EP0195949B1 - Printer with one or more print stations - Google Patents

Description

The invention relates to a printer mentioned in the preamble of claim 1.

Interchangeable printheads enable e.g. the use of a printer for different printing processes or types of paper.

DE-A-31 07 554 already shows a printer of the type mentioned in the preamble of claim 1. It can be adapted to different types of paper by exchanging the print head and other associated, specific devices. In addition to the print head, transport and guide means for the print carrier and the counter pressure bearing can also be replaced if necessary. All of these functional elements must be individually removed or installed. On the one hand, this means a considerable amount of work, which in general cannot be carried out by the user of the printer because of the adjustment work involved. On the other hand, with the known arrangement there is also the risk that, given the large number of functional elements to be converted, incorrect parts are assigned to one another, which must lead to malfunctions or even damage to the printer.

In contrast, there is the task of creating a printer of the generic type, which can be converted to different printing methods with little effort, so that this conversion can also be carried out by the user of the printer, an incorrect assignment of individual functional elements being largely ruled out.

This object is achieved by the features contained in the characterizing part of claim 1.

All the essential functional elements belonging to a certain printhead, which include in particular the transport and guide means for the print carrier and the platen, are combined to form a unit to be replaced as a whole. The conversion of the printer from one printing process to another is carried out by exchanging only two modules, namely the print head and the structural unit containing the other essential functional elements. It is not difficult to provide two assemblies with markings or coding profiles that make incorrect assignment improbable or impossible.

The arrangement according to the invention also enables some extremely advantageous configurations, particularly with regard to the coupling of the transport system to the central drive, which are the subject of subclaims.

Because the entire printing system, which in addition to the printhead also includes the platen, the transport and guide means for the line feed and possibly also the ink carrier device, is designed as a conversion kit, there is the possibility, for example, of a needle printhead with a substantially fixed platen and ribbon as well how to use a thermal print head with rotating platen and thermal transfer ribbon or other combinations, as will be explained.

According to one embodiment of the invention, it is provided that the interchangeable print heads of a printing system are print heads of different modes of operation, which can be controlled by a control device which is uniform for all these print heads. Different mosaic printheads may be mentioned by way of example, e.g. Ink mosaic, needle or thermal print heads, the print image of which is composed of dots in the same way and which are therefore controlled in the same way. In this embodiment, an interface between the print head and the control device that is very close to the print head can be selected; the latter need not be replaced, so that a great simplification is achieved.

The invention can be used with great advantage above all in printers with several printing stations, for example in cash register printers with one printing station each for receipt, journal and receipt. The basic equipment of the printer can be manufactured in large quantities, whereby the equipment of the various printing stations can be individually defined at any time by the customer at any time up to immediately before delivery. In addition, the user can also switch individual printing stations from one printing process to another without having to buy a completely new printer.

The printing stations, for example, are designed so that all components that belong to the printing systems are interchangeable. In order to facilitate the exchange process, at least some of the functional elements forming a printing system are combined to form a whole replaceable assembly. The design and arrangement is such that this assembly is easily accessible and can be assembled and disassembled in a simple manner. The components that are common to all usable printing systems, on the other hand, can be arranged stationary in the printer housing. In this way, especially for printers with several printing stations, there is the possibility, for example, of equipping the printing stations that are mainly used with the low-noise thermal printing system, and the less frequently used printing stations with the cheaper needle printing system, which also allows the production of carbon copies.

The printing systems can in principle be autonomous, that is to say they can be provided with all the functional elements that are important for their function. However, it is also possible to assign individual functional elements which can be used for a plurality of printing systems to the printer housing, in which case individual functional elements of the exchangeable assembly which are operatively connected to these components arranged in the printer housing can then be assigned to the printer housing the latter automatically connect to these components.

