EP0321677B1 - Components for a supply circuit for an ink jet printer - Google Patents

Abstract

PCT No. PCT/FR88/00522 Sec. 371 Date Jun. 20, 1989 Sec. 102(e) Date Jun. 20, 1989 PCT Filed Oct. 25, 1988 PCT Pub. No. WO89/05728 PCT Pub. Date Jun. 29, 1989.A device is provided for receiving a combination of two variable volume chambers and a plurality of valves for forming an ink supply circuit for an ink jet printing head. Such a device is formed by a solid one-piece block comprising a plurality of cavities which are disposed radially about a central housing receiving both a piston (P) and a pressure sensor (5). The piston (P) being formed by the stacking of at least two pieces of diameter O1 and O2 and two membranes clamped by two flanges, the whole defining two variable volume chambers. This device cooperates with a reservoir block having two compartments between which moves a link connected on one side to an eccentric and on the other to the piston for forming an extremely reliable and compact ink supply circuit.

Description

The invention relates to a device for receiving a combination of two variable volume chambers and a plurality of valves for constituting an ink supply circuit of an ink jet print head.

The Applicant has described in a French patent application No. 86 17385 filed on 10.2.1986, supplemented by a request for Certificate of Addition No. 87 12008 filed on 26.08.1987, a fluid supply circuit of a head inkjet printing equipped with a multi-function cell consisting in particular of two chambers, the volume of which varies according to the position of a single piston coupled to the same eccentric driven by the same motor. We find described in these two requests, all the means: chambers, valves, restriction, reservoir, etc. necessary to obtain all the functions necessary for the proper functioning of an inkjet print head.

To further enhance the performance of such a combination, it is important to produce the assembly in a volume as compact as possible.

The present invention aims to solve this problem and relates to an arrangement of all the means used in a structure which is easy to produce, simple and which leads to an extremely compact final device.

• ledit logement central cylindrique comportant une première zone de diamètre ⌀₁ et une seconde zone de diamètre ⌀₂ dans lesquelles peut se mouvoir un piston (P), qui comprend deux parties empilées de diamètres respectifs ⌀₁ et ⌀₂, lesdites deux parties définissant à l'intérieur desdites zones par l'intermédiaire de deux membranes étanches, lesdites deux chambres à volume variable;
• une pluralité de cavités destinées à recevoir les valves et disposées radialement par rapport à l'axe du piston, des premières cavités étant disposées en étoile, de forme et de volume identiques et dont les bases sont situées dans un même plan horizontal, et des secondes cavités étant situées dans un deuxième plan;
• un logement destiné à recevoir le capteur de pression.

The invention relates more precisely to a device intended to receive two variable volume chambers and a pressure sensor, cooperating with a plurality of valves to ensure the proper functioning of an ink supply circuit of a print head with jet of ink and of recovery of the unused ink at the level of the recovery gutter, said device comprising a cylindrical housing in which a piston can move defining two chambers with variable volume by means of two waterproof membranes interior of the accommodation, and
being characterized in that it consists of a solid monobloc piece of material resistant to chemical attack, in which are made in a compact manner:

• said cylindrical central housing comprising a first zone of diameter ⌀₁ and a second zone of diameter ⌀₂ in which a piston (P) can move, which comprises two stacked parts of respective diameters ⌀₁ and ⌀₂, said two parts defining the interior of said zones by means of two waterproof membranes, said two variable volume chambers;
• a plurality of cavities intended to receive the valves and arranged radially with respect to the axis of the piston, first cavities being arranged in a star, of identical shape and volume and whose bases are located in the same horizontal plane, and seconds cavities being located in a second plane;
• a housing intended to receive the pressure sensor.

