Background of the Invention
[0001] The present invention relates generally to sheet support trays and, more particularly,
to a sheet support tray for supporting a sheet of paper having a length longer than
the length of the support tray.
[0002] Modern paper handling and processing devices such as copy machines, printers, fax
machines, scanner automatic document feeders (ADF's) and the like must be adapted
to handle paper of several different lengths; typically 8-1/2 in. X 11 in. letter
size, 8-1/2 in. X 14 in. legal size and 8-9/32 in. X 11-11/16 in. A4 size. (An automatic
document feeder is described in U.S. Patent 5,232,216 of Bybee which is hereby incorporated
by reference for all that it discloses.) Accordingly, paper feeding and receiving
trays for such devices must be able to hold paper of such varying lengths. If a tray
having a length significantly shorter than the sheet of paper to be supported is used
the sheet of paper may droop at the unsupported end, sometimes sufficiently to cause
the paper to curl at the unsupported end or to becomes separated from the paper stack
on the tray or even causing the paper to fall completely out of the tray.
[0003] One obvious solution for supporting varying length sheets is to use trays which are
at least as long as the longest sheet that is to be used. However, devices equipped
with such maximum length trays generally have a larger "footprint," i.e. occupy more
desk top space or floor space than devices having smaller trays. Compactness of such
devices, particularly desk top devices, is generally an important design criterium
and thus various alternatives to such maximum length paper trays have been sought.
One alternative is a tray, shorter in length than the length of the longest sheet
of paper, which is inclined such that the unsupported end of a longer sheet is positioned
higher than the other end. Such an inclined orientation tends to prevent the unsupported
end from drooping and thus allows a relatively longer sheet to be stabily supported
than that supported by a tray arranged horizontally. Another technique which has been
used, often in combination with tray inclination, is to curve the tray along its length
to effectively increase the surface length of the sheet which is in contact with the
tray in a relatively shorter horizontal distance than would be provided by a tray
which if not curved along its length. However both tray inclination and longitudinally
arcuate trays have practical limitations. For example if a tray receiving paper from
a printer discharge port is inclined too much, the sheets being discharged into the
tray tend to buckle and cause paper jams. A tray having too much longitudinal curvature
may have similar problems with buckling and jamming and may also give paper sheets
resting therein for long periods an undesirable curled shape.
[0004] Another tray design used to support sheets of different lengths is an expandable
length tray. One implementation of this design employs a wire bracket which may be
pulled out from the terminal end of the tray to provide an extra length of support
surface for longer length sheets. However such expandable tray configurations tend
to be more expensive to produce and tend to be less durable than trays with no moving
parts. Also such trays, when expanded, have the same disadvantage as maximum length
trays, i.e. they occupy a relatively large amount of space.
Summary of the Invention
[0005] The present invention is directed to a paper tray which is capable of stabily supporting
a sheet of paper which has a length considerably longer than the length of the tray
itself and without encountering the above described problems of other paper tray designs.
[0006] Accordingly, the present invention may comprise a sheet support tray having a sheet
support portion with a first longitudinal end and a second longitudinal end. The first
end of the sheet support portion is adapted to receive a first end of a sheet of paper
in longitudinal registration therewith. The sheet of paper when supported on the sheet
support portion has an overhanging portion extending beyond the second end of the
sheet support portion. The overhanging portion has a length greater than the critical
overhang length of the paper. The sheet support portion comprises a widthwise varying
height surface portion positioned proximate the second end of the sheet support portion
adapted to bow a portion of the sheet of paper widthwise sufficiently to prevent the
overhanging portion of the sheet of paper from drooping more than the critical droop
distance of the paper.
[0007] The invention may also comprise a sheet support tray for supporting at least one
sheet of paper thereon which has a first end portion which extends outwardly from
a first end portion of the support tray by a distance greater than the critical overhang
length of the sheet of paper. The tray includes a widthwise variable height portion
positioned at the first end portion of the support tray which is constructed and arranged
to support the sheet of paper in a bowed configuration of sufficient curvature to
prevent the end portion of the sheet of paper from drooping by more than the critical
droop distance of the sheet of paper.
