DE3034121A1 - GRID PRINTER - Google Patents

Description

DIPL-PHYS. F. FINALLY germering Sept. 9, 1980 E / m

TELEPHONE: MÖNCHEN 84 36 38 DIPL.-PHYS. F. FINALLY, POST BOX, D-8034 SERMERINQ TELEX: 521730 pate D.

My file: S-4824

Applicant: Kabushiki Kaisha Seikosha, Tokyo, Japan

Raster printer

The invention relates to a raster printer in which the typeface is only assembled from individual, similar elements during the printing process.

Raster printers have in comparison to known printers with pre-formed Types (e.g. type wheel printer) have the advantage that not only symbols, but also, for example, graphic Representations can be printed at high printing speeds. Also, a variety of paper types can be used be printed on by suitable carbon paper. A common raster printer of this type is the wire printer, the has seven or more printing wires, the ends of which are arranged in rows in the feeding direction of the paper. A disadvantage however, such a wire printer is seen to be relatively complicated in construction and that a large number of items are required. Furthermore, the print head has a relatively large weight, so that the scanning mechanism and the voltage source must be designed according to this weight.

In other known screen printers, a screen printing roller is used on which a projection or a helical one Arrangement of projections are provided. The print hammer

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extends along the axis of the pressure roller and can against the Protrusions without performing a scanning movement in the direction Stop perpendicular to the feed direction of the paper to be printed. Therefore, to form a letter such as consists of a dot matrix of seven rows and five columns, the paper is fed seven times so that the Printing speed too slow for most practical purposes is. Furthermore, since the stop point between the print hammer and the projections on the print roller during the rotation of the print roller shifts successively in the lateral direction, the print hammer experiences a relatively large twist when it strikes against a projection at the end of the pressure roller. This results in a relatively unstable mode of operation. Furthermore, the practically possible length of the cross arm of the print hammer is limited and thus also the number of symbols that can be used with Can be printed using a single print hammer. To increase Due to the number of symbols per line, it is therefore necessary to provide several print hammers. *

It is therefore the object of the invention to provide a raster printer of the type mentioned at the outset while avoiding it as far as possible To improve the disadvantages and difficulties mentioned so that on the one hand it has a reduced size and a reduced weight has, so that it can be produced cost-effectively, and that on the other hand, the printing of symbols, graphic representations and high-speed printing images. Furthermore, it should be achieved that the power requirement for driving the raster printer is as low as possible.

In a raster printer of the type mentioned at the outset, this object is achieved according to the invention by the subject matter of claim 1. Advantageous further developments of the invention are the subject of subclaims.

In summary, therefore, are essential features of a raster printer according to the invention to see that only a single stop element is provided on the print head, and that the opposite the printhead arranged pressure roller has along its surface a number of cell-shaped projections which run essentially parallel to the axis thereof. Each of the pre

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Jumps can be brought into a suitable position in front of the stop element will.

The invention is to be explained in more detail, for example, with the aid of the drawing will. Show it:

Fig. 1 is a schematic front view of a raster printer according to the invention;

a sectional view along the line II-II in Fig. 1;

an enlarged view of a slotted disc for a Line identification;

an enlarged view of a slotted disc for a Column evidence;

a block diagram of a control circuit for the drive device a raster printer according to the invention;

6 shows a time diagram for explaining the mode of operation of the drive device ;

FIG. 7 shows two letters printed out with the aid of the stop element of the raster printer in FIG. 1; FIG.

FIG. 8 is a partial view of a modified version compared to FIG. 1 Embodiment of a raster printer according to the invention;

Fig. 9 is a sectional view taken along the line IX-IX in Fig. 8;

Prop. Fig. 10 is a front view of the print head of the embodiment in Figures 8 and 9;

11 shows a schematic representation of a further exemplary embodiment of a raster printer according to the invention;

FIG. 12 is a sectional view taken along the line XII-XII in FIG. 11; FIG. and

FIG. 13 is a front view of the print head of the raster printer in FIG. 11.