In a practical embodiment of the invention, it is provided that a printing system with a serial print head which can be placed on a carrier which is movable in the row direction in the printer housing and a writing surface which is formed on the exchangeable assembly and is stationary during operation is provided as a platen. The interchangeable assembly can also include other functional elements, such as Parts of the guide and transport means for the print carrier contain, as will be explained in more detail later. Instead of the serial printhead, however, according to the invention, a printhead which is arranged in a stationary manner in the printer housing and is designed as a thermal writing strip can also be provided, a rotatable screeching roller then being provided on the exchangeable assembly as a platen. The platen rotates when the print medium is transported, so that the platen generally does not need to be lifted off the print medium.

In a further embodiment of the invention it is provided that the interchangeable assembly between the operating position, in which the platen is in contact with the print head, and a lifting position, in which the platen is raised from the print head, is adjustably arranged on the printer housing. This on the one hand facilitates the threading of the print carrier, and on the other hand creates access to the print head, for example for the purpose of an inspection.

In a further embodiment of the invention, the conversion kits also include writing tape cartridges, so that certain cartridges can be used either for operation with dot-matrix printing heads or with thermal transfer printing heads.

Further advantages and features of the invention result from the patent claims, the drawing and the associated character description.

Several embodiments of the invention are shown in this drawing and described below.

• Fig. 1 schematisch einen Drucker mit drei Schreibstationen, wobei eine austauschbare Baugruppe mit Mitteln zum Führen und Transportieren von bandförmigen Druckträgern zweier paralleler Druckstationen vorgesehen ist;
• Fig. 2 schematisch einen Längsschnitt durch einen Drucker gemäß Fig. 1, wobei die oberen Druckstationen mit Nadeldruckköpfen ausgerüstet sind;
• Fig. 3 schematisch eine Darstellung gemäß Fig. 2, wobei die oberen Druckstationen mit einer Thermoschreibleiste als Druckkopf ausgerüstet sind;
• Fig. 4 in einer persektivischen Teildarstellung ein Drucksystem gemäß Fig. 2;
• Fig. 5 in einer perspektivischen Teildarstellung ein Drucksystem gemäß Fig. 3;
• Fig. 6 in einer perspektivischen Teildarstellung ein anderes Ausführungsbeispiel eines Drucksystems gemäß Fig. 5;
• Fig. 7 in einer perspektivischen Teildarstellung ein Ausführungsbeispiel der in Fig. 1 unten dargestellten Druckstation;
• Fig. 8 eine Darstellung gemäß Fig. 7, wobei diese Druckstation mit einer Thermoschreibleiste ausgerüstet ist;
• Fig. 9 bis 11 schematisch verschiedene Betriebsstellungen der Druckstation gemäß Fig. 8.

Show it.

• Figure 1 shows schematically a printer with three writing stations, wherein an interchangeable assembly with means for guiding and transporting ribbon-shaped print carriers of two parallel printing stations is provided.
• FIG. 2 schematically shows a longitudinal section through a printer according to FIG. 1, the upper printing stations being equipped with needle print heads;
• FIG. 3 shows a schematic representation according to FIG. 2, the upper printing stations being equipped with a thermal writing strip as a printing head;
• FIG. 4 in a partial persective representation of a printing system according to FIG. 2;
• 5 shows a perspective partial representation of a printing system according to FIG. 3;
• 6 shows a perspective partial illustration of another exemplary embodiment of a printing system according to FIG. 5;
• 7 shows a perspective partial illustration of an exemplary embodiment of the printing station shown at the bottom in FIG. 1;
• FIG. 8 shows a representation according to FIG. 7, this printing station being equipped with a thermal writing strip;
• 9 to 11 schematically different operating positions of the printing station according to FIG. 8.

