EP0100246B1 - Device for removing excessive developer material from the surface of a recording member - Google Patents

Device for removing excessive developer material from the surface of a recording member Download PDF

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Publication number
EP0100246B1
EP0100246B1 EP83400999A EP83400999A EP0100246B1 EP 0100246 B1 EP0100246 B1 EP 0100246B1 EP 83400999 A EP83400999 A EP 83400999A EP 83400999 A EP83400999 A EP 83400999A EP 0100246 B1 EP0100246 B1 EP 0100246B1
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EP
European Patent Office
Prior art keywords
air inlet
chamber
opening
orifice
suction
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP83400999A
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German (de)
French (fr)
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EP0100246A1 (en
Inventor
Jean-Jacques Binder
Bernard Cherbuy
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Bull SA
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Bull SA
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Filing date
Publication date
Application filed by Bull SA filed Critical Bull SA
Publication of EP0100246A1 publication Critical patent/EP0100246A1/en
Application granted granted Critical
Publication of EP0100246B1 publication Critical patent/EP0100246B1/en
Expired legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G19/00—Processes using magnetic patterns; Apparatus therefor, i.e. magnetography
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/095—Removing excess solid developer, e.g. fog preventing

Definitions

  • the present invention relates to a device for removing excess developer particles on the surface of a recording element.
  • a device for removing excess developer particles on the surface of a recording element finds more particularly, although not exclusively, its application in magnetic printing machines.
  • These printing machines In modern equipment used for information processing, more and more rapid printers are used in which the printing of the characters is carried out without for this calling upon the impact of types of relief printing on a sheet. of receiving paper.
  • These printing machines said to be without impact or even without transfer without striking, generally comprise a recording element, most often constituted by a rotary drum or an endless belt, on the surface of which one can form, electrostatic or magnetic, sensitive zones which correspond to the characters or images to be printed and which are capable of attracting solid particles of developer.
  • This recording element is then brought into contact with a sheet of receiving paper to allow the solid particles which are retained by the sensitized areas of the element definitively to be transferred to this sheet to be definitively fixed there.
  • a device of this type in which a mass of developer particles, placed in contact with the surface of the recording element and downstream of the particle application device, discharges the particles which adhere to this element outside of the sensitized zones, so that these discharged particles detach from the recording element and come to agglomerate with this mass.
  • a device does not give complete satisfaction to the use of the fact that it does not always ensure a complete electrical discharge of the particles and that it does not therefore make it possible to safely remove the particles of developer that remain on the recording element, outside of the sensitive areas thereof.
  • such a device cannot be used to remove excess particles on the recording element of an electrostatic printer, because this device would risk, by capturing the electric charges of this element, to erase the sensitized areas of it.
  • a device comprising a chamber which, connected to a pneumatic pressure member, is provided, opposite the surface of the recording element, with an opening through which the air which is sent under pressure into the chamber, this opening being dimensioned so that the exhaust of air takes place in the form of an air jet which strikes the surface and thus expels the developer particles in excess that are on this surface.
  • this device which gives good results, however has the disadvantage of spreading into the atmosphere the particles which have been expelled by the air jet, which generates pollution which always ends up being undesirable for people in the vicinity. near the machine.
  • This latter device which, operating like a vacuum cleaner, makes it possible to remove excess developer particles, without causing pollution of the atmosphere.
  • This latter device which has been described and represented in the French patent application published under No. 2, 322,395, comprises, on the one hand, a chamber, of generally cylindrical shape, provided with an inlet opening and an outlet opening, each of these openings being located at a respective one of the two ends of the chamber, the outlet opening being connected to a source of air depression, on the other hand a duct or nozzle, of constant section, which communicates, at one of its ends, with the entry opening of the chamber, the other end of this duct having a slit-shaped orifice disposed at a very small distance from the surface of the record item.
  • the orientation of the chamber is such that its generatrices are orthogonal to the direction of elongation of the orifice in the form of a slot in the duct.
  • the ratio of the cross-sectional area of the inlet opening to that of the chamber outlet opening is very small, that is to say less than 0.1, which ensures a flow rate. practically uniform air across the width of the chamber entry opening.
  • the developer particles which were sucked in were not always properly entrained during their passage through the chamber, so that an accumulation of particles ended up appearing on the walls of this chamber. , causing, in the long run, a significant decrease in the suction flow of the device and, consequently, a more or less significant obstruction of the duct
  • the present invention overcomes this drawback and proposes a device which makes it possible to efficiently suck up the excess developer particles which are on the surface of the recording element, without the particles thus sucked up accumulate elsewhere than on the filters that have been designed to collect them. As a result, the risks of fouling of this device are practically eliminated, which allows this device to operate under optimal conditions which, over time, do not undergo any modification.
  • the present invention relates to a device for removing from a surface on which a powder developer has been deposited, the excess developer particles which adhere to this surface, this device comprising a suction duct having an orifice at each of its two ends, one of these orifices, called the air inlet, having the form of a slit and extending parallel to said surface, in the immediate vicinity thereof, while the other orifice, said air outlet, is connected to a suction source by means of a cylindrical chamber integral with said suction duct, said device being characterized in that said chamber is arranged in such a way that its generators are parallel in the direction of elongation of the air inlet orifice of the duct, and in that the two opposite lateral parts of said chamber are each provided with an opening, one of which, called the air intake , leads to the open air, tand is that the other, called suction, communicates with said suction source, said chamber being further provided, on its cylindrical wall, with a third opening which corresponds with the air outlet
  • the printing machine part of which has been shown diagrammatically in FIG. 1, comprises a recording element which is constituted, in the example described, by a magnetic drum 10.
  • This magnetic drum 10 is driven in rotation, in the direction of the arrow F, by an electric motor (not shown).
  • the recording of information on this drum is carried out by a magnetic recording member 11 which is arranged near the external surface of the drum.
  • this recording member 11 is formed of an assembly comprising several magnetic recording heads which, placed one next to the other, are aligned parallel to the axis of rotation 12 of the drum 10.
  • Each of these heads generates, when it is repeatedly exited by an electric current, a variable magnetic field, which has the effect of creating magnetized domains or "magnetic points", on the surface of the drum which passes in front of the organ 11.
  • the instants of excitation of these heads are moreover established, in a known manner, so as to obtain on the surface of the drum sets of magnetized domains 13, called magnetized zones or latent magnetic images, the shape of which corresponds to that of the characters to be printed.
  • These magnetized zones 13 then pass in front of an application device 14 which is arranged below the drum 10 and which makes it possible to apply to the surface of the drum particles of a powdery developer contained in a reservoir 15.
  • the developer particles which are thus applied to the drum 10 adhere, in principle, only to the magnetized zones thereof, so that the magnetized zones which have passed in front of the application device 14 appear coated with a layer of developer, this layer forming, on the drum 10, the image of the characters which are to be printed.
  • this developer consists of magnetic particles coated with a resin which, by heating, is capable of melting and of being fixed on a paper on which it has been deposited. It should however be noted that the nature of this developer is not specific to the invention and that, in the case of an electrostatic printer to which of course the invention applies, this developer could very well consist of a known powder containing no magnetic particles. Similarly, for the application of developer on the drum 10, any conventional application device could be used.
  • the application device 14 which is shown in FIG. 1 is of the type which has been described and represented in the patent application which has been filed in France, by the Applicant , February 11, 1982 and published FR-A-2.521.069.
  • the developer adheres mainly to the magnetized zones 13, thus forming deposits 16 of particles on the surface of the drum 10.
  • These deposits 16 then pass in front of a retouching device 17 which has the role of removing the particles which have adhered elsewhere than on the magnetized areas 13, as well as the paticles which are found in excess in these areas.
  • the developer particles which remain on the drum 10 are transferred, almost entirely, onto a sheet of paper 18 which is applied to the drum 10 by means of a pressure roller 19.
  • the residual developer particles which, when this transfer is carried out, are still on the drum 10 are then removed by means of a cleaning device 20, of known type, for example with a brush. After which, the magnetized zones which have passed in front of the cleaning device 20 pass in front of an erasing device 21 where they are then erased, which allows the demagnetized portions of the drum 10 to be able to be magnetized again when they arise next before the registration body 11.
  • the retouching device 17 which has been shown in FIG. 1 comprises a suction duct 22 which, as shown in FIGS. 2 and 3, ends at each of its ends by an orifice, one of which, said to be air inlet 23, is disposed in the immediate vicinity of the surface of the drum 10, and the other of which, called the air outlet 24, communicates with a chamber 25 which will be discussed later.
  • the air inlet orifice 23 has the form of a rectangular slot which extends in a direction AA 'parallel to the axis of rotation 12 of the drum 10, the length L of this slot being substantially equal to the length of this drum.
  • the width e (FIG. 5) of this orifice 23 is always very small compared to its length L.
  • this width e is such that the ratio L is less than 0.006.
  • the distance d (FIG. 2) which separates the air inlet orifice 23 from the surface of the drum is itself very small and is at most equal to 2 mm.
  • the suction duct 22 has practically the shape of a straight prism limited on the one hand by two triangular base plates 39 and 40 arranged parallel to one another. other, on the other hand by two non-parallel walls 26 and 27 arranged perpendicular to these plates 39 and 40 converging towards the air inlet orifice 23, these non-parallel walls 26 and 27 forming between them an angle less than 30 degrees.
  • the width of the air outlet orifice 24 is always greater than that of the air inlet orifice 23.
  • the distance D which separates the two orifices 23 and 24 from the suction duct 22 is established in such a way that the width of the air outlet orifice 24 remains between 5th and 20th.
  • the width e of the inlet orifice 23 is equal to 1 millimeter
  • the width of the outlet orifice 24 is practically equal to 15 millimeters.
  • FIGS. 2 and 3 also show that the chamber 25 is in the form of a limited cylinder, on the one hand by a cylindrical wall 28, on the other hand by two opposite side walls 29 and 30.
  • the side wall 29 of the chamber and the plate 39 of the suction duct form only one piece. It is the same for the side wall 30 of the chamber and the plate 40 of the conduit.
  • the wall 29 and the plate 39 just like the wall 30 and the plate 40, could very well be made up of two different parts, fixed to each other during the assembly operation of the chamber and the conduit.
  • FIGS. 1 the embodiment illustrated by FIGS.
  • the cylinder under which the chamber is presented is a cylinder of revolution, that is to say that the line obtained by cutting this cylinder by a plane perpendicular to the generatrices of this cylinder is a circle.
  • the cylindrical chamber 25 could also be in a different cylindrical shape, that is to say such that the section of the cylinder by a plane perpendicular to the generatrices either, no longer circular, but limited by a closed non-circular curve such as, for example, an ellipse or even a curve made up of two parallel straight lines joined together, at their ends by two portions of circular line.
  • a cylindrical chamber 25, the section of which presents precisely this latter feature equips the retouching device which has been shown, by way of illustration, in FIG. 4. It should however be indicated that, as can be seen in FIGS. arrangement of the cylindrical chamber 25, with respect to the duct 22, is such that its generators are parallel to the direction of elongation AA ′ of the air inlet orifice 23.
  • Figures 3 and 4 also show that the side wall 30 of the cylindrical chamber 25 is provided with an opening 31, called the intake, of air, which opens into the open air, and that the side wall 29 of this chamber has an opening 32, called suction, provided with a tube 33 on which is normally fixed a flexible pipe 34 ensuring, as shown in Figure 1, the connection of chamber 25 to a suction source 35 of the type known.
  • the chamber 25 is provided, on its cylindrical wall 28, with a third opening 36 which corresponds with the air outlet orifice 24 of the suction duct 22 and which therefore has the same dimensions as those of this outlet orifice.
  • the dimensions of the suction opening 32 are established so that the ratio of the cross-sectional area of the suction inlet to that of the opening 32 remains between 0.3 and 0.7.
  • the dimensions of the air intake opening 31 are established so that the ratio of the cross-sectional area of the air intake orifice 23 to that of this intake opening remains between 2 and 20.
  • the suction opening 32 is circular in shape and has a diameter of 30 mm, i.e. a section practically equal to 706 mm 2 .
  • the air intake opening 31 is circular in shape and has a diameter of 15 mm, that is to say a section practically equal to 176 mm 2 .
  • the dimensions of the third cover 36, and therefore those of the outlet orifice 24 are established so that the ratio of the cross-sectional area of this third opening to that of the inlet orifice of air 23 remains between 5 and 20.
  • this third opening has a section practically equal to 6000 mm2.
  • the non-parallel walls 26 and 27 of the suction duct 22 have a relatively small thickness, generally less than 1 mm, and are shaped as shown in FIG. 2, so as to present, on either side other of the air inlet orifice 23, two end portions 37 and 38 which are mutually parallel and oriented perpendicular to the surface of the drum 10.
  • the end of these end parts 37 and 38 is bevelled at an angle ( ⁇ ) at most equal to 45 '. Under these conditions, the air flow which is produced when the suction source 35 is put into operation, follows a path which has been illustrated diagrammatically by arrows G in FIG.
  • the air flow from the suction source 35 is adjusted by known means (not shown) so that the value of the vacuum inside the suction duct 22 remains between 100 and 400 Pascals.
  • optical densities which appear in this table are those which have been measured, by means of a densitometer of the designed type, after the image of the characters formed by the deposit of developer on the drum has been transferred on paper, this paper having when virgin, an optical density practically equal to 0.05.
  • these optical density values are those which are obtained, for a drum speed of 31.4 cm / s, when a developer of the type of those used is used for the development of the latent images of this drum. which have been described in the patent application that was filed in France by the Applicant 20 March 1980 and published under No. 2,478,839.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Cleaning In Electrography (AREA)
  • Dry Development In Electrophotography (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)

