Paper feed enhancer for printer feeder

A feed enhancer for eliminating an unevenness in height from a paper stack to be printed by a printer. The printer has a paper feeder including a paper tray for storage of the paper stack on a top surface thereof and for feeding individual paper from the paper stack into the printer for subsequent printing. The feed enhancer has an elongated strip disposed at the top surface of the paper tray and positioned perpendicular to a direction in which the individual paper is fed into the printer such that the feed enhancer evens out the unevenness in height of the paper stack in an area of the paper stack that is to be fed into the printer. Also provided are a printer and printer tray having the feed enhancer of the present invention.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The field of art to which this invention relates is-printers, in
 particular, a feed enhancer for a high volume printer having a top-feeder
 in which paper stock having labels and/or perforations are fed into the
 printer.
 2. Description of the Related Art
 In printers of the prior art, particularly those which employ a top-feeder
 for storing and feeding paper into the printer, paper which has a label
 affixed thereto or which has one or more perforations presents a problem
 in that it does not properly feed into the printer. Printing on such paper
 is particularly troublesome because the paper does not sit flatly upon a
 feeder tray due to the labels or perforations.
 A typical printer 100 of the prior art having such a top-feeder paper feed
 arrangement is shown in FIGS. 1A and 1B. The top-feeder 102 generally
 includes a paper tray 103 and employs a pick roller 104 for contacting and
 feeding a sheet of paper 106 from the top of a paper stack 108 into the
 printer 100. A gearbox and motor assembly 110 drive the pinch roller as
 necessary to feed the paper 108. If the paper in the paper stack 108 does
 not sit flatly on the paper tray 103, the pick roller 104, which is
 generally located in the center of the paper along a central axis C--C,
 does not effectively engage and feed the paper 108 into the printer 100.
 Examples of types of paper which do not lie flatly on the paper tray 103,
 are illustrated in FIGS. 2A-2C. Respective stacks of the types of paper
 illustrated in FIGS. 2A-2C are illustrated in FIGS. 3A-3C together with
 the paper tray 103 and pick roller 104 of FIG. 1.
 FIG. 2A illustrates a sheet of paper 200 having a label 202 on one side.
 The label 202 adds a significant thickness to the overall thickness of the
 sheet of paper 200 in the area of the label 202. As can be seen in FIG.
 3A, when stacked on a paper tray 103 of a printer 100 having a top feeder
 102, the paper 200 has a greater height (H1) on the side with the label
 202 than the height (H2) on the side without the label 202. Because of
 this uneven height (H1&gt;H2), the pick roller 104 only engages the paper 200
 on a portion of its width and causes the paper 200 to rotate as it is
 being fed into the printer 100.
 FIG. 2B illustrates a sheet of paper 210, having two perforations 212. The
 perforations 212 run in the same direction as the direction that the paper
 210 is fed into the printer 100. As can be seen in FIG. 3B, when stacked
 on a paper tray 103 of a printer 100 having a top feeder 102, the paper
 210 has a greater height (H3) on the sides than in the middle (H4)
 (alternatively, if the paper stack is turned 180 degrees such that the top
 sheet is at the bottom, the paper stack will have a peak at each of the
 perforations resulting in an M-shaped stack). Because of this uneven
 height (H3&gt;H4), the pick roller 104 does not properly engage the paper 210
 leading to improper feeding of the paper 210 into the printer 100.
 FIG. 2C illustrates a sheet of paper 220, having a single perforation 222.
 The perforation 222 runs in a direction perpendicular to the direction
 that the paper 220 is fed into the printer 100. As can be seen in FIG. 3C,
 when stacked on a paper tray 103 of a printer 100 having a top feeder 102,
 looking from the side of the paper stack, a portion 224 of the paper 220
 decreases in height from the perforation 222 to the end of the paper 226.
 (alternatively, if the paper stack is turned 180 degrees such that the top
 sheet is at the bottom, the portion 224 will increase in height from the
 perforation 222 to the end of the paper 226). Because of this uneven
 height, the pick roller 104 does not properly engage the paper 210 leading
 to improper feeding of the paper 210 into the printer 100.
