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
  • B41J3/00—Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed
  • B41J3/407—Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed for marking on special material
  • B41J3/4073—Printing on three-dimensional objects not being in sheet or web form, e.g. spherical or cubic objects
• • 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

Definitions

• the present invention relates to a direct printing machine by spraying ink drops onto a support.
• the ink jet technique is known.
• piezoelectric ceramic print heads one chamber of which by deformation projects ink at the outlet of the nozzles onto a support.
• the projection of the ink can also be obtained, for certain types of ink, by heating generating the formation of a gas bubble whose expulsion causes the ink jet
• These techniques are associated with microprocessor-based control systems allowing to obtain the realization by ink projection of the desired image which can be, for example, a sign or an alphabetical letter or any representation
• These techniques are more particularly used in office automation equipment
• the relative displacements of the print head by ink jets and of the support to be printed are of small amplitude, which does not harm the quality of the print, the vacuum required at the output of the projection nozzles n not affected by small displacements
• the invention aims to produce a machine which can be used for direct printing, with corrosive inks, that is to say based on solvents or ultraviolet, on small or very large formats and on any type of support, in particular rigid, flat or in shape
• corrosive inks that is to say based on solvents or ultraviolet
• any type of support in particular rigid, flat or in shape
• Corrosive inks cannot be loaded into known dispensing cartridges of the HEWLETT PACKARD (registered trademark) or LEXMARK (registered trademark) type, it is necessary to design a specific ink supply system with devices making it possible to maintain a vacuum of 4 millibars at the level of the projection nozzles without pressure vanity detrimental to a good impression, regardless of the technical data according to which the relative movements between the heads and projection nozzles must be very rapid
• the heads and nozzles can be subjected to displacement speeds of 800 millimeters per second and to accelerations of 5000 millimeters per second squared, which generates a pressure variation at the level of the nozzles
• the nozzles operating in slight depression are capable, during displacement in dynamic operation, of sucking bubbles
• the present invention aims to provide a solution to this problem in the production of a direct printing machine.
• the machine according to the invention for direct printing operating by spraying ink drops onto a support, by one or more heads with projection nozzles, said machine being of the type with relative movements between the support to print and the projection heads, each head preferably being dedicated to a color or a tint is essentially characterized in that
• the head (s) is or are carried by a mobile assembly above the support to be printed along the three axes X, Y and Z orthogonal in space, - each of the heads is provided with a buffer tank carried by the mobile equipment
• the head (s) and their buffer tank are kept under vacuum and the buffer tanks are supplied with pressure from one or more stationary tanks
• the movable assembly cyclically brings the heads and the nozzles to a system for cleaning and maintaining the heads which, by suction, cleans the nozzles and the primers, by scraping removes the excess drops and which keeps the nozzles in good working order
• each on-board buffer tank is divided to reduce the amplitude of the waves produced by the movements of the tanks.
• FIG. 1 is a schematic plan view of a machine according to the invention
• FIG. 2 is a schematic representation of the hydraulic system of the machine according to the invention
• FIG. 3 is a schematic view of the buffer tanks with spray heads
• FIG. 4 and 5 are plan views and in section of the divider insert inserted into each of the tanks
• FIG. 6 shows in plan the cleaning and maintenance system of the spray heads and nozzles which is connected to the hydraulic circuit
• Figure 7 is a sectional view of the device shown in Figure 6
• FIG. 9 shows in section a buffer tank and an additional tank
• the machine comprises a rectangle table 1 comprising a planar, vertical plate, of rectangle shape on which is placed the support intended to receive the impression
• a transverse portal 2 is movable in the X direction on the table
• On the gantry 2 is mounted an on-board crew 3 mobile by any known means along the Y axis and the Z axis, the X, Y and Z axes being orthogonal in space
• the mobile crew can therefore move in any direction on table 1 and in height along Z with respect to it Its movements are controlled by a control and command unit comprising a microprocessor with the associated equipment.
• the position of the mobile equipment, in particular in height, in relation to the table is adjusted everywhere detection system of known type.
• the on-board crew 3 is shown in more detail in FIG. 2 with the hydraulic system.
• the high speed mobile on-board crew includes one or more buffer tanks 6
• each of them is connected by a line of line 7 to the stationary tank 4, which includes as many chambers and lines as there are buffer tanks
• each buffer tank 6 supplies a projection head and a single one
• the buffer tanks 6 are independent of each other and are removably mounted on the moving element. This arrangement, by allowing the individual replacement of each tank, facilitates the maintenance of the assembly.
• each tank 6 and associated projection head can now be assigned to a single color and to a single ink category this avoids the obligation of a complete cleaning of the tanks and heads before replacing the ink justified by problems of chemical and / or physical incompatibility which may exist between inks of different categories and / or in different colors
• the reference 8 indicates the connections of each of the heads which are supplied by a servo-controlled solenoid valve 9 downstream of each of the buffer tanks 6
• the distributors 9 are controlled individually by the control and command unit By the control of the solenoid valves is interrupted or established the communication between the buffer tanks and the associated projection heads and therefore the ink supply to the spray nozzles is established or interrupted.