[0008] The invention may also comprise a sheet support tray for supporting at least one
sheet of paper thereon which has an outwardly extending paper end portion extending
outwardly from a terminal end of the support tray by a distance greater than the critical
overhang length of the sheet of paper. The tray may include a paper support; and means
in the paper support for forming a widthwise bow in the outwardly extending end portion
of the sheet of paper.
[0009] The invention may also comprise a method of supporting a sheet of paper on a paper
tray when the length of the paper is longer than the length of the paper tray by an
amount greater than the critical overhang length of the paper. The method may include
placing the sheet on the tray and bowing an overhanging end portion of the sheet widthwise
sufficiently to prevent it from drooping beyond the critical droop distance of the
sheet.
Brief Description of the Drawings
[0010] An illustrative and presently preferred embodiment of the invention is shown in the
accompanying drawing in which:
Fig. 1 is a top plan view of a sheet of paper;
Fig. 2 is an elevation view of the sheet of paper of Fig. 1;
Fig. 3 is an elevation view of a sheet of paper supported on a planar surface with
a portion thereof overhanging the planar surface;
Fig. 4 is an elevation view of a sheet of paper supported on a planar surface with
a portion thereof overhanging the planar surface by an amount equal to the critical
overhang length of the paper;
Fig. 5 is a cross-sectional end elevation view of a sheet of paper supported on a
bow-forming sheet support structure;
Fig. 6 is a side elevation view of a sheet of paper supported on the bow-forming sheet
support structure of Fig. 5;
Fig. 7 is a cross-sectional end elevation view of another bow-forming sheet support
structure having a sheet of paper supported thereon;
Fig. 8 is a cross-sectional elevation end elevation view of another bow-forming sheet
support structure having a sheet of paper supported thereon;
Fig. 9 is a cross-sectional end elevation view of dual bow-forming sheet support structure
and a sheet of paper supported thereon;
Fig. 10 is a perspective view of an automatic document feeder with an upper and lower
sheet support tray which is mounted on an optical scanner;
Fig. 11 is a top, partially cut-away plan view of the automatic document feeder of
Fig. 10;
Fig. 12 is a front end elevation view of the automatic document feeder of Fig. 10;
Fig. 13 is a perspective view of the automatic document feeder of Fig. 10 with the
upper tray portion thereof in a raised position and broken away to expose details
of the lower tray;
Fig. 14 is a perspective view of the automatic document feeder of Fig. 10 having sheets
of paper supported in the upper and the lower trays;
Fig. 15 is an end view identical to Fig. 12, except showing sheets of paper supported
in the upper and the lower trays;
Fig. 16 is a schematic side elevation view of a document discharge port and associated
planar support tray having a sheet of paper with upwardly curled leading and trailing
edges supported thereon; and
Fig. 17 is a schematic side elevation view of a document discharge port and associated
support tray having a sinusoidal support surface and having a sheet of paper with
normally upwardly curled leading and trailing edges supported thereon in a relatively
decurled configuration.
Detailed Description of the Invention
[0011] Figs. 1 and 2 illustrate a sheet of paper 10 having a central longitudinal axis AA
and a plurality of lateral axes BB, CC, etc. extending transversely of AA. The sheet
of paper has a first or front longitudinal end portion 12 having a point 13 at the
edge thereof on axis AA. The sheet of paper further includes a second longitudinal
end portion 14, a first lateral side portion 16 having a corner 17 and a second lateral
side portion 18 having a corner 19. The sheet of paper has a length "a" and a width
"b" which, in the case of a legal size sheet of paper, are 8-1/2 in. and 14 in., respectively.
The sheet of paper has an upper surface 22 and a lower surface 24. The sheet of paper
may be a relatively thick, stiff sheet of paper such as heavy bond typing paper or
a relatively thin, flexible sheet of paper such as onion skin paper, or may be of
any intermediate thickness and stiffness. The thickness/stiffness of a sheet of paper
will effect its "critical overhang length" (defined below). Sheets of paper are of
course well known in the art and Figs. 1 and 2 merely set forth terminology which
will be used herein.
