GB2202798A

GB2202798A - Ink-ribbon feeding strategies

Info

Publication number: GB2202798A
Application number: GB08804691A
Authority: GB
Inventors: Jr Thomas J Norman; Jr James R Ingram; Joel Yo-Sheng Lin
Original assignee: Banctec Inc
Current assignee: Banctec Inc
Priority date: 1987-03-02
Filing date: 1988-02-29
Publication date: 1988-10-05
Anticipated expiration: 2008-02-29
Also published as: AU1255088A; FR2611591A1; GB2202798B; GB8804691D0; CA1310860C; FR2611591B1; AU606134B2

Abstract

In a printing apparatus wherein a document to be printed upon and a single strike ink ribbon are moved conjointly with respect to a printing station, the ribbon is reversed between successive documents so as to position the first strike of a succeeding document adjacent the last strike of the preceding document, thereby eliminating unused portions of ribbon. <IMAGE>

Description

RIBBON CONTROL MECESNISM Technical Field This Thls application relates to ribbon control mechanisms for printing devices, and more particularly to a ribbon control Iilmechanlsm including reversible drive apparatus for a printing device using a single-strike ribbon.

Background Art It is known in the art to print across a document in horizontal motion, sometimes referred to as horizontal "on the fly" printing. Printing "on the fly" may be accomplished by proving a number of fixed hammers and a corresponding set of fixed character dies, through which a document and an ink ribbon are transported in unison while the hammers are activated to print a sequence of characters on the document. The printing of documents "on the fly" has been used with great success in the encoding of financial documents, such as checks, in high speed encoding systems such as the one shown in United States Patent No. 4,492,161 issued to the assignee of the present application, the disclosure of which is incorporated herein by reference.

In In the prior art "on the fly" financial document encoders, magnetic ink ribbons are used to encode the documents with magnetic characters. Such magnetic ink ribbons are typically single-strike ribbons, that is, the magnetic ink associated with each character is totally removed from the ribbon during the printing of that character and the same section of ribbon cannot be used a second time. In the prior art encoders, the ribbon control mechanism provides for transport of the ribbon in one direction only, with the ribbon transport being activated to transport the ribbon in unison with a financial document in the apparatus by the sensing of the leading edge of the document lust before the document enters the print zone between the hammers and die.Specifically, an optical sensor is provided to sense the leading edge of the document and is located directly adjacent the entrance to the print zone. The ribbon transport is then deactivated in the prior art mechanism when the encoding process on a document is finished.

The prior art ribbon transport is deactivated once the last character in a series of characters, in time, is struck. It will be understood from the disclosure of the assignee's prior ijpatent that the character physically located last in a series of characters on a document is not necessarily the last character to be struck- in time. The chronological sequence of character strikes will be dependent not only on the position of the

rt character on the document but also the position of the character M on the die set. As a result, "a gap of unspent ribbon remains the die between the entrance to the print zone and theapes-i-tHen

This portion of unspent ribbon is not used in printing the next document to enter the print zone, because the ribbon transport will be activated as the next document enters the print zone.

The gaps of unspent ribbon between spent portions represents a substantial wastage of ribbon. At a typical wastage rate of 50%, the typical customer encoding one million documents per month could realize a substantial savings if the amount of ribbon wastage could be controlled, thus, a need presently exists for a ribbon control mechanism that eliminates the gaps of unspent ribbon in an "on the fly" printing apparatus.

Summary of the Invention The present invention solves the problem of wasted unspent ribbon by providing a reversible ribbon control mechanism for reversing the ribbon between documents to eliminate gaps of unspent ribbon between spent portions. The portion of the ribbon ,that is unspent after an encoding operation is salvaged by

backing up the ribbon to a point where only spent ribbon is in the print zone and the unspent portion begins at the entrance to the print zone. Because a variable amount of unspent ribbon is generated depending on the sequence of characters, in the preferred embodiment the control computer is used to calculate the exact amount that needs to be reversed.In a simplified embodiment, the ribbon is continued to be fed with the docu: until the last character of the last printed field exits print zone. Unspent ribbon then exists in the print zone

nent t 45 for entire length of the die. The ribbon is then reversed for the length of the die. Ribbon transport apparatus capable of rapidly accelerating the ribbon in both forward and reverse directions is.

provided by using vacuum columns in the ribbon supply and takeup mechanisms. A capstan moves the ribbon in the print zone between the vacuum columns.

Brief Description of the Drawings A A more complete understanding of the invention and its advantages will be apparent from the Detailed Description taken in conjunction with the accompanying Drawings in which: Figure 1 is a perspective view of the ribbon control mechanism of the present invention; ! Figure 2 is an elevation view of a die set used in conjunction with the invention; Figure Figure 3 is a partial view of a corner of a document with MICR coding; and Figures 4a and 4b are views of spent ribbons illustrating the advantages of the present invention.

Detailed Description Referring initially to Figure 1, the ribbon control mechanism of the present invention includes ribbon 10 in encoding mechanism 12 for encoding characters upon documents 14 and 16 transported along a document pathway represented by arrow 18.