• a servo-controlled solenoid valve 10 controlled by the control and command unit By controlling each of these solenoid valves is established or interrupted the communication between the associated reservoirs 4 and 6 and therefore the supply or not of the reservoir 6 with ink.
• the reservoir 6 is associated with a level detector capable of delivering two signals separate electrics, one of which is representative of a minimum level and the other of which is representative of a maximum level.
• This level detector is electrically connected to the monitoring and control unit to deliver the latter the minimum and maximum level signals.
• the buffer tanks 6 can be kept under vacuum by a common line 11 with means for putting under vacuum 12, said line being connected to a compressor 13. This means for putting under vacuum is advantageously constituted by a venturi effect device.
• Such a device comprises a first internal channel provided at one of its ends with a compressed air inlet mouth and at its other end with a compressed air outlet mouth.
• this internal channel opens radially the end of a second channel connected by its other end to the line 11. By passing an air flow in the first channel is created in the second a suction effect generating the depression.
• Line 11 is provided, between the compressor 13 and the venturi-effect device 12, with servo-control and adjustment means, such as filter, regulator and pressure gauge of known types and which are not described.
• servo-control and adjustment means such as filter, regulator and pressure gauge of known types and which are not described.
• a branch 14 connected to line 11 is connected, via a shutter
• the vacuum reservoir 17 is connected by a solenoid valve 19 to the system 5 for cleaning and maintenance of the ink spray nozzles .
• each buffer tank 6 is equipped with its own means of placing under vacuum.
• This means of placing under vacuum advantageously consists of a venturi effect device 12 like that previously described.
• the suction mouth of this venturi effect device is directly connected by its suction mouth to a through hole made in the upper wall of the buffer tank 6.
• each buffer tank 6 is supplied with ink by an additional tank 34 which is specific to it, the additional tank 34 being connected to the corresponding pipe 7 by the corresponding solenoid valve 10.
• This additional tank for example of cylindrical shape, comprises a bottom wall, an envelope wall standing vertically on the bottom wall and a shutter cover coming to rest on the horizontal upper bank of the envelope wall to close the opening that delimits said wall at this level
• the additional tank 34 receives the level detector device and is connected to the buffer tank 6 by a lower line 34a located below the minimum ink level and by an upper line 34b located above the ink level allowing the ink tank 6 to be supplied with ink and the pressure pressures to be balanced air in the two tanks
• the pipes 34a and 34b provide a rigid mechanical connection between the buffer tank 6 and the additional tank 34
• the lower part of the envelope wall of the additional tank is provided with a through hole which is connected the outlet outlet of the solenoid valve 10
• This additional tank is therefore supplied from below, this avoids during the ink supply, the formation of waves and shock waves, generating pressure vanations of the ink in the additional tank 34 and in the buffer tank 6
• the level detector is advantageously constituted by a float 35 and by a float position sensor 36, this sensor electrically connected to the control and command unit, being suitable to deliver to said unit a minimum level signal and a maximum level signal
• This detector is carried by the cover of the additional tank 34
• the projection heads operate in slight depression II is necessary for the regularity of the impression that this depression remains constant at around minus 4 millibars or undergo the least possible vanations, a variation of minus four to minus eight millibars being acceptable
• FIG. 3 shows a sectional view of a buffer tank among the four on-board buffer tanks 6
• Each buffer tank 6 is preferably a cylindrical volume, the top of which is closed off and the base 20 of which towards the electrodist ⁇ butor and the head is restricted. To this end, the bottom wall 21 of each buffer tank has a cylindrical volume of low height. and of smaller diameter than that of the tank with an outlet nozzle 22 In the cylindrical volume of each of the buffer tanks 6 is introduced a dividing device 23 which decomposes it into several small tanks and fulfills a wave breaker damping function
• the dividing device is a block of section corresponding to that of the internal volume of the buffer tank which is provided from top to bottom with parallel channels 24 defining as many small tanks
• the divider has at its base a recess 25 facilitating the circulation of the ink
• the buffer tanks 6 and additional, the dividers and the covers are made of suitable materials, resistant to the solvents of the inks used.
• FIG. 2 The device for cleaning the nozzle plates and for maintaining the nozzles connected to the compressor by the bypass 14 (FIG. 2) and shown diagrammatically in position in FIG. 1 is shown in detail in FIGS. 7 and 8 It consists of a plate 26 rectangle
• the reservations 27 are aligned and offset at an angle relative to their alignment axis
• the reservations 27 each receive a plate 28 made of a flexible material 29, for example made of silicone
• the plate 28 has two oblong parallel oblique lights
• a first short lumen 30 corresponds to a nozzle of the conduit 28
• the lumen 30 has two lips 31 of low height
• a second oblong lumen 32 corresponds to the conduit 29 This lumen 32 has a scraper lip 33
• This maintenance cycle makes it possible to clean the nozzles and nozzle plates and to prime the heads and the nozzles both while avoiding clogging thereof, for example by evaporation of the solvents.
• a prepolymé ⁇ sation is carried out for this purpose in the rear of the projection heads, the machine is equipped with a means capable of causing a polymerization of the ink affixed on the support, this means possibly consisting of a source of ultraviolet light radiation directed towards the support. Any other suitable means may be used.