[0012] Fig. 3 illustrates sheet 10 supported on a planar support surface 30 having a terminal
end 32 and having a horizontal plane PP projecting outwardly from end 32. Sheet 10
has an overhanging portion 34 extending beyond terminal end 32 of the planar support
surface by a horizontally measured distance "l". Longitudinal end portion 12 of the
sheet 10 is deflected downwardly from horizontal plane PP by gravity by a vertically
measured distance "d" referred to herein as "droop distance" or simply "droop". The
droop distance d is measured from plane PP to the center point 13 at the overhanging
end 12 of the sheet. The downward sagging of an unsupported end of a sheet is referred
to herein as "drooping." As a sheet of paper is moved so that the amount of horizontal
overhang l is increased, the amount of downward deflection or droop d tends to increase
due to the greater bending moment placed on the overhanging portion by the force of
gravity. The ratio of d to l, i.e., d/I is referred to herein as the "droop ratio"
of the sheet and varies with the overhang length. Generally, the larger the amount
of overhang, the larger the droop ratio becomes with a significant increase occurring
at a length of around 2 or 3 inches for most business quality typing paper. "Critical
overhang length" ("l
C", Fig. 4) as used herein, refers to the horizontally measured overhang length of
a sheet of paper supported in a planar configuration such as shown in Figs. 3 and
4, at the position on the support surface when the droop ratio d/l is equal to 0.25.
"Critical droop distance" (d
c) is the droop distance of the sheet when it is supported in a planar configuration
and when d/l is equal to 0.25. Although in the examples illustrated in Figs. 3 and
4 the sheet 10 is shown supported on a horizontal surface, it is to be understood
that the above discussed parameters also apply to a sheet supported on an upwardly
inclined surface wherein the overhang length l refers to the horizontal projection
of that inclined sheet and the droop d refers to the vertical drop of an end portion
of the sheet from the point that the end portion would have occupied if the sheet
extended parallel to its support surface.
[0013] As previously stated, the critical overhang length of different types of paper or
other sheets of material vary significantly depending upon the longitudinal stiffness
of the sheet. For example, a sheet of stiff, heavy weight bond paper will have a relatively
long critical overhang length whereas a thin, low tensile strength sheet of paper
such as onion skin paper will have a relatively short critical overhang length. The
vertical amount d that a given horizontal overhang length l of a sheet droops typically
varies somewhat with time and accordingly, critical overhang length and critical droop
distance as used herein are determined at a point in time when the subject sheet of
paper has been supported in an overhang position for a period of one minute. Temperature
and humidity may also effect critical overhang length and thus unless otherwise specified
herein critical overhang length l
C for a sheet of paper is to be measured at standard temperature and humidity conditions
such as are typically found in most modern air conditioned office environments.
[0014] Figs. 5 and 6 illustrate one embodiment of a bow-forming sheet support structure
40. In this embodiment, the bow-forming sheet support structure comprises first and
second elongate, parallel rib members 42, 44 fixedly supported on a cross member 45.
The rib members 42, 44 are spaced sufficiently far apart to cause the central longitudinal
axis AA of the paper, including point 13, to be deflected downwardly relative to the
first and second lateral side portions 16, 18 of the sheet. Thus the sheet has a bow-shaped
cross section when supported by this structure. The relative amount of bowing at any
cross sectional portion of the sheet may be represented by a bow ratio "e/f" where
"e" is the vertical height between axis AA and a line drawn between the edges of lateral
side portions 16, 18 of the sheet and where "f" represents the distance between lateral
edges. In one preferred embodiment of the invention, the bow ratio of the paper e/f
at the terminal end 32 of support structure 40 is sufficient so that the horizontal
length l of the sheet is at least 25% greater than the critical overhang length l
C of the sheet at the overhang position where the bowed sheet droops by an amount d
C. (It is to be understood that the parameters l
C and d
C are always determined for the subject sheet when the sheet is supported in a planar
configuration.) A sheet having such a horizontal overhang extension (1.25l
c) or greater extension without drooping more than the critical droop distance d
C is referred to herein as being erect or being in an erect state. A bow ratio e/f
of about 0.02 or more in the cross section of the paper positioned at the terminal
end 32 of the support structure is sufficient to place sheet of typical business grade
typing paper such as twenty pound, bond office stationary, in an erect state.
