Head wiping mechanism for ink jet printer

Information

  • Patent Grant
  • 6299278
  • Patent Number
    6,299,278
  • Date Filed
    Thursday, February 5, 1998
    26 years ago
  • Date Issued
    Tuesday, October 9, 2001
    23 years ago
Abstract
A printer assembly providing quick and effective wiping of print heads. The printer assembly includes a carriage for holding a print head and having a slide contact, a slide having a wiper ramp, a carriage contact contactable by the slide contact of the carriage, and a wiper assembly including a base, a post extending from the base, a wiper arm, a wiper latch, a wiper holder, and a wiper blade, wherein the wiper arm is connected to the base such that the wiper arm is raised in a case that the wiper arm ramp moves laterally relative to and while in contact with the wiper arm, the wiper latch is connected to the wiper arm such that the wiper latch latches onto the post extending from the base in a case that the wiper arm is sufficiently raised, the wiper holder is connected to the wiper arm, and the wiper blade is connected to the wiper holder.
Description




BACKGROUND OF THE INVENTION




Field of the Invention




The present invention relates to systems for removing excess ink from ink jet print head nozzles. More particularly, the present invention relates to a system for wiping external ink from nozzle opening of an ink jet print head.




Conventional ink jet printers utilize ink jet print heads to print pixels upon a recording medium. Ink jet print heads contain ink jet nozzles which eject ink droplets onto the recording medium through nozzle openings. Over time, ink collects on or near the ink jet nozzle openings, thereby tending to clog the nozzle openings.




Due to the foregoing, many conventional ink jet printers provide systems for cleaning ink from ink jet nozzles before, during, or after printing. One such system is a wiping system, in which an element is moved across ink jet nozzle openings so as to wipe ink from the openings.




In order to clean the ink jet nozzles most effectively, such wiping cannot occur at normal print speeds. Rather, the print head must move in relation to the wiping element at a speed much slower than normal printing speeds. Accordingly, nozzle wiping slows the printing process.




For example, in conventional wiping systems, an ink jet print head is moved out of a printing area to a wiping station. At the wiping station, a wiping element is moved relative to the ink jet print head so as to wipe the nozzles of the ink jet print head, the wiping element is lowered, and printing resumes. Accordingly, what is needed is a system for quickly and effectively wiping ink jet nozzles.




Ink jet nozzle wiping is more problematic in a case of dual-head ink jet printing. Dual-head ink jet printers utilize two ink jet print heads, each print head having a set of ink jet nozzles. In order to provide wiping of each set of nozzles, some dual head printing systems provide one wiper outside of a printing area. Accordingly, such systems are capable of wiping a first print head and then printing with the first print head while wiping the second print head. It should be noted that due to the slow speed at which wiping must occur, printing by the first print head proceeds much slower than in conventional printing.




Accordingly, what is also needed is a system which provides for simultaneous wiping of two ink jet print heads and which causes minimal printing delays.




SUMMARY OF THE INVENTION




The present invention addresses the foregoing problems by providing a wiping system directly triggered by movement of a carriage containing an ink jet print head. As a result, the present invention provides fast nozzle wiping.




In one aspect, the invention is a printer assembly including a carriage, a slide and a wiper assembly. The carriage is for holding a print head and includes a slide contact. The slide includes a wiper ramp and a carriage contact contactable by the slide contact of the carriage. The wiper assembly includes a base, a post extending from the base, a wiper arm, a wiper latch, a wiper holder, and a wiper blade. The wiper arm is connected to the base such that the wiper arm is raised in a case that the wiper arm ramp moves laterally relative to and while in contact with the wiper arm. The wiper latch is connected to the wiper arm such that the wiper latch latches onto the post extending from the base in a case that the wiper arm is sufficiently raised. The wiper holder is connected to the wiper arm, and the wiper blade is connected to the wiper holder.




By virtue of the foregoing arrangement, the printer assembly can quickly and effectively wipe ink jet nozzles of a print head.




Preferably, the carriage includes a wiper latch contact for unlatching the wiper latch during lateral movement of the carriage. Also, in the preferred embodiment, the printer assembly includes a second wiper assembly, the carriage holds a second print head, and the slide has a second wiper arm ramp.




In another aspect, the invention is a wiper assembly including a base, a post extending from the base, a wiper arm connected to the base, a wiper latch connected to the wiper arm, a wiper holder connected to the wiper arm, and a wiper blade connected to the wiper holder. The wiper latch is connected to the wiper arm such that the wiper latch latches onto the post in a case that the wiper arm is sufficiently raised, thereby holding the wiper blade in a raised position.




Preferably, the wiper arm is pivotally connected to the base, and the wiper latch is pivotally connected to the wiper arm. In addition, a latch spring is connected to the base and to the wiper latch such that the latch spring holds the wiper latch against the post and urges the wiper arm downward.




The foregoing wiper assembly arrangement can be used to quickly and effectively wipe ink jet nozzles of a print head before, during and after printing.




In another aspect, the invention is a method of wiping a print head with a wiper blade. The method includes the steps of moving a carriage laterally in a first direction so as to push a slide, raising a wiper arm using a ramp in the slide, thereby raising the wiper blade, and latching a wiper latch to hold the wiper blade at a raised position. The method also includes the steps of moving the carriage laterally in a second direction opposite to the first direction, wiping the print head with the raised wiper blade as the carriage moves in the second direction, unlatching the wiper latch using the carriage, and lowering the wiper blade.




In the preferred embodiment, in a case that the wiper latch is unlatched, the wiper blade is lowered via a latch spring. In addition, the carriage unlatches the wiper latch by pushing the wiper latch during lateral movement.




In a further aspect, the invention is a method of wiping plural print heads with plural wiper blades. The method includes the steps of moving a carriage laterally in a first direction, raising the plural wiper blades, holding the wiper blades at respective raised positions, and wiping each of the print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.




The invention also contemplates a method of wiping plural print heads with plural wiper blades which includes the steps of moving a carriage in a first direction to raise the wiper blades, and wiping each of the plural print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.




