Amplifier with long term digitally controlled d c clamping

Abstract

Abstract By way of information and not by way of limitation, a six bit bar code and six clock bars, one clock bar being paired with each bit, are printed on a carton. The bar code positively identifies the article for which the carton is labeled. During a packaging operation the code is scanned and detected and then compared against a reference code identifying the article being placed in the carton. The arrangement of the code bits or code bars relative to the clock bars and to the scanning sequence is such that a complete code is read bit-by-bit into a digital logic circuit only after enabling of the logic circuit by a clock pulse produced in response to the paired clock bar for each bit. This is done by entering the code into a shift register bit-by-bit with register shifting being under the control of the clock bars. If the code read is not true to the reference code, a reject indication is provided or the carton bearing the incorrect code is automatically rejected from the packaging line. Code and clock pulse signals are fed to the register via specially constructed amplifiers whose output levels are clamped by respective control circuits each of which comprise an oscillator, a threshold detector, a counter, and a digital-to-analog convertor. The analog output from the convertor reduces the input signal when the amplifier output goes above the threshold of the detector.

Inventors

• 👤 K Law
• 👤 G Brown

Bibliographic Details