EP0127145A1

EP0127145A1 - Dual head, three station printer

Info

Publication number: EP0127145A1
Application number: EP84105950A
Authority: EP
Inventors: Karl Tommy Wincent
Original assignee: Litton Systems Inc
Current assignee: Northrop Grumman Guidance and Electronics Co Inc
Priority date: 1983-05-26
Filing date: 1984-05-24
Publication date: 1984-12-05
Also published as: JPS602389A

Abstract

A dual head, three station high speed printer for recording retail transactions comprises a single worm driven carriage (40) which supports two side-by-side print heads (36, 38). A tear bar is positioned to impart a 90° change in the orientation of the receipt tape (16) after printing, and the journal tape take-up roll (24) imparts a 180° change in the orientation of the journal tape (14) after printing, whereby both tapes are immediately readable after advancement beyond the printing station. Carriage position detectors (46, 47) are used to increase cycle speeds by eliminating carriage travel across the journal tape (14) when it is not being printed, and pinch rollers (48, 49, 52, 54) which drive the tapes are separable in order to facilitate replacement of the tapes.

Description

High speed printers, particularly those associated with recording retail sales, are normally required to record transactions in more than one form. In some instances, three records are made for each sale, a printed customer receipt, a journal record for the store, and a separate record slip for charge transactions.
The time taken to print this data in these forms, though on an absolute basis can be quite fast, on a relative basis can materially effect queue times in these days of mass merchandising. Printers capable of printing these multiple data forms simultaneously rather than sequentially can reduce printing time by as much as one-third. Additionally, the cost to the retailer of a single unit having three printing stations is substnatially less than the combined cost of a plurality of units, each having only one ore two printing stations.
Character generation in high speed printers is normally accomplished by a technique known as dot-matrix printing. The dot-matrix system employs heads which sequentially or in parallel cause the ends of print wires, acting through an inked ribbon, to create a dot pattern making up alpha-numeric characters on paper or other record carriers as the head traverses the paper. Typically, a dot-matrix character is created from a 5x9 matrix of dots and, typically, dot-matrix heads can create 155 characters per second. Use of a plurality of dot-matrix print heads in parallel offers the obvious advantage of multiplying the rate of character gereration by the number of heads so used.
Use of parallel heads in a single printer suggests the need for bulk in its packaging and also suggests the need for a myriad detailed parts thereby increasing cost and decreasing reliability. U.S. patent 3,910,396 issued to Eischen et al, while showing a dual head three station printer, exhibits these undesirable characteristics. In contrast thereto, a parallel head printer made up of no more components than a single head, and being of compact design, would be highly desirable.
Other printer characteristics contribute to overall queue time including the replenishing of paper tapes for receipt and journal records. A printer which is so constructed as to simplify the tape replacement process is both faster and less likely to create frustration in the counter clerks.
Some multiple head printers, due to their geometry, print on the back side of the paper as seen by the operator. In order for the operator to determine if the printer is functioning or for the operator to audit the data entries, particularly for customer receipts, the operator must interrupt their more productive activity to examine the underside of the paper.

