EP1075391B1 - Economical printing method using an imaging tape and device for implementing said method - Google Patents

Description

The invention relates to printers such as are found in particular in fax machines.

More particularly, the invention relates to printers using a ribbon as a printing consumable. These can be printers by thermal transfer or by sublimation, that is to say printers in which are printed by ink transfer from a ribbon using a thermal source, comprising a thermal print head or again, by way of example, of mechanical transfer printers comprising a needle print head.

In a thermal transfer printer, to use this example again, the printing ribbon, used in roll, includes a support film in polyethylene coated with a layer of hot-melt ink. A roll food supplies virgin ribbon which is entrained, concomitantly with a print medium, in front of the thermal print head provided heating elements under activation of which ink is transferred from ribbon on the support, then the ribbon is rewound on a take-up roller intended to be thrown away. The ribbon is thus driven from the food roll to the take-up roller, passing in front of the print head.

With such printers, we are still wasting portions of ribbon virgins.

Document US 4,616,236 teaches a method for printing on X format print media images smaller than X / 2, at using a printing ribbon supporting a succession of ink ranges in X format. To print two print media in succession, concomitantly drives the support and the printing ribbon in front of a head in the forward direction, and we print the two supports using the two halves of the same ink pad, respectively, driving the ribbon backward between successive prints of two supports.

With such a printing process, the format of the image to be printed must be less than half the size of the ink pads.

The present invention first proposes to save printing ribbon whatever the format of the image to print.

To this end, the invention relates to a method for printing successively, by ink transfer, a plurality of images on at least one support printing using a printing ribbon, a process in which, for the printing of each image, we train concomitantly the ribbon and the media in front of a printhead in a forward direction, and between two successive image prints, we drag the ribbon, in the reverse direction, the along a displacement such as one prints the following image using at least of a remaining printing area of a portion of ribbon previously used, process characterized by the fact, when printing a plurality of print media shifted by a spatial interval determined the bottom edge of each of the supports from the top edge of the next support, we drive the ribbon in the return direction, between successive impressions of support, along at least equal displacement said spatial interval.

By "ink transfer" is meant both the thermal transfer stricto sensu that sublimation, i.e. any ink transfer process by a thermal source of a printing ribbon on a support printing.

Advantageously, for printing each image, the ribbon is unrolled of a food roll and we rewind it on a take-up roll, and between two successive prints, unroll it from the take-up roll and rewinds on the food roll.

The invention also relates to a device for printing successively, by ink transfer, a plurality of images on at least one support printing using a printing ribbon, for the implementation of the method according to claim 1, comprising a housing for receiving a food roll of printing ribbon, a receiving a print ribbon take-up roll, one head printing, ribbon drive means arranged to drive the ribbon, in a forward direction, from the food roll to the take-up roll passing in front of the print head, means for driving the support arranged to drive the support in the forward direction in front of the head printing, and means arranged to drive the ribbon in the direction return, device characterized in that it comprises a single motor ribbon drive in the forward direction and in the reverse direction, wheel mounted free, to drive the food roll in the return direction, rotary drive means, mounted freewheeling, to drive the take-up roller in the forward direction, means for slowing down the drive of the food roller driven in the forward direction and means to brake the drive of the take-up roller driven in the return direction.

• la figure 1 représente une vue de côté schématique d'un système d'engrenage de l'imprimante pour l'entraínement du ruban d'impression et d'un support d'impression, selon la forme de réalisation particulière;
• la figure 2 représente un schéma bloc fonctionnel de l'imprimante, selon la forme de réalisation particulière ;
• la figure 3 représente une vue de dessus d'une portion de ruban d'impression, selon la forme de réalisation particulière et
• la figure 4 représente une vue de dessus d'une portion de ruban usagée de la figure 3.

The invention will be better understood using the following description of a particular embodiment of the printing method of the invention, and of a particular embodiment and of a variant of the printer as well as of a particular embodiment of the printing ribbon, for implementing the method, with reference to the appended drawing in which:

• Figure 1 shows a schematic side view of a gear system of the printer for driving the printing ribbon and a printing medium, according to the particular embodiment;
• FIG. 2 represents a functional block diagram of the printer, according to the particular embodiment;
• FIG. 3 represents a top view of a portion of printing ribbon, according to the particular embodiment and
• FIG. 4 represents a top view of a portion of used tape from FIG. 3.

