Patent Application
20100253739
This invention relates in general terms to an inkjet printer and, in particular to pagewidth printhead assemblies with associated capping mechanisms and or nozzle purging systems. By “pagewidth” printhead assembly it is meant an assembly having a printhead with a length which extends across substantially the full width of the media (paper, card, textile or other) to be printed and which, whilst remaining in a stationary position, is controlled to deposit printing ink across the full print width of advancing print media.
The following applications have been filed by the Applicant with the present application:
The disclosures of these co-pending applications are incorporated herein by reference.
The following patents or patent applications filed by the applicant or assignee of the present invention are hereby incorporated by cross-reference.
Inkjet printers have a series of nozzles from which individual ink droplets are ejected to deposit on print media to form desired printed images. The nozzles are incorporated in various types of printheads and their proper functioning is critical to the creation of quality images. Thus, any partial or total blockage of even a single nozzle may have a significant impact on a printed image, particularly in the case of a pagewidth printer.
The nozzles are prone to blockage due to their exposure to ever-present paper dust and other particulate matter and due to the tendency of ink to dry in the nozzles during, often very short, idle periods. Prior to ejection, the ink forms a meniscus at the nozzle opening. Exposure to air (frequently warm) evaporates the ink solvent to leave a solid deposit that can block the nozzle.
Servicing systems are conventionally employed for maintaining the functionality of printheads. Such systems provide capping, purging and or wiping. Capping involves the covering of idle nozzles to preclude exposure of ink to drying air. Purging is normally effected by evacuating a capping chamber, thereby sucking deposits from the printhead that block or have the potential to block the nozzles. Wiping is performed in conjunction with the capping and/or purging functions and involves gently sweeping a membrane across the face of the printhead.
Most conventional inkjet printers use a reciprocating printhead which is traverses across the width of a momentarily stationary page or portion of print media. In these printers, service stations are provided at one side of the printing zone and, on command, the printhead is traversed to the service station where it is docked while servicing is performed and or the printer is idle.
The above described servicing system is not feasible for pagewidth printers because of the stationary printhead assembly that extends across the full width of the printing zone. The printhead assembly effectively defines the print zone and it cannot be moved outside of that zone for servicing. Furthermore, a pagewidth printhead has a significantly larger surface area and contains a vastly greater number of nozzles than a conventional inkjet printhead, especially in the case of a large format printer. These factors dictate that the servicing of printheads requires an entirely different approach to that of conventional scanning type printheads.
In the drawings—
As illustrated in
Each of the printheads 51 may, for example, be in the form of that which is described in the Applicant's co-pending US patent applications listed in the cross-references section above and all of which are incorporated herein by reference. But other types of pagewidth printheads (including thermal or piezo-electric activated bubble jet printers) that are known in the art may alternatively be employed.
As illustrated in
However, it will be understood that each of the printheads 51 may comprise substantially more than four modules 55 and/or that substantially more than four printhead chips 57 may be mounted to each module.
Each of the chips (as described in more detail later) has up to 7680 nozzles formed therein for delivering printing fluid onto the surface of the print media and, possibly, a further 640 nozzles for delivering pressurised air or other gas toward the print media.
The four printhead modules 55 are removably located in a channel portion 60 of a casing 61 by way of the support member 56, and the casing contains electrical circuitry 63 mounted on four printed circuit boards 62 (one for each printhead module 55) for controlling delivery of computer regulated power and drive signals by way of flexible PCB connectors 63a to the printhead chips 57. As illustrated in
The printed circuit boards 62 are carried by plastics material mouldings 66 which are located within the casing 61 and the mouldings also carry busbars 67 which in turn carry current for powering the printhead chips 57 and the electrical circuitry. A cover 68 normally closes the casing 61 and, when closed, the cover acts against a loading element 69 that functions to urge the flexible printed circuit connector 59 against the busbars 67.
The four printhead modules 55 may incorporate four conjoined support members 56 or, alternatively, a single support member 56 may be provided to extend along the full length of the printhead 51 and be shared by all four printhead modules. That is, a single support member 56 may carry all sixteen printhead chips 57.
As shown in
A coupling device 73 is provided for coupling fluid into the seven channels 70 from respective ones of the fluid delivery lines 65.
The fluid distribution arrangements 58 are provided for channeling fluid (printing ink and air) from each group 71 of holes to an associated one of the printhead chips 57. Printing fluids from six of the seven channel 70 are delivered to twelve rows of nozzles on each printhead chip 57 (i.e., one fluid to two rows) and the millimetric-to-micrometric distribution of the fluids is effected by way of the fluid distribution arrangements 58. For a more detailed description of one arrangement for achieving this process reference may be made to the co-pending US patent applications referred to previously.