The following is the first embodiment according to the invention will be explained in connection with Figs. As can be seen from FIGS. 1 and 2, a pressure roller 1 is on a shaft

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2 and can be rotated essentially continuously in the direction of the arrow in FIG. 2 in a clockwise direction. In this embodiment the pressure roller 1 has a length which corresponds essentially to the width of the paper 17 to be printed. at of the illustrated embodiment are 12 rows of protrusions

3, each line extending parallel to the axis of the platen. A print head 4 is opposite to the platen 1 arranged such that it is displaceable in the axial direction of the pressure roller 1, that is, perpendicular to the feed direction of the Paper 17.

The print head 4 is arranged on a carriage 5, which is slidably displaceable along guide rails 6, 7 and not from one magnetic material with a light weight. A print hammer 8 is used to form points on the paper 17 in cooperation with the projections 3. The print hammer is against the projections struck with the aid of an electromagnetic drive device 9 which is arranged on the carriage 5.

In the following, the training of the pressure hammer 8 and the electromagnetic Drive device 9 will be explained in more detail. On the print hammer 8, a drive spring 10 is provided, the lower one End is attached to the carriage 5 and at the upper end of a stop element 11 is arranged. The stop element 11 extends essentially in the same direction as the feeding direction of the paper 17, so that the stop element has an opposite one Crossed projection 3. The length of the stop element is only slightly greater than the height of the letters to be printed.

The electromagnetic drive device 9 has a pot-shaped Magnet body with "an outer magnetic pole 12, a strong Permanent magnet 13, which consists for example of samarium cobalt and is arranged on the bottom of the pot-shaped magnet body, and an inner magnetic pole 14 arranged on the front side of the permanent magnet 13. There is also a movable coil 15 attached to the leaf spring 10 and arranged in the magnetic gap between the magnetic poles 12, 14. Extends in front of the stop element 11 an ink ribbon 16. The paper 17 to be printed is in the direction of the arrow in FIG. 2 through the gap between the ink ribbon 16 and the pressure roller 1 advanced and thereby guided by guides 18,19

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guided.

A shaft 20 in Fig. 1 is driven by a motor, not shown. The shaft 20 carries a slotted disc 21 and a
Pinion 22. The pinion 22 meshes with a gear 23 which is attached to the
Shaft 2 of the printing cylinder is attached. There is one on shaft 2
Slotted disc 24 arranged. A detection device 25, 26 is assigned to each of the slotted disks 21, 24, each having a light-emitting element and a light-receiving element,
which elements are opposite in the area of the opening in the
Detection device are arranged / which opening protrudes the slotted disc in question.

As can be seen from FIG. 3, in this exemplary embodiment three groups 27 of slots 28 are arranged at equal distances from one another along the circumference. The number of slots
28 in each group 27 corresponds to the number of rows M of the dot matrix of a letter, which matrix consists of M rows and N columns. In the illustrated embodiment, each
Group seven slots 2 8 provided.

The slotted disk 24 has in the manner shown in FIG
Slots 29 arranged at equal intervals in the circumferential direction
on. The number of slots 29 corresponds to the number of projections 3 on the pressure roller 1 on which in the illustrated
Embodiment twelve projections 3 are provided.

The detection devices 25, 26 generate a line detection signal b and a column detection signal c as shown in Figures 6, B and 6C is.

The slotted disk 24 also rotates by 30, while the slotted disk 21 rotates by 120 °, so that the two detection devices
Generate pulses with a pulse rate ratio of 7: 1. That's why
In this embodiment, the reduction ratio between the pinion 22 and the gear 23 is 1/4. The line detection signal b is a signal having a cycle which consists of seven line detection pulses Pb1, ... Pb7, which are each equally spaced from each other. The line position of the dots is determined by the relevant line detection pulses Pb1 ... Pb7. The line detection pulses are generated when the protrusions 3
on the printing roller 1 in Fig. 2 in which one of the seven lines

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speaking rotational position are brought. The column detection signal c serves to verify the column of the dot matrix. Every column detection pulse Pc is generated immediately before the generation of a line detection pulse Pb.