SUMMARY AND OBJECTS OF THE INVENTION

According to the invention a two head, three print station, high speed printer is provided which offers the advantages of a simple, parallel head printer and none of the above recited disadvantages of present art printers and at the same time is so constructed as to be contained in a compact package.
It is therefore an object of the invention to provide a high speed multiple head printer for recording transaction data on three separate record carriers such as customer receipts, store journals, and charge slips.
It is also an object of the invention to provide a high speed dot-matrix printer in which the record carriers are so positioned in the printer that the information printed thereon is visable and readable by the operator immediately after being printed.
It is further an object of the invention to provide a printer which is readily serviced by the operator for routine activities such as paper replenishment and which allows for operator audit of the printer without interruptions.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an isometric view of the printer.
Figure 2 is an exploded view of a portion of the printer shown in Figure 1.
Figure 3 is a side view of the paper tape feed and drive mechanism shown in Figure 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A high speed, three station, dual head printer can be divided for ease of description into three reasonably distinct parts, the paper feed and drive mechanism, the dual head support and drive mechanism, and the power transmission portion of the printer.
Figure 1 is an isometric view of the major elements of a three station printer 10. The entire unit mounts on a frame assembly 12 and includes a journal record paper tape 14, a customer receipt tape 16 and a horizontal slip slot 18 for insertion of a separate slip such as a charge sale record slip. A journal paper supply roll 20 furnishes the journal record tape 14 through a pair of pinch rolls (not seen in this view) back over a print platen 22 to a driven take-up reel 24 for machine storage. The receipt tape 16 passes through a separate pair of pinch rolls (also not seen in this view) past the underside of the print platen 22 and behind a tear bar 26 which functions to provide a serrated cutting edge and a guide to position the printer paper to be readily visible to the operator. A record slip may be inserted into the horizontal slip slot 18 between an inked ribbon 28 and a second printing platen 30 and on into a third pair of pinch rolls (not seen in this view). The inked ribbon 28 travels in an elongated loop originating in a cartridge 32 extending over the second print platen 30 through an adjunctive housing 34, under the print platen 22, and back into the cartridge 32.
The print heads 36 and 38 are mounted to a single carriage 40 which engages a helical slot 41 in a worm shaft 42 through an engagement nut (not shown). The carriage 40 also slideably engages the guide rod 44 at a yoke 45 to prevent rotation of the carriage as the worm shaft 42 rotates. The side-by-side mounting of the print heads 36 and 38, rather than a back-to-back mounting, allows the combination to have a low height which contributes to the overall compactness of the printer mechanism.
Referring to Figures 2 and 3, the supply roll 20 holds a paper tape 14 for the journal record. The tape 14 is fed through a pair of pinch rolls 48 and 49 which drive the tape past the underside of the print platen 22 which has a formed print surface 50 to provide a backing for the print head 38. The journal tape 14 is routed back over the top of the platen 22 to the driven take-up reel 24. The receipt tape 16 is also fed through a pair of pinch rolls 52 and 54 which drive the tape past the underside of the print platen 22 and the print surface 50. The receipt tape 16 is vertically positioned by the tear bar 26 which is serrated to faciliate receipt cut-off. Because both the journal tape 14 and the receipt tape 16 are printed on their underside by the print head 38 which is facing upwardly, reversal of both tapes 14 and 16 by the take-up reel 24 and the tear bar 26, respectively, around the print platten 22 to the top surface thereof will result in the tapes 14 and 16 being directly readable without further manipulation by the machine operator.
The platen 22 has attached to it end members 56 through which the platen is pivotally mounted to the frame assembly 12 at the pivot pins 58 (one shown). The pins 58 engage the frame 12 at slotted holes 60 (one shown) and allow the platen 22 and end members 56 to rotate about the pivots 58 motivated by the biasing force of wound springs 62 (one shown) which engage the end members 56 at a position 63 and the frame at a position 64. Two clips 66 attached to the end members 56 engage the guide rod 44 to secure the platen 22 in a lowered position. When rotated about their pivots 68, the clips 66 disengage the rod 44 and the springs 62 cause the platen 22 to rotate about the pivot 58 thereby creating a substantial gap 70 between the pinch rolls 52 and 54 and 48 and 49 allowing for easy threading of replacement paper tapes. After the tapes have been loaded, the platen 22 may be lowered, reengaging the clips 66 to the guide rod 44. In this process, the pinch rolls 48 and.49 and 52 and 54 contact as the platen 22 is lowered. At that point, the pivot for rotation shifts from the pins 58 to the rolls and the pivot pins 58 move through the slots 60 against the bias of the spring 62, thus creating the roll pinch force.
A second printing platen 30 provides a backing for the print head 36 which imprints charge slips inserted into horizontal slip slot 18, seen in Figure 1. The horizontal orientation of slip slot 18 allows a receipt placed therin to remain in place, without further attention by the machine operator, thus freeing the operator's hands for other tasks. Once printing on the charge slip has been initiated, another pair of pinch rolls 74 and 76 engage the inserted slip and drive it as it is being imprinted, and discharge the slip after imprinting.
The dual head support and drive mechanism is comprised of the carriage 40 which supports the dual heads 36 and 38. The carriage 40 engages the helical slot 41 of the worm shaft 42 by means of a nut (not shown) such that, as the shaft 42 rotates, the carriage 40, together with the heads 36 and 38, move along the shaft and across the platens 22 and 30. The carriage 40 also engages the guide rod 44 by means of a yoke 45 to stablize the carriage and prevent its rotation when driven by the worm shaft 42. As the print heads 36 and 38 traverse the platens 22 and 30, they are electrically excited so as to imprint alpha-numeric characters on some or all of the record carriers: the journal tape, the receipt tape and the charge slip, by means of the print wire ends of the heads contacting the record carriers through the inked ribbon 28.
The position of the carriage 40 may be sensed by two end detectors 46 and a center detector 47 to control the movement of the carriage 40 along the worm shaft 42. For example, when printing non-sales information such as salutations and company slogans on the receipt tape 16., it is not necessary to print the same information on the journal tape 14. Accordingly, the print head may be controlled by the right hand end detector 46 and the center detector 47 to cycle back and forth across receipt tape 16 only, without traversing journal tape 14, so that such information may be printed onto receipt tape 16 in a minimum amount of time.
The power transmission section of the high speed printer, as shown in Figure 2, includes a DC motor 78 which drives a gear train comprised of gears 80, 82, 84, and 86. Gear 80 is directly driven by the motor 78 and gear 86 directly drives the worm shaft 42. The gears 82 and 84 are rotatively supported by the frame assembly 12. The gear 82 is attached to spur gear 88 which in turn engages and drives a gear 90 to which is attached a number of cam surfaces (not shown) which, through conventional linkages, advance on command the journal tape pinch rolls 46 and 48, the receipt tape pinch rolls 52 and 54, and the inked ribbon 28.
A stepper motor 92 drives the charge slip pinch rolls 74 and 76 through a gear 94 attached to the shaft of the motor 92 and a gear 96 attached to the roll 76. Both the motors 78 and 92 are individually encoded and through electronic controls (not shown), the precise axial location of the heads 36 and 38, as well as angular position of the pinch rolls 74 and 76, is determined for print control of the heads and line location of the charge slip.

