MULTI-MODE PAPER FEEDING MECHANISM INCORPORATING A DUAL FEED RATE ROLLER SYSTEM

Abstract: A paper handling mechanism is described that can feed both cut sheets and continuous forms. This multi-mode paper handling capability is achieved by using a dual feed rate roller system. A single feed roller (30) is constructed of a compressible material and deflected by separate idler rollers (32, 36) along the input and output paths (22, 24) to produce different feed rates. By constructing the feed roller (30) out of a compressible material a high feed rate is obtained with a low feed force. Thus, precise paper feeding of both cut sheets and continuous forms is achieved with a mechanism fitting within a confined space and having small number of moving parts.

Description: The invention relates to a paper handling device for feeding cut sheets and continuous forms using a dual feed rate roller system wherein a single compressible feed roller is compressed by different amounts and thus transports the paper at different speeds along the input and output paths. In the past, computer printers were separated into two categories; one category of printer provided a high quality textual output known as a letter quality printer while the other type of printer was used primarily for data processing purposes where there was little need for a quality output. The two categories of printer employed entirely different paper handling mechanisms. The letter quality printers were designed to handle cut sheets whereas the data processing printers were set up for continuous forms. As the computer printer art has progressed, printers have become available that combine the functions of both letter quality printing as well as data processing. This has created the problem of designing a paper handling mechanism that can feed both cut sheets and continuous forms. European Patent Application EP-A-0 038 415 describes a paper feeding mechanism for cut sheets or continuous forms and comprises first means for storing blank record media, second means for storing record media having information recorded thereon, and a paper path for conveying said blank record media from said first means through the print station to said second means, said paper path comprising an input path and an output path. A disadvantage of this paper feeding mechanism is that moving the record medium along the input and output path is very complicated and liable to defects. United States Patent No. 4,569,610 describes a printer having a document transport system with alternate paths for feeding either cut sheets or continuous forms. A disadvantage of thin printer is that the continuous forms should be removed before operating in the sheet feed mode; otherwise, continuous forms are fed while in the sheet feed mode wasting paper. Another proposal is described in United States patent No. 4671686 (published 9.6.87), which describes a printer having removable paper feed modules. Different paper feeding modules have to be manually installed depending upon the type of paper to be handled, presenting an inconvenience to the operator. These disadvantages of the prior art have been overcome by the present invention. The object of this invention is to provide a paper handling mechanism that can feed continuous forms or cut sheets that is both simple to build and easy to use. This and other goals have been achieved by this invention. This invention provides an all purpose paper feeding mechanism that can handle cut sheets or continuous forms by using a dual feed rate roller system wherein a feed roller constructed of a compressible material is pressed upon by separate idler rollers with different deflections to produce different feed rates. The feed rates being related to the deflection in a non-linear relationship, thus a large deflection results in a small change in feed rate. In this manner the paper travels at a higher feed rate in the output path than in the input path. This maintains a high paper tension as the paper passes through a print station. The paper handling mechanism of the preferred embodiment is intended for use with a computer printer where the printer has means for recording information including a platen and print head. The print head and platen are disposed from one another in a predetermined spaced relationship defining a print station therebetween. The paper handling mechanism of the invention has a first means for storing blank record media, second means for storing record media having information recorded thereon and a paper path for conveying blank record media from the first means through the print station to the second means. The paper path has an input path and an output path. The mechanism also comprises a compressible feed roller in contact with first and second solid idler rollers. The first solid idler roller is disposed adjacent the input path and the second solid idler roller is disposed adjacent the output path. The first solid idler roller is directed against the compressible feed roller deforming said compressible feed roller to a reduced radius R1 and the second solid idler roller is directed against the compressible feed roller deforming said feed roller to a reduced radius R2. The reduced radius R1 is less than the reduced radius R2 so that record media travel along the output path at a feed rate greater than record media travel along the input path. In another embodiment, the improvement to a paper feed mechanism for delivering a record media to a print station and then conveying the record media to a bin means comprises a paper path having a sheet input path, a forms input path and an output path. The sheet input path has means for receiving sheets and the output path has means for transporting printed record media to the bin means for storing said printed record media. A compressible feed roller is adjacent to both the sheet input path and the output path and has an uncompressed radius R. The compressible feed roller and a first solid idler roller define an input nip therebetween for driving sheets of record media along the sheet input path to a high friction roller means downstream of said input path. The first idler roller is compressed against the compressible feed roller to reduce the uncompressed radius R to a reduced input radius R1. The first solid idler roller and the compressible feed roller of input radius R1 are in driven relationship to drive said record media along said sheet input path at a feed rate slightly greater than or equal to the feed rate of the high friction roller means. For a better understanding of the invention, reference is had to the following description taken in connection with the accompanying drawings wherein like reference numerals are used throughout to designate like parts: Figure 1 shows the dual feed rate roller system of the invention; Figure 2 is an enlarged view taken generally along the line A-A of Figure 1; Figure 3 illustrates the preferred embodiment of the dual feed rate roller system; Referring now to Figure 1, the dual feed rate roller system is there depicted. Means for recording information on record media is shown comprising a print head 1 and a platen 2. The print head can be of any type such as a wire matrix, ink jet or other suitable device for generating characters. The platen is a fixed bar constructed of aluminum or other suitable material. Print head 1 and platen 2 are disposed in a predetermined spaced relationship and between them define a print station 3. The print head and platen are part of a printer (not shown) configured for the paper handling mechanism of this invention. Separator 10 is shown with two paper bins 12 for storing blank record media and an output tray 14 for storing record media having information recorded thereon. Record media such as cut sheets, labels, envelopes or the like are transported from bins 12 to input path 22 and are returned to tray 14 along output path 24. Input path 22 and output path 24 form parts of paper path 20. Downstream of separator 10 is compressible feed roller 30 in contact with first solid idler roller 32. Feed roller 30 and idler roller 32 are disposed adjacent input path 22 and define an input nip 34 therebetween. Feed roller 30 is constructed of a micro-cellular urethane material of a low durometer as measured using the standard Shore A method. In the preferred embodiment, the compressible material of feed roller 30 has a durometer of 20 while materials having a durometer up to 40 have been shown to work. Compressible feed roller 30 has an uncompressed radius R. The action of solid idler roller 32 pressing against feed roller 30 deforms or deflects feed roller 30 to an input radius R1. After passing through input nip 34, record media travel along paper path 20 to high friction roller means 40. High friction roller means 40 comprises metering roller 42 and backup rollers 42 and 44. High friction roller means 40 accurately meters record media to print station 3. Input radius R1 is selected so that record media travel along said input path at a rate equal to or slightly greater than the rate at which record media are fed to the print station 3 by high friction roller means 40. Solid idler roller 36 is pressed against compressible feed roller 30 adjacent the output path 24 and defines an output nip 38 therebetween. The action of solid idler roller 36 against feed roller 30 deforms feed roller 30 to an output radius R2 less than or equal to uncompressed radius R. Output radius R2 is selected to be greater than input radius R1. Since feed roller 30 turns on a single shaft (not shown) at a constant angular velocity the linear velocity of record media passing through output nip 38 is greater than the linear velocity of record media passing through input nip 34. The higher feed rate at the output nip 38 is accomplished with idler roller 36 applying a lower feed force against feed roller 30 than the feed force applied by idler roller 32. The combination of high feed rate and low feed force has the synergistic effect of holding record media taut as it passes through print station 3 without disrupting the metering effect of high friction roller means 40. After passing through output nip 38, record media pass along output path 24 and are conveyed to separator 10 where they are stored in output tray 14. Referring now to Figure 2, an enlarged view of the dual feed rate rollers is shown. Solid idler rollers 32 and 36 are shown to be on fixed shafts 52 and 54 eliminating the need for spring loading. Referring to Figure 3, the preferred embodiment of the dual feed rate roller is depicted. Compressible feed roller 30 comprises a central roller 31 and supporting side rollers 33 and 35 for maintaining central roller 31 in contact with the record media (not shown) against the idler rollers 32 and 36. By minimizing the width of central roller 31, input nip 34 and output nip 38 are also minimized which reduces the drive force required to rotate shaft 50. Supporting side rollers 33 and 35 need not be constructed of the same compressible material as central roller 31, however, in the preferred embodiment they are constructed of the same material. Idler rollers 32 and 36 are constructed of acetal, nylon or other similar hard material. In the preferred embodiment, four dual feed rate rollers are arrayed on shaft 50. It is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. While the invention has been particularly shown and described with reference to the preferred embodiment, it will be understood by those skilled in the art that changes may be made without departing from the scope of the claims.

