Classifications

• • 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
  • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
  • B41J2/01—Ink jet
  • B41J2/17—Ink jet characterised by ink handling
  • B41J2/175—Ink supply systems ; Circuit parts therefor
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T137/00—Fluid handling
  • Y10T137/2496—Self-proportioning or correlating systems
  • Y10T137/2499—Mixture condition maintaining or sensing
  • Y10T137/2506—By viscosity or consistency

Definitions

• the invention relates to an ink supply circuit for an ink jet print head. It also relates to any printer which is equipped with it.
• the orifice used for the formation of the jet is of reduced size (of the order of 75 mm) and it can happen that a dust comes to obstruct it. It is important, in this case to have a rapid means allowing the unclogging of this orifice.
• the printing qualities of such a printer are intimately linked to the speed of ejection of the ink from the orifice. The speed can be altered by a variation in ink pressure in front of the orifice, as well as by a variation in the viscosity of the ink. This can be due to a loss by evaporation of the solvent from the ink which is often very volatile.
• the object of the present invention is precisely to solve all these problems and relates to a circuit for supplying ink to a printer having a simple architecture and of very flexible operation which, with a minimum of components (two pumps and four solenoid valves) allows to obtain in particular a control of the pressure and the viscosity of the ink.
• the invention relates more precisely to a circuit for supplying ink to an ink jet print head, of the type comprising an ink tank, the bottom of which has a first outlet connected to a supply line. brought ink to a. pressurizing pump supplying the body of the print head through a supply line 20; an inlet connected to a discharge line through which the unused ink passes, taken from a recovery gutter and sucked in by means of a vacuum pump; and a second outlet connected to a mooring line connected to the vacuum pump; power circuit
• _ WIPO mentation characterized in that it further comprises a first auxiliary circuit mounted between the ink supply pipe and the supply pipe, and capable of measuring the pressure existing in the supply pipe.
• the invention also relates to such an ink supply circuit, further equipped with a second auxiliary circuit comprising a combination of solenoid valves capable of unblocking the ejection orifice of the drops of ink and the clear cut of the inkjet.
• It also relates to an ink supply circuit equipped with a third auxiliary circuit comprising means for measuring the viscosity of the ink.
• FIG. 1 schematically represents an embodiment of an ink supply circuit of a print head in accordance with 'invention.
• FIG. 2 schematically represents an exemplary embodiment of a device capable of measuring the viscosity of the ink, cooperating with the pressurization circuit of FIG. 1.
• FIG. 1 therefore schematically represents an ink supply circuit for an ink jet print head 10.
• a circuit essentially comprises a circuit ensuring the pressurization of the ink and a circuit ensuring a depressurization, intended to suck at the level of the recovery gutter 11 of the ink drops 100 not used.
• the ink is stored in a sealed reservoir 1 which conformé ⁇ to the invention comprises an internal partition 22 arranged parallel to the side walls of the reservoir, therefore perpendicular to the bottom (ab) of the latter.
• the low level 21 of the ink is detected by means of a sensor ⁇ 2. This ink is routed
• a pressure sensor 9 is interposed on the pipe 19. This. sensor 9 in an exemplary embodiment includes electrical contacts ⁇ ** and ⁇ 3 delimiting the pressure zone to be respected and a probe.
• This combination makes it possible to obtain a signal and to use an associated electronic device (not shown) which permanently controls the speed of the motor 4 so that the pressure in the pipes 19 and 20 retains a fixed and determined value whatever the variation of the parameters which govern it such as, for example, internal leaks at the pump or improper calibration of the leak 17.
• This first auxiliary circuit according to the invention and referenced R2 therefore ensures a stable pressure.
• a vacuum circuit cooperates with the pressurization circuit described above, the function of which is to recover at the level of the drop.
• a so-called vacuum pump 7 of the same type as the so-called pressurizing pump 5 is used. These two pumps 5 and 7 can be connected to the same motor 4.
• the pump 7 is a volume pump which normally generates a flow of liquid. It may for example be a gear pump.
• the ink drops 100, collected at the level of the gutter 11 are sucked through a so-called suction pipe 27. This result can only be obtained if the pump 7 is capable of generating an air flow and this from starting the system, when the suction line 27 is still empty of ink.
• This type of pump may have internal leaks. In the case of liquids these are negligible, but they are predominant with gases.
• an extension 26 plugged in A is intended to be connected if necessary to a device for measuring the viscosity ink as will be described later.
• This operation of the pump 7 takes place and therefore this depression is created, even if the pipe 27 and its extension 26 contain air in high proportion.
• the pump 7, permanently wetted with ink from the reservoir 1 through the leak 25 therefore sucks in air and recovered ink from the recovery gutter I I.
