followed by a receiver identifying code. A carrier wave is modulated with the sequence of signals and then transmitted. Each of the receivers receives and demodulates the carrier wave. Responsive to the receipt of a first preamble signal, the receiver switches from intermittent to continuous power at an intermediate stand-by level.

Abstract: A radio-paging receiver gives a signal responsive to the receipt of a predetermined sequence of tone signals. The sequence is identified by an identification number stored in and read out of a read-only memory (ROM), which is a high-power consumption circuit. The remainder of the radio-paging receiver is constructed from low-power consumption components. Other than the readout of the ROM, all other of the circuit operations are carried out by the circuits having low-power consumption components. The high-power drain read-only memory is operated only momentarily and then its output is stored in low-power consumption circuits, for future reference. This way, the high-power drain operations are restricted to extremely short periods, with no energy wasted in a waiting time.

Abstract: A tone signal detector for use in paging receivers, transceivers, mobile radio equipment and the like is disclosed. Received tone signals are waveform-converted to generate complementary gating pulses. These gating pulses are used to gate clock pulses to one of two counters, each of which produce a detecting pulse upon counting up to a predetermined number during a predetermined time interval. A detecting pulse from one counter resets the other, and a detecting pulse from either enables a third counter to count clock pulses. This third counter will produce a detecting pulse upon counting up to a predetermined number during a predetermined time interval. The first and second counters enable the tone signal detector to yield detecting pulses without being adversely affected by threshold variations in the waveform converting circuit, while the third counter examines frequency deviation of incoming tone signals.

Abstract: An apparatus first magnitizes a base metal with an alternating flux to cross the welded seam of the base metal and the resulting leakage flux from the welded seam is detected by at least one flux search element to generate an AC signal. The fundamental harmonic component corresponding to the magnetizing signal used for the alternating magnetization is eliminated from the AC signal and the resulting signal voltage is sampled at a fixed period corresponding to the period of the magnetizing signal, thus detecting the center position of the welded seam from the result of the sampling.

Abstract: A motor is energized by a source through first and second transfer switches. Each transfer switch is operated by a switching transistor. The switching transistor for the first transfer switch is driven by a drive signal while the switching transistor for the second transfer switch is driven by the output of a delay circuit responsive to an excessively large current flowing through the motor. A self-holding switch is provided to connect the motor to the source through the second transfer switch.

Abstract: A digital radio pager provides for the reception and detection of (1) a preamble signal for synchronizing the pager to the incoming signal, (2) a calling signal comprised of a unique word associated with the particular individual pager, and (3) a display signal representing the caller identification or other data for display. A switch is provided to enable the pager to selectively produce an audio signal either automatically upon the reception of a properly coded calling signal or, when the user does not want to be disturbed, at any particular time after receiving the calling signal. The switch further provides for selective and repeated visual display of the display signal word upon the request of the user.

Abstract: A digital tone signal detector having N-path filters eliminates the need for a variable-frequency active filter and makes possible the use of integrated circuits in paging receivers, transceivers, mobile radio equipment and so forth. The tone signal detector comprises a clock pulse generator, an N-path filter (where N is an integer equal to or greater than 2), a low-pass filter, a wave shaping circuit, a gate circuit, a counter and detection circuitry. The clock pulse generator generates clock pulses of a predetermined frequency Fc equal to N times the frequency fo of tone signals. The N-path filter samples and selects the tone signal of the frequency fo according to the output of the clock pulse generator. The low-pass filter converts the sampled tone signal including the clock frequency component into a form close to sine wave to eliminate the clock frequency component.

Abstract: A tone signal detecting circuit for use in a paging receiver or the like employs an N-path filter in place of an active filter to facilitate circuit integration. The circuit includes a clock signal generating circuit responsive to a first control signal for selecting and reading out one of plural clock signals of a frequency equal to N (N being an integer equal to or greater than 2) times the frequency of the plural tone signals. The N-path filter has a prescribed rise and fall time and selects and responds to a tone signal in accordance with a clock signal from the clock signal generating circuit. A low-pass filter having prescribed frequency characteristics removes harmonic signals of the tone signals contained in the output of the N-path filter. A tone designating circuit responsive to a second control signal is connected to the low-pass filter and changes its frequency characteristics.

Abstract: When a negative resistance is connected in parallel to a parallel resonance circuit composed of coil and condenser for detecting flaws and other defects of a travelling metal material, the detecting system is capable of improving sensitivity for detecting said flaws and lowering the required degree of amplification of the following amplifier, consequently reducing influence depending upon unbalance of a bridge circuit. At the same time, the simplifying of the power source of said system may be easily realized.