Claims: A paper feeding mechanism in combination with a printer, said printer having means for recording information on record media, the means for recording information including a platen (2) and a print head (1) for generating characters, the print head (1) being disposed in a predetermined spaced relationship from the platen (2) to define a print station (3) therebetween, the paper feeding mechanism comprises first means (12) for storing blank record media, second means (14) for storing record media having information recorded thereon, and a paper path with an input path (22) and an output path (24), for conveying said blank record media from said first means (12) through said print station (3) to said second means (14); characterized by a compressible feed roller (30) in contact with first and second solid idler rollers (32, 36), said first solid idler roller (32) being disposed adjacent said input path (22) and said second solid idler roller (36) being disposed adjacent said output path (24) where said first solid idler roller (32) is directed against said compressible feed roller (30) deforming said compressible feed roller to an effective radius R1 and said second solid idler roller (36) is directed against said compressible feed roller (30) deforming said compressible feed roller (30) to an effective radius R2 being greater than the effective radius R1 so that record media travel along said exit path (24) at a feed rate greater than said record media travel along said input path (22); a high friction roller means (40) for metering said record medium being downstream of said input path to transport said record medium along said paper path to said print station; The paper feeding mechanism of Claim 1 wherein the compressible feed roller (30) has a width less than or equal to the width of the solid idler rollers (32, 36). The paper feeding mechanism of Claim 1 to 2 wherein the compressible feed roller (30) is substantially narrower than the solid idler rollers (32, 36). The paper feeding mechanism of Claim 1 to 3 wherein the compressible feed roller further comprises a central member (31) for contacting said record media and said solid idler rollers, and side supporting means (33, 35) not in contact with said solid idler rollers (32, 36) for supporting said central member (31). The paper feeding mechanism of Claim 1 to 4 wherein the central member (31) of said compressible feed roller (30) is substantially narrower than said solid idler rollers. The paper feeding mechanism system of Claim 1 to 5 wherein the central member (31) of said compressible feed roller is less than or equal to one half the width of the solid idler rollers.

Inventors: JOHNIKIN, VIL PATRICK, RUSE, JAMES PATRICK, SCHMIDT, JOHN ANTONY, STANHOPE, DAVID WILLIAM
Applicants: INTERNATIONAL BUSINESS MACHINES CORPORATION
Application year: 1987
Main classification: B41J11
IPC codes: B41J13, B41J11, B65H20, B41J15