Browse Prior Art Database

ADAPTIVE OPTICS FOR OUTPUT ALIGNMENT OF ROS UNITS

IP.com Disclosure Number: IPCOM000027835D
Original Publication Date: 2000-Feb-29
Included in the Prior Art Database: 2004-Apr-09
Document File: 6 page(s) / 215K

Publishing Venue

Xerox Disclosure Journal

Abstract

For high speed electrophotographic color printing the intent is to use multiple Raster Output Scanners (ROS's) in a large machine frame. Since images from the different ROS's must be overlaid accurately, the ROSS themselves must be aligned very accurately and stay aligned through temperature cycles, accidental bumping, and etc. Thus, it is disclosed to use a deformable, flat window possibly made out of plastic. The window may be twisted and/or tilted controllably for example, in a closed loop with stepper motors to adjust the output of multiple ROS units so that the resultant color picture has all colors overlaid to specifications. Any misalignment from manufacturing and assembly or caused by temperature changes could therefore be compensated for by adjusting the output beam rather than the whole ROS.

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Page 1 of 6

XEROX DISCLOSURE JOURNAL

ADAPTIVE OPTICS FOR OUTPUT ALIGNMENT OF ROS UNITS Moritz P. Wagner

"1

Proposed Classification
U. S. C1.399/118 Int. C1. G03g 15/00

Xerox Disclosure Journal - Vol. 25, No. 1 JanuaryiFebruary 2000 29

FIG. 7

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Page 2 of 6

ADAPTIVE OPTICS FOR OUTPUT ALIGNMENT OF ROS UNITS (Cont'd)

Table 7

"2

 Alphal (degrees)

0

5

10

15

20

25

30

35

40

45

50

1.5

   d (microns)

0

0 0 0 28.1 18
54.970

81.651

109.34

139.28

172.67

21 0.70
254.38

304.57

361.83

I

I

~ 1.7

1.6

d Delta

(microns) (microns)

0 0
31.943 28.118
62.946 26.852
94.01 6 26.681
126.22 27.693
160.63 29.933
198.31 33.396
240.21 38.023
287.17 43.687
339.79 50.191
698.41 57.258

 Delta (microns)

Delta

(microns)

id

(microns)

FIG. 2

30 Xerox Disclosure Journal - Vol. 25, No. 1 JanuaryiFebruary 2000

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Page 3 of 6

ADAPTIVE OPTICS FOR OUTPUT ALIGNMENT OF ROS UNITS (Cont'd)

For high speed electrophotographic color printing the intent is to use multiple Raster Output Scanners (ROS's) in a large machine frame. Since images from the different ROS's must be overlaid accurately, the ROSS themselves must be aligned very accurately and stay aligned through temperature cycles, accidental bumping, and etc. Thus, it is disclosed to use a deformable, flat window possibly made out of plastic. The window may be twisted and/or tilted controllably for example, in a closed loop with stepper motors to adjust the output of multiple ROS units so that the resultant color picture has all colors overlaid to specifications. Any misalignment from manufacturing and assembly or caused by temperature changes could therefore be compensated for by adjusting the output beam rather than the whole ROS.

Assuming that two of the images are generated either by two ROS's or guided light beams 1 meter apart and that the machines is heating up by 5" F, possibly only on one side and further that the frame is made from steel, the images will shift and/or twist by about 30 microns. This is on the order of magnitude of a 600 dot per inch (DPI) resolution. In other words, the second image shifts by approximately one dot where a method is proposed to adjust the laser beam optically so that the images are exactly superimposed.

If a flat window is tilted, an incoming light beam is simply shifted by a certain amount as shown in Fig. 1. This shift can be derived using Equation (1) and the geometrical relationship depicted in Fig. 1 and Equation (2). As Equation (3) indicates, the shift depends on the following parameters:

Xerox Disclosure Journal - Vol. 25, No. 1 JanuaryFebruary 2000 31

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Page 4 of 6

ADAPTIVE OPTICS FOR OUTPUT ALIGNMENT OF ROS UNITS (Cont'd)

the window thickness, t

the index of refraction of the window material, n2

the angle of the window to the incoming light, a1

where:

q sin = n2 sin a2 (1)

nl = 1 for air

d=*[ sin(a, -a2)

]

cos a2

sin 2a,

JR- (3)

If...