EP0221452B1 - Electrostatic-image print head - Google Patents
Electrostatic-image print head Download PDFInfo
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- EP0221452B1 EP0221452B1 EP86114690A EP86114690A EP0221452B1 EP 0221452 B1 EP0221452 B1 EP 0221452B1 EP 86114690 A EP86114690 A EP 86114690A EP 86114690 A EP86114690 A EP 86114690A EP 0221452 B1 EP0221452 B1 EP 0221452B1
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- electrodes
- counterelectrodes
- recording medium
- counter
- coupling electrode
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/385—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material
- B41J2/39—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material using multi-stylus heads
- B41J2/395—Structure of multi-stylus heads
Definitions
- the present invention relates to an electrostatic image printing head.
- Such electrostatic printheads make it possible to gradually create a latent electrostatic image on a moving dielectric recording medium by means of ionic discharges.
- direct electrostatic printing requires a special paper consisting of a conductive base covered by a thin dielectric film.
- a latent electrostatic image is created on the special paper by ionic discharge in the air by means of a row of small electrodes brought to high voltage.
- the latent image is inked, for example using a magnetic brush carrying powdered ink, then fixed on the special paper by pressure and / or by cooking.
- a high voltage is created between at least one of the electrodes and at least one counter-electrode placed nearby so that the resulting electric field at the electrode is perpendicular to the surface of the special paper.
- the counter-electrodes are placed on the same side of the special paper as the electrodes and the discharge takes place by the capacitive effect of the counter-electrodes through the dielectric film with which the special paper is provided and due to conduction of the conductive base of this special paper.
- the individual electrodes used in the print head are of very small dimensions and in large number, for an image line of given length, so as to allow for example the printing of eight dots per millimeter.
- the high voltage necessary for ionic discharges is preferably shared between electrodes and counter-electrodes, as the discharges occur only from a threshold value of the high voltage, it is arranged so that the voltage applied separately to a electrode or counter electrode is insufficient to cause a discharge alone and therefore an impression.
- the electrodes are aligned in bundles on at least one row, the electrodes of the same row of the bundles of the same row being interconnected.
- the counter electrodes are distributed along the bundles.
- a relatively large separation for example from 0.2 to 0.5 millimeter, is necessary between neighboring counter-electrodes because of the voltage values to be switched. This adversely affects printing when the requested resolution is high.
- the conductivity of the conductive base formed by the special paper there is a decrease in the electric field in the areas where the electrodes are in front of a space between counter-electrodes.
- the latent image is created on a thin insulating film, then revealed by inking according to a process identical to that mentioned above.
- the revealed image is then transferred and fixed on a sheet of plain paper, for example by pressing the sheet on the inked insulating film.
- the arrangement of the electrodes used for direct electrostatic writing is also suitable for indirect electrostatic writing, it is generally not the same with regard to the arrangement of the counter-electrodes since in this case neither the insulating film nor the paper are conductive.
- the conventional solution in indirect electrostatic writing consists in passing the insulating film, where the latent image is created, between the electrodes and the counter-electrodes which face each other.
- this solution has drawbacks, linked in particular to the complexity of the voltage control system of the assembly and to the need for precise positioning of the counter-electrodes relative to the electrodes, whereas it is advantageous with this power solution. spread the electrodes of the counter-electrodes to place the insulating film or remove it during regular film replacements that the user must carry out.
- the present invention therefore provides an electrostatic image printing head on a recording medium, in particular of the plain paper type, in which the electrodes and counter-electrodes necessary for ionic discharge are arranged on the same side of the recording medium. .
- the printhead conventionally comprises, firstly, at least one row of individual electrodes arranged in regular pitch and organized in n groups distributed in two networks, the electrodes having the same positions in the groups of a network being interconnected between they.
- the recording head conventionally comprises, secondly, at least one set of counter-electrodes aligned in parallel with the individual electrodes and each assigned to at least one group of electrodes which it runs along, so as to create a latent image on a insulating recording medium, scrolling flush with these electrodes and counter-electrodes, by ionic discharge between at least one electrode and at least one counter-electrode brought respectively to high-voltage potentials of opposite polarities by high-voltage pulses of ordered.
- the electrostatic print head comprises a rotary coupling electrode which is made of conductive material and brought to a medium-voltage direct potential, of the same polarity as the high pulses. te-tension applied to the counter electrodes, said coupling electrode being pressed against the recording medium in line with the electrodes and counter electrodes, on the other side of these relative to the recording medium.