The printer 2 shown in Fig. 1 comprises a printer housing 4, in which a large part of all functional elements of the printer is accommodated, and an attachment 6, which can be placed on the printer housing 4, in which further functional elements combined to form an interchangeable assembly are contained, as well is explained in more detail below. The device shown is a POS printer with three printing stations 8, 10 and 12. In the printing station 8 a receipt is issued, which can be printed on tape-like paper and torn off by means of a tear-off device 14. A continuous journal strip is printed out in the printing station 10. This is also printed on tape-shaped paper and wound onto a take-up spool 16. The printing stations 8 and 10 are arranged parallel to one another and are printed by a common print head 18 which can be moved in the direction of the arrow 20. If the print head 18 is a needle print head or a thermal transfer print head, the printing ink is transferred from an ink ribbon 22 to the print carrier 24 or 26 for receipt or journal. The ink ribbon 22 runs out of an ink ribbon cassette 28, is guided over the various printing stations and then runs back into the ink ribbon cassette 28. The printing station 12 is used to print an approximately sheet-shaped printing medium 30, which serves as a payment receipt. A print head 32 is used for printing on the print carrier 30 and is likewise movable in the direction of the arrow 20 and is preferably arranged on a common carrier with the print head 18. As can be seen in FIG. 1, the ink ribbon 22 is guided such that it can also serve as an ink carrier for the printing station 12. If the upper printing stations or the lower printing station work according to a method in which an ink ribbon is not required, the ink ribbon or the printing head is displaced in this station perpendicular to the line direction so that the printing head lies next to the path of the ink ribbon.

The attachment 6 contains guide and transport means for the print carriers 24 and 26 as well as the platen against which the print carriers abut during the printing process. These functional elements are different, depending on whether it is in the printing systems used in stations 8 and 10 z. B. is dot matrix or thermal printing systems, as will be explained in more detail below. The entire essay with the one in it contained functional elements combined into an assembly is interchangeable, so that the printer 2 can be converted from one printing process to another in a few simple steps. In addition, the attachment 6 is arranged so as to be pivotable about the axis 34, so that the threading of the print carriers 24, 26 running from the supply rolls arranged in the printer housing 4 is facilitated and access to the functional elements arranged in the printer housing 4, in particular the print heads 18, 32 and the ribbon cassette 28 is made possible. In addition, when the attachment 6 is pivoted into the operating position shown, functional elements arranged in this attachment are coupled to functional elements arranged in the printer housing 4, as will be explained further below.

The transport means 36 and the pressure counter bearing 38 are arranged on a common frame 40 which is mounted in the printer housing 4 so as to be adjustable in the direction of the arrow 42. In the example shown in FIG. 1, the pressure counter bearing 38 is designed as a simple pressure bar with a flat writing surface, as is used, for example, in cooperation with needle print heads. The frame 40 with the transport means 36 and the pressure counter bearing 38 are in turn designed as an exchangeable assembly. When changing the printing process of the printing station 12, the frame 40 and the print head 32 are exchanged.

FIG. 2 shows a very simplified, schematic illustration of a section through the printer 2 according to FIG. 1. All printing stations 8, 10 and 12 are designed as needle printing stations. The upper printhead 18 interacts with a platen 44 arranged on the underside of the attachment 6, which is designed as a flat writing surface. The attachment 6 also contains guide channels 46, 48 (see also FIG. 1) for the print carriers 24, 26 and counter-rollers 50, which interact with driven transport rollers 52 arranged in the printer housing and further convey the printing paper running off the supply rollers 54. As shown in FIG. 2, the attachment 6 can be pivoted into a lift-off position shown in dashed lines, in which the platen 44 formed on the underside of the attachment 6 is lifted off the print head 18 and the counter-rollers 50 are lifted off the transport rollers 52. This position enables the band-shaped print carriers 24, 26 to be threaded into the guide channels 46 and 48, as well as access to the functional elements arranged in the printer housing.

The lower print head 32, also designed as a needle print head, for printing on the print carrier 30 interacts with the pressure counter bearing 38 arranged on the frame 40 and designed as a pressure bar. In addition, driven transport rollers 36 are arranged on the frame 40, which cooperate with counter rollers 56 arranged in the printer housing. The frame 40 is adjustable in the direction of the arrow 42. In a lower lift-off position, the platen 38 is lifted from the printhead 32 and the transport rollers 36 are lifted from the counter-rollers 56, so that the pressure carrier 30 can be inserted until it abuts the stop 58. The adjustment option in the direction of arrow 42 also serves to lift the platen from the print head 32 for line transport, as will be described in more detail further below.