• the ink and the air is discharged to the sealed tank 1 by a so-called discharge pipe 28 and according to a characteristic of the invention this pipe 28 is connected to a rigid pipe 24 and perpendicular to the bottom (a, b) of the reservoir 1, located inside the compartment C delimited by the partition 22.
• the line 27 reaches the maximum depression that the pump 7 can generate. If the printer is stopped at this time, the line 27 will suck ink from the reservoir 1 which can only be replaced by air from the orifice 36.
• the non-return valve 47 in this case prevents the "return of bubbling liquid in the ink, which would imply a complete purging of the circuits.
• the circuit R2 for connection to the print head is now described.
• the body 10 of this print head supporting the orifice 41 creating the jet 100 can be pressurized at the request of the operator by a solenoid valve 13 connected to the head by a pipe 47.
• a solenoid valve 12 called purge connects the pipe 27 of the vacuum system to a pipe 48 which is at the same pressure as that of the body 10.
• the solenoid valve 13 In normal operation the solenoid valve 13 is in the open position and the solenoid valve 12 in the closed position.
• the latter performs three essential functions. Firstly, after a prolonged shutdown of the machine, the line 20, especially if it is long, may contain degraded ink. It may be useful in this case to replace it with fresh ink coming from the reservoir 1. The flow of the ink jet, cannot allow this operation to be done quickly while the opening of the solenoid valve 12 allows to create a significant flow in the line 20, and in the body 10 and therefore to refresh the ink quickly.
• this solenoid valve 12 allows an easy uncorking of the orifice 41, if it is for example closed by a dust.
• the solenoid valve 13 is closed for this and the solenoid valve 12 is opened so that the body 10 is then in depression. Under these conditions it is possible to suck solvent through the orifice 41 and thus expel the dust towards the pipe 48.
• the function of the solenoid valve 12 is to ensure, during the procedure for stopping the printer, a clean stop of the ink jet.
• the pipes 47 and 48 which are under pressure, swell slightly, especially if they are made of plastic and of great lengths.
• the solenoid valve 13 is closed to cut the jet, the persistence of pressure in 47 and 48 means that the jet cannot be cut immediately, given its low flow rate. This inevitably leads to pollution of the environment of the jet, which is to be avoided.
• the original architecture of the ink supply circuit in accordance with the invention overcomes these drawbacks. When you want to cut the jet, you open the solenoid valve 12 shortly before the closing of the solenoid valve 13.
• FIG. 2 schematically represents an example of a device capable of measuring the viscosity of the ink, called a viscometer V in the following description cooperating, in accordance with the invention with the pressurization circuit described previously by means of FIG. 1. It is a third circuit R3.
• This viscometer (V) essentially consists of a container
• This container 14 has three electrodes
• the ink is conductive.
• the ink will be above the low level (x) when the electrodes 32 and 33 are in short circuit; on the other hand the ink will be at the high level (y) when the electrodes (32) and (34) are short-circuited.
• the flow of ink through line 30 makes it possible to fill the container 14, the pressure balances at the surfaces of liquid 37 in the compartment C and 40 in the container 14 is achieved by means of a pipe 35 containing only l air and solvent vapors.
• a solenoid valve 15 cooperates with the viscometer (V) as described below.
• the solenoid valve 15 connects the bottom of the container 14 with point A, that is to say with the pipe
• the filling time (tr) increases. As soon as it reaches a setpoint considered as a limit, the viscosity is then corrected by adding solvent.
• a solenoid valve 16 is provided to connect a reserve 2 containing pure solvent with point A, that is to say the line 26 which is in depression. This solvent is then sent
• An ink jet printer equipped with an ink supply circuit according to the invention makes it possible to solve the main problems posed by this type of machine, namely in particular: - obtaining a stable pressure;
• the invention applies to any type of inkjet printer.

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• Ink Jet (AREA)

Applications Claiming Priority (2)

Publications (2)

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ID=9293186

Family Applications (1)

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• 1983
  • 1983-10-13 FR FR8316440A patent/FR2553341B1/fr not_active Expired
• 1984
  • 1984-10-11 DE DE8484903715T patent/DE3470693D1/de not_active Expired
  • 1984-10-11 AU AU35052/84A patent/AU581631B2/en not_active Ceased
  • 1984-10-11 WO PCT/FR1984/000228 patent/WO1985001696A1/fr active IP Right Grant
  • 1984-10-11 EP EP19840903715 patent/EP0160019B1/de not_active Expired
  • 1984-10-11 US US06/740,049 patent/US4628329A/en not_active Expired - Lifetime
  • 1984-10-11 JP JP59503789A patent/JPS61500162A/ja active Granted
  • 1984-10-12 IT IT6801284A patent/IT1179769B/it active
  • 1984-10-12 IT IT5391984U patent/IT8453919V0/it unknown
  • 1984-10-12 CA CA000465301A patent/CA1250486A/fr not_active Expired

Non-Patent Citations (1)

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