United States Patent
`
`[19]
`
`[11] Patent Number:
`
`5,682,186
`
`Bohorquez et al.
`
`[45] Date of Patent:
`
`Oct. 28, 1997
`
`USO05682l86A
`
`[54] PROTECTIVE CAPPING APPARATUS FOR
`AN ]N](.]E1' [DEN
`
`4,970,535
`5,027,134
`5,051,761 .
`
`ll/1990 Oswald et al.
`6/1991
`9/1991
`
`........
`
`.. ...... 347/25
`347/29
`347/30
`
`Inventors: Jaime H. Bohorquez, Escondido;
`Charles E. Schinner, San Diego, both
`of Calif.; John H. Dion, Corvallis,
`.
`OWE-9 -‘"34"’ 3- Ema C°“’a“15=
`Ores-: Niels J~ Niel-Sena C°FVa11iS« 0feS~
`.
`Assigneer Hewlett-Packard C0mpanY,Pa1oA1l0,
`-
`
`App]. No.: 209,091
`_
`Ffled:
`
`Man 10. 1994
`
`5
`
`'
`...................................................... B411 21165
`............................... .. 347/29; 347/33; 347/44',
`347/50; 347/87
`Field of Search .................................. 347/29, 44, 31,
`347/33’ 49’ 50’ 37
`
`"
`’
`347'“
`5'19”
`51214/447
`347/44 x
`2/1994
`5,289,213
`347/31
`s/1994
`5,343,230
`347/24
`..
`5,363,132 11/1994
`347/33
`'
`5,394,173 M995
`.......................... 347/37
`5,444,474
`s/1995 Ohtsubo etal.
`FOREIGN PATENT DOCU1VIEN'TS
`
`'
`
`7/1990 European Pat. 011.
`379l51A3
`9/1990 European Pat. on.
`0413323
`1/1992
`.
`.
`0495491
`5/1994
`.
`.
`0627317
`6,1976
`2457643
`U_32o5425 10/1935
`61—233544 10/1986
`67-113550
`5/1937
`1-291947
`11/1989
`0245156
`2/1990
`
`......... B41] 2/165
`.
`13411 21165
`B41] W175
`
`Int. Cl.
`US. Cl.
`
`fiefemees Cited
`
`OTHER PUBLICATIONS
`
`U-5' PAEENT D S
`4/1976 Wnmebei-1 et al.
`..................... 401/217
`3,951,555
`ifiggg fig’;
`1- :----
`__
`::iZ}:g;1)
`1/1935 Teiasawa
`...... 347/30
`4,492,969
`9/1985 Terasawa .
`4,543,589
`.................................. 347/49
`3/1986 Rix et al.
`4,577,200
`6/1936 Dennese et a1.
`101/'38-1
`4.592.277
`2’1937 5him°53‘° 9131-
`-- 347/44
`4-545-111
`3/1937 Naka ............. ..
`.. 347/29
`4,684,963
`11/1987 P’
`........
`.. 347/49
`4,709
`5
`4709316 “/1987 P3361“.
`” 347!“
`__
`4'709247 11/1987 Hm ct at
`347,87
`4,734,713
`3,1933 Iwagami ct 31’
`__ 347,29
`4,755,836
`7/1933 Ta et al.
`.. 347/49
`4,853,717
`8/1939 Harmon et al
`.. 347/29
`4,952,947
`8/1990
`
`-
`
`IBM Technical Disclosme Bulletin, “Replaceable Ink Car-
`‘ridge for Ink Jet Print Heed," 341459-462 (1991)-
`Primary Examiner—John E. Barlow, Jr.
`[57]
`ABSTRACT
`
`An ink pen is provided with a protective capping apparatus
`to protect against damage caused by the ingress of dirt and
`debris, the accumulation or solidification of ink. the dis-
`chargc of Static elewicity or the mm The protective capping
`-
`apparatus has a protective cap movable between an open
`position and a closed position. In the closed position the
`protective cap shields a portion of an ink pen such as the
`Ink-Jets or the electrical Contacts-
`
`14 Claims, 5 Drawing Sheets
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`W.
