Field detection logic

Claim 2

In a code reading system in which scanning means scans a coded medium along a given path that includes a plurality of contiguous detectable indicia arranged in a coded format, each indicia having one of at least three detectably different characteristics, said code being defined by transitions from an indicium of one characteristic to an indicium of a different characteristic, the first detected and last detected indicium having the same characteristic and being detected for a longer amount of time than the remaining indicia, said scanning means providing one of a first, a second, or a third indicium signal whenever said scanning means scans an indicium having a respective one of a first, a second or a third detectably different characteristic, logic for determining when said plurality of indicia are being scanned comprising: means responsive to said first, second and third indicium signals to determine the amount of time each of said indicia is detected, said means including a first counter means and a second counter means, said first counter means being reset to a zero count upon the occurrence oF said first indicium signal and said second counter means being reset to zero upon the occurrence of either said second indicium signal or said third indicium signal, said first and second counter means, after being reset to zero count, counting as long as the indicium signal causing them to be reset is provided, the counts of said first and second counter means being operated upon after the signal provided by said scanning means changes, said counter means thereafter counting; means responsive to the count of said first counter means for providing a first signal whenever the amount of time for detecting a certain indicium is a certain amount less than the amount of time for detecting the immediately preceding indicium; and means responsive to the count of said second counter means for providing a second signal whenever the amount of time for detecting a second certain indicium is a certain amount greater than the amount of time for detecting the immediately preceding indicium.

Claim 3

This invention according to claim 1 wherein said first signal is provided in response to the count in said first counter when the next following scanning means indicium signal change occurs, and said second signal is provided when the count of said second counter reaches a given value.

Claim 4

The invention according to claim 1 wherein the count in said first counter is operated upon by dividing it by a given amount and inverting it; and wherein said first signal is provided at the point in time said next following scanning means indicium signal change occurs as long as said counter is not saturated.

Claim 5

The invention according to claim 3 wherein said count in said first counter is divided by four.

Claim 6

The invention according to claim 1 wherein the count in said second counter is operated upon by being inverted; wherein said second counter thereafter counts up at a slower rate than prior to said count being operated upon; and wherein said second signal is provided when said second counter becomes saturated.

Claim 7

The invention according to claim 5 wherein said slower rate is one fourth of the prior counting rate.

Claim 8

In combination: an encoded medium on which is positioned a series of contiguous color bars of first, second and third colors, said medium having a background area of said first color, there being a path on said medium traversing said series of bars and a portion of said background area on each side of said series of bars, the background area on each side of said series of bars traversed by said path being wider than the width of said bars along said path; detecting means for being scanned along said path and for providing one of a first, second, or a third signal whenever respective first, second or third colors are scanned; first counter means responsive to said first, second, and third signals capable of counting between first and second values, said first counter means including means for resetting said first counter means to said first value upon the occurrence of said first signal, said first counter means thereafter counting towards said second value, said first counter means further including means for dividing the then existing count thereof by a given value and complementing said divided value at the time one of said second or third signals occur following the occurrence of said first signal, said first counter means thereafter counting towards said second value; first decoding means for providing a beginning signal after said one of said second or third signals no longer is provided in the event said first counter means has not counted past a third value which is between said first and second values; second counter means responsive to said first, second and third signals capable of counting between fourth and fifth values, said second counter means including means for resetting said second counter means to said fourth value upon the occurrence of said second or said third signals said second couNter means thereafter counting towards said fifth value at a given rate, said resetting means further resetting the count of said second counter means to the complement of the then-existing count thereof upon the occurrence of said first signal, said second counter means thereafter counting towards said fifth value at a second rate, which is less than said given rate; and second decoding means for providing an ending signal when the count of said second counter reaches said fifth value.

Claim 9

In combination: an encoded medium on which is positioned a series of contiguous color bars of first, second and third colors, said medium having a background area of said first color, there being a path on said medium traversing said series of bars and a portion of said background area on each side of said series of bars, the background area on each side of said series of bars traversed by said path being wider than the width of said bars along said path; detecting means for being scanned along said path and for providing one of a first, second, or a third signal whenever respective first, second or third colors are scanned; first counter means responsive to said first, second, and third signals capable of counting between first and second values, said first counter means including means for resetting said first counter means to said first value upon the occurrence of said first signal, said first counter means thereafter counting towards said second value, said first counter means further including means for dividing the then existing count thereof by a given value and complementing said divided value at the time one of said second or third signals occur following the occurrence of said first signal, said first counter means thereafter counting towards said second value; first decoding means for providing a beginning signal after said one of said second or third signals no longer is provided in the event said first counter means has not counted past a third value which is between said first and second values; second counter means responsive to said first, second and third signals capable of counting between fourth and fifth values, said second counter means including means for resetting said second counter means to said fourth value upon the occurrence of said second or said third signals said second couNter means thereafter counting towards said fifth value at a given rate, said resetting means further resetting the count of said second counter means to the complement of the then-existing count thereof upon the occurrence of said first signal, said second counter means thereafter counting towards said fifth value at a second rate, which is less than said given rate; and second decoding means for providing an ending signal when the count of said second counter reaches said fifth value.

Claim 10

The invention according to claim 7; wherein said first value is zero; wherein said second value is two to the nth power; and wherein said third value is two to the n minus two power.

Claim 11

The invention according to claim 8; wherein said given value is four; and wherein said detecting means detects said background area on each side of said bars for at least four times as long as any bar is detected.

Claim 12

The invention according to claim 7: wherein said fourth value is zero; wherein said fifth value is two to the nth power; wherein said second rate is one fourth of said given rate; and wherein said detecting means detects said background area on each side of said bars for at least four times as long as any bar is detected.

Claim 13

The invention according to claim 10: wherein said first value is zero; wherein said second value is two to the n plus one power; wherein said third value is two to the n minus one power; and wherein said given value is four.