- an electrostatic printing head usually comprises a plurality of electrodes E aligned in at least one row along which are arranged at least one and here two rows of CE counter-electrodes which border the row or rows of electrodes seen here at the end and by their active end, as well as the counter-electrodes.
- the electrodes and counter-electrodes are intended to be flush with the support for recording latent images on the same side of the strip that this support forms.
- the electrodes E which are in large number, for example 1728, are divided into n groups distributed in two networks and preferably comprising the same number r of electrodes, for example 36 groups of 48 electrodes, the number r being chosen equal to four in Figure 1 for reasons of simplification of the figure.
- the electrodes E of the same rank, in the different groups of a network are interconnected with one another, such as for example the electrodes E13, E33 or E23, En3.
- the electrodes of each network are powered up by 1 D or 2D switches which each serve a group of interconnected electrodes, such as switch 1 D3 for the electrodes E13, E33 given above as an example.
- a zero voltage OV is normally applied by each switch D to the electrodes to which it is connected, in the absence of individual control concerning them for a printing need.
- the latter is actuated so as to bring this electrode and those which are interconnected with it to a high voltage potential -V / 2, of lower value and here half of the high threshold voltage V necessary for an ionic discharge of printing.
- the counter electrodes CE other than those at the end CE1, CE1 'and CEP, CEP', are arranged along electrodes belonging to two successive groups, such as the counter electrodes CE2, CE2 'along the electrodes E13, E14 from group 1 and E21, E22 from group 2.
- the counter-electrodes are energized by switches C, here referenced from C1 to Cp, which are shown each connected to a pair of interconnected counter-electrodes of the same rank, such as C1 to the CE1 counter-electrodes. , CE1 '.
- a zero voltage OV is normally applied by each switch C to the counter-electrodes to which it is connected, in the absence of individual control concerning them for printing.
- a print command actuates the switch C, concerned, so as to bring the counter-electrodes which it serves to a high voltage potential + V / 2.
- the ionic impression discharge is therefore obtained by setting the potential -V / 2 of an electrode and the potential + V / 2 of the counter-electrodes which runs along it.
- the recording medium 1 is of the conductive layer 1 C type covered with a dielectric layer 1 D intended to be pressed against the electrode / counter-electrode assembly to store point charges, the conductive layer serving least resistive path between an electrode E and the neighboring counter-electrodes CE and CE ', for ionic discharge, via the dielectric layer (FIG. 2).
- the recording medium 1 is a thin insulating film used as an intermediate for the formation of latent images, subsequently transferred to a final medium generally made of plain paper.
- a rotary EC coupling electrode such as EC1 in FIG. 2, which is brought to a direct potential V1 of the same polarity as the control pulses applied to the counter-electrodes, so as to associate its action with their in case of order.
- the continuous potential + V1 is chosen to have a value much lower than the value + V / 2 so as not to allow the triggering of an ionic discharge between an electrode E and the coupling electrode, it is for example of the order from one hundred to two hundred and fifty volts for a voltage V of the order of five hundred to six hundred volts.
- the coupling electrode EC is arranged transversely to the direction of movement of the recording medium and covers all of the electrodes E and counter electrodes CE, of which it extends beyond the rows of electrodes and counter electrodes, these these being of course also arranged transversely with respect to the direction of movement of the recording medium, in a block of insulating material 2 which keeps them in position relative to each other.
- the recording medium is generally constituted by a very smooth thin film, a small air gap 3 is provided under the electrodes between them and the recording medium, this interval is usually obtained by grooving the block 2 to the right of the electrodes E.
- the coupling electrode EC1 consists of an endless band of flexible resistive material, of the charged elastomer type, the resistivity of which is for example of the order of 10 6 to 10 7 ohm. .
- This strip electrode is wound freely around carrier rollers 4 here three in number which allow its tension and for two of them its pressing against the recording medium 1 on and around the ends of the electrodes and counter-electrodes.
- the coupling electrode EC1 is brought to potential + V1, for example at one of its carrier rollers by contact using means known per se, of the trotter type or connection by ring and wiper.
- the support assembly 2 rollers 4 and CE1 counter electrode is mechanically positioned in a usual support frame, not shown, which will not be specified here insofar as this structure has only an indirect relationship with the invention.
- a cylindrical EC2 coupling electrode is replaced by the endless belt provided in FIG. 2.
