摘要:
An electronic switch keyboard for typewriters or office machines includes a multiple switch at selected key positions to provide two signal inputs to a utilization device. A first capacitor switch is actuated to provide a first signal upon initial key depression and a second contact switch, common to all selected key positions, is actuated to provide a second signal upon further key depression at the selected key positions. A ground plane forms a portion of the contact switch and further serves to reduce parasitic capacitance and to shield the capacitive switches from stray electrical noise occasioned by the contact switch or other electrical inputs. A dielectric material is used to accurately separate the ground plane from the capacitive switch and further serves as a force spreading device for the contact switch. When the keyboard is used in conjunction with a typewriter, the first signal may be used to effect character selection and printing and the second signal to effect repeated printing of the same character. Consistent with prior mechanical typewriter keyboards, three increasing levels of force are required to be overcome as the key is depressed: a pretravel force, a first switch actuation force, and a second switch actuation force.
摘要:
A method and apparatus is provided for facilitating scanning of radio control channels where a plurality of communication systems conjunctively cover the same area. A subscriber unit receives an overhead message train on a control channel which includes a channel count representing the number of control channels of a communication system. Subsequently, the subscriber unit scans a channel count number of control channels to tune to a control channel being used by a communication system having coverage for the subscriber unit. This scanning of control channels starts with a predetermined start control channel which corresponds to the logical number of the control channel in a sequence of control channels which is after the channel count control channel. In addition, an apparatus may be provided to transmit, in the overhead message train, a subscriber unit control message with an address indicating that a communication system is operating within a coverage area.
摘要:
A valve system for use in a subterranean well, the valve having multiple closure devices, or a closure device and a device for protecting the closure device. A valve system includes a valve with a closure assembly. The closure assembly has a closure device and a protective device which alters fluid flow through a flow passage of the valve prior to closure of the closure device to thereby protect the closure device. A safety valve system includes a safety valve with a closure assembly having at least two closure devices arranged in series for controlling flow through a flow passage of the safety valve. Another safety valve system includes a safety valve assembly including multiple safety valves arranged in parallel. One portion of fluid from a fluid source flows through one of the safety valves, while another portion of fluid from the fluid source flows through another safety valve.
摘要:
Mobility is provided for wireless local loop radiotelephone systems by providing the home access network of a subscriber unit with a home access number. Upon registration of the subscriber unit with its home access network, the home access number is transmitted to the subscriber unit for storage there. When the subscriber unit moves to a visited access network and registers there, the subscriber unit transmits the home access number to the visited access network, which uses the home access number to contact the home access network. Since all call originations and terminations by and to the subscriber unit occur via the individual subscriber line appearance at the PSTN, a minimum of special network elements are required for subscriber unit mobility when the home access number is stored at the subscriber unit.
摘要:
The present invention relates to a method and apparatus for enabling RT subscribers (15, 25 and 35), in radio service areas (1, 2 and 3) serviced by a radio telephone control system (11, 21 and 31) (RTCS), to receive calls originally presented to non-servicing RTCSs (11, 21 or 31). In this effort the RTCS (11) currently serving the RT subscriber (15) receives information and a callback number indicating that a call, placed to the RT subscriber (15), is in progress at a remote RTCS (21 or 31). In response, the currently serving RTCS (11) pages the RT subscriber (15). Thereafter, upon receipt of the RT subscriber's page response, the currently serving RTCS (11) calls the callback number so as to connect the RT subscriber (15) to the call in progress.
摘要:
A power supply and control circuit is provided for driving a fluorescent lamp from a low voltage DC power source such as a battery. A DC-to-AC inverter coupled to a switching regulator converts low DC voltage into a higher AC voltage for driving the fluorescent lamp. The lamp is included in a feedback loop which includes a circuit for producing a feedback signal indicative of the magnitude of current conducted by the lamp. The feedback signal is applied to the switching regulator to produce in the lamp a regulated current and, hence, a regulated lamp intensity. The magnitude of the lamp current can be adjusted to enable the intensity of the fluorescent lamp to be smoothly and continuously varied (without "dead-spots" or "pop-on") over a chosen intensity range, including if desired, from substantially full OFF to full ON. A method for driving a fluorescent lamp from a low voltage DC power source is also provided.
摘要:
A boron ion plasma, generated by use of a cathodic arc, is manipulated and delivered to a large flat product such as a silicon wafer with boron ion energies suitable for incorporation of boron atoms into solid state devices as one of the key steps in manufacturing solid state electronics and with uniformity of boron dose over the area suitable for the scale of manufacturing desired.
摘要:
Adjacent cellular systems (101-103) are interconnected to form a network providing telephone coverage to mobiles located throughout their combined coverage areas (111-113). Each networked cellular system (101-103) includes base sites (412, 414, 416) located in cells (402, 404, 406) and a control terminal (420) coupled by data and voice lines to the base sites, a telephone central office (422) and the other cellular systems. Each base site (412, 414, 416) includes a base site controller 950, a scanning receiver 910, signalling transceiver 912 and up to eight voice channel transceivers (901-908). As mobiles move about the networked coverage area (111-113), intrasystem handoffs are provided between cells of the same cellular system, and intersystem handoffs are provided between border cells of adjacent cellular systems. Mobiles are paged throughout the networked coverage area (111-113) in the paging area (121-136) in which the mobile last registered. Registration parameters are updated by the control terminal (420) and base sites (412, 414, 416) and sent to mobiles in the overhead message train. Mobiles automatically register in response to receipt of the overhead message train when moving between paging areas (121-136) according to the flow charts of FIGS. 5 and 6.
摘要:
To control a motor, a pulse width modulated signal from a computer is fed to a capacitor which stores each pulse as a voltage proportional to the width of the pulse, the capacitor being reset to zero by a leading edge reset circuit. The voltage on the capacitor is sampled by a sample/hold circuit the output of which is fed to a converter which converts the voltage signal to a frequency signal exponentially related to the voltage, and hence to the pulse width. The converter then powers a driver which drives the motor. The exponential relationship between the pulses and the signal fed to the motor permits a large variationin the frequency signal based on a small variation in pulse width and hence permits accurate control of the motor.
摘要:
A typewriter is described which has an electronic keyboard utilizing a timed delay to determine whether a depressed key is indicative of the desire to print or display repetitive letters represented by that key. The typewriter is provided with a technique for automatically adjusting the length of the delay such that a slow typist with sluggish finger movement will automatically cause the extension of the delay time and thereby prevent unwanted repetitive characters while a fast, very rhythmic typist will not cause the automatic extension of the delay time and thereby will benefit from a shorter delay time and will have a higher output or productivity as a result thereof.The automatic extension is accomplished by timing the period of time that keylevers are held depressed and when that time approaches but does not exceed the preset automatic delay time, the delay time is then extended a predetermined amount.