• la figure 1, séparée en deux figures 1a et 1b, rappelle le fonctionnement d'une chambre à volume variable telle que décrit dans les demandes de brevets référencées ci-dessus;
• la figure 2 illustre schématiquement une variante de réalisation d'un circuit d'alimentation en encre d'une tête d'impression destiné à être intégré dans un dispositif selon l'invention;
• les figures 3, 4 et 5 illustrent la structure du dispositif conforme à la présente invention;
• les figures 6 et 7 sont des schémas illustratifs complémentaires des figures 2 à 5:
• les figures 8 et 9 sont des coupes selon des plans parallèles à la base du dispositif, réalisées à deux niveaux;
• la figure 10 est une vue en section d'un ensemble équipé d'un dispositif conforme à l'invention.

The invention will be better understood with the aid of the explanations which follow and of the appended figures among which:

• Figure 1, separated into two Figures 1a and 1b, recalls the operation of a variable volume chamber as described in the patent applications referenced above;
• Figure 2 schematically illustrates a variant of production of a circuit for supplying ink to a print head intended to be integrated into a device according to the invention;
• Figures 3, 4 and 5 illustrate the structure of the device according to the present invention;
• Figures 6 and 7 are additional illustrative diagrams of Figures 2 to 5:
• Figures 8 and 9 are sections along planes parallel to the base of the device, made at two levels;
• Figure 10 is a sectional view of an assembly equipped with a device according to the invention.

For clarity, the same elements are given the same references in all the figures.

A cell as described in the two cited patent applications is illustrated by means of Figures 1a and 1b. It essentially consists of a chamber (1) with variable volume depending on the displacement of a piston (P). The latter is mechanically connected by means (2) to an eccentric (3) driven by a stepping motor (4). This variable volume (1) is connected on the one hand to a pressure sensor (5), and on the other hand by a pipe (6) to one, two or more valves electrically controlled by coils (b). Only two valves (7) and (9) are represented in FIGS. 1a and 1b, but this number is not restrictive and the application described below will moreover clearly show the use of a plurality of valves associated with a single room. These valves accept both directions of fluid circulation and are normally closed in the absence of an electrical signal.

The position of the drawer (t) shows for example that the valve (7) is in the blocking position in FIG. 1b and in the open position in the figure. 1a, and vice versa for the valve (9). Finally, on the outlet pipes of each valve is normally provided a throttle (8,10). These throttles are designed so as to create a pressure difference at their ends when a flow of fluid of non-zero viscosity passes through them, which can be expressed in terms of pressure drop. They are capable in particular of demonstrating, in the form of a pressure difference (ΔP), the viscosity of the fluid during a pulse of fluid flow. These throttles can for example consist of a tube integrated in series in the hydraulic circuit, this tube having a length significantly greater than the diameter of said tube. For example, the length is approximately 15 times the diameter of the tube through which the fluid passes. The arrows (F₃) and (F₄) symbolize the flow.

The generation of a fluid flow is done in two half-cycles. The first (Figure 1a) consists in controlling the opening of the valve (7) during the half-turn of the motor rotor from a 0 ° position to a 180 ° position, i.e. the time when the volume of the chamber (1 ) increases; the fluid is sucked in (arrow (F₃). The second half-cycle (Figure 1b) consists in controlling the opening of the valve (9) during the next half-turn of the motor rotor from 180 ° to 360 °, i.e. time the volume of the chamber decreases; the fluid is discharged (arrow F₄). Under these conditions, a flow of fluid can be generated in both directions by reversing the operation of the valves (7) and (9), or else can if you keep one of the two valves open and the other closed while the engine is running, these three particular operating modes are essential for the application described later. add other valve-throttle couples on the same variable volume chamber, in order to create a multi-inlet / multi-outlet pumping system, as described in the applications for main patent and certificate of addition cited above.

Among the other functions that such a cell can play, mention may also be made of emptying a pressure tank to the benefit in particular of another tank. It suffices for this to simultaneously open the two valves associated respectively with these two reservoirs.

In addition, the configuration of a circuit implementing such a cell allows direct measurement of a pressure by means of the sensor (5) by direct connection of the chamber (1) with the member whose pressure. The valve which controls this downstream organ is then maintained in the open position, the engine is stopped and the pressure sensor (5) is then directly in communication, via the chamber, with said member.