Description

La présente invention se rapporte à un dispositif pour retirer les particules de révélateur en excès sur la surface d'un élément d'enregistrement. Un tel dispositif trouve plus particulièrement, quoique non exclusivement, son application dans les machines imprimantes magnétiques.The present invention relates to a device for removing excess developer particles on the surface of a recording element. Such a device finds more particularly, although not exclusively, its application in magnetic printing machines.

Dans les équipements modernes utilisés pour le traitement de l'information, on utilise de plus en plus des imprimantes rapides dans lesquelles l'impression des caractères est réalisée sans pour cela faire appel à l'impact de types d'impression en relief sur une feuille de papier réceptrice. Ces machines imprimantes, dites sans impact ou encore à transfert sans frappe, comportent généralement un élément d'enregistrement, constitué le plus souvent par un tambour rotatif ou une courroie sans fin, à la surface duquel on peut former, par voie électrostatique ou magnétique, des zones sensiblisées qui correspondent aux caractères ou images à imprimer et qui sont capables d'attirer des particules solides de révélateur. Cet élément d'enregistrement est ensuite amené au contact d'une feuille de papier réceptrice pour permettre aux particules solides qui sont retenues par les zones sensibilisées de l'élément définitivement d'être transférées sur cette feuille pour y être définitivement fixées.In modern equipment used for information processing, more and more rapid printers are used in which the printing of the characters is carried out without for this calling upon the impact of types of relief printing on a sheet. of receiving paper. These printing machines, said to be without impact or even without transfer without striking, generally comprise a recording element, most often constituted by a rotary drum or an endless belt, on the surface of which one can form, electrostatic or magnetic, sensitive zones which correspond to the characters or images to be printed and which are capable of attracting solid particles of developer. This recording element is then brought into contact with a sheet of receiving paper to allow the solid particles which are retained by the sensitized areas of the element definitively to be transferred to this sheet to be definitively fixed there.