An illustrative embodiment of one printhead chip 57 is described in more detail, with reference to
A print media guide 74 is mounted to each of the printheads 51 and is shaped and arranged to guide the print media past the printing zone, as defined collectively by the printhead chips 57, in a manner to preclude the print media from contacting the nozzles of the printhead chips.
The fluids to be delivered to the printheads 51 will be determined by the functionality of the printer 52. However, as illustrated, provision is made for delivering six printing fluids and air to the printhead chips 57 by way of the seven channels 70 in the support member 56. The six printing fluids may comprise:
The filtered air will in use be delivered at a pressure slightly above atmospheric from a pressurised source (not shown) that is integrated in the printer.
Having identified the salient features of the pagewidth printheads, different aspects and embodiments will now be illustrated diagrammatically with reference to the capping arrangements shown in
In the mechanism shown in
Two capping members 82 are located adjacent the printheads and are inclined at an angle of approximately 40 degrees to the direction of print media feed.
When capping is required, for example between successive print runs, the printheads 51 are turned in an arcuate direction through 40 degrees to the position shown in
Actuating mechanisms 84 and 85, as shown in block diagrammatic form in
With the mechanism as illustrated in
Each of the capping members 82 has a configuration as shown in
The lip portion 101 is peripherally configured to surround the printhead chips 57 collectively and the adjacent region of the printing zone of each or the printheads 51. Also, the cavity 102 may be provided or be lined with a hydrophobic material or a hydrophilic material, depending upon the function of the capping member and whether fluid that is purged from the printhead is to be expelled from or retained in the capping member
Each of the capping members 82 may be formed as a one-piece member with a length that corresponds with that of a printhead to be capped or it may be formed from conjoined shorter-length portions that have an aggregate length corresponding to that of the printhead.
In the mechanism shown in
Two capping members 82 are located adjacent the printheads and are inclined at an angle of approximately 40 degrees to the direction of print media feed.
When capping is required, for example between successive print runs, the printheads 51 are turned in an arcuate direction through 40 degrees to the position shown in
Actuating mechanisms 84 and 85, as shown in block diagrammatic form in
With the mechanism as illustrated in
Each of the capping members 82 has a configuration as shown in
In the mechanism shown in
When capping is required, any print media that is positioned in the printer is moved in the direction of arrow 88 by rollers 89 and the upper printhead 51 is raised (relative to the lower printhead) by an actuating mechanism 87, as indicated in
The actuating mechanisms 87 and 90, as shown in block diagrammatic form in
The capping member 82 is double sided, having in effect two capping portions 86, and has a configuration as shown in
The lip portion 101 is peripherally configured to surround the printhead chips 57 collectively and the adjacent region of the printing zone of each or the printheads 51. Also, the cavity 102 may be provided or be lined with a hydrophobic material or a hydrophilic material, depending upon the function of the capping member and whether fluid that is purged from the printhead is to be expelled from or retained in the capping member.
The capping member 82 may be formed, effectively, as a one-piece member with a length that corresponds with that of the printhead to be capped or it may be formed from conjoined shorter-length portions that have an aggregate length corresponding to that of the printhead.
As illustrated, a capping member 82 is initially located below the plane of print media feed 81 through the printer and, following the extraction of any print media in the direction indicated by arrow 84, the capping member is moved rectilinearly upward by an actuating mechanism 83 to the position shown in
The actuating mechanism 83 may comprise a geared motor drive, pneumatic actuator or other such mechanism as is known in the art for effecting movement of relatively small mechanical devices.
The capping member 82 is moved in a direction normal to the printhead 51, thereby avoiding any potential for rubbing between the capping member and the printing zone of the printhead.
The capping member 82 has a configuration as shown in
As illustrated, a capping member 82 is initially located below the plane of print media feed 81 through the printer and, following the extraction of any print media in the direction indicated by arrow 80, the capping member is moved rectilinearly upward by an actuating mechanism 83 to the position shown in
The actuating mechanism 83 may comprise a geared motor drive, pneumatic actuator or other such mechanism as is known in the art for effecting movement of relatively small mechanical devices.
The capping member 82 doubles as a purging member and it incorporates a chamber 84 that communicates by way of a port 85 with a cavity 86. An extractor tube 87 extends into the chamber 84 and is connected to a suction pump or other such device 88 within the printer for sucking purged material from the nozzle environment of the printhead 51.
The capping member 82 is moved by the actuating mechanism 83 in a direction normal to the printhead 51, thereby avoiding potential for rubbing between the capping member and the printing zone of the printhead.
The capping member 82 has a configuration as shown in
As illustrated, capping members 82 are initially located in vertical spaced relationship to the respective printheads 51 and, thus, are located one at each side of the plane 81 of print media feed through the printer. Following the extraction of any print media from between the printheads 51, the capping members are moved rectilinearly in mutually opposite vertical directions by actuating mechanisms 80, to the positions shown in
Each of the actuating mechanisms 80 may comprise a geared motor drive, pneumatic actuator or other such mechanism as is known in the art for effecting movement of relatively small mechanical devices.
