WO1994026529A1

WO1994026529A1 - Printer for line printing on at least one print medium

Info

Publication number: WO1994026529A1
Application number: PCT/DE1994/000399
Authority: WO
Inventors: Wilfried Dobring; Günter Baitz; Wolfgang Malke
Original assignee: Siemens Nixdorf
Priority date: 1993-05-10
Filing date: 1994-04-08
Publication date: 1994-11-24
Also published as: DE4315510C2; TW216409B; DE4315510A1

Abstract

A printer for line printing on at least one print medium has a print head that is moved back and forth in line direction along a predetermined path (L), driven by the rotation of a reversible motor, printing the print medium in the process. A feed system (27) advances the print medium by one predetermined line space. The motor is coupled with the feed system (27) by means of gears (64). The feed system (27) produces a line feed when the print head (15) has traversed a predetermined section of the path (L).

Description

Printer for line-by-line printing of at least one print carrier

The invention relates to a printer for line-by-line printing of at least one print carrier, with a print head which can be moved back and forth along a predetermined distance in the line direction by the rotation of a reversible motor and thereby prints on the print carrier, and with a feed device for feeding the Print carrier by a predetermined line spacing.

Such a printer is known, for example, from DE 35 11 386 AI and serves as a cash register printer for printing the receipt or for journal printing. The printhead of the known printer is arranged on a printhead holder which is driven by a motor Row direction is moved back and forth. A feed device contains a further motor which, after printing a line, rotates a transport roller by a predetermined angle of rotation which corresponds to a predetermined line spacing. The control of the printer controls the reversible motor of the print head and the motor of the feed device independently of one another by separate signals. The use of two motors and the associated control means that the hardware expenditure in the known printer is relatively large.

It is an object of the invention to provide a printer which consists of a reduced number of electromechanical components and the control of which is simple.

This object is achieved for a printer of the type mentioned at the outset in that the motor is coupled via a gear to the feed device which carries out a line feed when the print head passes at least a predetermined section of the line.

The invention is based on the consideration that printing operations are not to be carried out while traveling over the entire distance along which the print head is moved. When driving over sections of line without printing processes, the drive energy of the motor can therefore be used for the line feed. By connecting the feed device to the motor via the gearbox, a separate motor for the line feed can be dispensed with. Accordingly, the control can also be constructed more simply, since it only has to provide signals for a motor.

In the case of a printer which carries out printing operations only in one direction, for example when the Print head from left to right, only a section is to be provided along the line, preferably at the beginning or at the end of the line, within which the feed device executes the line feed. In bi-directional printing, ie printing operations are carried out in both line directions, two such sections must be provided along the route, for example at the ends of the routes outside the printing area on the printing medium.

In a preferred exemplary embodiment of the invention, the feed device contains a control disk which rotates as a function of the rotation of the motor and thus as a function of the distance traveled by the print head, the control disk actuating a ratchet mechanism which reaches a transport roller for the print carrier when the section is reached rotates a predetermined angle of rotation. By using the above-mentioned mechanical components, a simple construction of the printer is achieved, which is suitable for mass production at low costs.

It can further be provided that the control disk has at least one switching cam which actuates a ratchet lever which can be pivoted about a pivot axis and which transports a ratchet wheel by one tooth pitch via a transport pawl. The switching cam can be releasably connected to the control disk in predetermined angular positions. In this way, the section in which the line feed takes place can be adapted to the width of the print carrier. As a result, the overall printing speed can also be increased since the total length of the line can be kept small. Another embodiment of the invention is characterized in that at least two ratchet wheels are provided which, when actuated, rotate the transport roller through different angles of rotation, and that the clinch lever can be selectively engaged with one of the ratchet wheels by a switching mechanism. With this measure, the line feed can be changed from line to line. This is necessary, for example, when switching from an operating mode in which alphanumeric characters are printed to graphic mode, in which the line spacing must be selected such that the pixels of successive lines are connected to one another. The different angles of rotation can be set, for example, by different tooth pitch of the ratchet wheels.

The invention can also be used for printers which have a plurality of print carriers arranged side by side and which can be printed by the print head in a single movement along a line. For this purpose, each carrier has a pressure feed device, ^'executes when Überfah¬ ren an assigned portion of a Zeilenvor¬ thrust. This embodiment of the invention is preferably used for cash register printers which print a print medium for issuing receipts and a further print medium for temporary storage in the cash register printer (journal printing).