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`.9.“O
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`0092
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`7991
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`Sheet 2 of 5
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`5,682,186
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`Sheet 3 of 5
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`’IIIIIIII-.ruuuuuuuuuu'I
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`Sheet 4 of 5
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`Oct. 28, 1997
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`Sheet 5 of 5
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`FIG. 11
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`5,682,186
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`1
`PROTECTIVE CAPPING APPARATUS FOR
`AN INK-JET PEN
`BACKGROUND INFORMATION
`
`The present invention relates to pens for ink-jet printers
`and, more particularly to a protective capping apparatus for
`such pens.
`Ink-jet printers have become widely accepted as areliable
`means of performing high quality printing. Such printers
`have one or more ink-jets which serve to eject, or jet, ink
`onto a printing medium to form desired characters or
`images. One type of ink-jet printer is a thermal ink-jet
`p-inter. In a typical thermal ink-jet printer, each thermal
`ink-jet has an orifice, a well for storing a small quantity of
`ink, and a thermal element such as a resistor. The thermal
`ink-jet is actuated by heating the thermal element to cause
`the small quantity of ink within the well to vaporize and be
`expelled through the orifice.
`Ink-jet printers often employ ink pens. Such pens com-
`monly have an ink reservoir for containing a supply of ink,
`a print head having an array of one or more ink-jets, and an
`electrical contact pad. The electrical contact pad has one or
`more elecuical contacts which. when the ink pen is posi-
`tioned within a printer, engage with corresponding contacts
`in the printer to allow electrical connection of the ink-jets to
`the control system of the printa. In this manna", the printer
`control system can selectively actuate the ink-jets to print
`desired images. Ink pens are generally replaceable so that
`when the supply of ink within the reservoir is depleted or the
`print head malfunctions, the ink pen can be removed from
`the printer, discarded, and a new pen inserted into the printer.
`As can be appreciated ink pens are delicate instruments
`which must be protected to ensure proper operation. For
`instance, the tiny orifices of the ink-jets can become plugged
`or damaged as a result of the accumulation of dust and dirt.
`This problem is exacerbated because of the abundant
`amount of dust and small paper fibers that exist in most
`printing environments. These materials may build up on the
`print head and clog the ink-jets or may enter an orifice and
`contaminate the ink within the orifice or the well.
`Vapor loss may also cause an ink pen to malfunction. Ink
`is a combination of many difierent components, some of
`which evaporate more readily than others. As a result,
`prolonged exposure of the ink to the ambient atmosphere
`may cause the easily evaporated components to evaporate
`while the other components remain. This selective evapo-
`ration can alter the composition of the ink to the point where
`the ink pen can no longer function properly. In extreme
`cases, the ink within the orifice may thicken or solidify,
`thereby plugging the orifice.
`An ink pen may also become inoperable if the electrical
`contact pad is scratched or if the contacts become obscured
`with
`If the contacts are damaged or obscured, the
`continuity of the electrical connection between the printer
`control system and the ink-jets may be broken. This may
`prevent the proper actuation of the aifected ink-jet and
`require replacement of the entire pen.
`In addition, ink pens are vulnerable to damage firom the
`discharge of static electricity. A static electrical charge may
`build up while the ink pen is in service within a printer. This
`accumulated static charge may discharge when the ink pen
`comes into contact with a conductive material. either within
`the printer, during ink pen removal from the printer, or while
`the ink pen is out of the printer. Such a discharge can
`seriously damage die sensitive electrical circuits associated
`with the print head and the contact pads, as well as the
`(rifices on the print head.
