Method and apparatus for refilling ink jet unit printer cartridges

BACKGROUND OF THE INVENTION

The invention comprises method and apparatus in the form of a kit which is principally applicable but not limited to the refilling of printer ink cartridges of the type defined in United States Patents No. 5,040,001 dated Aug. 13, 1991 and No. 5,359,353 dated Oct. 25, 1994. A fresh printer ink cartridge of the latter kind consists of a rigid external housing containing an inner sealed unit holding approximately 40 ml of ink with a nozzle array intended to eject ink drops during printing. To activate, the user removes a tape seal from the nozzle plate. There is no intentional air inside the unit and the ink inside the printer ink cartridge can only exit that cartridge from the nozzles, as is the case during printing in the printer or plotter. Although a fill hole is present in the cartridge, this hole is sealed with a ball by the manufacturer and no air can enter the cartridge. Characteristically there are more than 60 and as many as 200 nozzles, all of which however have such small diameters, typically less than 75µ, such that relatively strong negative pressures inside the cartridge are needed to pull air into the cartridge through any of the nozzles. This does not occur during normal operation of the printer ink cartridge.

As ink is ejected from the nozzles during printing, two internal opposed springs hold side plates apart in the cartridge. These provide for a moderate negative pressure inside the unit which prevents the ink from coming out of the nozzles during the non-printing state of the unit. The springs collapse slowly to compensate for the decrease in ink volume. Color paper tabs connected to the outside of the inner flexible unit are made to move relative to one another by the motion of the side plates to indicate amount of ink remaining. The plates continue to approach each other as ink is used up during normal operation of the cartridge. There being no air in the printer ink cartridge, the cartridge is relatively insensitive to temperature and pressure changes, since the ink does not appreciably expand or contract. Even if some small quantity of air does get trapped in the cartridge, the springs compensate for any volumetric changes and keep the pressure in the ink at the nozzle level at a negative value, thereby preventing ink from drooling from the nozzle plate.

When the ink jet printer ink cartridge nears the end of its ink content, the opposing plates, kept separate by the spring arrangement, begin to touch and greater and greater negative pressures are created in the cartridge since no further reduction of volume is possible. The cartridge begins to eject smaller drops and eventually to fail to eject drops from some of the nozzles, since refill of the nozzle chambers begins to take more and more time. With further depletion of ink, nozzles fail at such a rate that print quality becomes totally unacceptable and the user is forced to replace the cartridge even if he had up till then, ignored the color tab low ink indicator. Typical pressures during the operating life of the cartridge range from -15 to -35 cm of water which is adequate to prevent ink from exiting the nozzles and not too negative to interfere with drop formation at the nozzle orifice.

This invention is directed to the most efficient refilling of such ink jet cartridges.

THE PRIOR ART

The known prior art includes the following:    US-A-4,967,207, US-A-5,199,470, US-A-5,280,300, US-A-5,329,294, US-A-5,359,353 and US-A-5,400,573.

The problem with maintaining negative pressure in the refilling of printer ink cartridges, having collapsible reservoirs, is recognized in US-A-4,967,207 and No. 5,280,300, set forth above. Within this invention, a nozzle stopper stem over a fill hole of the ink jet cartridge, dislodges its existing sealing ball and separates it during the extraction of ink to effectively reseal the ink jet unit after the refill process. Interferences are chosen such that the stopper stays on the refilling stem until the operator removes the principal refill clamp from the ink jet unit. The filling station cartridge itself is provided with a moveable sliding cartridge sealing plug that in the two preferred locations initiates and terminates the refill process. The sealing plug serves to assist in depressurizing the refilled printer ink cartridge when it is moved to its sealing position. Unlike prior art, activation of the ink reservoir for the refill kit is achieved by rotating one filler unit part relative to another. A sliding, rotating relative part motion is used to depressurize the ink jet unit, to automatically obtain the required negative pressure for ink jet unit stability, upon removal of the filling station apparatus from the ink jet unit, per se. The stopper automatically seals the fill hole to maintain the negative pressure.

