EP0052066A2 - Matrix printer and wire print head therefor - Google Patents

Abstract

In the case of a matrix printer with a needle print head that can be moved in print passes, which is in the printing position opposite a record carrier that can be moved between print passes, with an adjustable mouthpiece in which the needles are guided in bores in columns, the basic position of the mouthpiece is for quick writing and, if necessary, deviating positions are in reciprocating print passes are provided for fine writing. In order not to relate the smallest step of the paper movement to half the needle spacing in such a matrix printer, because it is relatively difficult to move the paper by such small distances, it is provided that with the adjustment of the mouthpiece (6; 6a, 6b) in Lengths between two consecutive printing needles (2) in a needle gap (1), i. H. With a mechanical, finer division of the matrix in character height (3a), at the same time, an electronic, finer division of the matrix in character width (3) is connected, the ratio of the division in character height and in character width for quick writing and for fine writing at least 0.4: 1 is or greater.

Description

The invention relates to a matrix printer with a needle print head which can be moved in print passports and which is located in the print position relative to a record carrier which can be moved between print passes, with an adjustable mouthpiece in which the needles are guided in bores in columns, the basic position of the mouthpiece for quick writing and positions which deviate therefrom if necessary are provided in reciprocating print passes for fine writing.

Such a matrix printer serves the purpose of producing different printing qualities of the characters at different writing speeds. In general, a matrix printer only ever performs one task, namely printing out characters at high speed (but the print quality of the characters is lower) or printing at high quality (but the speed of writing is lower).

It is known (DE-OS 26 32 293) to move a movable vertical pressure needle column parallel to a second fixed pressure needle column. The offset serves to solve the task of designing a dot matrix printer either for high-speed printing or for the generation of characters of high print quality. The offset with the size zero is selected for the fast writing, while an offset of the mouthpiece greater than zero is set for the writing. If one follows the basic idea of the known solution, it is found that only an improvement in the conditions in the direction of the needle gap occurs and that the type of paper advance is also unsolved.

The present invention is therefore based on the object of providing a matrix printer with an associated needle print head which does not relate the smallest step of the paper movement to half the needle spacing, because it is relatively difficult to move the paper by such small spacings.

The printhead to be created for fine writing or quick writing should also be usable as desired and should furthermore improve the quick writing and / or fine writing.

The object is achieved in that with the adjustment of the mouthpiece in layers between two consecutive pressure needles in a needle gap, ie with a finer mechanical division of the matrix in character height, at the same time an electronic finer division of the matrix in character width is connected, the ratio of the division is at least 0.4: 1 or greater in character height and in character width for quick writing and for fine writing. The invention accordingly permits a combined application of the method to refine the matrix both in the direction of the needle gap and in the direction of writing, transversely to the direction of the career of the recording medium. At the same time, the invention solves the problem of paper feed, which can take place outside the print movement of the print head. The paper can thus be held in place during printing. All of these influences work together to create a faster and more beautiful font in combination based on the theory of the invention. In addition, only one (off changeable) printhead required. In the present case, the electronic fine division can preferably make use of two separate character generators, the controller (for example a microprocessor with program memory) alternately calling up the finely or roughly divided clocks.

In an embodiment of the invention, the matrix is refined from 9 x 7 to 18 x 40, 18 x 28 or 36 x 40 in the case of an at least two-part mouthpiece with needle gaps.

The further problem of redesigning a known needle printhead for a matrix printer, which is equipped with the appropriate number of printing needles, each of which an electromagnet is assigned, is solved according to the further invention in that the adjustable mouthpiece is connected to an organ transmitting the adjustment drive force and that this organ is assigned to the adjustment drive directly or with the involvement of an intermediate element. It has been shown that there is just room for this organ, possibly for an intermediate member and an adjustment drive, in such needle printheads.

This desired use of space or space distribution for the narrow and easy-to-hold needle printheads is also supported by the fact that the organ transmitting the adjustment drive force, possibly the intermediate link and the adjustment drive (s), are arranged in the front area of the print head and are enclosed by a housing.

A practical embodiment for the drive design consists in the fact that the organ transmitting the adjusting drive force from a ge on the printhead base frame stored, pivotable lever with pole faces, which are opposite the poles of a magnet that can be switched on and off.

