FR2841178A1 - Industrial multi-head printing device has position encoders around rotation axle of pulley of driving belt and digital controller controls operation of belt - Google Patents

Abstract

A structure includes a set of printing devices (2), displacement and position detectors (41). A drive belt (3) drives at least one printing device (2). One or several printing devices may move along of pulled by the belt. One or several position encoders (7) are included around rotation axle of a pulley of the driving belt. A power supply feeds the drive. A digital controller controls operation of the belt.

Description

the predetermined position.

28411 78

The state of art.

  The present invention relates to a device for the rapid movement of printing holidays for labels. The device

  according to the description comprises means of displacement, encoding of

  precision and control of speed and position.

  In the food industry in particular, the packaging of fresh products must contain different indications which inform the consumer of information concerning the place of manufacture, the expiry date, etc. In addition, to facilitate the monitoring of these products, wind bar codes often included. The printing of these indications previously mentioned, must be done in real time on the production line of the product in synchronism with the production rate and consequently, undergoes the same constraints imposed on it, namely: speed of printing -session, the accuracy of the location of

[print, etc.

  At the moment, there are three great printing techniques for identified labels: inkjet, laser and heat transfer. The first technique uses a piezoelectric or thermal type ink jet head which projects micro droplets (or bubbles) of ink onto the support thus forming the pattern; the second of the laser beams focusing on the surface of the material to mark and printing is by superficial burn of the surface at the impact; the third technique, scrolls an inking film in front of a printhead and through a thermal process, transfers dry ink from the inking film to the label. In all cases, the print head must make long movements and one or more wind labels printed during this trip. In general, the labels are distributed over the width of the web to be printed and the spacing of label lines is defined according to the size of the packages to be produced.

  can vary from a few centimeters to several tens of centimeters.

28411 78

  When printing the labels, the print head must move from one side of the web to the other; stop on the areas to be printed; accelerate during the vice zone and repeat this sequence as many times as necessary in a minimum of time. The printhead is mounted on a trolley with translational movement, motorized by an electric motor that allows movement while the positioning of the printhead is obtained with the addition of an encoder mounted either on the exe the motor is on the drive shaft of the truck. The advantage of such devices with electric motor drive is the ease of design and simplicity of assembly. Two methods of entramement associated with known electric powertrains: notched belt drive and worm drive. The first pair has a sufficiently powerful and fast motor, allows strong accelerations, but is limited by the mass of the load to be displaced; indeed, the acceleration capacity of the system is inversely proportional to the inertia of the load. It should be remembered that the weight of a thermal transfer head weighs about ten kilograms, which requires a high starting torque during the transient phases of the movement; Repeated application of this torque to the belt tends to deteriorate it prematurely. The second known method corrects the major defects of the first, but at the cost of a reduced movement speed and acceleration practically nonexistent, which strongly penalizes in terms of performance. Given the speed of impression achieved by current events, be they inkjet or thermal transfer (> 1m / s), the overall bandwidth speed at printing is essentially governed by the movements of the Party. In the current state of the art, a print sequence covering a bandwidth is made in approximately 4 seconds (round trip) for a bandwidth of 70 cm, however the actual print time is about 0, 7 what accounts for more than 80% of

unproductive time.

28411 78

  As a result, there is a clear need for a new industrial printing system with fast moving speeds, high acceleration and braking capability, and a positioning accuracy. compatible with [use of [jet printing

  ink and thermal transfer whether intermittent or continuous.

Summary of the invention.

  In the general embodiment of the invention, the device is essentially composed of a pneumatic or hydraulic translator of the type "rodless cylinder with firm profile", a rotary encoder mounted on the pulley at the end of the jack, a printing device integral with the mobile part of said translator and a servo unit associated with servo-valves and controls managed by a control system

  numerical optionally computerized.

  In the first particular embodiment of the invention, a device derived from that described in the general embodiment, is equipped with a linear translator, a printing device which can be a thermal transfer, jet of ink or laser, end of stop

  and a detection cell associated with the butees.