In still another aspect, the invention is a method of wiping plural print heads with plural wiper blades. The method includes the steps of moving a carriage laterally in a first direction so as to push a slide, raise plural wiper arms using plural ramps in the slide, thereby raising the plural wiper blades, and latching plural wiper latches to hold the wiper blades at respective raised positions. The method also includes the steps of moving the carriage laterally in a second direction opposite to the first direction, wiping each of the print heads with respective ones of the raised wiper blades as the carriage moves in the second direction, unlatching the wiper latches using the carriage, and lowering the wiper blades.




In the preferred embodiment, when the wiper latches are unlatched, the wiper blades are lowered via latch springs. In addition, the carriage unlatches the wiper latches by pushing the wiper latches.




In yet another aspect, the invention is a method of wiping plural print heads with plural wiper blades. The method includes the step of determining if a predetermined time has elapsed since a last wiping. The method also includes the steps of moving a carriage laterally in a first direction to raise the wiper blades in a case that the predetermined time has elapsed since the last wiping, and wiping each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.




The invention also concerns a method of wiping plural print heads with plural wiper blades including the step of determining if one of plural counters, each of which counts a quantity of ink ejection, has counted to a threshold value. The method also includes the steps of moving a carriage in a first direction to raise the wiper blades in a case that one of the counters has counted to the threshold value, and wiping each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.




In another aspect, the invention is a method of wiping plural print heads with plural wiper blades. The method includes the steps of determining if a predetermined time has elapsed since a last wiping and determining if one of plural counters, each of which counts a quantity of ink ejection, has counted to a threshold value. The method also includes the steps of moving a carriage laterally in a first direction to raise the wiper blades in a case that the predetermined time has elapsed since the last wiping and in a case that one of the counters has counted to the threshold value, and wiping each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.




Advantageously, the foregoing methods provide quick and effective wiping of ink jet nozzles of a print head and thereby increase printing speed.




This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiments thereof in connection with the attached drawings.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

shows a perspective view of computing equipment used in connection with a printer assembly according to the invention.





FIG. 2

is a front, cut-away perspective view of the printer shown in FIG.


1


.





FIG. 3

is a block diagram showing the hardware configuration of a host processor interfaced to a printer having a printer assembly according to the invention.





FIG. 4

is a perspective view of the bottom and rear of a carriage according to the invention.





FIG. 5

, comprising

FIGS. 5A through 5C

, are views of a slide according to the invention.





FIG. 6

, comprising

FIGS. 6A through 6C

, are views of a wiper assembly according to the invention, in a wiper down position.





FIG. 7

, comprising

FIGS. 7A through 7C

, are views of a wiper assembly according to the invention, in a wiper up position.





FIG. 8

is an exploded view of a wiper assembly according to the invention.





FIG. 9

is a flowchart for describing wiping of plural print heads according to the invention.





FIG. 10

is a flowchart for describing a process to wipe plural print heads according to the invention.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS





FIG. 1

is a view showing the outward appearance of computing equipment using connection with the invention described herein. Computing equipment


1


includes host processor


2


. Host processor


2


comprises a personal computer (herein after “PC”), preferably an IBM PC-compatible computer having a windowing environment, such as Microsoft® Windows 95. Provided with computing equipment


1


are display screen


3


comprising a color monitor or the like, keyboard


6


for entering text data and user commands, and pointing device


7


. Pointing device


7


preferably comprises a mouse for pointing to and for manipulating objects displayed on display screen


3


.




Computing equipment 1 includes a computer-readable memory medium, such as fixed computer disk


5


, and floppy disk interface


4


. Floppy disk interface


4


provides a means whereby computing equipment


1


can access information, such as data files, application programs, etc., stored on floppy disks. A similar CD-ROM interface (not shown) may be provided with computing equipment


1


through which computing equipment


1


can access information stored on a CD-ROM.




Disk


5


stores, among other things, application programs by which host processor


2


generates files, manipulates and stores those files on disk


5


, presents data in those files to an operator via display screen


3


, and prints data in those files via printer


10


. Disk


5


also stores an operating system which, as noted above, is preferably a windowing operating system. Device drivers are also stored on disk


5


. At least one of the device drivers comprises a printer driver which provides a software interface to firmware in printer


10


.




In preferred embodiments of the invention, printer


10


is a multi-head serial printer. Accordingly, although the invention described herein is not limited to use with such a printer, the invention will be described in the context of such a printer.




In this regard,

FIG. 2

is a front, cut-away perspective view of printer


10


. As shown in

FIG. 2

, printer


10


is a dual-cartridge printer which prints images using two print heads (i.e., one head per cartridge). Each print head has multiple ink jet nozzles which are used to print data upon a recording medium.




In more detail, cartridges


14




a


and


14




b


each contain a print head and are held in receptacles


12




a


and


12




b


, respectively. Receptacles


12




a


and


12




b


in turn are parts of carriage


11


. Carriage


11


is pulled laterally along bar


16


by belt


17


, which is driven by a carriage motor (not shown). As carriage


11


moves, the ink jet nozzles of the print heads are commanded to eject ink droplets in accordance with print data. Carriage


11


can move both left to right and right to left, providing for dual-directional printing as needed.




Over time, the ink jet nozzles tend to clog. Therefore, the nozzles require intermittent cleaning, such as by the wiping system of the invention.




In response to commands from host processor


2


or commands from internal printer control logic, carriage


11


is moved toward home side


19


of printer


10


, to home position


20


. Carriage


11


is moved to home position


20


, for example, when printer


10


is idle, when printer


10


is turned off, when paper is being ejected from printer


10


, or when the print heads of cartridges


14




a


and


14




b


need to be cleaned.




Disposed at home position


20


so as to clean the print heads are ink suction devices


21




a


and


21




b


, wiper assemblies


22




a


and


22




b


, and ink expulsion receptacles


23




a


and


23




b.






Ink suction devices


21




a


and


21




b


preferably comprise a rotary pump and print head connection caps. The print head connection caps connect to the print heads of cartridges


14




a


and


14




b


during print head cleaning and at other times, such as when printer


10


is powered off, so as to protect the print heads.




