Photo-electric reader and frequency tone code converter

Claim 2

An N-channel code reader comprising: N individual channel reading circuits corresponding respectively to said N channels; said reading circuits including respective bit sensing means producing respective outputs representing the presence or absence of bits in the corresponding channels, respective binary comparators each having first and second comparison inputs, said first comparison inputs being responsive to the respective outputs of the corresponding channel bit sensing means, and respective output means responsive to a selected binary value of the respective comparator outputs; a common summer responsive to the outputs of all N individual channel bit sensing means; and means conveying a signal, proportional to the output of said summer, to said second comparison inputs of all N individual channel comparators; whereby each individual channel comparator compares its respective individual channel bit sensing means output signal with a variable reference level proportional to the average of the bit sensing means outputs of all N channels.

Claim 3

A code reader as in claim 1 for a written spot code; wherein each of said bit sensing means is a photo-electric detector.

Claim 4

A code reader as in claim 2 further comprising: a gas discharge lamp for illuminating a spot-coded data record; and means for connecting said lamp across an alternating current energizing source.

Claim 5

A code reader as in claim 1 wherein: said bit sensing means comprise respective photoconductive cells; respective current-to-voltage converter circuits are responsive to respective ones of said photoconductive cells; and said binary comparators comprise respective operational amplifiers arranged to operate in a switching voltage comparator mode, with their respective first comparison inputs responsive to the outputs of respective current-to-voltage converters.

Claim 6

A code reader as in claim 4 wherein: said summer comprises an operational amplifier arranged to operate in the summing mode, and has a plurality of inputs connected to the respective outputs of said current-to-voltage converters; and said signal conveying means is arranged to convey the output of said summing operational amplifier to the second comparison inputs of all said switching comparator operational amplifiers.

Claim 7

A code reader as in claim 5 wherein said signal conveying means is an operational amplifier connected to operate in a dividing mode, whereby to divide the output of said summing operational amplifier by a predetermined quantity to develop a signal proportional to the average of said individual channel bit sensing outputs.

Claim 8

A code reader as in claim 6 wherein said output means comprise respective binary switching circuits responsive to the outputs of respective switching comparator operational amplifiers.

Claim 9

A multi-tone code converter comprising: M reading channels corresponding respectively to M bits of a first code group designating a first frequency tone; N reading channels corresponding respectively to N bits of a second code group designating a second frequency tone; said channels including respective bit sensing means producing respective outputs representing the presence or absence of bits in the corresponding channels, respective binary comparators each having first and second comparison inputs, each of said first comparison inputs being responsive to the respective outputs of the corresponding channel bit sensing means, and respective output means responsive to a selected binary value of the respective outputs of the corresponding channel comparators; a first summer responsive to the outputs of all M individual channel sensing means of said first code group; a second summer responsive to thE outputs of all N individual channel sensing means of said second code group; means for conveying a signal, proportional to the output of said first summer, to said second comparison inputs of all M individual channel comparators of said first code groups; means for conveying a signal, proportional to the output of said second summer, to said second comparison inputs of all N individual channel comparators of said second code group; whereby each channel comparator compares its respective channel bit sensing means output signal with a variable reference level proportional to the average of the bit sensing means outputs of all channels of its respective code group; and a multi-tone encoder responsive to one of said output means of said first code group to produce a first frequency tone, and responsive to one of said output means of said second code group to produce a second frequency tone.

Claim 10

A multi-tone code converter comprising: M reading channels corresponding respectively to M bits of a first code group designating a first frequency tone; N reading channels corresponding respectively to N bits of a second code group designating a second frequency tone; said channels including respective bit sensing means producing respective outputs representing the presence or absence of bits in the corresponding channels, respective binary comparators each having first and second comparison inputs, each of said first comparison inputs being responsive to the respective outputs of the corresponding channel bit sensing means, and respective output means responsive to a selected binary value of the respective outputs of the corresponding channel comparators; a first summer responsive to the outputs of all M individual channel sensing means of said first code group; a second summer responsive to thE outputs of all N individual channel sensing means of said second code group; means for conveying a signal, proportional to the output of said first summer, to said second comparison inputs of all M individual channel comparators of said first code groups; means for conveying a signal, proportional to the output of said second summer, to said second comparison inputs of all N individual channel comparators of said second code group; whereby each channel comparator compares its respective channel bit sensing means output signal with a variable reference level proportional to the average of the bit sensing means outputs of all channels of its respective code group; and a multi-tone encoder responsive to one of said output means of said first code group to produce a first frequency tone, and responsive to one of said output means of said second code group to produce a second frequency tone.

Claim 11

A combination luminescent spot reader and multi-tone frequency code generator comprising: means for scanning a document which is printed with a luminescent spot code wherein each coded character includes at least two code groups, each of said code groups contains a plurality of channels, and one of the channels in each code group of each character is imprinted with a luminescent bit; a radiation source for activating said luminescent bits during scanning; individual photo-electric bit sensing means for each channel of each code group, adapted to detect luminescent radiation from activated bits; and individual frequency tone generating means for each channel of each code group, operable in response to their respective channel bit sensing means whereby to generate, for each coded character, a first frequency tone representative of which channel position has a luminescent bit in a first one of said code groups, and a second frequency tone representative of which channel position has a luminescent bit in a second one of said code groups, on said document, and for jointly transmitting said first and second frequency tones as a multi-tone frequency coded representation of said character.

Claim 12

A combination luminescent spot reader and multi-tone frequency code generator comprising: means for scanning a document which is printed with a luminescent spot code wherein each coded character includes at least two code groups, each of said code groups contains a plurality of channels, and one of the channels in each code group of each character is imprinted with a luminescent bit; a radiation source for activating said luminescent bits during scanning; individual photo-electric bit sensing means for each channel of each code group, adapted to detect luminescent radiation from activated bits; and individual frequency tone generating means for each channel of each code group, operable in response to their respective channel bit sensing means whereby to generate, for each coded character, a first frequency tone representative of which channel position has a luminescent bit in a first one of said code groups, and a second frequency tone representative of which channel position has a luminescent bit in a second one of said code groups, on said document, and for jointly transmitting said first and second frequency tones as a multi-tone frequency coded representation of said character.