US3849632A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reading apparatus for optical bar codes
Assignee: Pitney Bowes Inc
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Filing: 1973-05-04
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Granted: 1974-11-19
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Expires: 1993-05-04
Abstract
Abstract Reading apparatus for optical, linear bar codes having variable width encoded bar and space code elements includes a photodetector for developing a video signal which is fed to an analog to digital converter. This converter, which consists of a dual level clamping circuit and a triggering circuit, operates on each video signal transition of a predetermined magnitude, corresponding to scanning across the edges of the code elements, to develop a succession of alternating logic signal pulses and pulse intervals of widths respectively proportional to the widths of the successive code elements; the logic signal pulses being supplied to processing logic circuitry for decoding the bar code.
Inventors
- 👤 A Eckert
- 👤 J Steinmetz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:53
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/01; G06K7/016; G06K7/0166
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
359 words
An apparatus for extracting width information from a linear bar code having variable width encoded elements and for impressing said information upon a width-modulated two-state signal, said apparatus comprising: scanning means for scanning said linear bar code along a path which traverses said bar code and for generating a video signal whose potential varies in accordance with the varying characteristics of the elements along the path; a capacitive element having a first terminal to which said video signal is applied and also having a second terminal at which a clamped signal appears; means for establishing a first clamping potential level at a first node and also a second clamping potential level at a second node which second clamping potential level is below the potential of said first clamping potential level, said means for establishing including means for maintaining a predetermined non-zero fixed-potential magnitude between said nodes; first clamping means connecting to said capacitive element second terminal for preventing the potential of said capacitive element second terminal from rising above said first clamping potential level; second clamping means connected to said capacitive element second terminal for preventing the potential of said capacitive element second terminal from falling below said second clamping potential level; and a triggering circuit having an input connecting to said clamped signal, having an output at which the width-modulated two-state signal appears, and having the following trigger characteristic when the potential of said capacitive element second terminal swings positive from a level at or near said second clamping potential level, said two-state signal remains in a first state until the potential of said capacitive element second terminal swings more than half-way from said second clamping potential level towards said first clamping potential level, and then said two-state signal enters its second state, and when the potential of said capacitive element second terminal swings negative from a level at or near said first clamping potential level, said two-state signal remains in its second state until the potential of said capacitive element second terminal swings more than half-way from said first clamping potential level towards said second clamping potential level, and then said two-state signal enters its first state.
Claim 2
Independent Claim
359 words
An apparatus for extracting width information from a linear bar code having variable width encoded elements and for impressing said information upon a width-modulated two-state signal, said apparatus comprising: scanning means for scanning said linear bar code along a path which traverses said bar code and for generating a video signal whose potential varies in accordance with the varying characteristics of the elements along the path; a capacitive element having a first terminal to which said video signal is applied and also having a second terminal at which a clamped signal appears; means for establishing a first clamping potential level at a first node and also a second clamping potential level at a second node which second clamping potential level is below the potential of said first clamping potential level, said means for establishing including means for maintaining a predetermined non-zero fixed-potential magnitude between said nodes; first clamping means connecting to said capacitive element second terminal for preventing the potential of said capacitive element second terminal from rising above said first clamping potential level; second clamping means connected to said capacitive element second terminal for preventing the potential of said capacitive element second terminal from falling below said second clamping potential level; and a triggering circuit having an input connecting to said clamped signal, having an output at which the width-modulated two-state signal appears, and having the following trigger characteristic when the potential of said capacitive element second terminal swings positive from a level at or near said second clamping potential level, said two-state signal remains in a first state until the potential of said capacitive element second terminal swings more than half-way from said second clamping potential level towards said first clamping potential level, and then said two-state signal enters its second state, and when the potential of said capacitive element second terminal swings negative from a level at or near said first clamping potential level, said two-state signal remains in its second state until the potential of said capacitive element second terminal swings more than half-way from said first clamping potential level towards said second clamping potential level, and then said two-state signal enters its first state.
