Note: Descriptions are shown in the official language in which they were submitted.
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Background of the Invention
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My inven-tion relates -to electropho-tographi,c copiers
having a s-tationary light source. In some prior ar-t copiers,
the light source for illumina-ting the original document to be
copied is mcunted on the scanner. This construction resul-ts in
scanners of hiyh mass and consequent l:imited speed o operation.
As shown b~ Hildenbrandt in Pa-tent No. 3,758,774, the scanner mass
may be greatly decreased by using a s-tationary light source having
a parabolic cylindrical collima-ting reflector in conjunction wi-th
an upper and a lower parabolic cylindrical reflec-tor mounted on
the scanner -to illuminate the document from widely differing
angles and prevent shadowing of three dimensional objects. The
upper reflector is mounted more remote from the light source than
the illuminated region; and since the angles of incidence and
reflection are less than 45 , the upper mirror assumes a general
orientation of less than 45 from the vertical. The lower re-
flector is mounted closer to the light source than the illuminated
region; and since the angles of incidence and reflection exceed
45 , the lower mirror assumes an orientation of less than 45
from the horizontal. Because of the favorable geometry of -the
upper'reflector, it can illuminate the document over a range o~
angles from the normal approaching 90 without sub~tantially
increasing the length of the scanner. However, becaus~, of the
unfavorable geometry of the lower reflector, it can illumina-te
the document only over a limited range of angles; and the length
of the reflector and hence the scanner increases as the -tangent
of the angle of illumina-tion from the normal. The two illumi-
nating reflectors constitu-te an appreciable portion of the to-tal
mass of the scanner.
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Summary of the Invention
One objec-t o~ my inven-tion is to provide a stationar~
light source copier wherein -the illuminatiny reflec-tors have
negligible mass.
Another objec-t of my invention i5 to provide a
stationary light source copier wherein the lower reElector
illuminates the documen-t over a wide range of angles including
large angles from the normal.
Still another object of my invention is to provide a
stationary light source copier wherein the illuminating re-
flectors comprising extremely thin members maintained under
sufficient tension to prevent appreciable distortion from air
loads and inertial forces.
A further object of my invention is to provide a
stationary light source copier wherein the lower documen-t il-
luminating reflector comprises a plurality of generally horizontal
reflectors disposed in a generally vertical array.
A still further objec-t of my invention is to provide
a stationary light source electrophotographic copier wherein
heat generated by the light source is used to dry or fix
copies.
Other and further objects of my invention will appear
from the following description.
In general, my invention contemplates an electro-
photographic copier having a stationary ligh-t source directing
collimated light to a scanner provided with an upper and a
lower document illuminating reflector. The reflectors each
comprise thin members of negligible mass which are main-tained
under tension to provide rigidity. The lower reflector comprises
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a pluxality of generally horizon-tal re-Electors disposed in a
generally vertical array. The lower reflector is thus disposed
in a louvered manner, as the slats of an open venetian bl;nd.
Hea-t from the stationary light source is used to dry or Eix
copies.
Brief Descrip _ n of the Drawings
In the accompanying drawings which form par-t of the
instant specifica-tion and which are to be read in conjunction
therewith and in which like reference numerals are used to
indicate like parts in the various views:
FIGURE 1 is a front sectional view of an electro-
photographic copier embodying my invention.
FIGURE 2 is an enlarged view of the document illumi-
nating optics of FIGURE 1, showing a lower reflector having
two curved louvers.
FIGURE 2a is an electrical schematic view showing
the excitation of the illuminating lamp and heating elemen-ts.
FIGURE 3 i5 a front view of the drive mechanism for
moving the scanning optics of the copier shown in FIGURE 1.
FIGURE 4 is an enlar~ed view of document illumination
optics employing a lower reflector having six planar louvers.
FIGURE 5 is a fragmentary side view showing a curved
thin reflector maintained in tension.
FIGURE 6 is a front sectional view taken along the
line 6-6 of FIGURE 5.
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FIGURE 7 is a fragmentary ron-t view showing -the
moun-ting of -the louvered re~lector of FIGURE 4.
FIGURE 8 is a fragmentary rear view showing -the
tensioning cf the louvered reflec-ting elements oE FIG~RE ~.
~ 'IGURE 9 is a side sectional view taken cllong the
line 9-9 of FIGURE 8.
Descrip-tion of the Preferred Er~odiment
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Referring to FIGURE 1, eiongated lamp 6 and a
parabolic cylindrical reflector 8 are mounted within housing
4 of an electropho-tographic copier. Collima-ted light from
reflec-tor 8 is directed horizontally to full-rate scanning
carriage 12 which moves from -the posi-tion shown to the position
12A in scanning a document 24 positioned on glass p]ate 22. Mounted
on carriage 12 is a curved upper illuminating reflector 20 and
a lower illumina-ting reflec-tor 14. The lower reflec-tor com-
prises two curved elements or slats 16 and 18 mounted in the
fashion of a louver or open venetian blind.