Pour appliquer des particules solides de révélateur sur l'élément d'enregistrement d'une machine imprimante de ce type, on peut utiliser divers dispositifs d'application tels que, par exemple, celui qui a été accessoirement décrit et représenté dans le brevet des Etats Unis d'Amérique N" 3. 161. 544. Cependant, malgré tout le soin apporté à la réalisation de ces dispositifs, il est difficile d'éviter que les particules de révélateur ne se déposent, non seulement en surabondance sur les zones sensibilisées de l'élément d'enregistrement, mais aussi, même en très faible quantité, en dehors de ces zones. On attribue ce phénomène au fait que les particules, lorsqu'elles se chargent d'humidité ou d'électricité statique, ou encore lorsqu'elles subissent un ramollissement qui, même faible, les rend plus ou moins collantes, adhèrent à la surface avec laquelle elles ont été mises en contact. Le dépôt excessif de particules de révélateur sur les zones sensibilisées de l'élément d'enregistrement est indésirable parce que, lors du transfert de ce révélateur sur la feuille de papier réceptrice, le révélateur qui a éte déposé suivant la configuration de l'image formée par ces zones sensibilisées risque de s'étaler et de brouller l'image. D'autre part, le dépôt de particules de révélateur en dehors des zones sensibilisées de l'élément d'enregistrement est, lui aussi, indésirable du fait que ces particules, lorsqu'elles sont transférées sur le papier, forment un fond qui réduit le contraste entre l'image transférée et le fond original du papier.To apply solid developer particles to the recording element of a printing machine of this type, various application devices can be used such as, for example, that which has been incidentally described and represented in the patent of the States United States of America No. 3, 161. 544. However, despite all the care taken in making these devices, it is difficult to prevent developer particles from settling, not only in superabundance on the sensitized areas of the recording element, but also, even in very small quantities, outside of these zones. This phenomenon is attributed to the fact that the particles, when charged with moisture or static electricity, or even when they undergo a softening which, even weak, makes them more or less sticky, adhere to the surface with which they have been brought in. Excessive deposition of developer particles on the sensitized areas of the recording element and This is undesirable because, during the transfer of this developer onto the receiving sheet of paper, the developer which has been deposited according to the configuration of the image formed by these sensitized zones risks spreading and burning the image. On the other hand, the deposition of developer particles outside the sensitized areas of the recording element is also undesirable since these particles, when transferred to the paper, form a background which reduces the contrast between the transferred image and the original background of the paper.

Pour éliminer l'excès de révélateur sur la surface de l'élément d'enregistrement, on a utilisé dans l'art antérieur divers dispositifs. C'est ainsi qu'on connaît un dispositif de ce genre dans lequel une masse de particules de révélateur, placée en contact avec la surface de l'élément d'enregistrement et en aval du dispositif d'application des particules, décharge les particules qui adhèrent à cet élément en dehors des zones sensibilisées, si bien que ces particules déchargées se détachent de l'élément d'enregistrement et viennent s'agglomérer à cette masse. Toutefois un tel dispositif ne donne pas entière satisfaction à l'usage du fait qu'il n'assure pas toujours une décharge électrique complète des particules et qu'il ne permet pas, par conséquent, d'éliminer de façon sûre, les particules de révélateur qui subsistent sur l'élément d'enregistrement, en dehors des zones sensiblisée de celui-ci. En outre, un tel dispositif ne peut être utilisé pour retirer l'excès de particules sur l'élément d'enregistrement d'une imprimante électrostatique, car ce dispositif risquerait, en captant les charges électriques de cet élément, d'effacer les zones sensibilisées de celui-ci.To remove excess developer from the surface of the recording element, various devices have been used in the prior art. Thus, a device of this type is known in which a mass of developer particles, placed in contact with the surface of the recording element and downstream of the particle application device, discharges the particles which adhere to this element outside of the sensitized zones, so that these discharged particles detach from the recording element and come to agglomerate with this mass. However, such a device does not give complete satisfaction to the use of the fact that it does not always ensure a complete electrical discharge of the particles and that it does not therefore make it possible to safely remove the particles of developer that remain on the recording element, outside of the sensitive areas thereof. In addition, such a device cannot be used to remove excess particles on the recording element of an electrostatic printer, because this device would risk, by capturing the electric charges of this element, to erase the sensitized areas of it.

Pour remédier à ces inconvénients, on a proposé un dispositif comprenant une chambre qui, reliée à un organe pneumatique à pression, est pourvue, en regard de la surface de l'élément d'enregistrement, d'une ouverture par laquelle s'échappe l'air qui est envoyé sous pression dans la chambre, cette ouverture étant dimensionnée de manière que l'échappement de l'air s'effectue sous la forme d'un jet d'air qui vient frapper la surface et chasse ainsi les particules de révélateur en excès qui se trouvent sur cette surface. Mais ce dispositif, qui donne de bons résultats, présente cependant l'inconvénient de répandre dans l'atmosphère les particules qui ont été chassées par le jet d'air, ce qui engendre une pollution qui finit toujours par être indésirable pour les personnes se trouvant à proximité de la machine.To overcome these drawbacks, a device has been proposed comprising a chamber which, connected to a pneumatic pressure member, is provided, opposite the surface of the recording element, with an opening through which the air which is sent under pressure into the chamber, this opening being dimensioned so that the exhaust of air takes place in the form of an air jet which strikes the surface and thus expels the developer particles in excess that are on this surface. However, this device, which gives good results, however has the disadvantage of spreading into the atmosphere the particles which have been expelled by the air jet, which generates pollution which always ends up being undesirable for people in the vicinity. near the machine.

On connaît également un autre dispositif qui, fonctionnant à la manière d'un aspirateur, permet de retirer les particules de révélateur en excès, sans provoquer une pollution de l'atmosphère. Ce dernier dispositif, qui a été décrit et représenté dans la demande de brevet français publiée sous le N' 2. 322. 395, comporte, d'une part une chambre, de forme généralement cylindrique, pourvue d'une ouverture d'entrée et d'une ouverture de sortie, chacune de ces ouvertures étant située à l'une respective des deux extrémités de la chambre, l'ouverture de sortie étant reliée à une source de dépression d'air, d'autre part un conduit ou buse, de section constante, qui communique, à l'une de ses extrémités, avec l'ouverture d'entrée de la chambre, l'autre extrémité de ce conduit présentant un orifice en forme de fente disposé à une très petite distance de la surface de l'élément d'enregistrement. Dans ce dispositif l'orientation de la chambre est telle que ses génératrices sont orthogonales à la direction d'allongement de l'orifice en forme de fente du conduit. De plus, le rapport de la surface de section de l'ouverture d'entrée à celle de l'ouverture de sortie de la chambre est très petit, c'est-à-dire inférieur à 0,1, ce qui assure un débit d'air pratiquement uniforme sur toute la largeur de l'ouverture d'entrée de la chambre. On a toutefois observé que, dans ce dispositif, les particules de révélateur qui étaient aspirées, n'étaient pas toujours entraînées convenablement lors de leur passage dans la chambre, de sorte qu'une accumulation de particules finissait par apparaître sur les parois de cette chambre, provoquant, à la longue, une diminution notable du débit d'aspiration de l'appareil et, par suite, une obstruction plus ou moins importante du conduitAnother device is also known which, operating like a vacuum cleaner, makes it possible to remove excess developer particles, without causing pollution of the atmosphere. This latter device, which has been described and represented in the French patent application published under No. 2, 322,395, comprises, on the one hand, a chamber, of generally cylindrical shape, provided with an inlet opening and an outlet opening, each of these openings being located at a respective one of the two ends of the chamber, the outlet opening being connected to a source of air depression, on the other hand a duct or nozzle, of constant section, which communicates, at one of its ends, with the entry opening of the chamber, the other end of this duct having a slit-shaped orifice disposed at a very small distance from the surface of the record item. In this device, the orientation of the chamber is such that its generatrices are orthogonal to the direction of elongation of the orifice in the form of a slot in the duct. In addition, the ratio of the cross-sectional area of the inlet opening to that of the chamber outlet opening is very small, that is to say less than 0.1, which ensures a flow rate. practically uniform air across the width of the chamber entry opening. However, it has been observed that, in this device, the developer particles which were sucked in were not always properly entrained during their passage through the chamber, so that an accumulation of particles ended up appearing on the walls of this chamber. , causing, in the long run, a significant decrease in the suction flow of the device and, consequently, a more or less significant obstruction of the duct