 These problems ultimately cause the paper 200, 210, 220 to jam in the
 printer 100 resulting in downtime of the printer 100 and possibly,
 expensive maintenance. It should be apparent to those skilled in the art,
 that these paper configurations are given by way of example only and not
 as an exhaustive listing thereof. For example the paper may have a
 combination of those shown or others not shown such as pre-printed stock
 which has a tendency to curl when stacked upon the printer tray 103.
 Devices are known in the prior art for addressing the uneven thickness and
 shape of paper to be fed into a printer. The prior art teaches devices for
 compensating for variations in the thickness between individual sheets of
 a paper stack being fed into a printer. The prior art devices achieve
 their objective by sensing the thickness of each piece of paper being fed
 into the printer and adjusting certain parameters within the printer
 according to the sensed thickness.
 While these devices have their advantages, they are generally complex,
 costly, and difficult to implement on existing printer designs.
 For these reasons a feed enhancer is needed which is simple, inexpensive,
 easy to retrofit onto existing printers and which can compensate for paper
 stacks that do not lie flatly and evenly upon a printer feeder which are
 to be fed into a printer, particularly one which employs a top-feeder
 system.
 SUMMARY OF THE INVENTION
 Therefore, it is an object of the present invention to provide a simple
 feed enhancer for a printer.
 It is a yet a further object of the present invention to provide an
 inexpensive feed enhancer for a printer.
 It is still yet another object of the present invention to provide a feed
 enhancer which is easily retrofitted onto existing printers.
 Accordingly, the present invention provides a feed enhancer disposed on a
 surface of a paper feeder tray to compensate for variations in height
 and/or shape of a paper stack placed upon the paper feeder tray caused by
 labels or perforations in/on the individual paper in the stack. The feed
 enhancer is disposed perpendicular to the direction that the paper is fed
 into the printer.
 In a first variation of the feed enhancer of the present invention, a feed
 enhancer for eliminating an unevenness in height from a paper stack to be
 printed by a printer is provided. The printer has a paper feeder including
 a paper tray for storage of the paper stack on a top surface thereof and
 for feeding individual paper from the paper stack into the printer for
 subsequent printing. The feed enhancer comprises an elongated strip
 disposed at the top surface of the paper tray and positioned perpendicular
 to a direction in which the individual paper is fed into the printer such
 that the feed enhancer evens out the unevenness in height of the paper
 stack in an area of the paper stack that is to be fed into the printer.
 In a second variation of the feed enhancer of the present invention, a
 printer tray for eliminating an unevenness in height from a paper stack to
 be printed by a printer is provided. The printer has a paper feeder
 including the paper tray for storage of the paper stack on a top surface
 thereof and for feeding individual paper from the paper stack into the
 printer for subsequent printing. The printer tray comprises a feed
 enhancer having a heightened portion disposed at the top surface of the
 paper tray and positioned perpendicular to a direction in which the
 individual paper is fed into the printer such that the feed enhancer evens
 out the unevenness in height of the paper stack in an area of the paper
 stack that is to be fed into the printer.
 In a third variation of the feed enhancer of the present invention, a
 printer for eliminating an unevenness in height from a paper stack to be
 printed is provided. The printer has a paper feeder including a paper tray
 for storage of the paper stack on a top surface thereof and for feeding
 individual paper from the paper stack into the printer for subsequent
 printing. The printer comprises a feed enhancer having a heightened
 portion disposed at the top surface of the paper tray and positioned
 perpendicular to a direction in which the individual paper is fed into the
 printer such that the feed enhancer evens out the unevenness in height of
 the paper stack in an area of the paper stack that is to be fed into the
 printer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 Although this invention is applicable to numerous and various types of
 printers and paper, it has been found particularly useful in the
 environment of printers employing a top-feeder and the types of paper
 illustrated in FIGS. 2A-2C. Therefore, without limiting the applicability
 of the invention to top-feeder printers and the types of paper illustrated
 in FIGS. 2A-2C, the invention will be described in such environment.
 Referring now in detail to FIG. 4, a first embodiment of a feed enhancer
 for eliminating an unevenness in height from a paper stack to be printed
 upon by a printer 100 is provided. The first embodiment feed enhancer is
 generally referred to by reference numeral 400. The feed enhancer 400
 comprises an elongated strip 402 which is preferably fabricated from
 aluminum and is preferably 1" or less in height (h). The elongated strip
 402 is preferably the same width (w) or smaller as the width of the paper
 being fed into the printer 100. For example, if 81/2.times.11 inch paper
 is being fed into the printer with the 81/2 inch side first, the feed
 enhancer would have a maximum width w=81/2 inches and preferably not less
 than 6 inches wide.