SUMMARY OF THE INVENTION

There are two types of cartridge herein. With respect to the ink jet unit, there is its printer ink cartridge which contains a collapsible inner sealed unit. With respect to the invention there is the filing station cartridge, per se.

As applied to Type 640 HP Printer Ink Cartridges and the like, ink refilling is accomplished through the use of a slideable cartridge sealing plug which initiates and terminates the refill process. Depressurizing the printer ink cartridge is achieved by rotation of cartridge relative to the adapter whereby the ink jet unit automatically obtains negative pressure. At an ink jet unit filling station, one <i>first</i> inserts a clamp/ink cartridge assembly, displacing the sealing ball of the printer ink cartridge. <i>Second</i>, the ink cartridge is rotated relative to its clamp to dislodge the stopper of the ink cartridge; <i>third</i>, the filler cartridge assembly plug is removed, sucking ink into the ink jet unit; <i>fourth</i>, the filler cartridge assembly plug is replaced; <i>fifth</i>, the ink jet unit is depressurized; and <i>sixth</i>, the clamp/ink cartridge assembly, the filling station, is removed from the ink jet unit sealing it and preparing it for another later refill.

DESCRIPTION OF THE DRAWINGS

<b>FIGURE 1A</b> is a schematic view in side elevation of an ink refilling station attached to a conventional ink jet unit with reservoir, and <b>FIGURE 1B</b> is a frontal elevation view thereof.

<b>FIGURE 2A</b> is a schematic view in front elevation of the attached ink refilling apparatus assembly of <b>FIGS 1</b> and <b>1A</b>, the same being activated for starting of the filling method, second phase. <b>FIGURE 2B</b> is an enlarged vertical section of an interior portion of <b>FIG. 2A</b>.

<b>FIGURE 3</b> illustrates, in schematic detail the third phase relationship between the filling station assembly of the invention and a conventional ink jet unit with reservoir wherein ink is sucked into the ink jet unit and its reservoir by virtue of lifting displacement of the filling station plug.

<b>FIGURE 4</b> illustrates in schematic detail the fourth phase relationship between ink refill cartridge assembly and conventional ink jet unit with reservoir, wherein the filler plug is downwardly replaced, relative to the ink jet cartridge unit.

<b>FIGURE 5A</b> illustrates in schematic detail the fifth phase in the disposition of elements of filling station relative to each other, for back pressurization of the ink jet unit reservoir. <b>FIGURE 5B</b> is an enlarged vertical section of an interior portion of <b>FIG. 5A</b>.

<b>FIGURE 6A</b> illustrates, in schematic detail, the sixth phase in the removal of ink refill cartridge and clamp assembly from the ink jet unit with reservoir. <b>FIGURE 6B</b> is an enlarged vertical section of an interior portion of the ink jet unit of <b>FIG. 6A</b>.

<b>FIGURE 7A</b> is a vertical section view of the filling station assembly, less the ink jet unit of <b>FIGS. 1-1A</b> and <b>2-6</b> inclusive of the drawings, taken along the lines 7-7 of <b>FIG. 1A</b>. <b>FIGURE 7B</b> is an enlarged vertical section of a portion of <b>FIG. 7A</b>.