An alternative embodiment of such a circuit is illustrated by means of FIG. 2 in a static configuration, all the valves being in the closed position. This circuit includes four tanks, two of which are removable. The reservoir (15) is a cartridge containing ink (30) in reserve, not yet used. The reservoir (15) is removable. The reservoir (16) is a cartridge containing the pure solvent (31) of the ink used. This reserve solvent (31) makes it possible to top up the solvent necessary for maintaining the viscosity of the ink used and recycled in the system. The viscosity of the ink of the jet is linked to an evaporation of the solvent during the recycling of the ink. This reservoir (16) is also removable.

The reservoir (18) containing the ink (34) functionally fulfills the role of a pressure accumulator which is used in order to transform the pulsed flow rate of the cell when it is used in the pumping cell, into a constant flow rate at fixed pressure, and directly intended for forming the jet (21). This reservoir contains a pocket of air (180) under pressure which acts as a shock absorber. This air pocket (180) is renewed each time the printer is started.

The role of the reservoir (17) is to receive the recovery ink (33) and the air returning from the gutter (22), and to separate them. The ink necessary to maintain the pressure in the accumulator (18) is taken from this reservoir.

Each of these four reservoirs (15, 16, 17, 18) is connected, by a general pipe (66), to a first variable-volume chamber (1) by means of a valve-restriction pair (9-10 ) for the reservoir (18); (7-8) for the reservoir (17); (11-12) for the tank (16); and (13-14) for the reservoir (15). This set, the heart of which is the chamber (1), bears the general reference (A).

A second variable volume chamber (23) also cooperates with a plurality of valves. This combination is referenced (B).

This second chamber (23) is combined with a set of two valves (24,25). This chamber being mechanically coupled to the eccentric (3) common to the first chamber (1), the synchronism of the valves which are attached to it follows from the synchronism of the chamber (1). Such a combination of two sets (A) and (B), therefore coupled to a single motor (4) and a single sensor (5) contributes to the compactness of the circuit. A pipe (220) connects the reservoir (17), called the buffer reservoir, directly to the recovery gutter (22). This reservoir (17) can be placed under vacuum. A valve (26) is connected on one side to the pipe (66), and on the other to a condenser (300) comprising a receptacle for the condensate (301) and an evacuation (303) of volatile products.

The pressure sensor (5) is connected to this first chamber (1) and allows a whole set of controls and measurements. As has been said in the cited patent applications, one of the characteristics of this supply circuit is that it has only one sensor, the pressure sensor (5), and that this single sensor (5) allows all the measures necessary for the proper functioning of the assembly, namely the pressure measurement of the ink supplying the jet, the viscosity measurement of the ink, the level control of the reservoir (18) during the regeneration of the air pocket, measurement of empty tank level (17), measurement of low level and empty level of solvent tank (16), measurement of ink viscosity of tank (15), related parameter in particular at the temperature, the measurement of the low level and of the empty level of the ink tank (15), the synchronism of operation of the valves with the position of the rotor of the engine (4). As can be seen, and it should also be emphasized, this single pressure sensor (5) alone replaces all the sensors that are necessarily encountered in supply circuits of currently known types.

The functions of the valves (19) and (28) are directly linked to the operation of the jet (21) emitted by the print head (T) and are part of the known art, in particular by French patent application 8316440 filed by the Applicant and published under the number 2.553.341. For this, this combination is fictitiously isolated from the rest of the circuit by means of a rectangle (150) in broken lines. Note that the valve (19) is respectively connected to the pressure tank (18) on the one hand, and to the head (T) which generates the ink jet (21) on the other hand, and the valve (28 ) is connected to this head (T) and to the reservoir (17) via the pipe (170).

