Circular track coded pattern reader

Claim 2

A label reading system for reading a circular coded label with a scan path within a predetermined alignment tolerance range between said circular label and scan path comprising: means for scanning said label and producing label code signals representing the encoded information; a clock pulse generator for generating clock pulses; a clock control circuit for controlling the frequency of said clock pulse generator; and a variable synchronizing circuit responsive to said label code signals and to said clock pulses, for producing a phase signal representative of the difference in phase between said clock pulses and said label code signals, said clock control circuit being responsive to said phase signal to vary the frequency of said clock pulse generator to synchronize said clock pulses with said label code signals as said label code signals vary within said tolerance range.

Claim 3

The system of claim 1 in which said clock pulse generator includes means fo selecting every other clock pulse to form a digital clock pulse signal and the alternate clock pulse to form a label clock pulse signal, and said synchronizing unit includes a first gate responsive to said label code signal and said digit clock pulse signal and a second gate responsive to said label code signal and said label clock pulse signal.

Claim 4

The system of claim 2 in which said labels include a number of sectors of coded information and said digit clock pulse signals align approximately withthe transitions between sectors and said label clock pulse signals align approximately with the centers of said sectors.

Claim 5

The system of claim 1 further including a pulse rate detector responsive to said clock pulse generator for determining the difference between the frequency of said clock pulse and a predetermined reference level and providing a signal reprEsentative thereof to said clock control circuit for establishing a stabilized frequency for said clock pulse generator during non-label reading periods.

Claim 6

The system of claim 1 in which said synchronizing circuit includes means responsive to said phase signal, for averaging the effect of differences between the frequency of said label code signals and clock pulse on said clock control circuit and clock pulse generator to permit said clock pulse generator to hold its frequency during occasional absences of a label code signal and to accommodate minor variations in width of said sectors.

Claim 7

The system of claim 1 in which a said label include a plurality of sectors having either one of two contrasting states, and further including a no-label detection circuit for determining that a label reading cycle has been ended including gate means responsive to said clock pulses for passing label code signals of a first of said states, counter means responsive to said gate means for counting the number of contiguous label code signals in said first state, means for resetting said counter means upon each occurrence of a label code signal of the second state, and means, responsive to a predetermined count of label code signals in said first state in excess of the number of such label code signals in said first state normally occurring in the code used on the label, for indicating that a label is no longer being read.

Claim 8

A label reading system for reading a circular coded label with a scan path within a predetermined alignment tolerance range between said circular label and scan path comprising: means for scanning said label and producing label code signals representing the encoded information; a clock pulse generator for generating clock pulses; a clock control circuit for controlling the frequency of said clock pulse generator; a no-label detection circuit for determining that a label reading cycle has been ended including gate means responsive to said clock pulses for passing label code signals of a first of said states, counter means responsive to said gate means for counting the number of contiguous label code signals in said first state, means for resetting said counter means upon each occurrence of a label code signal of the second state, and means, responsive to a predetermined count of label code signals in said first state in excess of the number of such label code signals in said first state normally occurring in the code used on the label, for indicating that a label is no longer being read; means responsive to said means for scanning, for accumulating label code signals representative of a group of sectors, means for determining whether such a group has a number of sectors in the first state equal to the number of sectors in the second state, and means for determining that there are no more than two sectors of the same state contiguous to one another; said label including a plurality of sectors having either one of two contrasting states and a start grouo and a plurality of data groups, each including an equal number of sectors having either one of two states.

Claim 9

A label reading system for reading a circular coded label with a scan path within a predetermined alignment tolerance range between said circular label and scan path comprising: means for scanning said label and producing label code signals representing the encoded information; a clock pulse generator for generating clock pulses; a clock control circuit for controlling the frequency of said clock pulse generator; a no-label detection circuit for determining that a label reading cycle has been ended including gate means responsive to said clock pulses for passing label code signals of a first of said states, counter means responsive to said gate means for counting the number of contiguous label code signals in said first state, means for resetting said counter means upon each occurrence of a label code signal of the second state, and means, responsive to a predetermined count of label code signals in said first state in excess of the number of such label code signals in said first state normally occurring in the code used on the label, for indicating that a label is no longer being read; means responsive to said means for scanning, for accumulating label code signals representative of a group of sectors, means for determining whether such a group has a number of sectors in the first state equal to the number of sectors in the second state, and means for determining that there are no more than two sectors of the same state contiguous to one another; said label including a plurality of sectors having either one of two contrasting states and a start grouo and a plurality of data groups, each including an equal number of sectors having either one of two states.

Claim 10

The system of claim 7 further including means for storing label code signals representative of groups of sectors, and means, responsive to said no-label detection circuit, for preventing reading out of said label code signals from said means for storing in the absence of an indication from said no-label detection circuit that said label code signals were accumulated following a no-label detection period.

Claim 11

A label reading system for reading a circular coded label with a scan path within a predetermined alignment tolerance range between said circular label and scan path comprising: means for scanning said label and producing label code signals representing the encoded information; a clock pulse generator for generating clock pulses; a clock control circuit for controlling the frequency of said clock pulse generator; said label including a series of groupS of sectors including a plurality of data groups and a parity group, each group including an equal number of sectors representing a number; said system further including a parity checking circuit including adder means, means for storing a number, means for placing a first number in said means for storing, means for presenting a series of numbers, corresponding to said series of groups, one at a time to one input of said adder, means for supplying at the other input of said adder the complement of the number stored in said means for storing, means for loading into said means for storing the sum produced by said adder, and means following the processing of said series of numbers corresponding to said series of groups including a plurality of data groups and a parity group for indicating whether parity is achieved.

Claim 12

A label reading system for reading a circular coded label with a scan path within a predetermined alignment tolerance range between said circular label and scan path comprising: means for scanning said label and producing label code signals representing the encoded information; a clock pulse generator for generating clock pulses; a clock control circuit for controlling the frequency of said clock pulse generator; said label including a series of groupS of sectors including a plurality of data groups and a parity group, each group including an equal number of sectors representing a number; said system further including a parity checking circuit including adder means, means for storing a number, means for placing a first number in said means for storing, means for presenting a series of numbers, corresponding to said series of groups, one at a time to one input of said adder, means for supplying at the other input of said adder the complement of the number stored in said means for storing, means for loading into said means for storing the sum produced by said adder, and means following the processing of said series of numbers corresponding to said series of groups including a plurality of data groups and a parity group for indicating whether parity is achieved.

Claim 13

The system of claim 9 in which said means for placing a first number in said means for storing includes a preselection circuit for placing a base number in said means for storing prior to processing said series of numbers.