Ink expulsion receptacles


23




a


and


23




b


preferably receive ink optionally expelled from the print heads after the print heads are wiped.




Also shown in

FIG. 2

are wiper blades


25




a


and


25




b


and latches


26




a


and


26




b


of wiper assemblies


22




a


and


22




b


. Additionally, slide


28


is shown having carriage contact


29


, which interacts with wiper assemblies


22




a


and


22




b


and carriage


11


during print head wiping operations, as described in more detail below.





FIG. 3

is a block diagram showing the internal functional structure of host processor


2


and printer


10


. In

FIG. 3

, host processor


2


includes a central processing unit


100


such as a programmable microprocessor interfaced to computer bus


101


. Also coupled to computer bus


101


are display interface


102


for interfacing to display


3


, printer interface


104


for interfacing to printer


10


through bi-directional communication line


106


, floppy disk interface


4


for interfacing to floppy disk


107


, keyboard interface


109


for interfacing to keyboard


6


, and pointing device interface


110


for interfacing to pointing device


7


. Disk


5


includes an operating system section for storing operating system


111


, an applications section for storing application files


112


, and a printer driver section for storing printer driver


114


.




A random access main memory (hereinafter “RAM”)


116


interfaces to computer bus


101


to provide CPU


100


with access to memory storage. In particular, when executing stored computer-executable process steps such as those associated with application files


112


, CPU


100


loads those application instruction sequences from disk


5


(or other storage media such as media accessed via a network or floppy disk interface


4


) into RAM


116


and executes those stored program instruction sequences out of RAM


116


. RAM


116


provides for a print data buffer used by printer driver


114


. It should also be recognized that standard disk-swapping techniques available under the windowing operating system allow segments of memory, including the aforementioned print data buffer, to be swapped on and off of disk


5


.




Read only memory (hereinafter “ROM”)


103


in host processor


2


stores invariant instruction sequences, such as start-up instruction sequences or basic input/output operating system (BIOS) sequences for operation of keyboard


6


.




As shown in

FIG. 3

, and as previously mentioned, disk


5


stores program instruction sequences for a windowing operating system and for various application programs such as graphics application programs, drawing application programs, desktop publishing application programs, and the like. In addition, disk


5


also stores color image files such as might be displayed by display


3


or printed by printer


10


under control of a designated application program. Disk


5


also stores a color monitor driver in other drivers section


119


which controls how multi-level RGB color primary values are provided to display interface


102


. Printer driver


114


controls printer


10


for both black/white and color printing and supplies print data for printout according to the configuration of printer


10


. Print data is transferred to printer


10


, and control signals are exchanged between host processor


2


and printer


10


, through printer interface


104


connected to line


106


under control of printer driver


114


. Other device drivers are also stored on disk


5


for providing appropriate signals to various devices, such as network devices, facsimile devices, and the like, connected to host processor


2


.




Printer


10


includes CPU


121


such as an 8-bit or a 16-bit microprocessor, ROM


122


, control logic


124


, and I/O ports unit


127


connected to bus


126


. Also connected to control logic


124


is RAM


129


. Control logic


124


includes controllers for line feed motor


131


, for carriage motor


132


, for print image buffer storage in RAM


129


, for heat pulse generation, and for print head data. Control logic


124


also provides control signals and print data for print heads


15




a


and


15




b


of print engine


130


.




I/O ports unit


127


is coupled to print engine


130


. In print engine


130


, print heads


15




a


and


15




b


perform recording on a recording medium by scanning across the recording medium while printing using print data from a print buffer in RAM


129


. Control logic


124


is also coupled to printer interface


104


of host processor


2


via communication line


106


for exchange of control signals and to receive print data and print data addresses. ROM


122


stores font data, program instruction sequences used to control printer


10


, and other invariant data for printer operation. RAM


129


stores print data in a print buffer defined by printer driver


114


and other information for printer operation.




Although

FIG. 3

shows individual components of printer


10


as separate and distinct from one another, it ig preferable that some of the components be combined. For example, control logic


124


may be combined with I/O ports


127


in an ASIC to simplify interconnections for the functions of printer


10


.




The structure and operation of printer


10


used for cleaning print heads is described below.




Briefly, a printer assembly according to the invention includes a carriage, a slide, and a wiper assembly. The carriage is for holding a print head and includes a slide contact. The slide includes a wiper ramp and a carriage contact contactable by the slide contact of the carriage. The wiper assembly includes a base, a post extending from the base, a wiper arm, a wiper latch, a wiper holder, and a wiper blade. The wiper arm is connected to the base such that the wiper arm is raised in a case that the wiper arm ramp moves laterally relative to and while in contact with the wiper arm. The wiper latch is connected to the wiper arm such that the wiper latch latches onto the post in a case that the wiper arm is sufficiently raised. The wiper holder is connected to the wiper arm, and the wiper blade is connected to the wiper holder. In the preferred embodiment described below, the printer assembly includes a second wiper assembly, the carriage holds a second print head and the slide has a second wiper arm ramp.





FIG. 4

is a perspective view of the bottom and rear of a carriage according to the invention. Due to the orientation of

FIG. 4

, home side


19


is located to the left of the figure.




Carriage


11


has two receptacles


12




a


and


12




b


for holding cartridges


14




a


and


14




b


. At the bottom of cartridges


14




a


and


14




b


are print heads


15




a


and


15




b


. cartridges


14




a


and


14




b


can be removed from receptacles


12




a


and


12




b


for replacement or repair.




Disposed near the bottom of carriage


11


is slide contact


31


. This contact is preferably a small protrusion extending from the rear of carriage


11


. In the preferred embodiment, slide contact


31


is near the side of carriage


11


that is closest to home side


19


. As carriage


11


moves towards home position


20


, slide contact


31


of carriage


11


encounters and pushes carriage contact


29


of slide


28


.




