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
  • B41J2/135—Nozzles
  • B41J2/165—Prevention or detection of nozzle clogging, e.g. cleaning, capping or moistening for nozzles
  • B41J2/16579—Detection means therefor, e.g. for nozzle clogging
• • 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
  • B41J2/135—Nozzles
  • B41J2/165—Prevention or detection of nozzle clogging, e.g. cleaning, capping or moistening for nozzles
• • 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
  • B41J2/21—Ink jet for multi-colour printing
• • 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
  • B41J2/21—Ink jet for multi-colour printing
  • B41J2/2132—Print quality control characterised by dot disposition, e.g. for reducing white stripes or banding
  • B41J2/2139—Compensation for malfunctioning nozzles creating dot place or dot size errors
• • 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
  • B41J29/00—Details of, or accessories for, typewriters or selective printing mechanisms not otherwise provided for
  • B41J29/38—Drives, motors, controls or automatic cut-off devices for the entire printing mechanism

Definitions

• Non-contact material deposition printing is an appealing method for patterning and depositing materials in the printed electronics and solar cell industries. For example, forming conductive lines by directly depositing conductive materials on the back or front surface of the solar cell to provide a conduction path for the charge generated by the cell may increase the efficiency of the solar cell as well as the productivity of mass-manufacturing.
• Deposition printing techniques such as ink jet printing or aerosol printing involves depositing droplets of print material from nozzles by moving a print head and a substrate relative to one another along a printing direction.
• One of the problems associated with deposition printing is faulty nozzles that may stop jetting or may jet poorly. Accordingly, a faulty nozzle may result in uneven conductive lines which may lead to inefficient or inoperative solar cells.
• FIG. 1 shows an exemplary printing system according to embodiments of the invention
• FIG. 2 shows printing units having redundant nozzles and positioned parallel to the print direction helpful in demonstrating embodiments of the invention.
• FIG. 3 is a flowchart diagram illustrating a method for printing according to some embodiments of the present invention.
• Embodiments of the invention may be applicable to a variety of printing systems and methods.
• exemplary embodiments and references of non-contact material deposition systems will mostly be for the application of fabrication of conducting metal lines for solar cells using an inkjet system.
• the scope of the invention is not limited by such exemplary embodiments and may be applied to other deposition systems, such an aerosol jet deposition system or a dispenser and to other applications, such as graphics, press, mass media, packaging, electronics and others.
• Embodiments of the invention are directed to a system and method for inspection of print nozzles while a print process or a print job is in progress and replacing actively printing nozzles as needed.
• the system may comprise redundant print heads or printing units such that the number of print heads may be higher than the number of print head required to perform a desired printing task. At any given time during printing a portion of the heads may be active while the remaining print head may be redundant heads.
• a first subset selected from a plurality of print heads installed in a system would be designated to deposit material on a substrate
• a second, different subset of print heads may be subjected to, or undergo a maintenance procedure.
• a first print head is actively depositing material on a substrate
• a second print head may be relocated from a printing area or zone to an inspection, service or maintenance area. While the second print head is being inspected, serviced, repaired or otherwise subjected to a maintenance procedure, the first print head may continue to print and/or deposit material.
• the method may include printing lines on a substrate, for example printing contact lines on a semiconductor wafer by depositing material from a printing unit having nozzles arranged in one or more rows.
• the printing unit may comprise redundant nozzles.
• the number of nozzles in a printing unit may be larger than the number of nozzles needed to accomplish a desired printing task, for example printing a line at a desired resolution.
• a portion of the nozzles within a printing unit may be active while the remaining nozzles may be redundant or inactive.
• the printing is done only by nozzles designated as active nozzles while the remaining nozzles are designated as inactive nozzles.
• material may be selectively deposited
• the method may further include moving the printing unit to an inspection zone while continuing the printing with active nozzles of another printing unit, which may perform the tasks of the former printing unit.
• the inspection may be done at the printing zone without moving the printing unit to the inspection zone.
• the identified faulty nozzle may be designated as inactive and one of the previously designated as inactive nozzles may become an active nozzle to replace the faulty nozzle.
• the method may further include moving the printing unit back from the inspection zone to the printing zone and continue printing with that unit such that the new active nozzle would replace the faulty nozzle.
