FR2808729A1 - THERMAL PRINTER - Google Patents

Abstract

The invention relates to thermal printers intended for printing on flat objects such as plastic or cardboard cards, for example loyalty cards or even smart cards, magnetic cards or any other similar medium. , the printer comprises a drive roller (14) movable relative to said print head (13), along a substantially vertical axis, so that the spacing between said roller (14) and said print head ( 13) is likely to vary depending on the thickness of said object (30) to be printed.

Description

Thermal printer.

  The invention relates to the field of thermal printers, whether by direct thermal printing or by thermal transfer. More particularly, the invention relates to thermal printers intended for printing on flat objects such as plastic or cardboard cards, for example, loyalty cards or even smart cards, cards

  magnetic or any other similar support.

  Thermal printers may work in two ways

  different principles: direct thermal printing and thermal transfer.

  In machines operating on the principle of direct thermal printing, the print head is brought directly into contact with the medium to be printed. It is specially coated so that the heat input causes a change in structure at its surface, generally resulting in a change in color. According to the second principle, known as thermal transfer, a film carrying ink is interposed between the print head and the object to be printed, the heat supply causing the transfer of

film ink on the object.

  In both cases, however, the print head has a line of local heating points, an electronic control selecting the points to

to print.

  In these printers, the print head can be vertical, flat or called "corner edge" (technology according to which the line of heating elements is located in a corner of the print head, the latter then being inclined by

vertical).

  These machines are commonly used for the personalization of cards, such as smart cards, magnetic cards or loyalty cards, identity badges, access cards, subscription cards or any

other similar support.

  In particular for loyalty cards, techniques have appeared recently, making it possible to erase data printed on a card and to

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  re-write new messages. It is therefore possible to visibly carry on a single loyalty card a point credit which changes, on the same subscription card, the characteristics specific to each customer or user of the card, promotional messages, or any other data likely to to be modified each time the customer visits. Currently, the thickness of the cards to be printed varies between 0.2 mm and 1.5 mm. A user of a card printing machine, for example a merchant, can therefore have several batches of cards, the thickness of the cards varying from one batch to another. At the same time, a user can choose a certain

  card thickness, while another will opt for a different thickness.

  It is therefore essential that the printers offered can support different card thicknesses and that, from an economic point of view, the printer manufacturer is not forced to offer as many printer models.

  that there are card thicknesses.

  In the state of the prior art, several solutions are proposed for making at least one member of the printer mobile in the direction of the card to be printed. Patent document EP-0 557 405 describes a printer comprising a print head mounted on a mobile carriage which makes it possible to raise or lower it perpendicular to the surface of the card. The carriage is mounted on a worm screw driven in rotation by a motor. The print head is also pivotally mounted to apply correctly over its entire length

against the card.

  Another type of known solution consists in using a pressure roller system, bending the card in the direction of the print head, motor rollers arranged on either side of the print head ensuring the

  scrolling of the card under the print head.

  In addition, some machines incorporate print heads that are movable in vertical translation, thanks to a system for guiding and motorizing the

head.

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  These solutions use complex mechanical, electrical and electronic assemblies, which in particular generate constraints of

  manufacturing affecting the price of machines.

  In addition, these prior techniques generate bulky units, often incompatible with user expectations. The invention particularly aims to overcome these drawbacks of

prior art.

  More specifically, the object of the invention is in particular to provide a printer capable of efficiently performing print jobs on

  flat objects of different thicknesses.

  In other words, the invention aims to provide the same machine to users having to print objects, for example cards, not having the same thickness, without the need to make adjustments.

on the machine.

  Another object of the invention is to provide a printer tolerant of

  slight variations in thickness on the same object to be printed.

  The invention also aims to provide such a printer using mechanical complexes that are not very complex and whose maintenance can

be assured simply.

  Yet another object of the invention is to provide a printer which

  or a reduced size compared to the machines of the prior art.

  The invention also aims to provide such a printer which

  either inexpensive to manufacture and assemble.

  These objectives, as well as others which will appear subsequently, are achieved using a thermal printer of the type comprising at least one print head and a motor roller capable of driving a flat object to be printed under said printhead. According to the invention, the printer comprises a motor roller movable relative to said print head, along a substantially vertical axis, so that the spacing between said motor roller and

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  said printhead may vary depending on the thickness of said

object to print.

  The roller thus performs a double function: it drives the card under the print head so that the head carries inscriptions line by line there, and it modifies its position according to the thickness of the card. According to another particularly advantageous characteristic. said print head is fixed, at least in vertical translation. No special setting or adjustment is therefore necessary. Very precise motorization devices coupled to different distance or limit switch sensors, generally

very expensive are thus avoided.