The print head 4 is driven with the aid of a drive device, not shown slidable along the guide rails 6.7. The speed of movement of the print head 4 during the printing process when moving from a left starting position to the right in Fig. 1 depends on the rotational speed of the pressure roller 1 in such a way that the print head 4 moves by a distance corresponding to N columns (Fig. 7), while the print roller 1 executes a half revolution.

As can be seen from Fig. 7, the stop element 11 of the printing hammer 8 has a length that is at least the height of the to be printed Sign corresponds. The stop member is inclined at an angle θ to the feeding direction of the paper. This angle is in Determined as a function of the scanning speed of the print head 4. In the illustrated embodiment, this is Angle about 7 to 8 °. The reason for the inclined arrangement of the stop element 11 will be explained later.

The movable coil 15 shown in Fig. 2 is connected to the drive control circuit connected, an embodiment of which is shown in FIG. This control circuit contains a character generator 30, a shift register 31, a column address counter 32, a buffer circuit 33, a driver circuit 34, a counter 35, AND gates 36-40, an OR gate 41, delay circuits 42-45 and flip-flop circuits 46, 47. The column address counter 32 generates an output signal S corresponding to the count by which the column of the character generator 30 is determined. The column address counter 32 generates output signals h and k. The output signals h and k initially have the logic value "1" and "0" until the number N of the column of the dot matrix, for example the fifth column, is counted. Then these signals are set to "0" or "1" inverted. The output of the counter 35 becomes "0" "1" is inverted when the number of rows M of the dot matrix, for example 7, is counted. After a delay time, which is determined by the delay circuit 44, it is reset to "0".

1 3 0 0 U / 1 1 8 0

A terminal Tb in Fig. 5 is connected to the Kachweiseinrichtung 25 in Fig. 1, UNAE a terminal Tc is connected to the detection means' .. 2 6 in Fig. 1 * A terminal Te receives a wax Weis signal ε in Fig _t 6E ,, that determines the print start position. The flip-flop circuit 46 is set by the rise of the detection signal e and reset by the fall of the column detection signal c. The flip-flop circuit 47 is set by the rise of a signal m from the AND gate 36 and reset by the fall of a signal 1 from the AND gate 39 =.

The operation of this printer is explained in more detail below will. A printing process is carried out when the print head 4 has moved from the starting position at the left end of the print roller 1 in FIG is moved to the right. First, the drive motor of the printing roller is switched on by the start signal a in Fig. SA, so that the Drive shaft 20 rotated in Fig. 1 «As a result, the shaft 2 is rotated via the pinion 22 and the gear 2 3, so that the pressure roller 1 rotates continuously in the direction of the arrow in FIG. 2 at a predetermined rotational speed. The verification facilities 25 and 26 then start, line detection signals b and column detection signals c corresponding to FIGS. 6B and 6C as a function of the rotational position of the slotted disks 21, 24 in FIGS. 3 and 4.

When the drive signal d in Fig. 6D is generated for the printhead is, the print head 4 is moved from its starting position to the right. After the printhead is a predetermined distance out of its Has traveled the starting position, the detection signal e for the printing start position is made with the aid of a sensor, not shown generated. The detection signal e in FIG. 6E sets the flip-flop circuit 46 in FIG. 5 so that its output signal f is inverted to "1" as shown in Fig. 6F. This output signal f becomes one of the input terminals of the AND gate 36 supplied through the OR gate 41, so that the AND gate 36 is opened.

The characters supplied, for example, by a process computer, the Letters, numbers or other symbols are first stored in the character generator 30 in the form of a dot matrix. The character generator 30 generates column signals depending on the one selected by the column address signal S