The capping members 82 are moved in a direction normal to the printheads 51, thereby avoiding any potential for rubbing between the capping members and the printing zone of the printheads.
Each of the capping members 82 has a configuration as shown in
As illustrated, a capping member 82 is initially located below the plane of print media feed 81 through the printer and, following the extraction of any print media in the direction indicated by arrow 80, the capping member is moved arcuately upwardly by an actuating mechanism 83 to the position shown in
The actuating mechanism 83 may comprise a geared motor drive, pneumatic actuator or other such mechanism as is known in the art for effecting movement of relatively small mechanical devices.
The capping member 82 is moved in a direction approximately normal to the printhead 51, thereby avoiding any potential for significant rubbing between the capping member and the printing zone of the printhead.
The capping member 82 has a configuration as shown in
As illustrated, a capping member 82 is initially located below the plane 81 of print media feed through the printer and, following the extraction of any print media in the direction indicated by arrow 80, the capping member is moved arcuately in an upward by an actuating mechanism 83 to the position shown in
The actuating mechanism 83 may comprise a geared motor drive, pneumatic actuator or other such mechanism as is known in the art for effecting movement of relatively small mechanical devices.
The capping member 82 doubles as a purging member and it incorporates a chamber 84 that communicates by way of a port 85 with a cavity 86. An extractor tube 87 extends into the chamber 84 and is connected to a suction pump or other such device 88 within the printer for sucking purged material from the nozzle environment of the printhead 51.
The capping member 82 is moved by the actuating mechanism 83 in a direction that is approximately normal to the printhead 51, thereby avoiding potential for significant rubbing between the capping member and the printing zone of the printhead.
Each of the capping members 82 has a configuration as shown in
In the mechanism shown in
Two capping members 82 are located adjacent the printheads and are inclined at an angle of approximately 40 degrees to the direction of print media feed.
When capping is required, for example between successive print runs, the printheads 51 are turned in an arcuate first direction through 40 degrees to the position shown in
Actuating mechanisms 83 and 84, as shown in block diagrammatic form in
With the mechanism as illustrated in
Each of the capping members 82 has a configuration as shown in
In the mechanism shown in
When capping is required, for example between successive print runs, the printheads 51 are turned in an arcuate first direction from a non-capping first position to a second position as shown in
Thereafter, the capping/purging members 82 are turned in an arcuate second direction, opposite to that of the first direction, through to the second position shown in
Actuating mechanisms 83 and 84, as shown in block diagrammatic form in
The capping/purging member 82 incorporates a purging chamber 86 (see
If purging is required following capping of the printhead chips 57 on the printheads 51, the printheads 51 are turned in the first direction through a further angle, as shown in
If purging is required independently of capping, the printheads 51 will be turned though the full extent from the first to the third position by the actuating mechanisms 83, and the capping/purging members 82 will be turned in the opposite direction by the actuating mechanisms 84, so that the printhead chips 57 will align with the purging chambers 86.
The capping and/or purging operations may be performed in the above described apparatus without interfering with the movement of print media. Thus, the print media may be maintained in position between the printheads 51 during the capping and purging operation.
Each of the capping/purging members 82 has a configuration as shown in
The lip portion 101 is peripherally configured to surround the printhead chips 57 collectively and the adjacent region of the printing zone of each or the printheads 51 during both the capping and the purging operations.
Each of the capping/purging members 82 may be formed as a one-piece member with a length that corresponds with that of a printhead to be capped or it may be formed from conjoined shorter-length portions that have an aggregate length corresponding to that of the printhead.
The mechanism that is illustrated in
When positioned adjacent (i.e., just below) the printing head 51, the platen 91 provides support for normal print media feed through the printer. When capping and/or purging is required, the turret 90 is initially lowered by a first actuating mechanism 94 and is rotated by a second actuating mechanism 95 to position the capping member 92 or the purging chamber 93 in alignment with the printhead 51. Thereafter, the turret is again raised by the actuating mechanism 94 to the position shown in
When the purging chamber 96 is located in contact with the printhead chips 57, purging may be effected and the purged material be sucked out by way of an extractor tube 96 that is connected to a suction device 97, such as a pump, in the printer.
The actuating mechanisms 94 and 95, as shown in block diagrammatic form, may comprise geared motor drives, pneumatic actuators or such other mechanisms as are known in the art for effecting movement of relatively small mechanical devices.
