Patent EP0412036A2 successfully refreshed from Google Patents.
EP0412036A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Pel placement correction in the scan dimension of a multiple beam laser scanning system
Assignee: International Business Machines Corp
•
Filing: 1990-06-19
•
Granted: —
•
Expires: 2010-06-19
Abstract
Abstract This is an electronic scheme for correcting mechanical misalignment and electrical delays from laser beam to laser beam in the scan direction of a multiple beam laser scanning system for use in an electrophotographic machine. The position at which a reference beam is turned on is sensed and adjusted to a desired position. Thereafter, the positions at which non-reference laser beams are turned on are sensed and adjusted to the desired position. In one embodiment, the energization of laser beams is positioned at the trailing edge of the second element of a photodetector. In a second embodiment, the point of full laser energy is matched, beam to beam, at the junction of the same two elements in a CCD array. Programmable delay lines are used to obtain sub-pel resolution.
Inventors
- 👤 Joan Stagaman Goddard
- 👤 Wayne Arlan Overby
- 👤 James Alfred Valent
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-10 02:05
CPC Classifications
G; G06; G06K; G06K15/00; G06K15/02; G06K15/12; G06K15/1238; G06K15/1257; G06K15/1261; H; H04; H04N; H04N1/00; H04N1/04; H04N1/047; H04N1/053; H04N1/19; H04N1/191; H04N1/1911; H04N1/113; H04N1/1135; H04N1/12; H04N2201/00; H04N2201/024; H04N2201/02406; H04N2201/02439; H04N2201/04; H04N2201/047; H04N2201/04701; H04N2201/0471; H04N2201/04712; H04N2201/04732; H04N2201/04744; H04N2201/04753; H04N2201/04758; H04N2201/04767; H04N2201/04781; H04N2201/04786; H04N2201/04794
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
110 words
A method of correcting picture element (pel) placement in the scan direction of a multiple beam laser scanning system comprising the steps of : sensing the position at which a reference laser beam turns on; adjusting the position of said reference laser beam to turn on at a desired point; sensing the position at which a non-reference laser beam turns on; adjusting the position of said non-reference laser beam to turn on at the same position as said refer ence laser beam; and writing pels produced by both reference and non-ref erence beams in accordance with the adjusted positions to thereby correct for the effects of mechanical and electrical skew.
Claim 2
Independent Claim
110 words
A method of correcting picture element (pel) placement in the scan direction of a multiple beam laser scanning system comprising the steps of : sensing the position at which a reference laser beam turns on; adjusting the position of said reference laser beam to turn on at a desired point; sensing the position at which a non-reference laser beam turns on; adjusting the position of said non-reference laser beam to turn on at the same position as said refer ence laser beam; and writing pels produced by both reference and non-ref erence beams in accordance with the adjusted positions to thereby correct for the effects of mechanical and electrical skew.
Claim 3
Dependent Claim
75 words
The method of claim 1 wherein the step of sensing the position at which said reference laser beam turns on, includes the steps of : scanning said reference beam in an energized state across a first photodetector element to generate a reference pulse; turning said reference beam off; scanning said reference beam across a second photo detector element and turning said reference beam on in time to generate a first pulse from said second element.
Claim 4
Dependent Claim
58 words
The method of claim 2 wherein the step of adjusting the position of said reference beam includes the steps of : repositioning the leading edge of said first pulse so that it energizes said second photodetector element at the trailing edge thereof to thereby establish a reference beam time period between said reference pulse and said first pulse.
Claim 5
Dependent Claim
60 words
The method of claim 3 wherein the steps of sensing the position of a non-reference beam includes the steps of : producing said reference pulse by said reference beam; turning said reference beam off; scanning said non-reference beam across said second photodetector element and turning said non-reference beam on in tine to generate a non-reference pulse from said second element.
Claim 6
Dependent Claim
58 words
The method of claim 4 wherein the step of adjusting the position of said non-reference beam includes the steps of : repositioning the leading edge of said non-reference pulse so that it energizes said second photodetector element at the trailing edge thereof to thereby establish a non-reference beam time period between said reference pulse and said non-reference pulse.
Claim 7
Dependent Claim
168 words
The method of claim 5 wherein the step of repo sitioning the leading edge of said first pulse in cludes the steps of : producing a chain of clock pulses gated to said reference pulse; producing said first pulse on a first scan of said reference beam; determining the number of whole clock pulses between said reference pulse and said first pulse; incrementing the number of whole clock pulses be tween the reference pulse and the first pulse by one on each successive scan of said reference beam until said first pulse is no longer produced, then backing off said number of whole clock pulses; producing a succession of incremental pulses of equal duration during the clock pulse following the last of the whole clock pulses determined in the step immediately above; determining the number of incremental pulses prior to extinguishment of said first pulse; adding the whole number of clock pulses to the num ber of incremental pulses to obtain a measure of said reference time period.
Claim 8
Dependent Claim
165 words
The method of claim 6 wherein the step of repo sitioning the leading edge of said non-reference pulse includes the steps of : producing said non-reference pulse on a first scan of said non-reference beam; determining the number of whole clock pulses between said reference pulse ard said non-reference pulse; incrementing the number of whole clock pulses be tween said reference pulse and said non-reference pulse by one on each successive scan of said non-reference beam until said non-reference pulse is no longer produced, then backing off said number of whole clock pulses by one to produce a determined number of clock pulses; producing a succession of incremental pulses of equal duration during the clock pulse following the last whole clock pulse determined in the step immediately above; determining the number of incremental pulses prior to extinguishment of said non-reference pulse; adding the determined number of whole clock pulses to the number of incremental pulses to obtain a measure of said non-reference beam time period.
Claim 9
Dependent Claim
51 words
The method of claim 1 wherein the step of sensing the position at which said reference laser beam turns on includes the steps of : scanning said reference beam in a de-energized state across a CCD array; turning said reference beam on in time to produce signals from said CCD array.
Claim 10
Dependent Claim
43 words
The method of claim 8 wherein the step of adjusting the position of said reference beam is accomplished by moving the turn on point of the reference beam until full laser energy is sensed at a junction of directly adjacent CCD array elements.
Claim 11
Dependent Claim
48 words
The method of claim 9 wherein the step of sensing the position of said non-reference beam includes the steps of : scanning said non-reference beam in a de-energized state across said CCD array; turning on said non-reference beam in time to pro duce signals from said CCD array.
Claim 12
Dependent Claim
42 words
The method of claim 10 wherein said step of adjusting the position of said non-reference beam is accomplished by moving the turn-on point of said non-reference beam until full laser energy is sensed at a junction of directly adjacent CCD array elements.
Claim 13
Dependent Claim
86 words
The method of claim 11 wherein the step of adjusting the position of the reference beam further includes the steps of: producing a succession of incremental pulses during the period in which the reference laser beam tra verses the CCD element immediately prior to that adjacent CCD element first sensing full reference beam laser energy; determining the number of incremental pulses prior to sensing full laser energy; moving said turn on point of said reference laser beam in accordance with the determined number of incremental pulses.
Claim 14
Dependent Claim
125 words
The method of claim 12 wherein the step of adjusting the position of the non-reference beam further includes the steps of : moving the turn on point of said non-reference beam so that full laser energy is first sensed in the CCD array element immediately following that CCD element identified as first sensing full laser energy in claim 12; producing a succession of incremental laser beams during the period in which the non-reference laser beam traverses the CCD element immediately prior to that adjacent CCD element first sensing non-ref erence laser beam full energy; determining the number of incremental pulses prior to sensing full laser energy; moving said turn on point of said non-reference laser beam in accordance with the determined number of incremental pulses.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.