`
`5
`
`2
`Thus. to ensure the reliable and eflicient operation of an
`ink pen, it is desirable to protect the sensitive print head and
`electrical contact pad at all times. In some existing ink pens,
`the print head is covered with tape during the manufacture
`of the pen. The tape serves as a vapor barrier to limit vapor
`loss or evaporation of the ink and covers the print head to
`help prevent contamination of the print head and ink-jets
`during shipment and initial storage of the inkpen. However,
`the tape is removed and discarded prior to placing the ink
`pen within a printer. As a result, the print head and ink-jets
`may be left unprotected and without an adequate vapor
`barrier during use and during any subsequent storage of the
`ink pen.
`Some printers are provided with built-in carping stations.
`During printing operations, the printer typically moves the
`ink pen back and forth ova the painting medium to print the
`desired images. When the ink pen is not in service, the '
`printer moves the ink pen to the capping station where the
`print head and ink-jets are shielded. However, over time
`such permanent capping stations can become dirty or wear
`out. If this occurs. the capping stations no longer perform
`properly and docking an ink pen at such a capping station
`may even contribute to the contamination of the print head.
`Moreover, such built-in capping stations may become obso-
`lete as ink pen designs change.
`Special storage containers, or ink pen garages, are also
`available to protect ink pens. However, to place the ink pen
`within the ink pen garage, the inkpen must be removed from
`the printer. Consequently, the ink pen must then be removed
`from the garage and replaced within the printer for use. As
`a result, the use of such containers is inconvenient and in
`many circumstances impractical.
`SUMMARY OF THE INVENTION
`
`Accordingly, it is an object of the present invention to
`provide a protective capping apparatus for an ink pen that
`protects the print head, the electrical contacts, or both, from
`contamination and damage.
`Another object of the invention is to provide a protective
`capping apparatus for an inkpen that protects the print head.
`the electrical contacts. or both. against damage caused by the
`discharge of static electricity.
`A protective capping apparatus in accordance with one
`aspect of the present invention has a protective cap attached
`to an ink pen and movable between an open position and a
`closed position. In the closed position the protective cap
`shields a portion of the ink pen to rxotect it from damage by
`the ingress of dirt and debris, the accumulation or solidifi-
`cation of ink, the discharge of static electricity or the like.
`In one aspect of the invention, the protective cap can pivot
`between the closed position and the open position and is
`positioned such that in the closed position the cap protects
`the ink-jets of a print head.
`'
`In another aspect of the invention, the protective cap is
`slidable between the closed position and the open position
`and is positioned such that in the closed position the cap
`shields the print head, the electrical contacts, or both.
`In yet another aspect of the invention, the protective cap
`wipes the print head and/or the electrical contacts when the
`protective cap moves between the closed and open positions.
`Other objects and aspects of the invention will become
`apparent to those skilled in the art from the detailed descrip-
`tion of the invention which is presented by way of example
`and not as a limitation of the present invention.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a perspective view showing the bottom and sides
`of an ink pen having a protective capping mechanism in
`accordance with a preferred embodiment of the present
`invention.
`
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`3
`FIG. 2 is a partial perspective view of the protective
`capping apparatus of FIG. 1 in a closed position.
`' FIG. 3 is a partial perspective view showing the bottom of
`an ink pen having a protective capping apparatus in accor-
`dance with an alternative preferred embodiment of the
`present invention.
`FIG. 4 shows the protective capping mechanism of FIG.
`3 in an open position.
`FIG. 5 is a bottom plan view of ink pen having a
`protective capping apparatus in accordance with another
`preferred embodiment of the present invention and a set of
`cam ramps for actuating the protective capping apparatus.
`The ink pen with the capping apparatus in the open position
`is shown in phantom.
`.
`FIG. 6 is a side view taken along line 6-6 in FIG. 5.
`FIG. 7 is a side view of the cam ramps taken along line
`7—7 in FIG. 5.
`
`FIG. 8 is perspective View of an ink pen having a
`protective capping apparatus with a wiper in accordance
`with anotha prefm-red embodiment of the present invention.
`FIG. 9 is a partially cut-away perspective view showing
`the bottom and sides of an ink pen having a capping
`apparatus in the closed position in accordance with another
`peferred embodiment of the present invention.