The capping member 92 and the purging chamber 93 as mounted to the turret 90 may each have the configuration as illustrated in
The lip portion 101 is peripherally configured to surround the printhead chips 57 collectively and the adjacent region of the printing zone of each or the printheads 51. In the case of the purging chamber 93, an aperture 103 is provided (or a plurality of such apertures are provided) in the cavity 102 to connect with the extractor tube 96 by way of a port 104 and a central bore 105 of the turret 90.
The capping member/purging chamber 92/93 may be formed as a one-piece member with a length that corresponds with that of the printhead 51 to be capped or it may be formed from conjoined shorter-length portions that have an aggregate length corresponding to that of the printhead.
As an alternative to the use of the purging chamber 93, the nozzles 57 may be purged directly into an aperture or a ported recess (herein referred to as a purging chamber) in the turret when the turret is rotated to the appropriate position.
The mechanism that is illustrated in
The eccentric land portion 93 of the turret carries a longitudinally extending capping member 94 that extends for substantially the full length of the printhead 51. Also, a purging chamber 95 is located within the turret 90 and opens to the flat land portion 92 by way of a port 96.
The flat land portion 92 of the turret effectively forms a platen and, when the turret is in the position shown in
When capping is required, for example between successive print runs, the turret 90 is rotated to the position shown in
An actuating mechanism 97 is provided for effecting required rotation of the turret 90. That mechanism may comprise a geared motor drive, a pneumatic actuator or such other mechanism as is known in the art for effecting movement of relatively small mechanical devices.
When purging of the nozzles is to be effected, the turret is rotated to the position shown in
The capping member 94 as mounted to the turret 90 may have the configuration as illustrated in
The lip portion 101 is peripherally configured to surround the printhead chips 57 collectively and the adjacent region of the printing zone of each or the printheads 51. Also, the cavity 102 may be provided or be lined with a hydrophobic material or a hydrophilic material, depending upon the function of the capping member and whether fluid that is purged from the printhead is to be expelled from or retained in the capping member.
The capping member 94 may be formed as a one-piece member with a length that corresponds with that of the printhead 51 to be capped or it may be formed from conjoined shorter-length portions that have an aggregate length corresponding to that of the printhead.
The mechanism that is illustrated in
A longitudinally extending capping member 93 is pivotally mounted to the carrier 90 and it too has a longitudinal length corresponding substantially to that of the printhead 51.
An actuating mechanism 94 is provided and arranged to effect pivoting of the capping member 93 from a non-capping first position as indicated in
The actuating mechanism 94 may comprise a geared motor drive, a pneumatic actuator or such other mechanism as is known in the art for effecting movement of relatively small mechanical devices.
When capping is required, for example between successive print runs, the capping member 93 may simply be pivoted from the first to the second position, as described above, without effecting any movement of the carrier 90. In this case the carrier would be located a small distance below the printhead 51 and, in effect, define the lower margin of a passage through which print media is transported during a normal printing operation. In an alternative arrangement (not shown), the carrier 90 might be positioned well below the printhead 51 when the capping member 93 is in the first position and a further actuating mechanism would then be provided for elevating the carrier to the required capping position.
When purging of the nozzles is to be effected, the capping member 93 is pivoted to the position shown in
The capping member 93 as pivotally mounted to the carrier 90 may have the configuration illustrated in
The lip portion 101 is peripherally configured to surround the printhead chips 57 collectively and the adjacent region of the printing zone of each or the printheads 51. Also, the cavity 102 may be provided or be lined with a hydrophobic material or a hydrophilic material, depending upon the function of the capping member and whether fluid that is purged from the printhead is to be expelled from or retained in the capping member.
As illustrated in
The capping member 83 is directed into the gap 80 by way of a ramp or chute 84 and an actuating mechanism 85 is employed for propelling the capping member into the desired position. The actuating mechanism may comprise a geared motor drive, pneumatic actuator or other such mechanism as is known in the art for effecting movement of relatively small mechanical devices.
The capping member is dimensioned to cover the confronting surfaces of the printheads 51 and, thus, it has a depth (in the direction of arrow 82) approximately equal to that of the printhead 51 and a width (in the direction into the page) which is approximately equal to the length of the printheads.
The capping member 83 may be formed from various types of materials that have a sheet-like form and are flexible. The sheet-like form is required in order that the capping member might be inserted into the relatively narrow gap 80 that will normally be present between the printheads 51, and flexibility is required to enable the creation of an effective capping seal between the capping member and the printheads.
The material from which the capping member 83 is formed will be dependent upon whether simple capping is required or whether the capping member is required also to absorb and carry purged ink and other material away from the printing zone of the printheads. For simple capping the material might be selected for hydrophobic properties, and when required to assist in purging functions the material might be selected for hydrophilic properties. The former material might comprise a closed cell thermoplastics material and the latter material might comprise and open cell silicone material.