Ledges


32




a


and


32




b


are disposed on the bottom of carriage


11


, one corresponding to each of print heads


15




a


and


15




b


. The ledges are disposed near to the rear of carriage


11


, parallel to the direction of carriage movement and substantially adjacent to print heads


15




a


and


15




b


. Each of ledges


32




a


and


32




b


serves to push against a wiper assembly spacer, discussed below, so as to ensure that only desired portions of wiper blades


25




a


and


25




b


encounter print heads


15




a


and


15




b.






Wiper latch grooves


34




a


and


34




b


are also disposed near the rear of carriage


11


and parallel to the direction of carriage movement on the bottom of carriage


11


. Wiper latch grooves


34




a


and


34




b


provide clearance for wiper latches


26




a


and


26




b


of the wiper assemblies, discussed below, so as to allow carriage


11


to move relative to wiper latches


26




a


and


26




b


for some distance without causing latches


26




a


and


26




b


to unlatch.




Wiper latch contacts


35




a


and


35




b


are disposed at the ends of grooves


34




a


and


34




b


, respectively, which are closest to home side


19


. Contacts


35




a


and


35




b


close off wiper latch grooves


34




a


and


34




b


. Wiper latch contacts


35




a


and


35




b


push and thereby unlatch latched wiper latches


26




a


and


26




b


in a manner discussed below.





FIGS. 5A through 5C

are views of a slide according to the invention.

FIG. 5A

is a front view,

FIG. 5B

is a top view and

FIG. 5C

is an end view of the slide.




Slide


28


is disposed near home position


20


in printer


10


. Support posts


39


extend from the top of slide


28


. Surmounting support posts


39


are support ledges


40


, which sit on top of an interior surface (not shown) in printer


10


. The remainder of slide


28


hangs below the interior surface. A slot in the surface accommodates support posts


39


, allowing the slide to move laterally within printer


10


.




Extending from support ledge


40


that is closest to home side


19


is carriage contact


29


. As mentioned above, when carriage


11


moves towards home position


20


, slide contact


31


of carriage


11


encounters and pushes carriage contact


29


of slide


28


, thereby urging slide


28


in the direction of home side


19


.




Spring post


41


extends from the rear of slide


28


. Spring post


41


is connected to slide spring


42


, which extends away from home side


19


so as to resist motion of slide


28


as slide


28


is pushed by slide contact


31


of carriage


11


toward home side


19


.




Wiper arm ramps


43




a


and


43




b


, corresponding to print heads


15




a


and


15




b


, respectively, are disposed on the front of slide


28


. Each wiper arm ramp slopes upward such that as slide


28


moves laterally toward home side


19


of printer


10


, wiper arms (shown in

FIGS. 6A

to


6


C,


7


A to


7


C, and


8


) which are in contact with wiper arm ramps


43




a


and


43




b


are urged upward. Thus, slide


28


serves to translate the lateral movement of carriage


11


toward home position


20


into an upward movement of wiper arms contacting slide


28


at wiper arm ramps


43




a


and


43




b.






The structure of wiper assembly


22




a


is discussed below. Briefly, a wiper assembly according to the invention includes a base, a post extending from the base, a wiper arm connected to the base, a wiper latch connected to the wiper arm such that the wiper latch latches onto the post extending from the base in a case that the wiper arm is sufficiently raised, a wiper holder connected to the wiper arm, and a wiper blade connected to the wiper holder, such that the wiper blade is raised to a raised position in a case that the wiper arm is raised.




Preferably, the wiper arm is pivotally connected to the base, and the wiper latch is pivotally connected to the wiper arm. Additionally, in the preferred embodiment, the wiper assembly includes a latch spring and a blade spring. The latch spring is connected to the base and to the wiper latch such that the latch spring holds the wiper latch against the post and urges the wiper arm downward. The wiper holder is connected to the wiper arm via the blade spring. Also, the wiper holder preferably includes a wiper spacer that extends past the top of the wiper blade.




In this regard,

FIGS. 6A

to


6


C show wiper assembly


22




a


in a wiper-down position and including wiper blade


25




a


and latch


26




a


of FIG.


2


.

FIG. 6A

is a front view,

FIG. 6B

is a top view, and

FIG. 6C

is an end view of wiper assembly


22




a


in the wiper-down position. It should be noted that a second, substantially similar wiper assembly is provided in printer


10


and includes wiper blade


25




b


and latch


26




b


of FIG.


2


.




Wiper assembly


22




a


includes wiper base


47


. Wiper base


47


has three protrusions extending vertically therefrom. Two of these protrusions are supports


48


and


49


, which hold wiper assembly


22




a


in printer


10


. The third protrusion is post


50


, which is disposed between supports


48


and


49


. In the preferred embodiment, base


47


also includes ink expulsion receptacle


23




a


. As shown, ink expulsion receptacle


23




a


is a hollow rectangular passage through base


47


. In addition, in the preferred embodiment, base


47


is made from a suitable material such as plastic.




Wiper assembly


22




a


also includes wiper arm


53


, which extends from inside of support


48


, across wiper assembly


22




a


and past support


49


. Wiper arm


53


includes tab


60


extending therefrom which, when wiper assembly


22




a


is positioned in printer


10


, rests on wiper arm ramp


43




a


of slide


28


. Thus, when slide


28


moves laterally toward home side


19


of printer


10


, tab


60


extending from wiper arm


53


is urged upward by wiper arm ramp


43




a


. Wiper arm


53


is connected to wiper base


47


such that wiper arm


53


is raised in response to the upward motion of tab


60


.




In the preferred embodiment, wiper arm


53


is pivotally connected to wiper base


47


at wiper arm pivot


54


via arms


55


. Thus, wiper arm


53


is not raised in a linear manner when tab


60


of wiper arm


53


is urged upward by wiper arm ramp


43




a


. Instead, wiper arm


53


rotates around wiper arm pivot


54


, which is positioned such that the resulting motion of wiper arm


53


is generally upward.