Claim 3
Independent Claim
381 words
An apparatus for extracting width information from a linear bar code having variable width encoded elements and for impressing said information upon a width-modulated two-state signal, said apparatus comprising: scanning means for scanning said linear bar code along a path which traverses said bar code and for generating a video signal whose potential varies in accordance with the varying characteristics of the elements along the path; a capacitive element having a first terminal to which said video signal is applied and also having a second terminal at which a clamped signal appears; first clamping means connecting to said capacitive element second terminal for preventing the potential of said capacitive element second terminal from rising above a first clamping potential level; second clamping means connected to said capacitive element second terminal for preventing the potential of said capacitive element second terminal from falling below a second clamping potential that is below the level of said first clamping potential; and a triggering circuit having an input connecting to said clamped signal, having an output at which the width-modulated two-state signal appears, which triggering circuit comprises an amplifier having a signal input connecting to said clamped signal, having an output at which the width-modulated two-state signal appears, and having a non-inverting input, said triggering circuit also including resistive elements connecting said non-inverting input to said output and also to a fixed-reference potential, wherein the ohmic values of the resistive elements and the voltage of the reference potential are selected to give the following trigger characteristic when the potential of said capacitive element second terminal swings positive from a level at or near said second clamping potential level, said two-state signal remains in a first state until the potential of said capacitive element second terminal swings more than half-way from said second clamping potential level towards said first clamping potential level, and then said two-state signal enters its second state, and when the potential of said capacitive element second terminal swings negative from a level at or near said first clamping potential level, said two-state signal remains in its second state until the potential of said capacitive element second terminal swings more than half-way from said first clamping potential level towards said second clamping potential level, and then said two-state signal enters its first state.
Claim 4
Independent Claim
381 words
An apparatus for extracting width information from a linear bar code having variable width encoded elements and for impressing said information upon a width-modulated two-state signal, said apparatus comprising: scanning means for scanning said linear bar code along a path which traverses said bar code and for generating a video signal whose potential varies in accordance with the varying characteristics of the elements along the path; a capacitive element having a first terminal to which said video signal is applied and also having a second terminal at which a clamped signal appears; first clamping means connecting to said capacitive element second terminal for preventing the potential of said capacitive element second terminal from rising above a first clamping potential level; second clamping means connected to said capacitive element second terminal for preventing the potential of said capacitive element second terminal from falling below a second clamping potential that is below the level of said first clamping potential; and a triggering circuit having an input connecting to said clamped signal, having an output at which the width-modulated two-state signal appears, which triggering circuit comprises an amplifier having a signal input connecting to said clamped signal, having an output at which the width-modulated two-state signal appears, and having a non-inverting input, said triggering circuit also including resistive elements connecting said non-inverting input to said output and also to a fixed-reference potential, wherein the ohmic values of the resistive elements and the voltage of the reference potential are selected to give the following trigger characteristic when the potential of said capacitive element second terminal swings positive from a level at or near said second clamping potential level, said two-state signal remains in a first state until the potential of said capacitive element second terminal swings more than half-way from said second clamping potential level towards said first clamping potential level, and then said two-state signal enters its second state, and when the potential of said capacitive element second terminal swings negative from a level at or near said first clamping potential level, said two-state signal remains in its second state until the potential of said capacitive element second terminal swings more than half-way from said first clamping potential level towards said second clamping potential level, and then said two-state signal enters its first state.