La présente invention remédie à cet inconvénient et propose un dispositif qui permet d'aspirer, de manière efficace, les particules de révélateur en excès qui se trouvent sur la surface de l'élément d'enregistrement, sans que les particules ainsi aspirées ne s'accumulent ailleurs que sur les filtres qui ont été prévus pour les recueillir. Il en résulte que les risques d'encrassement de ce dispositif sont pratiquement éliminés, ce qui permet à ce dispositif de fonctionner dans des conditions optimales qui, au cours du temps, ne subissent aucune modification.The present invention overcomes this drawback and proposes a device which makes it possible to efficiently suck up the excess developer particles which are on the surface of the recording element, without the particles thus sucked up accumulate elsewhere than on the filters that have been designed to collect them. As a result, the risks of fouling of this device are practically eliminated, which allows this device to operate under optimal conditions which, over time, do not undergo any modification.

Plus précisément, la présente invention concerne un dispositif pour retirer d'une surface sur laquelle un révélateur pulvérulent a été déposé, les particules de révélateur en excès qui adhèrent à cette surface, ce dispositif comprenant un conduit d'aspiration présentant un orifice à chacune de ses deux extrémités, l'un de ces orifices, dit d'entrée d'air, ayant la forme d'une fente et s'étendant parallèlement à ladite surface, à proximité immédiate de celle-ci, tandis que l'autre orifice, dit de sortie d'air, est relié à une source d'aspiration par l'intermédiaire d'une chambre cylindrique solidaire dudit conduit d'aspiration, ledit dispositif étant caractérisé en ce que ladite chambre est disposée de telle manière que ses génératrices sont parallèles à la direction d'allongement de l'orifice d'entrée d'air du conduit, et en ce que les deux parties latérales opposées de ladite chambre sont pourvues chacune d'une ouverture dont l'une, dite d'admission d'air, débouche à l'air libre, tandis que l'autre, dite d'aspiration, communique avec ladite source d'aspiration, ladite chambre étant pourvue en outre, sur sa paroi cylindrique, d'une troisième ouverture qui correspond avec l'orifice de sortie d'air dudit conduit, le rapport de la surface de section dudit orifice d'entrée d'air à celle de ladite ouverture d'aspiration étant compris entre 0,3 et 0,7, et le rapport de la surface de section dudit orifice d'entrée d'air à celle àe ladite ouverture d'admission d'air étant compris entre 2 et 20.More specifically, the present invention relates to a device for removing from a surface on which a powder developer has been deposited, the excess developer particles which adhere to this surface, this device comprising a suction duct having an orifice at each of its two ends, one of these orifices, called the air inlet, having the form of a slit and extending parallel to said surface, in the immediate vicinity thereof, while the other orifice, said air outlet, is connected to a suction source by means of a cylindrical chamber integral with said suction duct, said device being characterized in that said chamber is arranged in such a way that its generators are parallel in the direction of elongation of the air inlet orifice of the duct, and in that the two opposite lateral parts of said chamber are each provided with an opening, one of which, called the air intake , leads to the open air, tand is that the other, called suction, communicates with said suction source, said chamber being further provided, on its cylindrical wall, with a third opening which corresponds with the air outlet orifice of said duct, the ratio of the cross-sectional area of said air inlet to that of said suction opening being between 0.3 and 0.7, and the cross-sectional area of said air inlet to that of said air intake opening being between 2 and 20.

L'invention sera mieux comprise et d'autres buts, détails et avantages de celle-ci apparaîtront mieux dans la description suivante, donnée à titre d'exemple non limitatif et en se référant aux dessins annexés sur lesquels:

  • La figure 1: représente une vue schématique partielle d'une machine imprimante munie d'un dispositif établi selon l'invention;
  • La figure 2: est une vue en coupe, montrant la structure interne du dispositif de l'invention faisant partie de la machine représentée sur la figure 1;
  • La figure 3: est une vue agrandie, en perspective, du dispositif de l'invention, cette vue étant destinée à montrer la disposition des principaux éléments constitufs de la chambre qui fait partie de ce dispositif;
  • La figure 4: représente une variante de réalisation du dispositif de la figure 3;
  • La figure 5: represente une vue de détail, en coupe, du dispositif de la figure 2;
  • La figure 6: est une photo montrant l'aspect présenté par un caractère imprimé par la machine, lorsque le dispositif de l'invention ne fonctionne pas, et
  • La figure 7: est une photo montrant l'aspect présenté par ce même caractère lorsque le dispositif de l'invention est en fonctionnement.
The invention will be better understood and other objects, details and advantages thereof will appear better in the following description, given by way of nonlimiting example and with reference to the appended drawings in which:
  • Figure 1: shows a partial schematic view of a printing machine provided with a device established according to the invention;
  • Figure 2: is a sectional view showing the internal structure of the device of the invention forming part of the machine shown in Figure 1;
  • Figure 3: is an enlarged perspective view of the device of the invention, this view being intended to show the arrangement of the main components of the room which is part of this device;
  • Figure 4: shows an alternative embodiment of the device of Figure 3;
  • Figure 5: shows a detail view, in section, of the device of Figure 2;
  • FIG. 6: is a photo showing the appearance presented by a character printed by the machine, when the device of the invention does not work, and
  • FIG. 7: is a photo showing the appearance presented by this same character when the device of the invention is in operation.