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ORIGINAL INSPECTED

ΊΟ

- * - 303 * 121

Address. Since this state of the count of the column address counter 32 is nujI, the character generator 30 generates the matrix signal of the first column of the dot matrix of the character in accordance with the transmitted data. The outputs h and k in Figs. 6H and 6K from the column address counter 32 then become "1" and "0", respectively. Then the pulse Pd of the column detection signal c is generated by the detection device 26 in FIG. 1 and supplied to the AND gate 36 in FIG. 5, so that the AND gate 36 emits the output signal "1". The flip-flop circuit 46 is reset by the fall of the pulse Pd, so that the output signal from the flip-flop circuit 46 is "0". A pulse Pm1 then occurs in the output signal m of the AND gate 36, which pulse determines the first column of the dot matrix. The matrix signal of the first column of the to the character generator 30 in Fig. 5 the transmitted data is stored by the shift register 31 and the F.lipfiopschaltung 47 is reset by the Anstieb the pulse PMI so that the Aasgangssignal r of flip-flop ³ 7 on the VZert " 1 "reached. Then, the detector 25 in Fig. 1 generates line detection pulses Pb1-Pb7 as shown in Fig. 6D. These pulses Pb1-Pb7 are applied to the AND gate 37 in ^ ir /. 5 ". Since the level of the two input terminals of the AND circuit 37 is" 1 ", the line detection pulses can pass through the AND gate 37. Then, the matrix signal stored in the shift register 31 is read out in response to the line detection pulses Pb1-Pb7 and is supplied to one of the input terminals of the AND gate 38. Simultaneously with this read-out operation, the pulses Pb1 Pb7 are supplied to the other input terminal of the AND gate 38 via the delay circuit 43. Therefore, drive signals corresponding to the matrix signals of the first column appear in the output signal η of the AND gate 38 with a slight phase delay compared to the generation of the pulses Pb1 - Pb7. For example, when the letter A is transmitted to the character generator 30, the AND gate 38 can generate drive pulses P31, P41 ... P71 (Fig. 6N) Driving pulses are generated when any of the projections 3 of the continuously rotating pressure roller e 1 is in a position corresponding to the third, fourth row, etc. in front of the stop element 11 in FIG. 7. The stop element 11 inclined by the angle θ moves continuously in a straight

1 3 Q 0 U / 1 1 8 0

ORIGINAL INSPECTED

ΛΛ

direction of the arrow in Fig. 7 during the scanning movement of the print head 4. When drive pulses P31, P41 ... P71 are generated, the projections 3 and the stop element 11 cross one another successively in the third, fourth .... seventh line of the first column.

When the AND gate 38 in Fig. 5 generates the drive pulses P31, P41 ... P71, the driver circuit 34 is through the relevant Drive pulse activated, so that the coil 15 current pulses are supplied. This moves the coil 15 to the left in Fig. 2, so that the stop element 11 abuts against the projection 3 of the rotating pressure roller 1 and a point of the first Column of the letter A is printed out on the paper 17 in a position shown in FIG.

The following is intended to explain why the stop element 11 is arranged inclined. As already mentioned, the stop element 11 is actuated while it is to the right over the paper in Fig. 7 is moved. If the stop element 11 would cross the projections 3 at right angles, this would result because of the rotation the pressure roller 1 with dots of successive lines a certain shift in the relevant column of dots, so that an acute-angled arrangement of the points of this column would result relative to the conveying direction of the paper. Like from the Embodiment in Fig. 7 can be seen, however, is the stop element inclined at an angle θ of about 7 to 8 so that the dots of each column are precisely aligned in the direction of feed of the paper are. This angle can vary according to the way the letters are written. When the letters for example, have an inclined position, the angle θ is selected to be correspondingly larger.

In the following, the further method of operation will be explained. When the input to the shift register 31 in Fig. 5 by the pulse Pm1 of the. AND gate 36 is completed, the pulse Pm1 is counted by the column address counter 32 via the delay circuit 42. The count of the counter 32 is then increased by one unit, so that the character generator 30 matrix signals for the second Column created. The line detection pulses Pb1-Pb 7 occurring at the output of the AND gate 37 are counted in the counter 35.

130ÖU / 118Q-

When the count reaches 7, i.e. when a column is printed out is, the output signal g of the counter 35 becomes "1" as off 6G can be seen. Then the output signal becomes h of the column address counter 32, which is the input signal to one input of the AND gate 40, is held at the value "1" so that the output signal j of the AND gate 40 becomes "1", which is supplied to the AND gate 3B through the OR gate 41. The AND gate 36 generates a pulse Pm2 (Fig. 6M) which determines the second column of the matrix of dots, and the counter 35 is activated by the action the delay circuit 44 is reset. Then the dots in the second column are printed out in the manner described above. The points of the second column are formed by the interaction between the stop element 11 and the next one Protrusion compared to protrusion 3, which was used to form the points of the first column. This way of working is continued until the letter A shown in Fig. 7 corresponding to a dot matrix with seven lines and five Columns is printed out.