A further alternative for the design of the drive transmission is further proposed in that the organ transmitting the adjusting drive force consists of a shaft rotatably mounted on the print head base frame, which carries the intermediate piece, which is arranged with mutually facing pole faces opposite the magnetic poles of two mutually associated magnets, the Shaft is connected to two mouthpieces by means of a parallelogram linkage.

In a further embodiment of the invention it is provided that the adjustment drive consists of one or two electromagnets.

When using two interacting electromagnets, it is advantageous if the intermediate member is designed in the form of a rocker.

On the other hand, the invention also allows the intermediate member to be designed in the form of a pointer.

A further embodiment of the invention is that the organ connected to the mouthpiece extends approximately in the direction of the needle bundle and can be moved back and forth by means of the adjustment drive transversely to the direction of flight of the printing needles by a fraction or a multiple of a needle distance measured in the direction of movement.

Here, a further practical embodiment of the invention results from the fact that the adjustment drive for the back and forth movement of the organ by means of a drive in both directions of rotation, transverse to the direction of flight of the pressure needles extending, axially fixed screw spindle is formed.

A corresponding choice of thread for the screw spindle, which should not be subject to excessive escapement, the rotary drive for the screw spindle can consist of an eccentric magnet arranged eccentrically to the screw spindle axis, the magnetic core of which is articulated to a lever which is itself non-rotatably connected to a screw spindle shaft.

The back and forth movement of the adjustable mouthpiece is effected in that the lever connected to the magnetic core or to the screw spindle shaft is double-armed and that a tension spring is connected to the second lever arm and is suspended on the base frame of the printhead.

A favorable use of space of the available space in the needle printhead can also be achieved if the lifting magnet is arranged approximately parallel to the longitudinal axis of the printhead base frame in the area of the mouthpiece.

The movement of the mouthpiece is also facilitated in that the organ to which the mouthpiece is attached consists of a resilient strip.

Finally, an adjustment of the adjustment path for the mouthpiece can be achieved in that the screw spindle is provided with a screwdriver slot at one free end.

Embodiments of the invention are shown in the drawing and are described in more detail below.

• Fig. 1 eine Matrix für Schnellschrift mit einer 9-Nadeln-Spalte als 9 x 7-Matrix,
• Fig. 2 eine Matrix für Schönschrift mit derselben 9-Nadeln-Spalte, die pro Druckpaß verstellbar ist und erfindungsgemäß auf eine 18 x 28-Matrix erweitert ist,
• Fig. 3 ein erstes Ausführungsbeispiel für den erfindungsgemäßen Druckkopf mit verstellbarer Nadelspalte,
• Fig. 3a den Nadeldruckkopf gemäß Fig. 3 ohne das Gehäuse im vorderen Bereich,
• Fig. 3b den vorderen Bereich des Nadeldruckkopfes gemäß Fig. 3, ohne Gehäuse gezeichnet,
• Fig. 4 die beiden verstellbaren Mundstücke für ein 2-Nadelspalten-Mundstück in Grundstellung,
• Fig. 4a eine Matrix für Schnellschrift mit einer 9-Nadeln-Spalte als 18 x 7-Matrix,
• Fig. 5 die beiden verstellbaren Mundstücke gemäß Fig. 4 in einer die Spalte verfeinernden Matrix,
• Fig. 5a die Matrix für Schönschrift mit verstellter zwei 9-Nadeln-Spalten und verfeinerter Matrix in Schriftzeichenbreite als 18 x 28-Matrix,
• Fig. 6 die beiden verstellbaren Mundstücke gemäß Fig. 4 mit verfeinerter Matrix in Schriftzeichenbreite als 36 x 32-Matrix,
• Fig. 6a die in Stellung gemäß Fig. 6 entstehende 36 x 32-Matrix,
• Fig. 7 ein zweites Ausführungsbeispiel für den erfindungsgemäßen Druckkopf mit zwei verstellbaren Nadelspalten,
• Fig. 7a das Antriebssystem für die Nadelspalten-Verstellung gemäß Fig. 7, getrennt gezeichnet,
• Fig. 8 ein drittes Ausführungsbeispiel für den erfindungsgemäßen Druckkopf mit zwei verstellbaren Nadelspalten ohne Gehäuse des vorderen Bereichs gezeichnet,
• Fig. 9 ein viertes Ausführungsbeispiel für den erfindungsgemäßen Druckkopf, und
• Fig. 9a das Antriebssystem für die Nadelspalten-Verstellung gemäß Fig. 9, getrennt gezeichnet.