`FIG. 10 shows the protective capping apparatus of FIG. 9
`in an open position.
`FIG. 11 is a partially exploded perspective view of a print
`head having a protective capping apparatus in accordance
`with anotha preferred embodiment of the present invention.
`FIG. 12 is a cross sectional View taken along line 12—12
`in FIG. 11.
`
`FIG. 13 is a partial side view of a print head having a
`capping mechanism in accordance with anotha preferred
`embodiment of the present invention.
`DESCRIPTION OF THE ILLUSTRATED
`EMBODINIENTS
`
`An ink pen capping device in accordance with a preferred
`embodiment of the present invention is designated in FIG. 1
`with reference numeral 10. The illustrated capping device
`includes a cap 12 pivotably mounted to the low: end of an
`ink pen 14. The cap can be pivoted from an open position to
`a closed position. In the closed position, the cap covers
`sensitive portions of the inkpen to shield them from damage
`and to limit the ingress of dust. paper fibers, and other
`contaminants.
`
`As seen in FIGS. 1 and 2, the capping device It) is situated
`on an ink pen 14. The illustrated ink pen 14 has a reservoir
`18 for holding a supply of ink. A print head 16 is in fluid
`communication with the resuvoir 18. The print head 16 is
`uovided with an array of ink-jets 20 each of which can be
`selectively actuated. by providing an electrical signal to the
`ink-jet, to eject ink and form desired characters and images.
`A flexible strip conductor 22 extends from the print head
`16 and terminates in a contact pad 24 which is fixed to one
`side of the reservoir 18. The contact pad 24 has an array of
`exposed electrical contacts 26. The strip conductor contains
`a number of electtiml leads extending from the electrical
`contacts 26 to circuitry associated with the ink-jets 20. When
`the ink pen 14 is positioned within a printer (not shown)
`these electrical contacts 26 engage corresponding contacts
`on the printer. In this manner, the control system of the
`printer can selectively actuate any given ink-jet 20 by
`providing an electrical signal to the appropriate contact or
`contacts.
`
`10
`
`4
`In embodiment illustrated in FIGS. 1 and 2, the print head
`16 is mounted on a support platform 28 which extends from
`the bottom of the ink pen 14. A pivot post 30 extends
`laterally from each side of the support platform 28. Each
`pivot post 30 is received in a corresponding aperture formed
`in the cap 12. In this manner, the cap 12 is pivotably fixed
`to the ink pen 14.
`The cap 12 can pivot about the post 30 between an open
`position, shown in FIG. 1. and a closed position, shown in
`FIG. 2. As illustrated,
`the ink pen 14 and cap 12 are
`configured such that, in the open position, the cap 12 fits
`compactly against the bottom of the ink pen 14 where it does
`not interfere with the operafion of the ink pen or printer. In
`the closed position, the cap 12 covers the print head 16 to
`shield it from potentially damaging contact with foreign
`objects and to limit the ingress of din, Paper fibers, and other
`damaging contaminants into the ink-jets 20. The cap 12 also
`protects the print head from damage from electrostatic
`discharge.
`In the illustrated embodiment. the effectiveness of the cap
`12 is enhanced by providing a gasket 34 on the cap 12. As
`best shown in FIG. 1, the gasket 34, which is preferably an
`elastomeric material, is positioned on the cap 12 such that
`when the cap 12 is in the closed position the gasket abuts the
`print head 16 to define a protective chamber 36 about the
`ink-jets 20 without requiring the cap 12 to be in contact with
`the sensitive and easily damaged ink-jets 20. The protective
`chamber 36 serves as a humidity or vapor barrier to help
`maintain a high humidity within the chamber 36 and prevent
`any ink within the ink-jets 20 from evaporating or solidify-
`ing. This configuration also reduces the possibility that any
`debris or contaminants which might build up around an
`ink-jet 20 while the cap 12 is in the open position will be
`forced into the ink-jet when the cap is closed
`In some embodiments, it may be desirable to provide a
`vent 38 for the chamber 36 to help maintain an equilibrium
`between the air pressure inside the chamber 36 and the
`ambient. In the embodiment of FIG. 1 and 2, the cap has a
`vent 38 with an internal opening 40 within the chamber 36.