In any event, the material from which the capping member is formed will normally exhibit a degree of compressibility in order that a positive reactive force might be established and maintained between the printheads and the capping member during the capping operation. Alternatively or additionally, the capping member 83 might be formed from layered sheets, so that a fluid (i.e., a liquid or a gas) might be directed into the region between the layers to change the effective thickness of the capping member. A fluid delivery mechanism 86 is shown in
The mechanism that is illustrated in
A capping member 83 is provided in the form of a replaceable roll 84 of sheet material of a type to be described (by way of example) and, when a capping operation is to be performed, for example between print runs, the following operations are performed:
When capping is no longer required and a purging operation, if any, has been completed, the spent capping member 83 is separated from the roll 84 by a cutter mechanism 86 and the capping member is drawn from the gap 81 in the direction opposite to that indicated by arrow 82.
Feeding of the capping member 83 into and out from the gap 81 may be effected manually or mechanically, depending upon the size and required operating speed of the printer of which the capping mechanism forms a part.
When the capping mechanism as illustrated is employed in a wide format printer, the cutter mechanism 86 may comprise one that typically is used to effect the cutting of print media that is fed through the printer from a roll of the print media.
The actuating mechanism 85 may comprise a geared motor drive, pneumatic actuator or other such mechanism as is known in the art for effecting movement of relatively small mechanical devices.
The capping member is dimensioned to cover the confronting surfaces of the printheads 51 and, thus, it has a width (in the direction into the page) which is approximately equal to the length of the printheads.
The capping member 83 may be formed from various types of materials that have a sheet-like form and are flexible. The sheet-like form is required in order that the capping member might be inserted into the relatively narrow gap 81 that will normally be present between the printhead 51 and the platen 80 (or between two printheads in the case of a duplex assembly), and flexibility is required to enable the creation of an effective capping seal between the capping member and the printhead(s).
The material from which the capping member 83 is formed will be dependent upon whether simple capping is required or whether the capping member is required also to absorb and carry purged ink and other material away from the printing zone of the printhead. For simple capping the material might be selected for hydrophobic properties, and when required to assist in purging functions the material might be selected for hydrophilic properties. The former material might comprise a closed cell thermoplastics material and the latter material might comprise and open cell silicone material.
In any event, the material from which the capping member is formed will normally exhibit a degree of compressibility in order that a positive reactive force might be established and maintained between the printheads and the capping member during the capping operation. Alternatively or additionally, the capping member 83 might be formed from layered sheets, so that a fluid (i.e., a liquid or a gas) might be directed into the region between the layers to change the effective thickness of the capping member.
The mechanism that is illustrated in
A capping member 83 is provided in the form of a portion of a replaceable roll 84 of sheet material of a type to be described (by way of example), and a take-up reel 85 is provided for storing spent sheet material 83 following a capping and/or purging operation.
When a capping operation is to be performed, for example between print runs, the following operations are performed:
When capping is no longer required and a purging operation, if any, has been completed, the spent capping member portion of the capping material 83 is moved through the gap 81 and wound onto the take-up reel 85.
Feeding of the capping member 83 into and out from the gap 81 may be effected manually or mechanically, depending upon the size and required operating speed of the printer of which the capping mechanism forms a part.
The actuating mechanism 85 may comprise a geared motor drive, pneumatic actuator or other such mechanism as is known in the art for effecting movement of relatively small mechanical devices.
The roll 84 of sheet-like capping material has a width (in the direction into the page) which is approximately equal to the length of the printheads.
The capping member 83 may be formed from various types of materials that have a sheet-like form and are flexible. The sheet-like form is required in order that the capping member might be inserted into the relatively narrow gap 81 that will normally be present between the printhead 51 and the platen 80 (or between two printheads in the case of a duplex assembly), and flexibility is required to enable the creation of an effective capping seal between the capping member and the printhead(s).
The material from which the capping member 83 is formed will be dependent upon whether simple capping is required or whether the capping member is required also to absorb and carry purged ink and other material away from the printing zone of the printhead.
For simple capping the material might be selected for hydrophobic properties, and when required to assist in purging functions the material might be selected for hydrophilic properties. The former material might comprise a closed cell thermoplastics material and the latter material might comprise and open cell silicone material.
In any event, the material from which the capping member is formed will normally exhibit a degree of compressibility in order that a positive reactive force might be established and maintained between the printheads and the capping member during the capping operation. Alternatively or additionally, the capping member 83 might be formed from layered sheets, so that a fluid (i.e., a liquid or a gas) might be directed into the region between the layers to change the effective thickness of the capping member.