It should be noted beforehand that, in all cases, except when this is indicated, the motor (4) rotates at constant speed cyclically, so that the two variable volume chambers (1) and (23), which are mechanically coupled, each generating their volume cyclically. This rotation cycle has a stop at each turn for the time necessary to the measurement of a static pressure, pressure measurement not influenced by the differential pressures induced by flow rates in the throttles (8), (10), (12) and (14). This allocated time allows the measurement of static pressures, of the ink of the cartridge (30), of the solvent of the cartridge (31), and of the ink under pressure (34) of the reservoir (18).

• a) Maintien de la pression de l'accumulateur (18) durant le fonctionnement du jet ;
• b) Mesure de la viscosité de l'encre alimentant le jet et ajustement de cette viscosité en fonction d'une valeur de consigne donnée ;
• c) Mesure du niveau du réservoir (17) et ajout d'encre dans le réservoir (18) ;
• d) Mesure des niveaux bas et vide des cartouches (15) et (16) ;
• e) Aspiration du jet au niveau de la gouttière (22) ;
• f) Aspiration du condensat et sa récupération dans le réservoir (17);
• g) Maintien de la poche d'air sous pression nécessaire au fonctionnement de l'accumulateur (18) ;
• h) Procédure automatique d'arrêt court ;
• i) Procédure automatique de nettoyage complet, arrêt long ou changement d'encre.

The essential operating cycles are therefore carried out by electrically controlling the various valves synchronously with the instantaneous position of the motor rotor (4) as described in the patent applications cited above. It is thus possible to obtain control of the following functions:

• a) Maintaining the pressure of the accumulator (18) during the operation of the jet;
• b) Measuring the viscosity of the ink supplying the jet and adjusting this viscosity as a function of a given set value;
• c) Measuring the level of the reservoir (17) and adding ink to the reservoir (18);
• d) Measuring the low and empty levels of the cartridges (15) and (16);
• e) Suction of the jet at the level of the gutter (22);
• f) Suction of the condensate and its recovery in the tank (17);
• g) Maintaining the air pocket under pressure necessary for the operation of the accumulator (18);
• h) Automatic short stop procedure;
• i) Automatic complete cleaning procedure, long shutdown or ink change.

The present invention relates to a device intended to receive all the elements of the ink circuit previously described and directly intended to cooperate with the two chambers (1) and (23) belonging respectively to the element (A) said pressure pump , and to element (B) said vacuum pump.

According to a characteristic of the invention, this device (100) consists of a single piece of parallelepipedal shape made of an electrically insulating material and resistant to chemical attack such as for example Polyphenylene Sulfide said PPS. The device (100) according to the invention is first illustrated by means of FIGS. 3, 4 and 5 which, by drawing artifices, make it possible to see the housings and cavities produced inside the one-piece part by removal of material which, in reality, surrounds these dwellings. This representation is made for the sake of clarity and for a better understanding of the invention, without having to resort to too high a number of sections and sections which would weigh down and confuse the description.

• un logement central (202) cylindrique comportant deux zones de diamètres (⌀₁) et (⌀₂) respectifs, dans lequel peut se mouvoir le piston (P), permet la délimitation, en combinaison avec deux membranes visibles sur la figure 10, des deux chambres à volume variable, à savoir la chambre (1) de diamètre (⌀₁) et la chambre (23) de diamètre (⌀₂);
• une pluralité de cavités dites radiales, de même forme et de même volume intérieur, dont les bases sont situées dans un même premier plan horizontal, cette pluralité de cavités étant disposée en étoile par rapport au logement cylindrique central (202);
• une cavité sensiblement de même forme que les précédentes mais dont le volume intérieur est double et situé dans un plan différent du précédent. Mais il pourrait s'agir de deux cavités séparées. Ces cavités radiales sont destinées à recevoir une ou deux valves et portent la référence de la valve concernée affectée d'un indice (a).