- This coupling electrode EC2, arranged transversely or direction of movement of the recording medium 1 is produced by a tube made of flexible material having for example a hardness less than thirty shores and a diameter of the order of six centimeters.
- the flexible tube obtained is for example made of an elastomeric material having a resistivity of the order of 10 6 to 10 7 ohm-centimeters; in the alternative embodiment presented here the flexible tube 5, mounted idly on an axis 6, is covered by an outer layer of constant thickness with a value for example between 0.1 and several millimeters which has the required resistivity and which is connected to the potential + V1, for example by a ring system associated with the tube and fixed trotter which is not reproduced here because of its classicism.
- the coupling electrode EC2 is mechanically pressed for example by a spring system against the recording medium itself applied against the assembly formed by the electrodes, the counter-electrodes and the block part which contains them, it deforms under pressure so as to cover said electrodes and counter electrodes.
- a print head as defined above which allows printing on any support, after inking the latent electrostatic image, by transferring this inked image to the final support which is to carry it, allows also printing on special composite paper comprising a dielectric layer and a conductive layer joined together.
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- Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
Description
La présente invention a pour objet une tête d'impression électrostatique d'image. De telles têtes d'impression électrostatique permettent de créer progressivement une image électrostatique latente sur un support d'enregistrement diélectrique en mouvement au moyen de décharges ioniques.The present invention relates to an electrostatic image printing head. Such electrostatic printheads make it possible to gradually create a latent electrostatic image on a moving dielectric recording medium by means of ionic discharges.
De manière connue, l'impression électrostatique directe nécessite un papier spécial constitué d'une base conductrice recouverte par un film diélectrique de faible épaisseur. Une image électrostatique latente est créée sur le papier spécial par décharge ionique dans l'air au moyen d'une rangée d'électrodes de faibles dimensions portées à haute tension. L'image latente est encrée, par exemple à l'aide d'une brosse magnétique porteuse d'encre en poudre, puis fixée sur le papier spécial par pression et/ou par cuisson.In known manner, direct electrostatic printing requires a special paper consisting of a conductive base covered by a thin dielectric film. A latent electrostatic image is created on the special paper by ionic discharge in the air by means of a row of small electrodes brought to high voltage. The latent image is inked, for example using a magnetic brush carrying powdered ink, then fixed on the special paper by pressure and / or by cooking.
Pour que la décharge ionique puisse se réaliser à l'extrémité des électrodes et que les ions se déposent sur le papier spécial, une haute tension est créée entre au moins une des électrodes et au moins une contre-électrode placée à proximité de manière que le champ électrique résultant au niveau de l'électrode soit perpendiculaire à la surface du papier spécial. Dans une forme de réalisation connue, les contre-électrodes sont placées du même côté du papier spécial que les électrodes et la décharge s'effectue par effet capacitif des contre-électrodes au travers du film diélectrique dont est doté le papier spécial et en raison de la conduction de la base conductrice de ce papier spécial.In order for the ionic discharge to take place at the end of the electrodes and for the ions to be deposited on the special paper, a high voltage is created between at least one of the electrodes and at least one counter-electrode placed nearby so that the resulting electric field at the electrode is perpendicular to the surface of the special paper. In a known embodiment, the counter-electrodes are placed on the same side of the special paper as the electrodes and the discharge takes place by the capacitive effect of the counter-electrodes through the dielectric film with which the special paper is provided and due to conduction of the conductive base of this special paper.
Les électrodes individuelles utilisées dans la tête d'impression sont de dimensions très faibles et en nombre élevé, pour une ligne d'image de longueur donnée, de manière à permettre par exemple l'impression de huit points au millimètre.The individual electrodes used in the print head are of very small dimensions and in large number, for an image line of given length, so as to allow for example the printing of eight dots per millimeter.
La haute tension nécessaire aux décharges ioniques est préférablement partagée entre électrodes et contre-électrodes, comme les décharges ne se produisent qu'à partir d'une valeur de seuil de la haute tension, on s'arrange pour que la tension appliquée isolément à une électrode ou à une contre électrode soit insuffisante pour provoquer à elle seule une décharge et donc une impression.The high voltage necessary for ionic discharges is preferably shared between electrodes and counter-electrodes, as the discharges occur only from a threshold value of the high voltage, it is arranged so that the voltage applied separately to a electrode or counter electrode is insufficient to cause a discharge alone and therefore an impression.