In another development of the invention, the feed device contains an adjusting device which actuates a cutting device for cutting off the print carrier when the printhead traverses at least one further section of the line. In the case of cash register printers, the print carrier for the receipt has to be cut either partially or completely so that it is light can be removed from the printer. The feed device fulfills a double function as a result of the aforementioned measures. On the one hand it executes the line feed when it passes over a certain section and on the other hand it actuates the cutting device which cuts the printing medium when it passes over a further section.

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

FIG. 1 shows a schematic view of a printer which is used as a structural unit in a cash register housing,

FIG. 2 shows a schematic, partially broken away top view of the printer according to FIG. 1,

Figure 3 is a schematic representation of the

Feed device for the line feed,

Figure 4 different sections along the

Distance that the print head travels during the reciprocating motion,

FIG. 5 shows the actuation of a ratchet mechanism by a control disk,

FIG. 6 the control disk with a switching mechanism for actuating various ratchet wheels,

FIG. 7 shows the control disk shortly before the switching mechanism is actuated, FIG. 8 shows a side view and a top view of the control disk after the switching mechanism has been actuated,

FIG. 9 the control disk with an adjusting device for actuating a cutting device.

Figure 1 shows a printer 10, which is designed as a unit for use in a till (not shown). Two side walls 12 hold cylindrical guide rails 14 arranged in parallel, between which a print head holder 16 is guided. The print head holder 16 can accommodate a print head which prints line-by-line color dots using the mosaic printing method. The print head holder 16 is moved back and forth on the guide rails 14 by a toothed belt 17 driven by a reversible direct current motor. The toothed belt 17 is firmly connected to the pressure carrier 16, so that various printing positions along the guide rails 14 can be controlled with high repetition accuracy by the rotation of the reversible motor.

The printer 10 includes a paper supply roll 18 for receipts and a paper supply roll 20 for journal printing. The paper of the paper supply rolls 18, 20 is guided past the print head along guides (not shown) and can be output via output chutes 22.

The movement of the toothed belt 17 is transmitted via a gear to a control disk 24 with a ring gear. This control disc 24 has a switching cam 26, which operates a ratchet mechanism 30, as will be explained in more detail.

In Figure 2, the printer 10 of Figure 1 is shown in a schematic, partially broken away view from above. The print head holder 16 is equipped with a print head 15. The printhead 16 can be moved back and forth by the motor along a distance L, and in its outer positions (the right outer position is shown in broken lines) it moves into recesses 32. The print head 15 can print a paper strip for receipts from the paper supply roll 18 as well as a paper strip for de journal printing from the paper supply roll 20 as it moves along the distance L. In order to be able to produce different line spacings for these paper strips, the printer 10 contains a feed device 27, 29 for each paper strip, the feed device 29 being provided with a further control disk 25. The paper is fed through transport rollers 34 and 36, pressing against the counter rollers 38. The longitudinal movement of the print head holder 16 is transmitted to the control disk 24 or 25 via a gear. The transmission ratio is selected so that the control disks 24, 25 move one turn of the print head holder 16 along the distance L. Execute 318 °, as indicated in Figure 2 on the left.

The control disk 24 actuates the ratchet switching mechanism 30, which contains a ratchet wheel 40 connected to the transport roller 34 with a number of teeth z = 9. The control disk 25 actuates a ratchet switching mechanism 42, which is optionally in engagement with a ratchet wheel 44 with the number of teeth z = 9 or a ratchet wheel 46 with the number of teeth z = 12. The ratchet mechanism 42 is connected to a switching mechanism 50, which engages in the optional one of the ratchet wheels 44, 46 causes, as will be explained in more detail. The switching mechanism 50 is actuated by a magnet 52, the armature 54 of which is biased into a rest position (shown in FIG. 2) by a spring 56. When the magnet 52 is energized, the armature 54 engages in a slide 58 which finally causes a changeover from one ratchet wheel 44, 46 to the other.

FIG. 3 shows a schematic side view of the structure of the feed device 27 for the line feed of the paper web on which the journal printing takes place. The paper web (not shown) is guided along a guideway 62 past a pressure abutment 60 which faces the print head 15. The movement of the print head 15 in the line direction is transmitted to the control disk 24 via a gear 64. The gear 64 contains gears 70, 72 and 74. The gear 72 is driven by a drive shaft 73 connected to the motor (not shown) . Transfer the rotary movement of the gear 72 to the gear 74 and the gear 70, which engages in the ring gear of the control disk 24. The toothed wheel 70 also drives the toothed belt 17, which is guided over a deflection roller 66.

