DE2422956A1 - PRINTER - Google Patents

Description

Applicant's file number: RA9-73-OO2

printer

The present invention relates to a serial
Printer with a movable printing unit and one or more stationary recording media.

A large number of serial printers have already become known which, in the case of stationary recording media, have movable ones Print heads, drums, disks, chains, etc. work. Apparently everyone belongs

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these printers are of the linear type, in which either the Printhead or the printing type sets distributed along a linear path corresponding to the maximum length of a print line are or can be moved along it. It was therefore necessary to either place one for each character along the line . Provide a print head or a device for linear transport of the print head or the hammer, which the recording medium hits against a print mark. In the prior art printers, this necessity has created difficulties since the construction of a precise linear drive device for a movable print head the use of a mechanically complex and expensive lead screw or an equivalent drive system with tension belts or rack conditional to move a carriage supporting the print head or hammer back and forth. In particular, the quick print has with chain printers and disk printers at very high speeds out of the devices carrying the printing types or the print head. This in turn made it necessary, very complicated and use accurate clocks and positioning facilities. the exact alignment between the rapidly circulating print type set and the respective printing position.

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In addition, a linear printer takes up a relatively large amount of horizontal space Space, generally much more than the maximum width of a horizontal print line. The expert is known that the mechanical effort in linear printers is extremely large, which leads to susceptibility to failure in particular of the lead screw or the pull cable. the The use of a print hammer or type set for each individual or a few character positions is extraordinary expensive and requires very precise timing and coordination between the moving parts of such a system Printer.

To avoid the aforementioned disadvantages of the already known Printer, the object of the present invention is to provide an improved, more compact serial printer, whose construction is simpler and at the same time more reliable.

According to the invention, this object is achieved in that the printer is characterized by at least one printing unit a support for receiving and setting the printing unit in the printing position with respect to at least one recording medium; by a rotatably mounted shaft which is arranged at a fixed radial distance from the recording medium perpendicular to the radius is, wherein the support is rigidly connected to the shaft, such that the printing unit carried by it upon rotation the shaft describes an arc of a circle; by at least one arch-shaped pressure abutment, over which the recording

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carrier is led; by drive means that can be coupled to the shaft, and return means connected to it for producing a reciprocating movement during printing and reversing; and by a scanner for scanning the instantaneous position of the shaft and thus of the printing mechanism with respect to the recording carrier.

According to the invention, the printer can advantageously be used as a Wire printer be designed.

Advantageous further developments of the printer are characterized according to the invention in that the resetting means are designed as a spiral spring which is arranged between a fixed housing part and the shaft, such that it is in applied a torsional force on the shaft or that a counterweight is arranged on the shaft in such a way that that the center of gravity of the arrangement consisting of the printing unit, counterweight and shaft lies on the axis of the shaft or that several pressure plinths with a recording medium carried over them are provided or that the scanner has at least one light source and at least one light-sensitive light source aligned therewith Has cell, and that the light impinging on the cell by a arranged on the shaft and with Openings and breakouts provided is interrupted when the shaft rotates.

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An embodiment of the invention is shown in the drawings and is described in more detail below.

Show it:

Fig. 1 is a perspective view of the partially cut open Printer;

Figure 2 is a cross-section through the scanner of the printer.

In Fig. 1 are the most important elements of a preferred embodiment of the printer according to the invention. One Shaft 1, the main shaft of the printer, is arranged in a vertical position. The shaft 1 is driven by a gear 2 driven, which in turn meshes with a gear 3 which is arranged on the shaft of a reduction gear, which is driven by a drive motor 4. The motor 4 runs continuously. The power of the engine is above that Gears 2 and 3 are available with an angular speed adapted to the printing process. The gear 2 runs freely of shaft 1 if it does not transmit power to shaft 1 via a coupling 5. The clutch 5 is not in

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Detail shown in the figures. A preferred embodiment the clutch 5 is in the IBM Technical Disclosure Bulletin, Vol. 14, No. 2, July 1971, pages 455 and 45G. The relatively slow rotation of the gear 2 is transmitted to the shaft 1 through the clutch 5, by tightening the end of a coil spring within clutch 5, as is the case with many known spring clutches. The tightening the spring can be done by an electromagnet, not shown, when the rotation of the shaft 1 is desired for printing. With wave 1 the elements fixedly arranged on it rotate at the angular speed of the gearwheel 2.

A support 6, which carries a print head 7 and a counterweight 8, is fastened to the head of the vertically arranged shaft 1. The print head 7 can preferably be designed as a matrix wire printer, as described in US patents 3, 108'534, 3'592'311 and 3'G72'482. The print head 7 can be firmly connected to the support 6 by means of screws 9, for example. A nose 10 of the print head 7 is arranged near one or more abutments 11, several of which are shown along the circumference of a housing 12 and in horizontal alignment with the nose 10 of the print head. The arcuate abutments 11 are fixed in the housing 12. You can be longer or shorter, as shown in FIG. 1, and more or less numerous.

