GB2363602A - Feed singulation device - Google Patents

Abstract

A feed singulation device has a feeding means 1, preferably a roller 4, for feeding a first sheet and a means for retarding any adjacent sheet. The retarding mean 2 has a pivotally mounted and unidirectional rotatable member, preferably a high friction belt 7. In operation, the retarding means contacts the adjacent sheet and is pivoted, causing the member to be indexed in the direction of rotation. The belt 7 may pass over rollers 5,6, which are connected by an arm 8. The retarding means may be biassed towards the sheets by a spring 10.

Description

2363602 FEED SINGULATION DEVICE The present invention relates to a feed

singulation device.

There are many instances where documents, labels, envelopes, sheets of paper and the like are required to be fed singularly from a stack.

Examples are evident all around in such equipment as photocopiers, computer printers, envelope printers, document processing devices and so on It is important in many of these situations that only single documents are fed from the stack Multiple feeds may result in wasted material, jams or out-of-sequence items.

There are many different ways in which singulation may be achieved.

The choice of method for a particular piece of equipment is a compromise between the effectiveness of the method and the cost of implementing that method Conventionally, the higher duty the equipment, the more expensive it is and the more effective the singulation device which is justified.

There is advantage, therefore, if a novel design allows an effective, but previously relatively expensive, method to be used on a wider range of equipment due to being able to incorporate it without excessive build costs.

Devices that feed paper or similar media often use rollers or belts covered with a high friction material in order to pull a piece of paper or similar media from a stack It is often important to make sure that only a single piece is taken and various measures are employed in order to ensure that this is the case.

A common method is to use a further friction device opposing the motion of the feed belts or rollers Should a second, or multiple, piece be pulled from the stack along with the first piece, the opposing friction device holds (or 'retards') the other pieces back while the first is pulled out.

This retard device can take many forms On the simplest level, a block of material having a level of friction less than that of the feed belts or rollers, but greater than the friction between the media pieces can be provided Examples of this approach are described in U S 5,401,013 and US 5,326,181 Such materials are subject to wear due to the large amount of rubbing between the media and the retard device The retard block can be spring loaded to compensate for the wear to some extent This has the additional benefit of being able to accommodate different thicknesses of the medium being fed.

Higher duty systems require more complex and costly solutions in order to extend the reliable life of the retard device These systems often use an opposing set of belts or rollers, sprung towards the feed belts or rollers The opposing belts or rollers are again covered with a material having a level of friction less than that of the feed belts or rollers but greater than the friction between the media pieces These belts or rollers are driven by a separate drive system in a reverse direction to the feed belts or rollers.

This contra-rotation aids the singulation of the media elements and extends the life of the retard system considerably due to the significantly larger area of material available.

Whilst the contra-rotating retard system has a significant functional advantage over the static block approach, it also carries a costly overhead due to the need for a separate drive system to provide the contra-rotary motion.

A device which can combine the functional advantage of the contrarotating retard along with the mechanical simplicity of the sprung block approach would benefit many feeding systems.

According to the present invention, there is provided a feed singulatlon device for feeding individual sheets from a stack of sheets, comprising means for feeding a first sheet from the stack and means for retarding the feed of any next adjacent sheet carried along with the first sheet the means for retarding comprising a pivotally mounted unidirectional rotatable member which, in operation, contacts the adjacent sheet and is pivoted thereby, the pivotal movement causing the member to be indexed in the direction of rotation.

In a preferred embodiment of the invention the means for feeding comprise a roller drive driving one or more feed belts The unidirectional rotatable member comprises a roller to which a clutch is attached The clutch operates to permit rotation of the member in one direction only The means for retarding comprises a further unidirectional rotatable members.

This also comprises a roller to which a clutch is attached and which operates to permit rotation of the roller in one direction only The two unidirectional rotatable members support a retard belt The belt and member are supported on an arm which is mounted for pivotable movement about the axis of one of the members The retard belt has a coefficient of friction which is less than that of the feed belt but more than that between adjacent sheets being fed The arm is spring loaded to urge it towards the means for feeding The arm may adopt a leading or a trailing position with respect to the means for feeding In operation, the arm is pushed up by the action of sheets advanced by the means for feeding and then urged back by the spring loading after the first sheet has passed through This return action causes the retard belt to index in a direction to resist forward feed movement of other sheets from the stack This action is achieved without the provision of a drive for the means for retarding.

In order that the invention may be more clearly understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 diagrammatically shows a side elevational view of a feed singulation device, and Figure 2 diagrammatically shows a partial plan view of the device of figure 1.

Referring to the drawings, the device comprises means for feeding indicated generally by the reference numeral 1 and means for retarding indicated generally by the reference numeral 2 The means for feeding 1 comprises high friction feed belts 3 supported on and driven by a feed roller 4 In operation the feed belts 3 and feed roller 4 move in the clockwise direction.

The means for retarding comprises primary and secondary rollers 5 and 6 around which a retard belt 7 or a number of retard belts 7 are fitted.