  In the second particular embodiment of the invention, the apparatus based on the general principle previously described, has a linear translator equipped with a linear encoding system combined with another rotary coding system, allows the device to impression of moving with improved precision and smooth operation of the moving slide of said translator

done from the printing device.

  The third particular embodiment of the invention consists in using only an absolute angular position encoder mounted on an end axis of the linear translator and which provides the position of the printing device to the control system. The movement of

28411 78

  The printing device is then controlled according to its starting position and the one to be reached, the accelerations and wind breaks faster and the overall efficiency of the system is improved. This configuration makes it possible to use pneumatic or hydraulic translators in combination with continuous thermal transfer printing devices, which up to now have not been possible.

  than on electric cylinder systems.

  The term "printing device" refers to printing apparatuses comprising at least one print head and

  incidentally internal mechanisms or electronics.

  The term print head N includes the functional part of the

  printing device which ensures printing.

  The term intermittent printing N is applicable to a thermal transfer device, in which a movable printhead is

1 5 riding.

  The term continuous printing is applicable to a thermal transfer device, in which an ink film runs in front of a head.

fixed printing.

  The description of the embodiments of the device according to

  The invention is illustrated by figures appended hereto as follows: FIG. 1 is a general view of a set of label printing device integrated into a production line

according to the main description.

  Figure 2 is a view of the medium to be printed with the printing areas.

  Figure 3 shows an enlarged view of the printing areas.

  Figure 4 shows the details of an inkjet printing. Figure 5 shows the details of a thermal transfer printing. Figure 6 is the functional diagram of the printing apparatus

according to the invention.

i

28411 78

  FIG. 7 is a functional view of the apparatus with its frame

  guide and its means of displacement.

  FIG. 8 is the functional view of the corresponding apparatus

  has a particular embodiment.

  FIG. 9 is the functional view of the corresponding apparatus

  has another particular embodiment.

  FIG. 10 shows a functional diagram of the linear translator

has firm profile.

  FIG. 11 is a detailed view of the assembly of the angular encoder

10 on the axis of the translator.

  Detailed description of the invention.

  The invention is mainly adapted to lS systems for printing identification labels on packaging

  industrials. The apparatus according to the description of the invention is

  Particularly suitable for intensive use or a continuous flow of products to be labeled is to consider. FIG. 1 schematically shows a production line where the packages 11a and 11b wind are entrained on a conveyor 10, preferably horizontally, in the direction indicated by the arrow 10I. The arrangement of the packages 1a on the conveyor 1O is made so that their location is always known to the pressure control and closure system 12. A packaging film 9 runs from the reservoir gl, passing through the tensor 92 and following a movement 91O is in synchronism with the advancement of the conveyor 1O. It should be noted that a regular arrangement of the packaging lla on the said conveyor will have the effect of simplifying the management of the unwinding of the film 9. A printing device 2 is provided on the path of the film 9, thanks to the guide 6 and is endowed with an alternating linear motion perpendicular to the displacement of the film and parallel to the plane thereof. The printing is done during the stop of scrolling of the film 9. The device of impression 2 is able to traverse the entire width

28411 78

  of the film 9 for the purposes of printing. Simultaneously, during the stoppage of the flm, the device 12 optionally equipped with a thermal elevator and driven in a displacement 121, soda the flm 9 on

  the package 1 la and cut the said film in the same operation.

  The closed package 11b continues on the conveyor 10 for the following operations. It should be noted that the packaging can be stored online next to each other and line after line, so each line

  several packs wind imprinted and closed.

  FIG. 2 shows an example of label network 93 forming 10 horizontally and vertically label lines on film 9. The number of labels in a horizontal line is limited only by the label width and the number of labels. label to print. The stickers

  93 wind separated by at least one length of package 1 la.