Les électrodes sont alignées par paquets sur au moins une rangée, les électrodes de même rang des paquets d'une même rangée étant interconnectées. Les contre-électrodes sont réparties le long des paquets.The electrodes are aligned in bundles on at least one row, the electrodes of the same row of the bundles of the same row being interconnected. The counter electrodes are distributed along the bundles.
Une séparation relativement importante, par example de 0,2 à 0,5 millimètre, est nécessaire entre contre-électrodes voisines en raison des valeurs de tension à commuter. Ceci influe défavorablement sur l'impression lorsque la résolution demandée est élevée. En effet malgré la conductivité de la base conductrice comportée par le papier spécial, il y a diminution du champ électrique dans les zones où des électrodes sont en face d'un espace entre contre-électrodes.A relatively large separation, for example from 0.2 to 0.5 millimeter, is necessary between neighboring counter-electrodes because of the voltage values to be switched. This adversely affects printing when the requested resolution is high. In fact, despite the conductivity of the conductive base formed by the special paper, there is a decrease in the electric field in the areas where the electrodes are in front of a space between counter-electrodes.
Il est connu de minimiser cet inconvénient par positionnement des électrodes.en deux réseaux comportant un même nombre de paquets qui s'alternent et par mise en oeuvre de contre-électrodes décalées en position d'une valeur correspondant à un demi-paquet le long des paquets, de manière à longer deux demi-paquets successifs, ces contres- électrodes sont simultanément commutées de part et d'autre d'un paquet.It is known to minimize this drawback by positioning the electrodes in two networks comprising the same number of alternating packets and by using counter-electrodes offset in position by a value corresponding to half a packet along the packets, so as to go along two successive half-packets, these counter-electrodes are simultaneously switched on either side of a packet.
En écriture électrostatique indirecte, l'image latente est créée sur un film isolant de faible épaisseur, puis révélée par encrage selon un processus identique à celui évoqué plus haut. L'image révélée est ensuite transférée et fixée sur une feuille de papier ordinaire par exemple par pression de la feuille sur le film isolant encré.In indirect electrostatic writing, the latent image is created on a thin insulating film, then revealed by inking according to a process identical to that mentioned above. The revealed image is then transferred and fixed on a sheet of plain paper, for example by pressing the sheet on the inked insulating film.
La disposition des électrodes retenues pour l'écriture électrostatique directe convient également en écriture électrostatique indirecte, il n'en est généralement pas de même en ce qui concerne la disposition des contre-électrodes puisque dans ce cas ni le film isolant, ni le papier ne sont conducteurs.The arrangement of the electrodes used for direct electrostatic writing is also suitable for indirect electrostatic writing, it is generally not the same with regard to the arrangement of the counter-electrodes since in this case neither the insulating film nor the paper are conductive.
En conséquence, la solution classique en écriture électrostatique indirecte consiste à faire passer le film isolant, où l'image latente est créée, entre les électrodes et les contre-électrodes qui se font face.Consequently, the conventional solution in indirect electrostatic writing consists in passing the insulating film, where the latent image is created, between the electrodes and the counter-electrodes which face each other.
Toutefois cette solution présente des inconvénients, liés notamment à la complexité du système de commande en tension de l'ensemble et à la nécessité d'un positionnement précis des contre-électrodes par rapport aux électrodes alors qu'il est avantageux avec cette solution de pouvoir écarter les électrodes des contre-électrodes pour placer le film isolant ou l'ôter lors des remplacements réguliers de film que doit effectuer l'utilisateur.However, this solution has drawbacks, linked in particular to the complexity of the voltage control system of the assembly and to the need for precise positioning of the counter-electrodes relative to the electrodes, whereas it is advantageous with this power solution. spread the electrodes of the counter-electrodes to place the insulating film or remove it during regular film replacements that the user must carry out.
Il est donc préférable à ce point de vue de pouvoir placer les électrodes et les contre-électrodes du même côté du film.It is therefore preferable from this point of view to be able to place the electrodes and the counter-electrodes on the same side of the film.
La présente invention propose donc une tête d'impression électrostatique d'image sur support d'enregistrement, notamment de type papier ordinaire, dans lequel les électrodes et les contre-électrodes nécessaires à la décharge ionique sont disposées du même côté du support d'enregistrement.The present invention therefore provides an electrostatic image printing head on a recording medium, in particular of the plain paper type, in which the electrodes and counter-electrodes necessary for ionic discharge are arranged on the same side of the recording medium. .
