FR2835777A1 - DEVICE FOR CONTINUOUSLY DRIVING A MEDIA TO BE PRINTED FOR A LASER PRINTER, LASER PRINTER EQUIPPED WITH SAID DEVICE AND METHOD FOR CONTROLLING SAID DEVICE - Google Patents

Abstract

- The object of the invention is a device for driving a support (12) to be printed for a laser printer (10), characterized in that it comprises two assemblies, arranged on either side of the support ( 12), each comprising at least one pair of wheels, a first wheel disposed below the support and a second wheel above, at least one of the two wheels being driving. Application to a laser printer capable of printing a support comprising a plurality of printing areas (22) separated by interstices (24) or marking means and comprising transfer means (14), means (16) for driving said support (12) and means (18 ) drying, characterized in that it comprises friction type drive means (16) according to the invention.

Description

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CONTINUOUSLY DRIVING DEVICE OF A PRINTED MEDIUM FOR A LASER PRINTER, EQUIPPED LASER PRINTER
SAID DEVICE AND DRIVING METHOD OF SAID DEVICE.

 The present invention relates to a device for continuously driving a print medium for a laser printer, to the printer equipped with said device as well as to a control method more particularly suited to this type of drive device. .

 Application US-4.870. 434 describes a laser printer with a continuous supply of the medium to be printed. The latter comprises, in the direction of travel of the support to be printed, transfer means making it possible to deposit on the support of the ink, means for driving said support and drying means in the form of a drum.

 These drive means consist of two substantially symmetrical assemblies, arranged on either side of the support, each comprising a strip running around two parallel axes and carrying a plurality of pins capable of being housed in holes made at the level of the side edges of the print media. A motorization is also provided for driving in rotation at least one of the shafts, thus ensuring the rotational movement of the spike strips capable of ensuring the movement of the support to be printed.

 The transfer and drying means being separate, it is necessary to control said means in a separate manner, the latter not acting at the same time on the same area of the support, and to synchronize said means when the support is scrolled.

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 To this end, coding wheels are arranged on the axes supporting and rotating the spike bands, said wheels being capable of generating a signal synchronized with the rotational movement of the shafts supporting the spike bands, and therefore with the theoretical scrolling movement media to be printed.

 This printer can be used to print continuous media in the form of a strip on which labels are arranged. Thus, the printer is capable of reproducing a pattern corresponding to each of the labels on successive zones. Also, it is necessary to locate the beginning and the end of the labels, to trigger the operations of the transfer and drying means adequately.

 For this purpose, the printer further comprises means for detecting the head or the free end of the support to be printed which corresponds substantially to the edge of a zone to be printed as well as means for informing the control means on the dimension according to the direction of scrolling of the areas to be printed or labels.

 Thus, knowing the speed of travel of the support to be printed thanks to the coding wheels, the size of the labels and the position of the head of the support at an instant T called origin, it is possible to control the transfer means and the drying drying means. so as to arrange the printed areas correctly in relation to the labels.

 However, this printer is not entirely satisfactory, because it is necessary to provide a specific support, perforated at its lateral edges so as to be driven. Furthermore, the fact of controlling the rotational movement of the drive shafts of the spike strips, and not the movement of the support to be printed, does not make it possible to detect any problems of movement of said support to be printed.

 Also, the present invention aims to overcome the drawbacks of the prior art, by proposing a new drive device for a laser printer of simple design, easily adaptable to existing machines and capable of continuously driving a support to be printed. more reliably. The invention also aims to propose a laser printer equipped

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 of said drive device and of new means of controlling the movement of the support to be printed ensuring a simpler and more reliable control of the transfer and drying means.

 To this end, the subject of the invention is a laser printer capable of printing a support comprising a plurality of areas to be printed separated by interstices or marking means and comprising transfer means, means for driving said support and drying means characterized in that it comprises friction type drive means and means for controlling the movement of the print medium capable of detecting the interstices or the locating means.

 Advantageously, the means for controlling the running are in the form of an optical fork.

 According to a preferred embodiment, the device for driving the support to be printed comprises two assemblies, arranged on either side of the support, each comprising at least one pair of wheels, a first wheel disposed below the support and a second wheel above, at least one of the two wheels being driving.

 Advantageously, each set includes two pairs of wheels.