Show it

• 1 is a matrix for quick writing with a 9-needle column as a 9 x 7 matrix,
• 2 is a matrix for fine writing with the same 9-needle column, which is adjustable per print pass and is expanded according to the invention to an 18 x 28 matrix,
• 3 shows a first exemplary embodiment of the printhead according to the invention with an adjustable needle gap,
• 3a the needle print head according to FIG. 3 without the housing in the front area,
• 3b shows the front area of the needle print head according to FIG. 3, drawn without the housing,
• 4 shows the two adjustable mouthpieces for a 2-needle column mouthpiece in the basic position,
• 4a is a matrix for quick writing with a 9-needle column as an 18 x 7 matrix,
• 5 shows the two adjustable mouthpieces according to FIG. 4 in a matrix refining the column,
• 5a the matrix for fine writing with adjusted two 9-needle columns and refined matrix in character width as an 18 x 28 matrix,
• 6 shows the two adjustable mouthpieces according to FIG. 4 with a refined matrix in character width as a 36 x 32 matrix,
• 6a shows the 36 x 32 matrix which arises in the position according to FIG. 6,
• 7 shows a second exemplary embodiment of the print head according to the invention with two adjustable needle gaps,
• 7a shows the drive system for the needle gap adjustment according to FIG. 7, drawn separately,
• 8 shows a third exemplary embodiment of the printhead according to the invention with two adjustable needle gaps without a housing of the front area,
• Fig. 9 shows a fourth embodiment for the print head according to the invention, and
• Fig. 9a, the drive system for the needle gap adjustment according to FIG. 9, drawn separately.

According to a first embodiment, the matrix printer according to the invention has only one printing needle column 1 hen, which consists of nine printing needles 2 according to FIG. 1. With normal division of the matrix within the character width 3. or. of the character height 3a, ie a division into seven parts (matrix 9 x 7), the matrix printer writes fast writing. The mouthpiece 6 with the printing needle column '1 is in its zero position in the case of fast writing, in each case in reciprocating printing passes (printing directions).

According to FIG. 2, the matrix printer works in an incoming print pass, as described for FIG. 1. In the returning print pass, the mouthpiece is adjusted by an amount "x" and the adjustment involves an electronic change in the matrix division within the character width 3, which roughly corresponds to a doubling of the pressure points within the character "V" chosen as an example.

When switching from quick writing to fine writing, the matrix refinement in the direction of character width 3 can be selected in the sense of the invention and can e.g. as shown starting from a matrix 9 x 7 on 18 x 28 or on 18 x 40 or on 36 x 40.

The outline of the wire print head used for this purpose is shown in FIG. 3. As is known, the magnetic drives for the individual printing needles 2 are located on the print head base frame 4, which are guided within a housing channel 5 and essentially terminate with the mouthpiece 6. The individual printing needles 2 can be recognized as a point. Each pressure needle 2 is associated with an electromagnet, which is not visible further, all current leads 7 being combined in a common plug 8. The adjustment drive 10 for the mouthpiece 6 is assigned to the needle print head according to the invention in the front area 9, which is enclosed with the housing 11 in FIG. Instead of the housing 11 is a pluggable in Fig. 3a Ribbon guide shown.

The adjustment drive 10 is shown in FIG. 3b without the print head base frame 4 and without the housing 11. The mouthpiece 6 (without the pressure needles 2 drawn in the rear area) is held by an organ 12 which transmits the adjustment drive force, this consisting of the lever 13. The lever 13 forms pole faces 13a, 13b, which lie opposite the magnetic poles 14a, 14b of the electromagnet 14. The lever 13 is made of resilient material and is pivotally mounted about the axis 15. The poles 14a, 14b are held by the cross member 16. When a voltage is applied between the magnetic connections 17a, 17b, the magnet 14 pulls the lever 13 into a position in which the pole faces 13a, 13b bear against the magnetic poles 14a, 14b. The mouthpiece 6 assumes a corresponding position, wherein the adjusting screw 18 can serve either as an adjusting means with respect to the cross member 16 or as a stop in the pivoted-off position of the lever 13. The magnetic poles 14a, 14b can also consist of permanent magnets, the magnetic field of which can be completely or partially canceled by means of the electromagnet 14.