Wiper latch


26




a


is connected to wiper arm


53


such that wiper latch


26




a


latches onto post


50


in a case that wiper arm


53


is sufficiently raised. Overhang


61


extends from the top of wiper latch


26




a


. In the preferred embodiment, latch spring


56


is disposed go as to hold wiper latch


26




a


against post


50


and to hold wiper latch


26




a


onto the top of post


50


once wiper latch


26




a


is latched to post


50


. Thus, as wiper arm


53


is raised, wiper latch


26




a


is pressed against post


50


by latch spring


56


. Once overhang


61


of wiper latch


26




a


moves vertically past post


50


, overhang


61


is urged onto the top of post


50


by latch spring


56


, thereby latching wiper latch


26




a


onto post


50


. If wiper latch


26




a


latches onto post


50


, wiper arm


53


remains raised even if no longer urged upward.




In the preferred embodiment, latch spring


56


also urges latch


26




a


downward. In this regard, wiper latch


26




a


preferably is pivotally connected to wiper arm


53


at wiper latch pivot


57


. Thus, latch spring


56


also urges wiper arm


53


downward. Accordingly, once wiper latch


26




a


is unlatched from post


50


, latch spring


56


lowers wiper arm


53


.




Wiper assembly


22




a


also includes wiper holder


58


connected to wiper arm


53


by blade spring


62


. Wiper holder


58


is preferably pivotally connected to wiper base


47


at wiper arm pivots


54


via arms


59


. Thug, wiper holder


56


moves concentrically with wiper arm


53


such that if wiper arm


53


is raised, wiper holder


58


is also raised.




Wiper blade


25




a


is attached to wiper holder


58


. Accordingly, when wiper holder


58


is raised, wiper blade


25




a


is also raised. Therefore, when wiper arm


53


is raised, wiper blade


25




a


is raised.




Wiper blade


25




a


is preferably made from a material suitable for wiping a print head. As print heads are typically somewhat delicate, a soft rubber or plastic is suitable for use as wiper blade


25




a.






Wiper spacer


64


extends vertically from wiper holder


58


past the top of wiper blade


25




a


. Wiper spacer


64


functions in conjunction with ledge


32




a


of carriage


11


so as to ensure that only a desired portion of wiper blade


25




a


comes into contact with print head


15




a


during wiping.




It should be noted that the portion of wiper blade


25




a


that contacts print head


15




a


during wiping is determined by the physical interrelationship of ledge


32




a


, wiper blade


25




a


, and spacer


64


. Accordingly, ledge


32




a


, wiper blade


25




a


, and spacer


64


should be configured so that the exposed surfaces of ink jet nozzles of print head


15




a


are wiped using at least the top edge of wiper blade


25




a.







FIGS. 7A

to


7


C show wiper assembly


22




a


according to the invention, in a wiper-up position.

FIG. 7A

is a front view,

FIG. 7B

is a top view, and

FIG. 7C

is an end view of wiper assembly


22




a


in the wiper-up position.




In order to achieve the wiper-up position according to the invention, wiper arm


53


is raised by wiper arm ramp


43




a


, thereby raising wiper latch


26




a


until overhang


61


latches onto post


50


. Wiper arm


53


also raises wiper holder


58


, which raises wiper blade


25




a


. Because wiper latch


26




a


is latched onto post


50


, wiper arm


53


and thus wiper holder


58


and wiper blade


25




a


remain in the wiper-up position until wiper latch


26




a


is unlatched from post


50


. Wiper latch


26




a


can be unlatched from post


50


by being pushed such that overhang


61


of wiper latch


26




a


is no longer over the top of post


50


. In the preferred embodiment, wiper latch contact


35




a


of carriage


11


pushes wiper latch


26




a


after carriage


11


moves print head


15




a


past raised wiper blade


15




a.






In order to more clearly illustrate a wiper assembly according to the invention,

FIG. 8

shows an exploded view of wiper assembly


22




a


of

FIGS. 6 and 7

. Illustrated in

FIG. 8

is wiper base


47


, wiper arm


53


, wiper latch


26




a


, wiper holder


58


, and wiper blade


25




a


. Wiper base


47


is shown having ink expulsion receptacle


23




a


, supports


48


and


49


, and post


50


. Wiper arm


53


is also shown having tab


60


, arms


55


, wiper arm pivots


54


, and wiper latch pivot


57


. Moreover, wiper latch


26




a


is shown having overhang


61


and wiper holder


58


is shown having wiper blade


25




a


, arms


59


and wiper spacer


64


. Also shown are latch spring


56


and blade spring


62


.




In operation, in a case that one or both of print heads


15




a


and


15




b


in carriage


11


needs to be cleaned, carriage motor


132


drives belt


17


so as to move carriage


11


to home position


20


. As carriage


11


moves into home position


20


, wiper blades


25




a


and


25




b


of wiper assemblies


22




a


and


22




b


are raised to the wiper-up position, as discussed in more detail below. When carriage


11


reaches home position


20


, ink suction devices


21




a


and


21




b


optionally suction ink from print heads


15




a


and


15




b


so as to clear the nozzles of print heads


15




a


and


15




b


. Next, the carriage motor is actuated so as to move carriage


11


from home position


20


, away from home side


19


of printer


10


. As carriage


11


moves, print heads


15




a


and


15




b


pass across raised wiper blades


25




a


and


25




b


, respectively. Wiper blades


25




a


and


25




b


wipe excess ink from print heads


15




a


and


15




b


. After print heads


15




a


and


15




b


have been wiped, wiper blades


25




a


and


25




b


are lowered, as discussed below in more detail.




The operation of the wiper assemblies in raising the wiper blades, wiping the print heads, and lowering the wiper blades is discussed in more detail below with respect to FIG.


9


.




Briefly, such an operation includes the steps of moving a carriage laterally in a fixed direction so a to push a slide, raising plural wiper arms using plural ramps in the slide, thereby raising the wiper blades, and latching plural wiper latches to hold the wiper blades at respective raised positions. The method also includes the steps of moving the carriage laterally in a second direction opposite to the first direction, wiping each of the print heads with a respective one of the raised wiper blades as the carriage moves in the second direction, unlatching the wiper latches using the carriage, and lowering the wiper blades.




