PAPER-HANDLING MECHANISM FOR A PRINTER

Abstract: A printer is provided with a controllable bail (32) located between a print station (22) and a downstream paper tear-off station (34). Upon a occurrence of the first control signal, a printed portion of the paper is advanced to a desired tear-off position adjacent the tear-off station (34). Thereafter (after a predetermined time delay or after operator switch actuation), the paper is retracted. The intermediately located bail (32) is released at least after the leading edge of the paper is retracted thereunder and until sufficient paper is again advanced (e.g. during new printing operations) to ensure that paper is again located between the printing platen (20) and the bail (32) before the bail is re-engaged.

Description: This application relates generally to printers of the type commonly used as output devices in computer control data processing systems and the like. Computer driven printers are now common place. Typically, individual sheets or continuous form paper is fed past a platen at a printing station where desired visual indicia are transferred to the paper surface (e.g. via an ink ribbon, dot matrix print head, etc.). It is also common to use a paper bail located just downstream of the print station so as to maintain the paper in contact with the platen surface throughout the printing operation before the printed portion of the paper completely exits from the printer. It is also typical to include a tear-off station so that a printed page or other portion of the paper may be neatly and conveniently torn off (or separated at a line of pre-formed perforations or the like). In some printers, the tear-off station is coincident with the bail. In other printers the tear-off station may be located a substantial distance downstream from the bail member. Typically, in prior art arrangements, the bail is manually operated and the tear-off function is manually achieved by manual manipulation of the platen, for example, so as to advance the paper as desired to the tear-off position and/or to retract the paper after tear-off to a desired new line of print position. DE3306083 discloses a device which controls the feeding of paper in a printer where the paper is in the form of a continuous roll. In this device, when a command for a new page is generated, a central processing unit initiates a tear-off line printing operation. After printing the tear-off line, the paper is advanced until the printed tear-off line reaches a tear-off position. The operator then tears off the printed sheet. The paper is retracted to the first print line position of a new page in response to a print signal being received at the input buffer of the device. Thus, the paper retract operation is dependent upon available symbols to be printed. The present invention includes a power driven bail member which, in conjunction with the paper drive mechanism, is programmed so as to automatically facilitate the paper tear-off function in an efficient and advantageous manner. In the exemplary embodiment the novel tear-off function is initiated by a first control signal which may, for example, be generated by an operator manipulated switch. Alternatively, the first control signal might be generated by the printer control circuits when an end-of-printed-document signal or the like is generated. In response to this first control signal, the paper is advanced so that the last printed line is moved downstream of the tear-off station leaving the paper in a position where it can be immediately severed and used by an operator. Thereafter, a second control signal is generated in response to some predetermined time lapse from the first control signal and/or in response to manual operator switch actuation so as to retract the new leading edge of the remaining paper into a desired new first print line position at the printing station. Typically, such retraction will temporarily cause the leading edge of the paper to pass upstream of the bail. Accordingly, a power-driven bail is provided so that it may be released at least after such paper retraction until the paper is again advanced (e.g. during subsequent printing operations) to the point where paper is again disposed between the bail position and the platen whereupon the bail again may be actuated. In the preferred exemplary embodiment, a more complex bail actuation/de-actuation sequence may also be employed so as to even further facilitate the tear-off function. In this more complex sequence, the paper bail is additionally released during paper advancement to the tear-off station and then re-applied to more firmly hold the paper in position during the tear-off operation. Subsequently, the bail bias may also be released again during retraction of the paper to the new desired print line position. Of course, if the new leading edge of the paper is not retracted upstream of the bail, then the bail bias may immediately be applied once the paper is in the new print line position. Otherwise, the bail bias should remain deactivated until sufficient new printing has. occurred to again pass paper between the bail and the platen. These as well as other objects and advantages of this invention will be more completely understood and appreciated by careful study of the following detailed description of the presently preferred exemplary embodiment taken in conjunction with the accompanying drawings of which: IN THE DRAWINGS: FIGURE 1 is a schematic cross-sectional view of an examplary embodiment of a printer constructed in accordance with this invention; FIGURE 2 is a schematic diagram of the electrical control circuits for the examplary embodiment of Figure 1; FIGURE 3 is a view of an examplary embodiment of a printer in accordance with this invention; and FIGURE 4 is a flow chart of a suitable tear-off Control function program sequence which may be embodied in the microprocessor-based printer Controller of the exemplary embodiment. An exemplary embodiment of the printer 10 is depicted at FIGURES 1-2. It generally includes an upper housing member 12 and a lower housing member 14 hingedly connected at 16 near the lower rear portion of the lower housing member 14. A rear portion of the housings include an angular configuration at 18 so as to accommodate a rotational opening motion to the open position. As will be observed, in the open position the rear relatively angled portions of the housings 12, 14 fit in abutting