When the column address counter 32 in FIG. 5 reaches the count five, its output signals h and k are inverted to "0" and "1", respectively. Therefore, after a printing operation for the fifth column, the output pulse Pg5 of the counter 35 causes the AND gate 39 to emit an output pulse P1 in FIG. 6L. The column address counter 32 and the flip-flop circuit 47 are reset by the fall of this output pulse P1. Therefore, the output signals h and k of the column address counter 32 become "1" and "0", respectively, so that the output signal r of the flip-flop circuit 47 becomes "0". The pulse Pl becomes a pulse Pl through the delay circuit 45 ¹ delayed as shown in dashed lines. This delayed pulse is supplied to the AND circuit 36 through the OR circuit 41. When the AND circuit receives a column detection pulse PcO after the completion of the pressing of a letter, the AND circuit 36 does not output a pulse as shown in Fig. 6M, but generates an output pulse Pm1 when the next column detection pulse Pd is received. The next letter is then printed after a free space has been formed corresponding to one column, as can be seen from FIG.

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The print hammer 8 is at a high frequency of 1800 Hz or more driven during the continuous printing of the dots, so that the response oscillation frequency is the resonance frequency the leaf spring 10 approaches.

The column detection signal c can be determined with the aid of the line detection signal b are generated by means of a purely electrical circuit, which the function of the interaction of slotted disc 24 and the detection device 26 takes over. For example, the pulse spacing between the successive pulses Pb1-Pb7 can be detected by a clock or the like means so that the above-mentioned column detection pulse Pc is electrically is generated between the pulses Pb7 and Pb1 when a long pulse interval is detected.

Furthermore, modified constructions of the printing hammer 8 and the electromagnetic drive device 9 can also be used.

In the second embodiment shown in FIGS. 8-10 For example, the platen 101, the shaft 102 and the protrusions 103 are formed as in the first embodiment. With this one Embodiment, however, the print head has a different design. An inner columnar magnetic body 105 is provided on its rear side with a radially projecting disk part 105a. An annular permanent magnet 107 is between the disk part 105a and an outer magnetic pole 106 pinched. These parts are glued together at their connection points. On the front of the outer magnetic pole 106 are a non-magnetic Spacer ring 108 and a cover 109 fastened by screws 110 (Fig. 10). In the interior of the cover 109 is a plate-shaped print hammer 111 slidably displaceable in Guide grooves 112, 113 arranged in the inner wall of the cover 109 are formed. A movable coil 114 is wound around a tubular coil core. The bobbin 115 is attached to the rear end of the print hammer 111 and is in the Air gap arranged between the inner magnetic pole 105 and the outer magnetic pole 106. The print hammer 111 has a stop element 116, which the stop element 11 in the first embodiment is equivalent to. The stop element extends through a window 117 in the cover 109 so that it is opposite

1300U / 118Ö

a respective one of the protrusions 103 of the platen, as in the first embodiment, and the respective protrusion crossed over. The print hammer 111 is biased backwards by a coil spring 118 which is arranged in the cover, so that the print hammer 111 lightly against the face of the spacer ring 108 is pressed in its rest position. The print head 104 is provided with a holder 120 which is attached to the lower part of the outer magnetic pole 106 is fixed by screws 119. The holder 120 has wings 121 from opposite sides of the inner magnetic pole, the outer magnetic pole 106 and the permanent magnet 107 protrude. The printhead 104 is not on one shown trolley with the aid of the holder 120 so that it can be axially with the aid of a pulse motor or the like Direction of the pressure roller 101 is displaceable. The paper (not shown) and the ribbon run through the gap between the stop member 116 of the print head 104 and the platen 101 as in the first embodiment. The way of working is also the same essentially that in the first embodiment.

