EP0697939B1 - Cutting device for cutting a printing carrier in a printer - Google Patents

Abstract

A cutting device for cutting a printing carrier in a printer (10), especially in a till printer, has a blade (22) movable along at least one guide (28) against a fixed counter-blade (24) which, when open, provides an aperture (20) through which the printing carrier can pass and, when closed, at least partly cuts through the printing carrier. The blade (22) can be moved by an adjuster between the open and closed positions. The blade (22) has at least two guide components (38) fitted at a distance apart on the side away from the cutting edge (42) of the blade (22). The adjuster (30) penetrates into the guide components (38) to move the blade (22).

Description

The invention relates to a cutting device for cutting a print carrier in a printer, in particular in a cash register printer, with a knife which can be moved along at least one guide track against a stationary counter knife, which in an open position releases an opening for carrying out the print carrier and which, in the closed position, at least releases the print carrier has partially cut through, the knife being movable between the open position and the closed position by an adjusting device.

Such a cutting device is known from DE 34 45 744 A1. It is used to selectively cut or cut a paper strip in a POS printer. The knife is connected to a sliding block, which is guided in an eccentric sliding track of a sliding block. When the link disk rotates, the knife executes a lifting movement, the paper web being cut completely or only partially, depending on the direction of rotation of the link disk. Cutting forces occur during the cutting movement, which can cause the knife to jam. This causes wear on the guideways and the quality of the cut can be impaired.

It is an object of the invention to provide a cutting device which works with high cutting quality and low wear.

This object is achieved for a cutting device of the type mentioned above in that the knife has at least two guide elements which are arranged at a mutual distance on the side of the knife facing away from the cutting edge of the knife, and in that the adjusting device for adjusting the knife into the guide elements intervenes.

It is achieved by the invention that the adjusting device guides the knife along at least two places along the guideway. As a result, the knife cannot tilt even when lateral cutting forces occur. The guideway on which the knife slides is therefore less subject to wear. Furthermore, due to the precise guidance of the knife, the cut is carried out evenly, so that a high cut quality is created. In addition, the force required for cutting is in several places of the knife, so that lower partial forces also result on the corresponding guide elements. As a result, bearing wear is reduced and the cutting device operates more reliably overall.

In a preferred embodiment of the invention, plastic bearings are used as guide elements, into which pins of the adjusting device engage. These plastic bearings can be snapped into corresponding openings in the knife by means of a clip connection, so that simple assembly results. By using plastic bearings, the pins slide in the guide element with little friction, so that the force remains small and the wear is further reduced.

In another exemplary embodiment, the guideways are arranged in a plane which runs parallel to the surface of the counter knife on which the knife slides during cutting, the plane being arranged at a small distance below the surface. These measures compensate for manufacturing tolerances, so that overall an inexpensive construction of the cutting device results.

A further development of the aforementioned embodiment provides that the outer corners of the cutting sections run obliquely upwards so that the knife is guided onto the surface of the counter knife during the cutting movement. These measures ensure the operational safety of the cutting device even with a relatively large mutual distance between the surface of the counter knife and the plane of the guideways.

Another development is characterized in that the knife is guided against the guideways under spring pressure. The spring pressure can be selected so that the knife is slightly bent downward in an area between the guideways. This ensures that the cutting edge of the knife lies closely against the cutting edge of the counter knife along its entire length and thus brings about a clean cut. These measures also result in a self-sharpening effect on the cutting edges of the knife and the counter knife.

Figur 1

einen Kassendrucker mit einer Schneideinrichtung, die durch eine Stellvorrichtung angetrieben wird,

Figur 2

eine schematische Darstellung der Schneideinrichtung, die durch die Stellvorrichtung betätigt wird,

Figur 3

eine schematische Ansicht der Stellvorrichtung von der Seite und von oben,

Figur 4

eine schematische Ansicht der Stellvorrichtung in einem Zustand, bei dem die Schneideinrichtung aktiviert wird,

Figur 5

eine schematische Ansicht der Stellvorrichtung in einem Zustand, bei dem das Messer einen Vollschnitt ausführt,

Figur 6

eine schematische Ansicht der Stellvorrichtung in einem Zustand, bei dem ein Teilschnitt ausgeführt wird,

Figur 7

einen Schnitt durch das Messer und den Schwenkbügel,

Figur 8

eine Prinzipdarstellung des Messers im federnd vorgespannten Zustand, und

Figur 9

einen Schnitt durch das Gegenmesser und das Messer mit hochgebogenen Schneidenenden.