It should however be noted that, when necessary for this good understanding, the housing or the cavity represented carries the reference of the element which occupies it in reality: this is the case, for example, of the piston (P ) and its housing (202). This part (100) therefore comprises, produced in its mass, a plurality of housings and cavities distributed as follows:

• a cylindrical central housing (202) comprising two zones of diameters (⌀₁) and (⌀₂) respectively, in which the piston (P) can move, allows the delimitation, in combination with two membranes visible in FIG. 10, of the two variable volume chambers, namely the chamber (1) of diameter (⌀₁) and the chamber (23) of diameter (⌀₂);
• a plurality of so-called radial cavities, of the same shape and of the same internal volume, the bases of which are situated in the same first horizontal plane, this plurality of cavities being arranged in a star relative to the central cylindrical housing (202);
• a cavity substantially the same shape as the previous ones but whose interior volume is double and located in a plane different from the previous one. But it could be two separate cavities. These radial cavities are intended to receive one or two valves and bear the reference of the valve concerned assigned with an index (a).

Figure 3 shows the monobloc device (100) oriented so that the eye of the observer sees the plane upper of the housing intended to receive the pressure sensor (5) as well as, in the foreground, the set of radial star cavities (11a, 13a, 9a, 7a, 26a) and the double cavity (24-25) _a , the central housing (202) thus being partially hidden by all of these cavities.

FIG. 4, on the other hand, shows this monobloc device (100) oriented differently so that the eye of the observer sees, this time, in the background, all of the radial cavities and, in the foreground, the housing receiving the pressure sensor (5) and the base (600) carrying the piston (P) in fact constituted by the stacking of two parts (P1) and (P2) (see Figure 10).

The function of the holes (t₁, t₂ ... t _n ) illustrated in particular in FIG. 4 will also be defined later. The pipes are also made in the mass of the one-piece device (100). Their outings, which lead in variable volume chambers, bear the index (b) (Figures 8 and 9); their opposite outputs bear the indices (a) such as (C _26a , C _11a , C _13a , C _9a , C _25a , C _24a , C _7a ). There are also pipes having an area whose diameter is reduced, which can possibly perform the throttling function or simple connecting pipe between different elements. It will be noted that all the pipes are referenced (C), assigned an index corresponding to the valve which concerns them and the index (a) or (b) which has just been defined, and that the weakest pipes diameter carry the reference (L), or (R) in the case of a reference throttling affected by the index relating to the valve concerned. We find for example (R₈, R₁₀, L₂₄, L₂₂₀).

In the same spirit, FIG. 5 illustrates the one-piece device (100) already described by means of the two figures 3 and 4, but this time the observer sees it in an opposite position, the radial cavities are seen below. In this figure appear the two additional cavities (28a) and (28b) which have been, for reasons of clarity, deliberately omitted in Figures 3 and 4.

All these cavities are intended to receive the valves carrying in the circuit illustrated in FIG. 2, the reference corresponding to the cavity which is assigned to it but without the index (a). Thus the cavity (13a) receives the valve (13), the cavity (9a), the valve (9) and so on. The same is true for pipelines and restrictions.

The different valves (13, 11, 7, 9, 19, 28, 24, 25, 26) are embedded in their respective cavities, by example and without this being limiting in the manner illustrated by the two figures 6 and 7. By way of example and quite arbitrarily, the valve (13) of diameter (d) is shown in these figures. It is an in-line type electromagnetic valve, the two ends (e₁) and (e₂) of which are embedded in two grooves (g₁, g₂) provided for this purpose in the cavity. The hatching (PM) here symbolizes the material which is absent in FIGS. 3, 4 and 5, as has been said previously. Two O-rings (j₁) and (j₂) seal. A holding system (140a) pushes on the valve concerned, the valve (13) for example, of diameter (d) to keep it in its housing. This system (140a) can be integral with the flange (140) which holds the sensor (5) in place (Figure 10) and thus hold all the referenced valves (11, 9, 7 and 26).

Figure 6 is a longitudinal section and Figure 7 is a section transverse. This method of fixing the valves is not limiting. As has just been said, they are therefore in-line electromagnetic valves with reversible operation.