~eflector 20 and sla-ts 16 and 18 of reflector 14
bring the collimated light beam to at leas-t a par-tial focus
to illuminate a narrow strip of documen-t 24 from a plurali-ty
of angles, reducing shadows from surface projections of the
document or object to be copied. Since the extent of focusing
provided by the illuminating reflec-tors is not critical and is
variable within fairly wide limits, these reflectors do not
require a high degree of optical precisionO
Ligh~ from the illuminated strip of document 24 is
reflec-ted by a planar mirror 25 moun-ted on carriage 12. Ligh-t
from mirror 26 is reflected from a half-rate mirror 28 and
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directed to a re~lex lens 31 comprisin~ lens 30 and mirror 32.
Light from lens 31, after re~lection Erom mirror 3~, passes
through a slit 35 between aper-ture plates 36 and is focused
on the photoconduc-tive surface 38 o~ drum 40.
~ s drum 40 ro-tates counterclockwise (in J~'IGURE 1),
surface 38 i9 charged by corona conductor 42, exposed to liyh-t
through aperture sli-t 35, and developed by a liquid developer
~6 in tank 44. A sheet of copy paper 48 from a s-tack 50 is
fed ~y a drive roller 52 and by guide rollers 54 into con-tact
with the developed photoconductive surface 38. Transfer corona
conductor 56 charges paper 48, causing toner particles of the
developer to be transferred from surface 38 to paper 48.
Collima-ting reflec-tor 8 is formed in a conductive
heat sink 57 which is provided with a semi-circular cylindrical
recess in which is mounted a knurled heating roller 60 driven
in synchronism with surface 38. Roller 60 is provided wi-th an
electrical resistance winding 61. Mounted beneath roller 60
is a dished plate 66 provided with an electrical resistance
winding 67. An electrical resistance winding 58 is moun-ted in
heat sink 57.
As shown in FIGURE 2a, winding 67 is energized from
wall plug 69 through regulator 68 to main-tain plate 66 at a
constant elevated temperature. Plug 69 also energizes winding
58 through regulator 59 to maintain heat sink 57 at a constant
elevated temperature. Plug 69 is connected to brushes 64 and
64a which engage respective slip rings 63 and 63a to energize
winding 61 through regulator 62 and main-tain roller 60 a-t a
constan-t elevated temperature. Plug 69 selectively exci-tes
lamp 6 through switch 7.
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~leat ~rom lamp 6 is conducted through sink 57 and is
radiated to roller 60. Hea-t from sink 57 and roller 60 is
also radiated -to plate 66. The electrical energy dissipa-ted
in resis-tance windings 58, 61, and 67 to maintain hea-t sink 57,
roller 60, an~ pla-te 66 at elevated tempera-tures is -thus
reduced. I-t will be apprecia-teA tha-t mer~ers 57, 60, ancl 6G
tend to reach the same tempera-ture because of heat radiation
therebetween. It will also be appreciated tha-t any -two o -the
three resistance windings may be omitted. To insure rapid
attainment of regulated temperature of members 60 and 66 af-ter
the copier is first started, I preferably provide windings 67
and 61, and omit only winding 58 and regulator 59.
Paper 48 is guided by rollers 55 between the heated
plate ~6 and the heated roller 60 which dry the paper and Eix
the developed image thereon. Thereafter copy paper ~8 passes
to tray 70.
FIGURE 3 shows the mechanism for moving carriage 12
and half-rate mirror 28. Cable 302 extends from cable anchor-
age 304 half-way around one groove of a two-groove sheave 306
journalled on half-rate carriage 308 which moun-ts mirror 28.
Carriage 308 rides upon rails 310 (only one of which is shown).
Cable 302 extends from sheave 306 to a clamp 310 mounted on
full-rate carriage 12. Carriage 12 also rides upon rails 310
and mounts louvered lower reflector 14, upper reflector 20 and
scanning mirror 26. From clamp 310, cable 302 passes over
pulley 314 and over roller 316 to drum 318. Mounted coaxially
with drum 318 is a pulley 320, which is driven by a belt 322
engaging a pulley 324 on the shaft of a motor 326. Cable 302
is wound around drum 318 and then passes over a -tensioning
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~ulley and over roller 316 again to a pulley 338. From pulley
338, cable 302 passes half-way around the other groove of
sheave 306 to cable anchorage 340. Tensloning pulley 328 is
journalled at one end of lever 330 which is xotatably mounted
on fixed shaft 332. Lever 330 is biased by a spr:iny 334 toward
spring anchoraye 336 to take up slack :in cahle 30~.
As is well known to the art, carriage 12 ~nd mirror
26 move a-t twice the speed oE half ra-te carri.age 308 and mirror
28. This causes the object dis-tance or length of the optical
path from document 24 to lens 31 to remain constant so that
the image on surface 38 i5 always in proper focus.
FIGURE 4 shows a document illumination system similar
to that of FIGURE 2, except that the lower reflector 402
comprises six planar elements or slats 404 through 414 mounted
in the fashion oE a louver or an open venetian blind. The
slats are disposed in a generally linear array; and each slat
extends generally orthogonal to the line of the array. Because
louvered reflector 402 is comprised of planar slats, no one
slat acting alone provides any focusing or ligh-t concentrating
effect. ~owever, the slats acting in conjunc-tion with one
another bring light to a partial focus, since each slat
illuminates the same narrow strip of documen~ 24.