`A diffusion channel 42 extends from the intanal opening 40
`through the cap 12 to an external opening 44. ‘The vent 38
`acts to prevent an air pressure spike within the protective
`chamber 36 from forcing air into an inkjet. At the same time,
`the vent preserves the humidity or vapor barrier.
`In the embodiment of FIGS. 1 and 2, the internal opening
`40 extends completely through the cap 12 and the bottom of
`the dilfusion channel 42 is defined by a trough formed on the
`outer surface of the cap 12. A cover 46 is placed over the
`t:rough to seal the top of the ditfusion channel 42. The
`external opening 44 extends through the cover 46 and opens
`into the ditfusion channel 42.
`While the illustrated vent 38 with the elongated dilfusion
`channel 42 advantageously serves to inhibit evaporation and
`solidification of ink within the ink-jets, it should be under-
`stood that alternative venting schemes may also be used. For
`example, in alternative embodiments, the vent may be a hole
`extending directly through the cap 12 and into the chamber
`36.
`
`In some embodiments, it may also be desirable to position
`an absorbent member (not shown) on the inner surface of the
`cap 12. The absorbent member can absorb ink spilled from
`the ink-jets during shipping and ink remaining on the print
`head after printing. Thereby, such accumulated ink is pre-
`vented from collecting contaminants or solidifying and
`blocking the ink-jets. Such an absorbent member could also
`help to maintain a humid environment around the ink-jets to
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`prevent ink within the nozzles from evaporating or solidi-
`fying. Such an absorbent member could be used either in
`combination with a gasket or without a gasket.
`In the embodiment illustrated in FIGS. 1 and 2, a torsion
`spring 4-8 is provided to urge the cap 12 into the closed
`position. One end of the torsion spring 48 engages the cap
`12 and the other end engages a recess 50 in the ink pen 14.
`The centrally located coil of the torsion spring 48 surrounds
`one of the pivot posts 30 to help maintain the spring 48 in
`the proper position. In this manner, the torsion spring 48
`serves to bias the cap toward the closed position and ensure
`that the cap is maintained firmly in its protective position
`when in the closed position.
`Of course. it should be appreciated that other types of
`springs or biasing devices may work equally as well as the
`torsion spring 48 illustrated in FIGS. 1 and 2. Moreover, in
`some embodiments, it may not be necessary or desirable to
`have such a biasing device.
`Indeed, some embodiments of this invention may include
`manual opening and closing of the protective cap by the
`operator of the printer. Other embodiments may include
`printer-based actuator mechanisms that move the protective
`cap between the open and closed positions with or without
`pen-based biasing devices.
`As seen in FIGS. 1 and 2, the illustrated embodiment
`includes a latch 52 to hold the cap 12 in the open positions.
`The latch 52 has an overhanging protuberance 54 extending
`therefrom. In FIG. 1, the latch 52 is positioned such that
`when the cap 12 is in the open position, the protuberance 54
`engages a tab 62 extending from the cap 12 to maintain the
`cap in the open position. The latch 52 flexes outwardly to
`allow the cap 12 to be moved into or out of the open
`position. A similar latch 56 can be provided to help maintain
`the cap 12 in the closed position. As shown in FIG. 2, latch
`56 engages the edge of the cap 12 to maintain the cap in the
`closed position. It is to be understood that other latch types
`can be used with equally good results. Moreova, the latches
`may not be required in embodiments where biasing devices
`hold the cap in position, or where printer-based actuator
`mechanisms hold the cap in position.
