Printer ribbon cassette mounting apparatus

Abstract: A printer ribbon cassette mounting apparatus includes a pair of aligning posts (38,40) and a pair of resilient latch members (52,54) mounted on a lower surface of the cassette housing (20). The posts and latch members engage complementary slots (84,86); (88,90) respectively in wall portions (72,74) of the printer with which the cassette (20) engages. Two restrainers (64,66) extend from the lower surface of the cassette (20) in parallel spaced relation to the latch members (52,54), and prevent excessive bending of said latch members (52,54). The latch members (52,54) are provided with first and second camming surfaces (60,62). The first camming surfaces (62) cooperate with a corresponding wall portion (72,74) to push the resilient latch members (52,54) to one side when mounting the cassette (20) on the printer. The second camming surfaces (60) then engage said slots (88,90) in the wall portions (72,74) to secure the cassette (20), and cooperate with an upper edge of said slots (88,90) to push the resilient latch members (52,54) to one side to disengage the latch members (52,54) from said slots (88,90) for removal of said cassette (20) from the printer.

Description: This invention relates to printer ribbon cassettes, and more particularly relates to apparatus for mounting a printer ribbon cassette on a printer. In present day printers, it is common practice to use a ribbon cassette carrying an endless ribbon which is caused to be driven past the printing station with the ribbon being either a pre-inked ribbon or a ribbon which is to be continuously or frequently re-inked during the printing operation. The ribbon cassette may be of the stuffing box type, wherein the ribbon is contained within the cassette in random manner and the ribbon is unfolded at the cassette exit and is caused to be driven past the printing station and then trained to enter the cassette to be folded in random manner therein. A ribbon may be utilized in a mobius loop configuration wherein the ribbon is in substantially continuous contact with an inking core or the ribbon may have a plurality of coils around a core for controlled inking thereof. Ribbon cassettes are relatively inexpensive and easy to manufacture. For example, they may be injection-molded from plastic. They must be periodically replaced on printers to provide a fresh ribbon for printing. It is therefore important that a ribbon cassette can be quickly installed on, and removed from, a printer without the need for special tools, and without an operator having to come into contact with the ribbon, which could cause a staining of fingers or clothing. Various types of devices have been utilized for securing a ribbon cassette to a printer, including magnetic latches and snap-type latches. One example of securing a ribbon cassette is shown in US Patent numbered 4,408,914. The mounting assembly shown therein includes a printer ribbon cassette having a resilient cantilevered tab. The tab has a stepped surface which is arranged to engage an aperture in a mounting bracket to hold the cassette in position. The cassette has a pair of guide pins which engage openings in the mounting bracket. To remove the cassette from the printer, the tab has to be disengaged manually from the mounting bracket so that the cassette can be lifted out from the printer. An object of the present inveniton is to provide a printer ribbon cassette mounting apparatus which is simple, inexpensive and effective. Another object of the invention is to provide a printer ribbon cassette mounting apparatus which includes resilient latch elements mounted on the cassette housing and adapted to engage cooperating supports on the printer in a manner which assists the fitting of the cassette to the printer, and the removal of the cassette from the printer. Another object of the invention is to provide a printer ribbon cassette mounting apparatus which includes aligning elements and resilient latch elements on the cassette housing and engageable with cooperating supports on the printer and also includes restraining elements located adjacent to the latch elements for preventing excessive bending of the latch elements. According to the present invention there is provided a printer ribbon cassette mounting apparatus for mounting a printer ribbon cassette on a printer, said apparatus including cassette support means, and a printer ribbon cassette, said cassette having alignment means and resilient latching means projecting therefrom; said cassette support means including first reception means for receiving said alignment means, and second reception means for receiving said resilient latching means, whereby said cassette is aligned and held on said printer, said resilient latching means including first camming means for cooperation with said cassette support means for deflecting said resilient latching means, during mounting of said cassette on said printer, until said resilient latching means are secured within said second reception means, characterized in that said resilient latching means extend from said cassette generally in a direction parallel to the direction in which said cassette is moved when being mounted on said printer, and said resilient latching means includes second camming means arranged to cooperate with said cassette support means for holding said cassette in position on said printer and for causing said resilient latching means to deflect and disengage from said second reception means when an appropriate force is applied to said cassette urging said cassette away from said printer. According to the present invention there is provided a printer ribbon cassette for mounting on a printer, and including first and second main surfaces, characterized by first and second resilient latching members projecting perpendicularly away from one of said main surfaces and being respectively located adjacent opposite side surfaces of said cassette, each of said latching members being provided with outwardly facing first and second cam surfaces, said first cam surfaces being adapted to cooperate with first edges of cassette support means for deflecting said latching members, during mounting of said cassette on said printer, to enable said latching members to become secured to said cassette support means, and said second cam surfaces being adapted to cooperate with second edges of said cassette support means for holding said cassette in position on said printer and for causing said latching members to deflect and disengage from said second edges when an appropriate force is applied to said cassette urging said cassette away from said printer. The present invention provides apparatus for mounting a ribbon cassette on a printer in a manner which advantageously permits easy installation and removal of the cassette and which is inexpensive to manufacture and is reliable in operation. An embodiment of the present invention will now be