4 shows a two-part mouthpiece 6 consisting of the mouthpiece parts 6a and 6b as an alternative solution. The two mouthpiece parts 6a, 6b are held together by a parallelogram linkage 19 with the joints 19a, 19b, 19c and 19d. The pivot axis lies between the mouthpiece parts 6a, 6b. The needle gaps 1 are each formed from nine printing needles 2. The parallelogram linkage 19 is driven by a shaft 20 which is rotatably mounted on the printhead housing 4 in relation to the shaft 20 which is to be described in more detail in FIGS. 7a and 9a.

One when adjusting the parallelogram linkage 19 the slight arc movement occurring by the amount "x" (distance between two printing needles 2 within a needle gap 1) is negligibly small.

The normal position of the mouthpiece parts 6a, 6b shown in FIG. 4a serves for quick writing, which can be written practically twice as fast according to the two existing needle gaps 1 as with the single-column mouthpiece 6 according to FIG. 1. For this reason, the pressure points in the in Fig. 4a drawn 18 x 7 matrix drawn black filled.

An adjustment of the mouthpiece parts 6a and 6b according to FIG. 5 by the amount x / 2 (exaggerated in FIG. 5) is carried out by rotating the shaft 20 which engages the parallelogram linkage 19. The rotation takes place after each print pass and approximately in the time in which the advance of the recording medium, i.e. the paper web.

The fine writing shown in FIG. 5a is therefore based on an 18 × 28 matrix.

6 is adjusted by an additional amount of x / 4 compared to x / 2, which results in a 28 x 36 matrix. The result is a beautifully written and relatively quickly written font with no great effort in precision engineering and electronics with a single needle print head.

The needle print head with two adjustable mouthpiece parts 6a and 6b can be designed in several configurations of the adjustment drive 10.

7 shows the needle printhead according to the invention again with the printhead base frame 4, the housing cooling fins 4a has, with built-in magnetic drives, each for the printing needles 2 with the housing channel 5, in which the printing needles 2 are guided as usual, with the power supply lines 7 for the magnetic drives and with the collecting plug 8 and with the adjusting drive 10 arranged in the front area 9, which is surrounded by the housing 11. In order to also dissipate the heat, cooling air slots 11a are provided in the housing 11.

7a shows the adjustment drive 10 without the housing 11. The mouthpieces 6a, 6b are adjusted by means of the parallelogram linkage 19 and the shaft 20 mentioned. The intermediate member 21 is attached to the shaft 20 in a rotationally fixed manner. It has pole faces 22a and 22b which interact with flattened cores of the magnetic poles 23a and 24a of the magnets 23 and 24 fastened to the print head base frame 4. Here, the intermediate member 21 is in the form of a rocker 21a.

In the embodiment of FIG. 8, the needle print head is shown with the print head base frame 4 and without the housing 11 in the front area 9. The two magnets 23 and 24 are arranged vertically with their magnetic core axis. The magnetic poles 23a and 24a lie opposite the pole faces 22a and 22b of the intermediate member 21, which is also designed as a rocker 21a. The movement path of the rocker 21a is set and limited by adjusting screws 25a and 25b arranged in the pole faces 22a and 22b. A protrusion 26 is fastened to the rocker 21a, which is fastened by means of a pair of tension members 27, 28 to the parallelogram linkage 19, which cannot be seen any further and is located in the space behind the magnets 23 and 24.

The embodiment according to FIG. 9 is in principle what the print head base frame 4, the housing cooling fins 4a, the housing channel 5, the mouthpiece parts 6a, 6b and the housing se 11, which relates to cooling air slots 11a, the same design as the embodiments of the invention described above. Compared to the exemplary embodiment according to FIG. 7a, however, the flattened areas of the cores of the magnetic poles 23a and 23b are placed in vertical planes (FIG. 9a), and on the shaft 20 the intermediate member 21 is fastened in a rotationally fixed manner and in the form of a pointer 21b. The pointer 21b swings back and forth in the direction of the arrow 29 depending on the desired position of the mouthpiece parts 6a, 6b after the end of a pressure pass.

