Patent Publication Number: US-6655794-B2

Title: Methods and apparatus for curing a thermal sealing material using a heater trace

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to thermally cured sealing and/or adhesive materials, and more particularly to improved methods and apparatus for curing such materials with the aid of an electrically heated conductive element or heater trace. 
     BACKGROUND OF THE INVENTION 
     In the manufacture of various devices and components there is often a need to adhere one object to another object and/or seal a surface of one object to a surface of another object. Various adhesives, glues and other sealants are available that may be used for this purpose. One exemplary group of such “sealing materials” includes materials that are cured or otherwise activated, etc., using thermal energy (i.e., heat). 
     During the manufacture of certain ink jet print cartridges, for example, a flexible strip that includes various electrical contacts and electrical traces is adhered to a pen body using a cover layer adhesive. While the cover layer adhesive adequately holds the flexible strip and pen body together, there is an additional need to form a seal around all or part of the flexible strip to prevent certain liquids (such as corrosive ink) from coming in contact with the electrical traces/contacts. This seal, for example, can be formed using a thermally cured sealing material. Here, it should be understood that the sealing material can be a sealant, adhesive, or other type of material that can adequately provide a seal around all or part of the flexible strip. 
     In this print cartridge example, the sealing material is configured to prevent liquids such as inks, solvents, etc., associated with the operation and/or maintenance of the printing device and print cartridge, from seeping through and entering the cover layer adhesive region and electrically shorting or otherwise deleteriously affecting (e.g., corroding) the electrical traces/contacts provided on the flexible strip. As such, the sealing material needs to be selected such that it is substantially impermeable to such liquids and is able to withstand the operating parameters of the printing device/environment. The sealing material should also be selected such that it does not interfere with the operation of the print cartridge during printing operations. For example, in certain implementations, the sealing material may need to exhibit a significantly low physical profile to allow for the print cartridge to be operatively placed in close proximity to a print medium within the printing device. The selection of the sealing material may also be based on the needs of the manufacturing process. For example, to provide an efficient manufacturing process it may be beneficial to select a sealing material that can be quickly applied, cured and/or dried. 
     Based on these needs and/or others, thermally cured sealing materials appear to provide a satisfactory solution. Unfortunately, when conventional heating techniques such as, e.g., forced heated air, are employed to thermally cure the sealing material the resulting seal between the flexible strip and pen body may have small openings that allow inks and other liquids to penetrate though the seal. In certain instances, for example, it has been found that air that is trapped between the flexible strip and pen body during the application of the sealing material can expand during the subsequent thermal curing process and form bubbles or holes that breach the resulting seal. 
     Consequently, there is a need for improved methods and apparatus for thermally curing sealing materials. 
     SUMMARY OF THE INVENTION 
     Methods and apparatus are provided for forming a seal between two or more components using a thermally cured sealing material. One exemplary method includes selectively applying an electrical signal to a heating trace on a first component, applying a sealing material between at least a portion of the first component and at least a portion of a second component, and at least partially thermally curing the sealing material using thermal energy generated by the application of the electrical signal to the heating trace. 
     In certain implementations, the thermally cured sealing material is in physical contact with at least a portion of the electrical heater trace. The electrical heater trace may be positioned near an edge of the second component and configured to be substantially uniformly heated when the electrical signal is applied to it, or to be non-uniformly heated when the electrical signal is applied to it. In certain implementations, the first component may further include a channel corresponding to at least one edge of the second component and configured to receive the sealing material. In accordance with certain exemplary implementations of the present invention, the apparatus is a print cartridge, in which the first component includes a pen body and the second component includes a flexible strip. 
     In accordance with still other exemplary implementations of the present invention, a method is also provided for providing a seal between at least two components using a thermally cured sealing material. Here, for example, the method includes selectively applying an electrical signal to a heating element on a first component, applying a sealing material between at least a portion of the first component and at least a portion of a second component, and at least partially thermally curing the sealing material using thermal energy generated by the application of the electrical signal to the heating element. Here, the heating element may include a heater trace that is produces a substantially uniform amount of thermal energy along the heater trace or a non-uniform amount of thermal energy along the heater trace. The selective application of the electrical signal to the heating element may be done prior to applying the sealing material, while applying the sealing material, and/or after applying the sealing material. The sealing material may, for example, include a sealant, an adhesive, glue, or other like substance. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     A more complete understanding of the various methods and apparatus of the present invention may be had by reference to the following detailed description when taken in conjunction with the accompanying drawings wherein: 
     FIG. 1 is an illustrative diagram depicting a printing device having at least one removable/replaceable printing cartridge therein, in accordance with certain exemplary implementations of the present invention. 