La machine imprimante dont une partie a été schématiquement représentée sur la figure 1 comprend un élément d'enregistrement qui est constitué, dans l'exemple décrit, par un tambour magnétique 10. Ce tambour magnétique 10 est entraîné en rotation, dans le sens de la flèche F, par un moteur électrique (non représenté). L'enregistrement des informations sur ce tambour est réalisé par un organe d'enregistrement magnétique 11 qui est disposé à proximité de la surface externe du tambour. Dans l'exemple décrit, cet organe d'enregistrement 11 est formé d'un ensemble comprenant plusieurs têtes d'enregistrement magnétique qui, placées les unes à côté des autres, sont alignées parallèlement à l'axe de rotation 12 du tambour 10. Chacune de ces têtes engendre, lorsqu'elle est exitée à différentes reprises par un courant électrique, un champ magnétique variable, ce qui a pour effet de créer des domaines magnétisés ou «points magnétiques», sur la surface du tambour qui défile devant l'organe d'enregistrement 11. Les instants d'excitations de ces têtes sont d'ailleurs établis, de manière connue, de façon à obtenir sur la surface du tambour des ensembles de domaines magnétisés 13, appelés zones magnétisées ou images magnétiques latentes, dont la forme correspond à celle des caractères à imprimer. Ces zones magnétisées 13 passent ensuite devant un dispositif d'application 14 qui est disposé au-dessous du tambour 10 et qui permet d'appliquer sur la surface du tambour des particules d'un révélateur pulvérulent contenu dans un réservoir 15. Les particules de révélateur qui sont ainsi appliquées sur le tambour 10 n'adhèrent, en principe, que sur les zones magnétisées de celui-ci, de sorte que les zones magnétisées qui sont passées devant le dispositif d'application 14 apparaissent revêtues d'une couche de révélateur, cette couche formant, sur le tambour 10, l'image des caractères qui doivent être imprimés. Dans l'exemple décrit, ce révélateur est constitué de particules magnétiques enduites d'une résine qui, par chauffage, est capable de fondre et de se fixer sur un papier sur lequel elle a été déposée. Il faut cependant signaler que la nature de ce révélateur n'est pas spécifique de l'invention et que, dans le cas d'une imprimante électrostatique à laquelle bien entendu s'applique l'invention, ce révélateur pourrait très bien être constitué d'une poudre connue ne comportant aucune particule magnétique. De même, pour l'application de révélateur sur le tambour 10, on pourrait utiliser n'importe quel dispositif d'application classique. Cependant, dans un mode de réalisation plus particulièrement avantageux, le dispositif d'application 14 qui est montré sur la figure 1 est du type de celui qui a été décrit et représenté dans la demande de brevet qui a été déposée en France, par la Demanderesse, le 11 Février 1982 et publiée FR-A-2.521.069. Le révélateur adhère principalement sur les zones magnétisées 13, formant ainsi des dépôts 16 de particules à la surface du tambour 10. Ces dépôts 16 passent alors devant un dispositif de retouche 17 qui a pour rôle d'éliminer les particules ayant adhéré ailleurs que sur les zones magnétisées 13, ainsi que les paticules qui se trouvent en surnombre sur ces zones. Après quoi, les particules de révélateur qui subsistent sur le tambour 10 sont transférées, en quasi totalité, sur une feuille de papier 18 qui est appliquée sur le tambour 10 grâce à un rouleau de pression 19. Les particules résiduelles de révélateur qui, lorsque ce transfert est réalisé, se trouvent encore sur le tambour 10 sont alors enlevées au moyen d'un dispositif de nettoyage 20, de type connu, par exemple à brosse. Après quoi, les zones magnétisées qui sont passées devant le dispositif de nettoyage 20 défilent devant un dispositif d'effacement 21 où elles sont alors effacées, ce qui permet aux portions démagnétisées du tambour 10 de pouvoir être à nouveau magnétisées lorsqu'elles se présentent ensuite devant l'organe d'enregistrement 11.The printing machine, part of which has been shown diagrammatically in FIG. 1, comprises a recording element which is constituted, in the example described, by a magnetic drum 10. This magnetic drum 10 is driven in rotation, in the direction of the arrow F, by an electric motor (not shown). The recording of information on this drum is carried out by a magnetic recording member 11 which is arranged near the external surface of the drum. In the example described, this recording member 11 is formed of an assembly comprising several magnetic recording heads which, placed one next to the other, are aligned parallel to the axis of rotation 12 of the drum 10. Each of these heads generates, when it is repeatedly exited by an electric current, a variable magnetic field, which has the effect of creating magnetized domains or "magnetic points", on the surface of the drum which passes in front of the organ 11. The instants of excitation of these heads are moreover established, in a known manner, so as to obtain on the surface of the drum sets of magnetized domains 13, called magnetized zones or latent magnetic images, the shape of which corresponds to that of the characters to be printed. These magnetized zones 13 then pass in front of an application device 14 which is arranged below the drum 10 and which makes it possible to apply to the surface of the drum particles of a powdery developer contained in a reservoir 15. The developer particles which are thus applied to the drum 10 adhere, in principle, only to the magnetized zones thereof, so that the magnetized zones which have passed in front of the application device 14 appear coated with a layer of developer, this layer forming, on the drum 10, the image of the characters which are to be printed. In the example described, this developer consists of magnetic particles coated with a resin which, by heating, is capable of melting and of being fixed on a paper on which it has been deposited. It should however be noted that the nature of this developer is not specific to the invention and that, in the case of an electrostatic printer to which of course the invention applies, this developer could very well consist of a known powder containing no magnetic particles. Similarly, for the application of developer on the drum 10, any conventional application device could be used. However, in a more particularly advantageous embodiment, the application device 14 which is shown in FIG. 1 is of the type which has been described and represented in the patent application which has been filed in France, by the Applicant , February 11, 1982 and published FR-A-2.521.069. The developer adheres mainly to the magnetized zones 13, thus forming deposits 16 of particles on the surface of the drum 10. These deposits 16 then pass in front of a retouching device 17 which has the role of removing the particles which have adhered elsewhere than on the magnetized areas 13, as well as the paticles which are found in excess in these areas. After which, the developer particles which remain on the drum 10 are transferred, almost entirely, onto a sheet of paper 18 which is applied to the drum 10 by means of a pressure roller 19. The residual developer particles which, when this transfer is carried out, are still on the drum 10 are then removed by means of a cleaning device 20, of known type, for example with a brush. After which, the magnetized zones which have passed in front of the cleaning device 20 pass in front of an erasing device 21 where they are then erased, which allows the demagnetized portions of the drum 10 to be able to be magnetized again when they arise next before the registration body 11.

Le dispositif de retouche 17 qui a été représenté sur la figure 1 comprend un conduit d'aspiration 22 qui, comme le montrent les figures 2 et 3, se termine, à chacune de ses extrémités par un orifice dont l'un, dit d'entrée d'air 23, est disposé à proximité immédiate de la surface du tambour 10, et dont l'autre, dit de sortie d'air 24, communique avec une chambre 25 dont il sera question plus loin. L'orifice d'entrée d'air 23 a la forme d'une fente rectangulaire qui s'etend suivant une direction AA' parallèle à l'axe de rotation 12 du tambour 10, la longueur L de cette fente étant sensiblement égale à la longueur de ce tambour. La largeur e (figure 5) de cet orifice 23 est toujours très petite par rapport à sa longueur L. Plus précisément, cette largeur e est telle que le rapporte L est inférieur à 0,006. La distance d (figure 2) qui sépare l'orifice d'entrée d'air 23 de la surface du tambour est elle-même très faible et est au plus égale à 2 mm. Ainsi qu'on peut le voir sur les figures 2 et 3, le conduit d'aspiration 22 a pratiquement la forme d'un prisme droit limité d'une part par deux plaques de base triangulaires 39 et 40 disposées parallèlement l'une à l'autre, d'autre part par deux parois non parallèles 26 et 27 disposées perpendiculairement à ces plaques 39 et 40 convergeant vers l'orifice d'entrée d'air 23, ces parois non parallèles 26 et 27 formant entre elles un angle inférieur à 30 degrés. Dans ces conditions, la largeur de l'orifice de sortie d'air 24 est toujours supérieure à celle de l'orifice d'entrée d'air 23. La distance D qui sépare les deux orifices 23 et 24 du conduit d'aspiration 22 est établie de telle manière que la largeur de l'orifice de sortie d'air 24 reste comprise entre 5e et 20e. C'est ainsi que, dans l'exemple décrit où la largeur e de l'orifice d'entrée 23 est égale à 1 millimètre, la largeur de l'orifice de sortie 24 est pratiquement égale à 15 millimètres.The retouching device 17 which has been shown in FIG. 1 comprises a suction duct 22 which, as shown in FIGS. 2 and 3, ends at each of its ends by an orifice, one of which, said to be air inlet 23, is disposed in the immediate vicinity of the surface of the drum 10, and the other of which, called the air outlet 24, communicates with a chamber 25 which will be discussed later. The air inlet orifice 23 has the form of a rectangular slot which extends in a direction AA 'parallel to the axis of rotation 12 of the drum 10, the length L of this slot being substantially equal to the length of this drum. The width e (FIG. 5) of this orifice 23 is always very small compared to its length L. More precisely, this width e is such that the ratio L is less than 0.006. The distance d (FIG. 2) which separates the air inlet orifice 23 from the surface of the drum is itself very small and is at most equal to 2 mm. As can be seen in FIGS. 2 and 3, the suction duct 22 has practically the shape of a straight prism limited on the one hand by two triangular base plates 39 and 40 arranged parallel to one another. other, on the other hand by two non-parallel walls 26 and 27 arranged perpendicular to these plates 39 and 40 converging towards the air inlet orifice 23, these non-parallel walls 26 and 27 forming between them an angle less than 30 degrees. Under these conditions, the width of the air outlet orifice 24 is always greater than that of the air inlet orifice 23. The distance D which separates the two orifices 23 and 24 from the suction duct 22 is established in such a way that the width of the air outlet orifice 24 remains between 5th and 20th. Thus, in the example described where the width e of the inlet orifice 23 is equal to 1 millimeter, the width of the outlet orifice 24 is practically equal to 15 millimeters.