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It is not necessary to use a specific type of matrix wire printer, since the known serial dot matrix wire printers and serial whole-character wire printers are equally suitable. Us can also use electric discharge printers with electrically sensitive paper
can be used, as well as hot-wire matrix printers with heat-sensitive paper.

In Fig. 1 three Di ¹ Uckstations A, B and C are shown with which
multiple copies of the same data can be made. That is
For example, desirable in retail, where Averden is to be printed on cash register coupons for the customer, warehouse slip or a journal strip that remains in the machine, as well as on credit cards or checks. A paper tape 13 is shown at station B, which can be wound onto a receiving roll 14 by means of a device (not shown) after it has been guided past the abutment 31 from a supply roll (not shown). The transport of the paper tape 13 can take place by driving the take-up roller 14 by means of a shaft 15 or by friction wheels 16, which are shown at the printing stations A and C. The friction wheels 16 press against a surface of the paper tape 13 and
transport this up or down if they are by suitable
Means such as a stepper motor or a continuous one
running engine can be driven with a clutch.

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In the preferred embodiment of the invention, there are Hardened steel abutment 11. However, it is clear that when using Another type of printhead, such as an EDM printer, a suitable abutment is to be provided. An arrow 17 on the counterweight 8 indicates the direction of rotation of the print head when the clutch 5 is actuated. In this example the Counter-clockwise rotation of the counterweight and printhead, which are connected to the support 6. The counterweight 8 compensates Mass of the overhanging support .6 as well as the print head attached to it, so that the entirety of the attached to the end of the shaft 1 Elements is dynamically balanced against unwanted vibration or movement as a result of external influences.

When the clutch 5 is switched on, the print head 7 rotates at a constant rate Speed. In the case of a matrix wire printer, it is known that printing is carried out by advancing one or more of one or more of them A multitude of fine wires either against a pressure-sensitive recording medium or against an ink ribbon and then against the recording medium. Another possibility consists in arranging an abutment 11 carrying ink on the one facing away from the print head Side of the recording medium so that printing takes place from the reverse side. In the preferred embodiment of the invention is a with Ink-soaked ribbon accommodated in a cassette (not shown) arranged on the counterweight 8. The cassette is designed so

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back head v

that the ribbon out of it to the ISiase 10 of the printhead around and back into the cassette, with suitable drive means being provided. One such cassette is in US patent 3'7-8'012 described.

As it rotates, the print head 7 sweeps over an arcuate path along which the various printing stations A, B and C are arranged. If necessary, it can also have a continuous printing station a continuous abutment can be provided. It will be understood that a suitable electronic control circuit must be provided that the activation of the individual print wires and the setting of the print head controls to a specific print position.

Such a control device is shown in FIGS. It consists of a scanner 18 for the angular position, the shaft 1, which scanner contains a light source 27 and a photodetector 28, which are arranged on opposite sides of a breaker equipped with openings 20 and 21 on its periphery. Such optical position scanners are known. Their mode of operation is based on the fact that light is thrown onto one side of the interrupter 19 falls through the openings 20 and 21 when they move between the light source and your photodetector. With every round an opening between the light source and the photodetector becomes a

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electrical impulse generated. These pulses can be counted as a characteristic of quantized movement by suitable counters in order to allow the relative position of the print head along the print path to be determined with any degree of accuracy in relative numbers of steps which correspond to the arrangement of the openings on the interrupter 19. Instead of the scanning device described, means for scanning optical or magnetic markings, mechanical brushes or the like can also be provided. It is known, however, that either the source and the scanning element must be moved with respect to the fixed interrupter, or vice versa, since it is the relative movement between these elements that is scanned. In a preferred embodiment of the invention, a perforated interrupter 19 is used which has a plurality of closely spaced openings 20, the scanning of which supplies pulses which correspond to the character widths covered by the print head. Openings 21 of slightly larger dimensions and far apart are used to derive block information, such as the indication that the print head is at the beginning of a line on station A, station B or station C. These block signals correspond to the grooves 21 and the large cutout 22 on the periphery of the interrupter 19.

Means must also be provided for the printhead with its Support 6 can be returned to its original position by reversing the direction of rotation of shaft 1 when printing at the last station,

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to v / which printing is desired \ var, is finished. Im preferred Embodiment of the invention this is achieved by the arrangement of a spiral spring 23, which stores energy when the shaft 1 through the clutch 5 is connected to the gear 2 to move the printhead along its printing path in the counterclockwise direction. .If the clutch 5 is switched off at the end of the printing process, the energy stored in the spring 23 is released to return the print head 7 and the counterweight 8 clockwise to their original position. Any recoil forces that occur can be avoided by the arrangement of a Shock absorber 24 are caught against which the support 6 starts when it has reached its starting position.