In the mechanism shown in
When capping is required, any print media that is positioned in the printer is moved in the direction of arrow 84 by rollers 85 and the upper printhead 51 is raised (relative to the lower printhead) by an actuating mechanism 86, as indicated in
The actuating mechanisms 86 and 87, as shown in block diagrammatic form in
The capping member 82 may, as illustrated in
As illustrated, the capping member 82 has a body portion 90 onto which is moulded or otherwise secured a capping portion having an integrally formed lip portion 91 which surrounds a cavity 92. The body portion 90 is formed from a metal such as aluminium or from a rigid plastics material, and the capping portion (including the lip portion 91) is formed from an elastomeric material.
The lip portion 91 is peripherally configured to surround the printhead chips 57 collectively and the adjacent region of the printing zone of each or the printheads 51. Also, the cavity 92 may be provided or be lined with a hydrophobic material or a hydrophilic material, depending upon the function of the capping member and whether fluid that is purged from the printhead is to be expelled from or retained in the capping member.
The capping member 82 may be formed as a one-piece member with a length that corresponds with that of the printhead to be capped or it may be formed from conjoined shorter-length portions that have an aggregate length corresponding to that of the printhead.
The interior or underside of the capping member as illustrated in
One of the printhead chips 57 is now described in more detail with reference to
As indicated above, each printhead chip 57 is provided with 7680 printing fluid delivery nozzles 150. The nozzles are arrayed in twelve rows 151, each having 640 nozzles, with an inter-nozzle spacing X of 32 microns. Adjacent rows are staggered by a distance equal to one-half of the inter-nozzle spacing so that a nozzle in one row is positioned mid-way between two nozzles in adjacent rows. Also, there is an inter-nozzle spacing Y of 80 microns between adjacent rows of nozzles.
Two adjacent rows of the nozzles 150 are fed from a common supply of printing fluid. This, with the staggered arrangement, allows for closer spacing of ink dots during printing than would be possible with a single row of nozzles and also allows for a level of redundancy that accommodates nozzle failure.
The printhead chips 57 are manufactured using an integrated circuit fabrication technique and, as previously indicated, embody micro-electromechanical systems (MEMS). Each printhead chip 57 includes a silicon wafer substrate 152, and a 0.42 micron 1 P4M 12 volt CMOS micro-processing circuit is formed on the wafer. Thus, a silicon dioxide layer 153 is deposited on the substrate 152 as a dielectric layer and aluminium electrode contact layers 154 are deposited on the silicon dioxide layer 153. Both the substrate 152 and the layer 153 are etched to define an ink channel 155, and an aluminium diffusion barrier 156 is positioned about the ink channel 155.
A passivation layer 157 of silicon nitride is deposited over the aluminium contact layers 154 and the layer 153. Portions of the passivation layer 157 that are positioned over the contact layers 154 have openings 158 therein to provide access to the contact layers.
Each nozzle 150 includes a nozzle chamber 159 which is defined by a nozzle wall 160, a nozzle roof 161 and a radially inner nozzle rim 162. The ink channel 155 is in fluid communication with the chamber 159.
A moveable rim 163, that includes a movable seal lip 164, is located at the lower end of the nozzle wall 160. An encircling wall 165 surrounds the nozzle and provides a stationery seal lip 166 that, when the nozzle 150 is at rest as shown in
The nozzle wall 160 forms part of lever arrangement that is mounted to a carrier 168 having a generally U-shaped profile with a base 169 attached to the layer 157. The lever arrangement also includes a lever arm 170 that extends from the nozzle wall and incorporates a lateral stiffening beam 171. The lever arm 170 is attached to a pair of passive beams 172 that are formed from titanium nitride and are positioned at each side of the nozzle as best seen in
The lever arm 170 is also attached to an actuator beam 173, which is formed from TiN. This attachment to the actuator beam is made at a point a small but critical distance higher than the attachments to the passive beam 172.
As can best be seen from
The actuator beam 173 is conductive, being composed of TiN, but has a sufficiently high electrical resistance to generate self-heating when a current is passed between the electrodes 174 and 175. No current flows through the passive beams 172, so they do not experience thermal expansion.
In operation, the nozzle is filled with ink 177 that defines a meniscus 178 under the influence of surface tension. The ink is retained in the chamber 159 by the meniscus, and will not generally leak out in the absence of some other physical influence.
To fire ink from the nozzle, a current is passed between the contacts 174 and 175, passing through the actuator beam 173. The self-heating of the beam 173 causes the beam to expand, and the actuator beam 173 is dimensioned and shaped so that the beam expands predominantly in a horizontal direction with respect to
The relative horizontal inflexibility of the passive beams 172 prevents them from allowing much horizontal movement of the lever arm 170. However, the relative displacement of the attachment points of the passive beams and actuator beam respectively to the lever arm causes a twisting movement that, in turn, causes the lever arm 170 to move generally downwardly with a pivoting or hinging motion. However, the absence of a true pivot point means that rotation is about a pivot region defined by bending of the passive beams 172.