  An enlarged view of the film 9, as shown in FIG. 3, makes it possible to see the details of the paths of the printing device 2 along a line of labels. In fact, the device 2 carries out a closed loop movement at each label line, the printing can then be carried out either on a single way as indicated in Figure 3 or in return; knowing that the round-trip mode is not applicable to all types of printing especially those using heat transfer for ink deposit. In single-mode operation, the device according to FIG. 3 carries out the path 931 to reach the zone to be printed 93, then a path 932 corresponds to the printing of the label; the 931/932 cycle is repeated as many times as there are labels to print on one line. At the end of the label line, the printing device 2 then performs a reverse path 933 to return to its initial position. It is obvious to one skilled in the art that in a round-trip printing mode, the same cycle 931/932 would be repeated in the

reverse.

  There are currently three printing techniques that can be used in the industry on automated production lines, which are: inkjet, heat transfer and laser. This being, [the impression

28411 78

  Laser is considered too demanding at the tolerance level on the print head / film distance which makes its diffusion limited. The ink jet is well adapted to fragile substrates or the absence of direct contact with the object to be printed is advantageously exploited. Finally, thermal transfer printing is widely used in packaging printing or direct contact with the surface to be printed is authorized, this technique is gable and efficient while its

  Cost of use remains competitive.

  The apparatus according to the present invention is particularly suitable for inkjet and thermal transfer devices. Figure 4 of the document shows the principle of an inkjet printing in which the pattern is printed by lines 270, each line is composed of a number of points which can be printed 271 or vices 272. The

  combination of several lines 270 forms a pattern or a character.

  In Figure 5 a similar description is given for printing

  A thermal transfer in which, lines 280 wind to achieve successively to form a pattern, each line is made with printed cells 281 and 282 vices cells. The distance separating each line of a pattern is of the order of a few 1/10 of a millimeter. In a general embodiment of the apparatus according to the

  description of Figure 6, the operating principle of the apparatus

  is described in the following manner: the printing device 2 is mounted on a linear translator 3 and thus has reciprocating movements along this translator. The translator 3 is controlled in translation by means of servovalves 31 which in turn are actuated by the numerical control 7 optionally connected to a computer for the control in real time. The translation of the device 2 is secured by race stops 4 which detect the presence of the sensitive cell 41 mounts on the printing device 2. The stop 41 thus inform the CN 7 of the homing and ending of the printing device 2. A rotary encoder 5 mounts on the axis of

28411 78

  rotation of the internal pulley of the translator 3, provides the exact position of the device 2 according to the angular position of the pulley CN 7 and in some cases to the printing device 2. Finally, the printing device 2 communicates with the NC 7 via API 8 (Programmable Logic Controllers). The schematic diagram according to Figure 6

  provides an overall description of a printing system that can

  support different types of printing technology such as inkjet or thermal transfer whether it is intermittent or continuous printing. As for the elements composing the system, the technologies used can be selected according to the needs of each use without any real impact on the operating principle of said system.

  In the schematic description of Figure 6, the translator

  Linear 3 can be pneumatically or hydraulically controlled without affecting the operation of the system. The sensitive cell 41 associated with the stop 4 may be replaced by a magnetic or optical rule associated with a magnetic cell or photo emitter / receiver. The servovalves 31 may in some cases be replaced by solenoid valves of the type l5 / 2] * or [3/2] * depending

  characteristics of the apparatus to be realized.