In the particular example of the description, the printer belongs to a fax. This is a thermal transfer printer including a thermal print head 1, a housing for receiving a roll ribbon food, receiving housing for a take-up roller ribbon, a magazine 5 for the input of print media to be printed, in the kind of reamed sheets of paper, a sheet outlet store after printing, a separation edge 4 and a mechanism 7 for printing ribbon 10 and a backing sheet printing. Both rolls, food and receiver, are supported by two respective axes 2 and 3 which are both mounted free in rotation. A pinion 38 and a pinion 39 are fixed respectively on the axis 2 and on axis 3.

A writing roller 27, mounted to rotate freely, is slightly in contact against the thermal head 1 and supports a pinion 28, integral and coaxial.

For the sake of clarity, it should be noted at the outset that all of the axes of the printer are perpendicular to the same plane which is that of Figure 1.

The printing ribbon 10 (FIG. 3) comprises a polyethylene film 11 supporting a printing layer 12 here comprising a plurality of hot-melt ink pads 12a, 12b, 12c in cyan, magenta, yellow colors and black, arranged one next to the other along the length of the ribbon 10. The film 11 also supports a marking area 13 located on the along the longitudinal edge of the tape 10, in the vicinity of the layer 12, and containing a plurality of positioning indications, here black bars, placed side by side along the edge of the ribbon 10, at regular intervals.

• entraíner le ruban d'impression 10 dans un sens aller, en le débitant du rouleau alimentaire et le rembobinant sur le rouleau récepteur, et
• entraíner dans le même sens aller la feuille support du magasin d'entrée 5 au magasin de sortie 6,
  en faisant passer la feuille et le ruban 10 concomitamment devant la tête thermique 1.

The drive mechanism 7 is arranged, when printing an image on a support sheet for:

• drive the printing ribbon 10 in a forward direction, delivering it from the food roll and rewinding it on the take-up roll, and
• drive in the same direction go the support sheet from the input store 5 to the output store 6,
  by passing the sheet and the ribbon 10 concomitantly in front of the thermal head 1.

The drive mechanism 7 is also intended to drive the ribbon 10 in the reverse direction in front of the thermal head 1, delivering it of the take-up roller and rewinding it on the food roll, as this will be explained later.

By definition, the forward direction of a pinion, a roller or any other rotary element of the printer is the direction of rotation of this element corresponding to the direction in which the ribbon is driven from the roll food with the take-up roller and / or in the sense that a sheet is driven from the input magazine 5 to the output magazine 6. The return direction is of course the opposite direction to this forward direction.

The mechanism 7 includes a single motor 18 for rotational drive of a motor shaft 19, in the forward direction and in the reverse direction, and a system gear for driving the ribbon 10 and a support sheet printing.

The gear system includes in particular, for the drive of the ribbon 10 in the forward direction, a pinion 33 mounted in free wheel. The pinion 33 engages, via a differential, with the pinion 39 of the axis 3 roller support receiver and is arranged to be rotated in the forward direction by the motor shaft 19, via a set of drive pinions not shown. Under the action of the rotational drive in the forward direction of the motor shaft 19, the take-up roller is thus intended to be driven in rotation in the forward direction, via the pinion set intermediate, pinion 33 and pinion 39.

For driving the ribbon 10 in the return direction, the gear system includes two pinions 29 and 32 integral and coaxial. Pinion 32, mounted in freewheel, meshes with the pinion 38 of the axis 2 support of the food roller and the pinion 29 meshes with the pinion 28 meshed itself a pinion 23. This, mounted free to rotate, is meshed with a pinion 34 arranged to be rotated by the drive shaft 19, by through the set of drive gears not shown. The pinion 34 and the pinion 33 are coaxial.

Thus, the food roller is intended to be rotated in the return direction, under the action of the rotary drive of the motor shaft 19 in the return direction, via the gear chain comprising the intermediate gear set and the gears 34, 23, 28, 29, 32 and 38, as will be explained later.