La tête d'impression comporte classiquement, en premier lieu, au moins une rangée d'électrodes individuelles disposées à pas régulier et organisées en n groupes répartis dans deux réseaux, les électrodes ayant les mêmes positions dans les groupes d'un réseau étant interconnectées entre elles. La tête d'enregistrement comporte classiquement, en second lieu, au moins un ensemble de contre-électrodes alignées parallèlement aux électrodes individuelles et affectées chacune à au moins un groupe d'électrodes qu'elle longe, de manière à créer une image latente sur un support d'enregistrement isolant, défilant au ras de ces électrodes et contre-électrodes, par décharge ionique entre au moins une électrode et au moins une contre-électrode portées respectivement à des potentiels haute-tension de polarités opposées par des impulsions haute-tension de commande.The printhead conventionally comprises, firstly, at least one row of individual electrodes arranged in regular pitch and organized in n groups distributed in two networks, the electrodes having the same positions in the groups of a network being interconnected between they. The recording head conventionally comprises, secondly, at least one set of counter-electrodes aligned in parallel with the individual electrodes and each assigned to at least one group of electrodes which it runs along, so as to create a latent image on a insulating recording medium, scrolling flush with these electrodes and counter-electrodes, by ionic discharge between at least one electrode and at least one counter-electrode brought respectively to high-voltage potentials of opposite polarities by high-voltage pulses of ordered.
Selon une caractéristique de l'invention, la tête d'impression électrostatique comporte une électrode rotative de couplage qui est réalisée en matériau conducteur et portée à un potentiel continu moyenne tension, de même polarité que les impulsions haute-tension appliquées aux contre-électrodes, ladite électrode de couplage étant plaquée contre le support d'enregistrement au droit des électrodes et contre-électrodes, de l'autre côté de celles-ci par rapport au support d'enregistrement.According to a characteristic of the invention, the electrostatic print head comprises a rotary coupling electrode which is made of conductive material and brought to a medium-voltage direct potential, of the same polarity as the high pulses. te-tension applied to the counter electrodes, said coupling electrode being pressed against the recording medium in line with the electrodes and counter electrodes, on the other side of these relative to the recording medium.
L'invention, ses caractéristiques et ses avantages sont précisés dans la description qui suit en liaison avec les figures répertoriées ci-dessous.
- La figure 1 présente un schéma précisant la position respective des électrodes et contre-électrodes d'une tête d'impression électrostatique à électrodes et contre-électrodes situées du même côté du support d'enregistrement ainsi que leurs liaisons de commande.
- Les figures 2 et 3 présentent chacune une coupe transversale d'une tête d'impression électrostatique selon deux variantes différentes de l'invention.
- FIG. 1 presents a diagram specifying the respective position of the electrodes and counter-electrodes of an electrostatic printing head with electrodes and counter-electrodes situated on the same side of the recording medium as well as their control links.
- Figures 2 and 3 each show a cross section of an electrostatic print head according to two different variants of the invention.
De manière connue, décrite notamment dans la demande de brevet européen EP-A- 0124856, une tête d'impression électrostatique comporte usuellement une pluralité d'électrodes E alignées en au moins une rangée le long de laquelle sont disposées au moins un et ici deux rangs de contre-électrodes CE qui bordent le ou les rangs d'électrodes vues ici en bout et par leur extrémité active, de même que les contre-électrodes.In a known manner, described in particular in European patent application EP-A-0124856, an electrostatic printing head usually comprises a plurality of electrodes E aligned in at least one row along which are arranged at least one and here two rows of CE counter-electrodes which border the row or rows of electrodes seen here at the end and by their active end, as well as the counter-electrodes.
Comme indiqué plus haut les électrodes et contre-électrodes sont destinées à venir affleurer le support d'enregistrement d'images latentes du même côté de la bande que forme ce support.As indicated above, the electrodes and counter-electrodes are intended to be flush with the support for recording latent images on the same side of the strip that this support forms.
Les électrodes E qui sont en grand nombre, par exemple au nombre de 1728, sont divisées en n groupes répartis dans deux réseaux et comportant préférablement un même nombre r d'électrodes par exemple 36 groupes de 48 électrodes, le nombre r étant choisi égal à quatre sur la figure 1 pour des raisons de simplification de la figure.The electrodes E which are in large number, for example 1728, are divided into n groups distributed in two networks and preferably comprising the same number r of electrodes, for example 36 groups of 48 electrodes, the number r being chosen equal to four in Figure 1 for reasons of simplification of the figure.