The primary roller 5 is fixed to an arm 8 mounted for pivotal movement about a fixed shaft 9, which also forms the axis of rotation of the secondary roller 6 Both rollers 5 and 6 are fitted with single direction clutches Single direction clutches are commercially available devices which permit rotational motion in one direction, but prevent it in another In this case, the clutches are fitted in such a way as to allow motion only in the direction opposing the feed direction (clockwise in Figure 1) The arm 8 is sprung by means of a compression spring 10 constrained to act between a fixed point 11 and a point 12 on the arm 8 to apply pressure towards the feed belt 3.

The device is set up to feed single envelopes from a stack of envelopes 13 The stack of envelopes 13 is supported on the feed belts 3.

When the drive of the belts 3 is engaged, the stack is advanced towards the means for retarding 2 The lowest envelope 14 only is in contact with the high friction feed belts 3 which have a higher friction level than the retard belt 7 Thus the lowest envelope 14 is driven under the retard belts, lifting them against the action of the spring 10 The other envelopes are held back by the retard belts 7 as the friction between the retard belts and the envelopes exceeds that between envelopes.

The lifting action causes the arm 8 to rotate slightly in a clockwise direction This causes the secondary roller 6 to rotate clockwise on the fixed shaft 9 The clutch fitted to the primary roller 5 holds any tendency for anticlockwise motion which may result from the motion of the envelope under the primary roller 5 As the end of the envelope 14 clears the feed roll 4, the spring 5 urges the arm 1 back towards the feed roller 4, the arm 1 rotating slightly anticlockwise As the secondary roller 4 cannot rotate anticlockwise due to the clutch fitted to this roller, the primary roller 5 rotates clockwise In this way, the slight raising and lowering of the arm 8 results in incremental movement of the retard belt 7 in a clockwise direction Thus the ideal contra-rotary motion is achieved without use of a separate drive.

For optimum performance, the thickness of the medium being fed should allow for a rotation of the arm of at least about Y 2 o Should a thin medium be fed, this may not provide sufficient vertical movement for that amount of arm rotation In this case, the feed roller 4 may be provided with a slightly eccentric motion to provide the vertical arm movement necessary.

Because the means for retarding is spring loaded, there may be no need to adjust for envelopes of differing thicknesses Empty envelopes up to envelopes over 3 mm thick may be fed on a single setting, the setting being the distance from the feed roller 4 to the axis of the arm 8 This will cover the majority of requirements When adjustment is necessary, it is relatively easy to make Also, because of the contra-rotational nature of the means for retarding, wear is spread over a much larger area Readjustment or replacement of retard belts is therefore required less frequently.

The embodiment is described in relation to a feeder within an envelope printer Although particularly effective in this application, it is not restricted to this type of feeder and should be effective in feeders of other media Other possible geometries and layouts than that described are possible.

It will be appreciated that the above embodiment has been described by way of example only and that many variations are possible without departing from the scope of the invention For example, the described layout features a leading linkage for the arm A trailing link arm would also be similarly effective.

Claims (12)

1 A feed singulation device for feeding individual sheets from a stack of sheets, comprising means for feeding a first sheet from the stack and means for retarding the feed of any next adjacent sheet carried along with the first sheet the means for retarding comprising a pivotally mounted unidirectional rotatable member which, in operation, contacts the adjacent sheet and is pivoted thereby, the pivotal movement causing the member to be indexed in the direction of rotation.

2 A feed singulation device as claimed in claim 1, in which the means for feeding comprise a roller drive driving one or more feed belts.

3 A feed singulation device as claimed in claim 1 or 2, in which the unidirectional member comprises a roller to which a clutch is attached.

4 A feed singulation device as claimed in claim 3, in which the clutch operates to permit rotation of the member in one direction only.

A feed singulation device as claimed in any preceding claim, in which the means for retarding comprises a further unidirectional rotatable member.

6 A feed singulation device as claimed in claim 5, in which the further unidirectional rotatable member comprises a roller to which a clutch is attached and which operates to permit rotation of the roller in one direction only.

7 A feed singulation device as claimed in claim 6, in which the two unidirectional rotatable members support a retard belt.

8 A feed singulation device as claimed in claim 7, in which the belt and members are supported on an arm which is mounted for pivotable movement about the axis of one of the members.

9 A feed singulation device as claimed in claim 7 or 8, when appendant to claim 2, in which the retard belt has a coefficient of friction which is less than that of the feed belt but more than that between adjacent sheets being fed.

A feed singulation device as claimed in claim 8 or claim 9 when appendant to claim 8, in which the arm is spring loaded to urge it towards the means for feeding.

11 A feed singulation device as claimed in claim 10, in which the arm is pushed up by the action of sheets advanced by the means for feeding and then urged back by the spring loading after the first sheet has passed through the return action causing the retard belt to index in a direction to resist forward feed movement of other sheets from the stack.

12 A feed singulation device substantially as hereinbefore described with reference to the accompanying drawings.