For driving a printing sheet, the gear system includes an axis 24 for loading the sheet, adjacent to the input magazine 5, and an axis 25 for ejecting the sheet, adjacent to the outlet magazine 6. The axis 24 and the axis 25 respectively support loading rollers and ejection rollers. A pinion 40 and two coaxial and integral pinions 41, 35 are respectively fixed on the loading axis 24 and on the ejection axis 25. The two pinions 41 and 40 are meshed with a pinion 26.

The drive pinion 23 is thus arranged to drive the axis 25 support of the ejection roller in the forward direction, via the pinion 35, and, under the action of the rotational drive of the pinion 41, the pinion 26 is intended to be driven in rotation and to drive itself in rotation in the direction go the axis 24 support of the load rollers, via the pinion 40.

The axis 25 of the ejection roller is mounted freewheeling so that it cannot to be rotated only in the forward direction corresponding to the direction ejection, which avoids any risk of inadvertent loading of a sheet by the outlet store 6.

Two non-return systems 30, 31 are mounted respectively on the pinion 38 of axis 2 of the food roller and on the pinion 39 of axis 3 of the roller receiver. The non-return system 30 of the food roller is intended for apply a resistant torque to the pinion 38 when the latter is driven in rotation in the forward direction. The non-return system 31 of the take-up roller is intended to apply a resistant torque to the pinion 39 when it is driven in the return direction. Thanks to this, the ribbon is always tense when it is driven in the forward direction or in the reverse direction.

The printer further includes a page storage memory 14 image of received faxes, a block 15 for digital analysis of the images of fax stored as data in memory 14, a sensor 16 for detecting sheets of print media, a sensor 17 for detection of indications of positioning of the printing ribbon 10 and a control block 21, in this case a microprocessor, to which all the electrical and electronic components of the printer (head 1, sensors 16-17, block 15, motor, etc.) are connected.

The thermal head 1 is here arranged to print the images line by line. By definition, we call "the printing line" of the thermal head 1, the virtual line 8 along which the thermal head 1 prints the lines successive of an image on a printing sheet scrolling in front of it.

The sensor 16 is provided for detecting the presence of a sheet to be printed passing through the printing line 8. The sensor 17 is intended to detect the indications for positioning the printing ribbon 10 when the latter passes through the printing line 8.

• examiner les lignes composant les pages d'image stockées dans la mémoire 14, afin de déterminer, pour chaque page d'image, les lignes, les zones, de la page vides d'image et les lignes d'image,
• déterminer les zones d'impression restantes d'une portion de ruban précédemment utilisée et
• calculer la longueur de rembobinage de ruban 10 entre deux impressions successives d'image.

The digital analysis block 3 includes application software designed to:

• examining the lines making up the image pages stored in the memory 14, in order to determine, for each image page, the empty image lines, zones, of the page and the image lines,
• determine the remaining printing areas of a previously used portion of ribbon and
• calculating the length of rewinding of tape 10 between two successive image prints.

The terms "image line" and "empty image line" are intended to denote respectively a line containing, in whole or in part, image points and a line without image points.

A "portion of ribbon previously used" means a portion of the ribbon 10 passed in front of the print head 1, in the forward direction, in other words after a print pass.

The printer further comprises a man-machine interface 20 with an input keyboard and a display screen The input keyboard includes an economical print button for controlling economical printing of images in memory 14, as well as a normal print key to print in mode normal.

The method for successively printing, by ink transfer, in a manner economical, a plurality of images here on a plurality of support sheets using the printing ribbon 10, corresponding to the operation of the printer will now be described.

The images to be printed, which are here image pages, are stored under form of data in memory 14.

In order to economically print the image pages contained in the memory 14, an operator presses the economic printing key on the input keyboard (20).

Printing image pages

For printing each image page, under the control of the block of control 21, the motor shaft 19 is rotated in the forward direction by the motor 18 and drives the pinion 33, via the set of pinions previously mentioned intermediary. The pinion 33 drives itself in rotation axis 3 of the take-up roller, and therefore the take-up roller itself, in the forward direction, via the pinion 39.

Under the action of the drive of the motor shaft 19, the pinion 23 is driven in rotation, in the forward direction, through the set of gears and the pinion 34. The pinion 23 rotates in the forward direction, the roller writing 27, through its pinion 28, as well as pinion 41 by through the pinion 35. The pinion 41 rotates the pinion 26 which itself drives the pinion 40 of the axis 24 of the loading roller, in the forward direction. The ejection roller 25 and the loading roller 24 are thus rotated respectively in the direction of ejection and in the direction of loading.