The louvered reflectors 14 and 402 are advantageous
because the uppermost slat 18 or 414 is mounted neares-t the
document and can thus illuminate it at a relatively large
angle from the normal withou-t greatly increasing the length
of scanning carriage 12. The advantage may be illustrated by
constructing in FIGURE 4 an equivalent single lower reflector
422 which illuminates document 24 over -the same range of angles
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as louvered reflector 402. Reflector 422 ~ould extend from
point 419 to point 420. Point 419 is -the in-tersection of the
horizontal ligh-t ray 415 Erom beam re:Elector 8 and the light
ray 416 from the lowermost slat 404. Point 420 is the
in-tersection of p.rojec-tions of -the hori.zon-tal light ra~ 417
from beam reflec-tor 8 and -the light ray ~18 f:roin-the uppertnos-t
slat 414. The ini-tial slope oF reflector 422 at po.in~ ~19
would be -the same as sla-t 404, or slightly less than 45 ; and
the final slope of reflector 422 at point 420 would be the
same as sla-t 414, or appreciably less than 45 ~ The inordinate
length of reflector 422 would require a corresponding increase
in the length and weight of carriage 12 to support such reElec-
torO
EIGURES 5 and 6 illustrate a lightweight curved
reflector suitable for the upper reflector 20 and the curved
slats of lower reflector 14. A thin flexible reflective strip
502 formed for example of aluminum foil or of a plastic shee-t
provided with a reflective coating on one surface is secured
at its ends to mountings 504 and 506. Mounting 504 comprises
two curved members 512 and 514 be-tween which one end of
flexible strip 502 is clamped by screws 516. Rods 518 and 520
extend from the ends of clamp 512; and rod 522 extends from
the center of clamp 514. Rods 518, 520, and 522 pass with a
sliding fit through corresponding bores in side 508 of carriage
12. Each rod is provided with a head 526 and a coil spring 524
which bears against such head and against the outboard surface
of side 5080 Mounting 506 comprises curved members 528 and
530 between which the other end of flexible reflec-tor 502 is
clamped by screws 532. Clamp 5~8 is affixed to side 510 of
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carriage 12. Spri.ngs 524 maintain strip 502 in tension pro-
viding it with sufficient riyidity to resist appreci.able dis-
tortion under air loads and inertial forces. I-t will be under-
s-tood -that members 512, 51~, 528, and 530 may be s-traigh-t instead
of curved. With such construction, strip 502 w:ill be a p:l.anar
reElec-tor sui-table Eor -the slats of louvered reE:Lec-~or ~0
FIGURES 7, 8, and 9 show an al-ternate reElec-tor
construction suitable especially for planar reflec-tors, as the
louvered reflector 402. Flexible reflecting strips 40~, 406
408, 410, 412, and 414 are mounted at one end on respective
cylindrical pegs 704, 706, 708, 710, 712, and 714 secured to
member 716 of carriage 12. Each peg is provided with a longi-
tudinally extending cavity 718 having a narrow mouth. Each strip
is provided with enlarged ends 902 and 903. Ends 902 are re-
ceived and retained in cavities 718. Ends 903 are received
and retained in similar cavities 81.2 in six corresponding cylin-
drical members, such as 804 and 806. Each cylindrical member,
such as 806, is journalled on a corresponding shaft, such as
808, mounted on member 810 of carriage 12. Each cylindrical
member, such as 806,- is biased coun-terclockwise, in FIGURE 9,
by a corresponding helical spring, such as 814, the ends of
which are moun-ted in members 806 and 810 and which surrounds
shaft 808. Each cylindrical member, such as 806, is re-tained
on its shaft by a correspondin~ washer 816 and a lock nut 818
threaded upon the end of shaft 808. Spring 814 biases cylinder
806 axially against washer 816 to maintain strip 406 positioned
a proper distance from carriage member 81Ø The rotational bias
of spring 814 maintains strip 406 in tension, providing it with
sufficient rigidity to resist significant distor-tion under air
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loads and inertial forces. This tension is mainta;.ned despite
some creep or gradual elongat:ion of strip ~06 in the event i-t is
formed of a plas-tic having a reflective coa-ting on one surface.
I-t will be seen that I have accomplished -the objects
of my invention. I have provided a sta-tionary ll~ht so~rce
electrophotographic copier wherein the documen-t illuminating
reflectors mounted on the scanner have negl.igible m~ss and
comprise thin members maintained under tension. The lower
reflector illuminates the documen-t over a wide range of angles
including large angles from the normal and comprises a plu-
rality of generall.y horizontal sla-ts disposed in a generally
vertical array. Heat from the stationary light source is
coupled by conduction and radiation to dry and fix copies.
It will be understood that certain features and
subcombinations are of utility and may be employed without
reference to other features and subcombinations. This is
contemplated by and is within the scope of my claims. It is
further obvious that various changes may be made in details
within the scope of my claims withou-t departing from the spirit
of my invention. It is, therefore, to be understood that my
invention is not to be limited to the specific details shown
and described.
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