     FIG. 2 is an illustrative diagram depicting a print cartridge, for example, as in FIG. 1, having a pen body and a flexible strip, in accordance with certain exemplary implementations of the present invention. 
     FIG. 3 is a further illustrative diagram depicting a print cartridge, for example, as in FIG. 2, wherein the flexible strip includes a heater trace, in accordance with certain exemplary implementations of the present invention. 
     FIG. 4 is an illustrative diagram depicting the application and curing of sealing material between the pen body and a flexible strip, for example, as in FIG. 3, in accordance with certain exemplary implementations of the present invention. 
     FIG. 5 is an illustrative diagram depicting the application and curing of sealing material between a pen body having a channel and a flexible strip, in accordance with certain further exemplary implementations of the present invention. 
     FIG. 6 is a flow diagram of a process for providing a seal between a pen body and a flexible strip, in accordance with certain exemplary implementations of the present invention. 
     FIG. 7 illustrates an exemplary layout view of a flexible strip, in accordance with certain implementations of the present invention. 
     FIG. 8 illustrates two views of a print cartridge having a flexible strip fixedly attached to a pen body and having a portion of the flexible strip that is sealed to the pen body, in accordance with certain exemplary implementations of the present invention. 
     FIG. 9 is a block diagram illustratively depicting two component parts that include a thermally cured sealing material interface there between and at least one heater trace or like heating element, in accordance with certain further exemplary implementations of the present invention. 
    
    
     DETAILED DESCRIPTION 
     While the following description focuses on improvements associated with the manufacture of print cartridges that are used with printing devices, it should be understood that the various methods and apparatus provided herein are clearly adaptable to other devices, components, etc. Indeed, as will be described with respect to FIG. 9, the methods and arrangements provided herein can be used to provide a seal between two or more surfaces of two or more objects/components using locally thermally cured “sealing materials”. 
     With this in mind, reference is now made to FIG. 1, which is an illustrative diagram depicting a printing device  100  having at least one removable/replaceable printing cartridge  102  therein, in accordance with certain exemplary implementations of the present invention. By way of example, printing device  100  may be an ink jet printer, a copier, a facsimile machine, or the like. As with conventional print cartridges, print cartridge  102  would typically include a reservoir of one or more inks, ink jet nozzle(s) and the supportive electrical elements needed to selectively cause one or more ink drops to be ejected from print cartridge  102  onto a print media (not shown). 
     FIG. 2 is an illustrative diagram further depicting two portions or components of print cartridge  102 , for example, as in FIG.  1 . Here, print cartridge  102  includes a pen body  202  and a flexible strip  204 , in accordance with certain exemplary implementations of the present invention. As illustrated by the dashed lines, flexible strip  204  is configured to flexibly conform to corresponding surfaces of pen body  202  when fixedly applied or attached thereto. Flexible strip  204 , in this example, includes various electrical traces and contacts that are arranged to support the printing operation. For example, electrically conducting contacts and traces can be provided that allow the printing device to selectively control the formation and outputting of ink drops or droplets by print cartridge  102 . Pen body  202 , in this example, would include at least one reservoir (e.g., a regulated bag) of liquid ink (not shown). 
     As described above in the Background section, there is a need to insure that certain inks, solvents, etc., do not come in contact with certain electrical contacts and/or traces provided by flexible strip  204 . One way to accomplish this is to form a seal between flexible strip  204  and pen body  202 . With regard to the exemplary implementation of print cartridge  204 , this seal is preferably formed near the edge of flexible strip  204 , and may extend around all or part of flexible strip  204 . 
     In this example, the seal is formed using a thermally cured “sealing material”. As mentioned above, it has been discovered that conventional heating techniques tend to cause small breaches in the seal due to expanding gases. These small openings may allow unwanted liquids to pass through the seal and come in contact with the electrical traces, etc, provided by flexible strip  204 . To reduce the potential for such openings in the seal, at least one heating trace may be added to flexible strip  204  and operatively/selectively configured to locally heat up certain areas of flexible strip  204  and nearby gases (e.g., air). The heating trace of the exemplary embodiment is formed simultaneously with and in the same manner and of the same materials as the various other electrical traces on flexible strip  204 , using processes known in the art. 