Claim 5
Independent Claim
387 words
An apparatus for extracting width information from a linear bar code having variable width-coded elements and for impressing said information upon a width-modulated two-state signal, said apparatus comprising: scanning means for scanning said linear bar code along a path which traverses said bar code and for generating a video signal whose potential varies in accordance with the varying characteristics of the elements along the path; a capacitive element having a first terminal to which said video signal is applied and also having a second terminal at which a clamped signal appears; first clamping means connecting to said capacitive element second terminal for preventing the potential of said capacitive element second terminal from rising above a first clamping potential level, said first clamping means including a first diode having an anode terminal connecting to said capacitive element second terminal and having a cathode terminal connecting to at least one other element of said first clamping means; second clamping means connecting to said capacitive element second terminal for preventing the potential of said capacitive element second terminal from falling below a second clamping potential level that is below the level of said first clamping potential level, said second clamping means including a second diode having a cathode terminal connecting to said capacitive element second terminal and having an anode terminal connecting to at least one other element of said second clamping means; and a triggering circuit having an input connecting to said clamped signal, having an output at which the width-modulated two-state signal appears, and having the following trigger characteristic when the potential of said capacitive element second terminal swings positive from a level at or near said second clamping potential level, said two-state signal remains in a first state until the potential of said capacitive element second terminal swings more than half-way from said second clamping potential level towards said first clamping potential level, and then said two-state signal enters its second state, and when the potential of said capacitive element second terminal swings negative from a level at or near said first clamping potential level, said two-state signal remains in its second state until the potential of said capacitive element second terminal swings more than half-way from said first clamping potential level towards said second clamping potential level, and then said two-state signal enters its first state.
Claim 6
Independent Claim
387 words
An apparatus for extracting width information from a linear bar code having variable width-coded elements and for impressing said information upon a width-modulated two-state signal, said apparatus comprising: scanning means for scanning said linear bar code along a path which traverses said bar code and for generating a video signal whose potential varies in accordance with the varying characteristics of the elements along the path; a capacitive element having a first terminal to which said video signal is applied and also having a second terminal at which a clamped signal appears; first clamping means connecting to said capacitive element second terminal for preventing the potential of said capacitive element second terminal from rising above a first clamping potential level, said first clamping means including a first diode having an anode terminal connecting to said capacitive element second terminal and having a cathode terminal connecting to at least one other element of said first clamping means; second clamping means connecting to said capacitive element second terminal for preventing the potential of said capacitive element second terminal from falling below a second clamping potential level that is below the level of said first clamping potential level, said second clamping means including a second diode having a cathode terminal connecting to said capacitive element second terminal and having an anode terminal connecting to at least one other element of said second clamping means; and a triggering circuit having an input connecting to said clamped signal, having an output at which the width-modulated two-state signal appears, and having the following trigger characteristic when the potential of said capacitive element second terminal swings positive from a level at or near said second clamping potential level, said two-state signal remains in a first state until the potential of said capacitive element second terminal swings more than half-way from said second clamping potential level towards said first clamping potential level, and then said two-state signal enters its second state, and when the potential of said capacitive element second terminal swings negative from a level at or near said first clamping potential level, said two-state signal remains in its second state until the potential of said capacitive element second terminal swings more than half-way from said first clamping potential level towards said second clamping potential level, and then said two-state signal enters its first state.
Claim 7
Dependent Claim
46 words
An apparatus in accordance with claim 3 which further includes a resistive element connecting said capacitive element second terminal to a source of biasing potential and thus arranged to bias said two-state signal into a predetermined state at times when no meaningful scanning is in progress.
Claim 8
Dependent Claim
160 words
An apparatus in accordance with claim 3 which includes a linear, signal-inverting amplifier having an input connecting to said capacitive element second terminal, having an output connected to the input of said trigger circuit, and Pg,25 arranged to linearly amplify said clamped signal; which also includes first and second constant voltage elements each having first and second terminals and each including means for maintaining a relatively constant potential difference between the constant voltage element terminals; wherein the first clamping means, in addition to said first diode, comprises said first constant voltage element having its first terminal connected to the cathode of said first diode and having its second terminal connected to the output of said signal-inverting amplifier; and wherein the second clamping means, in addition to said second diode, comprises said second constant voltage element having its first terminal connected to the anode of said second diode and having its second terminal connected to the output of said signal-inverting amplifier.
Claim 9
Dependent Claim
35 words
An apparatus in accordance with claim 5 wherein said potential reference elements each comprise a string of at least one forwardly-biased diode and bias-current supplying means connecting to said diodes for keeping them forward biased.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-11-18 | 1978-05-20 | 1978-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-18 | 1982-05-20 | 1982-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-18 | 1986-05-20 | 1986-11-19 | $7700.00 | Window Closed / Lapsed |