To complete the understanding, FIG. 8 illustrates a sectional view of this device (100), made at the level of the variable volume chamber (1) (element A). This section takes account of the presence of the material (M) absent in the preceding figures 3 to 5. We see that the section of the device (100) is square. We find there the cavity (26a) with its two outputs (C _26a ) and (C _26b ), then successively the cavity (11a) and its two outputs (C _11a ) and (C _11b ); the cavity (13) and its two outlets (C _13a ) and (C _13b ); the cavity (9a) and its two outlets (C _9a ) and (C _9b ); the cavity (7a) and its two outputs (C _7a ) and (C _7b ). There is also the cavity (28a) and the cavity (19a).

FIG. 9 illustrates a sectional view of the device (100) produced at the level of the variable volume chamber (23) (element B) where the double cavity (24,25) a _{is represented} with its two outputs (C _24a ; C _24b ) and (C _25a ; C _25b ) as well as the two cavities (28a) and (19a). All the valves and the pipes of the device (100) are connected to each other and to the various reservoirs as well as to the print head, in an exemplary embodiment that is in no way limitative, according to the diagram illustrated by means of FIG. 2.

According to the invention, such a device (100), as shown in Figure 10 which is a sectional view, is intended to cooperate with a reservoir block (300) as is now described. The device (100) therefore consists of a solid monolithic block in which we find all the cavities previously described. A pipe (Cp) communicates the pressure sensor (5) with the variable volume chamber (1). A flange (140) holds this sensor (5) in place and has profiles (140 _a ) serving as supports for the valves such as (26) intended to be embedded in the cavity (C26 _a ). The piston (P), as has been said previously, is constituted by the stacking of a base (600) and two parts (P2) of diameter (⌀₂) and (P1) of diameter (⌀₁). The first part (P1) delimits thanks to the installation of a first sealing membrane (m₁) and a flange (bd1), the variable volume chamber (1). The second part (P2), thanks to the installation of a second sealing membrane (m₂) and a second flange (bd2), delimits the variable volume chamber (23). A set of screws passing through the holes (t₁) to (t _n ) already mentioned maintains the two flanges (bd1) and (bd2) which pinch the two membranes (m₁) and (m₂) respectively.

The piston (P) is connected via the base (600) to a connecting rod (500) connected via an eccentric (3) supported by a bearing (181) to a motor (4) carried by an engine support (171). The one-piece reservoir block (300) is made, like the device (100), of insulating material and resistant to chemical attack, and is secured to this device (100) by any known means. The block (300) is disposed between the engine block (170) and the device (100) and comprises two compartments which perform the function of the tanks (17) and (18), and a passage (167) through which the connecting rod (500 ).

According to an important characteristic of the invention, the tank block (300) is positioned between the engine block (170) and the device (100). This arrangement makes it possible to obtain a maximum length of the connecting rod (500). Now, the greater this length, the smaller the angle that this connecting rod will guide at one of these ends by the eccentric (3) and at the other by the part (P1) of the piston (P), and the more precise the guiding of this piston (P) will be, all maintained in an area of isostatic mechanics with quite remarkable compactness qualities.

On the sides of the device (100) are arranged the cartridge holders (157) (only one is visible in this figure), the second being placed in front of the section of FIG. 10. These are the cartridge holders receiving the ink (15) and solvent (16) cartridges. According to a characteristic of the invention, these cartridges are removable and the ink is taken at a trocar (90) whose function is to penetrate a membrane provided for this purpose in the cartridge, pre-perforated EPT membrane using a very fine needle. Under these conditions, the penetration of the trocar (90) having been made without tearing, the sealing of the cartridge is automatically found when the user removes the latter.

According to another characteristic of the invention, the valves are arranged in a star, as has been seen previously, on the periphery of the variable volume chambers (1) and (23). Under these conditions, we obtain a dead volume of the chamber (1) as low as possible, which leads to a high compression ratio: if there is a little air in the chamber, we can still go up pressure.

In summary therefore, a device (100) according to the invention is extremely compact and comprises in its mass all the cavities and housings necessary for the installation of all the valves and of the piston delimiting the two variable volume chambers as well as the pressure sensor. It also includes in its mass the maximum number of pipes leading to these rooms and to the outside.