It will be emphasized that the pinion 32 being mounted in free wheel, it is not rotated under the action of the shaft rotational drive motor 19 in the forward direction.

The food roller is rotated by the effort of traction exerted by the tape 10. The non-return system 30 applies a resisting torque on pinion 38 of axis 2 of the food roller, so that the rotation of the food roller is slowed down. The food roll thus rotates slower than the take-up roller and, as a result, the ribbon 10 tightens.

Under the action of the rotational drive of the loading axis 24 and the ejection axis 25, a print sheet 100 is driven in the forward direction from entrance store 5 to exit store 6, passing in front of the head thermal 1 and, concomitantly, under the action of the rotation of the roller receiver and food roll, the ribbon 10 is driven in the direction go from the food roll, from which it is unwound, to the take-up roll, on which it is wound, passing in front of the thermal head 1.

The sheet 100 and the ribbon 10, concomitantly trained in front of the head thermal 1, are pressed against it by the writing roller 27 and, under the activation of the heating elements of head 1, ink is transferred from ribbon 10 on sheet 100 and the image page is thus printed, line by line, on sheet 100.

Rewinding the printing ribbon

On the command of the economic printing key, the analysis block 15 examines the image pages contained in the memory 14 in the form of data.

It will be noted at the outset that the top and bottom of an image page, that is to say the top and bottom of the page, are by definition the parts of the page respectively printed successively by the head thermal 1.

For printing each of the successive image pages to be printed, the block 15, under the control of control block 21, examines, from top to bottom, the successive lines composing the page to be printed. For each line, the block 15 determines if it is a picture line, and therefore if it is a line to print in whole or in part, or if it is an empty line of image, in order to deduce if the page to be printed contains an upper zone, a band upper image void. If applicable, block 15 counts the number of empty image lines making up the empty image top area and, each line having a given height, evaluates the height of the empty upper area image.

By "height" is meant the dimension along the direction perpendicular to that of the lines making up the image page.

For printing each of the successive pages, except for the first page, the analysis block 15, under the control of the control block 21, also examine, from bottom to top, the lines making up the image page previous page (i.e. the previously printed page), kept in the memory 14. Block 15 determines for each line, whether it is a line image or if it is an empty line of image in order to deduce if the page previous contains an empty image bottom area. If applicable, the block 15 counts the number of empty image lines composing the lower zone blank image and, each line having a given height, evaluates the height of the bottom empty image area.

Note here that for successive prints of two image pages on two print sheets, the printer drives one after the other two print sheets in front of thermal head 1, shifting one of the other of an "interpage". This is a determined spatial interval from which shifts the lower edge and the upper edge respectively by two sheets successively driven in front of the thermal head 1 for printing. A such interpage consumes an equivalent length of ribbon.

Between the successive prints of two image pages, block 15 evaluates a rewinding length, i.e. a length of tape that should be rewound around the food roll. For this, block 15 add, if necessary, the height of the interpage between the sheet previously printed and the sheet to be printed, the height of the area upper blank image of the page to print and the height of the area lower image void from the previous page, and subtracting from that a predefined tolerance height.

In the case where the rewinding length is not zero, the motor shaft 19, between successive prints of two image pages and under the control of the control block 21, is rotated in the direction return by the motor 18 until the ribbon 10 of the take-up roll is unwound, which is simultaneously rewound on the food roll, estimated rewinding length.

Under the action of the rotational drive of the motor shaft 19 in the direction return, the pinion 34 is rotated in the return direction and drives itself in rotation the pinion 23 in the return direction. The training of pinion 23 causes the rotational drive of pinion 28 which causes turn the pinion 32, via the pinion 29. And finally, under the action of the rotational drive of the pinion 32, the pinion 38 of the axis 2 of the food roller is rotated in the return direction.

It will be emphasized that the pinion 33 and the ejection axis 25 being mounted on a wheel free, they are not rotated under the action of the drive in rotation of the motor shaft 19 in the return direction.