 According to another characteristic, the axes of rotation of the wheels of the same pair are not parallel so as to obtain a greater linear speed of the support to be printed at the free edge of said support in order to tension it between the two sets of wheels. .

 According to a preferred embodiment, each assembly comprises a wheel support consisting of two parts, a first part comprising bores capable of allowing axes driven in rotation and carrying the first wheels, and a second part carrying axes on each of which the second wheels are attached, said second part being articulated with respect to the first part along an axis of rotation substantially parallel to the direction of travel.

 Preferably, each assembly comprises means for adjusting the pressure exerted by the wheels on the support to be printed, comprising a lever arm of which a first end is connected to the second part of the support

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 wheel and the second end extends in the direction of the middle part of the support to be printed, an adjusting screw being provided at the second end on which an element of the carcass of the printer can bear.

 The invention also relates to a method for controlling a laser printer according to the invention, characterized in that instructions and signals, in particular a video signal, are transmitted to the transfer and drying means in synchronization with respect to a signal generated by the scroll control means capable of detecting the interstices or the tracking means.

 Other characteristics and advantages will emerge from the following description of the invention, description given by way of example only, with reference to the appended drawings in which: - Figure 1 is a schematic view of a printer according to the invention, - Figure 2 is a top view of the drive device according to the invention, - Figure 3 is a side elevational view of part of the drive device, and - Figure 4 is a diagram showing the signals used to control the printer.

 In Figure 1, there is shown a laser printer 10 materialized by a dotted carcass comprising, in known manner, in the direction of travel of a support 12 to be printed, transfer means 14, means 16 for driving said support 12 and means 18 for drying.

 The transfer and drying means are not described in detail because they are within the reach of those skilled in the art and do not constitute essential elements of the invention. Furthermore, the relative positions of the different transfer, drying and drive means are not significant and given only by way of example, the latter being able to be arranged in a different order.

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 This printer is more particularly suitable for printing a support 12 in the form of a strip 20 on which are arranged one after the other labels 22 or areas to be printed, the latter being characterized in particular by a length L in the direction of scrolling and being separated by a gap 24.

 According to the invention, the printer comprises friction type drive means 16 and means 26 for controlling the movement of the support to be printed, separated from the drive means and capable of detecting the interstices 24 between the labels 22.

 Thanks to these friction drive means 16, all types of paper can be printed. Indeed, it is no longer necessary to use a specific support with holes at the side edges.

 Furthermore, the fact of providing means 26 for controlling the movement of the support to be printed capable of detecting the gaps between the areas to be printed makes it possible to obtain a simpler and more reliable control since the transfer and drying means are no longer controlled relative to the movement of the drive means but directly relative to the movement of the support.

 The means 26 for controlling the scrolling can be arranged indifferently inside or outside the carcass of the printer, and at any position in the direction of scrolling, the latter being preferably arranged as close as possible drive means 16. By way of example in FIG. 1, they are arranged upstream of the transfer means 14.

 According to a particular embodiment, the means 26 are in the form of an optical fork, photosensitive cell or the like, capable of emitting a signal 28, illustrated in FIG. 4, identifying the interstices 24, for example in the form of 'a niche function. This type of photosensitive cell makes it possible to detect the interstices in the two directions of travel, a movement in the rear direction being desirable at each start of printing in order to limit the losses of support, the transfer and drying means being distant.

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 The friction drive means 16 are shown in FIGS. 1 to 3. They consist of two assemblies 30 arranged on either side of the support 12. Each assembly 30 comprises at least one pair of wheels, a first 32.1 disposed below the support and a second 32.2 above, at least one of the two wheels being driving.

 Advantageously, each assembly 30 comprises two pairs of wheels, as illustrated in FIGS. 1 and 2.

 According to a preferred embodiment illustrated in detail in Figures 2 and 3, the first wheels 32.1 are each mounted respectively on an axis 34 driven in rotation by a motorization, not shown, the axes 34 preferably being those which support the wheels d drive of the spiked bands.

 Each set 30 also includes a wheel support 36 for the second wheels 32.2, each disposed outside the wheel sets on either side of the support to be printed, comprising two bores 38 adjusted to the axes 34 and supporting two axes 40 each carrying one of the second wheels 32.2, the latter being mounted in free wheel.