relationship. However, rather than to place the rotational connection near the parting line between the upper and lower housings (e.g. near the apex of the angled section 18), the preferred embodiment places the rotatable connection 16 at a lower rear location within the lower housing member 14 thus providing a rearward "over center" type of movement which provides an even wider open mouth in the paper loading access position. The printer 10 includes the usual rotatable platen 20 which has a print station 22 located at its front side where printed indicia are imparted to a paper surface carried by the front side of the platen. Suitable guides 24, 26 may be conventionally provided for directing individual form sheets 28 input through an entrance slot 30 into engagement with the rear side of the platen 20 such that, upon rotation of the platen, the paper is directed around and past print station 22, under paper bail 32 and out paper exit slot 34. Printing may be performed at print station 22 by any convention printing mechanism such as, for example, a conventional driven print ribbon 36 and a dot matrix print head 38 which is driven transversely along carriage 40 by conventional carriage drive mechanism 42. A continuous form tractor drive 44 (of conventional design) is mounted below the platen 20 and includes suitable paper guides 46, 48 so as to pull continuous form fan fold paper 50 or the like through a paper entrance slot 52 in the bottom of the lower housing member 14 and upwardly into engagement with the front side of platen 20 past the print station 22, under bail 32 and through paper exit slot 34. One or more conventional motors may be utilized for individually driving the print head along the carriage, the ribbon with respect to the print head, the platen 20 and the tractor drive 44. In the schematic depiction of FIGURE 1, a single motor 54 has been schematically depicted for simplicity. In the exemplary embodiment, all of the mechanically driven components, including the tractor drive 44 are carried by the upper housing member 12. The electronic printer controller may be housed where convenient. As depicted in FIGURE 1, the printer controller might comprise two printer circuit boards, one of which (board number 1) is mounted in the lower housing member 14 while the other ( printer control board number 2) may be mounted in the upper housing member 12. Multiconductor cabling 56 may then be routed around the interior edges of the printer housings and in proximity with the rotational point 16 so as to interconnect the printer controller boards, the various drive motors 54, wire driving electromagnets and the print head 38, the carriage drive, etc. A transparent section 60 is also preferably provided so as to permit viewing of the print station area (or at least a view of the line that has previously been printed) before the paper exits from slot 34. In addition, a sharp edge 62 may be provided in the transparent member 60 along the front of the exit slot 34 so as to provide a convenient tear off position for paper that has previously been printed (this is especially useful for the continuous form paper 50 as will be appreciated). As schematically depicted in FIGURE 2, the printer controller 58a, 58b may be connected to a convenience switch 64 that is actuated to a predetermined opened or closed position whenever the hinged housing members 12, 14 are opened such that the printer controller can be conditioned to automatically cease any printing operation whenever the housing members are rotated away from the closed position. One possible location for such a switch 64 is also depicted schematically in FIGURE 1. The printer controller may also accept plug in font control modules 66 so as to permit convenient operator control of the printing font. The usual operator control switch panel 68 is also provided and interconnected via multiconductor cabling 56 to the appropriate printer control boards. A manual drive knob 70 may also be provided for the platen 20. The embodiment includes an electro-mechanical bail drive mechanism, for example a motor, electromagnetic actuator, etc (not shown but of conventional form), which is capable of physically moving the bail 32 into a pressure biased position against the platen 20 or away there from so as to permit paper to freely pass between the bail and the platen. In the exemplary embodiment the bail is energized into engagement with the platen so as to engage an intermediate paper whenever there is paper present at that location and either (a) a printing operation is underway or (b) the paper is in position for operator tear-off. Alternatively, the bail may be left in engagement with the paper at all times except in the event that the new leading edge of the paper (i.e. after a tear-off function has occurred) is retracted sufficiently upstream as to temporarily result in an absence of paper between the bail and the platen 20. In this later event, the bail drive is deactivated so as to retract the bail and permit free paper movements thereunder during subsequent printing/paper advancement times until paper once again is present between the bail 32 and the platen 20 whereupon the bail drive member may again be actuated. As shown in FIGURE 2, there may be a significant distance between the paper bail 32 and the paper tear-off station 62 (e.g. it might be as much as six lines or so of print positions). The distance between the bail 32 and the tear-off station 62 will, of course, vary from one embodiment to the next in accordance with the printer design criteria. The printer controller 58A, 58B which drives all of the printer mechanisms including the bail drive , is in the exemplary embodiment a microprocessor-based device. Insofar as the present invention is concerned, the microprocessor controller may be of conventional design except for the tear-off function which may be embodied in a suitable computer program of the type depicted in the flow chart of FIGURE 4. As will be appreciated, this tear-off function program may be embodied as a separate sub-routine or embodied directly within other printer controller program routines. Entry to the tear-off function 300 may actually occur as a result of an interrupt signal or the like which may occur at step 302 as a result of depression of an operator control switch (e.g. one of switches 68 on the control panel). Alternatively, an end of document control signal or the like may suffice