SINGLER FOR FLAT ARTICLES SUCH AS DOCUMENTS

Abstract: A documents singler which takes documents (4) from a stack and conveys them one by one to a user station via document retaining means (13). It includes a first conveyor belt (5) which has a document driving surface (8) facing the retaining means. The latter include a second belt (12) of which the external surface (11) is driven by the driving surface (8) and of which the inner surface (17) faces a braking surface (18). When more than one document try to pass between the first and the second belts, the one driven by the first belt exits first from the retaining means, the other or others being retained by the second belt which is no more driven by the first belt and is stopped by the braking surface against which it is pressed.

Description: SINGLER FOR FLAT ARTICLES SUCH AS DOCUMENTS The present invention relates to a singler for flat articles such as documents to take them from a stack and convey them one by one to a user station* including a driving conveyor belt and document retaining means, said conveyor belt having a driving surface facing said stack and said document retaining means which include a brake member having a braking surface* said conveyor belt being able by its driving surface to take a document from said stack and convey it to said document retaining means of which the braking surface cooperates with said driving surface to prevent one or more additional documents taken from said stack together with said document to be si ultaneously conveyed to said user station. Such a document singler is already known, e.g. from the German patent application No 2 309 756. In this application, the document retaining means are solely constituted by the brake member of which the braking surface is permanently urged by means of a spring against the driving surface of the conveyor belt. When only one document is fed to the document retaining means* the frictional force then exerted by the braking surface on this document* e.g. a mailing envelope, must be sufficiently low in order not to hinder the transfer of this document to the user station. On the contrary, when more documents are fed together to the document retaining means, the frictional force exerted by the braking surface on the additional documents must be sufficiently high to retain this or these additional documents. In other words, the choice of the braking surface is always a compromise so that it is very difficult with the known document singler to realize an efficient singling operation, especially when the documents processed may have thicknesses varying within a large range. Another drawback of this known singler is that, due to the permanent frictional contact between the driving surface and the braking surface* these surfaces are subjected to an intensive wear leading to a rapid reduction of their efficiency. An object of the present invention is to provide a document singler of the above type but which has an improved efficiency and wherein the choice of the braking surface is not subject to a compromise. According to the invention this object is achieved due to the fact that said document retaining means also include a second conveyor belt running between the first mentioned conveyor belt and said braking surface* said second conveyor belt having a first surface through which it is driven by the motion of said first conveyor belt via said driving surface and a second surface in contact with said braking surface, the documents being conveyed between said first conveyor belt and said second conveyor belt which is braked by said braking surface when said additional documents are fed to said document retaining means so as to prevent them from being supplied to said user station. In this way, the second conveyor belt isolates the driving surface from the braking surface so that none of them adversely affects the efficiency of the other and that each of them can give its optimum driving and braking characteristics respectively independently from the other. Because the second conveyor belt is driven by the first conveyor belt either directly or via one or more documents* there is never a friction between the driving surface and the first surface so that these surfaces are not subjected to wear. Another characteristic feature of the present invention is that the value of the braking effect produced on said second conveyor belt by said braking surface is such that said second conveyor belt is substantially stopped when at least two documents are fed together to said document retaining means. In this way* the additional documents are stopped by the second conveyor belt until the document facing the driving surface of the first conveyor belt has been fed to the user station. An additional characteristic feature of the present invention is that the position of said braking surface is stationary with respect to the path followed by said first and second conveyor belts. In this way* the wanted braking effect may be adjusted once and for all by accurately positioning the brake member and more particularly its braking surface with respect to the second surface of the second conveyor belt. Still another characteristic feature of the present invention is that the coefficient of friction between said driving surface and a document has a value substantially equal to that of the coefficient of friction between said first surface and a