MODE OF OPERATION OF THE PREFERRED EMBODIMENT

When an operator enters a transaction, the DC motor 78 is powered and rotates the worm shaft 42 through the gear train made up of gears 80, 82, 84, and 86 thereby causing the heads 36 and 38 to traverse the platens 22 and 30. At precise positions in the traverse, determined by the encoded position data, the heads 36 and 38 are electrically powered to create alpha-numeric patterns from a matrix of dots made by the ends of the wire print rods contacting the record carriers through the inked ribbon 28. When the heads reach the opposite end of the worm shaft 42, the engaging nut of the carriage 40 enters a circumferential segment 43 of.the helical slot 41 allowing the worm shaft 42 to turn freely without effecting the position of the carriage 40. At this and the opposing end of travel, both, this continued rotation allows for the cam surfaces attached to the gear 90 to advance the journal and receipt tapes through pinch rolls 48 and 49 and 52 and 54, respectively, as the motor 78 continues to rotate driving the gear 90 through the gear train made up of gears 80, 82, 88, and '90. While the journal and receipt tapes are being advanced, the charge slip, if one is being imprinted, will also be advanced. After the tapes and slip are advanced, the direction of rotation of the motor 78 is reversed, reversing the worm shaft 42 driving the heads 36 and 38 back across the platens 22 and 30 and imprinting in the opposite direction. After recording the complete transaction, the journal tape 14 is wound for storage, the receipt tape 16 is advanced in order to position it above the tear bar 26, and the charge slip, if any is discharged by the pinch rolls 74 and 76.

Claims

1. A dual print head, three station, high speed printer for recording retail transactions on record carriers such as a journal tape (14), a receipt tape (16), and charge slips by means of dot matrix generation of alpha numeric characters comprising in combination an inked print ribbon (28) supported on the printer in the shape of an elongated loop, a single carriage (40) supporting the two print heads in a side by side relationship within the elongated loop, characterized in that the first print head (38) prints through the top portion of the loop and the second print head (36) prints through the bottom portion of the loop, a first print platen (22) adjacent the top portion of the loop and a second print platen (30) adjacent the bottom portion of the loop, wherein the receipt tape (16) is between the first print platen and the inked print ribbon, and a tear bar (26) is positioned to impart a 90° change to the orientation of the receipt tape (16) after printing, whereby the receipt tape (16) is immediately readable upon advancement of the receipt tape (16) after printing.

2. The dual head printer of claim 1 further characterized in that a take up reel (24) reverses the orientation of the journal tape (14) after printing, whereby the journal tape (14) is immediately readable upon advancement of the journal tape after printing.

3. The dual head printer of claim 1 further characterized in that a horizontal slip slot (18) receives a separate record carrier, whereby the second print head (36) backed by the second print platen (30) is positioned to print on the second record carrier.

4. The dual head printer of claim 2 further characterized in that two spaced end detectors (46) and a center detector (47) located between the end detectors (46) for detecting the position of the carriage, whereby the carriage (40) and the dual print heads may be cycled between the center detector and one of the end detectors to shorten the path traveled by the carriage and to reduce the time required to produce a line of print.