When all the valves, piston, cartridges and tanks are in place, the circuit is ready for operation. This operation has been described in the two patent and addition certificate applications cited above.

As has already been said previously, such a cell according to the invention allows access to multiple functions although its structure is extremely compact and its operation very simple. It finds its applications in particular in the field of inkjet printing, not only in the context of industrial marking, but also in that of office automation.

Claims (12)

1. A device for housing two chambers with variable volume (1, 23) and a capacitor (5) co-operating with a plurality of valves, the device providing smooth operation of an ink supply circuit for an ink jet (21) printhead (T) and the recovery of unused ink at the level of a recovery channel (22), the device having a cylindrical housing (202) in which a piston (P) may move, defining by means of two sealing membranes two chambers with variable volume inside the housing, the device being formed of a single solid mono-block part (100) made from a material that is resistant to chemical reactions, in which are compactly arranged:

   - the central cylindrical housing (202) with a first zone of a diameter of Φ2, defining the chambers with variable volumes (1, 23), inside the zones by means of two sealing membranes (m₁, m₂),

   - a plurality of cavities arranged radially in relation to the axis of the piston (P), for housing the valves, the first cavities (11a, 13a, 9a, 7a, 26a) being arranged in a star and having identical shape and volume with their bases located in a same horizontal plane, the second cavities (24a, 25a) being located in a second plane.

   - a housing for the capacitor (5).
2. A device in accordance with claim 1, characterised in that the piston (P) is formed by a stack comprising:

   - a base (600);

   - a first membrane (m₂) held by means of a strap (bd2);

   - a first part (P2) with a diameter of Φ2 capable of sliding in the Φ2 diameter zone of the cylindrical housing (202) to delineate the first chamber with variable volume (23);

   - a second membrane (m₁) held by means of a strap (bd1);

   - a second part (P1) with a diameter of Φ1 capable of sliding in the Φ1 zone of the cylindrical housing (202) to delineate the second chamber with variable volume (1).
3. A device in accordance with one of claims 1 and 2, characterised in that the housing for the capacitor (5) is contiguous with the Φ1 zone of the cylindrical housing (202).
4. A device in accordance with one of the previous claims, characterised in that these radial cavities have their outlet in channels providing communication between the ends of the valves and either the chambers with variable volumes (1, 23) or the other elements in the ink circuit.
5. A device in accordance with claim 4, characterised in that some of the channels have a zone whose diameter is reduced, forming a bottleneck.
6. A device in accordance with one of the previous claims, characterised in that the valves are electro-magnetically controlled valves of the in-line type.
7. A device in accordance with one of the previous claims, characterised in that the two ends of each of the valves are enclosed in two grooves (g1, g2), which are sealed by two joints (j1, j2).
8. A device in accordance with claim 1, characterised in that a strap (140) designed to hold the capacitor (5) in place comprises sections (140a) that are able to hold the bodies of the valves at the bottom of their cavities.
9. An ink supply circuit with a printhead, characterised in that it comprises a device (100) in accordance with one of the previous claims, designed to house two chambers with variable volume.
10. A supply circuit in accordance with claim 9, characterised in that the device (100) functions as a base for an ink reservoir block (300) having two ink reservoirs (17, 18) located between this device (100) and a motor block (170) and having a passage (167) crossed by a connecting rod (500), one end of which is connected to the base (600) of the piston (P) and the other end of which is connected to an eccentric (3) driven by the motor (4), this arrangement making it possible to use a connecting rod (500) of maximum length.
11. A supply circuit in accordance with one of claims 9 and 10, characterised in that it also comprises cartridge-holders (157) fixed to the device (100) designed for housing the ink cartridge (15) and the solvent cartridge (16).
12. A supply circuit in accordance with claim 11, characterised in that these cartridges (15) and (16) are movable, the intake of ink occurring at the level of a needle (90), whose function is to penetrate a pre-perforated membrane.

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