It should be noted that in the following discussion, a letter “a” appended to a reference numeral indicates an element associated with wiper assembly


22




a


, and a letter “b” appended to a reference numeral indicates an element associated with wiper assembly


22




b


. The reference numerals themselves correspond to the reference numerals in the above discussion of

FIGS. 6

,


7


and


8


. For example, wiper holders


58




a


and


58




b


have the same construction and function as wiper holder


58


discussed above and correspond respectively to wiper assemblies


22




a


and


22




b.






In step S


901


, carriage


11


moves laterally in a first direction towards home position


20


. As carriage


11


moves, slide contact


31


of carriage


11


comes into contact with carriage contact


29


of slide


28


, thereby pushing slide


28


toward home side


19


of printer


10


.




In step S


902


, wiper arm ramps


43




a


and


43




b


raise wiper arms


53




a


and


53




b


, respectively. As described above, the raising of wiper arms


53




a


and


53




b


raises wiper holders


58




a


and


58




b


, as well as wiper blades


25




a


and


25




b.






Ramps


43




a


and


43




b


are preferably disposed with respect to wiper arms


53




a


and


53




b


such that a wiper blade is raised after being passed over by print heads having a home position closer to home side


19


than the wiper blade. For example, in the preferred embodiment, wiper blade


25




a


is not raised until print head


15




b


has passed over wiper blade


25




a.






In step S


903


, wiper latches


26




a


and


26




b


, which also raise in response to the raising of wiper arms


53




a


and


53




b


, latch onto posts


50




a


and


50




b


using overhangs


61




a


and


61




b


and wiper latch springs


56




a


and


56




b.






In step S


904


, carriage


11


moves laterally away from home position


20


. Therefore, carriage


11


moves in step S


904


in a direction opposite to the direction in which carriage


11


moved in step S


901


.




In step S


905


, as carriage


11


moves away from home position


20


, print heads


15




a


and


15




b


are wiped by wiper blades


25




a


and


25




b


, respectively. Wiping in step S


905


preferably occurs simultaneously so as to shorten an amount of time needed to perform wiping. As each of print heads


15




a


and


15




b


passes its respective wiper blade


25




a


and


25




b


, ledges


32




a


and


32




b


of carriage


11


come into contact with spacers


64




a


and


64




b


, respectively. During this contact, wiper holders


58




a


and


58




b


and spacers


64




a


and


64




b


are urged upward by blade springs


62




a


and


62




b


, respectively, thereby pressing spacers


64




a


and


64




b


against ledges


32




a


and


32




b


, respectively. The urging of wiper holders


58




a


and


58




b


ensures firm contact between wiper blades


25




a


and


25




b


and print heads


15




a


and


15




b


, respectively. Simultaneously, contact between ledges


32




a


and


32




b


and spacers


64




a


and


64




b


ensures that only desired portions of wiper blades


25




a


and


25




b


come into contact with print heads


15




a


and


15




b


, respectively.




During step S


905


, wiper latches


26




a


and


26




b


are latched so as to keep wiper blades


25




a


and


25




b


in raised positions. In order to prevent carriage


11


from unlatching wiper latches


26




a


and


26




b


, wiper latches


26




a


and


26




b


move within wiper latch grooves


34




a


and


34




b


, respectively.




In step S


906


, carriage


11


unlatches wiper latches


26




a


and


26




b


. In step S


906


, respective ones of wiper latch contacts


35




a


and


35




b


contact wiper latches


26




a


and


26




b


after wiper latches


26




a


and


26




b


have moved through wiper latch grooves


34




a


and


34




b


, respectively. Accordingly, wiper latch contact


35




a


pushes wiper latch


26




a


off of post


50




a


, and wiper latch contact


35




b


pushes wiper latch


26




b


off of post


50




b


. Advantageously, wiper latch contact


35




a


unlatches wiper latch


26




a


before print head


15




b


passes wiper blade


25




a


. Accordingly, print head


15




b


is wiped only by wiper blade


25




b.






In step S


907


, wiper blades


25




a


and


25




b


are lowered in response to the unlatching of wiper latches


26




a


and


26




b


. In the preferred embodiment, wiper blades


25




a


and


25




b


are lowered by the urging of wiper arms


53




a


and


53




b


downward by latch springs


56




a


and


56




b.






By virtue of the foregoing structure and operation, plural print heads can be simultaneously, quickly and effectively wiped.





FIG. 10

is a flowchart for describing computer-executable process steps to wipe plural print heads according to the invention. The process steps are preferably embodied in printer driver


114


stored on disk


5


and executed by CPU


100


. Of course, the process steps may be obtained from a source other than printer driver


114


and may also be executed by CPU


121


or by both CPU


100


and CPU


121


.




Briefly, the process steps include a step to determine if a predetermined time has elapsed since a last wiping and to determine if one of plural counters, each of which counts a quantity of ink ejection, has counted to a threshold value. The process steps also include a step to move a carriage laterally in a first direction to raise wiper blades in a case that the predetermined time has elapsed since the last wiping or in a case that one of the counters has counted to the threshold value, and a step to wipe each of the print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.




In more detail, the above steps may use a timer and a counter or counters. Such a timer or counter(s) may be located in host processor


2


or printer


10


. Alternatively, a general purpose timer or counter(s), such as circuitry found in CPU


100


, may also be used. Preferably, the timer and counter(s) are part of control logic


124


or are emulated in software executed by CPU


100


.




Referring to

FIG. 10

, step S


1001


is reached once printing begins. In step S


1001


, it is determined if a predetermined threshold time has elapsed since a last wiping operation. In the preferred embodiment, a timer measures the elapsed time since the last wiping operation by resetting after each wiping operation. If the timer indicates that the threshold time has elapsed, flow proceeds to step S


1003


; if not, flow proceeds to step S


1002


.




In step S


1002


, it is determined if a droplet counter has counted to a predetermined threshold value. Similarly to the above-described timer, a droplet counter counts an amount of ink ejection since a last wiping by resetting after each wiping. If a droplet counter has counted to the threshold value, flow proceeds to step S


1003


; if not, flow returns to step S


1001


.