Fig. 3 shows an arrangement according to Fig. 2, but in which the printing stations 8, 10 are converted for a thermal printing process. The printing station 12, however, is still equipped with a dot matrix printing system, so that it does not have to be described again here.

Instead of a wire print head, a thermal print head 60 designed as a thermal writing strip is provided in FIG. 3, which is pivotally mounted in the printer housing about an axis 62. A compression spring 64 keeps the print head 60 in constant contact with the associated platen.

The attachment 66 corresponds in its shape and dimensions essentially to the attachment 6 in FIG. 2. It also contains guide channels 68, 69 for the print carriers 24, 26 as well as mating rollers, not shown in this figure, which have driven transport rollers arranged in the printer housing work together. This arrangement corresponds to the arrangement shown in FIG. 2 and therefore need not be described again here.

A platen roller 70 serves as the pressure counter bearing for the print head 60 and is drive-connected via a drive belt 72 to a pulley 76 arranged on the axis 74 of the counter rollers. In addition, intermeshing gears 80, 82 are arranged on the axis 74 of the counter rollers and on the axis 78 of the transport rollers, which transmit the drive movement of the transport rollers in a suitable ratio to the platen roller 70. The attachment 66 is in turn arranged in FIG. 2 so as to be pivotable about the pivot axis 34, so that the gears 80 and 82 come into engagement with one another when the attachment 66 is pivoted into the operating position shown.

The thermal print head 60 is constantly against the platen 70 or the print carrier 24, 26 bearing against it, provided that it is a pure thermal print without the use of an ink ribbon or the like. The arrangement is such that the thermal print head 60 lies above the ink ribbon 22, which is still used for the lower printing station 12.

FIG. 4 again shows a perspective illustration of details of an arrangement according to FIG. 2. The two print carriers 24 for the receipt and 26 for the journal each run from assigned supply rolls 54 and are guided over the transport rolls 52 against which the counter rolls 50 bear . The print head 18 can move in the direction of the arrow 20 over a line width covering both print carriers 24, 26 will. Gear wheels 82 are arranged on the axis 78 of the transport rollers 52, which serve when converting the printing stations to drive a rotatable platen roller, as was described with reference to FIG. 3.

FIG. 5 shows a perspective illustration of details of an arrangement according to FIG. 3. The pressure carriers 24, 26 run from the supply rollers 54 between the transport rollers 52 and the associated counter rollers 50 to the pressure counter-supports 70 designed as platen rollers, and from there through the not shown guide channels of the attachment 66 to the outside. The platen rollers 70 are driven by pulleys 71, drive belts 72 connected to them, pulleys 76 arranged on the axis 74 of the counter rollers 50 and the gearwheels 80 arranged on the same axis, each of which engages with gearwheels 82 on the axis 78 of the transport rollers 52 are. In the exemplary embodiment shown in FIG. 5, the axis 74 is formed from two coaxial, interlocking axes, each of which is connected to one of the gear wheels 80; one of these axes is used to drive the platen for the receipt, the other to drive the platen for the journal.

The thermal writing strip 60 is likewise divided into two, one part being intended for printing on the print carrier 24 and the other part for printing on the print carrier 26, as can be seen in FIG. 5.

FIG. 6 shows a modification of the arrangement according to FIG. 5. The printing station 84 takes up the entire width of the printer: the print carrier 86 consists of two layers 88, 90. It in turn runs from a supply roll 92 via a transport roll 94 and as Platen roller formed pressure counter bearing 96 to the outside. A single print head 98, which extends over the entire width of the print carrier 86 and is designed as a thermal writing strip, describes, for example, directly the layer 88 consisting of active paper and indirectly in a thermal transfer process by means of dyes arranged on the back of the layer 88, the layer 88 being a tear-off receipt , location 90 serves as a continuously wound journal. The platen roller 96 is in turn driven by a belt drive 100 and a gear connection 102 from the driven transport roller 94, as need not be described in detail.

