摘要:
A process for assuring that the individual computational elements of a fault-tolerant computer system have the same view of the external world when applied in applications where input data representations of the same quantity may have slight variations without being incorrect. The process transmits data between each of the computational elements through circuitry utilizing transmitters and receivers, and provides a check as to the accuracy of each such transmission, resulting in each computational element either having the same plurality of data as each other computational element, or a representation that a transmission was faulty.
摘要:
An optical scanning system operates asynchronously by electro-optically detecting movement of a scanning unit directly from the data being scanned. A first embodiment of the system includes two sets of optical sensors in a handheld unit. One set extends transversely of a scanning direction for detecting the optical pattern, and a second set is approximately aligned with the scanning direction for detecting relative movement between the pattern and the scanning unit. Relative movement is detected by detecting a pattern in a first subset of the second set of sensors and then sensing a shift of the detected pattern to a second subset of the second set of sensors. In response to detecting a unit movement, the optical states of the first set of sensor elements are polled to record a portion of the pattern along the line. This response is preferably triggered indirectly by calculating an average time interval between relative movements and periodically polling the first set of sensors at a rate set by this average interval. Upon detecting a uniform optical state of the second set of sensors, such as when scanning across a blank region in the pattern, sensing of the optical state of the first sensors continues at periodic intervals so long as the uniform state continues to be detected. The optical information is thus obtained in a succession of steps, and is assembled by the host computer. A second embodiment of the system differs from the first embodiment in that the former uses a rectangular array of imaging elements arranged in rows and columns and calculates an estimate of the instantaneous rate of relative movement. Each of the rows of imaging elements is aligned generally parallel to the scanning direction and changes optical states in a manner analogous to that of the line of second imaging elements described above. The second embodiment promotes increased accuracy during collection of optical information for situations in which the scanning direction is misaligned from the optical information and the scanning velocity is nonuniform.
摘要:
The disclosure describes an improved analog-to-digital converter which enables the use of a reference voltage having the same polarity as the input analog voltage being converted. The converter employs an operational amplifier having a capacitive feedback network, an inverting input, and a non-inverting input. The inverting input is periodically disconnected so that the output of the operational amplifier slews to a new value without substantially changing the voltage across the capacitive feedback network.
摘要:
A document reader for reading manually fed edge coded documents, comprising a first component including a side wall, a second component orthogonally positioned with respect to the first component and having a second sidewall, the first and second sidewalls positioned adjacent one another so as to form a document receiving slot therebetween, the first sidewall containing an opening, a drive means, the drive means positioned within the first component and adapted to project through the first sidewall opening and substantially across the slot, the second sidewall including an opening, reading means contained within the second component, the reading means including a light source, means for directing light from the source through the second wall opening to the document, means responsive to light reflected from the document for converting the reflected light to digital data, control means coupled to the drive means, sensing means positioned proximate to the slot for sensing the precise location of the document, the sensing means coupled to the control means and responsive to the sensed document for controlling the drive of the document past the first and second openings.
摘要:
An optical scanning system operates asynchronously by electro-optically detecting movement of a scanning unit directly from the data being scanned. A first embodiment of the system includes two sets of optical sensors in a hand-held unit. One set extends transversely of a scanning direction for detecting the optical pattern, and a second set is approximately aligned with the scanning direction for detecting relative movement between the pattern and the scanning unit. Relative movement is detected by detecting a pattern in a first subset of the second set of sensors and then sensing a shift of the detected pattern to a second subset of the second set of sensors. In response to detecting a unit movement, the optical states of the first set of sensor elements are polled to record a portion of the pattern along the line. This response is preferably triggered indirectly by calculating an average time interval between relative movements and periodically polling the first set of sensors at a rate set by this average interval. Upon detecting a uniform optical state of the second set of sensors, such as when scanning across a blank region in the pattern, sensing of the optical state of the first sensors continues at periodic intervals so long as the uniform state continues to be detected. The optical information is thus obtained in a succession of steps, and is assembled by the host computer. A second embodiment of the system differs from the first embodiment in that the former uses a rectangular array of imaging elements arranged in rows and columns and calculates an estimate of the instantaneous rate of relative movement. Each of the rows of imaging elements is aligned generally parallel to the scanning direction and changes optical states in a manner analogous to that of the line of second imaging elements described above. The second embodiment promotes increased accuracy during collection of optical information for situations in which the scanning direction is misaligned from the optical information and the scanning velocity is nonuniform.
摘要:
An analog selector circuit for providing an analog output signal of a value approximate to the median value of the analog input signals, having a plurality of comparator means equal to the number of analog input signals, each comparator means being connected to receive one of the input signals and comparing the received signal with the analog output signal of the selector circuit, a plurality of electronic control valves connected to receive the output signals from the plurality of comparator means, the valves being connected such that a number of said valves equal in number to the majority of analog input signals are connected in series to form a series combination and there are a sufficient number of such series combinations to receive all combinations of the majority of voltage output signals, and each series combination connected to receive a voltage potential input signal and providing the output signals of the series combinations to a common terminal to form the analog output signal; and a resistive network connected between the common terminal and a reference potential.