 The feed enhancer 400 is disposed on a top surface 103a of the paper tray
 103 and positioned perpendicular to a direction in which the individual
 paper is fed into the printer 100 such that the feed enhancer 400 evens
 out the unevenness in height of the paper stack in an area of the paper
 stack that is to be fed into the printer 100.
 The feed enhancer 400 preferably also has a mounting means for mounting the
 elongated strip 402 to the top surface 103a of the paper tray 103. In the
 typical case, the top surface 103a of the paper tray 103 is ferric and the
 mounting means is a magnetic strip 404 fastened to the elongated strip 402
 whereby the elongated strip 402 is mounted to the top surface 103a of the
 paper tray 103 by a magnetic attraction between the magnetic strip 404
 attached thereto and the top surface 103a of the paper tray 103.
 Preferably, the magnetic strip 404 is fastened to the elongated strip 402
 with an adhesive. The feed enhancer of FIG. 4 is shown with a cut-out 406
 dividing the magnetic strip 404 into two sections. The cut-out allows the
 elongated strip 404 to not interfere with any raised projections or
 irregularities (not shown) on the top surface 103a of the paper tray 103
 that may correspond to the area of the cut-out thereby permitting the feed
 enhancer 400 to sit flushly on the top surface 103a on the paper tray 103.
 Referring now to FIGS. 5A-5C, therein are illustrated views corresponding
 to FIGS. 3A-3C but shown with the feed enhancer of FIG. 4 disposed on the
 top surface 103a of the paper tray 103 in which the unevenness in the
 height of the paper stacks 200, 210, 220, respectively, is evened-out in
 the area of the pick roller. It should be apparent to those skilled in the
 art, that the paper 200, 210, 220 illustrated in FIGS. 5A-5C,
 respectively, will feed properly into the printer 100, thereby reducing
 the likelihood that the paper will become jammed therein.
 Referring now to FIG. 6, a second embodiment of the feed enhancer of the
 present invention is illustrated therein. FIG. 6 illustrates a printer
 tray 600 which has a heightened portion 602 disposed at the top surface of
 the paper tray 600 and positioned perpendicular to a direction in which
 the individual paper is fed into the printer 100. The heightened portion
 602 preferably comprises a stepped portion integral with a top surface
 600a of the paper tray 600. The dimensions of the heightened portion 602
 are preferably the same as discussed previously with respect to the feed
 enhancer of FIG. 4.
 Referring now to FIG. 7, there is illustrated a third embodiment of the
 feed enhancer of the present invention in which a paper tray 700 has a
 heightened portion. The heightened portion comprises an elongated strip
 702 and an adjustment means for adjusting the height of the elongated
 strip 702 above the top surface of the paper tray.
 Referring now to FIGS. 8A, 8B, 9A, and 9B, the adjustment means preferably
 comprises a shaft 704 rotatably disposed in the paper tray 700 through
 openings 706, 708. The shaft 704 is retained in the openings 706, 708 at a
 first end with a knob 710, preferably press fit onto the shaft 704, and at
 a second end with a retaining ring 712. A cam 714 is disposed on the shaft
 704 which has an outer surface 716 which varies in distance from a central
 axis A--A of the shaft 704. A portion of the outer surface 716a is in
 contact with the elongated strip 702 through opening 718a. The knob 710 is
 preferably accessible from a front of the paper tray 700 such that a user
 can easily access the knob 710 and rotate it, thus rotating the cam 714
 about the shaft 704.
 Retaining means retains the elongated strip 702 along a path B--B
 perpendicular to the top surface 700a of the paper tray 700. Preferably
 the retaining means comprises at least two shafts 720 perpendicular to the
 top surface 700a of the paper tray 700 (in other words, parallel to the
 movement of the elongated strip 702 along axis B--B). The shafts 720 have
 a first end 720a slidingly disposed in the top surface 700a of the paper
 tray 700 and a second end 720b disposed on the elongated strip 702.