In the third embodiment shown in FIGS. 11-13 is a carriage 201 made of a non-magnetic light material slidable along guides 203 attached to opposing side panels 202. One on the carriage 201 Attached print head 204 has a print hammer 206 and an electromagnetic drive device for driving it. Of the Print hammer 206 consists of a leaf spring 205 that is triangular in shape is formed and is attached to the carriage 201 at its lower end with a pin 205a. On the opposite free A stop element 205c is arranged at the end of the leaf spring 205b. The electromagnetic drive device 2O7 consists of an inner magnetic pole 208, which is attached to the carriage 201, a permanent magnet 209, which is attached to a rear disk-shaped Part of the inner magnetic pole 208 is attached, an outer magnetic pole 210, which is attached to the permanent magnet 209, as well from a movable coil 211, which is in the air gap between the Magnetic poles 208, 210 are arranged and attached to the leaf spring 205. The construction of the printhead 204 is therefore largely the same the first embodiment.

130ÖH / 1 180

-IS

In this third embodiment, however, the pressure roller 212 has the following special features. The pressure roller 212 has a short length regardless of the number of characters to be printed. In this embodiment, only such a length is the Platen 212 is provided which is required to print a single character. The platen 212 is slidable on the Shaft 2.T3 arranged, which is rotatably mounted in the side plates 202. The platen 212 rotates together with the shaft 213, because it has a non-circular cross-section, which in the illustrated embodiment is rectangular is. The platen 212 has, for example, twelve linear protrusions 214 integrally formed therewith. the Pressure plate 212 is arranged between fork-shaped arm parts 217 of a carrier 216 and has sleeves 215 which are rotatable the arm parts 217 are arranged. The carrier 216 is shown in FIG. 11 Slidable left and right but cannot rotate about sleeves 215 because one was attached to side plates 202 Support shaft 219 protrudes in a recess 218 in a rear part of the carrier 216.

As can be seen from Fig. 11, there is a gear 220 and a pinion 221 is attached to the end of shaft 213 that protrudes to the right from side plate 202. The gear 220 meshes with a pinion 22 3, which is attached to the output shaft of a drive motor 222. A gear wheel 225 meshing with the pinion 221 is rotatable a shaft 22 4 which is attached to the side plate 202. A pinion 226 is also freely rotatable on the shaft 224 and arranged displaceably in the axial direction. The gear 225 and the pinion 226 are connected to each other via clutch gears 227 coupled integrally formed therewith. The clutch gears 227 can with the help of an electromagnetic Pistons are engaged or disengaged. Shafts 228, 229 are also attached to the side plates 202. At The shafts 228, 229 each have a drum 230 or 231 rotatably mounted. Gears formed in one piece with the drums 230, 231 232, 233 mesh with the pinion 226. A pull cable 234 engages the carriage 201 and a pull cable 235 engages the carrier 216. These pull ropes are wound onto the relevant one of the drums 230, 231 via rope pulleys 236, 237. The drums 230, 231 can

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are driven in opposite directions. Since the pulling ropes 234, 235 around the drums 230, 231 in opposite directions Directions are wound, the winding or unwinding of these drums is synchronous.

A return spring 238, 239 is fastened to the left end of the carriage 201 and the carrier 216. On the pinion 223 is a Slotted disk 240 arranged, like the slotted disk 21 at the first embodiment is formed. The outer circumference the slotted disk 240 protrudes into an opening of a detection device 241 before and the synchronization of the printing process is carried out as in the first embodiment with the aid of the detection signal achieved by the verification device. The paper to be printed 242 and an ink ribbon 2 43 are between the print head 204 and the Pressure roller 212 arranged.

When the carriage 201 and the carrier 216 are in the starting position at the left end in FIG. 11, the gears 232, 233 via the pinion 223, the gear 220, the pinion 221, the gear 225, the clutch gears 227 and the pinion 226 driven as soon as the drive motor 222 is energized. Then the drums 2 30, 231 and the lift cords 234 rotate, 235 are wound on the drums, so that the carriage 201 and the support 216 from the _s initial position to the right are moved at a predetermined speed, whereby the relative position illustrated is maintained.