The take-up roller is rotated in the return direction, under the tensile force exerted by the tape 10. In addition, the non-return system 31 applies a resistant torque to the axis 3 roller support receiver so that it is braked and turns slower than the roller food. Thanks to this, the ribbon 10 is well tensioned during its rewinding on the food roll.

During the drive of the ribbon 10 in the return direction, the sensor 17 detects and counts print ribbon positioning bars 10 passing through the printing line 8 of the thermal head 1 and, the bars being separated from each other by a given and fixed interval, evaluates the length of which the ribbon 10 is effectively rewound. When the effective rewinding length of the tape 10 is substantially equal to the evaluated rewinding length, the control block 21 commands the stop motor 18.

We could also consider using a printing ribbon without positioning indications. In this case, block 15 would convert the height rewind rated in number of revolutions of motor 19 and this one would rotated in the reverse direction substantially by the number of turns thus evaluated.

A more sophisticated variant of the economical printing process of the invention differs from the embodiment of the process described above only by what will now be described.

The printer comprises, in addition to the elements described above, a working memory intended to contain the positions of printing lines and unusable lines of previously used tape portions as well that the positions of image lines and empty image lines of pages image to print.

It will be noted at the outset that the positions of the lines of the ribbon are defined by relation to the print line of the writing head and the positions of the lines of the image page are defined relative to the top line of the page to to print.

The terms "print lines" and "unusable lines" mean here respectively designate blank lines of ribbon 10 and lines of ribbon already used, in whole or in part, for printing image points.

• les lignes de la page à imprimer afin de déterminer les positions des lignes d'image et celles des lignes vides d'image dans la page, et
• les lignes de la portion de ruban précédemment utilisée, ici pour l'impression de la page précédente, afin de déterminer les positions des lignes d'impression restantes et celles des lignes inexploitables cette portion de ruban précédemment utilisée.

For the printing of each image page, the digital analysis block examines:

• the lines of the page to be printed in order to determine the positions of the image lines and those of the empty image lines in the page, and
• the lines of the portion of ribbon previously used, here for printing the previous page, in order to determine the positions of the remaining printing lines and those of the lines which cannot be used with this portion of ribbon previously used.

Note here that by printing an image on a print sheet, by ink transfer from the ribbon 10 onto the sheet, we also print "in negative 'image on ribbon 10. Therefore, to examine the lines of the portion of ribbon previously used for printing a page image, the digital analysis block analyzes the lines of this page image. The unusable lines and the printing lines of the portion of ribbon used correspond respectively to image lines and lines image blanks from the image page previously printed with this portion of ribbon.

The positions of the image lines and the empty image lines of the page to be print and those of the print lines and unusable lines of the previously used portion of ribbon is saved in memory of work.

The digital analysis block compares, by their respective positions, the image lines of the page examined and the remaining print lines of the portion of ribbon previously used, to determine if the lines image of the page under review can at least in part be printed at using the remaining print lines from the ribbon portion previously used, separated from the portion of ribbon not yet used by at least one unusable line.

If this is the case, the digital analysis block determines the length of ribbon rewind, i.e. the length of ribbon along which it should drive the tape in the return direction, by unwinding the roll receiver and rewind on the food roll, so as to position suitably the printing ribbon in relation to the printing line of the thermal head. The ribbon is correctly positioned when the lines of the remaining portion of ribbon previously used, for printing image lines of the page to be printed, go to across the thermal head printing line for printing these image lines on a print media sheet.

Note that this variant of the economical printing process allows to print negatively on a printing ribbon images, or image portions, separated from the portion of ribbon not yet used by a another image, or another image portion, previously printed. The figure 4 illustrates such an example in which an element is first printed oval 101 then a triangular 102 element using the portion of ribbon already used. Arrows 36 and 37 indicate respectively the forward direction and the return direction of the ribbon.

The oval element 101 is printed in negative during a first ribbon printing pass in the forward direction 36 in front of the thermal head, then the ribbon is driven backward 37 and, within one second ribbon printing pass in the forward direction 36 in front of the thermal head, the triangular shaped element 102, located in FIG. 4 upstream of the oval-shaped element 101 in the forward direction 36 is printed.

In the description which has just been made of the two embodiments of the printing process, consider that a line of a portion of ribbon previously used is a print line, in other words a line can be used to print an image line, if this line of the ribbon is blank.