The gear 74 carries an angle coding disk 78, the coding of which is read by a sensor 80. The angle coding disk 78 and the sensor 80 form a rotary encoder 76 which generates digital signals. The coding is carried out in such a way that when the print head 15 is displaced in the line direction by a print dot spacing (dot), a pulse is generated by the sensor 80. The control of the printhead along the distance L takes place depending on pulses which the angle encoder 76 emits. The pawl switching mechanism 39 has a pawl lever 82 which can be pivoted about a rotary shaft 84 fastened to the housing. The ratchet lever 82 moves along a circular path 85 a transport pawl 86 which engages in the teeth of the ratchet wheel 40. This is rigidly connected to the transport roller 34 and moves it by an angle of rotation which corresponds to a standard line spacing of 4.233 mm. When the switching cam 26 passes the pawl lever 82, the transport pawl 86 executes a lifting movement. As a result, the ratchet wheel 40 is moved further by one tooth pitch, ie a line feed is carried out.

FIG. 4 shows a schematic representation of the path that the printhead 15 travels during its line-wise back and forth movement. The print head 15 is shown with solid lines in its extreme right position and with dashed lines in its extreme left position. The distance between these two positions corresponds to the distance L. As it moves, the print head 15 travels the length PS of the paper chute in which the paper web for the receipt with the paper width PI and the paper web for journal printing with the paper width P2 are arranged. Only a part of these paper webs is printed with a line width Dl.

The distance L which can be traversed by the print head 15 is divided into different sections which are identified by location points 11 to 18 in FIG. These location points 11 to 18 correspond to angular positions a1 to a8 of the control disks 24, 25. The rightmost position of the print head 15 is defined as the zero position. Starting from this zero position, the print head 15 sets when moving in the direction of the arrow LL (counterclockwise rotation) 296 dots (296 dot) back until it reaches its leftmost position. The covering of this distance L corresponds to a rotation of the control disks 24, 25 by 318 °. The print head 15 prints in both line directions, ie during the counterclockwise rotation in the direction LL and during the clockwise rotation in the direction RL. Accordingly, a line feed must be provided at each line end. This line feed takes place in the section between the location points 11, 12 or 13, 14. To carry out the line feed in section 11, 12, the switching cam 26 is arranged on the control disk 24 in the area of the associated angular positions al to a2. This means that when the print head 15 rotates clockwise in the RL direction at a distance of 20 dot from the zero position (21 ° on the control disk 24), the ratchet mechanism 30 begins to switch. The line feed is completed at a distance of 10 dot (11 ° on the control disk 24) from the zero position. When the print head 15 runs counterclockwise in the direction LL, the ratchet mechanism 42 is actuated by the control disk 25 in sections 13, 14 at a distance of 269 dot (289 ° on the control disk 25) from the zero position. "The line feed is at a distance of 279 dot (300 °) completed.

The further switching operations sketched in FIG. 4 at the location points 15 to 18 relate to a cutting device for cutting off a receipt or the actuation of a pivoting lever for setting different line feeds. These switching operations are explained in more detail below.

In Figure 5, the control disc 24 is shown in a state in which the switching cam 26 has just pivoted the pawl lever 82. The transport pawl 86 has moved the ratchet wheel 40 further by one tooth pitch, ie has carried out a standard line feed. The Control disk 24 has an angular position of 11 ° with respect to the zero position.

6 shows the feed device 29 with the control disk 25 in the angular position 300 °. A switching cam 88 pivots a ratchet lever 90 about a pivot shaft 92, so that a transport pawl 94 moves the ratchet wheel 44 by one tooth pitch and thus executes the line feed. FIG. 6 also shows the switching mechanism 50, with which two different line feeds can be set. The link lever 90 is displaceable on the pivot shaft 92 in the direction of its longitudinal axis. An intermediate lever 98 which can be pivoted out of the plane of the drawing about an axis of rotation 96 engages in a pin 100 of the ratchet lever 90 and can move it on the pivot shaft 92 in such a way that the transport pawl 94 connected to it moves into another ratchet wheel 44 (not visible in FIG. 6). engages with tooth pitch deviating from the ratchet wheel 46. The intermediate lever 98 has a flange 99 which can be brought into engagement with the lifting cam 102 of a slide 58. The slide 58 can be moved along an elongated hole 104 (see also FIG. 2). At its end opposite the lifting cam 102, it has a pin 106 which projects through an elongated hole 108 in the control disk 25 on the other side. When the magnet 52 is actuated, the pin 106 is brought into engagement via the armature 54 with a switching shoe 110 which displaces the slide along the elongated hole 104.