In the preferred embodiment, plural droplet counters are used, one for each of print heads


15




a


and


15




b


. In this case, each droplet counter counts the number of ink droplets ejected from the corresponding print head since a last wiping. Alternatively, a single counter can be used to count the total number of ink droplets ejected from all print heads. In the alternative case, the predetermined threshold value will likely be approximately twice the value of values used in the preferred embodiment.




The thresholds used in steps S


1001


and S


1002


can be fixed for use with any type of print head. For example, the threshold time can be fixed at sixty seconds, and the threshold value can be fixed at 6 million droplets. However, in preferred embodiments, the thresholds depend on the type of print heads used during printing. Table I shows some examples of Canon™ ink jet print heads and their corresponding threshold values.












TABLE I











Examples of Droplet and Time Thresholds


















Threshold




Threshold







Print Head




Nozzle




Value




Time











BC-21,




Black




6 million




60 seconds







BC-22,







BC-21e, or




Color




1.5 million




60 seconds







BC-22e







BC-20 or




Black




25 million




60 seconds







BC-23















Although all threshold times are equal in Table I, this need not be the case. Preferably, if two print heads are used, each corresponding to different threshold times, the shorter threshold time is used in step S


1001


.




It should be noted that the order of steps S


1001


and S


1002


can be interchanged. In addition, in alternative embodiments, only one of steps S


1001


or S


1002


is used to determine whether or not wiping is appropriate. For example, in an alternative embodiment, the occurrence of wiping operations is determined solely by a droplet counter.




In step S


1003


, a print head wiping operation is performed. This wiping operation preferably proceeds as explained above with respect to

FIGS. 1

to


9


. After wiping, flow proceeds to step S


1004


, where the timer and the counter(s) are reset. Flow then returns to step S


1001


.




By virtue of the above operation, the invention provides wiping of plural print heads at appropriate moments during printing.




While the present invention is described above with respect to what is currently considered its preferred embodiments, it is to be understood that the invention is not limited to that described above. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.