described with reference to the accompanying drawings in which: Fig. 1 is a front view of a ribbon cassette constructed in accordance with the present invention; Fig. 2 is an end view of the cassette, taken along line 2-2 in Fig. 1; Fig. 3 is a bottom view of the cassette of Fig. 1; Fig. 4 is an enlarged fragmentary sectional view of a latch element and an associated restraining element on the cassette, taken on line 4-4 of Fig. 3; Figs. 5, 6 and 7 are side, front and bottom views, respectively, of an aligning element which forms part of the cassette; Fig. 8 is an exploded perspective view showing the manner in which the latching and aligning elements of the cassette cooperate with complementary structure on supports which form a part of the printer with which the cassette is used. Referring now to Figs. 1, 2 and 3, shown there is a printer ribbon cassette 20, having an upper surface 22, a lower surface 24, a right side surface 26, a left side surface 28, a front surface 30 and a rear surface 32. Two ribbon guide arms 34 and 36 extend from the side surfaces 26 and 28, respectively, to guide a ribbon 37, shown fragmentarily, out of the body of the cassette 20, along one of the guide arms, on a straight-line path between the ends of the two ribbon guide arms into operative relation with a print station (not shown) of an associated printer, and back along the other of the guide arms into the body of the cassette 20. For proper operation of the printer, it is necessary that the cassette 20 be properly positioned on and secured to the printer, so that the ribbon 37 is disposed in proper alignment with the print station of the printer. This is accomplished by providing the cassette 20 with securing means which locate it precisely with respect to a part of the structure of the printer. A pair of alignment posts 38 and 40 extend downwardly from the lower surface 24 of the cassette 20 adjacent to the side surfaces 26 and 28, respectively. These posts are identical, and post 38 is seen in greater detail in Figs. 5, 6 and 7. As shown there, the post 38 is of generally U-shaped cross-section, having two sides 42 and 44 joined by an integral rear portion 46. The sides 42 and 44 are partially cut away, with rounded edges, as shown at 48, to provide a reduced lower portion 50. The cut-out portion 48 of the posts 38 and 40 cooperates with a complementary portion of the printer structure, as will be subsequently described, to align the cassette 20 on the printer. The cassette 20 is secured to the printer by a pair of depending identical latch members 52 and 54 which are molded integrally with the cassette housing, and which extend downwardly from the lower surface 24 of the cassette 20. Each latch member 52 and 54 is located adjacent to one of the side surfaces 26 and 28, and also adjacent to the front surface 30. As can best be seen from the sectional view of Fig. 4, the latch member 52 includes an upper resilient blade portion 56, which has a springy characteristic by virtue of the plastic material from which it is formed, and an enlarged lower portion 58. The portion 58 includes an upper convexly curved surface 60 and a lower angled surface 62. As will subsequently be described in greater detail, the surfaces 60 and 62 perform camming functions when the cassette 20 is being secured to and removed from the printer. Located adjacent to the latch members 52 and 54 and positioned inwardly thereof on the lower surface 24 are two restrainers 64 and 66. These restrainers extend downwardly from the lower surface 24 and may be molded integrally therewith. Each restrainer includes a vertical wall 68 which is spaced from and located parallel to the blade portion 56 of an associated latch member 52 or 54, and a reinforcing buttress 70 of triangular configuration which is molded integrally with the lower surface 24 and the wall 68 and extends between the two at right angles to both. The restrainers 64 and 66 limit the extent of inward bending movement of the associated latch members 52 and 54 which is permitted, and thus prevent the possible breakage of these members which might otherwise result from excessive bending. Referring now to Fig. 8, shown there is a perspective view of the cassette 20 in position to be attached to two wall portions 72 and 74 of the printer. Reinforcing members 75, attached to the wall portions 72 and 74, provide rigidity to these wall portions. The remainder of the printer structure is not shown, since it is not pertinent to an understanding of the present invention, but it may be noted thai the cassette 20 will be so positioned, when installed on the printer, that the ribbon 37 which extends between the ribbon guide arms 34 and 36 will be in cooperative relation to the print head of the printer so as to enable ink from the ribbon to be applied to the paper being printed upon during a printing operation. At its upper end, the wall portion 72 is provided with a horizontal edge 76 and a vertical edge 80. The wall portion 74 is provided with similar edges 78 and 82. These edges support the cassette 20 when said cassette is latched into operative position on the printer. The surfaces 76 and 78 are provided with notches 84 and 86 to receive the aligning posts 38 and 40 when the cassette 20 is positioned on the wall portions 72 and 74, and function to locate the cassette precisely on said wall portions. The wall portions are also provided with slots 88 and 90, each of which receives one of the latch members 52 and 54 to latch the cassette 20 in place on the wall portions 72 and 74. It will be seen that as the cassette 20 is moved downwardly onto the wall portions 72 and 74, the enlarged portion 58 of each of the latch members is moved inwardly by engagement of the angled surface 62 with the wall surface. The latch members 52 and 54 remain in their flexed positions as the cassette moves downwardly until the enlarged portion of each reaches its respective slot 88 and 90, at which time it snaps outwardly, locking the cassette 20 into position with the convexly curved surface 60 of each latch member 52 and 54 cooperating with an upper edge of a respective slot 80 and 90. At the same time, the alignment posts 38 and 40 engage the notches 84 and 86 to provide precise positioning of the cassette 20. When it is desired to remove the cassette 20 for replacement, upward pressure is exerted upon it. This causes the convexly curved surfaces of the enlarged portions of the latch members 52 and 54 to engage the upper edges of the slots 88 and 90 and to cam the enlarged portions inwardly. The cassette 20 may now be lifted out of engagement with the wall portions 72, 74, and may be replaced with a new cassette. While the form of the invention shown and described herein is admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to confine the invention to the form or embodiment disclosed herein, for it is susceptible of embodiment in various other forms within the scope of the appended claims.

