A continuous inkjet printer is provided comprising an ink supply system, a droplet generator configured to receive ink from the ink supply system and to produce a jet of ink for printing, a gutter configured to receive parts of the jet that are not required for printing, a gutter line connected to the gutter and configured to return unprinted ink to the ink supply system, a suction system comprising a Venturi having a suction port configured to apply a suction force to the gutter line, and a gutter flow rate control system configured to control a rate of flow of fluid along the gutter line based on temperature.
B41J 2/02 - Ink jet characterised by the jet generation process generating a continuous ink jet
B41J 2/045 - Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
A filter module for filtering ink. The filter module comprising: a filter housing defining: a filter chamber; an inlet port; a first outlet port; and a second outlet port. The filter module further comprising a first filter element, comprising a first filter media, disposed in the filter chamber. The filter housing is configured to define a first filtrate path from the inlet port to the first outlet port via the first filter element, and a second path from the first inlet port across an outer surface of the first filter element to the second outlet port. When in use, the first outlet port and the second outlet port are arranged vertically above the inlet port.
An ink tank for an inkjet printer. The ink tank comprising a tank floor defining a bottom surface of the tank and tank walls defining sides of the tank during normal use. The tank comprising: a tank bottom defining a lowest point within the tank; a bulk region configured to store a majority of the ink within the ink tank, the tank floor within the bulk region being horizontal or sloping towards the tank bottom during normal use; and a mixing region between the tank bottom and the bulk region partially enclosed by a mixing region tank wall.
A system (93) monitors the break-up phase of an electrostatic deflection continuous ink jet printer to identify phase instability likely to be caused by a partial blockage of the jet-forming device (17). It ignores alternations between adjacent phase positions and brief unrepeated periods of phase disruption. Preferably it ignores phase changes caused by changes in other operational parameters of the printer, such as variations in ink pressure. Monitoring may be done in the printer (99) or in an external system (93), (95).
The current at a deflection electrode 23, 25 of an electrostatic deflection continuous inkjet printer 127 is monitored. If the current reaches a level higher than normal for a clean print head but below the current required to trigger an automatic shutdown, a warning is generated. The warning indicates that an automatic shutdown is likely to follow unless the print head is cleaned. This allows the operator to shut the printer down in a planned manner for cleaning. The warning may be provided at the printer 127 or it may be provided by an external system 121, 129 which allows personnel who are not at the printer to be alerted. The monitoring may be done by the printer or information about the deflection electrode current may be provided to an external system 121, 129 that performs the monitoring.
A continuous inkjet printer is provided comprising an ink supply system, a droplet generator configured to receive ink from the ink supply system and to produce a jet of ink for printing, a gutter configured to receive parts of the jet that are not required for printing, a gutter line connected to the gutter and configured to return unprinted ink to the ink supply system, a suction system comprising a Venturi having a suction port configured to apply a suction force to the gutter line, and a gutter flow rate control system configured to control a rate of flow of fluid along the gutter line based on temperature.
The print head cover (83) of an electrostatic deflection inkjet printer is made of a material having an electrical surface resistivity of no more than 1012 ohms per square or an electrical volume resistivity of no more than 109 ohm metres and is electrically connected to an earth line (93, 97). This prevents build-up of electric charge on the cover (83). The resistance from the surface of the cover (83) to a place where a cover earth line (93) joins a signal earth line (97) or enters the umbilical (7) is at least 16000 times the resistance from that place to earth. This prevents an electrostatic discharge to the cover (83) disrupting the electronic circuits. The high resistance earth connection for the cover (83) avoids the need for an earthing wire braid in the umbilical (7). The cover (83) may be moulded from an antistatic or static dissipative material.
A system (93) monitors the break-up phase of an electrostatic deflection continuous ink jet printer to identify phase instability likely to be caused by a partial blockage of the jet-forming device (17). It ignores alternations between adjacent phase positions and brief unrepeated periods of phase disruption. Preferably it ignores phase changes caused by changes in other operational parameters of the printer, such as variations in ink pressure. Monitoring may be done in the printer (99) or in an external system (93), (95).
B41J 2/045 - Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
9.