Dans la forme de réalisation présentée, les électrodes E de même rang, dans les différents groupes d'un réseau, sont interconnectées entre elles, telles par exemple les électrodes E13, E33 ou E23, En3. La mise sous tension des électrodes de chaque réseau s'effectue par l'intermédiaire de commutateurs 1 D ou 2D qui desservent chacun un groupe d'électrodes interconnectées, tel le commutateur 1 D3 pour les électrodes E13, E33 données ci-dessus en exemple.In the embodiment presented, the electrodes E of the same rank, in the different groups of a network, are interconnected with one another, such as for example the electrodes E13, E33 or E23, En3. The electrodes of each network are powered up by 1 D or 2D switches which each serve a group of interconnected electrodes, such as
Une tension nulle OV est normalement appliquée par chaque commutateur D aux électrodes auxquelles il est relié, en l'absence de commande individuelle les concernant pour un besoin d'impression. Lorsqu'une impression doit être effectuée par une électrode reliée à un commutateur 1 D ou 2D, ce dernier est actionné de manière à porter cette électrode et celles qui sont interconnectées avec elle à un potentiel haute tension -V/2, de valeur inférieure et ici moitié de la haute tension V de seuil nécessaire à une décharge ionique d'impression.A zero voltage OV is normally applied by each switch D to the electrodes to which it is connected, in the absence of individual control concerning them for a printing need. When printing must be carried out by an electrode connected to a 1 D or 2D switch, the latter is actuated so as to bring this electrode and those which are interconnected with it to a high voltage potential -V / 2, of lower value and here half of the high threshold voltage V necessary for an ionic discharge of printing.
Les contre-électrodes CE disposées de part et d'autre des électrodes E sont réparties ici en p = n+1 groupes de deux contre-électrodes de même rang interconnectées, telles les deux contre-électrodes CE1 et CE1'.The counter electrodes CE placed on either side of the electrodes E are distributed here in p = n + 1 groups of two counter electrodes of the same rank interconnected, such as the two counter electrodes CE1 and CE1 '.
Les contre-électrodes CE autres que celles d'extrémité CE1, CE1' et CEP, CEP', sont disposées le long d'électrodes appartenant à deux groupes successifs, telles les contre-électrodes CE2, CE2' le long des électrodes E13, E14 du groupe 1 et E21, E22 du groupe 2.The counter electrodes CE other than those at the end CE1, CE1 'and CEP, CEP', are arranged along electrodes belonging to two successive groups, such as the counter electrodes CE2, CE2 'along the electrodes E13, E14 from
La mise sous tension des contre-électrodes s'effectue par l'intermédiaire de commutateurs C, ici référencés de C1 à Cp, qui sont montrés reliés chacun à une paire de contre-électrodes de même rang interconnectées, tel C1 aux contre-électrodes CE1, CE1'. Une tension nulle OV est normalement appliquée par chaque commutateur C aux contre-électrodes aux quelles il est relié, en l'absence de commande individuelle les concernant en vue d'une impression. Par contre une telle commande d'impression actionne le commutateur C, concerné, de manière à porter les contre-électrodes qu'il dessert à un potentiel haute tension +V/2.The counter-electrodes are energized by switches C, here referenced from C1 to Cp, which are shown each connected to a pair of interconnected counter-electrodes of the same rank, such as C1 to the CE1 counter-electrodes. , CE1 '. A zero voltage OV is normally applied by each switch C to the counter-electrodes to which it is connected, in the absence of individual control concerning them for printing. On the other hand, such a print command actuates the switch C, concerned, so as to bring the counter-electrodes which it serves to a high voltage potential + V / 2.
La décharge ionique d'impression est donc obtenue par mise au potentiel -V/2 d'une électrode et au potentiel +V/2 des contre-électrodes qui la longe.The ionic impression discharge is therefore obtained by setting the potential -V / 2 of an electrode and the potential + V / 2 of the counter-electrodes which runs along it.