Landscapes

• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Ink Jet (AREA)
• Coating Apparatus (AREA)
• Ink Jet Recording Methods And Recording Media Thereof (AREA)
• Particle Formation And Scattering Control In Inkjet Printers (AREA)
• Luminescent Compositions (AREA)
• Dot-Matrix Printers And Others (AREA)

Priority Applications (1)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9529565

Family Applications (1)

Country Status (11)

Cited By (1)

Families Citing this family (16)

Family Cites Families (11)

• 1998
  • 1998-08-10 FR FR9810250A patent/FR2782032B1/fr not_active Expired - Fee Related
• 1999
  • 1999-08-10 IL IL14134399A patent/IL141343A/xx not_active IP Right Cessation
  • 1999-08-10 AT AT99936715T patent/ATE240841T1/de not_active IP Right Cessation
  • 1999-08-10 AU AU51710/99A patent/AU5171099A/en not_active Abandoned
  • 1999-08-10 DE DE69908142T patent/DE69908142T2/de not_active Expired - Lifetime
  • 1999-08-10 WO PCT/FR1999/001963 patent/WO2000009339A1/fr active IP Right Grant
  • 1999-08-10 JP JP2000564818A patent/JP2002522279A/ja not_active Withdrawn
  • 1999-08-10 ES ES99936715T patent/ES2204148T3/es not_active Expired - Lifetime
  • 1999-08-10 EP EP99936715A patent/EP1105297B1/de not_active Expired - Lifetime
  • 1999-08-10 CN CN99811905A patent/CN1118376C/zh not_active Expired - Fee Related
  • 1999-08-10 US US09/762,653 patent/US6543877B1/en not_active Expired - Fee Related

Non-Patent Citations (1)

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