     Thus, for example, in accordance with certain implementations of the present invention, by selectively passing an electrical current through a heater trace on flexible strip  204  prior to and/or at about the same time as the sealing material is applied to flexible strip  204  and pen body  202 , the resulting thermal energy will expand the nearby gases in such a manner as to significantly reduce or eliminate the formation of unwanted vent holes, etc., in the resulting seal. Furthermore, the heater trace can be used to thermally cure the sealing material in such a manner that other portions of flexible strip  204  and/or pen body  202  are not significantly heated up. For example, unlike conventional forced air heating techniques, the more localized heat provided by the heater trace will reduce the possibility of heating up an internal ink-holding bag within pen body  202 . The trace may also be selectively energized to heat the sealing material to one temperature during the initial part of the curing process, during which time bubbles are prone to develop; and then, after the sealing material has cured sufficiently that it is relatively firm and bubble formation is inhibited, to a higher temperature to complete the curing process. 
     With these improvements in mind, attention is drawn to FIG. 3, which further illustratively depicts flexible strip  204  as having a heater trace  312  thereon, in accordance with certain exemplary implementations of the present invention. Here, flexible strip  204  includes an exposed side  205   a  and a trace side  205   b . A cover layer (adhesive)  330  is provided on trace side  205   b  along with heater trace  312 . In this exemplary implementation, heater trace  312  extends around trace side  205   b  and is not itself covered by cover layer  330 . In other implementations, heater trace  312  may extend around only a portion of trace side  204 , and/or may be at least partially in contact with cover layer  330 . In still other implementations, heater trace  312  may be provided on exposed side  205   a , and/or be configured internally within flexible strip  204 . 
     Although depicted as a fairly uniformly sized trace in FIG. 3, it should be understood that heater trace  312  may vary in width and/or thickness such that certain portions of heater trace  312  produce more heat than others. Moreover, heater trace  312  may be more than a conductive trace in that it may include electrically resistive materials and/or sections. For example, depending upon the shape/size of pen body  202 / 202 ′ and/or flexible strip  204 , there may be regions that need to reach a higher temperature to effectively reduce the formation of unwanted holes in sealing material  320 , and/or adequately thermally cure sealing material  320 . 
     FIG. 4 illustrates the application and curing of sealing material  320  between pen body  202  and flexible strip  204 , for example, as in FIG. 3, in accordance with certain exemplary implementations of the present invention. Here, a sealant applicator  400  is configured to apply sealing material  320  to flexible strip  204  and pen body  202 . As illustrated in the close-up, cross sectional view of the resulting sealing material interface, sealing material  320  has conformed to both flexible strip  204  and pen body  202 . In this exemplary implementation, sealing material  320  has flowed into and substantially filled the opening around heater trace  312 . 
     FIG. 5 is a similar illustrative diagram depicting the application and curing of sealing material  320  between a pen body  202 ′ and flexible strip  204 , in accordance with certain further exemplary implementations of the present invention. Here, pen body  202 ′ further includes a channel  500  that extends around at least a portion of pen body  202  and is configured to allow sealing material  320  to more easily flow into, around, and/or underneath the edge of flexible strip  204 . As illustrated, sealant applicator  400  can be positioned to an angle that allows for the sealing material to better flow into the region created by channel  500 . 
     Channel  500  provides several advantages. For example, channel  500  may allow sealing material  320  to have a lower profile. A lower profile helps allows for closer pen to paper spacing, which can be an important design objective in many printing devices. Channel  500  significantly addresses such design objectives, while also improving pen ink resistance and pen life. 
     Channel  500  or other like grooves or machined areas in pen body  202 ′ may increase the contact area of sealing material  320 , which provides several advantages, depending upon the pen body design. For example, increases in the contact area can improve adhesion of flexible strip  204  to pen body  320  and if possible cover layer  300 . This tends to further improve the ink resistance, which increases the operating life of the resulting pen. For example, channel  500  increases the path length that ink has to migrate through and around before it can harm the electrical traces, etc. 
     Channel  500  also allows sealing material  320  to be retained and or located in an improved manner. For example, as sealing material  320  is applied and heated by heater trace  312 , the viscosity of sealing material  312  usually changes and may present a problem if sealing material  320  moves to other unintended parts of pen body  202 / 202 ′. However, channel  500  tends to keep sealing material  320  where it was intended to be. 
     Channel  500  or other like features can also be designed so that trapped gases can be managed or routed as heater trace  312  heats up. Thus, instead of allowing expanding gases to seek an escape route, e.g., possibly through sealing material  320 , channel  500  can be designed to route the gases in a controlled fashion. 