All of the needle print heads shown in FIGS. 3, 4, 7, 8 and 9 have fastening openings 30 and 31, respectively, through which screws are guided to the print head carriage, not shown, which is moved back and forth in front of the web-shaped recording medium in the print-fitting directions.

Claims (16)

1.Matrix printer with a needle print head that can be moved in print passes, which is in the printing position relative to a record carrier that can be moved between print passes, with an adjustable mouthpiece in which the needles are guided in columns in bores, the basic position of the mouthpiece for quick writing and other positions possibly in - And forth printing passports are provided for fine writing, characterized in that with the adjustment of the mouthpiece (6; 6a, 6b) in layers between two consecutive printing needles (2) in a needle gap (1), ie With a mechanical, finer division of the matrix into character heights (3a), at the same time an electronic, finer division of the matrix into character widths (3) is connected, whereby the ratio of the division into character height and character width for quick writing and for fine writing is at least 0.4: 1 is or greater. 2. Matrix printer according to claim 1, characterized in that in an at least two-part mouthpiece (6a, 6b) with two needle gaps (1) the refinement of the matrix from 9 x 7 to 18 x 28, 18 x 40 or 36 x 40 is made. 3. Needle print head for a matrix printer according to claims 1 and 2, characterized in that the adjustable mouthpiece (6) is connected to an organ (12) transmitting the adjustment drive force and that this member (12) is assigned to the adjustment drive (10) directly or with the inclusion of an intermediate member (21). 4. needle printhead according to claim 3, characterized in that the adjusting drive force transmitting member (12), optionally the intermediate member (21) and the or the adjusting drives (10) in the front region (9) of the printhead and arranged by a housing (11 ) are enclosed. 5. Needle printhead according to claims 3 and 4, characterized in that the adjusting drive force transmitting member (12) from a on the printhead base frame (4) mounted, pivotable lever (13) with pole faces (13a, 13b), which the poles (14a , 14b) of a magnet (14) that can be switched on and off. 6. Needle printhead according to claims 3 and 4, characterized in that the adjusting drive force-transmitting member (12) consists of a rotatably mounted on the printhead base frame (4) shaft (20) which carries the intermediate piece (21), the mutually facing pole faces (22a, 22b) is arranged opposite the magnetic poles (23a, 24a) of two magnets (23, 24) assigned to one another, the shaft (20) being connected to two mouthpieces (6a, 6b) by means of a parallelogram linkage (19). 7. Needle print head according to claims 3 to 6, characterized in that the adjusting drive (10) consists of one or two electromagnets (14 or 23, 24). 8. needle printhead according to claims 3 to 6, characterized in that the intermediate member (21) in the form of a rocker (21a) is formed (Fig. 7a and 8). 9. Needle print head according to claims 3 to 6, characterized in that the intermediate member (21) is designed in the form of a pointer (21b) (Fig. 9a). 10. Needle printhead according to claims 3 and 4, characterized in that the organ (12) connected to the mouthpiece (6) extends approximately in the direction of the needle bundle and by means of the adjustment drive (10) transversely to the direction of flight of the printing needles (2) A fraction or a multiple of a needle distance measured in the direction of movement can be moved back and forth. 11. Needle printhead according to claim 10, characterized in that the adjustment drive (10) for the back and forth movement of the organ (12) by means of a drivable in both directions of rotation, transverse to the direction of flight of the printing needles (2) extending, axially fixed screw spindle is formed. 12. Needle printhead according to claims 10 and 11, characterized in that the rotary drive for the screw spindle consists of an eccentrically arranged to the screw axis solenoid, the magnetic core is articulated to a lever which is itself rotatably connected to a screw shaft. 13. Needle printhead according to claims 10 to 12, characterized in that the lever connected to the magnetic core or to the screw shaft is double-armed and that a tension spring is connected to the second lever arm, which is hooked onto the base frame (4) of the printhead. 14. Needle print head according to claims 10 to 13, characterized in that the lifting magnet approximately parallel to the longitudinal axis of the print head base frame (4) in the region of the mouth piece (6) is arranged. 15. Needle printhead according to claims 10 to 14, characterized in that the organ (12) to which the mouthpiece (6) is attached consists of a resilient strip. 16. Needle printhead according to claims 10 to 15, characterized in that the screw spindle is provided at a free end with a screwdriver slot.

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