 Preferably, the second end 720b of the shafts 720 are press fit or tack
 welded into corresponding openings in the elongated strip 702 and the
 first ends 720a slide within corresponding holes on the top surface 700 of
 the paper tray 700. The first ends 720a also have a lip 720c for
 preventing the first ends 720a from coming free from their corresponding
 holes. Biasing means, such as a compression spring 722, are disposed
 around each shaft 720 for biasing the elongated strip 702 toward the top
 surface 700a of the paper tray 700. The compression springs 722 are also
 disposed between the top surface 700a of the paper tray 700 and the lip
 720c at the first ends 720a of the shafts 720.
 Referring now to FIG. 10, the third embodiment of the feed enhancer of the
 present invention also preferably includes a locking means for locking the
 elongated strip 702 at a predetermined height above the top surface 700a
 of the paper tray 700. The locking means preferably comprises a ball
 detent 800 disposed on the paper tray 700. The ball detent 800 generally
 has a threaded body which mates with a corresponding threaded hole in the
 paper tray 700. The ball detent 800 also has a ball 802 retained therein
 and biased towards the shaft 704 by a biasing means, such as a compression
 spring 804. A plurality of detents 806, which are preferably conical
 shaped cavities, are disposed around the circumference of the shaft 704.
 The detents can be disposed on the shaft 704 itself or alternatively, on a
 disk 808 retained on the shaft 704, preferably with a set screw or by
 press fitting. The ball 802 engages a corresponding detent 806a and is
 retained therein by the biasing force of the spring 804 thereby locking
 the elongated strip 702 at a height above the top surface 700a of the
 paper tray 700 corresponding to the circumferential location of the
 engaged detent 806a on the shaft 704.
 It can be appreciated that as the knob 710, shaft 704, and cam 714 attached
 thereto are rotated towards detent 806b the weight of the elongated strip
 702 and the biasing force of springs 722 will bring the elongated strip
 702 into contact with the outer surface 716 of the cam 714. The elongated
 strip 702 is at its lowest height with respect to the top surface 700a of
 the paper tray 700 when the portion of the cam 716b faces the elongated
 strip 702, as shown in FIGS. 8B and 9B. In this position, portion 716a of
 the cam 714 will retreat into opening 718b. Preferably, the paper tray 700
 includes a recess 700b, so that the elongated strip 702 is flush with the
 top surface 700a of paper tray 700.
 Obviously, the height of the elongated strip 702 above the top surface 700a
 of the paper tray 700 is variable depending upon the particular detent 806
 engaged with the ball 802. The incremental amount that the height can be
 adjusted is dependent upon the number of detents 806 disposed about the
 circumference of the shaft 704, or alternatively, the disk 808.
 In operation, the rotation of knob 710 results in the height of the
 elongated strip 702 above the top surface 700a of the paper tray 700 to
 increase or decrease depending on the distance from the central axis A--A
 of the shaft 704 to the portion of the outer surface 716 in contact with
 the elongated strip 702.
 The various embodiments of the feed enhancer of the present invention are
 illustrated as being in close proximity to the pick roller 104. However,
 it should be apparent to those skilled in the art that the feed enhancers
 can be placed at various points along the length of the paper to be fed
 into the printer without departing from the scope or spirit of the present
 invention.
 From the foregoing description, it can be appreciated by someone skilled in
 the art that the adjustment means can be utilized to offset varying
 degrees of height and unevenness in paper stacks. If the unevenness of the
 paper stack is severe, the height of the elongated strip can be increased
 as described. Alternatively, if the unevenness of the paper stack is
 minor, the height of the elongated strip can be decreased. The simplicity,
 inexpensiveness, and ease of retrofitting existing printers with the feed
 enhancer embodiments of the present invention, particularly the first
 embodiment illustrated in FIG. 4, can also be appreciated by an artisan
 skilled in the art.
 While there has been shown and described what is considered to be preferred
 embodiments of the invention, it will, of course, be understood that
 various modifications and changes in form or detail could readily be made
 without departing from the spirit of the invention. It is therefore
 intended that the invention be not limited to the exact forms described
 and illustrated, but should be constructed to cover all modifications that
 may fall within the scope of the appended claims.