Claims
  • 1. A printer assembly comprising:a carriage for holding a print head, the carriage including a slide contact; a slide including a wiper arm ramp and a carriage contact contactable by the slide contact of the carriage; and a wiper assembly including a base, a post extending from the base, a wiper arm connected to the base such that the wiper arm is raised in a case that the wiper arm ramp moves laterally relative to the wiper arm while in contact with the wiper arm, a wiper latch connected to the wiper arm such that the wiper latch latches onto the post extending from the base in a case that the wiper arm is sufficiently raised, a wiper holder connected to the wiper arm, and a wiper blade connected to the wiper holder.
  • 2. The printer assembly of claim 1, wherein the wiper arm is pivotally connected to the base.
  • 3. The printer assembly of claim 1, wherein the wiper latch is pivotally connected to the wiper arm.
  • 4. The printer assembly of claim 1, wherein the carriage further includes a wiper latch contact for unlatching the wiper latch during lateral movement of the carriage.
  • 5. The printer assembly of claim 4, wherein the wiper assembly further includes a latch spring connected to the base and to the wiper latch for holding the wiper latch against the post and for urging the wiper arm downward.
  • 6. The printer assembly of claim 1, wherein the wiper assembly further includes a blade spring and wherein the wiper holder is connected to the wiper arm via the blade spring.
  • 7. The printer assembly of claim 1, wherein the wiper assembly further includes a wiper spacer connected to the wiper holder such that the wiper spacer extends vertically past the wiper blade.
  • 8. The printer assembly of claim 1, further comprising a second wiper assembly, wherein the carriage holds a second print head and the slide has a second wiper arm ramp.
  • 9. The printer assembly of claim 1, wherein the base of the wiper assembly includes an ink expulsion receptacle.
  • 10. A wiper assembly comprising:a base; a post extending from the base; a wiper arm connected to the base; a wiper latch connected to the wiper arm such that the wiper latch latches onto the post extending from the base in a case that the wiper arm is sufficiently raised; a wiper holder connected to the wiper arm; and a wiper blade connected to the wiper holder, wherein the wiper blade is raised in a case that the wiper arm is raised.
  • 11. The wiper assembly of claim 10, wherein the wiper arm is pivotally connected to the base.
  • 12. The wiper assembly of claim 10, wherein the wiper latch is pivotally connected to the wiper arm.
  • 13. The wiper assembly of claim 10, further comprising a latch spring connected to the base and to the wiper latch such that the latch spring holds the wiper latch against the post and urges the wiper arm downward.
  • 14. The wiper assembly of claim 10, further comprising a blade spring, wherein the wiper holder is connected to the wiper arm via the blade spring.
  • 15. The wiper assembly of claim 10, wherein the wiper holder further comprises a wiper spacer that extends vertically past the wiper blade.
  • 16. The wiper assembly of claim 10, wherein the base further includes an ink expulsion receptacle.
  • 17. A method of wiping a print head with a wiper blade, the wiper blade being raisable by a wiper arm of a wiper assembly having a base, comprising the steps of:moving a carriage laterally in a first direction so as to push a slide; raising a wiper arm using a ramp in the slide, thereby raising the wiper blade; latching a wiper latch onto a post extending from the base of the wiper assembly to hold the wiper blade at a raised position; moving the carriage laterally in a second direction opposite to the first direction; wiping the print head with the raised wiper blade as the carriage moves in the second direction; unlatching the wiper latch using the carriage; and lowering the wiper blade.
  • 18. The method of claim 17, wherein the wiper arm pivots upward when raised.
  • 19. The method of claim 17, wherein the wiper blade is lowered via a latch spring.
  • 20. The method of claim 17, wherein the carriage unlatches the wiper latch by pushing the wiper latch.
  • 21. A method of wiping plural print heads with plural wiper blades, comprising the steps of:moving a carriage laterally in a first direction so as to push a slide having plural wiper arm ramps; raising the plural wiper blades by raising plural wiper arms using the plural wiper arm ramps; holding the wiper blades at respective raised positions; and wiping each of the print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.
  • 22. The method of claim 21, wherein the wiper arms pivot upward when raised.
  • 23. The method of claim 21, wherein the wiper blades are held at the respective raised positions via plural wiper latches, and further comprising the step of lowering each wiper blade via a latch spring.
  • 24. The method of claim 23, further comprising the step of unlatching the wiper latches by pushing the wiper latches with the carriage.
  • 25. A method of wiping plural print heads with plural wiper blades, comprising the steps of:moving a carriage in a first direction to raise the plural wiper blades; latching plural wiper latches onto plural posts, each of the plural posts extending from the base of a respective one of plural wiper assemblies, thereby holding the wiper blades at respective raised positions; and wiping each of the plural print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.
  • 26. A method of wiping plural print heads with plural wiper blades, comprising the steps of:determining if one of plural predetermined times has elapsed since a last wiping, each of the predetermined times corresponding to a respective print head, wherein each of the plural predetermined times are concurrently monitored; moving a carriage laterally in a first direction to raise the wiper blades in a case that at least one of the plural predetermined times has elapsed since the last wiping; and wiping each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.
  • 27. The method of claim 26, wherein each of the plural predetermined times corresponds to a type of print head.
  • 28. A method of wiping plural print heads with plural wiper blades, comprising the steps of:determining if one of plural counters, each of which counts a quantity of ink ejection from a corresponding print head, has counted to a threshold value, wherein each of the plural counters are concurrently monitored; moving a carriage in a first direction to raise the plural wiper blades in a case that one of the counters has counted to the threshold value; wiping each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.
  • 29. The method of claim 28, wherein the threshold value depends on the type of print head used during printing.
  • 30. A method of wiping plural print heads with plural wiper blades, comprising the steps of:determining if one of plural predetermined times has elapsed since a last wiping, each of the predetermined times corresponding to a respective print head, wherein each of the plural predetermined times are concurrently monitored; determining if one of plural counters, each of which counts a quantity of ink ejection from a corresponding print head, has counted to a threshold value, wherein each of the plural counters are concurrently monitored; moving a carriage laterally in a first direction to raise the wiper blades in a case that at least one of the plural predetermined times has elapsed since the last wiping or in a case that one of the counters has counted to the threshold value; and wiping each of the print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.
  • 31. The method of claim 30, wherein each of the plural predetermined times corresponds to a type of print head.
  • 32. The method of claim 30, wherein the threshold value depends on the type of print head used during printing.
  • 33. A method of wiping plural print heads with plural wiper blades, the wiper blades being respectively raisable by plural wiper arms, each wiper arm being in a respective wiper assembly having a base, comprising the steps of:moving a carriage laterally in a first direction so as to push a slide; raising plural wiper arms using plural ramps in the slide, thereby raising the wiper blades; latching each of plural wiper latches onto a post extending from the base of the respective wiper assembly to hold the wiper blades at respective raised positions; moving the carriage laterally in a second direction opposite to the first direction; wiping each of the print heads with a respective one of the raised wiper blades as the carriage moves in the second direction; unlatching the wiper latches using the carriage; and lowering the wiper blades.
  • 34. The method of claim 33, wherein the wiper arms pivot upward when raised.
  • 35. The method of claim 33, wherein each wiper blade is lowered via a latch spring.
  • 36. The method of claim 33, wherein the carriage unlatches the wiper latches by pushing the wiper latches.
  • 37. A computer-readable memory medium storing computer-executable process steps to wipe plural print heads with plural wiper blades, the steps comprising:a determining step to determine if one of plural predetermined times has elapsed since a last wiping, each of the predetermined times corresponding to a respective print head, wherein each of the plural predetermined times are concurrently monitored; a moving step to move a carriage laterally in a first direction to raise the wiper blades in a case that at least one of the plural predetermined times has elapsed since the last wiping; and a wiping step to wipe each of the print heads with a respective one of the raised wiper blades as the carriage moves in a second direction opposite to the first direction.
  • 38. The computer-readable memory medium of claim 37, wherein each of the plural predetermined times corresponds to a type of print head.
  • 39. A computer-readable memory medium storing computer-executable process steps to wipe plural print heads with plural wiper blades, the steps comprising:a determining step to determine if one of plural counters, each of which counts a quantity of ink ejection from a corresponding print head, has counted to a threshold value, wherein each of the plural counters are concurrently monitored; a moving step to move a carriage in a first direction to raise the plural wiper blades in a case that one of the counters has counted to the threshold value; and a wiping step to wipe each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.
  • 40. The computer-readable memory medium of claim 39, wherein the threshold value depends on the type of print head used during printing.
  • 41. A computer-readable memory medium storing computer-executable process steps to wipe plural print heads with plural wiper blades, the steps comprising:a determining step to determine if one of plural predetermined times has elapsed since a last wiping, each of the predetermined times corresponding to a respective print head, wherein each of the plural predetermined times are concurrently monitored; a determining step to determine if one of plural counters, each of which counts a quantity of ink ejection from a corresponding print head, has counted to a threshold value, wherein each of the plural counters are concurrently monitored; a moving step to move a carriage laterally in a first direction to raise the wiper blades in a case that at least one of the plural predetermined times has elapsed since the last wiping or in a case that one of the counters has counted to the threshold value; and a wiping step to wipe each of the print heads with a respective one of the raised wiper blades as the carriages moves in a second direction opposite to the first direction.
  • 42. The computer-readable memory medium of claim 41, wherein each of the plural predetermined times corresponds to a type of print head.
  • 43. The computer-readable memory medium of claim 41, wherein the threshold value depends on the type of print head used during printing.
US Referenced Citations (7)
Number Name Date Kind
5103244 Gast et al. Apr 1992
5440331 Grange Aug 1995
5500660 Childers et al. Mar 1996
5565898 Sakuma Oct 1996
5745133 Hendricks et al. Apr 1998
5793388 Martinson et al. Aug 1998
5917517 Kida et al. Jun 1999
Foreign Referenced Citations (1)
Number Date Country
0 698 495 Feb 1996 EP