Ceci est suffisant si le support d'enregistrement 1 est de type à couche conductrice 1 C recouverte d'une couche diélectrique 1 D destinée à venir se plaquer contre l'ensemble électrodes/contre-électrodes pour emmagasiner des charges ponctuelles, la couche conductrice servant de chemin le moins résistif entre une électrode E et les contre-électrodes CE et CE' voisines, pour la décharge ionique, via la couche diélectrique (figure 2).This is sufficient if the
Ceci n'est pas suffisant si le support d'enregistrement 1 est un film isolant mince utilisé à titre intermédiaire pour la formation des images latentes, ultérieurement transférées sur un support définitif généralement en papier ordinaire.This is not sufficient if the
Selon l'invention on prévoit donc une électrode de couplage EC rotative, telle EC1 sur la figure 2, qui est portée à un potentiel continu V1 de même polarité que les impulsions de commande appliquées aux contre-électrodes, de manière à associer son action aux leurs en cas de commande.According to the invention there is therefore provided a rotary EC coupling electrode, such as EC1 in FIG. 2, which is brought to a direct potential V1 of the same polarity as the control pulses applied to the counter-electrodes, so as to associate its action with their in case of order.
Le potentiel continu +V1 est choisi de valeur largement inférieure à la valeur +V/2 de manière à ne pas permettre le déclenchement d'une décharge ionique entre une électrode E et l'électrode de couplage, il est par exemple de l'ordre de cent à deux cent cinquante volts pour une tension V de l'ordre de cinq cent à six cent volts.The continuous potential + V1 is chosen to have a value much lower than the value + V / 2 so as not to allow the triggering of an ionic discharge between an electrode E and the coupling electrode, it is for example of the order from one hundred to two hundred and fifty volts for a voltage V of the order of five hundred to six hundred volts.
L'électrode de couplage EC est disposée transversalement par rapport au sens de déplacement du support d'enregistrement et vient recouvrir l'ensemble des électrodes E et contre-électrodes CE, dont elle déborde les rangées d'électrodes et contre-électrodes, celles-ci étant bien entendu elles aussi disposées transversalement par rapport au sens de déplacement du support d'enregistrement, dans un bloc en matériau isolant 2 qui les maintient en position les unes par rapport aux autres.The coupling electrode EC is arranged transversely to the direction of movement of the recording medium and covers all of the electrodes E and counter electrodes CE, of which it extends beyond the rows of electrodes and counter electrodes, these these being of course also arranged transversely with respect to the direction of movement of the recording medium, in a block of
Dans la mesure où le support d'enregistrement est généralement constitué par un film mince très lisse, on prévoit un petit intervalle d'air 3 sous les électrodes entre celles-ci et le support d'enregistrement, cet intervalle est usuellement obtenu par rainurage du bloc 2 au droit des électrodes E.Since the recording medium is generally constituted by a very smooth thin film, a small air gap 3 is provided under the electrodes between them and the recording medium, this interval is usually obtained by grooving the
Dans la forme de réalisation présentée figure 2, l'électrode de couplage EC1 est constituée par une bande sans fin en matériau résistif souple, de type élastomère chargé, dont la résistivité est par exemple de l'ordre de 106 à 107 ohm.centimètre. Cette électrode en bande s'enroule librement autour de rouleaux porteurs 4 ici au nombre de trois qui permettent sa tension et pour deux d'entre eux son plaquage contre le support d'enregistrement 1 sur et autour des extrémités des électrodes et contre-électrodes. L'électrode de couplage EC1 est portée au potentiel +V1 par exemple au niveau de l'un de ses rouleaux porteurs par contact à l'aide de moyens connus en eux-même, de type trotteur ou connexion par bague et frotteur. L'ensemble support 2 rouleaux 4 et contre-électrode CE1 est mécaniquement positionné dans un bâti-support usuel, non figuré qui ne sera pas précisé ici dans la mesure où cette structure n'a qu'un rapport indirect avec l'invention.In the embodiment presented in FIG. 2, the coupling electrode EC1 consists of an endless band of flexible resistive material, of the charged elastomer type, the resistivity of which is for example of the order of 10 6 to 10 7 ohm. . This strip electrode is wound freely around carrier rollers 4 here three in number which allow its tension and for two of them its pressing against the
Dans la forme de réalisation présentée figure 3, on substitue une électrode de couplage EC2 cylindrique à la bande sans fin prévue en figure 2.In the embodiment presented in FIG. 3, a cylindrical EC2 coupling electrode is replaced by the endless belt provided in FIG. 2.