  In the first particular embodiment of the invention, described in FIG. 7, the apparatus is designed in such a way as to be able to receive intermittently printed inkjet or thermal transfer printing devices. The frame 6 is built in mechanical structure supporting the translator 3 in parallel with a guide bar 61, end stop 4 end wind position arranged at each end of said translator. Linear Translator 3 is selected from the families of rodless firm-stemmed products, which are like the family members of the Rexell family of Rodless Cylinder Kostalo, of the wind well suited for this purpose. This type of jack has a piston sliding inside a cylinder feeds pushed on both sides, the piston is attached to an external slide which is relic

28411 78

  has a closed entremment band on two 'crazy' pulleys. Such a principle of operation is comparable to that of the slides with electrical drive for example. However, the advantage of using a pneumatic or hydraulic device lies in the low inertia and good immunity to external aggression. In the embodiment of Figure 7, the printing device 2 is mounted on the slider of the translator 3 so that the print head 21 is oriented towards the surface of the medium to be printed. The device 2 is first brought up to one of the two stop positions and then to the other stop; once this initialization has been carried out, the programmed feeding of the two chambers of the translator's jack 3 makes it possible to reach any position between the two stops 4. This type of apparatus has the advantage of being simple and therefore very robust. In use, the pneumatic or hydraulic type of translator offers acceleration and braking performance well above the electric jacks conventionally used in this type of application. The usual acceleration values obtained with this type of equipment reach the OG, which represents up to 10 times those obtained with electrical devices. The printing device 2 described in this first embodiment is a thermal transfer printing

  intermittent as for example the model SmartDate_ 3i Markem.

  This type of printing device is characterized by a high weight (≥ 1 Okg) which tends to strongly penalize

low acceleration.

  Figure 8 shows the second embodiment of the invention in which the apparatus is constructed to be servo-controlled by the digital control system. FIG. 8 shows the apparatus only equipped with the linear translator 3, the printing device 2, the end-of-travel stops 4, the detector cell 41, a magnetic or optical precision rule 42 and an encoder rotary

Position 5.

28411 78

  Depending on the type of rotary encoder used, the apparatus according to the

  description of Figure 8 may be associated with either a device

  intermittent print thermal transfer with either continuous printing. For printing with an intermittent device such as SmartDate 3i, printing is done device 2; in fact, the label is printed by the internal displacement of the printhead (not shown) in a window called the print window (the size of the label is determined by this window). requires the use of the rule of precision 42 arranged along the translator, at each label the device 2 hangs on the area to be printed and the print head scans its window, then the print head rises and the The advantage over the first embodiment is better placement accuracy.

and a smooth operation.

  The continuous printing device like the Markem SmartDate 3c works in a different way and requires the use of an additional position encoder. Indeed, the print head (not shown) which is always inside the device 2 is fixed and the ink film is produced in front of this head during the writing operation, in fact, during the printing phase. writing, it is the displacement of the device which ensures the impression of the desired pattern, during this phase, the speed of the device 2 is synchronized with that of the ink film which passes in front of the print head so as not to tear off this film by friction with the medium to print. The quality of the printing and the reliability of the wind device are assured by the precision of displacement and positioning of said device. For this, the use of a precision rule 42 for detecting the position of the device 2 combined with the information provided by the incremental rotary optical encoder mounts on one of the axes of the internal pulleys of the translator 3, allows the device 2 to have the

required regularity.

l

28411 78

  The third embodiment of the invention according to the description

  of FIG. 9 shows a printing device 2 with continuous printing as explained above, goes up on the translator 3 as before. The device 2 is equipped with a detector cell 41 associated with the two ends of stop 4. An optical position encoder; a absolute coding is mounts integral with the axis of one of the pulleys crazy quotes to the translator 3. As the device 2 is itself integral with the slide of the translator and according to the operating principle described above, any movement of the device 2 is faithfully transmitted to "crazy" pulleys. The encoder 7 is of absolute type, thus the position of the printing device 2 is permanently recognized regardless of the state of the equipment, even after a reset of the control system. which avoids the phases of reinitialization. The assembly of the encoder 7 requires a modification of the support mechanism of one of the idler pulleys internal to the translator. In fact, the mechanical support part of the pulley is replaced by a new mechanical structure supporting both the pulley and the encoder 7. FIGS. 10 and 11 describe the differences between a standard linear translator of the stemless type << Kostelo_. (view a) and the same translator equipped with an encoder encoder absolute encoding position (view b). FIG. 10 schematically shows the translator 3 with its slider 35 endowed with linear reciprocating motion, the slider is secured to the drive belt 33 which forms a loop around the pulleys 31, a spring device (not shown) is provided with the band 33 to eliminate the training jouxes that may exist during the changes of direction of displacement. The view (b) differs from the view (a) by the addition of an encoder 7 mounts in the axis of the pulley 31 and integral therewith. In Figure 1 1, a