INK JET PRINTER AND METHOD OF MONITORING AN INK JET PRINTER
The current at a deflection electrode 23, 25 of an electrostatic deflection continuous inkjet printer 127 is monitored. If the current reaches a level higher than normal for a clean print head but below the current required to trigger an automatic shutdown, a warning is generated. The warning indicates that an automatic shutdown is likely to follow unless the print head is cleaned. This allows the operator to shut the printer down in a planned manner for cleaning. The warning may be provided at the printer 127 or it may be provided by an external system 121, 129 which allows personnel who are not at the printer to be alerted. The monitoring may be done by the printer or information about the deflection electrode current may be provided to an external system 121, 129 that performs the monitoring.
A low conductivity layer (83) is provided over an electrically conductive core (85) of the charge electrode (21) of an electrostatic deflection continuous ink jet printer at all of the exposed part of the charge electrode (21). The low conductivity layer (83) is at least 0.1 mm thick and has a volume electrical resistivity of 104 to 109 ohm metres. The low conductivity layer (83) provides at least partial electrical safety in case an operator touches the charge (electrode 21) while the charge electrode voltage is applied, but is also capable of dissipating any electrostatic charges that might otherwise accumulate on the surface of the charge electrode (21).
The print head cover (83) of an electrostatic deflection inkjet printer is made of a material having an electrical surface resistivity of no more than 1012ohms per square or an electrical volume resistivity of no more than 109 ohm metres and is electrically connected to an earth line (93, 97). This prevents build-up of electric charge on the cover (83). The resistance from the surface of the cover (83) to a place where a cover earth line (93) joins a signal earth line (97) or enters the umbilical (7) is at least 16000 times the resistance from that place to earth. This prevents an electrostatic discharge to the cover (83) disrupting the electronic circuits. The high resistance earth connection for the cover (83) avoids the need for an earthing wire braid in the umbilical (7). The cover (83) may be moulded from an antistatic or static dissipative material.
In a continuous ink jet printer for use with pigmented ink, the entrance to the ink path (81), (35) from the interior of the ink tank (27) to the ink pump (31) is made up of a plurality of small inlet openings, which may be provided by nozzles 85 formed in a shroud 83 that fits around an ink filter (33) in the ink tank (27). The openings are provided at the bottom of the ink tank (27), close to the floor, and face parallel to the floor or at least partially towards it. If the ink pump (31) is driven in reverse, any ink in the ink path is driven at speed out through the inlet openings into the interior of the ink tank (27), followed by air. This tends to disperse pigment that may have settled to the bottom on the ink tank (27).
A continuous inkjet printer has an ink circuit comprising an ink tank, an ink pump and a Venture suction device. The Venturi is used to suck an extra solvent or ink as required. However, if the ink tank is empty, no ink can be pumped through the Venture and so it will not develop suction and thus, cannot be used to suck in an initial supply of ink to an empty tank. A removable ink container may be connected to the ink tank or elsewhere in the ink circuit, for example, between the Venturi outlet and the pump inlet. Compressing the ink container manually will force ink into the ink circuit. When enough ink has been added, the pump will drive ink through the Venturi and suction will be generated.
A non-contact printer controls the sensitivity of sensors provided upstream of a print head, to detect the approach of an object. In a calibration operation to set the sensitivity level of the sensors before a printing operation, the printer displays instructions to guide the operator and adjusts the sensor sensitivity to find detection threshold levels for a background (object absent) condition and when the object is present. The calibration results may be stored in association with data identifying the conveyor and the type of object used in the calibration operation. If the same conveyor and/or object type is used again in a later printing operation, the sensitivity level of the sensors can be set using the stored calibration results so that a further calibration operation is not necessary.
B41J 2/045 - Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
B41J 11/00 - Devices or arrangements for supporting or handling copy material in sheet or web form
B41J 3/46 - Printing mechanisms combined with apparatus providing a visual indication
B41J 3/28 - Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed for printing downwardly on flat surfaces, e.g. of books, drawings, boxes
B41J 3/407 - Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed for marking on special material
Either during message selection in an industrial printer (e.g. ink jet or laser marking) for printing onto objects carried past it on a conveyor, or during printing, or both, a printer displays an image associated with the message proposed for printing or being printed. The image may be a picture (e.g. a photograph) of the object on which the message should be printed or the intended customer/end user or the intended use of the object on which the message should be printed. Since a human operator can usually identify an object or intended customer/use more quickly and accurately from a picture than from text, this reduces errors in message selection and/or helps the detection of an incorrect message during printing. The image may be displayed with the associated message or without it.