Advantageously, the wheel support comprises two parts a first part 36.1 comprising the bores 38 and a second part 36.2 carrying the axes 40, articulated with respect to the first part 36.1 along an axis 42 of rotation substantially parallel to the direction of travel, means
44 for adjusting the pressure exerted by the wheels on the support to be printed being provided.

 Preferably, the axes 40 supporting the wheels 32.2 are slightly inclined with respect to the axes 34 so as to obtain a greater linear speed of the support to be printed at the free edge of said support in order to tension it between the two sets of wheels 30.

 According to an embodiment illustrated in FIG. 3, the means 44 for adjusting the pressure comprise a lever arm 46 of which a first end is connected to the second part 36.1 of the wheel support and the second end extends in the direction of the middle part of the support to be printed.

 Thus, by exerting by adjusting a force at the level of the second end, it

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 It is possible to adjust the pressure force exerted by the wheels on the support to be printed. Furthermore, the fact of exerting this force at the end of the lever arm 46 allows a more precise adjustment of the pressure.

 Advantageously, an adjustment screw 48 is provided at the second end allowing the pressure force of the wheels to be adjusted, by screwing it in or out. Preferably, an element of the printer casing, more particularly the cover, exerts a force on the head of the adjustment screw. Thus, with the cover open, the height of the screw 48 is adjusted. By closing the cover, the latter exerts a force proportional to the height of the adjustment screw 48.

 According to another characteristic of the invention, the wheelsets 30 arranged on either side of the support can translate on their support, in particular on the axes 34, in order to adjust their spacing and to adjust it to the width of the support to print.

 Preferably, the printer comprises a screen and a keyboard for viewing and entering data, not shown in the figures.

 The position of the means for transferring, drying, driving and controlling the scrolling being fixed and their relative positions being known, from the signal 28 emitted by the means 26 for controlling the scrolling, it is possible to control the means of transfer 14 and drying 18, the signals being transmitted synchronously with respect to signal 28, with possibly a regular offset.

According to the known control method, the instructions and signals are transmitted to the transfer means 14 and 18 for drying in an offset manner relative to a signal 50 generated by the drive means 16, corresponding to a virtual position of the interstices. This signal is produced by, on the one hand, the coding wheels which determine the speed of rotation of the axes.
34 and therefore the theoretical linear drive speed, and on the other hand, a sensor which detects the head of the support to be printed corresponding to a first gap. Thus, knowing the distance between two interstices which is informed by the user, the theoretical scrolling speed and the position of the head of the support to be printed at an instant T, it is possible to define at a

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 given location, the theoretical passage of the interstices in time, corresponding to a niche of the signal 50. If there were no difference between the actual scrolling speed and the theoretical scrolling speed, the signals 28 and 50 would be perfectly synchronized . However, as can be seen in FIG. 4, the signals 28 and 50 may not be synchronized, the corresponding slots of the two signals being able to shift more and more over time.

 According to the invention, the instructions and signals are transmitted to the transfer means 14 and 18 for drying in a synchronized manner with respect to the signal 28 generated by the means 26 for controlling the movement capable of detecting the interstices 24.

 Knowing the precise position of the means 26 for controlling the movement relative to the transfer and drying means and the speed of movement of the support, an offset is applied to the signal 28, a function of the relative positions, for the transmission of the signals to said transfer means. and drying.

 For example, to determine the scrolling speed, the user enters the distance separating two interstices, by dividing this distance by the time measured between two interstices, the scrolling speed is obtained. As a variant, this speed can be determined by knowing the speed of rotation of the drive wheels, in particular thanks to the coding wheels.

According to another characteristic of the invention, the position of the means
26 for controlling the scrolling being variable and unknown with respect to the transfer and drying means, the synchronization of the signals transmitted to said means 14 and 18 with respect to the signal 28 of the means 26 for controlling the scrolling takes account of the signal 50.

 As we have seen above, this signal 50 is a function of the speed of rotation of the axes 34 and of an origin TO, instant of passage of the head of the support to be printed at a given fixed position relative to said means transfer and drying. This signal 50 can be considered correct at the start, the first slots effectively corresponding to a gap. T1 is determined the time measurement between two slots of the signal

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 50, preferably the slots arranged on either side of the first slot of the signal 28. The time measurement between a slot of the signal 50 and the first consecutive slot of the signal 28 is determined T2 at the time of the first printing. We determine T3 = T1-T2.