An embodiment of the invention is explained below with reference to the drawing. In it shows

Figure 1

a POS printer with a cutting device which is driven by an actuating device,

Figure 2

1 shows a schematic illustration of the cutting device which is actuated by the adjusting device,

Figure 3

a schematic view of the actuator from the side and from above,

Figure 4

1 shows a schematic view of the adjusting device in a state in which the cutting device is activated,

Figure 5

2 shows a schematic view of the actuating device in a state in which the knife makes a full cut,

Figure 6

1 shows a schematic view of the adjusting device in a state in which a partial section is carried out,

Figure 7

a cut through the knife and the swivel bracket,

Figure 8

a schematic diagram of the knife in the spring-loaded state, and

Figure 9

a section through the counter knife and the knife with curved cutting ends.

In Figure 1, a cash register printer 10 is shown, in the side walls 12 guide rails 14 are mounted. These guide rails 14 guide a print head holder 16 along a path that runs parallel to a line to be printed. A paper supply roll 18 is mounted between the side walls 12, the paper web of which is guided past the print head (not shown) via a print abutment (not shown) for printing. The paper web is guided through an opening 20 between a knife 22 and a counter knife 24 of a cutting device 26. This cutting device 26 is shown in FIG. 1 in its open position.

The knife 22 is laterally mounted on guideways 28, only one of which is visible. An adjusting device 30 with a control disk 32 actuates the knife 22 for cutting the paper web. A switching device 34 can be used to set whether the paper web is cut completely or only partially. For this purpose, an operating button 36 is to be adjusted.

FIG. 2 shows a schematic view of the cutting device 26 together with the adjusting device 30. The knife 22 has two plastic guide elements 38 arranged at a mutual distance, the connecting line of which runs approximately parallel to the cutting edge 40 of the counter knife 24. The knife 22 is a stamped part, which is made of thin spring plate. The counter knife 24 is made from a stable strip of spring band, which is inserted into the slot of a holder made of plastic. The knife 22 has a cutting edge 42 which consists of two cutting edge sections which run obliquely outwards from the cutting edge center in the direction of the cutting movement. In the middle of the cutting edge 42 there is a recess 44 in a V-shape, the tip of which faces away from the counter knife 24. This shape of the cutting edge centers the knife 22 during the cutting movement, so that a high-quality cut is achieved. The knife 22 can have a shape adapted to the width of the paper web to be cut. In the present example, the knife 22 has a cutout 46 in order to reduce the width of the cutting edge 42. In an embodiment 48 shown in dashed lines, the knife has an enlarged width and three guide elements 38.

The guide elements 38 of the knife 22 are mounted on pins 50 of a swivel bracket 52, which is rigidly connected to a swivel shaft 54, which in turn is rotatably mounted in the printer housing. The pivot shaft 54 can be pivoted when a control disk 32 rotates. The pivot shaft 54 is rigidly connected at the end facing the control disk 32 to a U-shaped retaining bracket 56 which holds an engagement lever 60 which can be pivoted about an axis of rotation 58. The engagement lever 60 is with a spring (not shown) in the direction of Control disc 32 biased. It carries a control pin 62 at its outer end, which is pressed elastically against the control disk 32 by the aforementioned spring.

The control disk 32 has a control groove 64 running in the circumferential direction, the radial distance from the center of the control disk 32 increasing over the angle of rotation in the direction of the arrow LL. The engagement of the control pin 62 in the control groove 64 can be prevented by a locking device 66 which covers the control groove 64 with a bolt 70 guided in an elongated hole 68. A compression spring 72 biases the bolt 70 in the direction of the pivot shaft 54.

When the control disk 32 rotates in the direction of the arrow LL, a control cam 74 firmly connected to it moves the bolt 70 to the right in FIG. 2 via a nose 76 and releases the control pin 62 so that it can engage in the control groove 64. During this rotation, the control disk 32 is rotated to an angle of rotation which is not reached during the printing of a line. During a subsequent rotation of the control disk 32 in the direction of the arrow RL, the control pin 62 is guided in the control groove 32, the engagement lever 60 executing a stroke along a control path 78. This stroke is transmitted from the bracket 56 via the pivot shaft 54 and the pivot bracket 52 to the knife 22, which moves from the open position into a closed position against the counter knife 24, thereby cutting through the paper strip.

The control groove 64 ends in a curve outlet 80, which guides the control pin 62 out of the guidance of the control groove 64. The knife 22 is near the recess 44 via a tension spring 82 connected to the swivel bracket 52 so that the cutting edge 42 of the knife 22 is biased in the direction of the swivel bracket. This bias also causes the knife to retract to its open position. As a result of the force of the tension spring 82, the swivel bracket 52 swings back together with the engagement lever 60 into its starting position, which corresponds to the open position shown in FIG. 2.