Les figures 2 et 3 montrent encore que la chambre 25 se présente sous la forme d'un cylindre limité, d'une part par une paroi cylindrique 28, d'autre part par deux parois latérales opposées 29 et 30. Sur les figures 2 et 3 on peut remarquer que la paroi latérale 29 de la chambre et la plaque 39 du conduit d'aspiration ne forment qu'une seule pièce. Il en est de même de la paroi latérale 30 de la chambre et de la plaque 40 du conduit. Toutefois, dans le cas où la chambre 25 et le conduit d'aspiration 22 seraient fabriqués séparément, puis assemblés entre eux de manière connue, par exemple par soudage, la paroi 29 et la plaque 39, tout comme d'ailleurs la paroi 30 et la plaque 40, pourraient très bien être consitutées de deux pièces différentes, fixées l'une à l'autre lors de l'opération d'assemblage de la chambre et du conduit. Dans l'exemple de réalisation illustré par les figures 1 à 3, le cylindre sous lequel se présente la chambre est un cylindre de révolution, c'est-à-dire que la ligne obtenue en coupant ce cylindre par un plan perpendiculaire aux génératrices de ce cylindre est un cercle. Il faut toutefois signaler que cette disposition n'est pas spécifique de l'invention et que la chambre cylindrique 25 pourrait également se présenter sous une forme cylindrique différente, c'est-à-dire telle que la section du cylindre par un plan perpendiculaire aux génératrices soit, non plus circulaire, mais limitée par une courbe fermée non circulaire telle que, par exemple, une ellipse ou encore une courbe constituée de deux segments de droite parallèles réunis, à leurs extrémités par deux portions de ligne circulaire. Une chambre cylindrique 25 dont la section présente précisément cette dernière particularité équipe le dispositif de retouche qui a été représenté, à titre illustratif, sur la figure 4. Il faut cependant indiquer que, comme on peut le voir sur les figures 3 et 4, la disposition de la chambre cylindrique 25, par rapport au conduit 22, est telle que ses géneratrices sont parallèles à la direction d'allongement AA' de l'orifice d'entrée d'air 23.FIGS. 2 and 3 also show that the chamber 25 is in the form of a limited cylinder, on the one hand by a cylindrical wall 28, on the other hand by two opposite side walls 29 and 30. In FIGS. 2 and 3 it can be noted that the side wall 29 of the chamber and the plate 39 of the suction duct form only one piece. It is the same for the side wall 30 of the chamber and the plate 40 of the conduit. However, in the case where the chamber 25 and the suction duct 22 are manufactured separately, then assembled together in a known manner, for example by welding, the wall 29 and the plate 39, just like the wall 30 and the plate 40, could very well be made up of two different parts, fixed to each other during the assembly operation of the chamber and the conduit. In the embodiment illustrated by FIGS. 1 to 3, the cylinder under which the chamber is presented is a cylinder of revolution, that is to say that the line obtained by cutting this cylinder by a plane perpendicular to the generatrices of this cylinder is a circle. However, it should be noted that this arrangement is not specific to the invention and that the cylindrical chamber 25 could also be in a different cylindrical shape, that is to say such that the section of the cylinder by a plane perpendicular to the generatrices either, no longer circular, but limited by a closed non-circular curve such as, for example, an ellipse or even a curve made up of two parallel straight lines joined together, at their ends by two portions of circular line. A cylindrical chamber 25, the section of which presents precisely this latter feature equips the retouching device which has been shown, by way of illustration, in FIG. 4. It should however be indicated that, as can be seen in FIGS. arrangement of the cylindrical chamber 25, with respect to the duct 22, is such that its generators are parallel to the direction of elongation AA ′ of the air inlet orifice 23.

Les figures 3 et 4 montrent encore que la paroi latérale 30 de la chambre cylindrique 25 est pourvue d'une ouverture 31, dite d'admission, d'air, qui débouche à l'air libre, et que la paroi latérale 29 de cette chambre présente une ouverture 32, dite d'aspiration, munie d'une tubulure 33 sur laquelle est normalement fixée une canalisation flexible 34 assurant, comme le montre la figure 1, le raccordement de la chambre 25 à une source d'aspiration 35 de type connu. D'autre part, ainsi qu'on peut le voir sur les figures 2, 3 et 4, la chambre 25 est pourvue, sur sa paroi cylindrique 28, d'une troisième ouverture 36 qui correspond avec l'orifice de sortie d'air 24 du conduit d'aspiration 22 et qui a, par conséquent, les mêmes dimensions que celles de cet orifice de sortie.Figures 3 and 4 also show that the side wall 30 of the cylindrical chamber 25 is provided with an opening 31, called the intake, of air, which opens into the open air, and that the side wall 29 of this chamber has an opening 32, called suction, provided with a tube 33 on which is normally fixed a flexible pipe 34 ensuring, as shown in Figure 1, the connection of chamber 25 to a suction source 35 of the type known. On the other hand, as can be seen in Figures 2, 3 and 4, the chamber 25 is provided, on its cylindrical wall 28, with a third opening 36 which corresponds with the air outlet orifice 24 of the suction duct 22 and which therefore has the same dimensions as those of this outlet orifice.