 According to this method, the signals and instructions transmitted to the transfer and drying means, in particular the video signal, are synchronized with the signal 28 to which an offset T3 is applied.

 As a variant, it is possible to act on the drive means 16 to adjust the running speed and synchronize it with the signals and instructions transmitted to the transfer and drying means taking account of T3.

 According to another characteristic, it is possible to determine at any time during printing the offset T3 so as to synchronize almost instantaneously the movement of the support to be printed and the signals and / or instructions transmitted to the transfer and drying means.

 Thus according to this method, the video signal is synchronized reliably with the movement of the support and in particular the interstices. In addition, even if the drive means do not have a regular speed, the signals are always transmitted at the right time relative to the interstices, the latter being no longer synchronized with the drive means but with the control means. scrolling of the support to be printed. Finally, this arrangement makes it possible to precisely control and manage the printed surfaces and thus the consumables used.

 Of course, the invention is obviously not limited to the embodiment shown and described above, but on the contrary covers all variants, in particular with regard to the transfer means and the drying means.

 Finally, in certain cases, the interstices can be replaced by any suitable marking means making it possible to identify the separation between two successive printing areas, for example such as a light, a pre-cut line or a marking on the support. .

Claims (9)

1. Device for driving a support (12) to be printed for a laser printer (10), characterized in that it comprises two assemblies (30), arranged on either side of the support (12), each comprising at least one pair of wheels, a first wheel (32.1) disposed below the support and a second wheel (32.2) above, at least one of the two wheels being driving.  2. Device according to claim 1, characterized in that each assembly (30) comprises two pairs of wheels.  3. Device according to claim 1 or 2, characterized in that the axes of rotation of the wheels of the same pair are not parallel so as to obtain a greater linear speed of the support to be printed at the free edge of said support so to tension it between the two sets of wheels (30).  4. Device according to claim 2 or 3, characterized in that each assembly comprises a wheel support consisting of two parts, a first part (36.1) having bores (38) capable of allowing axes (34) driven in rotation and carrying the first wheels (32.1), and a second part (36.2) carrying axes (40) on each of which the second wheels (32.2) are attached, said second part (36.2) being articulated relative to the first part (36.1 ) along an axis (42) of rotation substantially parallel to the direction of travel.  5. Device according to any one of claims 1 to 4, characterized in that each assembly comprises means (44) for adjusting the pressure exerted by the wheels (32) on the support (12) to be printed.  6. Device according to claims 4 and 5, characterized in that the adjustment means (44) comprise a lever arm (46) of which a first end is connected to the second part (36.2) of the wheel support and the second end extends towards the middle part of the support to be printed, an adjustment screw (48) being provided at the second <Desc / Clms Page number 11>  end on which an element of the printer casing can bear.  7. Laser printer capable of printing a support comprising a plurality of printing areas (22) separated by interstices (24) or marking means and comprising transfer means (14), drive means (16) said support (12) and drying means (18) characterized in that it comprises friction type drive means (16) according to any one of claims 1 to 6 and control means (26) scrolling of the print medium capable of detecting the gaps (24) or the locating means.  8. Laser printer according to claim 7, characterized in that the means (26) for controlling the scrolling are in the form of an optical fork.  9. A method of controlling a laser printer according to claim 7 or 8 comprising means (16) of friction type drive according to any one of claims 1 to 6, characterized by the following steps consisting in: - defining a signal (50) in the form of slots, a function of the speed of rotation of the drive means (16) and of an origin TO, instant of passage of the head of the support to be printed at a given fixed position relative to said transfer and drying means, - determining T1 the time measurement between two slots of the signal (50), preferably the slots arranged on either side of the first slot of a signal (28) generated by the means (26 ) scroll control capable of detecting the gaps (24) or the locating means, - determining T2 the time measurement between a signal slot (50) and the first consecutive signal slot (28) made during the first printing , - determ iner T3 = T 1- T2, the signals and instructions transmitted to the transfer and drying means (14), in particular the video signal, or the speed of the drive means being synchronized taking account of the offset T3.