By means of ball bearings 25, which are provided at both ends of the shaft 1, ensures that the balanced system described is free can turn.

Figure 2 is a more detailed representation of the position sensor 18, of the breaker 19 and the openings 20 and 21. As already mentioned, the interrupter 19 is attached to one end of the shaft 1, while "the matrix print head 7 with its support 6 at the opposite end the AVeil 1 is arranged non-rotatably. The shaft 1 was. To attach of the interrupter 19 is chosen because its rotational movement is relatively slow and because the print head 7 with the other end of the A-line is firmly connected, so that pressure position deviations due to play

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in the drive and changes of the 'MiHnrdreliXahl which would otherwise lead to errors in the exact determination of the position de ;; Dj-uckkopies with regard to the position of the interrupter 19 would result. The "breaker 19" has openings which can be referred to as lattice-shaped. In the preferred embodiment, this gate is made of etched aluminum, although it could also be made of plastic, photographic film or any other opaque material Similarly, reflective material, as used in optical character recognition, or magnetic material, as used in Mauritian character recognition, can be used. when the printhead 7 serves the three separate printing stations. The actual linear speed at the cheese 10 of the printhead 7 is about 22 cm per second than the radius of the Xase 10.

The grid of the interrupter 19 consists of three groups of 30 slots each each with a width of 0.5 mm. These slots are indicated by 20 in the figures and each slot corresponds to a time stamp for the beginning of one Character print cycle. These slots are spaced apart from one another of 1 mm, and they are eggs with a radius of 7.5 cm from the center Shaft 1 arranged. The actual character spacing on the printhead

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occurs, is 2 mm because of the grosseron radjus on the nose

C-

Printheads. This radius can be about 15 cm.

A second series of grooves or slots 21 and an outbreak 22 on the interrupter 19 determine the basic position of the pressure head and the beginning of the line for each of the three printing stations Λ, B and C. This Part of the grid is arranged on the outer periphery of the interrupter 19 and is thus still radially outside the grid of openings 20. The electrical system used in this exemplary embodiment requires that the starting position differs from the three line endings. The grooves 21 and the cutout 22 are arranged so that two photodetectors 28, one for the grid of openings 20 and one for the grooves 21 and the cutout 22, can only be activated in the starting position, so that these of the three line endings, which are through the grooves 21 are defined, is differentiated. Accordingly, 19 pulses are generated depending on the movement of the interrupter, each character position correspond, a separate pulse is generated by the grooves 21, and finally a double pulse is generated by precise positioning a groove 21 and one of the openings 20, so that bei.de detectors simultaneously are activated when the print head 7 is shown in FIG Starting position is.

The scanner 18 is a commercially available dual light device emitting diodes 24, which are arranged with a mutual distance of 0, 5 mm on one side of a U-shaped block and on the g

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lying legs of the U are aligned. On this opposite one Legs of the U are provided with lenses 2G, which the Light emitting emitted light on photodiodon or PhoLo cells 28 focus kidneys, which always generate an electrical impulse, if light from one of the light emitting diodes through an opening or a. Xut of the breaker 19 falls through. In the case of the above-mentioned erasers, and opening dimensions, the scanner 10 delivers a timing pulse to the electrical control circuit for 47 arc minutes and 45 arc seconds each ;. that the printhead has traveled. This arc corresponds approximately to one pulse per 9.4 milliseconds in the case of the preferred embodiment used speed of rotation of the shaft 1.. These pulses are via a line to the control circuit, which is then fed at intervals of 0.9 millisecond signals for the actuation of the pressure wires generated. Of course, this assumes that a character is to be printed at all.

Although not shown in detail in the figures, it is obvious to a person skilled in the art that the signals for the generation of PUiiktr-irUrix characters must be generated by a control circuit at the correct time and in the correct order so that the characters are printed as desired can be. Such circuits are known and do not constitute Toil of the present invention, which exclusively concerns the Druekmeehar can derive electrical impulses for actuation of the print wires in the print head. In principle, two operating modes are possible with wire printers:

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If required, a · / .el η can be printed or \ va: -; usually the case and is generally more economical, one ■ Yielzf.hl of character, generally stored in accordance with a line length, wcrd'Miin a <tn buffer and when fully dei · saliva ¹ and the print head is in its initial position, starts, the electronic control circuit with the reading of the contents of the memory, and simultaneously therewith, the print head is displaced in notation by turning on the clutch · ^Γ 3, so that the generation of each character position lmpulses by the scanner 3, the above for cIhk forms of the desired Character-specific print wire actuation must be generated and fed to the corresponding driver circuits of the print head in order to print the characters on your recording medium.

