Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
1999-05-28
2001-06-12
Ellis, Christopher P. (Department: 3651)
Sheet feeding or delivering
Feeding
Separators
C271S124000, C271S125000
Reexamination Certificate
active
06244587
ABSTRACT:
The present invention relates to a sheet feeding device for advancing paper sheets one by one and also to a scanner equipped with such a device.
Sheet feeders of this kind are used together with different types of paper handling machines in office environments for feeding sheets one by one for processing purposes, e.g. to read the sheets in a scanner.
One problem with known devices in this field is that they have either become too complicated to manage a single-sheet feeding function or have become relatively unreliable and often fail to feed the sheets correctly, e.g. feed several sheets at one and the same time. Machines exist that are both complicated and unreliable.
Scanning often requires paper sheets to be scanned from a sheet stack which contains paper of mutually different thick nesses. This creates further difficulties with regard to smooth uninterrupted feeding of the sheets without requiring excessively complicated arrangements to this end.
U.S. Pat. No. 4,606,535 teaches a sheet feeder constructed in accordance with known technology and including a feed opening defined between a feed belt and an inclined anvil or counter-pressure surface. The belt runs freely without being supported and can flex away under the pressure of paper sheets fed in towards the feed opening and pressed in between the anvil surface and one of the belt drive wheels. The belt takes a slight S-shape and it is difficult to control the number of sheets that shall pass through the feeder at one and the same time. The arrangement is particularly unsuitable for use when the sheets have mutually different thicknesses. Also described in U.S. Pat. No. 4,606,535 is a sheet feeder that is intended to eliminate the deficiencies of the afore described known feeder. This has been achieved with a sheet feeder in which a stack of sheets ready to be fed through the feeder are inclined relative to the horizontal plane, at an angle of about 60°. The anvil surface or the sheet holding device, or retarder, has been made resilient. In an attempt to enable sheets to be fed singly even when the thickness of the sheets vary, the sheet holding device has been provided with a large number of separate anvil or friction devices each of which is resiliently supported per se with a spring force that is mutually different for each anvil surface. The different spring constants must be accurately adapted in order for these devices to function in the manner intended and in the case of a number of embodiments, it is necessary to replace certain parts at regular intervals due to the large amount of wear on said parts.
Described in U.S. Pat. No. 3,831,928 is a feeder which is intended to reliably feed sheets one at a time and to enable sheets of mutually different thicknesses to be fed through the feeder. In this case, the belt runs between two rollers, and a further roller is provided to give support behind the belt in the infeed of the actual feed opening, whereas the remainder of the belt is unsupported. To enable sheets of different thicknesses to be fed one at a time, one side of the feed opening is defined by a pivotal sheet restraining or retarding mechanism. The large inlet angle that is formed in the infeed opening with this mechanism means that the components included in the mechanism must be adapted relative to one another with great precision in order to achieve single-sheet feeding. This applies partly to the relative distances between the components, secondly the strength of the springs that actuate the pivoted element, and thirdly the frictional coefficients of the driving surfaces. The principle of using a reciprocatingly pivoting mechanism makes the feed arrangement complicated and sensitive to disturbances. The apparatus also requires an intermittent sheet feeding sequence.
Described in U.S. Pat. No. 3,838,851 is a paper sheet feeding device in which the sheets are advanced with the aid of feed rollers. No feed belts are used. This device is not adapted to feed sheets of mutually different thicknesses.
As seen against this background, the object of the present invention is to provide a sheet feeder which although being of primarily simple construction is, nevertheless, able to feed sheets one by one even when the sheets vary in thickness.
This object has been achieved in accordance with the invention with a sheet feeder of the kind defined in the preamble of claim
1
that has the characteristic features set forth in the characterizing clause of said claim.
Because the gape, or width, of the sheet feed opening, where one side of the opening is defined by a sheet feeding belt that is supported by a rigid surface in the region of said opening, there is obtained a well-defined opening that can be adjusted so that only one sheet will be fed at a time, even when the thickness of the sheets varies.
In a preferred embodiment of the invention, either the sheet restraining or retarding device or the feed belt, or preferably both, is, are, resiliently yieldable. This facilitates adaptation of the sheet feeder to sheets of mutually different thicknesses, since an advancing sheet is able to press away one or both of these components. The elastic yieldability of said component, or components, is achieved by using a resilient material. This is a simple and reliable method of achieving the resilient yieldability.
Ideally, the feed belt and the sheet restraining or retarding device will be made of mutually the same material, which makes it easier to achieve the same resiliency in both components and provides the same coefficient of friction between the belt and a sheet as that between the restraining device and a sheet, this coefficient of friction preferably being high.
According to another preferred embodiment, the stack of sheets from which the sheets shall be fed is placed on a feed table adjacent the sheet feed opening, wherein the feed belt extends over at least half of the extension of the table in the feed direction, preferably over the full extension of the table. Because of its length, the feed belt is able to advance paper sheets of different sizes since the belt will also reach and entrain sheets of smaller formats than the other sheets and that have been placed in the “wrong” end of the sheet stack. This is highly beneficial, since when paper is fed to a scanner the sheets will often vary in size in addition to varying in thickness and quality.
Ideally, the feed opening defined between the belt and the sheet restraining or retarding device is wedge-shaped. In one preferred embodiment, the aforesaid feed opening has certain given dimensions and dimension relationships that optimize the possibility of feeding sheets of mutually different thicknesses one at a time in a problem-free manner.
The afore described embodiments and other advantageous embodiments of the inventive sheet feeder will be apparent from the Claims dependent on Claim
1
.
According to one special aspect of the invention, a scanner is equipped with an inventive sheet feeder. It is precisely with this application of the invention together with a scanner that the advantages achieved by the inventive sheet feeder find special value.
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International Search Report; International Patent Application No.: PCT/SE97/01994.
Banner & Witcoff , Ltd.
Bower Kenneth W
Ellis Christopher P.
Tekniko Design AB
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