`There are several possible mechanisms for moving the
`cap 12 from the open position to the closed position. For
`example, as illustrated in FIGS. 3 and 4, a motor 58 could
`be used to actuate the cap 12. In the embodiment illustrated
`in FIGS. 3 and 4, the motor is provided with a forked
`actuator 60 which engages a tab 62 formed on the cap 12. In
`this manner, the motor can be driven in one direction to open
`the cap and in the other direction to close the cap.
`Although the motor may be mounted directly to the ink
`pen carriage, in the illustrated embodiment, the motor is
`mounted adjacent a home station of the ink pen within the
`printer. When the printer is not printing, the ink pen 14 is
`nonnally moved to the home station whue the forked
`actuator 60 engages the tab 62 to allow the motor 58 to move
`the cap 12 to the closed position. Upon activation of the
`printer, the motor 58 moves the cap 12 to the open position
`and the ink pen 14 is moved from the home station, thereby
`disengaging the tab 62 from the forked actuator 60.
`In the embodiment of FIGS. 3 and 4, the cap is maintained
`in the open position during [tinting operations by means of
`a latch 52. When at the home station, the cap can be held in
`the closed position by the motor. Alternatively, a latch or a
`spring could be provided to hold the cap in the closed
`position.
`FIGS. 5-7 illustrate an alternative mechanism for moving
`the cap 12 between the open position and the closed posi-
`
`60
`
`6
`tion. In this mechanism. two cam ramps 64 and 66 are
`situated within a printer (not shown) such that as the ink pen
`14 is moved along the cam ramps 64 and 66 they engage the
`tab 62 to move the cap 12 into either the closed position or
`the open position, depending on the direction of movement.
`Each cam ramp 64 and 66 is a band or wire having the
`general shape of a half of a revolution of a spiral. In the
`illustrated embodiment,
`the cam ramps 64 and 66 are
`positioned adjacent one another and next to the home station
`of the ink pen 14. In this manner, as the inkpen 14 is moved
`into the home station (illustrated in phantom in FIG. 5) the
`tab 62 engages an edge 65 of cam ramp 64. Further lateral
`movement of the ink pen 14 causes the tab 62 to follow the
`edge 65 of the cam ramp 64 to thereby move the cap 12 into
`the closed position.
`Conversely, as the ink pen 14 is moved from the home
`position, the tab 62 engages an edge 67 of cam ramp 66.
`Further movement of the pen causes the tab 62 to follow the
`edge 67 of the cam ramp 66, thereby moving the cap 12 into
`the open position. The cap can be held in the open or closed
`position by latches, springs. or other si.1'nilar devices.
`Although a motor—driven actuator, biasing members. and
`tab engaging cam ramps have been illustrated as providing
`a mechanism for moving the cap between the open and
`closed positions, it should be appreciated that a variety of
`dilferent, yet equivalent, structures could be used to perform
`this function.
`
`FIG. 8 shows another preferred embodiment of a protec-
`tive capping apparatus in accordance with the present inven-
`tion. This embodiment has a sliding cap 68 which slides
`between an open position in which the ink-jets 20 are
`exposed and a closed position in which the ink-jets 20 are
`covered. The sliding cap 68 is ixovided with legs 70 which
`are slidably received within guide tracks 72 formed on each
`side of the support platform 28.
`An elastomeric gasket (not shown) can be positioned on
`the sliding cap 68 to form a protective seal around the
`ink-jets 20 when the sliding cap 68 is in the closed position.
`This seal acts as a vapor barria to help prevent the solidi-
`fication of the ink resulting from evaptxation. A wiper 74
`can also be provided. The wiper 74 is positioned so that as
`the sliding cap 68 moves between the open position and the
`closed position, it wipes across the surface of the ink-jets 20
`to remove any dirt, debris or accumulated ink.
`FIGS. 9 and 10 show an alternative embodiment in which
`a sliding cap 680 is positioned to slide between an open
`position in which the contact pad 24 is exposed and a closed
`position in which the contact pad 24 is covered. Sliding cap
`68a has legs 70a that engage guide tracks 72:: formed in the
`side of the ink reservoir 18. The sliding cap 68a can be
`provided with extensions 76 which, when the sliding cap is
`in the closed position, extend beyond the end of the ink pen
`to shield the print head 16 from direct contact with foreign
`objects.