DESCRIPTION OF PREFERRED EMBODIMENTS

APPARATUS AS APPLIED TO INK JET UNIT

Referring to <b>FIGS. 1A-B, 2A-B</b>, <b>3</b>, <b>4</b>, <b>5A-B</b>, <b>6A-B</b>, <b>7A-B</b> of drawings, filling station <b>100</b> for ink jet unit <b>200</b> includes, inter alia, clamp <b>110</b> and the filler cartridge <b>120</b> with its stopper <b>121</b> and cartridge assembly plug <b>122</b>. See <b>FIGS. 2A</b> and <b>2B</b>. The damp <b>110</b> defines guidance tabs <b>112</b>, between which is retained nozzle stopper stem <b>113</b>, the latter stem defining transverse hole <b>114</b>. See <b>FIG. 7A</b> and <b>7B</b>. A stopper <b>117</b> is displaceably set upon the stopper stem extension <b>116</b>. Stem <b>113</b> and its extension <b>116</b>, being terminated by this stopper <b>117</b>, have an essential function during removal of the clamp <b>110</b> from ink jet reservoir cartridge <b>200</b>. See <b>FIGS. 6A</b> and <b>6B</b>. Associated with ink jet reservoir cartridge <b>200</b> is fill hole <b>201</b> and sealing ball <b>202</b>. Conventional decompression springs of the ink jet unit are not shown, nor is the conventional collapsible reservoir of the ink jet unit. As indicated, Pat. No. 5,280,300 clearly illustrates such conventional structure. Retention of stopper <b>117</b> in ink jet fill hole <b>201</b> depends upon the depth of the hole and its containment of the stopper's vertical extension. See <b>FIGS. 6</b> and <b>6A</b>.

As illustrated in <b>FIGS. 1A</b> and <b>1B</b>, biased retainers <b>118'</b> on an upper ring <b>118</b> of clamp <b>110</b> are adapted to interlock with a corresponding rim of the filler cartridge <b>120</b>. The retainers <b>118'</b> comprise vertical protrusions of wing extensions <b>118</b>. See <b>FIG. 7A</b>. Filler cartridge assembly plug <b>122</b> is to be temporarily dislodged See <b>FIG. 3</b>. The plug <b>122</b> having been pulled upwardly, its ink passage slot <b>123</b> is exposed to the atmosphere, resulting in drainage of ink from the filling station <b>100</b> into the overall ink jet reservoir assembly <b>200</b>. As will appear in <b>FIG. 5B</b>, there are coactively disposed two ramps. Ramp <b>115</b> is the mating ramp of clamp <b>110</b> and the related element is ramp <b>124</b> of the filler cartridge <b>120</b>.

METHOD OF REFILLING INK JET UNIT RESERVOIR

Having defined the invention with respect to the elements thereof, there follows a sequence in the filling operation. The clamp <b>110</b> and its slideably retained filler cartridge <b>120</b> are initially held in a deactivated relation by a suitable ink jet unit tray holder <b>300</b>. See <b>FIGS. 1A</b> and <b>1B</b>.

<i>First</i>, to commence preparation of the reservoir of the ink jet unit for refill, mount the filling station <b>100</b> on the airtight ink jet cartridge <b>200</b> by grasping the entire filling station unit <b>101-120</b> and firmly pressing it down onto the cartridge <b>200</b>. See <b>FIG. 1B</b>. Tabs <b>112</b> of the clamp <b>110</b> provide guidance onto the ink jet unit, accurately guiding the clamp <b>110</b>, per se, so that its nozzle stopper stem <b>113</b> is in correct position to enter the ink jet unit <b>200</b> via fill hole <b>201</b> and to simultaneously displace sealing ball <b>202</b> located therein. See <b>FIGS. 1A</b> and <b>7A</b>. This action is achieved in a single firm stroke. See <b>FIG. 1B</b>.

<i>Second</i>, to start the refill process, rotate the filler cartridge <b>120</b> one-third of a turn 120° relative to the clamp <b>110</b>, from an initial indent to a successive indent. Reverse rotation is prohibited by nonsymmetric shape of the indent of the conventional ink jet cartridge and of a mating protrusion of the clamp. As illustrated in <b>FIG. 2A-2B</b>, this initial rotational action dislodges internal stopper <b>121</b> of filler cartridge <b>120</b>, since it is pushed up by an appropriately located ramp <b>111</b>, located inside the bottom of the clamp <b>110</b>. See <b>FIG. 2B</b>. The negative pressure of the reservoir of ink jet <b>200</b>, with its conventional, collapsed internal springs, now pulls on the ink contained inside the filler cartridge <b>120</b> which, however at this point, cannot enter the reservoir of the ink jet <b>200</b> because the ink filler cartridge unit 120 remains airtight.