     Channel  500  may further allow for more sealing material  320  to be applied. Basically, more bulk sealing material tends to make it harder for ink to migrate into the electrical traces, etc. In certain implementations, for example, the amount of sealing material  320  applied to pen body  202 ′ is about double the amount applied to pen body  202 . As a result of channel  500  the added amount of sealing material does not impinge on the pen to paper spacing and other mechanical envelope issues. 
     Channel  500  can also be useful in providing a strong perimeter attachment of flexible strip  204  to pen body  202 ′. In certain implementations, for example, portions of flexible strip  204  are mechanically wiped by a maintenance mechanism (not shown). Such wiping movement stresses and pushes on that portion of flexible strip  204 , typically in a cyclical fashion. This action may lead to premature failure of cover layer  300 . However, with the perimeter adhesive action of sealing material  320  the affected area of flexible strip  204  can remain anchored even if cover layer  300  fails. Those skilled in the art will recognize that in certain implementations, therefore, it may be possible to reduce the size of, or possible eliminate, cover layer  300 . 
     Furthermore, the low profile of sealing material  320  as a result of channel  500  will not interfere with such pen wiping actions or wipers while still providing ink resistance. 
     FIG. 6 is a flow diagram of a process  600  for providing an improved seal between pen body  202 / 202 ′ and flexible strip  204 , in accordance with certain exemplary implementations of the present invention. 
     In step  602 , flexible strip  204  is fixedly attached to pen body  202 / 202 ′, for example, using a cover layer  330  or other like adhesive material. At the same time and/or thereafter, heater trace  312  is preheated by passing an electrical current through it. This generates heat in and around the region that sealing material  320  is to be applied. In step  606 , following at least a portion of the preheating of step  604 , sealing material  320  is applied in such a manner as to form a seal between flexible strip  204  and pen body  202 / 202 ′. Next, in step  608 , sealing material  320  is thermally cured by continued application of electrical current to heater trace  312 . In certain implementations, the electrical current applied to heater trace  312  remains at about the same level through steps  604 - 608 . In other implementations, the amount of electrical current applied to heater trace  312  is selectively varied during steps  604 - 608 . In this manner, the thermal energy output of heater trace  312  can be controlled to provide an optimal sealing material application and/or curing environment. 
     FIG. 7 illustrates a top view of an exemplary non-opaque flexible strip  204 , in accordance with certain implementations of the present invention. As shown, a plurality of electrical circuit traces  302  and electrical contacts  304  are provided for operating a print cartridge. In this example, heater trace  312  extends about a portion of flexible strip  204 , between heater trace contact pad  314   a  and heater trace contact pad  314   b . When being preheated/heated, an electrical signal (e.g., a direct current (DC) signal) from a source  310  is applied through heater trace contact pads  314   a-b  and heater trace  312  there between. 
     To further illustrate the exemplary implementations described above, FIG. 8 pictorially shows two views of print cartridge  102  having flexible strip  204  fixedly attached to pen body  202 / 202 ′ and having a portion of flexible strip  204  that is sealed to a corresponding portion of pen body  202 / 202 ′, in accordance with certain implementations of the present invention. Here, as shown, sealing material  320  has been applied to the portions of flexible strip  204  and pen body  202 / 202 ′ associated with heater strip  312 . The resulting thermally cured sealing material  320  provides a seal that is not permeable to the liquids typically involved in the printing process. 
     FIG. 9 is a block diagram illustratively depicting a device  900  having two component parts  902  and  904  that include a thermally cured sealing material interface  908  there between and at least one heater trace  906  or like heating element, in accordance with certain further exemplary implementations of the present invention. Component parts  902  and  904  are representative of any types of components, materials, surfaces, etc., which are to have a seal formed there between using a thermally cured sealing material. Heater trace  906  is configured to provide the thermal energy associated with the thermally cured sealing process when an electrical signal is passed through it. While heater trace  906  is depicted nearby the edge of component part  904 , it should be understood that heater trace  906  may be placed in other regions of component part  904  and/or  902 . Heater trace  906  may be part of component part  904  and/or component part  902 . Additionally, one or more gas venting troughs or like features (not shown) can be provided in either component part  902  and/or component part  904  to provide a path for heated gases to escape from between the component parts without having to pass through the sealing material interface. 
     Thus, although some preferred implementations of the various methods and apparatus of the present invention have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it will be understood that the invention is not limited to the exemplary implementations disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the spirit of the invention as set forth and defined by the following claims.