FIG. 7 shows a perspective view of a printing station 12 according to FIGS. 1 to 3. Corresponding components are provided with corresponding reference symbols. The platen 38 and the transport rollers 36 are arranged on a common frame 40, which is arranged in the direction of the arrows 42 in the printer housing. The frame 40 can assume two or three different positions depending on the type of printing system used. 2 or 3 as well as in an ink mosaic printing system, there are two positions.

In an inoperative position, both the platen 38 from the printhead 32 and the transport rollers 36 are lifted from the counter rollers 56, so that a print carrier can be inserted up to the stops 58. In an operating position of the frame 40, the transport rollers 36 bear against the counter rollers 56 or the print carrier arranged between them, while the print counter bearing 38 is at a sufficient distance from the print head 32 for the line transport of the print carrier, at which the print carrier can be printed. The print head 32 can be a needle print head, in which case an ink ribbon must then be arranged between this print head 32 and the print carrier, as shown in FIGS. 1 to 3. The printhead can also be designed as an ink mosaic printhead, an ink ribbon being omitted.

If the printing station 12 is to be converted to a thermal printing process, the frame 40 with all the functional elements arranged thereon and combined into an exchangeable assembly is exchanged for a frame 104 which has the functional elements required for the thermal printing process, as shown in FIG. 8 . The platen 106 is designed as a rotatable platen roller which is coupled to the axis of the transport rollers 110 via a gear transmission 108. A thermal writing strip, in turn, serves as the print head 112, against which the platen 106 can be placed from below. In this case, the frame 104 can assume three positions, namely an inoperative position, a transport position and an operating position.

9 to 11 schematically show the possible positions of the frame 104. In FIG. 9, this frame 104 is in its lower inoperative position, in which the transport rollers 110 are lifted off the counter rollers 56 and the platen roller 106 is lifted off the platen 112. In Fig. 11, the frame 104 is moved upwards so far that the transport rollers 110 bear against the counter-rollers 56, so that it is possible to transport a printing medium located between these two roller systems. As can be seen in FIG. 11, the platen roller 106 does not yet bear against the platen 112 in this position. 10, the frame 104 is in its upper operating position, in which the platen roller 106 bears against the platen 112, so that a print carrier located between them can be printed. As is apparent from FIG. 10, the counter rollers 56 are resiliently mounted in the infeed direction of the frame 104, so that they can join in the movement of the transport rollers 110 from the position shown in FIG. 11 to the position shown in FIG. 10. On the other hand, there is also the possibility of rotating the frame 104 from the position it holds in FIG. 11 clockwise about the axis 114 of the transport rollers 110 until the platen roller 106 bears against the platen 112. The possibility of the platen roller during the Lifting the transport of the print carrier off the writing bar is necessary above all when using a thermal transfer method in which a sensitive color pigment carrier is arranged between the platen roller 106 and the print carrier.

Claims (19)

1. A printer having at least one printing system which comprises an exchangeable printing head (18; 32), an exchangeable printing abutment (38; 44; 70; 106), exchangeable conveying and guide means (36, 56; 50, 46, 48; 76, 68, 110, 56) for a print support (24, 26, 30) moving through the printing system, and possibly other exchangeable function elements which co-operate with the printing head, characterised in that at least the printing abutment (38; 44; 70; 106) and the conveying and guide means (36, 56; 50, 46, 48; 76, 68, 71; 110, 56) of each printing system are combined to form an exchangeable unit.

2. A printer according to claim 1, characterised in that the exchangeable printing heads (18, 60) of a printing system each are printing heads operating in different ways and controllable by a control facility unitary for such heads (18, 60).

3. A printer according to claim 1 or 2, characterised In that the printing system comprises: a serial printing head (18, 32) mounted in the printer casing (4) for linewise movement; and a printing abutment (44, 38) embodied as a writing beam with a flat writing surface.

4. A printer according to any of claims 1-3, characterised in that the printing system comprises: a printing head (60, 112) fixedly disposed in the printer casing (4) and embodied as a thermowriting strip; and a rotatable writing. roller as printing abutment (70, 106).