`It may be desirable to electrically insulate the sliding cap
`68a from the contact pad 24 and to form an electrical path
`from the sliding cap 68:: to the ink pen 14. This will help
`shield the contact pad 24 from damage caused by the
`discharge of static electricity. In a similar manner,
`the
`extensions 76 of the slider cap 68a help prevent the print
`head 16 from coming into direct contact with foreign objects
`to protect it against damage from static electrical discharge
`from the print head 16.
`Alternatively, the slider caps 68, 68a may be made of
`non-conductive material and still help electrically insulate
`the print head and/or contact pad 24 from static electrical
`
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`7
`discharge. It is also to be understood that the electrical
`insulation feature may be applied to all embodiments of the
`protective capping apparatus, including the pivotable print
`head cap embodiments of FIGS. 1-6. Non-conductive caps,
`or conductive caps having conductive pathways to the ink
`pen to electrically insulate the print head, work equally well
`with the embodiments.
`FIGS. 11-13 show a protective capping mechanism for a
`page wide print head 78. The illustrated page wide print head
`78 has a curved front surface 80 with a number of ink-jets
`formed therein. A protective cap 82 is pivotable between a
`closed position in which it shields the fiont surface 80 and
`an open position in which the front surface 80 is exposed.
`The protective cap 82 is provided with a leg 84 at each end.
`An aperture 86 in each leg 84 is received on a pivot post 88
`extending fiom the page wide print head 78. In this manner,
`the protective cap can pivot between the closed position and
`the open position.
`In the embodiment illustrated in FIG. 12, a gasket 90 is
`positioned on the protective cap 82 to form a protective
`chamber 91 around ink-jets on the front surface 80. Awiper
`92 is positioned so as to wipe across the front surface to
`remove any accurmrlated dirt. debris or excess ink. The
`position of the pivot posts 88 and the length of the legs 84
`can be varied to achieve a desired movement of the gasket
`and wiper across the front surface. For example, if the pivot
`posts 88 are positioned at the center of curvature of the front
`surface. as shown in FIGS. 11 and 12. the wipa and the
`gasket will wipe across the entire front surface.
`However. it may be desired that the pivot posts are offset
`slightly fi'om the center of curvature of the front surface 80
`so that the gasket tends to lift from the front surface as the
`protective cap is pivoted. In the embodiment shown in FIG.
`13. the pivot posts (not shown) of the cap 8217 are offset (in
`the direction of the open position) from the center of
`curvature of the front surface 80.
`To provide for the wiping of the front surface 80, a
`spring-biased wiper arm 94 is rockably positioned upon the
`protective cap 821:. The wiper arm 94 has a ledge 96 which
`extends over the longitudinal edge of the cap opposite the
`direction of the open position. A wiper 92a is attached to
`protrude from the ledge 96 and extend longitudinally along
`the front surface 80. A biasing member 95 urges the wiper
`92 into contact with the front surface 80. In is [referred
`embodiment, the biasing member 95 is a compression spring
`that interconnects the cap 82b and the wiper arm 94 opposite
`the ledge 96. The spring 95 is compressed when the cap is
`in the closed position. As the cap opens. the gasket 90 lifts
`fiom the front surface 80, while the spring 95 expands to
`urge the wiper 92 into sweeping contact with the front
`surface 80.
`
`This embodiment has advantages when. for example, the
`gasket material
`is not suitable for wiping, or when an
`absorbent member not suitable for wiping is installed on the
`cap. It should be understood that the wiper arm 94 may be
`biased in a variety of ways. For example, a torsion spring
`similar to the torsion spring 48 in FIGS. 1 and 2 may be
`used. Alternatively. a tension spring positioned adjacent the
`ledge 96 may be used to urge the wiper 92 into contact with
`the front surface 80.