[0015] The bow-forming structure of Figs. 5 and 6 illustrates a bow formed by two spaced-apart
ribs with no lower support for the paper, i.e. the depth e to which the paper sags
is limited only by the tensile strength of the paper in the width direction. Fig.
7 illustrates another bow-forming structure viewed from a terminal end 32 thereof,
with the paper sheet supported thereon shown in cross section. This structure has
a continuous bow-shaped surface 54 which supports the paper sheet at all points across
the width thereof. Fig. 8 is an end view of another embodiment of a support structure
in which the paper is supported by a multi-ribbed, bow-shaped support surface 56 comprising
ribs 57 through 63.
[0016] Fig. 9 illustrates a compound bow-forming support structure comprising outer ribs
65, 69 positioned at a first elevation and central rib 67 positioned at a second elevation.
The compound bow shape could be formed by use of many more ribs or a continuous surface
as well as the 3 rib configuration. For supporting extremely wide sheets, multiple
compound bow-shaped configurations could be used. Thus, Fig. 9, as well as Figs. 5-8,
all represent bow-forming structures which may be used to place a sheet of paper in
a configuration having greater longitudinal stiffness than a flat sheet of paper thus
increasing the length I which may overhangs the end portion 32 of a document support
surface without drooping.
[0017] Figs. 5 and 6 illustrate a bow forming structure that urges a sheet of paper supported
thereon into a bow shaped configuration along its entire length. In many applications
it is desirable that the second end 14 of the sheet remain in a planar configuration.
For example an infeed tray or discharge tray of a printer or automatic document handler
may experience paper jamming if the end of the paper proximate the infeed/discharge
port is not flat. In such applications it is generally desirable to have a bow forming
structure positioned only at the end of the support structure remote from the infeed/discharge
port and extending no more than about one third the length of the paper sheet. Paper
trays incorporating this concept are disclosed below.
[0018] Fig. 10 shows an automatic document feeder 90 mounted on an optical scanner 92. The
automatic document feeder 90 includes an upper paper tray 94 which acts as an infeed
tray. The tray has a first (front) longitudinal end 96, a second (rear) longitudinal
end 98, a first lateral side 100 and a second lateral side 101. The tray includes
a paper support surface 102 adapted to contact the bottom surface 24 of a sheet of
paper 10 positioned thereon. The paper support surface 102 may comprise a generally
flat, ribbed surface 103 having longitudinally extending ribs 104, 106, etc. which
may be spaced at intervals of about 1/8" and which may have a height above a flat
surface of about 1/64". The rib surface 103 terminates proximate the rear longitudinal
end 94 of the support tray at rear border 105 and thereafter, the surface indicated
as 107, may be flat and unribbed. The tray also includes an unribbed multi-curved
surface 110 located proximate end 96 which is defined, in part, by a cut-out 112 positioned
at the center of front longitudinal end 96. Tray 94 may include vertically projecting
guide rails 114, 116 positioned adjacent to the lateral sides thereof. The guide rails
comprise vertical surfaces 117, 119. Tray 94 may be partially covered by a housing
lid 118 which may house drive rollers, etc. (not shown) which may operate in a conventional
manner to draw paper stacked on the support tray into the automatic document feeder
in feed direction 119. A vertical gap 120 between the front bottom portion of lid
118 and paper support surface 102, which may be e.g., "1/2" initially, reducing to
about 1/8 inch about 3/4 inch re farther in, allows papers stacked on surface 102
to slide under the housing lid 118 and come into abutting contact with a paper abutment
surface or stop 122. A paper infeed mechanism (not shown), which may be of a conventional
type, pulls sheets from the top of the paper stack one at a time and moves each sheet
through the automatic document feeder and then out a discharge port onto lower paper
tray 210. Paper infeed an handling mechanisms for automatic document feeders are well
known in the art and will thus not be further described.