During this movement of the carrier 216 together with the platen 212 to the right, the pressure roller is continuously rotated clockwise in FIG. 12 by the shaft 213. Printing takes place in the same manner as in the first embodiment during the synchronized movement of the print head 204 and the Print roller 212. As soon as a line has been printed out, a feedback signal is fed to the piston of the clutch gears 22 7. Then the clutch gears 227 are disengaged, see above that the carriage 201 and the carrier 216 return to the starting position by the action of the return springs 238, 239.

In this embodiment, the protrusions 214 on the platen 212 may have a length just sufficient that a crossover with the stop element 205c can take place. the end

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At

- i * - 303A12T.

For practical reasons, however, it is more appropriate to use a length of the projections 214 to be provided, which corresponds essentially to the width of a character. It is also possible to use a helical To use a drive mechanism known per se to drive the carriage 201 and the carrier 216. It. it is also possible mutually independent drive devices for the carriage 201 and the carrier 216 to use.

In the three exemplary embodiments described, the pressure rollers 1,101 and 212 are driven in the reverse direction. In such a case, the stop elements 11, 116 and 205c, in contrast to the illustrated embodiments inclined in the opposite direction. arranged. It is further possible to form the stop elements 11 and 205c in one piece with the leaf springs 10 and 205b, respectively.

With raster printers of the type described, it is therefore possible Print letters, numbers, symbols, graphics and images with the help of a single print hammer. Furthermore can the size and weight of the printhead can be reduced because it consists of a reduced number of individual parts, so that the print head is driven by a motor with reduced drive power can be driven. There is also the inertial mass of the print hammer is less, the print hammer can be driven faster with reduced power requirements. The speed of work of the print hammer and the service life of the printer can also be increased if the print hammer has a cantilevered leaf spring has, at the end of which the stop element is attached, because in such an arrangement there is no friction loss existing part is present. In a construction where the pressure roller is moved together with the printhead, a minimum axial length of the pressure roller can be provided, whereby not only the production is simplified, but also detrimental effects on the print quality due to deformations and bending of the pressure plate, which is designed as a roller, can be avoided. Also the number of characters that can be printed on a line is not limited by the length of the print roller, so that the maximum printable number of characters per line is as desired Way can be increased within wide limits. The described-

1300U / 11ÖÖ

1*

benen printers can also be produced more easily and cost-effectively will.

1300U / 1 1

Claims (9)

Claims 1. Raster printer, characterized in that the printing roller {1; 101; 212) has a number of linear projections (3; 1O3; 214) which are essentially
extend parallel to its axis so that the print head (4; 104; 204) is displaceable perpendicular to the feed direction of the paper (17) to be printed and a single print hammer (8; 111; 2O6) with a stop element (11; 116; 2O5c), in front of the relevant projections in a crossover position arrive, and that an electromagnetic drive device is provided for driving the print hammer. 2. Raster printer according to claim 1, characterized in that the electromagnetic drive device has a movable coil arranged on the print hammer (15; 115; 211), and that a magnetic device for
Generation of a magnetic flux penetrating the coil is provided. 3. Raster printer according to claim 1 or 2, characterized in that the stop element (11; 2O5c) is arranged at the free end of a leaf spring (1O; 2O5), the
the other end is attached to the printhead. 130 014/1 180 4. Raster printer according to claim 1 or 2, characterized in that that the print hammer (111) is formed in one piece with the stop element (116) and in guides (112,113) is arranged to be longitudinally displaceable. 5. Raster printer according to one of the preceding claims, characterized in that the stop element has a length slightly greater than the height of the character to be printed. 6. Raster printer according to one of the preceding claims, characterized in that the stop element is inclined at a predetermined angle to the feeding direction of the paper. 7. Raster printer according to one of the preceding claims, characterized in that the printing roller (212) and the print hammer (204) together displaceable in a direction perpendicular to the feeding direction of the paper (242) are. 8. Raster printer according to claim 7, characterized in that that the pressure roller (212) has a length which is approximately equal to the width of a character to be printed. 9. Raster printer according to claim 7 or 8, characterized in that that the pressure roller (212) and the print head (204) can be driven by a common drive device are. 1300U / 1 180