Les dimensions de l'ouverture d'aspiration 32 sont établies de manière que le rapport de la surface de section de l'orifice d'entrée d'aspiration à celle de l'ouverture 32 reste compris entre 0,3 et 0,7. De même, les dimensions de l'ouverture d'admission d'air 31 sont établies de manière que le rapport de la surface de section de l'orifice d'entrée d'air 23 à celle de cette ouverture d'admission reste compris entre 2 et 20. C'est ainsi que, dans l'exemple de réalisation illustré par la figure 3, où la section de l'orifice d'entrée d'air 23 est égale à 400 mm2, l'ouverture d'aspiration 32 est de forme circulaire et a un diamètre de 30 mm, c'est-à-dire une section pratiquement égale à 706 mm2. De même, dans l'exemple considéré, l'ouverture d'admission d'air 31 est de forme circulaire et a un diamètre de 15 mm, c'est-à-dire une section pratiquement égale à 176 mm2. Par ailleurs, les dimensions de la troisième cuverture 36, et par conséquent, celles de l'orifice de sortie 24 sont établies de manière que le rapport de la surface de section de cette troisième ouverture à celle de l'orifice d'entrée d'air 23 reste compris entre 5 et 20. C'est ainsi que, dans l'exemple considéré ci-dessus, cette troisième ouverture a une section pratiquement égale à 6000 mm2. The dimensions of the suction opening 32 are established so that the ratio of the cross-sectional area of the suction inlet to that of the opening 32 remains between 0.3 and 0.7. Likewise, the dimensions of the air intake opening 31 are established so that the ratio of the cross-sectional area of the air intake orifice 23 to that of this intake opening remains between 2 and 20. Thus, in the embodiment illustrated in FIG. 3, where the section of the air inlet orifice 23 is equal to 400 mm 2 , the suction opening 32 is circular in shape and has a diameter of 30 mm, i.e. a section practically equal to 706 mm 2 . Likewise, in the example considered, the air intake opening 31 is circular in shape and has a diameter of 15 mm, that is to say a section practically equal to 176 mm 2 . Furthermore, the dimensions of the third cover 36, and therefore those of the outlet orifice 24 are established so that the ratio of the cross-sectional area of this third opening to that of the inlet orifice of air 23 remains between 5 and 20. Thus, in the example considered above, this third opening has a section practically equal to 6000 mm2.

Il faut encore signaler que les parois non parallèles 26 et 27 du conduit d'aspiration 22 ont une épaisseur relativement faible, généralement inférieure à 1 mm, et sont conformées comme le montre la figure 2, de manière à présenter, de part et d'autre de l'orifice d'entrée d'air 23, deux parties terminales 37 et 38 qui sont parallèles entre elles et orientées perpendiculairement à la surface du tambour 10. En outre, dans un mode préférentiel de réalisation qui a été illustré sur la figure 5, l'extrémité des ces parties terminales 37 et 38 est biseautée suivant un angle (α) au plus égal à 45'. Dans ces conditions, le flux d'air qui est produit lorsque la source d'aspiration 35 est mise en fonctionnement, suit un trajet qui a été illustré schématiquement par des flèches G sur la figure 5, et qui est tel que la longueur P, considérée dans une direction parallèle au sens de défiliement du tambour 10, de la surface de ce tambour qui est soumise à l'action de ce flux d'air est relativement réduite et n'excède pas pratiquement trois fois la largeur e de l'orifice d'entrée d'air 23. Il en résulte alors que ce flux d'air travaille à la manière d'une lame d'air orientée perpendiculairement à la surface du tambour, si bien que son action diffère totalement de celle du flux d'air du dispositif décrit FR-A-2.322.395, dans lequel le flux d'air travaille par cisaillement, c'est-à-dire parallèlement à la surface du tambour sur une longueur au moins égale à six fois la largeur de l'orifice d'entrée d'air. Il faut encore signaler que le débit d'air de la source d'aspiration 35 est ajusté par des moyens connus (non représentés) de manière que la valeur de la dépression à l'intérieur du conduit d'aspiration 22 reste comprise entre 100 et 400 Pascals. En opérant dans ces conditions, on a observé qui'il ne se produisait aucun dépôt de particules de révélateur à l'intérieur du dispositif qui vient d'être décrit, et que toutes les particules recueillies par ce dispositif venaient s'accumuler sur les filtres prévus à cet effet, en aval de la chambre 25. On a également constaté que ce dispositif assurait une élimination pratiquement totale des particules de révélateur sur les zones de fond du tambour 10, sans pour cela réduire notablement l'opacité des caractères formés par le dépôt du révélateur sur les zones magnétisées de ce tambour. Ces résultats sont illustrés par les valeurs figurant dans le tableau ci-dessous qui donne les valeurs relevées de la densité optique du fond et de la densité optique au sein de chaque caractère, en fonction de la valeur de la dépression p à l'intérieur du conduit d'aspiration, cette dépression représentant l'écart entre la valeur de la pression atmosphérique et la valeur de la pression (inférieure à celle de la pression atmosphérique) qui s'établit à l'intérieur du conduit 22 lorsque la source d'aspiration 35 est mise en fonctionnement.It should also be noted that the non-parallel walls 26 and 27 of the suction duct 22 have a relatively small thickness, generally less than 1 mm, and are shaped as shown in FIG. 2, so as to present, on either side other of the air inlet orifice 23, two end portions 37 and 38 which are mutually parallel and oriented perpendicular to the surface of the drum 10. In addition, in a preferred embodiment which has been illustrated in the figure 5, the end of these end parts 37 and 38 is bevelled at an angle (α) at most equal to 45 '. Under these conditions, the air flow which is produced when the suction source 35 is put into operation, follows a path which has been illustrated diagrammatically by arrows G in FIG. 5, and which is such that the length P, considered in a direction parallel to the direction of movement of the drum 10, the surface of this drum which is subjected to the action of this air flow is relatively reduced and does not exceed practically three times the width e of the orifice air inlet 23. This then results in this air flow working in the manner of an air knife oriented perpendicular to the surface of the drum, so that its action differs completely from that of the air flow. air of the device described FR-A-2,322,395, in which the air flow works by shearing, that is to say parallel to the surface of the drum over a length at least equal to six times the width of the air inlet port. It should also be noted that the air flow from the suction source 35 is adjusted by known means (not shown) so that the value of the vacuum inside the suction duct 22 remains between 100 and 400 Pascals. By operating under these conditions, it has been observed that no deposit of developer particles occurs inside the device which has just been described, and that all the particles collected by this device come to accumulate on the filters. provided for this purpose, downstream of the chamber 25. It has also been found that this device ensures practically total elimination of the developer particles on the bottom zones of the drum 10, without for this significantly reducing the opacity of the characters formed by the depositing the developer on the magnetized areas of this drum. These results are illustrated by the values appearing in the table below which gives the values recorded for the optical density of the background and of the optical density within each character, as a function of the value of the depression p inside the suction duct, this depression representing the difference between the value of atmospheric pressure and the value of pressure (lower than that of atmospheric pressure) which is established inside the duct 22 when the suction source 35 is put into operation.

Il convient de signaler ici que les densités optiques qui figurent dans ce tableau sont celles qui ont été mesurées, au moyen d'un densitomètre de type conu, après que l'image des caractères formée par le dépôt de révélateur sur le tambour ait été transférée sur le papier, ce papier présentant lorsqu'il est vierge, une densité optique pratiquement égale à 0,05. En outre, ces valeurs de densités optiques sont celles que l'on obtient, pour une vitesse du tambour de 31,4 cm/s, lorsqu'on utilise, pour le développement des images latentes de ce tambour, un révélateur du type de ceux qui ont éte décrits dans la demande de brevet qui a été déposée en France par la Demanderesse le 20 Mars 1980 et publiée sous le N* 2.478.839. On voit ainsi, d'après les valeurs qui figurent dans le tableau ci-dessus, que pour des valeurs de dépression comprises entre 100 et 400 Pascals, la densité optique du fond est voisine de celle que présente le papier lorsqu'il est vierge. En particulier, pour les valeurs de dépression voisines de 400 Pascals, on obtient une élimination pratiquement totale du révélateur sur les zones de fond du papier. On voit, par ailleurs que, pour les valeurs de dépression comprises entre 100 et 400 Pascals, la densité optique au sein de chaque caractère varie très peu, de sorte que les variations observées dans l'opacité de chaque caractère sont pratiquement négligeables. Il faut encore signaler que le dispositif de l'invention, lorsqu'il est utilisé dans les conditions qui viennent d'être décrites, améliore considérablement la netteté des caractères ainsi qu'on peut le voir sur les photos des figures 6 et 7, la photo de la figure 6 montrant l'aspect, à grande échelle, présenté par un caractère lorsque le dispositif de l'invention n'est pas mis en action, la photo de la figure 7 montrant l'aspect que présente ce même caractère lorsque ce dispositif est utilisé dans les conditions décrites plus haut. Bien entendu, l'invention n'est nullement limitée aux modes de mise en oeuvre décrits et illustrés qui n'ont été donnés qu'à titre d'exemple. Au contraire, elle comrpend tous les moyens constituant des équivalents techniques de ceux décrits et illustrés, considérés isolément ou en combinaison et mis en oeuvre dans le cadre des revendications qui suivent.