The downward movement (and slight rotation) of the lever arm 170 is amplified by the distance of the nozzle wall 160 from the passive beams 172. The downward movement of the nozzle walls and roof causes a pressure increase within the chamber 159, causing the meniscus 178 to bulge as shown in
As shown in
Immediately after the drop 179 detaches, the meniscus 178 forms the concave shape shown in
As can best be seen from
As stated previously the integrated circuits of the printhead chips 57 are controlled by the print engine controller (PEC) integrated circuits of the drive electronics 63. One or more PEC integrated circuits 100 is or are provided (depending upon the printing speed required) in order to enable page-width printing over a variety of different sized pages or continuous sheets. As described previously, each of the printed circuit boards 62 carried by the support moulding 66 carries one PEC integrated circuit 190 (
An example of a PEC integrated circuit which is suitable for driving the printhead chips is described in the Applicant's co-pending U.S. patent application Ser. Nos. 09/575,108 (Docket No. PEC01US), 09/575,109 (Docket No. PEC02US), 09/575,110 (Docket No. PEC03US), 09/607,985 (Docket No. PEC04US), 09/607,990 (Docket No. PEC05US) and 09/606,999 (Docket No. PEC07US), which are incorporated herein by reference. However, a brief description of the circuit is provided as follows with reference to
The data flow and functions performed by the PEC integrated circuit 190 are described for a situation where the PEC integrated circuit is provided for driving a printhead 51 having a plurality of printhead modules 55; that is four modules as described above. As also described above, each printhead module 55 provides for six channels of fluid for printing, these being:
As indicated in
Due to the page-width form of the printhead assembly, each image should be printed at a constant speed to avoid creating visible artifacts. This means that the printing speed should be varied to match the input data rate. Document rasterization and document printing are therefore decoupled to ensure the printhead assembly has a constant supply of data. In this arrangement, an image is not printed until it is fully rasterized and, in order to achieve a high constant printing speed, a compressed version of each rasterized page image is stored in memory.
Because contone colour images are reproduced by stochastic dithering, but black text and line graphics are reproduced directly using dots, the compressed image format contains a separate foreground bi-level black layer and background contone colour layer. The black layer is composited over the contone layer after the contone layer is dithered. If required, a final layer of tags (in IR or black ink) is optionally added to the image for printout.
Dither matrix selection regions in the image description are rasterized to a contone-resolution bi-lev bitmap which is losslessly compressed to negligible size and which forms part of the compressed image. The IR layer of the printed page optionally contains encoded tags at a programmable density.
Each compressed image is transferred to the PEC integrated circuit 190 where it is then stored in a memory buffer 195. The compressed image is then retrieved and fed to an image expander 196 in which images are retrieved. If required, any dither may be applied to any contone layer by a dithering means 197 and any black bi-level layer may be composited over the contone layer by a compositor 198 together with any infrared tags which may be rendered by the rendering means 199. The PEC integrated circuit 190 then drives the integrated circuits of the printhead chips 57 to print the composite image data at step 200 to produce a printed image 201.
The process performed by the PEC integrated circuit 190 may be considered to consist of a number of distinct stages. The first stage has the ability to expand a JPEG-compressed contone CMYK layer. In parallel with this, bi-level IR tag data can be encoded from the compressed image. The second stage dithers the contone CMYK layer using a dither matrix selected by a dither matrix select map and, if required, composites a bi-level black layer over the resulting bi-level K layer and adds the IR layer to the image. A fixative layer is also generated at each dot position wherever there is a need in any of the C, M, Y, K, or IR channels. The last stage prints the bi-level CMYK+IR data through the printhead assembly 50.
The PEC integrated circuit 190 effectively performs four basic levels of functionality:
These functions are now described in more detail with reference to
The PEC integrated circuit 190 incorporates a simple micro-controller CPU core 204 to perform the following functions:
In order to perform the image expansion and printing process, the PEC integrated circuit 190 includes a high-speed serial interface 208 (such as a standard IEEE 1394 interface), a standard JPEG decoder 209, a standard Group 4 Fax decoder 210, a custom half-toner/compositor (HC) 211, a custom tag encoder 212, a line loader/formatter (LLF) 213, and a printhead interface 214 (PHI) which communicates with the printhead chips 57. The decoders 209 and 210 and the tag encoder 212 are buffered to the HC 211. The tag encoder 212 allocates infrared tags to images.
The print engine function works in a double-buffered manner. That is, one image is loaded into the external DRAM 207 via a DRAM interface 215 and a data bus 216 from the high-speed serial interface 208, while the previously loaded image is read from the DRAM 207 and passed through the print engine process. When the image has been printed, the image just loaded becomes the image being printed, and a new image is loaded via the high-speed serial interface 208.