document. Furthermore* the coefficient of friction between two documents has a value lower than that of said coefficient of friction between said driving surface and a document. Finally, the coefficient of friction between said second surface and said braking surface has a value between that of said coefficient of friction between two documents and that of said coefficient of friction between said driving surface and a document. In this way, when for instance two documents are fed - <_ - together to the document retaining means* they are respectively conveyed at the displacement speed of the driving surface and at the displacement speed of the first surface which faces them. Since the second conveyor belt is then driven by the first conveyor belt via these documents and is braked by the braking surface because of the additional document fed to the document retaining means* the speed of this second conveyor belt becomes lower than that of the first conveyor belt. As a result* the two documents slide over each other and the one facing the driving surface exits first from the document retaining means . The above mentioned and other objects and features of the invention will become more apparent and the invention itself will be best understood by referring to the following description of an embodiment taken in conjunction with the accompanying drawing which shows a document singler according to the invention. The document singler shown in the drawing is intended to take documents * for instance envelopes of mail* from a stack and to transmit them one by one to a user station. It is provided with document retaining means located between the stack and the user station and able to single the documents when more than one are taken together from the stack. This singler includes a base plate 1 which carries two flat positioning belts 2 and 3 able to transport a stack of documents ' vertically arranged on their edge. The base plate 1 is sligthly inclined towards a first edgewise positioned conveyor belt 5 carried by a roller 6 which is driven by an electrical motor (not shown) and a free running roller 7. The external or driving surface 8 of this conveyor belt 5 faces the documents 4 of the stack at a location generally indicated by number 9 where it is able to take the documents one by one from this stack. The first conveyor belt 5 then convey the documents to a user station (not shown) via another location generally indicated by number 10 and where its driving surface 8 faces the external or first surface 11 of a second conveyor belt 12 forming part of the document retaining means generally indicated by number 13. This second conveyor belt 12* also edgewise positioned* is carried by three free running rollers 14* 15 and 16 which are so arranged that the external surface 11 of this belt 12 faces the driving surface 8 of the belt 5 and is in contact therewith over a length of about 1 centimeter. At the same location and over this same length* the inner or second surface 17 of the conveyor belt 12 faces and is in contact with a braking surface 18 generally in metal and rigidly mounted on a L-shaped bracket 19 fixed* in an adjustable manner* to the frame (not shown) of the document singler. The driving surface 8 of the first conveyor belt 5 as well as the external surface 11 of the second conveyor belt 12 are covered with a coating of which the coefficient of friction with respect to the documents to be conveyed has a relative value equal to 1* i .e. that no sliding occurs neither between these surfaces nor between each of these surfaces and a document. Moreover, the coefficient of friction of the inner surface 17 of the conveyor belt 12 with respect to the braking surface 18 has a relative value approx i mat i vely equal to 0.6 whilst the relative value of the coefficient of friction between two documents is approx i mat i vely equal to 0.3. When no document is conveyed* the conveyor belt 5 drives the conveyor belt 12 at the location 10 by the permanent contact between the driving surface 8 and the external surface 11. When a document -_ is taken from the stack by the driving surface 8 and is conveyed to the document retaining means 13, this document is routed between the conveyor belts 5 and 12 at the location 10. In this case* the conveyor belt 12 is still driven by the motion of the conveyor belt 5 but via the conveyed document instead of directly. Since the coefficients of friction between each of these two conveyor belts and a document are both equal to 1* the conveyor belt 12 also moves at the same speed as the conveyor belt 5. In both these cases* without or with a document conveyed* the two conveyor belts 5 and 12 are running at a same speed and are therefore not subjected to any wear. Furthermore, the position of the braking surface 18 with respect to the inner surface 17 of the conveyor belt 12 is so chosen that in the two above cases the motion of this latter belt 12 is not hindered by the friction between these surfaces. When two documents are simultaneously taken from the stack and fed together to the document retaining means 13, the force exerted thereon at the location 10 by the conveyor belts 5 and 12 causes the corresponding document facing one of these belts to be displaced at the same speed as this belt. Due to the thickness of these documents * the conveyor belt 12 is pressed against the braking surface 18 and because of the friction between