Figure imgb0001
It should be noted here that the optical densities which appear in this table are those which have been measured, by means of a densitometer of the designed type, after the image of the characters formed by the deposit of developer on the drum has been transferred on paper, this paper having when virgin, an optical density practically equal to 0.05. In addition, these optical density values are those which are obtained, for a drum speed of 31.4 cm / s, when a developer of the type of those used is used for the development of the latent images of this drum. which have been described in the patent application that was filed in France by the Applicant 20 March 1980 and published under No. 2,478,839. It is thus seen, according to the values which appear in the table above, that for values of depression ranging between 100 and 400 Pascals, the optical density of the bottom is close to that which the paper presents when it is virgin. In particular, for the depression values close to 400 Pascals, an almost total elimination of the developer is obtained on the bottom areas of the paper. It can also be seen that, for the depression values between 100 and 400 Pascals, the optical density within each character varies very little, so that the variations observed in the opacity of each character are practically negligible. It should also be noted that the device of the invention, when used under the conditions which have just been described, considerably improves the sharpness of the characters as can be seen in the photos of FIGS. 6 and 7, the photo of FIG. 6 showing the appearance, on a large scale, presented by a character when the device of the invention is not put into action, the photo of FIG. 7 showing the appearance that this same character has when this device is used under the conditions described above. Of course, the invention is in no way limited to the embodiments described and illustrated which have been given only by way of example. On the contrary, it includes all the means constituting technical equivalents of those described and illustrated, considered in isolation or in combination and used in the context of the claims which follow.
Figure imgb0001

Claims (8)

1. A device for removal from a surface on which a pulverulent developer (toner) has been deposited, of the surplus developer particles adhering to this surface, said device comprising a suction duct (22) having an apertre at each of its two extremities, one of these apertures, referred to as air inlet (23), having the form of a slot and extending parallel to the said surface in immediate proximity to the same, whereas te other aperture, referred to as air outlet (24), is connected to a vacuum source (35) via a cylindrical chamber (25) integral with the said suction duct, the said device being characterised in that the said chamber (25) is arranged in such a manner that its generatrixes are parallel to the direction of elongation (AA') of the air inlet opening (23) of the duct (22), and in that the two opposed sidewalls (29 and 30) of the said chamber (25) are each provided with an opening, of which the one, referred to as an air inlet (31), opens into ambient air, whereas the other, referred to as suction opening (32), is in communication with the said vacuum source (35), the said chamber (25) furthermore being provided in its cylindrical wall (28) with a third opening (36) which corresponds to the air outlet orifice (24) of the said air inlet orifice (23) and that of the said suction opening (32) being comprised between 0.3 and 0.7, and the ratio between the cross-sectional area of the said air inlet orifice (23) and that of the said air inlet opening (31) being comprised between 2 and 20.
2. A device according to claim 1, characterised in that the chamber (25) has the shape of a cylinder of revolution.
3. A device according to one of claims 1 and 2, characterised in that the distance separating the air inlet orifice (23) from the surface is at the most equal to two millimetres.
4. A device according to any one of claims 1 to 3, characterised in that the air inlet orifice (23) has the shape of a rectangular slot, the ratio between the width (e) and the length (L) of this slot being smaller than 0.006.
5. A device according to claim 4, characterised in that the suction duct (22) practically has the form of a right prism delimited on the one hand by two triangular base plates (39,40) positioned mutually parallel, and on the other hand by two non-parallel walls (26,27) disposed perpendicular to these plates and converging towards the air inlet orifice (23), these non-parallel walls forming between them an angle smaller than 30 degrees.
6. A device according to claim 5, characterised in that the width of the air outlet orifice (24) is comprised between 5e and 20e, e being the width of the air inlet orifice (23).
7. A device according to any one of claims 1 to 4, characterised in that the flow of the suction source (35) is adjusted in such manner that the value of the negative pressure within the suction duct (22) remains comprised between 100 and 400 Pascals.
8. A device according to claim 5, characterised in that the non-parallel walls (26,27) comprise two terminal portions (37,38) of which the extremity is chamfered at an angle of at most 45°.
EP83400999A 1982-07-22 1983-05-19 Device for removing excessive developer material from the surface of a recording member Expired EP0100246B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8212831 1982-07-22
FR8212831A FR2530837B1 (en) 1982-07-22 1982-07-22 DEVICE FOR REMOVING EXCESSIVE DEVELOPER PARTICLES FROM THE SURFACE OF A RECORDING ELEMENT

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EP0100246A1 EP0100246A1 (en) 1984-02-08
EP0100246B1 true EP0100246B1 (en) 1986-07-23

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EP (1) EP0100246B1 (en)
JP (1) JPS5919980A (en)
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Publication number Priority date Publication date Assignee Title
US4666282A (en) * 1986-03-03 1987-05-19 Xerox Corporation Contamination control for xerographic developing systems
JPS6334571A (en) * 1986-07-30 1988-02-15 Fuji Xerox Co Ltd Copying method
JPS6324567U (en) * 1986-07-30 1988-02-18
JPS6334572A (en) * 1986-07-30 1988-02-15 Fuji Xerox Co Ltd Intermediate transfer method
US4797708A (en) * 1987-05-04 1989-01-10 Eastman Kodak Company Apparatus for scavenging unwanted particles from a photoconductor of an electrographic apparatus
US4903084A (en) * 1987-12-14 1990-02-20 Eastman Kodak Company Cleaning apparatus having an interference-fit housing
JP2526614Y2 (en) * 1990-04-10 1997-02-19 旭光学工業株式会社 Structure for preventing contamination in an image forming apparatus using electrophotography.
US5268727A (en) * 1992-11-13 1993-12-07 Xerox Corporation Uniform velocity air manifold

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3161544A (en) * 1960-06-14 1964-12-15 Gen Electric Recording and portraying apparatus
JPS5038940B2 (en) * 1972-08-31 1975-12-13
JPS5734511Y2 (en) * 1974-05-14 1982-07-30
US4014065A (en) * 1975-08-27 1977-03-29 Xerox Corporation Magnetic developer removal system
US4271559A (en) * 1978-05-08 1981-06-09 Gould Inc. Toner clean-off head
US4233382A (en) * 1978-10-27 1980-11-11 E. I. Du Pont De Nemours And Company Electrostatic transfer of magnetically held toner images
JPS55113061A (en) * 1979-02-24 1980-09-01 Konishiroku Photo Ind Co Ltd Scattering toner collector
JPS55138660U (en) * 1979-03-26 1980-10-02
US4304026A (en) * 1979-10-01 1981-12-08 Xerox Corporation Cleaning apparatus for a xerographic reproduction machine
JPS5792354A (en) * 1980-11-28 1982-06-08 Canon Inc Dust collection device

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JPH0477311B2 (en) 1992-12-08
EP0100246A1 (en) 1984-02-08
DE3364698D1 (en) 1986-08-28
FR2530837A1 (en) 1984-01-27
JPS5919980A (en) 1984-02-01
US4538321A (en) 1985-09-03
FR2530837B1 (en) 1986-08-14

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