In another variant, lines of the printing ribbon are used slightly depleted in ink to print image lines. The block analysis tool assesses the ink surface density of each line of the portion of ribbon previously used, compares it to a predefined threshold and, in the case where the density evaluated is greater than the threshold, the analysis block considers that said line of the ribbon is a printing line, usable for print an image line. For the evaluation of the surface density ribbon lines, the digital analysis block evaluates the density of image points of the image line previously printed using this ribbon line.

Claims (10)

1. Method for successively printing, by ink transfer, a plurality of images on at least one print medium (100), using a print tape (10), a method in the course of which, in order to print each image, the tape (10) and the medium (100) are driven simultaneously in front of a printing head (1) in a forward direction, and between two successive instances of image printing, the tape (10) is driven in the reverse direction along a travel path such that the next image is printed using at least one remaining printing zone of a previously used portion of tape, method characterised by the fact that when a plurality of printing media are printed by offsetting by a predetermined spacing the lower edge of each of the media from the upper edge of the following medium, the tape (10) is driven in the reverse direction between each successive printing of the medium, along a travel path at least equal to said spacing.
2. Method according to claim 1, wherein, in order to print each image, the tape (10) is unwound from a feed roller and rewound onto a receiving roller, and between two successive instances of printing, the tape is unwound from the receiving roller and rewound onto the feed roller.
3. Method according to one of claims 1 and 2, wherein, when pages of images are being printed, one determines, for each page to be printed, whether the preceding page includes a lower zone with no image and, if need be, the height of said lower zone is estimated and, between the respective printing of two successive pages, the tape (10) is driven in the reverse direction along a travel path at least substantially equal to the height thus estimated.
4. Method according to one of claims 1 to 3, wherein, when pages of images are being printed, one determines for each page whether it includes an upper zone with no image and, if need be, the height of said upper zone is estimated and, before the page is printed, the tape (10) is driven in the reverse direction along a travel path at least substantially equal to the height thus estimated.
5. Method according to one of claims 1 to 4, wherein, for each image to be printed, image zones are determined, a previously used tape portion is broken up into printing zones and unusable zones, the image zones and the printing zones of the previously used portion of tape are compared so as, if need be, to drive the tape in the reverse direction along a travel path such that, in order to print at least one zone of the image to be printed, a printing zone of the used tape portion is used which is separated by an unusable zone from a tape portion which has not yet been used.
6. Method according to claim 5, wherein the tape is broken up into a plurality of zones, the surface density of ink on each of these zones is assessed and in the case where this density is greater than a predetermined threshold, said zone is considered to be a printing zone.
7. Method according to one of claims 1 to 6, wherein since the tape (10) supports a marking zone (13) including indications for positioning the tape, said indications are detected and, depending on these, the tape (10) is positioned in relation to the printing head (1).
8. Device for successively printing, by ink transfer, a plurality of images on at least one print medium (100) using a print tape (10), to implement the method according to claim 1, said device comprising a receiver to accommodate a feed roller for imaging tape (10), a receiver to accommodate a roller to receive the print tape (10), a printing head (1), means (18, 19, 33, 39) for driving the tape, arranged to drive the tape (10) in a forward direction from the feed roller to the receiving roller, passing in front of the printing head (1), means (18, 19, 34, 23, 35, 41, 26, 40) for driving the medium (100) arranged to drive the medium (100) in the forward direction in front of the printing head (1) and means (18, 19, 34, 23, 28, 29, 32) arranged to drive the tape (10) in the reverse direction, a device characterised by the fact that it comprises a single motor (18) for driving the tape (10) in the forward and reverse directions, rotary driving means (32) in a freewheel mounting, to drive the feed roller in the reverse direction, rotary driving means (33) in a freewheel mounting, to drive the receiving roller in the forward direction, means (30) to brake the driving of the feed roller when it is driven in the forward direction and means (31) to brake the driving of the receiving roller when it is driven in the reverse direction.
9. Device according to claim 8, comprising means for tautening the tape when it is driven in the reverse direction.
10. Device according to one of claims 8 and 9, wherein the means (18, 19, 34, 23, 35, 25, 26, 24) for driving the tape (10) in the reverse direction are arranged to unwind the tape (10) from the receiving roller and to rewind it on the feed roller.

Images