The stroke of the knife 22 is dimensioned such that when the control pin 62 is led out of the control groove 64 through the curve outlet 80, the recess 44 covers the cutting edge 40 of the counter knife 24. The paper strip is then completely cut. If the paper strip is only to be cut partially, the stroke of the control pin 62 must be reduced. For this purpose, a switching device 34 is provided, which is operated by hand on an operating button 36. The switching device 36 has an actuating element 90 which is guided in an elongated hole 88 and has a wedge-shaped flange 92 at its end facing the engagement lever 60. If the actuating element 90 is displaced in the direction of arrow B, the flange 92 engages in the movement of the engagement lever 60 in the radial direction in an inclined recess 94 formed thereon and guides the control pin 62 out of the control groove 64 before it reaches its maximum stroke Curve runout 80 reached, whereby the paper strip is only partially cut. The force of the spring 82 moves the knife 22 back into a position into its open position.

Figure 3 shows schematically a side view and a plan view of the cash register printer 10. In the print head holder 16, a print head 15 is inserted, the one Pressure abutment 17 faces. Between the print head 15 and the platen 17, a paper web (not shown) to be printed is guided, which is conveyed further via a transport roller 96 and a counter pressure roller 98 and is output from the opening 20 between the knife 22 and the counter knife 24. The movement of the print head 15 in the line direction is transmitted to the control disk 32 via a gear 102. The gearbox 102 has a drive gear 109 driven by a motor. The rotational movement of the drive gear 109 is transmitted to gearwheels 108, 110, the gearwheel 108 engaging in the ring gear of the control disk 32. The gear 108 drives a toothed belt 106 which is guided over a deflection roller 104 and moves the print head carrier 16.

The gearwheel 110 carries an angle coding disk 112, the coding of which is read by a sensor 114. The angle coding disk 112 and the sensor 114 form a rotation angle transmitter 116, the signals of which are evaluated for controlling the print head 15 in the line direction.

The gear 102 converts the linear movement of the print head 15 in the line direction into a rotary movement of the control disk 32. The gear ratio 102 is selected such that the control disk 32 does not quite complete a full revolution when the print head 15 moves in the line direction. The angular positions of the control disk 32 belonging to the different positions of the print head 15 are indicated in the top view (lower part of the figure) of FIG.

The knife 22 can assume three operating positions. The knife 22 shown in solid lines in the top view in FIG. 3 shows the open position O. The cutting edge 42 of the knife 22 can also be shown with a broken line Take positions T and V shown. In position V, the recess 44 slides fully over the cutting edge 40 of the counter knife 24. In this position V, the paper strip is cut completely. In the position T, the cutting edge 42 only slides up to the recess 44 over the cutting edge 40. In this position T a web of the paper strip remains, ie the paper strip is only partially cut through.

FIG. 4 shows a schematic view of the adjusting device from the side in a state in which the cutting device is activated. The print head 15 has a position which corresponds to an angular position of the control disk 32 of 310 ° (cf. FIGS. 3 and 2). The nose 76 of the control cam 74 has moved the bolt 70 to the right in this state, so that the control pin 62 engages in the control groove 64. During the subsequent rotation of the control disk in the opposite direction, the control pin 62 pivots upward in the radial direction of the control disk 32.

In Figure 5, the control disc 32 is in the angular position 130 ° (cf. the position of the print head 15 in Figure 3). The control pin 62 has reached its maximum stroke at a maximum distance from the center of the control disk 32, so that the knife 22 has cut through the paper strip completely (position V in FIG. 3). As can be seen in the lower part of FIG. 5, the control pin 62 is led out of the control groove 64 through the curve exit 80, so that the pivot shaft 54 can pivot back into the open position under the force of the spring 82.

FIG. 6 shows a schematic view of the adjusting device in a state in which the knife 22 executes a partial section. For this purpose, the print head 15 is moved into a position which corresponds to an angular position of the control disk 32 of 195 ° (cf. FIG. 3). The actuating element 90 of the switching device 84 is in a position displaced in the direction of the arrow B and engages with its flange 92 in the front end of the engagement lever 60 which is moved radially upward. As a result, the control pin 62 is released from the control groove 64 before it reaches its maximum radial distance from the center of the control disk 32. Because of the reduced stroke of the knife 22, this reaches a position (position T in FIG. 3) in which the paper strip is only partially cut.

FIG. 7 shows a schematic cross section through the knife 22 and the swivel bracket 52, which illustrates the mode of operation of the spring 82. This is arranged between knife 22 and swivel bracket 52 so that it strives to reduce the angle between knife 22 and swivel bracket 52. As a result, the knife 22 is pressed against the guide tracks 28 or the counter knife 24 during the cutting movement, as a result of which a smooth cut is produced. The guide elements 38 form a tapered slide bearing for the pin 50 of the swivel bracket. This type of bearing ensures precise guidance with little play and low bearing wear.