[0019] Upper tray longitudinal end 96 terminates at vertical terminal wall portion 130 which
intersects vertical terminal wall portions 132, 134 of lateral rails 114 and 116 at
corners 136 and 138.
[0020] Unribbed surface 110 includes a laterally extending border 142 and longitudinally
extending borders 146, 148 which border the ribbed surface portion 103. The front
end cut-out 112 may be defined by laterally and vertically extending terminal wall
portion 152 and longitudinally and vertically extending wall portions 154 and 156.
Wall portion 152 intersects the curved upper surface of unribbed surface 110 at intersection
line 153. Vertical wall portions 154 and 156 intersect the curved upper surface of
unribbed surface 110 at linear intersection lines 155 and 157. Longitudinally extending
wall portions 154, 156 intersect vertical terminal wall 130 at corners 158, 160. A
laterally extending, generally rectangular-shaped portion 162 of surface 110, Fig.
11, slopes forwardly and downwardly and may have a radius of curvature of about 6-1/2
inches and a total vertical drop of about 1/4 inches. Unribbed surface 110 comprises
first and second longitudinally extending, generally rectangular portions 164 and
166 positioned in mirror image relationship. These longitudinally extending portions
slope inwardly and downwardly and may comprise a radius of curvature of about 6-12
inches and a total vertical drop of about 1/inch. The laterally extending portion
162 intersects with the longitudinally extending portions 164, 166 at intersection
regions 168, 170, respectively. The curvature in these intersection regions may vary
to provide a smooth blending of the curves of the respective curved portions 162,
164 and 166.
[0021] The distance between vertical terminal walls 117, 119 may be about 8 and 3/4 inches.
The length of the paper tray between longitudinal ends 96 and 98 thereof, i.e., between
vertical terminal wall portion 130 and abutment surface 122 measured along the rib
surface portion next adjacent one of the guide rails may be about 10 and ½ inches.
The unribbed area 140 may have a width measured along border 142 of about 7 and ½
inches and may have a length measured from border 142 to vertical wall 130 along borders
146 and 148 of about 4 and 5/8 inches. The corners 158, 160 of the cut-out portion
are positioned a longitudinal distance "i" from corner portions 136, 138 of the guide
rail and i may be about 3/8 inches. Front vertical wall 130 may have a radius of curvature
in the plan view of Fig. 11 of about 30 inches. The drop "h" from border 142 to edges
153, 155, 157, as illustrated in Fig. 12, may be about 1/4 inches. The longitudinal
length of intersection line 155 and intersection line 157 may each be about 3 inches.
The lateral dimension of intersection line 153 may be about 4-1/4.
[0022] The ribbed surface portion 103 of the paper support surface 102 may slope downwardly
and rearwardly from a point about even longitudinally with cut-out wall 152 and may
extend forwardly generally horizontally from that location. In one preferred embodiment,
the vertical surface 152 of the cut-out may be about 7-1/2" (measured along the surface)
forward of abutment surface 122 and the downward slope from the portion of the rib
surface adjacent 152 may extend to about 1 inch forward of abutment surface 122. The
rib surface 103 may terminate at 105 and a flat, unribbed surface 107 may extend from
the edge of the rib surface to the abutment surface 122. The total drop of the rib
surface as it proceeds rearwardly may be about 3-4 inch. The front generally flat
portion of the rib surface is indicated at 174 and 176 and comprises a portion on
either side of the unribbed surface.