Ribbon 10 is selectively transported through encoding mechanism 112 by means of a ribbon control mechanism that includes feed reel 20, feed vacuum column 22, guide rollers 24 and 26, capstan 28, takeup vacuum column 30 and takeup reel 32. Documents such as documents 14 and 16 are transported by means of a document transport system including belt534.

The document pathway includes print zone 36 between a plurality of hammers 38 and die set 40. Hammers 38 are fixed to encoding apparatus 12, as is die set 40, which is fastened to encoding mechanism 12 by way of screws 42 and base 43.

Documents 14 and 16 are illustrated as being bank checks. Typically, bank checks include pre-printed information along the lower edge thereof in zones 44 and 46 of document 14.

IfA zone 48 is provided for subsequent encoding of such information as the amount of the check. Obviously, the amount of each check is variable, and encoding apparatus 12 encodes the documents 14 and 16 with information concerning the amount of the checks in field 48. Document 16 is shown subsequent to encoding information 50. It will be appreciated that encoding apparatus '12 is specially adapted for depositing variable sequences of characters on discrete documents transported through the apparatus at high speed.

Referring now to Figure 2, die set 40 includes a series sof reverse characters 60 extending from surface 62. Surface 62 is not visible in Figure 1, but it will be understood that a document entering print zone 36 will first encounter character 64 last encounter character 66. Thus, index numerals 68 range I 1and jjfrom "1" to "24" and correspond to the position of the characters the die set. Thus, for example, the character designated by reference numeral 70 is characterized by the index number "7" because it is the 7th character from character 64.For ease of reference, the index number between "1" and "24" used to describe the the position of the character will be referred to as the "Striking Element Number" of that character.

Referring now to Figure 3, the lower right-hand corner of document 16 includes character sequence 50 as previously described in connection with Figure 1. A typical number of ''characters in sequence 50 would be twelve, and the index numbers 84 between "1" and "12" can be used to describe the position of I the characters on the document. In sequence 50, the character ideslgnated by reference numeral 80 is described by the index number "1" whereas the character designated by reference numeral i82 is described by the index number "12".For ease of reference, I ii the index number between "1" and "12" used to describe a character in sequence 50 shall be referred to as the "Character Position Number" of that character. Sequence 50 itself can be described in terms of the total number of characters in the sequence, in this example twelve, and this number may be referred ',to as the "String Length". Document 16 includes leading edge 86, (which is the first portion of the document to enter print zone 36.

Referring now to Figures 4a and 4b, ribbon portion 100 includes spent portions 102 separated by a wide portion of unspent ribbon 104. Ribbon portion 100 is illustrative of the ribbon used in the prior art apparatus where the ribbon transport system moved the ribbon only in the forward direction, stopping the ribbon between documents. By way of contrast, ribbon portion I- 106 includes spent portions 108 separated by relatively narrow unspent portions 110. The width of portions 110 is a matter of design choice and can be eliminated completely if desired.

In In operation, documents such.as documents 14 and 16 are printed while they are in horizontal motion, known as "on the ,flv" printinq. Documents are transported alonq the document I j pattiway indicated by arrow 18 through print zone 36, where hammers 38 are sequenced according to control signals to print a ;desired sequence of characters on the document.By referencing

leading edge 86 of th"e document to the die set and by knowing !; ,tlu < & A dw ULL-CLCPk II }nfewXedgeefA the desired character to be printed in each desired character position, through use of a control microprocessor, the desired characters can be printed within allowed tolerances in the desired spaces "on the fly" as the document passes through the print zone.

An unused portion of the ribbon must be present between a hammer and a die character at the instant that the hammer is 'fired to strike the die. Thus, the ribbon and the document to be printed must move in unison through the print zone. After the 'last character hammer is fired, in time but not necessarily in position, the ribbon can stop while the document proceeds through the print zone. Because the last hammer in time to fire is usually not the first hammer in position to fire, there is jlusually a portion of the ribbon left unspent which can be I salvaged by backing up the ribbon to a point where only spent ribbon is in the print zone and unspent ribbon begins at the 11entrance to the print zone.

Bidirectional capability of the ribbon control mechanism is provided by enabling capstan 28 to rotate in either the forward or reverse direction. In the preferred embodiment, a stepper motor is used in conventional fashion to advance and ;reverse the capstan in a highly controlled fashion. Stepper motors are also used in conventional fashion to drive feed reel 20 and takeup reel 32. Because the ribbon in the print zone is constantly being transported in forward directions as well as variable reverse directions, the operation of the stepper motors ;which drive feed reel 20 and takeup reel 32 is asynchronous with respect to the stepper motor which drives capstan 28.

Conventional MICR ribbon is highly stretchable, so the rapid accelerations required by the ribbon control mechanism are enabled by using vacuum columns 22 and 30. Vacuum columns are known in the art of computer tape control mechanisms, and in conventional fashion vacuum columns 22 and 30 are buffered with photocells. As will be understood by those skilled in the art, the vacuum in vacuum columns 22 and 30 is sufficient to generate sufficient forces on each side of the capstan 28 to move the ribbon in a controlled manner.