In the preferred embodiment of the invention, the LUick-Jjchr of the printhead in its starting position the activation of two photocells, their combined and simultaneous signal, as mentioned, used by the control circuit to indicate that the printhead returned to its original position and ready to print a new one Rows of data is ready. The data representing the characters to be printed are then transmitted in serial dot form for each character while the printhead is moving, with the scanner 18 starting a Character print position, as described, detects. In the illustrated

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In a special embodiment, the same data are printed at one, two or three printing stations, with the printing normally being carried out at stations A and B each time, but at station C only if a document is to be printed by hand in the printing station has been introduced. By inserting a document by hand into the printing station C, a microscope holder (not shown) is closed, whereby the control circuit is informed that a recording medium is present and the print head has to traverse the full length of its print path in order to Print station C. If no recording medium has been introduced into the station C, the coupling 5 drops out when the second line end signal is scanned by the scanner, so that the return spring 23 can return the print head to its starting position. '

The aforementioned configuration of the preferred embodiment of Invention has a number of advantages. First, the need to support the main shaft 1, the shaft on which the gear 3 is mounted, and • The ball bearings used in the reduction gear cannot be precision ball bearings as they are not exposed to any particular loads. In particular Due to the continuously running motor, there are no large loads and stresses on the motor shaft or in the gearbox, because the matrix print head 7 has a relatively low mass and is balanced by the counterweight 8, so that in addition to the low torque when storing

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of energy in the spring 2Π nu <- you? Tiotational inertia of the system must be overcome. The output speed of gears 2 and 3 on the shaft 1 via the coupling 5, assuming that the Print head could complete one full turn of 3CO, only 13 turns per minute, so that the bearings 25 that carry the shaft 1 do not have to be designed for high speed or heavy loads.

Because of the low speed at which the shaft 1 is driven, the motor 4 does not have to have a high torque in order to accelerate the pressure mechanism and to store energy in the spring 23.

The power required for a complete sweeping of the printing positions from the initial position to the end of the line of the last printing station and back again corresponds to that of the order of magnitude a linear printer, but the stress is much lower because of the slow speed and because of the simple construction the return device. The printer described is of course essential more compact than a corresponding linear printer with three adjacent ones Printing stations, as the linear transport mechanism as well as the lateral ones Guides and bearings are absent. Since the paper takes the form of the arcuate abutment in the printing stations, it has one particular rigidity in its transport direction. This makes it possible to use a significantly simplified feed mechanism for the paper guide to use.

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The print head 7 and the interruption 19 are, as mentioned, attached to the ends of a rigid shaft. Dadux'ch results in an extremely accurate sensing of the position of the print head, which is not suffers from play or manufacturing tolerances. The exact setting of the print head in relation to the interrupter can be done in a simple manner take place by means of an adjustment screw.

Because of the continuously running engine, which has a clutch with can be connected to the drive of the print head, the inventive Printer does not have a stepper motor or a stepper device.

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Claims (6)

PATENT CLAIMS Printer marked with at least one printing unit / by a support (6) for receiving and setting the printing unit (7) in the printing position opposite at least a recording medium (13); by a rotatably mounted shaft (1) which is at a fixed radial distance from the recording medium (13) is arranged perpendicular to the radius, the support (6) being rigid with the shaft (1) is connected in such a way that the printing unit (7) carried by it forms an arc of a circle when the shaft (1) rotates describes; by at least one arcuate pressure abutment (11) over which the recording medium (13) is led; by drive means (2, 3, 4, 5) which can be coupled to the shaft (1) and which are connected to it Return means (23) for producing a reciprocating motion during printing and reversing; and by a scanner (18) for scanning the instantaneous position of the shaft (1) and thus the printing unit (7) with respect to the recording medium (13). 2. Arrangement according to claim 1, characterized in that the printing unit (7) is designed as a wire printer. RA9-73-OO2 -18- 409883 / U 819 3. Arrangement according to claim 1, characterized in that the restoring means (23) designed as a spiral spring are, which is arranged between a fixed housing part (12) and the shaft (1), such that they are in pulled up condition exerts a torsional force on the shaft (1). 4. Arrangement according to claim 1, characterized in that on the shaft (1) a counterweight (8) in such a way is arranged that the focus of the printing unit (7), counterweight (8) and shaft (1) Arrangement is on the axis of the shaft (1). 5. Arrangement according to claim 1, characterized in that several pressure abutments (11) with overridden Recording media (13) are provided. 6. Arrangement according to claim 1, characterized in that the scanner (18) has at least one light source (27) and at least one light-sensitive cell (28) aligned therewith, and that the light impinging on the cell (28) through a light arranged on the shaft (1) and having openings (20) and Breakouts (21, 22) provided breaker (19) is interrupted when the shaft (1) rotates. RA9-73-OO2 -19- 409883/0819