the braking surface 18 and the inner surface 17 of the belt 12 the latter is braked by this braking surface 18. The document facing the external surface 11 is then braked and thus delayed with respect to the document facing the driving surface 8 and conveyed thereby. In practice the position of the braking surface 18 is adjusted in such a way that the conveyor belt 12 is stopped as soon as a second document enters in the document retaining means 13. A relative movement is thus produced between the documents which slide along each other but not with respect to their corresponding belt 5 or 12. Furthermore* since the driving surface 8 of the conveyor belt 5 is then no more in contact with the external surface 11 of the conveyor belt 12* the coating of these surfaces is not subjected to wear by the relative movement of the two documents. The only wears are produced on the rear or inner surface 17 of the conveyor belt 12* on the braking surface 18 and between the documents. These wears are negligible and do not directly affect the efficiency of the document singler. When more than two documents are fed together to the document retaining means 13, the conveyor belt 12 is pushed against the braking surface 18 and also stopped thereby. As a consequence* the document facing the driving surface 8 is fed first to the user station whereas all the other documents are retained by the external surface 11 of the belt 12. When the first document exits from the document retaining means 13* the second document then facing the driving surface 8 exits to the user station and so on until only one document remains in the document retaining means 13. Then, the conveyor belt 12 again starts running at the same speed as the conveyor belt 5 and the last document is transferred to the user station. While the principles of the invention have been described above in connection with specific apparatus* it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of the invention.

Claims: CLAIMS 1. Singler for flat articles such as documents (4) to take them from a stack and convey them one by one to a user station * including a driving conveyor belt (5) and document retaining means (13)* said conveyor belt having a driving surface (8) facing said stack and said document retaining means which include a brake member (19) having a braking surface (18), said conveyor belt being able by its driving surface to take a document from said stack and convey it to said document retaining means of which the braking surface cooperates with said driving surface to prevent one or more additional documents taken from said stack together with said document to be simultaneously conveyed to said user station * characterized in that said document retaining means (13) also include a second conveyor belt (12) running between the first mentioned conveyor belt (5) and said braking surface (18)* said second conveyor belt having a first surface (11) through which it is driven by the motion of said first conveyor belt via said driving surface (8) and a second surface (17) in contact with said braking surface* the documents (4) being conveyed between said first conveyor belt and said second conveyor belt which is braked by said braking surface when said additional documents are fed to said document retaining means so as to prevent them from being supplied to said user station. 2. Document singler according to claim 1, characterized in that the value of the braking effect produced on said second conveyor belt (12) by said braking surface (18) increases with the number of documents (4) fed together to said document retaining means (13). 3. Document singler according to claim 1* characte ized in that the value of the braking effect produced on said second conveyor belt (12) by said braking surface (18) is such that said second conveyor belt is substantially stopped when at least two documents (4) are fed together to said document retaining means (13). 4. Document singler according to claim 1, characterized in that the position of said braking surface (18) is stationary with respect to the path followed by said first (5) and second (12) conveyor belts. 5. Document singler according to claim 1* characterized in that the coefficient of friction between said driving surface (8) and a document (4) has a value substantially equal to that of the coefficient of friction between said first surface (11) and a document. 6. Document singler according to claim 5* characterized in that the coefficient of friction between two documents has a value lower than that of said coefficient of friction between said driving surface (8) and a document (4). 7. Document singler according to claim 6, characterized in that the coefficient of friction between said second surface (17) and said braking surface (18) has a value between that of said coefficient of friction between two documents and that of said coefficient of friction between said driving surface (8) and a document (<.). 8. Document singler according to claim 1* characterized in that said second surface (17) is constituted by the inner or rear side of said second conveyor belt (12).

Inventors: DEBACKERE RAYMOND GILBERT REMI, MOENS LUDO CAROLUS MONIQUE, DEBACKERE, RAYMOND, GILBERT, REMIGIUS, DOMINICUS, MOENS, LUDO, CAROLUS, MONIQUE
Applicants: BELL TELEPHONE MFG, BELL TELEPHONE MANUFACTURING COMPANY NAAMLOZE VENN
Application year: 1988
Main classification: B65H3
IPC codes: B65H3