The amount of ribbon reversal can be controlled in either of two ways. Since the goal is to reverse the ribbon to the point where no unspent ribbon remains in the print zone, the worst case in terms of amount of unspent ribbon in the print zone would occur when the character on the document at Character I' Position Number "12" (Figure 3) is struck by the character in the ,die set at Striking Element Number "24" (Figure 2). In this I worst case, unspent ribbon would fill the print zone for substantially the length of die set 62.Thus, a simple way to control ribbon reversal is merely to assume the worst case each time a document is printed, stop the ribbon transport as the printed field leaves the print zone, and reverse the ribbon an amount substantially equal to the length of the character die set. A disadvantage of this approach is that the ribbon is moved I- a greater distance in most cases than is actually required, allowing more opportunity for particles to be scraped off which can result in voids in the ink layer or extraneous ink on the /documents.

The preferred way to control ribbon reversal is to calculate the precise amount of unspent ribbon remaining in the print zone when the last character in time is struck and driving ,the capstan in reverse a sufficient amount to leave only spent 'I ribbon in the print zone. Thus, the amount of reversal is a calculated amount based on the printing pattern of the just printed document. The variable reverse distance can be calculated for each sequence by the following formula: Reverse Distance = MAX(Striking Element Number + Character Position Number) - String Length, as those terms have been defined above. Thus, for each sequence, the Striking Element Number and Character Position Number for each character to be printed are summed, and the highest sum (MAX) is determined. It will be understood that the sum of the Striking Element Number and Character Position Number determines the chronological sequence in which given characters in a sequence will be struck. The maximum sum of these two numbers is then reduced by the amount of the String Length, and the Reverse Distance remains. Thus, it can be seen that the Reverse Distance is an amount corresponding to the amount of unspent ribbon between the die set and hammers when the last character in time

respect to a specific embodiment thereof, it will be understood that various changes and modifications will be suggested to one skilled in the art and it is intended to encompass such changes and modifications as fall within the scope of the appended claims.

Claims

1. An encoding apparatus for depositing variable series of characters on discrete documents transported through the apparatus, comprising: a document transport mechanism for engaging a document and transporting it through the encoding apparatus along a document pathway; a die set fixed to the apparatus and having char acters extending from a surface thereof along a por tion of one side of the document pathway; a plurality of hammers fixed to the apparatus in opposing relationship to the characters of the die set on the other side of the document pathway and disposed for striking documents in the document pathway in response to control signals;; a single-strike ink-bearing ribbon disposed on moans for guiding the ribbon from a feed reel to a take-up reel adjacent to a portion of the document pathway interposed between the hammers and characters of the die set; ribbon transport means for selectively transpor ting a portion of the ribbon along the document pathway either in the same direction and at the same speed as a document transported through the apparatus or in a reverse direction with respect to the document transport direction; and means for controlling the ribbon transport means in response to control signals to stop and reverse the ribbon transport means after the last character in a first series of characters is encoded, the ribbon being reversed to a ribbon position where encoding of a second subsequent series of characters will begin in a portion of the ribbon substantially adjacent to a portion of the ribbon cor.sumeH in prlntlns tne first series of characters.

2. The apparatus of Claim 1 wherein the ribbon is reversed a constant linear distance after each series of ,characters is printed, the distance corresponding to the amount of unspent ribbon that would result from stopping the ribbon after the last character in a series passes the last character on the die set.

3. The apparatus of Claim 1 wherein the ribbon is reversed an amount corresponding to amount of unspent ribbon between the die set and hammers when the last character in time is struck.

4. In a printing device for discrete documents continuously moving through said device, where each document passes between at least one fixed character die set on one side of the document and at least one fixed set of striking elements on the other side of the document, the document and a single strike ink-bearing ribbon moving through the character die set and striking elements in unison during printing, and the striking elements being sequenced in response to control ;signals from a control computer to print at least one desired series of characters on the document, the improvement :1 comprising: drive means for advancing and reversing the ribbon in response to control signals from the control computer; and the control computer including means for signaling the drive means to reverse the ribbon between documents to position the ribbon for printing in the portion of unspent ribbon substantially adjacent to a portion of spent ribbon.

5. The improvement of Claim 4 wherein the ribbon is reversed a fixed distance between documents corresponding to the total number of characters in the character die set.

6. The improvement of Claim 4 wherein the ribbon is reversed a variable distance after printing the series of characters on a document, the reverse distance determined by the formula: Reverse Distance = MAX(Striking Element Number + Character Position Number) - String Length, where String Length is the total number of char acters in the series of characters printed, Striking Element Number is a number between one and the total number of striking elements used print being the series of characters, and Character Position Number is a number between one and the total number of characters in the first series of characters.

7. The apparatus of Claim 3 wherein the ribbon is reversed a variable reverse distance after printing the series of characters on a document, the reverse distance determined by the formula: Reverse Distance = MAX(Striking Element Number + Character Position Number) - String Length, where String Length is the total number of characters in the first series of characters printed, Striking Element Number is a number between one and the total number of striking elements used printing the first series of characters, and Character Position Number is a number between one and the total number of characters in the first series of characters.

8. An encoding apparatus substantially as hereinbefore described with reference to the accompanying drawings.