<i>Third</i>, to enable ink to be sucked into the reservoir of the ink jet unit <b>200</b>, pull the filler cartridge plug <b>122</b> up and away from filler cartridge <b>120</b>, to its maximum extended position, as illustrated in <b>FIG. 3</b>; thus air is allowed to enter the ink cartridge <b>200</b> through slot <b>123</b> on the stem of the plug <b>122</b>. Air entering the filler cartridge <b>120</b>, in turn, allows ink to be sucked through the hole <b>114</b> of the stopper stem <b>113</b>, into the collapsed ink jet cartridge <b>200</b> and filling it.

As the reservoir of the ink jet cartridge <b>200</b> fills, its internal springs gradually expand the internal volume of the conventional flexible reservoir container within cartridge <b>200</b>. Enough ink (± 43ml) is provided within cartridge <b>120</b> to fill the reservoir of the ink jet cartridge <b>200</b> to capacity. The positioning of critical elements, which permits sucking of ink from filler cartridge <b>120</b> to ink jet unit <b>200</b>, is depicted in <b>FIG. 3</b>.

<i>Fourth</i>, alter a predetermined time, or until ink exits the existing nozzle (not shown) of the ink jet unit <b>200</b>, the ink filler cartridge plug <b>122</b> is now pushed down, back to its sealing position, as illustrated i<b>n FIG. 4</b>, slowing the flow of any additional ink. Air which is now captive in the filler cartridge <b>120</b>, will decrease in pressure as more ink is removed, balancing the negative pressure of conventional internal container springs within the reservoir of the ink jet unit. Excess ink is carefully wiped from the nozzle face of the ink jet unit. This stops the filling process. See <b>FIG. 4</b>.

<i>Fifth</i>, to establish back pressure in the reservoir of the ink jet cartridge <b>200</b>, one again rotates ink filler cartridge <b>120</b> to 170° clockwise relative to the clamp <b>110</b>, to a successive click stop (not shown), which pushes the filler cartridge <b>120</b> out of the clamp <b>110</b> by an amount afforded by the height of the ramp <b>124</b> of the filler cartridge <b>120</b>. See the engaging of refill cartridge ramp <b>124</b> by the mating ramp <b>115</b> of the clamp <b>110</b>. This engagement results in an increase in internal volume of the cartridge 120. Since the volume of the captive ink and air is increased by this predetermined amount, the pressure in the reservoir of the ink cartridge <b>200</b> will collapse the conventional internal springs thereof a certain amount, thereby establishing the proper back pressure in the ink jet cartridge <b>200</b>, to prevent leakage. See <b>FIGS. 5A-B</b>.

<i>Sixth</i>, to firmly seal the ink jet cartridge <b>200</b>, in one firm stroke, pull up the ink refill cartridge and clamp assembly <b>100</b> by wing extensions <b>118</b> protruding from the clamp <b>110</b>, thus firmly removing the cartridge/clamp assembly <b>100</b>. See <b>FIG. 6A</b>. This motion preserves the negative pressure of the ink jet reservoir <b>200</b> and the slightly collapsed state of its springs therein, since the stem <b>113</b> and its extension <b>116</b> interfere slightly with the hole <b>201</b> in the ink jet unit. As the stopper stem <b>113</b> is thus extracted from the fill hole <b>201</b>, of the ink jet reservoir <b>200</b>, the interference fit between stem extension <b>116</b> and stopper <b>117</b> which was adequate to hold the stopper <b>117</b> on the stem <b>113</b> during transit and insertion, is inadequate to pull the stopper <b>117</b> through the hole and fails. As illustrated in <b>FIG. 6B</b>, this leaves stopper <b>117</b> firmly lodged in the ink jet unit fill hole <b>201</b>, sealing it and allowing the clamp and cartridge assembly <b>100</b> to be removed from the ink jet unit, thereafter to be discarded. The ink filler stopper <b>117</b> firmly in place in the refilled ink jet cartridge <b>200</b>, is designed to stay in place until the ink jet reservoir again runs out of ink and requires refilling. See both <b>FIGS. 6A</b> and <b>6B</b>.