The mode of operation of the switching mechanism 50 is shown in FIGS. 7 and 8. With an angular position of the control disk 25 of 230 °, the magnet 52 is actuated so that the switching shoe 110 swivels in the direction of the control disk 25 (see also FIG. 2). As can be seen in Figures 7 and 8, the pin 106 is at its passing (change of the angular position from 230 ° to 300 °) on the switching shoe 110 is deflected from its path 111, whereby the slide 58 moves in the direction of the intermediate lever 98, so that the lifting cam 102 comes into engagement with the flange 99 . The intermediate lever 98 is pivoted out of the plane of the drawing and thereby displaces the ratchet lever 90 on the pivot shaft 92. The transport pawl 94 is brought into engagement with the ratchet wheel 46 with a number of teeth z = 12. When the switching cam 88 passes, the ratchet lever 90 now actuates the ratchet wheel 46 via the transport pawl 94 and sets a reduced line spacing of 3.1747 mm, which is necessary for the graphics operation of the printer 10. It should be noted that the magnet 52 only has to be excited during the angular phase of 230 ° to 300 ° in order to switch over from the ratchet wheel 44 to the ratchet wheel 46. In the further angular phases, the magnet 52 does not have to be supplied with current. The slide 58 and the intermediate lever 98 are pretensioned by springs (not shown) in such a way that they move back outside the angular range from 230 ° to 300 ° into the starting position shown in FIG.

FIG. 9 shows a perspective view of the control disk 25, which controls a cutting device 110. The cutting device 110 serves to cut or cut through the paper strip for receipts and has a knife 112 which is moved against a stationary counter knife 114 to cut the paper strip. The knife 112 has two guide elements 118 which are mounted on pins 120 of a swivel bracket 121. The swivel bracket 121 is rigidly connected to a swivel shaft 123 which is rotatably mounted in the printer housing. The pivot shaft 123 is connected to a U-shaped bracket 125 which holds an engagement lever 122 which can be pivoted about the axis A. This has at its outer end a control pin 124 which is pressed elastically against the control disk 25 under spring pressure.

The control disk 25 has a control groove 126 running in the circumferential direction, the radial distance of which from the center of the control disk 25 increases over the angle of rotation. The engagement of the control pin 124 in the control groove 126 is prevented by a locking device 128, which covers the control groove 126 with a bolt 132 guided in an elongated hole 130. A compression spring 134 biases the bolt 132 in the direction of the pivot shaft 123.

When the print head 15 runs counterclockwise in the direction LL, a control cam 136, which is firmly connected to the control disk 25, shifts the latch 132 to the right at the location point 15 corresponding to an angular position a5 (distance 288 dot corresponding to 310 ° from the zero position in FIG. 4) and gives the control pin 124 free so that it can engage in the control groove 126. In the subsequent rightward rotation of the print head 15 in the direction RL, the control pin 124 is guided in the control groove 126, the engagement lever 122 executing a stroke along a control path 138. The knife is moved from the open position into a closed position via the swivel bracket 121, cutting through the paper strip (not shown).

The control groove 126 ends in a curve outlet 140, which guides the control pin 124 out of the guidance of the control groove 126. The knife 112 is connected to the swivel bracket 121 via a tension spring 142. The tension spring 142 pretensions the knife so that it is pulled back into its open position. Due to the force of the tension spring 142, the swivel bracket 122 pivots together with the engaging lever 121 back to its starting position, which corresponds to the open position of the cutting device 110.

The curve outlet 140 is arranged in an angular position of 130 ° with respect to the zero position of the control disk (121 dot corresponding to location point 17 and angle a7 in FIG. 4). At this angular position, the stroke of the knife 112 is sufficient to cut through the paper strip completely. If the paper strip is only to be cut, the stroke of the control pin 124 must be reduced. For this purpose, a switching device 144 is provided which is operated by hand. The switching device 144 has an actuating element 148 which is guided in an elongated hole 146 and has a wedge-shaped flange 150. When the actuating element 148 is displaced in the direction of arrow B, the flange 150 engages in the radial direction in the movement of the engagement lever 122 in a diagonally extending recess 152 formed thereon and guides the control pin 124 out of the control groove 126 (181 dot corresponding to the location point 16 and angle a6 in Figure 4) before it reaches the curve exit 140. The force of the tension spring 142 moves the cutting device 110 back into the open position in a state in which the paper strip is only partially severed.