At the aforementioned first stage, the process expands any JPEG-compressed contone (CMYK) layers, and expands any of two Group 4 Fax-compressed bi-level data streams. The two streams are the black layer and a matte for selecting between dither matrices for contone dithering. At the second stage, in parallel with the first, any tags are encoded for later rendering in either IR or black ink.
Finally, in the third stage the contone layer is dithered, and position tags and the bi-level spot layer are composited over the resulting bi-level dithered layer. The data stream is ideally adjusted to create smooth transitions across overlapping segments in the printhead assembly and ideally it is adjusted to compensate for dead nozzles in the printhead assemblies. Up to six channels of bi-level data are produced from this stage.
However, it will be understood that not all of the six channels need be activated. For example, the printhead modules 55 may provide for CMY only, with K pushed into the CMY channels and IR ignored. Alternatively, the position tags may be printed in K if IR ink is not employed. The resultant bi-level CMYK-IR dot-data is buffered and formatted for printing with the integrated circuits of the printhead chips 57 via a set of line buffers (not shown). The majority of these line buffers might be ideally stored on the external DRAM 207. In the final stage, the six channels of bi-level dot data are printed via the PHI 214.
The HC 211 combines the functions of half-toning the contone (typically CMYK) layer to a bi-level version of the same, and compositing the spot1 bi-level layer over the appropriate half-toned contone layer(s). If there is no K ink, the HC 211 functions to map K to CMY dots as appropriate. It also selects between two dither matrices on a pixel-by-pixel basis, based on the corresponding value in the dither matrix select map. The input to the HC 211 is an expanded contone layer (from the JPEG decoder 205) through a buffer 217, an expanded bi-level spot1 layer through a buffer 218, an expanded dither-matrix-select bitmap at typically the same resolution as the contone layer through a buffer 219, and tag data at full dot resolution through a buffer (FIFO) 220.
The HC 211 uses up to two dither matrices, read from the external DRAM 207. The output from the HC 211 to the LLF 213 is a set of printer resolution bi-level image lines in up to six colour planes. Typically, the contone layer is CMYK or CMY, and the bi-level spot1 layer is K. Once started, the HC 211 proceeds until it detects an “end-of-image” condition, or until it is explicitly stopped via a control register (not shown).
The LLF 213 receives dot information from the HC 211, loads the dots for a given print line into appropriate buffer storage (some on integrated circuit (not shown) and some in the external DRAM 207) and formats them into the order required for the integrated circuits of the printhead chips 57. More specifically, the input to the LLF 213 is a set of six 32-bit words and a Data Valid bit, all generated by the HC 211.
As previously described, the physical location of the nozzles 150 on the printhead chips is in two offset rows 151, which means that odd and even dots of the same colour are for two different lines. In addition, there is a number of lines between the dots of one colour and the dots of another. Since the six colour planes for the same dot position are calculated at one time by the HC 211, there is a need to delay the dot data for each of the colour planes until the same dot is positioned under the appropriate colour nozzle. The size of each buffer line depends on the width of the printhead assembly. A single PEC integrated circuit 190 may be employed to generate dots for up to 16 printhead chips 57 and, in such case, a single odd or even buffer line is therefore 16 sets of 640 dots, for a total of 10,240 bits (1280 bytes).
The PHI 214 is the means by which the PEC integrated circuit 190 loads the printhead chips 57 with the dots to be printed, and controls the actual dot printing process. It takes input from the LLF 213 and outputs data to the printhead chips 57. The PHI 214 is capable of dealing with a variety of printhead assembly lengths and formats.
A combined characterization vector of each printhead assembly 50 and 51 can be read back via the serial interface 205. The characterization vector may include dead nozzle information as well as relative printhead module alignment data. Each printhead module can be queried via a low-speed serial bus 221 to return a characterization vector of the printhead module.
The characterization vectors from multiple printhead modules can be combined to construct a nozzle defect list for the entire printhead assembly and allows the PEC integrated circuit 190 to compensate for defective nozzles during printing. As long as the number of defective nozzles is low, the compensation can produce results indistinguishable from those of a printhead assembly with no defective nozzles.
Some of the features of a pagewidth printhead that incorporates the chip and the print engine controller which have been described above are summarized as follows:
It will be understood that the constructional and operating principles of the printer of the present invention may be realised with various embodiments. Thus, variations and modifications may be made in respect of the embodiments as specifically described above by way of example.
This application is a continuation of U.S. application Ser. No. 11/965,703 filed Dec. 27, 2007, which is a continuation application of U.S. patent application Ser. No. 11/003,334 filed on Dec. 6, 2004, now issued U.S. Pat. No. 7,328,968, all of which are herein incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11965703 | Dec 2007 | US |
| Child | 12817179 | US | |
| Parent | 11003334 | Dec 2004 | US |
| Child | 11965703 | US |