  According to an advantageous characteristic, the axis of rotation of said drive roller is located substantially vertical to the line of heating elements carried by said print head. This avoids multiplying the drive members of the card on either side of the print head. In this

  configuration, a single motorized roller is sufficient.

  According to a preferred characteristic, the bearings supporting said drive roller are coupled to elastic return means. By this simple and effective technique, the drive roller can move away from the print head under the thrust of the object to be printed, the elastic return means exerting a

  pressure under the object to hold it against the print head.

  Advantageously, said bearings are integral with an introduction plate. This plate can be useful in particular to facilitate the

  guiding and inserting the object between the drive roller and the print head.

  According to another characteristic, the printer comprises means for

  ensuring a predetermined spacing between said roller and said print head.

  This vacuum spacing favors the pinching of the card between the motorized roller driven in rotation and the print head. In the case of thermal transfer machines, this spacing also avoids the vacuum carrying of the film carrying the ink.

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  According to an advantageous characteristic, said means ensuring a predetermined spacing comprise at least one stop integral with said bearings or with the axis of said drive roller. The bearings, appropriately dimensioned, can in this case fulfill a double function consisting on the one hand of supporting the axis of the driving roller, and, on the other hand, coming to bear against the

  print head support when there is no object being printed.

  Other characteristics and advantages of the invention will appear more

  clearly on reading the following description of two embodiments

  of the invention, given by way of illustrative and nonlimiting examples, and of the appended drawings among which: - Figures la and lb illustrate a printer according to a first embodiment of the invention; - Figures 2a and 2b illustrate a printer according to a second embodiment of the invention; - Figures 3 to 8 show different stages of the operation of

the printer according to the invention.

  The general principle of the invention is therefore based on a simple and effective technique, consisting of making a motor roller mobile, the active generator of which is located substantially vertically above the line of heated heating points.

by the print head.

  In FIGS. 1a and 1b, a first embodiment of a printer according to the invention is shown, respectively viewed from the front and from the side in the

  direction of travel of an object to be printed.

  This printer comprises a frame or chassis 11, on which a support 12 is secured, on which the print head 13 is attached and fixed. The print head carries a line 131 of elementary heating points controlled electronically. In the example illustrated in these figures as well as in the following figures, the print head is vertical. It may however be preferred a head

  so-called "flat" or "corner edge" printing, without departing from the scope of the invention.

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  The axis 141 of the drive roller 14 is supported at each of its ends

  by bearings 151 provided for this purpose in an introduction plate 15.

  The insertion plate 15 forms a support facilitating the guiding of the object, in a substantially horizontal manner, towards the driving roller 14 and the print head 13. The operator thus just has to push the object in abutment on the platinum

introduction 15.

  The bearings and the insertion plate are placed so that the active generator of the drive roller (that is to say the generator capable of being in contact with an object to be printed to impose a displacement along the axis Y) and the line 131 of elementary heating points are substantially parallel to the axis X and perpendicular to the axis Z. The drive roller 14 thus positioned is sufficient in itself to impose a displacement on an object so that the object runs along its entire length under the

print head 13.

  The introduction plate 15 is guided in vertical translation on the chassis 11 by means known per se such as slides or any other

similar means.

  Elastic return means 16. such as springs with non-contiguous helical coils, are interposed between the introduction plate 15 and the frame 11, the axis of the springs being substantially coincident with the axis Z according to the view in FIG. 1b . These elastic return means are chosen to allow a stroke of the plate 15 on the chassis 11 at least equal to the range of thicknesses of the

  objects likely to be printed.

  At least one stop, and preferably two stops 17. are mounted on the axis 141, on either side of the drive roller 14. In the absence of an object to be printed, these stops 17 come to bear on the support. 12 of the print head, maintaining a minimum distance between the active generator of the drive roller 14 and the line 13 of elementary heating points. of the order of

0.15 mm.

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  This spacing is chosen so as to be slightly less than the smallest thickness of the objects likely to be printed. It allows the pinch necessary for driving the object between the motor roller 14 and the head

  13. Without this spacing, depending on the thickness of the object. the one-

  this could come up against the roller 14 and the print head 13, and force

  the operator to force its introduction somewhat.

  The motor means (not shown), ensuring the rotation of the

  motor roller 14, are integral with the introduction plate 15.

  By the means which have just been described, the printer of the invention easily and effectively accepts flat objects, such as loyalty cards

  or others, of different thicknesses.