B41J 3/407 - Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed for marking on special material
B41J 5/00 - Devices or arrangements for controlling character selection
B41J 3/46 - Printing mechanisms combined with apparatus providing a visual indication
B65B 61/02 - Auxiliary devices, not otherwise provided for, for operating on sheets, blanks, webs, binding material, containers or packages for perforating, scoring, or applying code or date marks on material prior to packaging
H04N 1/00 - Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmissionDetails thereof
H04N 1/32 - Circuits or arrangements for control or supervision between transmitter and receiver
09 - Scientific and electric apparatus and instruments
42 - Scientific, technological and industrial services, research and design
Goods & Services
Gateways for the Internet of Things (IoT); computer software for use in relation to the Internet of Things (IoT); computer software and downloadable computer software; computer software for networking and system management; computing infrastructure and platforms for the purpose of connecting, operating and managing Internet of Things (IoT) devices; Interfaces for computers; not including any goods relating to the provision of internet exchange points to ISPs or network providers, or the interconnection of internet networks for ISPs or network providers. Cloud computing; providing non-downloadable platforms and software; software as a service (SaaS) services; providing temporary use of non-downloadable cloud-based software for connecting, operating and managing networked devices in the Internet of Things (IoT); providing online non-downloadable software; providing online non-downloadable software for use with printing, marking and coding apparatus and machines; not including any services relating to the provision of internet exchange points to ISPs or network providers, or the interconnection of internet networks for ISPs or network providers.
In a continuous ink jet printer for use with pigmented ink, the entrance to the ink path (81), (35) from the interior of the ink tank (27) to the ink pump (31) is made up of a plurality of small inlet openings, which may be provided by nozzles 85 formed in a shroud 83 that fits around an ink filter (33) in the ink tank (27). The openings are provided at the bottom of the ink tank (27), close to the floor, and face parallel to the floor or at least partially towards it. If the ink pump (31) is driven in reverse, any ink in the ink path is driven at speed out through the inlet openings into the interior of the ink tank (27), followed by air. This tends to disperse pigment that may have settled to the bottom on the ink tank (27).
An electrostatic deflection ink jet printer has a main printer body (1) separated by a vapour barrier (67) into an electrical region and a fluid region. Electrically operated valves (39, 41, 45, 51, 57) are provided in the fluid region. Control circuitry (69) for deciding when to operate the valves is provided in the electrical region. Valve drive circuitry (65), for generating drive currents for the valves, is provided in the fluid region and is in data communication with the control circuitry (69) via wiring (preferably comprising a serial data bus) that passes through the vapour barrier (67). This reduces the number of electrical connections that need to pass through the vapour barrier. Preferably a circuit carrier (85) for the valve drive circuitry is mounted on a valve block (63) for the valves, and an electrically insulating material (109) covers the circuit carrier (85). The electrically insulating material (109) may extend partially or wholly around the valve block (63).
A continuous ink jet printer has an ink circuit comprising an ink tank (27), an ink pump (31) and a Venturi suction device (35), (49). The Venturi (49) is used to suck in extra solvent or ink as required. However, if the ink tank (27) is empty, no ink can be pumped through the Venturi (49) and so it will not develop suction. Therefore the Venturi (49) cannot be used to suck in an initial supply of ink to an empty tank. This problem is overcome by connecting a removable ink container (63) to the ink tank (27) or elsewhere in the ink circuit (preferably between the Venturi outlet and the pump inlet), and then compressing the ink container manually to force ink into the ink circuit. When enough ink has been added, the pump (31) will drive ink through the Venturi (49) and suction will be generated.
A non-contact printer controls the sensitivity of sensors (31) provided upstream of a print head (5), to detect the approach of an object (11) to be printed onto. In a calibration operation to set the sensitivity level of the sensors before a printing operation, the printer displays instructions to guide the operator and adjusts the sensor sensitivity to find detection threshold levels for a background (object absent) condition and when the object is present. The calibration results can be stored in association with data identifying the conveyor (13) and the type of object used in the calibration operation. If the same conveyor and/or object type is used again in a later printing operation, the sensitivity level of the sensors can be set using the stored calibration results so that a further calibration operation is not necessary.
B41J 3/407 - Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed for marking on special material
B41J 11/00 - Devices or arrangements for supporting or handling copy material in sheet or web form
B41J 3/28 - Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed for printing downwardly on flat surfaces, e.g. of books, drawings, boxes
B41J 3/46 - Printing mechanisms combined with apparatus providing a visual indication
Either during message selection in an industrial printer (e.g. ink jet or laser marking) for printing onto objects (27) carried past it on a conveyor (29), or during printing, or both, the printer displays an image (51, 53) associated with the message proposed for printing or being printed. The image may be a picture (e.g. a photograph) of the object (27) on which the message should be printed or the intended customer/end user or the intended use of the object on which the message should be printed. Since a human operator can usually identify an object or intended customer/use more quickly and accurately from a picture than from text, this reduces errors in message selection and/or helps the detection of an incorrect message during printing. The image may be displayed with the associated message or without it.