As shown in Figure 8, the spring 82 also has the effect of slightly deflecting the knife 22 between the guideways 28. The deflection can be, for example, 0.5 to 1 mm. This deflection creates a shearing, precise cut through the paper strip.

FIG. 9 shows that the guideways 28 are arranged in a plane that runs parallel to the upper surface of the counter knife 24, on which the knife 22 slides during cutting. The plane of the guideways 28 lies slightly below the surface of the counter knife 24. The distance a is, for example, 0.1 to 0.2 mm. This difference in height serves to compensate for manufacturing tolerances. The corners 22a of the knife 22 run obliquely upwards, whereby a ramp is formed. The ramp can be made by bending or grinding the corners 22a. These measures overcome the height difference between the plane of the guideways 28 and the upper surface of the counter knife 24 during cutting movements.

Claims (16)

1. Cutting device for cutting a print carrier in a printer, especially in a till printer, having a blade which is movable along at least one guideway against a fixed counterblade and which, in an open setting, frees an opening to allow the printer carrier to be passed through and, in a closed setting, has at least partially cut through the print carrier, the blade being able to be moved between the open setting and the closed setting by a pivot bracket which is driven by a plate cam, characterized in that the plate cam (32) has a control groove (64) running in the peripheral direction, the radial distance of which from the midpoint of the plate cam (32) increases over the rotational angle and in which an engaging lever (60) connected to the pivot bracket (52) can engage with its control pin (62) for a predefined rotational-angle compass, in that between the control pin (62) and the plate cam (32) there is disposed a blocking mechanism (66), which can lock the engagement of the control pin (62) in the control groove (64), in that on the plate cam (32) there is provided a control cam (74), which, upon rotation of the plate cam (32) about a predetermined angle of rotation, engages in the blocking mechanism (66) and unlocks the control pin (62), and in that an optionally actuatable switchover mechanism (34) is provided, which releases the control pin (62) from the control groove (64) once a predefined radial distance has been reached.
2. Cutting device according to Claim 1, characterized in that the pivot bracket (52) is rigidly connected to a pivot shaft (54) mounted rotatably on the frame of the cutting device.
3. Cutting device according to Claim 2, characterized in that the pivot bracket (52) is pretensioned by a spring (82) into a setting in which the blade (22) is in the open setting.
4. Cutting device according to one of the preceding claims, characterized in that the control groove (64) has, in a predetermined rotational-angle compass of the plate cam (32), a curved outlet (80), which, upon rotation of the plate cam (32), disengages the control pin (62) from the control groove (64).
5. Cutting device according to one of the preceding claims, characterized in that the blade (22), depending upon the radial distance of the control pin (62) from the midpoint of the plate cam (32), cuts fully or partially through the print carrier.
6. Cutting device according to one of the preceding claims, characterized in that the blade (22) has at least two guide elements (38), which are disposed at a distance apart on the side facing away from the cutter (42) of the blade (22), and in that the pivot bracket (52) engages in the guide elements (38) in order to adjust the blade (22).
7. Cutting device according to Claim 6, characterized in that the guide elements (38) are plastics bearings in which the journals (50) of the adjusting mechanism (52) engage, the journals (50) being mounted, preferably in sliding arrangement, between tips of the guide elements (38).
8. Cutting device according to Claim 6 or 7, characterized in that the cutter (42) of the blade (22) comprises two cutter segments, which run from the middle of the cutter obliquely forward and outward in the direction of the cutting motion.
9. Cutting device according to Claim 8, characterized in that the cutter has in the middle a recess (44) in a V-shape, the tip of which faces away from the counter-cutter (40).
10. Cutting device according to one of the preceding claims, characterized in that the blade (22) rests at its outer sides on guideways (28), which preferably consist of plastics material.
11. Cutting device according to Claim 10, characterized in that the guideways (28) are disposed in a plane running parallel to the face of the counterblade (24) on which the blade (22) slides during the cutting operation, the plane being a small distance (a) away from the face.
12. Cutting device according to Claim 11, characterized in that the outer corners (22a) of the cutter segments run obliquely upward such that, during the cutting motion, the blade (22) is guided onto the face of the counterblade (24).
13. Cutting device according to one of the preceding claims, characterized in that the blade (22) is guided under spring pressure against the guideways (28).
14. Cutting device according to Claim 13, characterized in that the spring pressure causes the blade (22) to sag slightly downward in a region between the guideways (28).
15. Cutting device according to one of the preceding claims, characterized in that the blade (22) and the counterblade (24) are stamped metal elements, which are made from thin spring-band steel.
16. Cutting device according to one of the preceding claims, characterized in that the counterblade (24) consists of a stable spring-band strip, which is held by a plastics part.

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