  Indeed, by the joint action of the thrust of the operator and the motor of the roller 14, the object is introduced between the roller 14 and the print head while the plate 15 moves vertically as much as necessary depending the thickness of the object. The return means exert a pressure of the object against the print head 13, and bring the plate back into the waiting position at the end of printing, the stops 17 coming to bear on the support 12 of the print head . According to a second embodiment aimed at reducing the size of the machine, as shown in FIGS. 2a and 2b, the drive roller 14 is supported by a cradle 21. the uprights 211 of which have bearings

receiving axis 141.

  The uprights 211 comprise means for being guided in vertical translation, along slides, or any other similar means,

formed in the frame 11.

  The amounts are dimensioned to come to bear, in the absence of objects to be printed, on the support 12 of the print head and maintain the spacing between the active generator of the drive roller 14 and the line 13 of

  elementary heating points, as mentioned previously.

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  The springs 16 are interposed between the cradle 21 and the chassis 11, the axis of the springs being substantially coincident with the axis Z according to the view in FIG. 2b. In order to reduce the overall height, we could also consider adapting the cradle so that the springs 16 extend above

  of it, the springs 16 then working in traction rather than in compression.

  The introduction plate 15 of the first embodiment is removed from this second embodiment, which makes it possible to achieve the objective of reducing bulk. The driving means (not shown), ensuring the

  rotation of the drive roller 14, are here integral with the cradle 21.

  In the absence of the guide means that constitutes the plate 15 in the first embodiment, it is for the operator to introduce the object in a suitable manner, a slot being able to be made in the chassis to assist it in

His gesture.

  The different stages of printer operation according to

  the invention will now be detailed with the aid of FIGS. 3 to 8.

  Figure 3 shows the printer in the standby position. The stops 17 are in abutment against the support 12 of the print head 13, under the action of

  springs 16 slightly compressed. The drive roller 14 is stopped.

  In Figure 4, there is shown an object to be printed 30, such as a plastic card for example. placed on the insertion plate 15. Motor means are triggered to drive the roller 14 in rotation, either by the operator having a command to do this, or by a signal from

  of a device detecting the object 30 on the plate 15.

  As illustrated in FIG. 5. the object 30 is pushed onto the surface of the plate 15 until it comes into contact with the drive roller 14 and the head

13.

  Under the joint action of the operator's push on the object 30 and the rotation of the drive roller 14, the object 30 is introduced between the roller 14 and the print head, the roller 14, and therefore the platinum which supports it. moving

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  following arrow F (indicated in figure 6) as much as necessary depending on

  the thickness of the object 30. The stops 17 therefore deviate from the support 12.

  The springs 16 are therefore compressed a little more, and exert a thrust under the platinel5, so that the object is kept in pressure against the print head 13. As indicated in FIG. 7, the object 30 is then moved according to arrow F 'under the print head 13 under the action of the drive roller 14, the rotation of the roller being of the step-by-step type so that printing is carried out

line by line.

  In FIG. 8, the object 30 is in a position which precedes an end of the printing cycle. The object is then ejected from the printing area under

the action of the roller 14.

  The springs 16 then return the printer to the standby position

  (Figure 3), the stops 7 returning to bear on the support 12.

  Such a printer can therefore successively admit objects of different thicknesses without any particular intervention on the part of the user. The invention notably finds a particularly advantageous application for loyalty cards, the thicknesses of which may vary, depending on

  the material and the required rigidity, between 0.2 and 1.5 mm.

  The invention therefore proposes a solution fulfilling a new function with simple mechanisms which make it possible, in addition to the performance of the machine, to reduce the manufacturing costs of such printers compared to

the state of the art.

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Claims (7)

  1. Thermal printer of the type comprising at least one printhead (13) and a motor roller (14) capable of driving a flat object (30) to be printed under said printhead (13), characterized in that '' it comprises a drive roller (14) movable relative to said print head (13), along a substantially vertical axis, so that the spacing between said drive roller (14) and said print head (13 ) is likely to vary depending   the thickness of said object (30) to be printed.   2. Printer according to claim 1, characterized in that said head   printing (13) is fixed, at least in vertical translation.   3. Printer according to any one of claims 1 and 2, characterized in   that the axis of rotation (141) of said drive roller (14) is located substantially vertical to the line of heating elements (131) carried by said head printing (13).   4. Printer according to any one of claims 1 to 3, characterized in that   that the bearings (151, 211)) supporting said drive roller (14) are coupled to   elastic return means (16).   5. Printer according to any one of claims I to 4, characterized in that   that said bearings (151) are integral with an introduction plate (15).   6. Printer according to any one of claims I to 5, characterized in that   that it comprises means (17) for ensuring a predetermined spacing between   said roller (14) and said print head (13).   7. Printer according to claim 6, characterized in that said means (17) ensuring a predetermined spacing comprise at least one stop   integral with said bearings (151, 211) or with the axis (141) of said drive roller (14).