`
`It should be appreciated that protective cap mechanisms
`in accordance with the present invention may be actuated by
`a variety of suitable mechanisms. The motor and actuating
`arm illustrated in FIGS. 3 and 4 and the cam ramps illus-
`trated in FIGS. 5-7 are only two of many such mechanisms.
`Clearly variations of these mechanisms as well as other
`mechanisms will be apparent to those skilled in the an.
`
`8
`Moreover, the illustrated print heads all have thermal
`ink—jets. However, it should be appreciated that a capping
`device in accordance with the present invention may be used
`beneficially with other types of ink-jets or with other types
`of print heads.
`This detailed description is set forth only for purposes of
`illustrating examples of the present invention and should not
`be considered to limit the invention in any way. Clearly,
`numerous additions, substitutions, and modifications can be
`made to these examples without departing from the scope of
`the invention which is defined by the appended claims and
`their equivalents.
`We claim:
`1. An ink pen assembly comprising:
`an ink pen having a print head and at least one exposed
`electrical contact on the exterior of the pen and a cap
`attached to and carried by the ink pen. the cap having
`an open position and a closed position and being
`slidable on the ink pen along a straight path between the
`open position and closed position, in which the cap
`shields the electrical contact.
`2. The ink pen assembly of claim 1 wherein the ink pen
`has an exterior surface and the print head is on the exterior
`surface. the exterior surface having guide uacks formed
`therein adjacent the print head, and the cap including legs for
`engaging the guide tracks on the ink pen to guide the cap
`between the open and closed positions.
`3. An ink pen assembly comprising:
`an ink pen having a print head;
`a cap mounted to the ink pen, the cap having an open
`position and a closed position, and movable between
`the open position and the closed position in which the
`cap covas a least a portion of the print head; and
`a resilient latch mounted to the ink pen and having a
`protuberance which engages the cap when the cap is in
`one of the open position and the closed position to
`maintain the cap in the one position, the latch resiliently
`flexible to pamit the cap to move past the protuberance
`out of the one position when a selected force is applied
`to the cap; and
`wherein at least a portion of the cap is made from a
`conductive material to electrically couple the cap to the
`ink pen in the open position and the closed position.
`4. A system for protecting an ink pen having a print head,
`comprising:
`an ink pen having a print head;
`a cap attached to the ink pen and movable between an
`open position and a closed position in which the cap
`shields a portion of the print head;
`a wiper arm mounted to the cap and having a ledge
`protruding beyond the cap;
`a wiper mounted to the ledge to wipe over at least a
`portion of the print head when the cap moves between
`the open and closed positions; and
`a biasing member situated between the wiper arm and the
`cap, the biasing member engaging the wiper arm to
`urge the wiper into sweeping contact with the print
`head as the cap moves from the closed to the open
`position.
`5. A system for protecting a traveling ink pen comprising:
`a cap pivotally mounted to and travelling with the ink pen
`and having an open position and a closed position, the
`cap pivotable between the closed position wherein the
`cap shields a portion of the ink pen and the open
`position; and
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`a cam ramp located near the cap in a fixed position to
`engage the cap as me cap travels with the ink pen to
`move the cap between the open and closed positions.
`6. A system for protecting a traveling ink pen comprising:
`a cap pivotally mounted to and traveling wit:h the ink pen
`and having an open position and a closed position, the
`cab pivotable between the closed position wherein the
`cap shields a portion of the ink pen and the open
`position; and
`a cam ramp located near the cap in a fixed position to
`engage the cap as the cap travels with the ink pen to
`move the cap between the open and closed positions
`and wherein the cam ramp has a part that engages the
`cap, and the part defines a ca.n1 path having a shape of
`a portion of a revolution of a helix.
`7. An ink pen assembly having an electrical contact pad
`for Contact with electrical contacts on a printer, the ink pen
`assembly comprising:
`an ink pen having an exterior surfac