Claims: A printer ribbon cassette mounting apparatus for mounting a printer ribbon cassette on a printer, said apparatus including cassette support means (72,74), and a printer ribbon cassette (20), said cassette (20) having alignment means (38,40) and resilient latching means (52,54) projecting therefrom; said cassette support means including first reception means (84,86) for receiving said alignment means, and second reception means (88,90) for receiving said resilient latching means, whereby said cassette is aligned and held on said printer, said resilient latching means including first camming means (62) for cooperation with said cassette support means (72,74) for deflecting said resilient latching means, during mounting of said cassette on said printer, until said resilient latching means are secured within said second reception means (88,90), characterized in that said resilient latching means extend from said cassette (20) generally in a direction parallel to the direction in which said cassette is moved when being mounted on said printer, and said resilient latching means includes second camming means (60) arranged to cooperate with said cassette support means for holding said cassette in position on said printer and for causing said resilient latching means to deflect and disengage from said second reception means (88,90) when an appropriate force is applied to said cassette urging said cassette away from said printer. An apparatus according to claim 1, characterized in that said latching means comprise two latching members (52,54), respectively positioned adjacent opposite edge surfaces of said cassette. An apparatus according to claim 2, characterized in that said latching members (52,54) respectively include two protruding means (58) respectively having a convexly curved surface forming said second camming means, each of said curved surfaces cooperating with a respective edge of said second reception means (88,90) for the purposes of holding said cassette (20) on said printer and for disengaging said latching members from said second reception means when said force is applied to said cassette. An apparatus according to claim 2 or claim 3, characterized in that said cassette (20) has two restraining members (64,66) projecting therefrom, said restraining members being respectively located adjacent said latching members (52,54) to prevent excessive deflection of said latching members. An apparatus according to claim 4, characterized in that each restraining member (64,66) includes a planar portion (68) positioned parallel to the adjacent latching member, and a reinforcing portion (70) for supporting said planar portion. An apparatus according to any preceding claim, characterized in that said alignment means (38,40) includes a recessed portion (48) for engagement with said first reception means (84,86). A printer ribbon cassette for mounting on a printer, and including first and second main surfaces (22,24), characterized by first and second resilient latching members (52,54) projecting perpendicularly away from one (24) of said main surfaces and being respectively located adjacent opposite side surfaces (26,28) of said cassette, each of said latching members being provided with outwardly facing first and second cam surfaces (62,60), said first cam surfaces being adapted to cooperate with first edges (76,78) of cassette support means (72,74) for deflecting said latching members, during mounting of said cassette (20) on said printer, to enable said latching members to become secured to said cassette support means, and said second cam surfaces being adapted to cooperate with second edges of said cassette support means for holding said cassette in position on said printer and for causing said latching members to deflect and disengage from said second edges when an appropriate force is applied to said cassette urging said cassette away from said printer. A printer ribbon cassette according to claim 7, characterized by first and second restraining members (64,66) projecting from said one (24) of said main surfaces and being respectively located adjacent to, and spaced inwardly from, said first and second resilient latching members (52,54) to prevent excessive deflection of said resilient latching members.

Inventors: DALEY PHILLIP BRUCE, LEE JAMES WESLEY, DALEY, PHILLIP BRUCE, LEE, JAMES WESLEY
Applicants: NCR INT INC, NCR INTERNATIONAL INC.
Application year: 1991
Main classification: B41J32
IPC codes: B41J17, B41J35, B41J32