Abstract: In a static optical bar code reader, a stationary bar code is disposed in operative relationship to a light sensitive charge coupled device. The photosites of the charge coupled device convert light from the contrasting segments of the bar code to an analog voltage. The analog output of the charge coupled device is applied to a circuit which converts it to a digital signal. The digital signal is transmitted to a suitably programmed microprocessor which preferably decodes the digital signal and recovers the information included in the bar code. The output of the microprocessor may be applied to a display, a host computer or some other utilization device.

Abstract: An ink jet printer control circuit is disclosed in which provision is made for production of drop clock signal pulses for application to the electromechanical drop stimulation transducer of the printer. Print enable pulses are provided by a state controller means to the charge electrode driver of the printer so as to permit selective charging of drops produced by the jet drop stream. An edge detector means is responsive to the leading edge of each pulse in the drop clock signal pulse train to provide an edge detection pulse. Additionally, an encoder arrangement provides a train of synchronization pulses, each such pulse signifying an increment of movement of the print receiving medium. The state controller responds to the edge detection pulses and to the synchronization pulses and provides a print enable pulse upon receipt of an edge detection pulse next following receipt of a synchronization pulse.

Abstract: In biphase operations where logic 1's are represented by a logic 0-1 code in a data stream which controls bar code printing, and logic 0's are represented by a logic 1-0 code, the invention involves altering to a logic 0-0 code in the stream each logic 1-0 code which follows a logic 0-1 code.In a more specific aspect, binary information signals are encoded for detection by a reading system effective within a bandwidth of bar densities. Such encoding is effected by sensing each bit time period of the binary information signal, and representing a logic one level occurring within a bit time period by inserting a logic one level in a trailing half of a corresponding bit time period of an encoded signal. If a logic zero level is sensed in a bit time period of the binary information signal after the detection of a logic one level in an immediately preceding bit time period, logic 0's are inserted in the leading and trailing halves of a corresponding bit time period of the encoded signal.

Abstract: Bar-code data is read in the presence of noise. An analog output signal from a bar-code sensor has amplitude variations dependent upon the presence and absence of bars as well as upon differences in backgrounds upon which the bars are printed. The output signal is normalized to minimize variations therein, and the normalized signal in turn is converted to a digital signal at a sample interval small compared to the period of the known waveform. An expected response to each bar is of a known waveform. A digital reference set is stored which represents products formed by multiplying each quantization level of the digital signal by each sample of the known waveform taken at the sample interval. For each sample interval along the output signal, members of the reference set are selected dependent upon the sample interval of the known waveform and the corresponding amplitude of the digital signal, and summed to form one point of a correlation output function.

Abstract: Video signals generated by reading bar coded documents are transformed into pulses uniformly truncated in amplitude and having transitions only at points corresponding to change in sign of the slope of the adjusted video signals. The pulses are utilized to control the state of an output device depending upon whether the integral of any of the truncated pulses exceeds a reference level.