• the system may analyze the inspection data and may choose a best set of nozzles to be the active nozzles based on predetermined considerations. Then, the chosen nozzles may be designated or specified as active nozzles while the remaining nozzles of the printing unit would be designated as inactive. Determining the best set of nozzles may be based on a required droplet size, stability of jetting and/or choosing nozzles having substantially similar deviation of their jetting direction from a normal to the nozzle plate (orifice plate). Other parameters may be taken into consideration for choosing the best set of nozzles without departing from the scope of the invention. [0016] Reference is made to Fig.
• system 100 may be capable of executing continuous high speed, high volume print jobs without frequently stopping for maintenance or inspection. It will be noted that system 100 may be applicable to a variety of printing systems, e.g., inkjet or aerosol dispensing systems.
• System 100 may include printing units or print heads 105A- 105F 5 a printing zone 110, such as a conveyor or platform (not shown) defining the width of a print area, on which print media, such as semiconductor wafers may be placed and a service zone 125, in which maintenance and inspection of the printing units and their nozzles may take place.
• Service zone 125 may include one or more maintenance stations to perform various maintenance operations to the printing units. Although only six exemplary printing units are shown, any applicable number of printing units may be used without departing from the scope of the invention. The number of printing units is determined such that at least one printing unit is redundant. The redundancy enables the simultaneous inspection of non-active nozzles when active nozzles continue with the printing process. Accordingly, at least one printing unit from units 105 A - 105F may be capable of independently moving between printing zone 110 and service zone 125 while the other printing units remain at the printing zone and continue with the printing process. Service zone 125 may be near or in close proximity to printing zone 110. According to some embodiments of the invention, printing units 105 A-F may be mounted on rails such that they may be moved from printing zone 110 to service zone 125. Any other transport units or mechanisms may be used without departing from the scope of the invention.
• Each printing unit 105 A-F may comprise nozzles 106 arranged in one or more rows.
• each row has eight nozzles arranged in parallel to the printing or scanning direction X.
• each tow may include tens or hundreds of nozzles.
• Each row may include redundant nozzles for substitution of faulty nozzles upon detection.
• a faulty nozzle may be, for example, a clogged nozzle that cannot jet any material, a weak or partially clogged nozzle that can jet only a portion from the desired amount of material or a nozzle that jet in a direction that strongly deviates from the direction of jetting of the majority of the nozzles.
• Printing units 105 A-C may be positioned in proximity to printing zone 110 such that the rows would be parallel to the print direction X. If the substrate in moved by a conveyor, the printing direction may be represented by the direction of advance of the substrate. In such a configuration, each row may print a single metallization line in a direction parallel to the print direction in one scan. Other setups or configurations of the printing unit with respect to the print direction are possible according to other embodiments of the invention.
• System 100 may further include a controller 115 to control the printing process and an image acquisition unit 120 coupled to controller 115.
• controller 115 may perform, or be involved in, tasks or functions such as, but not limited to, coordination, configuration, scheduling, arbitration, supervising, operation and/or management of components of system 100 and their operations.
• controller 115 may control the movement of printing units 105 A-F and the printed objects in printing zone 110.
• Controller 115 may comprise any required or suitable hardware, software, firmware or a combination thereof.
• controller 115 may be a computing device comprising a controller and/or central processing unit (CPU), a memory and input and output units.
• CPU central processing unit
• Image acquisition unit 120 may comprise a detector or imaging device 121, such as camera or charge coupled device (CCD) to inspect the status and condition of the nozzles by acquiring, for example, images of droplets of material that exits the nozzles. Any other suitable visual detector or any other method of identifying the status of the nozzles may be used. Image acquisition unit 120 may further comprise an image processing unit 122 to analyze the images and determine the current status of the inspected nozzles and storage 123 to store data related to the status of the nozzles.
• CCD charge coupled device
• detector 121 may be coupled to a dedicated computing and storage device for processing and storing the captured images or alternatively controller 115 may perform these operations.
• a pulsed light source such as a pulsed laser source or a pulsed light emitting diode (LED) may be coupled to detector 121 to enable imaging of droplets being deposited from the nozzles.
• Controller 115 may further control and manage the inspection procedure, for example coordinating the ejection of droplets, the light pulses and the operation of the camera.
• Fig. 2 illustrates an array of printing units having redundant nozzles and positioned parallel to the print direction to demonstrate embodiments of the invention.
• Printing units 210, 220 and 230 may be used to print conductive lines on a semiconductor wafer in the production of solar cells.
• a first subset of nozzles may be designated as active nozzles, for example, nozzles 224-228 may be designated as active.
• a second subset of nozzles within printing unit 220, for example, nozzles 221-223 may be designated as inactive.
