Patent Application
20070147931
The invention relates to thermal printer cartridges.
A thermal printer prints images by transferring donor material from a donor ribbon onto a receiver medium. Typically this is done by selectively heating the donor ribbon to melt donor material while concurrently pressuring the donor ribbon against the receiver medium. In this way, melted donor material transfers from the donor ribbon to the receiver medium to form an image while unmelted donor material remains on the donor ribbon. Donor ribbon is typically connected between a supply spool, which initially carries a supply unused donor ribbon, and a take-up spool upon which used donor ribbon is wound. In operation, the take-up spool is rotated to draw donor ribbon from the supply spool and across the print head for use in printing.
The donor spool and take-up spool can be provided as independent rolls joined only by the donor web. Alternatively, the donor spool and take-up spool can be joined together by a structural framework to form a thermal donor cartridge. Such a thermal donor cartridge provides a rigid structure around the supply spool and the take-up spool that can be used to protect the donor ribbon from incidental contact and from contaminants and that also positions the supply spool and the take-up spool in a geometric relationship. A wide variety of thermal printer cartridge designs are known. Typically each thermal printer cartridge is designed to be used in one particular type of thermal printer.
As thermal printing has grown in popularity, particularly in consumer applications, there has been a demand for thermal printer cartridges that can hold larger amounts of donor ribbon. However, the design of such high quantity thermal printer cartridges creates unique design problems. One of the most difficult problems is the challenge of creating a low cost and high quality cartridge which can survive the sometimes torturous environment that a typical consumer will subject it to. This is because the relatively large supply of thermal donor ribbon in such a thermal donor cartridge increases the weight of the thermal donor cartridge, which in turn, substantially increases the kinetic energy that the cartridge must be able to dissipate during a fall or drop or other impact incident.
In particular, it will be appreciated that when the donor cartridge is subjected an impact load, a substantial shock wave permeates the donor cartridge. The energy from such a shock wave must be managed by the structures of the thermal printer cartridge in a way that allows the energy from an impact to be dissipated without non-elastic deformation of the thermal printer cartridge that could interfere with the use of a dropped thermal cartridge.
Accordingly, the design of a high load thermal printer cartridge is typically adapted to address this issue. One way in which this can be addressed is to provide a more rigid thermal donor cartridge which can be done by using materials such as metals or expensive, high modulus of elasticity materials to form the thermal donor cartridge or to form the thermal donor cartridge using large, heavy, stiff structural forms. Alternatively, energy absorbing features can be incorporated into the exterior of the donor cartridge such as by applying cushioning bumpers to the thermal donor cartridge. These methods however, increase the size, weight and cost of the thermal printer cartridge.
What is needed is a low cost thermal printer cartridge that is adapted to manage relatively high kinetic energy loads.
In one aspect of the invention, a thermal printer cartridge is provided. The thermal printer cartridge comprises: a supply housing having a drive end and a non-drive end; a take-up housing having a drive end and a non-drive end; a stiffening linkage joining the non-drive end of the supply housing to the non-drive end of the take-up housing to define a separation between them, the stiffening linkage being capable of elastic deformation to absorb a portion of an energy from an impact load; an elastically deformable linkage joining the drive ends, the elastically deformable linkage being adapted to elastically deflect following a first pattern and to absorb another portion of the energy from the impact load during the deflection. A damping linkage joins the drive ends, the damping linkage being adapted to elastically deform following a second deflection pattern that is different than the first deflection pattern and to absorb still another portion of the amount of energy from the impact load during such deformation, the damping linkage further being adapted to damp deflection of the elastically deformable linkage during a portion of the deflection thereof.
In another aspect of the invention, a donor ribbon cartridge is provided. The donor ribbon cartridge comprises: a supply housing having a donor ribbon supply spool therein with a supply of unused donor ribbon wound on the supply spool; a take-up housing in parallel with the supply housing, the take-up housing having take-up spool therein, the supply housing and take-up housing having openings to allow donor ribbon to pass from the supply spool to the take-up spool; a stiffening linkage linking one end of the supply housing to an adjacent end of the take-up housing, the stiffening linkage capable of being resiliently deflected in to absorb a portion of an energy from an impact load, the deflection allowing the opposite ends of the supply housing and take-up housing to move between a range of positions relative to each other; and a shock absorber and spring linking the opposite ends of the supply housing and take-up housing the spring deflecting to absorb another portion of the energy from the impact load, and the shock absorber damping the deflection of the spring to absorb still another portion of the energy from the impact load.