A cap 13, 15, for the print face 9 of a drop-on-demand ink jet printer moves between a closed position, in which it covers the print nozzles on the print face 9, and an open position in which the print nozzles are uncovered, without requiring movement of the print face 9. In the open position, the cap is recessed relative to the front surface 21 of the printhead. For at least part of the movement of the cap, it is further forward than the print face 9, so that it does not slide across and damage the print nozzles. The drop-on-demand ink jet printer may be used to print onto objects 3 conveyed past it, for example on a packing line. The cap 13, 15, does not obstruct the path of the objects 3 even if they pass very close (e.g. 0.5 mm) to the print face 9 because its uncapped position is further back than the front surface 21 of the printhead.
09 - Scientific and electric apparatus and instruments
Goods & Services
Pigments, printers' pastes, printing ink; paints, varnishes, lacquers, resins, colourants, dye stuffs. Printing machines, conveyors being parts of printers and printing machines, air compressors, control mechanisms for printing machines, compressors and conveyors being parts of printing machines; filters for cleaning and cooling air (for printing and coding machines), ink spray heads for printing machines; printing machines; ink jet printing machines; printing apparatus; mechanisms for performing operational steps in printing machines; parts and fittings for all of the aforesaid goods. Lasers, laser beam printers, laser operated marking and identifying apparatus; printers; ink jet printers; control apparatus, conveyors being parts of printers, compressors being parts of printers; control apparatus for performing operational steps in printing machines; software for performing operational steps in printing machines; parts and fittings for all of the aforesaid goods.
A cap 13, 15, for the print face 9 of a drop-on-demand ink jet printer moves between a closed position, in which it covers the print nozzles on the print face 9, and an open position in which the print nozzles are uncovered, without requiring movement of the print face 9. In the open position, the cap is recessed relative to the front surface 21 of the printhead. For at least part of the movement of the cap, it is further forward than the print face 9, so that it does not slide across and damage the print nozzles. The drop-on-demand ink jet printer may be used to print onto objects 3 conveyed past it, for example on a packing line. The cap 13, 15, does not obstruct the path of the objects 3 even if they pass very close (e.g. 0.5 mm) to the print face 9 because its uncapped position is further back than the front surface 21 of the printhead.
B41J 2/165 - Prevention of nozzle clogging, e.g. cleaning, capping or moistening for nozzles
B41J 3/407 - Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed for marking on special material
A cap (13), (15), for the print face (9) of a drop-on-demand ink jet printer moves between a closed position, in which it covers the print nozzles on the print face (9), and an open position in which the print nozzles are uncovered, without requiring movement of the print face (9). In the open position, the cap is recessed relative to the front surface (2)1 of the printhead. For at least part of the movement of the cap, it is further forward than the print face (9), so that it does not slide across and damage the print nozzles. The drop-on-demand ink jet printer may be used to print onto objects 3 conveyed past it, for example on a packing line. The cap (13), (15), does not obstruct the path of the objects (3) even if they pass very close (e.g. 0.5 mm) to the print face 9 because its uncapped position is further back than the front surface (21) of the printhead.
B41J 2/165 - Prevention of nozzle clogging, e.g. cleaning, capping or moistening for nozzles
B41J 3/407 - Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed for marking on special material
b) for recirculating back to the printhead (25) at least some of the air that has been sucked down the gutter line (17). Preferably the relative proportions of vented air and recirculated air can be varied, so as to reduce solvent loss during normal operation but allow increased solvent loss if the ink is over-dilute. Preferably the air recirculated to the printhead is connected directly into the flow path from the gutter orifice to the source of gutter suction, without opening into the space containing the ink jet. This reduces the tendency of solvent in the recirculated air condense on the printhead electrodes.