for creation of a first control signal which causes entry to the tear-off function routine. In the exemplary embodiment, the paper bail is released at step 304 and the paper is thereafter advanced at step 306 to a desired tear-off position via the conventional paper drive mechanism. Then, the paper bail bias is re-applied at step 308 and time is provided for an operator manual tear-off function (or automatic tear-off, cutting, etc.) at step 310 either by a predetermined time delay 312 or until depression of a second switch at step 314 before progressing further in a tear-off function flow Chart of FIGURE 4. At the conclusion of the actual tear-off time (as defined by the initiation of a second control signal via steps 312 or 314), the bail bias is again released at step 316 and the new leading edge of the paper is retracted at step 318 to a desired new print position. In the exemplary embodiment, there is sufficient distance between the bail and the tear-off station that the new leading edge is actually retracted past the bail. Accordingly, approximately six lines of new print is permitted at step 320 before paper is again located under the bail and the bail bias may again be reapplied at step 322 before the tear-off function is Completed at exit point 324. As will be appreciated, if six lines of normal printing operations are to occur at step 320 before the bail bias is re-applied at step 322, then 322 may actually be embodied within the normal print routine in conjunction with suitable data flags or the like indicating that a new printing operation has been initiated just subsequent to a tear-off function so that step 322 is to be performed after six lines worth of paper advancement have occurred. Since paper may normally be driven past the biased bail position, one may alternately by-pass the bail release steps as indicated by dotted lines 326, 328 and 330. However, if the retraction step 318 actually withdraws the new leading edge of the paper upstream of the bail location, then the bail bias must be released at least sufficiently to permit the new leading edge to again advance between the bail and the platen before regular bail bias is re-applied. While only one exemplary embodiment of this invention has been described in detail, those skilled in the art will recognize that there are many possible modifications and variations which may be made in this exemplary embodiment while yet remaining within the scope of the appended claims.

Claims: A printer for printing on paper at a printing station and including a downstream paper tear-off position (34), said printer comprising: A. means for generating a first control signal and means for generating a second control signal; B. means for automatically advancing the paper from a print line position (22) to the tear-off position (34) in response to said first control signal, and C. means to subsequently automatically retract the paper to the print line position (22) in response to said second control signal, characterised in that the printer includes time delay means for indicating the expiry of a predetermined delay from the said first control signal, and an operator actuable switch and wherein the means for generating the second control signal is responsive to either or both of the said time delay means, or the operator actuable switch. A printer as claimed in Claim 1 having a platen (20) at said printing station and comprising paper bail means (32) normally biasing the paper toward said platen (20) during printing and responsive to said second control signal to disable said bias after said retraction until after subsequent advancement of the paper causes it to again pass under said bail means (32). A printer as claimed in Claim 2 wherein the said paper bail means (32) is electrically driven, and is disposed adjacent said platen and between said printing line position (22), and said paper tear-off station (34) and including means (58 a , 58 b ) for releasing said bail (32) from engagement with the paper at least after reverse driving of the paper from said tear-off station when there is no paper situated thereunder and for driving said bail (32) into paper engagement at other times when paper is present thereunder during printing operations. A printer as claimed in Claim 3 wherein said means for driving said bail (32) into paper engagement is also activated after paper advancement to said tear-off position. A printer as claimed in any one of the preceding claims including an operable actuable switch for generating the said first control signal. A printer claimed in any one of the preceding claims wherein said operator actuable switch is switch (68) on a printer control panel. A printer as claimed in any one of the preceding claims, including a structural edge (62) at the tear-off position against which paper may be conveniently torn. A printer as claimed in any one of the preceding claims, including means for suspending printing during the periods of said paper advancement and retraction until said paper is available for printing at said print line position. A method of controlling paper movement, to and from a tear-off position in a printer, comprising: initiating a first control signal to advance a predetermined portion of said paper from a print line position to the tear-off position, subsequently initiating a second control signal to retract a second predetermined portion of said paper to the print line position, characterised in that the printer includes time delay means for indicating the expiry of a predetermined delay from the said first control signal, in that the second control signal is produced in response to either or both of an operator actuable switch and the expiry of the said predetermined time delay. A method as claimed in Claim 9 further comprising: causing the temporary release of a paper bail at least after said retraction when paper is no longer disposed between the bail and a print platen. A method claimed as in Claim 9 or Claim 10 wherein said second control signal is automatically initiated after a predetermined period of time elapses after occurrence of said first control signal. A method as claimed in Claim 9 or Claim 10 wherein said second control signal is initiated by depressing a switch on a printer control panel (68a).

Inventors: WARD, DAVID O., ZAJAC, THEODORE S, JR.
Applicants: GENICOM CORPORATION
Application year: 1986
Main classification: B41J13
IPC codes: B41J11, B41J13