[0023] As illustrated in Figs. 10-12, 14 and 15 in phantom, the paper support surface 102
of the upper paper tray 94 may, in the alternative, be provided with generally half
disk-shaped paper guides 182, 184 adapted to guide legal/letter width sheets and A4
width sheets, respectively. Each guide may have a thickness of about 1/8 inch and
may be about 1 inch long and about 3/16 inch high and may have a radius of curvature
of about 3/4 inch. guide 182 may have a central longitudinal axis positioned parallel
to surface 119 and spaced 9/16 inch therefrom. Guide 184 may have its central longitudinal
axis spaced 5/16 inch from surface 119. The rear edge of guide 182 may be at the same
longitudinal position as border 142. The forward edge of guide 184 may be positioned
about 7/16 inch rearwardly of corner 160. In operation, guide 182 and surface 117
serves to guide a lateral edge portion of a legal/letter sized sheet of paper to maintain
it in a straight orientation in the tray. Guide 184 and surface 117 perform the same
function for A4 width sheets. When a letter/legal width sheet is discharged into the
paper tray, the leading edge rides up and over guide 184. Thus, guide 184 acts to
support a portion of a letter/legal-sized sheet above the surface of tray 102 and
acts as a portion of the tray structure which causes the end of the supported sheet
to adopt a generally bow-shaped configuration.
[0024] A lower paper tray 210 which may comprise a discharge paper tray is best shown in
Fig. 13 which shows the upper paper tray 90 pivoted upwardly and broken away to expose
details of the lower paper tray. The lower paper tray 210 includes a first or front
longitudinal end 212, a second or rear longitudinal end 214 and a first lateral side
216. A first longitudinally extending guide rail 222, having a top surface 223 and
an inner vertical side surface 224, is positioned adjacent the first lateral side
216 and a second longitudinally extending guide rail 226 having a top surface 227
and a vertical surface (not shown) in mirror image relationship to surface 224 is
positioned adjacent second lateral side 218. The lower tray 210 may comprise a flat,
horizontally extending base surface 232. A rear abutment surface 234 projects vertically
upwardly from the flat horizontally extending surface. A plurality of generally identically
shaped vertical ribs 236, 238, 240, 242, 244, 246, which may each be about 1/16 inch
thick, extend parallel to vertical surface 224 of guide rail 222. First rib 236 may
be positioned one inch from guide rail surface 224, second vertical rib 238 may be
positioned one inch from vertical rib 236, vertical rib 240 may be positioned 3/4
inch from vertical rib 238. Vertical rib 242 may be positioned 2 and ½ inches from
vertical rib 240. Vertical rib 244 may be positioned 3/4 inch from rib 242. Rib 246
may be positioned one inch from rib 244 and one inch from the inner vertical wall
surface of second guide rail 226.
[0025] As shown by Fig. 13, each of the vertically extending ribs 236, 238, etc. may have
a generally sine wave-shaped configuration. The first end of each rib 250 may comprise
a first trough portion of the rib which may have a height of 0 inches above the flat,
horizontal-extending base 232. This point 250 on the rib may be positioned 2-1/4 inches
forward of abutment surface 234. Each rib has a rib crest 252 positioned 5-1/4 inches
horizontally forward of abutment surface 234 and may have a height of 3/8 inches above
the flat base surface. Each rib has a second trough portion 254 which may be the front
terminal end of the rib and may be positioned 10 inches horizontally forward of abutment
surface 234 and may have a height of about 1/8 inch above the base surface. The forward
end of each rib may terminate at a shoulder surface 258 which is in turn connected
to an upwardly and forwardly ramping surface 256. The top of the shoulder surface
258 may have the same height as the second trough 254 of each rib. The forward edge
260 of the upwardly ramping surface may be positioned 11-1/2 inches horizontally forwardly
of abutment surface 234. The front edge 260 of the upwardly ramping surface intersects
a top surface 264 of a horizontally extending front rim portion 262. The top surface
264 is coplanar with the top surfaces 223 and 229 of the guide rails 222, 226. The
front rim 260 and the upwardly ramping surface 256 are integrally connected with a
generally truncated converging half pipe-shaped portion 265 which terminates in an
inverted handlebar mustache-shaped portion 266. The truncated converging half pipe-shaped