In still another aspect of the invention, a thermal printer cartridge is provided. The thermal printer cartridge comprises: a supply housing having a supply spool with unused donor ribbon wound thereon and an opening through which donor ribbon can travel to a take-up spool; a take-up housing having the take-up spool therein and an opening to permit the donor ribbon to enter the housing; a first linkage for holding a first end of the supply housing and first end of the take-up housing within a first range of separation relative to each other, the first linkage being elastically deflectable to permit movement with the first range of separation and to absorb one portion of an energy from an impact load during the elastic deflection; a second linkage for holding a second end of the supply housing and second end of the take-up housing within a second range of separations relative to each other, the second linkage being elastically deflectable to permit variation of the separation within the second range of separation and to absorb another portion of the energy from a impact load during the elastic deflection; the second range of separation being larger than the first range of separation; and a linkage at the second end of the supply housing and the second end of the take-up housing for holding a second end of the supply housing and second end of the take-up housing within the second range of separations relative to each other, the third linkage being elastically deflectable in a manner that is different from the manner of deflection of the second linkage to that dampens the second linkage and absorb still another portion of the energy from an impact load.
Thermal printer cartridge 20 also has a take-up housing 52 with a drive end 54 and a non-drive end 56. Take-up housing 52 defines a take-up area 58 and bearing surfaces 60 and 62 that are adapted to receive a take-up spool 68 that is connected to donor ribbon 42. As is illustrated in
The supply housing 22 and take-up housing 52 are joined at the ends thereof by elastically deflectable linkages. These elastically deflectable linkages include a stiffening linkage 70, an elastically deformable linkage 80 and a damping linkage 90. In the embodiment of
Elastically deformable linkage 80 joins and defines drive end separation S2 between drive end 24 of supply housing 22 and drive end 54 of take-up housing 52. Elastically deformable linkage 80 is elastically deflectable in a manner to allow variation in the drive end separation S2. Such elastic deflection of elastically deformable linkage 80 absorbs another portion of the energy from an impact load.
Damping linkage 90 also joins drive end 24 of supply housing 22 to drive end 54 of take-up housing 52 and helps elastically deformable linkage 80 to define separation S2. Damping linkage 90 is defined in a manner so that damping linkage 90 elastically deforms in a different pattern than elastically deformable linkage 80. This difference in deflection patterns causes damping linkage 90 to act as a damper on the deflection of elastically deformable linkage 80.
Stiffening linkage 70 provides relatively stiffer beam strength than the combination of elastically deformable linkage 80 and damping linkage 90 provide. This relatively stiff connecting beam provides the majority of the structural integrity for thermal printer cartridge 20. Stiffening linkage 70, however, is not rigid along all axes, and can be elastically deformed to permit deformation of the deformable linkage 80 and/or damping linkage 90. This permits wide variations in drive end separation S2 as compared to the variations in first separation S1 which are limited by the relatively stiff beam strength of stiffening linkage 70. As noted above, a portion of the energy from an impact load can be absorbed in elastically deforming stiffening linkage 70.
It will be appreciated that a portion of the energy from an impact load applied to thermal printer cartridge 20 that is absorbed to induce deflection of stiffening linkage 70, deformable linkage 80 and/or damping linkage 90 will be dissipated in the form of heat and that a portion of the energy will be stored in the form of potential energy. Portions of the energy that are stored as potential energy are released as the impact energy begins to drop off. A decay cycle can then begin with stiffening linkage 70 acting effectively as a leaf spring, with deformable linkage 80 acting as would a compression spring and with damping linkage 90 acting as a shock absorber or damper on the action of either or both of stiffening linkage 70 and deformable linkage 80. As will be discussed in greater detail below, at some points in the decay cycle, portions of the potential energy will be held in a deflected stiffening linkage 70, with a portion this potential energy being released by stiffening linkage 70 in the form of kinetic energy that induces potential energy storing deflections at elastically deformable linkage 80 and damping linkage 90 and with a portion of the released potential energy being dissipated. At other times in the decay cycle, potential energy will be held in a deflected elastically deformable linkage 80 and damping linkage 90 with a portion of this potential energy being released to induce a deflection in stiffening linkage 70 and a portion of this released potential energy being dissipated. With each transfer of energy, a portion of the impact energy is dissipated until all of the impact energy is so dissipated.
Because at any given time, a portion of the energy from the impact load is held in the form of potential energy and because this potential energy is repeatedly transferred between different members over the time period required to dissipate the energy, thermal printer cartridge 20 can dissipate the energy from a impact load over a relatively long period of time and in a more controlled manner. This mitigates against causing non-elastic deformation any component of thermal printer cartridge 20.
As is shown in
Further, as shown in
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