An ink/air separator for an ink jet printer has one or more plates 77, 79, 81, 83 over which an ink/air mixture can spread. Preferably there is more than one plate, and the mixture overflows from one plate to the next. Preferably adjacent plates are spaced so that as the mixture passes between two plates it contacts the surface above it as well as the surface below it. The plates may be separated by a gap of 10 mm or less, e.g. a gap of 2 mm to 5 mm, where they overlap Preferably some or all of the plate surfaces contacted by the mixture are roughened. Interaction between the ink/air mixture and the plate surface tends to slow the flow of very small air bubbles and encourage them to accumulate and/or merge, so that they separate from the ink more quickly than individual small bubbles. The ink/air separator may be connected in the path of unused ink returned from the gutter 27 of a continuous ink jet printer to an ink tank 39, or may be placed inside the ink tank 39.
09 - Scientific and electric apparatus and instruments
Goods & Services
Pigments, printers' pastes, printing ink; paints, varnishes,
lacquers, resins, colourants, dyestuffs. Printing machines, conveyors being parts of printing
machines, air compressors, control mechanisms for printing
machines, compressors and conveyors being parts of printing
machines; filters for cleaning and cooling air (for printing
and coding machines), ink spray heads for printing machines;
printing machines; ink jet printing machines; control
apparatus and mechanisms for printing machines; parts and
fittings for all of the aforesaid goods. Lasers, laser beam printers, laser operated apparatus for
applying marks or identifying signs to objects; printers;
ink jet printers; control apparatus and mechanisms for
printers; parts and fittings for all of the aforesaid goods.
09 - Scientific and electric apparatus and instruments
Goods & Services
Pigments, printers' pastes, printing ink; paints, varnishes,
lacquers, resins, colourants, dyestuffs. Printing machines, conveyors being parts of printing
machines, air compressors, control mechanisms for printing
machines, compressors and conveyors being parts of printing
machines; filters for cleaning and cooling air (for printing
and coding machines), ink spray heads for printing machines;
printing machines; ink jet printing machines; control
apparatus and mechanisms for printing machines; parts and
fittings for all of the aforesaid goods. Lasers, laser beam printers, laser operated apparatus for
applying marks or identifying signs to objects; printers;
ink jet printers; control apparatus and mechanisms for
printers; parts and fittings for all of the aforesaid goods.
An ink/air separator for an ink jet printer has one or more plates (77, 79, 81, 83) over which an ink/air mixture can spread. Preferably there is more than one plate, and the mixture overflows from one plate to the next. Preferably adjacent plates are spaced so that as the mixture passes between two plates it contacts the surface above it as well as the surface below it. The plates may be separated by a gap of 10 mm or less, e.g. a gap of 2 mm to 5 mm, where they overlap Preferably some or all of the plate surfaces contacted by the mixture are roughened. Interaction between the ink/air mixture and the plate surface tends to slow the flow of very small air bubbles and encourage them to accumulate and/or merge, so that they separate from the ink more quickly than individual small bubbles. The ink/air separator may be connected in the path of unused ink returned from the gutter (27) of a continuous ink jet printer to an ink tank (39), or may be placed inside the ink tank (39).
09 - Scientific and electric apparatus and instruments
Goods & Services
Printers; printing machines; ink jet printing machines; printing apparatus; control apparatus, mechanisms and processes for performing operational steps in printing machines; parts and fittings for all of the aforesaid goods. Printers; printing machines; ink jet printers; printing apparatus; control apparatus, mechanisms and processes for performing operational steps in printing machines; printer interfaces; computer interfaces for printers; computer interface software for printers; computer software for use with printers; user interface software for use with printers; printer interfaces accessible via the internet; computer interfaces for printers accessible via the internet; printer web interfaces; parts and fittings for all of the aforesaid goods; not including any goods relating to the provision of internet exchange points to ISPs or network providers, or the interconnection of internet networks for ISPs or network providers.
09 - Scientific and electric apparatus and instruments
Goods & Services
Pigments, printers' pastes, printing ink; paints, varnishes, lacquers, resins, colourants, dye stuffs. Printing machines, conveyors being parts of printers and printing machines, air compressors, control mechanisms for printing machines, compressors and conveyors being parts of printing machines; filters for cleaning and cooling air (for printing and coding machines), ink spray heads for printing machines; printing machines; ink jet printing machines; printing apparatus; mechanisms for performing operational steps in printing machines; parts and fittings for all of the aforesaid goods. Lasers, laser beam printers, laser operated marking and identifying apparatus; printers; printing machines; ink jet printers; control apparatus, conveyors being parts of printers, compressors being parts of printers; control apparatus for performing operational steps in printing machines; software for performing operational steps in printing machines; parts and fittings for all of the aforesaid goods.