portion 265 includes a curved, concave upward surface 267 which intersects the upwardly
ramping surface 256 at intersection lines 269, 271 which in turn intersect at point
273 at the shoulder 258 of upwardly ramping surface 256. The inverted handlebar mustache-shaped
portion 266 comprises a first laterally extending handlebar portion 268 having a slightly
inwardly and downwardly curving upper surface 270 which may have a radius of curvature
of about 1-3/4 inches. The handlebar portion 268 may comprise a rear surface 272 sloping
downwardly and rearwardly which is a continuation of upwardly and forwardly ramping
surface 256. The inverted handlebar mustache-shaped portion may have a second laterally
extending handlebar portion 276 which may be a mirror image of portion 268. The highest
points on the handlebar portions forms a second crest of the sinusoidal support surface
and may be about 1 inch higher than the first trough portion 250. The inverted handlebar
mustache-shaped portion 266 may comprise an intermediate portion 280 having a generally
bow-shaped upper surface 282 which is a continuation of surface 267 and which may
have a radius of curvature "r" shown in Fig. 12 of about 5-1/2 inches. As previously
discussed, the inverted, mustache-shaped portion 266 intersects the upwardly ramping
surface 256 at intersection lines 269, 271. The depth "m" of the bow-shaped portion
below a plane MM across the top of the handlebar-shaped portion may be approximately
3/4 inch. The truncated converging half pipe-shape of portion 265 causes a slight
gap, e.g. 1/16 inch (Fig. 15) between the surface of an 8 and ½ inch long piece of
paper supported on the lower support tray and the upper surface 282 of the inverted
mustache-shaped portion 266 such that a person may slide his or her finger underneath
the sheet of paper to lift it from the tray. If a longer sheet of paper is supported
in the lower tray, the gap increases with the length of the paper until the terminal
end of the paper is even with the vertically extending face 288 of the inverted mustache-shaped
portion.
[0026] It will be appreciated from the foregoing description of the upper sheet support
tray and also from the descriptions of bow-forming surfaces, such as illustrated in
Figs. 5-8, that the truncated converging half pipe-shaped portion 265 and particularly
the inverted handlebar mustache-shaped portion 266 thereof is a sheet bow-forming
structure. At the inverted mustache shaped portion 266 this bow-forming structure
has a depth m of about 3/4 inches and a width n of about 6-1/8 inches and is capable
of supporting sheet in a generally horizontally erect state at a length substantially
longer, e.g. at least 25% longer, than the critical overhang length of the paper due
to the bow formed in the paper by the inverted handlebar mustache-shaped portion.
The bow formed may have a radius of curvature greater than that of the bow of the
inverted mustache-shaped portion if the paper supported is sufficiently stiff to prevent
deformation to the entire depth m of the inverted mustache-shaped portion. However,
the paper may be made to more closely assume the shape of the inverted mustache-shaped
portion by urging the paper downwardly as by positioning one's hand on the paper and
pushing downwardly or through the force of gravity due to the weight of a stack of
paper supported on the lower paper support tray. Even after release of such downward
pressure the paper tends to stay in this more bow-shaped configuration which in turn
allows for greater horizontal projection of the paper from the tray end without drooping.
A similar bow-forming process occurs in the upper support tray as well, except that
there is no lower limit to the deformation of the paper provided by a support surface
and thus, the paper itself will provide the maximum limit of deformation. It is to
be appreciated that the bow-forming portion of both the upper tray and the lower tray
are provided only at the front ends thereof. This configuration allows the paper to
maintain a generally, horizontally-flat orientation across the rear longitudinal end
thereof facilitating interface with the paper infeed mechanism 290, etc. of the ADF
associated with the upper tray 90 and the paper discharge mechanism 292, etc. associated
with the lower tray 210. Thus, only the forward end 12 of a sheet supported in each
of these support trays is placed in the bow-shaped configuration which provides longitudinal
rigidity while enabling the rear end portion 14 of the paper to remain relatively
flexible and positioned in a generally laterally flat orientation on the associated
tray.