Cette électrode de couplage EC2, disposée transversalement ou sens de déplacement du support d'enregistrement 1 est réalisé par un tube en matériau souple présentant par exemple une dureté inférieure à trente shores et un diamètre de l'ordre de six centimètres.This coupling electrode EC2, arranged transversely or direction of movement of the
Le tube souple obtenu est par exemple en un matériau élastomère présentant une résistivité de l'ordre de 106 à 107 ohm-centimètre ; dans la variante de réalisation présentée ici le tube souple 5, monté fou sur un axe 6, est recouvert par une couche extérieure d'une épaisseur constante d'une valeur comprise par exemple entre 0,1 et plusieurs millimètres qui présente la résistivité requise et qui est reliée au potentiel +V1, par exemple par un système à bague associée au tube et trotteur fixe qui n'est par reproduit ici en raison de son classicisme.The flexible tube obtained is for example made of an elastomeric material having a resistivity of the order of 10 6 to 10 7 ohm-centimeters; in the alternative embodiment presented here the flexible tube 5, mounted idly on an
L'électrode de couplage EC2 est pressée mécaniquement par exemple par un système à ressort contre le support d'enregistrement lui-même appliqué contre l'ensemble formé par les électrodes, les contre-électrodes et la partie de bloc qui les contient, elle se déforme sous la pression de manière à recouvrir lesdites électrodes et contre-électrodes.The coupling electrode EC2 is mechanically pressed for example by a spring system against the recording medium itself applied against the assembly formed by the electrodes, the counter-electrodes and the block part which contains them, it deforms under pressure so as to cover said electrodes and counter electrodes.
Le support d'enregistrement qui frotte contre l'électrode de couplage EC1 ou EC2 lors de l'enregistrement d'images latentes, entraîne cette électrode usuellement montée folle. Il est bien entendu envisageable d'entraîner en rotation l'électrode de couplage par tout moyen classique pour réduire quasi-totalement le frottement du support d'enregistrement à son niveau.The recording medium which rubs against the coupling electrode EC1 or EC2 during the recording of latent images, drives this usually mounted electrode madly. It is of course conceivable to drive the coupling electrode in rotation by any conventional means in order to almost completely reduce the friction of the recording medium at its level.
Bien entendu, une tête d'impression telle que définie ci-dessus-qui permet l'impression sur un support quelconque, après encrage de l'image électrostatique latente, par report de cette image encrée sur le support final qui doit la porter, permet également l'impression sur papier spécial composite comportant une couche diélectrique et une couche conductrice accolées.Of course, a print head as defined above which allows printing on any support, after inking the latent electrostatic image, by transferring this inked image to the final support which is to carry it, allows also printing on special composite paper comprising a dielectric layer and a conductive layer joined together.
Claims (4)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8515978A FR2589273B1 (en) | 1985-10-28 | 1985-10-28 | ELECTROSTATIC IMAGE PRINTHEAD |
| FR8515978 | 1985-10-28 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0221452A1 EP0221452A1 (en) | 1987-05-13 |
| EP0221452B1 true EP0221452B1 (en) | 1990-05-02 |
Family
ID=9324262
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP86114690A Expired - Lifetime EP0221452B1 (en) | 1985-10-28 | 1986-10-23 | Electrostatic-image print head |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4727386A (en) |
| EP (1) | EP0221452B1 (en) |
| DE (1) | DE3670792D1 (en) |
| FR (1) | FR2589273B1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0329965A (en) * | 1989-06-28 | 1991-02-07 | Matsushita Graphic Commun Syst Inc | Electrostatic latent image forming device |
| US4977416A (en) * | 1989-09-21 | 1990-12-11 | Rastergraphics, Inc. | Integrated thick film electrostatic writing head |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5814160A (en) * | 1981-07-17 | 1983-01-26 | Ricoh Co Ltd | Electrostatic recording method |
| FR2545759A1 (en) * | 1983-05-09 | 1984-11-16 | Cit Alcatel | ELECTROSTATIC PRINTING HEAD |
-
1985
- 1985-10-28 FR FR8515978A patent/FR2589273B1/en not_active Expired
-
1986
- 1986-10-23 DE DE8686114690T patent/DE3670792D1/en not_active Expired - Lifetime
- 1986-10-23 EP EP86114690A patent/EP0221452B1/en not_active Expired - Lifetime
- 1986-10-28 US US06/923,928 patent/US4727386A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| FR2589273A1 (en) | 1987-04-30 |
| DE3670792D1 (en) | 1990-06-07 |
| FR2589273B1 (en) | 1987-12-11 |
| EP0221452A1 (en) | 1987-05-13 |
| US4727386A (en) | 1988-02-23 |
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