09 - Scientific and electric apparatus and instruments
Goods & Services
Pigments, printers' pastes, printing ink; paints, varnishes, lacquers, resins, colourants, dye stuffs. Printing machines, conveyors being parts of printers and printing machines, air compressors, control mechanisms for printing machines, compressors and conveyors being parts of printing machines; filters for cleaning and cooling air (for printing and coding machines), ink spray heads for printing machines; printing machines; ink jet printing machines; printing apparatus; mechanisms for performing operational steps in printing machines; parts and fittings for all of the aforesaid goods. Lasers, laser beam printers, laser operated marking and identifying apparatus; printers; printing machines; ink jet printers; control apparatus, conveyors being parts of printers, compressors being parts of printers; control apparatus for performing operational steps in printing machines; software for performing operational steps in printing machines; parts and fittings for all of the aforesaid goods.
36.
Inkjet printer and flow restriction system therefor
A gutter line of a continuous inkjet printer which includes a variable flow restrictor fitted into the gutter line, and a pressure transducer for measuring the pressure in the gutter line downstream of the variable flow restrictor, where the variable flow restrictor is controlled in response to the output of the pressure transducer to maintain a downstream pressure substantially constant. Airflow along the gutter line has a lower flow resistance than a slug of ink. Accordingly, the system responds dynamically to restrict the flow of air along the gutter line when no ink is passing along it, thereby reducing the volume of air sucked along the gutter line while maintaining adequate suction to reliably clear ink away from the gutter so that the amount of solvent lost from the ink is reduced during operation of an inkjet printer.
A continuous ink jet printer comprising an ink gun for forming an ink jet; an arrangement of electrodes for trapping electric charges on ink drops of the ink jet and for creating an electrostatic field for deflecting drops carrying trapped electric charges; and a gutter having an ink-receiving orifice for receiving ink drops of the ink jet which are not used for printing; a gutter flow path for flow of ink from the ink-receiving orifice of the gutter, through and away from the gutter; an air recirculation line for conveying at least some of any air that has passed with the ink along at least a part of the gutter flow path so as to re-enter the gutter flow path either through the ink-receiving orifice or through a connection into the gutter flow path downstream of the ink-receiving orifice; and a vent for venting at least some of the air that has passed with the ink along at least a part of the gutter flow path so as not to re-enter the gutter flow path.
A system for adjusting the flow of fluid along the gutter line of a continuous inkjet printer includes a variable flow restrictor (1) fitted into the gutter line (3), and a pressure transducer (5) for measuring the pressure in the gutter line (3) downstream of the variable flow restrictor (1). The variable flow restrictor (1) is controlled in response to the output of the pressure transducer (5) in order to maintain the downstream pressure substantially constant. Since airflow along the gutter line (3) has a lower flow resistance than a slug of ink, the variable flow restrictor (1) will apply a greater flow restriction to the gutter (line 3), in order to maintain constant pressure at the pressure transducer (5), when there is only air in the gutter line (3) as compared with when a slug of ink passes along the gutter line (3). Accordingly, the system responds dynamically to restrict the flow of air along the gutter line (3) when no ink is passing along it, thereby reducing the volume of air sucked along the gutter line (3) while maintaining adequate suction to clear ink reliably away from the gutter (103). This reduction in the amount of air passing along the gutter line (3) can reduce the amount of solvent lost from the ink during operation of an inkjet printer.
A continuous ink jet printer has a line (69a) for venting at least some of the air that has been sucked along the gutter line (17), and a line (69b) for recirculating back to the printhead (25) at least some of the air that has been sucked down the gutter line (17). Preferably the relative proportions of vented air and recirculated air can be varied, so as to reduce solvent loss during normal operation but allow increased solvent loss if the ink is over-dilute. Preferably the air recirculated to the printhead is connected directly into the flow path from the gutter orifice to the source of gutter suction, without opening into the space containing the ink jet. This reduces the tendency of solvent in the recirculated air condense on the printhead electrodes.
09 - Scientific and electric apparatus and instruments
Goods & Services
Pigments, printers' pastes, printing ink. Printing machines, conveyors being parts of printers and printing machines, air compressors, control mechanisms for printing machines, compressors and conveyors being parts of printers and printing machines; filters for cleaning and cooling air (for printing and coding machines), ink spray heads for printing machines, parts and fittings for all the aforesaid goods. Lasers, laser beam printers, laser operated marking and identifying apparatus; parts and fittings for all the aforesaid goods.