[0027] Fig. 14 illustrates sheets of paper 10 supported on both the upper support tray and
the lower support tray without drooping at a distance beyond the critical overhang
length of the paper. Fig. 15 is an end view of Fig. 14.
[0028] Fig. 16 illustrates a problem associated with the discharge of sheets of paper onto
a flat paper support tray 308. A sheet 310 is discharged into the support tray 308
in feed direction 312 and comprises a leading edge 314 and a trailing edge 316 which
tend to curl upwardly after the paper is discharged from paper discharge port 318.
This upward curling of the edge of the paper may be produced as when paper is fed
through a laser printer or some other device which causes differential heating of
the paper. Each upwardly curved end may rise as much as 1 inch or more. The problem
with discharging paper having curled-up ends onto a flat support tray 308 is that
an incoming sheet of paper 320 having a leading edge portion 322 may come into contact
with a trailing edge portion 316 of the first sheet causing the leading edge of the
incoming sheet to be driven under, rather than over, the first sheet and tending to
cause paper jams in the support tray and/or disturbing the order of the sheets. Fig.
17 illustrates the support of sheet 310 on a sinusoidal support surface 330 having
a first trough 332, a crest 334, and a second trough 336 such as that described for
the rib portions of the lower support tray 210. It may be seen that this sinusoidal
support surface shape causes the ends of the paper 314, 316 to be positioned in a
generally flat orientation on the support tray resulting in the leading edge 322 of
the next incoming sheet of paper passing over, rather than under, the trailing edge
316 of the first sheet and avoiding paper jams. It has also been discovered that causing
the leading edge 314 of the sheet to move upwardly over a support surface such as
provided by the upwardly ramping surface 256 of the lower support tray results in
improved paper handling by slowing the movement of the paper out of the tray to prevent
the paper from sliding out of the try, even in a paper tray configuration where the
paper does not project outwardly from the tray sufficiently such that it needs a bow
formed at the end thereof for overhang rigidity.
[0029] It is contemplated that the inventive concepts herein described may be variously
otherwise embodied and it is intended that the appended claims be construed to include
alternative embodiments of the invention except insofar as limited by the prior art.
1. A sheet support tray for supporting at least one sheet (10) of paper thereon which
has an outwardly extending paper end portion (34) extending outwardly from a terminal
end (32) of said support tray by a distance greater than the critical overhang length
of said sheet of paper comprising:
a paper support (40); and
means (42, 44, 45) in said paper support for forming a widthwise bow in said outwardly
extending end portion (34) of said sheet (10) of paper.
2. The sheet support tray of claim 1 said widthwise bow being of sufficient curvature
to prevent said outwardly extending portion (34) of said sheet of paper from drooping
more than the critical droop distance of the paper.
3. The sheet support tray of claim 2, said widthwise bow being upwardly concave.
4. The sheet support tray of claim 1, said widthwise bow having a bow depth (e) of at
least one eighth inch.
5. A method of supporting a sheet of paper (10) on a paper tray (40) when the length
of the paper (10) is longer than the length of the paper tray (40) by an amount greater
than the critical overhang length of the paper comprising:
placing the sheet (10) on the tray (40); and
bowing an overhanging end portion (34) of the sheet widthwise sufficiently to prevent
it from drooping beyond the critical droop distance of the sheet.
6. The method of claim 5 wherein bowing the sheet comprises urging the sheet (10) against
a nonplanar surface (54) of the paper tray.
7. The method of claim 6 wherein urging the sheet (10) against a nonplanar surface (54)
of the paper tray comprises urging the sheet with gravity.
8. The method of claim 6 wherein urging the sheet (10) against a nonplanar surface (54)
of the paper tray comprises urging the sheet by momentarily applying hand pressure
to the sheet.
9. The method of claim 5 wherein bowing the sheet comprises bowing a terminal end portion
of the sheet.
10. The method of claim 5 comprising maintaining the end (14) of the sheet (10) opposite
the overhanging end portion (34,12) in a generally planar configuration.