EP0321677A1 - 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 intended to receive 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. 8617385 filed on 12/10/86, supplemented by a request for Certificate of Addition No. 8712008 filed on 08/26/87, a fluid supply circuit of a inkjet print head equipped with a multi-function cell consisting in particular of two chambers whose volume varies as a function of the position of a single piston coupled to the same eccentric driven by the same motor. We find described in these two requests, all means: chambers, valves, restriction, tank, 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 easy to produce, simple and leading to an extremely compact final device.

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 and valve-restriction pairs to ensure the functions inherent in the proper functioning of a supply circuit in ink from an inkjet print head and ink recovery not used at the recovery gutter; device characterized in that it consists of a solid monobloc piece of material resistant to chemical attack, in which are made:
- on the one hand, a central cylindrical housing comprising two zones of diameter ⌀₁ and ⌀₂ in which a piston (P) can move, constituted by the stacking of two pieces of diameter ⌀₁ and ⌀₂ delimiting within these two zones, thanks to two waterproof membranes, the two variable volume chambers;
- on the other hand, a plurality of cavities intended to receive the valves;
- finally, 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 an alternative embodiment of an ink supply circuit of 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 as a function of 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 flow 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 Figure 1b and in the open position in the figure 1a, and vice versa for the valve (9). Finally, there is normally a restriction on the outlet pipes of each valve (8,10). These restrictions 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 (..P), the viscosity of the fluid during a pulse of fluid flow. These restrictions may 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 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-restriction pairs 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, there may also be mentioned the emptying of 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 the 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 organ located downstream 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 the 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 to maintain the viscosity of the ink used and recycled in the system. Maintaining the viscosity of the ink of the jet, is linked to an evaporation of the solvent during 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, results 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 tank (17), called the buffer tank, 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) linked parameter in particular at 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 motor rotor (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 indicated, the motor (4) rotates at constant speed cyclically, so that the two variable volume chambers (1) and (23) which are mechanically coupled, each generate their volume cyclically. This rotation cycle presents at each turn, a stop during the time necessary to the measurement of a static pressure, pressure measurement not influenced by the differential pressures induced by flow rates in restrictions (8), (10), (12) and (14). This allocated time allows the measurement of the 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 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 instruction;
• 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 illustrated firstly 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. It should however be noted that, when necessary for this understanding, the housing or the cavity shown bears 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 central cylindrical housing (202) comprising two zones of diameter (⌀₁) and (⌀₂), 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 located 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 device (100) in one piece oriented so that the eye of the observer sees the upper plane of the housing intended to receive the pressure sensor (5) and, in the foreground, all of the cavities radial star (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 with a smaller diameter than that of the previous ones, which can possibly fulfill the restriction function or simple connecting pipes 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 restriction, reference 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, for example and without this being limiting in the manner illustrated by the two figures 6 and 7. A As an 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 (M) here symbolizes the material being absent in FIGS. 3, 4 and 5, as has been said previously. Two O-rings (j₁) and (j₂) provide sealing. 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 into account 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) connects the pressure sensor (5) with the variable volume chamber (1). A flange (140) holds this sensor (5) in place and includes 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 reservoir 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). However, the greater this length, the smaller the angle that this 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 guidance of this piston (P), all of which is now in an area of isostatic mechanics with very 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 disposed in front of the section in 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, at 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 (13)

1. Device intended to receive two variable volume chambers (1,23) and a pressure sensor (5) cooperating with a plurality of valves and valve-restriction pairs to ensure the functions inherent in the proper functioning of a circuit of supplying ink to an ink jet printing head (T) and for recovering unused ink at the recovery gutter (22); device characterized in that it consists of a solid monobloc piece (100) of material resistant to chemical attack, in which are made:
- On the one hand, a central cylindrical housing (202) comprising two zones of diameter ⌀₁ and ⌀₂ in which a piston (P) can move, delimiting within these two zones, thanks to two waterproof membranes (m₁, m₂ ), the two variable volume chambers (1,23);
- on the other hand, a plurality of cavities intended to receive the valves;
- finally, a housing intended to receive the pressure sensor (5). 2. Device according to claim 1, characterized in that the piston (P) consists of the stack:
- a base (600);
- a membrane (m₂) pinched using a flange (bd2);
- a part (P2) of diameter ⌀₂ capable of sliding in the zone of diameter ⌀₂ of the housing (202) to delimit the variable volume chamber (23);
- a membrane (m₁) pinched using a flange (bd1);
- a part (P1) of diameter ⌀₁ capable of sliding in the zone of diameter ⌀₁ of the housing (202) to delimit the variable volume chamber (1). 3. Device according to one of claims 1 and 2, characterized in that the housing intended to receive the pressure sensor (5) is contiguous to the zone ⌀₁ of the housing (202). 4. Device according to one of the preceding claims, characterized in that these cavities are arranged radially relative to the axis of the piston (P), the first (11a, 13a, 9a, 7a, 26a) arranged in stars of identical shape and volume and whose bases are located in the same horizontal plane; the seconds (24a, 25a) located in a second plane. 5. Device (100) according to one of the preceding claims, characterized in that these radial cavities open onto pipes putting the ends of the valves in communication either with the chambers with variable volume (1,23), or with the other elements of the ink circuit. 6. Device (100) according to claim 5, characterized in that some of these pipes constitute restrictions. 7. Device according to one of the preceding claims, characterized in that the valves are in-line type electromagnetic valves. 8. Device according to claim 7, characterized in that the two ends of each of the electromagnetic valves are embedded in two grooves (g1, g2), the seal being provided by two seals (j1, j2). 9. Device according to one of claims 7 and 8, characterized in that a flange (140) intended to hold the pressure sensor (5) in place comprises profiles (140a) capable of holding the body of the electromagnetic valves at bottom of their cavity. 10. Ink supply circuit for a print head, characterized in that it comprises a device (100), according to one of the preceding claims, intended to receive two variable volume chambers. 11. Supply circuit according to claim 10, characterized in that the device (100) serves as a base for an ink tank block (300) comprising two ink tanks (17,18), placed between this device (100) and an engine block (170), and comprising 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 to an eccentric (3) driven by the motor (4), this architecture leading to obtaining a maximum length of the connecting rod (500). 12. Supply circuit according to one of claims 10 and 11, characterized in that it further comprises, made integral with the device (100), cartridge holders (157) intended to receive the ink cartridge ( 15) and the solvent cartridge (16). 13. Supply circuit according to claim 12, characterized in that these cartridges (15) and (16) are removable, the ink being taken at the level of a trocar (90) whose function is to penetrate a pre-perforated membrane.

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