  basic description of the assembly of the encoder 7 and the pulley 31 is

  given. Wind bearings 34 added in the structure of the translator and wind mounted greenhouses in the housings made for this purpose (not shown), the exe 32 is assembled on the rotating rings of the bearing and

28411 78

  supports at its center the pulley 31, the pulley 31 is secured to the exe 32 by the use of a hexagonal head screw or key, the end of the exe 32 is mounted the rotating exe of the encoder 7 which is therefore also integral with the rotating assembly. This embodiment has the advantage of not modifying the operating principle of said translator. The embodiment corresponding to FIG. 9 makes it possible both to move the printing device 2 to the speed of writing by supplying said device with speed information necessary to advance the ink film and to accelerate this same device. during inactive phases. The time gain over a printed width is

  the order of 100% with a thermal transfer device.

  The embodiments described in this document all

  adaptable to most printing devices exist in the

  trade whatever their technology. The description of the modes of

  The invention relates particularly to thermal transfer devices because these correspond to the most demanding cases in term

  dynamic (weight). This particular description is not intended to limit

  The use of this type of device, on the contrary, covers the use of any other printing device, be it ink jet, laser, etc.

  The invention, according to its embodiments, makes it possible to increase

  significantly the performance of the printing equipment

conventional electric cylinder.

28411 78

  1) Apparatus for industrial printing capable of receiving one or more printing devices and characterized by: A housing receiving the printing, printing and printing components;

  displacement and position detection.

  A linear translator without a game supporting at least one printing device. One or more printing devices mounted on the part

mobile of said translator.

  One or more position encoders mounted in the axis of rotation

  of the drive pulley of said translator.

  IJn feeding system for the said translator.

  A numerical command managing the functions of the said translator.

  2) an apparatus for industrial printing according to claim 1 characterized by the fact that said translator is of the type without rod firm profile 3) -: An apparatus for industrial printing according to claim 1 characterized by the fact that said translator can

  be a pneumatic or hydraulic energy.

  4) An apparatus for printing according to claim 1 characterized by the use of one or more printing devices.

Thermal transfer.

  5) An apparatus for printing according to claim 1 characterized by the use of one or more inkjet printing devices. 6) An apparatus for printing according to claim 1 and

  characterized by the use of a laser pressure device.

  7) Apparatus for printing according to claims 1 and 4

  and characterized by the use of one or more continuous transfer thermal printing devices

28411 78

  8) Apparatus for printing according to claim 1 and

  characterized by the use of one or more absolute position encoders.

  9) An apparatus for printing according to claim 1 and characterized by a solidarise mounting of the axis of said encoder with the drive pulley of said translator. An apparatus for printing comprising: a frame capable of accommodating the plurality of printing components;

  displacement and position detection.

  A linear translator of pneumatic or hydraulic type.

  One or more printing devices secured to the part

mobile of said translator.

  A linear coding device disposes along the said translator and couples to a read cell secured to the said printing device. A rotary position encoding device mounts on the exe dne

pulleys of the said translator.

  11) An apparatus for printing according to claim 10 and characterized by the use of an incremental rotary encoder in combination

with a lineeire encoder.

  123 Apparatus for printing according to claim 1 0 characterized by compatibility with the mode

  intermittent thermal transfer printing.

  13) An apparatus for printing according to claim 10 characterized by compatibility with the mode

inkjet printing.

  14) An apparatus for printing according to claim 1 0 characterized by compatibility with the mode

laser drmpression.