5. A printer according to any of claims 1-4, characterised in that the exchangeable group comprising the printing abutment (44, 70, 106) and the conveying and guide means (50, 52, 46, 48; 80,82,68,70) is disposed on the printer casing (4) for movement between an operative position, in which the printing abutment (44, 70, 106) engages the printing head (18, 60, 112), and a disengaged position, in which the printing abutment (44, 70, 106) is out of engagement with the printing head (18, 60, 112).

6. A printer according to any of claims 1-5, characterised in that the printing head (18, 60) is disposed near the top of the printer casing (4) with upwardly directed writing elements and that the exchangeable unit is in the form of a top attachment (6, 66) which can be placed on the printer casing (4) and which comprises: guiding and conveying means devised mainly on its underside; and a printing abutment (44, 70) for the print support (24, 26).

7. A printer according to claim 6, characterised in that the top attachment (6, 66) can be mounted on the printer casing (4) for pivoting around a spindle (34) parallel to the line direction, and when the top attachment (6, 66) is pivoted into an operative position on the printer casing (4), counter rollers (50) disposed thereon engage conveying rollers (52) in the printer casing (4).

8. A printer according to claim 7, characterised in that the printing abutment (70, 96) is in the form of a rotatable writing roller adapted to be coupled with the conveying rollers (52, 94), and when the top attachment (66) is pivoted into its operative position drive-transmitting means (82, 102) connected to the conveying rollers (52, 94) are drivingly engaged with drive-transmitting means (71, 100) on the writing roller.

9. A printer according to any of claims 1-5, characterised in that the printing head (32, 112) is disposed near the bottom of the printer casing with downwardly directed writing elements and the exchangeable unit comprises a frame (40, 104) or the like mounted for vertical movement below the printing head (32, 112) in the printer casing and carrying: conveying rollers (36, 110) co-operating with counter-rollers (56) arranged in the printer casing; and the printing abutment (38, 106).

10. A printer according to claim 9, characterised in that the frame (40) is adjustable between an inoperative position, In which the conveying rollers (36) or the printing abutment (38) are out of engagement with the driving rollers (56) and the printing head (32), into an operative position, in which the conveying rollers (36) are in engagement and the printing abutment (38) is at a predetermined writing distance from the printing head (32).

11. A printer according to claim 9, characterised in that the frame (104) is adjustable between an inoperative position, in which the conveying rollers (110) and the printing abutment (106) are out of engagement with the driving rollers (56) or printing head (112), through a conveying position, in which the printing abutment (106) is in the disengaged state but the conveying rollers (110) are in the engaged state, into an operative position, in which the printing abutment (106) engages the printing head (112) and the conveying rollers (110) are in engagement with the counter-rollers (56).

12. A printer according to claim 11, characterised in that the frame (104), in addition to its vertical movement, is pivotable around the spindle (114) of the conveying rollers (110).

13. A printer according to one of claims 11 or 12, characterised in that the counter-rollers (56) are resiliently mounted in the pressing- on direction.

14. A printer according to any of claims 9 and 11-13 characterised in that the printing abutment (106) is a rotatable writing roller coupled with the conveying rollers (110).

15. A printer according to one of claims 9 and 10, characterised in that the printing abutment (38) is in the form of a writing beam fixedly disposed in the frame (40).

16. A printer according to any of claims 1-15, characterised in that as further function elements ribbon cassettes (28) are associated with the printing systems and cassettes adapted for operation with pin printing heads or with thermotransfer printing heads can be used at choice.

17. A printer according to any of claims 1-16, characterised in that individual function elements (50, 80) of the exchangeable group, the latter elements co-operating functionally in operation with components (52, 82) arranged in the printer casing (4), engage automatically with the components (52, 82) when the group is used.

18. A printer according to any of claims 1-17, characterised in that a number of printing stations (8, 10, 12) having separate printing systems for printing strip-like and/or individual substantially sheet-like print supports (24, 26, 30) are provided in the printer casing (4).

19. A printer according to any of claims 1-18, characterised In that an ink support facility (22) is provided as further exchangeable function elements.

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