• the defective nozzle may be substituted by any one of the inactive nozzles 221-223.
• nozzle 225 may be re- designated as inactive and nozzle 222 may be re-designated as active.
• a print process while a print process is in progress and while one or more printing units defining a first subset of printing units is actively depositing, another one or more printing units defining a second subset of printing units may move to service zone 125 for maintenance and/or inspection. Further, if desired, the status of at least one pair of nozzles may be interchanged such that the previously active nozzle would become inactive and the previously inactive nozzle would become active.
• the printing units relocated to service zone 125 may be inspected, serviced and configured.
• nozzles may be inspected by acquiring images of droplets dispensed or ejected by nozzles of the inspected unit.
• the images may then be analyzed by image processing unit 122. Based on the analysis, faulty nozzles may be identified and replaced by redundant nozzles.
• various working parameters may be modified or verified. For example, based on the inspection of a nozzle, working parameters such as pressure, temperature or voltage may be modified.
• image processing unit 122 may receive images from detector 121 and process such images by applying any suitable image processing techniques. For example, analysis of shape, trajectory and velocity of jetted droplets may be performed by the image processing unit. For example, image processing may be used to determine a condition of a nozzle based on an image of droplets being ejected from the nozzle. Another example may be comparing two or more images, possibly acquired over a predefined period of time. By comparing or otherwise relating images, various conditions, faults or other aspects of a nozzle may be determined. For example, degradation in the performance of a nozzle may be detected by comparing consecutive or successive images. [0027] While a video camera may provide images related to visible light, other images may be produced.
• detector 121 may be an infrared camera that may record temperatures, thus providing a temperature distribution of ejected ink or aerosol. While as described herein, imaging device or detector 121 may be placed at the service area, other configurations are possible. For example, one or more cameras may be placed near, around or in proximity of a printing area, e.g., area 110. Such cameras may obtain images during the printing process of nozzles depositing material onto a test substrate.
• Storage system or unit 123 may receive and store images acquired by detector 121 and/or obtained from a different source, e.g., a remote server or a removable storage media such as a compact disk (CD) or memory chip.
• a different source e.g., a remote server or a removable storage media such as a compact disk (CD) or memory chip.
• reference images of a desired ejection may be loaded into or otherwise stored in a storage device and may be used for comparing with or otherwise relating to images acquired by detector 121.
• a reference image may contain an image of an ideal, otherwise desirable ejection or deposition and thus may be used, for example by comparing it to a second image in order to determine if an injection imaged in the second image is acceptable or otherwise determine a quality of the ejection or other functional parameters related to the nozzle from which the imaged droplet has jetted.
• the redundancy of the printing unit or print heads may enable dynamically selecting the print heads that participate in a print process. Accordingly, redundant, spare, unused or idle print heads may exist and/or be available during a print process. Such redundant print heads may enable dynamic replacement of print heads while a print process is ongoing, active or in progress. For example, if a first print head is active, e.g., actively participating in a print process by depositing material on a media, needs, or is selected to be serviced or inspected, a second, inactive, idle or redundant print head may replace the first print head by being made active. Accordingly, the first print head, now being replaced, may be made inactive and may further be inspected, serviced or be otherwise subjected to a maintenance procedure.
• a first print head is active, e.g., actively participating in a print process by depositing material on a media, needs, or is selected to be serviced or inspected
• a second, inactive, idle or redundant print head may replace the first print head by being made active
• the printing units or print heads may be equipped with redundant nozzles.
• a print head that may require one hundred (100) nozzles in order to perform its intended tasks may be equipped with five hundred (500) nozzles. Accordingly, only a subset of nozzles fitted, included or installed in a print head may actively participate in. a print process, e.g., actually eject material onto a surface or media.
• redundancy of nozzles as described herein may enable dynamically selecting or designating a subset of nozzles as active. Such redundancy may further enable replacing active nozzles by inactive ones. For example, upon determining that a first nozzle in a print head needs to be replaced or serviced, e.g., due to a malfunction or as part of a scheduled or periodic maintenance routine, a second, inactive or redundant nozzle may be selected, made active, and may replace the first nozzle by ejecting material onto a surface or media.
• the method may include commencing a print process using a first printing unit or print head.
• information in a print file may be provided to a printing system such as system 100 described in Fig. 1.
• controller 115 may cause a conveyor to locate wafers such that a subset of nozzles, designated as active nozzles in both printing units 230 and 220 may deposit conductive material on them.
• controller 115 may control the nozzles and printing units such that material is deposited according to specifications or parameters in the print file.