Claims

Patent claims

1. Printer for line-by-line printing of at least one print carrier, with a print head which can be moved back and forth along a predetermined distance in the line direction by the rotation of a reversible motor and thereby prints the print carrier, and with a feed device for feeding the print carrier around a predetermined line spacing, characterized in that the motor is coupled via a gear (64) to the feed device which carries out a line feed when the print head (15) has at least one predetermined section (11, 12; 13, 14) of the extension - ke (L) runs over.

2. Printer according to claim 1, characterized in that the section (11, 12; 13, 14) is outside the printing area of the printing medium, preferably at the beginning and / or at the end of the path (L).

3. Printer according to claim 1 or 2, characterized gekenn¬ characterized in that the feed device (27, 29) contains a control disc (24, 25) which is dependent on the rotation of the motor and thus dependent on the distance traveled Printhead (15) rotates, and that the control disk (24, 25) actuates a ratchet switch (30, 42) when it reaches section (11, 12; 13, 14), which actuates a transport roller (34, 36 ) for the print carrier by a predetermined angle of rotation.

4. Printer according to claim 3, characterized in that the control disc (24, 25) at least one Has switching cams (26, 88) which actuates a ratchet lever (82, 90) which can be pivoted about a pivot axis and which transports a ratchet wheel (40, 44, 46) by one tooth part via a transport pawl (86, 94).

5. The device according to claim 4, characterized gekennzeich¬ net that the switching cam (26, 88) can be releasably connected in predetermined angular positions with the control disc (24, 25).

6. Printer according to claim 4 or 5, characterized gekenn¬ characterized in that at least two ratchet wheels (44, 46) are provided which, when actuated, rotate the transport roller (36) by different angles of rotation, and that the ratchet lever (90) can be brought into engagement with one of the ratchet wheels (44, 46) by a switching mechanism (50).

7. Printer according to claim 6, characterized in that the ratchet wheels (44, 46) are arranged side by side on a shaft connected to the transport roller (36), that the ratchet lever (90) opposite the ratchet wheels (44, 46) on a pivot shaft ( 92) is arranged displaceably in the direction of the longitudinal axis thereof, and that the switching mechanism (50), when actuated, shifts the pawl lever (90) into a position in which it engages in one of the pawl wheels (44, 46).

8. Printer according to claim 6 or 7, characterized in that the switching mechanism (50) can be actuated by a magnet (52).

9. Printer according to claim 8, characterized in that the magnet (52) one on the control disc (25) actuated in a predetermined angular position arranged slide (58) which displaces the pawl lever (90) via a pivotably mounted intermediate lever (98).

10. Printer according to one of the preceding claims, characterized in that the motor is a direct current motor, the rotational movement of which is detected by a rotary encoder (76) which generates digital signals, and in that a controller controls the print head (15). controls along the distance (L) depending on the signals of the rotary encoder (74).

11. Printer according to one of the preceding claims, characterized in that in the case of a plurality of print media which are arranged next to one another and are printed line by line by the print head (15), each print media has a feed device (27, 29) which, when passing over an associated Ab ¬ cuts a line feed.

12. Printer according to one of the preceding claims, characterized in that the feed device (29) contains an actuating device which, when driving over at least one further section of the line (L) through the print head (15), has a cutting device (110) for cutting off the Pressure medium actuated.

13. Printer according to claim 12, characterized in that the adjusting device has a control pin (124) which engages with a control groove (126) of the control disc (25) when it is rotated by a predetermined angle of rotation.

14. Printer according to claim 13, characterized in that the engagement of the control pin (124) in the control groove (126) is locked by a locking device, that a control cam (136) is provided on the control disk, which when the Control disk (25) engages in the locking device by the predetermined angle of rotation and unlocks the control pin (124).

15. Printer according to claim 13 or 14, characterized gekenn¬ characterized in that the control groove (126) extends in the U direction and its radial distance from the center of the control disc increases with increasing angle of rotation, and that the control pin (124) with a about a swivel axis (123) rotatable swivel bracket (121) is connected, which actuates a knife (112) of the cutting device (110).

16. Printer according to claim 15, characterized in that the control groove (126) in a predetermined angle of rotation of the control disc (25) has a curve outlet (140) which disengages the control pin (124) from the control groove (126), and that the swivel bracket (121) is prestressed by a spring (142) which moves the knife (112) into a rest position.

17. Printer according to one of claims 13 to 16, da¬ characterized in that a switching device (144) is provided which the control pin (124) when reaching a predetermined radial distance from the center of the control disc (25) from the control groove ( 126) triggers.

18. Printer according to one of claims 15 to 17, characterized in that the knife (112) depending on the radial distance of the control pin from the center of the control disk (25) cuts through the print carrier completely or partially.