• the method may include moving the one or more printing units, for example printing unit 220 to a service zone. During the time that the printing unit is being inspected and/or serviced at the service zone, another printing unit, such as printing unit 210 that was previously redundant may become active so that the printing process may continue with printing units 210 and 230. As shown by block 330, the method may include inspecting the nozzles of printing unit 200 and identifying one or more nozzles, for example nozzle 225 as faulty or defective nozzle.
• the method may include determining whether the fault can be repaired. For example, if a total obstruction of a nozzle's orifice is detected, a procedure may exist to remove the obstructions from the orifice thus repairing the fault. Other detected faults may be such that require a complex, possibly manual procedure in order to be fixed. Classifying a fault as one that may be handled or repaired immediately or while a print process is in progress may be according to various parameters and/or configurations. If the fault may be repaired, flow may include servicing the nozzle. For example, the working parameters may be modified or an automated purging procedure may be executed. [0034] As shown by block 335, the method may include choosing a best set of nozzles as best nozzles based on the inspection.
• the method may include designating a faulty nozzle as inactive when repair is impossible or undesirable. Nozzles identified as inactive may not participate in the printing process until their status is changed to "active". As shown by block 340, the method may comprise designating the nozzles of the chosen set as active and the faulty nozzles and remaining nozzles of the printing unit as inactive. For example, the method may include designating a nozzle, from the same row of the newly faulty nozzle that was previously designated an inactive nozzle as active. For example, after determining that nozzle 225 is faulty, a redundant nozzle that was previously inactive and did not participate in the printing process, such as nozzle 223 may be designated as an active nozzle that would replace the faulty nozzle 225.
• a first, faulty nozzle may be designated as inactive and a second, inactive nozzle may be designated as active in order to compensate for the faulty nozzle
• nozzles with the same printing unit and possibly the same row may be replaced based on a predefined schedule.
• nozzles may be designated as active or inactive periodically.
• a first nozzle may be replaced by a second nozzle
• other combinations are possible.
• a faulty nozzle may be replaced by two redundant nozzles. For example, such two nozzles may be instructed such that their combined operation is the same as an expected operation of the faulty, replaced nozzle.
• the method may include after the inspection is over, moving the first printing unit back to the printing zone.
• printing unit 220 may replace, for example, printing unit 210 in performing the ongoing print process and printing unit 210 may be moved to the service area for inspection.
• printing unit 220 may replace, for example, printing unit 230 in performing the ongoing print process and printing unit 230 may be moved to the service area for inspection.
• the method may comprise ceasing to print with a working printing unit and continuing with the print process using the first printing unit.
• the first printing unit may be for example, unit 220 in which the newly active nozzle, nozzle 221 replaces the previously used and now faulty nozzle 225.
• Embodiments of the invention may include an article such as a computer or processor readable medium, or a computer or processor storage medium, such as for example a memory, a disk drive, or a USB flash memory, encoding, including or storing instructions, e.g., computer-executable instructions, which when executed by a processor or controller, carry out methods disclosed herein.
• a computer or processor readable medium such as for example a memory, a disk drive, or a USB flash memory
• encoding including or storing instructions, e.g., computer-executable instructions, which when executed by a processor or controller, carry out methods disclosed herein.
• the terms “plurality” and “a plurality” as used herein may include, for example, “multiple” or “two or more”.
• the terms “plurality” or “a plurality” may be used throughout the specification to describe two or more components, devices, elements, units, parameters, or the like.

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• Engineering & Computer Science (AREA)
• Quality & Reliability (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Ink Jet (AREA)
• Coating Apparatus (AREA)
• Manufacturing Of Printed Wiring (AREA)

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• 2009
  • 2009-06-18 EP EP09766330A patent/EP2313277B1/en active Active
  • 2009-06-18 AT AT09766330T patent/ATE556851T1/de active
  • 2009-06-18 WO PCT/IL2009/000612 patent/WO2009153795A1/en active Application Filing
  • 2009-06-18 CN CN200980123292.5A patent/CN102574396B/zh active Active
  • 2009-06-18 JP JP2011514200A patent/JP2011526199A/ja active Pending
  • 2009-06-18 KR KR1020117001294A patent/KR101641392B1/ko active IP Right Grant
  • 2009-06-19 TW TW098120609A patent/TWI448390B/zh active
• 2014
  • 2014-07-10 JP JP2014142159A patent/JP5972937B2/ja not_active Expired - Fee Related

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