Ink ribbon cassette

Abstract: An ink ribbon cassette (1) includes a supply side ribbon spool (60), a take-up side ribbon spool (61), a cassette case (3,4) containing therein the supply side and take-up side ribbon spools and pivotably supporting at least the take-up side ribbon spool through a lever member (44) and having an opening through which an outside feed tooth (22) may mesh with the take-up side ribbon spool and further having a support portion (66) provided in the opening (65) for contacting the peripheral surface of the take-up side ribbon spool to prevent the take-up side ribbon spool from protruding outwardly, and biasing device (47) for imparting a rotational force to the lever member so that the take-up side ribbon spool is urged against the support portion.

Description: BACKGROUND OF THE INVENTION Field of the Invention This invention relates to an ink ribbon cassette adapted to be removably mounted with respect to a recording apparatus such as a printer and to contain an ink ribbon therein. Related Background Art Generally, an ink ribbon cassette contains therein a supply side ribbon spool and a take-up side ribbon spool for winding an ink ribbon thereon. There are available ink ribbon cassettes in which the take-up side ribbon spool is movable. Figure 5 of the accompanying drawings shows an example of the prior art. A supply side ribbon spool 201 and a take-up side ribbon spool 202 are contained in a cassette 200. Reference numerals 203 and 204 designate manually rotatable knobs. Feeding of the ribbon can be accomplished by holding these knobs. Figure 6 of the accompanying drawings shows a cross-section taken along line XX-XX of Figure 5. The take-up side ribbon spool 202 comprises a take-up core 205 and an ink ribbon wound thereon, and the manually rotatable knob 204 is formed above and integrally with the core 205. Such integral formation of the knob 204 with the core 205 is preferable in that the number of parts is reduced. However, if the knob 204 is formed integrally with the core 205, the diameter 207 of the knob 204 must be made smaller than the diameter 208 of a hole 206 for the purpose of assembly. Such a smaller diameter of the knob 204 leads to great difficulties in operation. A typical ink ribbon cassette is disclosed in the DE- 25 53 329. The take-up spool of this cassette is driven by a toothed drive means against which the take-up spool is urged by a biased lever. If in this cassettes the ink ribbon has to be wound further since, for instance, the transport of the ribbon formed loops or since certain portions of the ribbon do no longer contain enough ink after repeated use, the cassette has to be removed from the apparatus. Another comparable ink ribbon cassette is known from the AT-B-378 510. SUMMARY OF THE INVENTION It is the object underlying the subject matter of the application to produce a cassette in the case of which the ribbon can be wound further manually even if the cassette is inserted in the apparatus. According to the application the object is solved by the features defined in claim 1; in particular in that a central portion of the take-up spool projects from the cassette case and is provided with an actuating means, a winding further manually is at any time possible. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a plan view of the ribbon cassette with the upper case thereof partly broken away. Figure 2 illustrates the vicinity of an opening. Figure 3 illustrates the relation between a slit and a manually rotatable knob. Figure 4 is a cross-sectional view taken along line X-X of Figure 3. Figure 5 is a perspective view of an example of the prior art. Figure 6 is a cross-sectional view taken along line XX-XX of Figure 5. Figure 1 shows the ribbon cassette with the upper case thereof partly broken away. As shown, the ink ribbon drawn out from a supply roll 60 comprising the ink ribbon wound around the supply core 26 is guided by the guide pin 35 and is led outwardly past the guide arm 17 via the guide pin 55. The exposed ink ribbon is again led into the ribbon cassette through the guide arm 18 and is taken up by the take-up core 50 via the guide pin 55, thus forming a take-up roll 61. As shown, the tension means 29 is normally biased in a direction D by the coil spring 34. Thus, tension is imparted to the ink ribbon. In this state, as the ink ribbon is drawn out the tension means 29 is rotated in the direction opposite to the direction D because the knurled portion 28 of the supply core 26 is stopped by the pawl portion 43 of the lock pawl of the locking means 38. This operation in the direction opposite to the direction D results in the convex portion 37 pressing the guide portion 42 of the lock pawl 38, whereby the meshing engagement between the lock pawl 38 and the knurled portion 28 is released. When the meshing engagement between the pawl portion 43 and the knurled portion 28 is thus released, the supply core 26 becomes free to rotate so as to feed out the ribbon. Thereby the tension means 29 is rotated in the direction D and stops at a predetermined position. By the movement of the tension lever as described above, the ink ribbon is fed sequentially. On the other hand, the take-up spool 61 has its side engaged by 2 feed tooth and is taken up sequentially. At this time, the meshing force between the feed tooth and the take-up spool 61 is provided by the tension coil spring 47. Accordingly, the lever member 44 is normally biased in a direction E and the spool 61 is taken up in a direction H by the force of the feed tooth. By an increase in the amount of turns of the take-up roll 61, the lever member 44 is pivoted in the direction opposite to the direction E. The state in which the take-up roll 61 is not in meshing engagement with the feed tooth is shown in Figure 2. In Figure 2, reference numeral 65 designates an opening through which the feed tooth may mesh with the take-up roll 61. In the opening 65, there is formed a support wall 66 which contacts the upper end portion of the take-up roll 61 as viewed in the direction of the thickness thereof. This support wall 66 prevents the take-up roll 61 from being exposed outwardly through the opening 65. On the other hand, an elongated slit 67 is formed in the upper surface of the upper case 3. The manually rotatable knob 52 is exposed outwardly through this elongated slit 67. Figure 3 shows the relation between the elongated slit 67 and the manually rotatable knob 52 shown in Figure 2. As shown, the elongated slit 67 is formed in an arcuate shape having a shorter side c and a longer side d. The shorter side of the manually rotatable knob is a, and the longer side thereof is b. Here, a, b, c and d are in the relations that a < c, b > c and d > c, and the manually rotatable knob 52 can be fitted at a particular position in the elongated slit 67. Figure 4 shows a cross-section taken along line X-X of Figure 3. As shown, the manually rotatable knob 52 can be easily fitted into the elongated slit 67, and when the ribbon is to be taken up, the operability is high because the span b is sufficiently great.

Claims: An ink ribbon cassette, in the cassette case of which a supply roll (26, 60) is rotatably supported and a take-up roll (50, 61) is rotatably and slidably supported, wherein said take-up roll (50, 61) is urged, with its periphery, against a wall (66) of the cassette (1) by means of a biased element (47), the cassette (1) being provided with an elongated slit (67) and the take-up roll (50, 61) being engaged with a manually rotatable knob (52) which is able to rotate the take-up roll (50, 61) through the elongated slit (67), wherein the width of the slit (67) is shorter than the length of the longer side of said manually rotatable knob (52) and longer than the length of the shorter side of said manually rotatable knob (52), whereby the take-up core (50) of the take-up roll (50, 61) is movable along said slit. An ink ribbon cassette according to Claim 1, characterized in that said slit (67) is arcuately curved. An ink ribbon cassette according to Claim 2 or 3, characterized in that said take-up core (50) is provided at the tip end of a pivotable lever member (44) and said take-up core (50) is movable along the said slit (67). An ink ribbon cassette according to one of Claims 1-3, characterized by locking means (28, 38, 43) for locking the rotation of said supply roll (26, 60), and tensioning means (29, 34) for imparting tension to the ink ribbon between said supply roll (26, 60) and said take-up roll (50, 61).

Inventors: OHBA YASUO, SHIMOYAMA NOBORU, OHBA, YASUO, SHIMOYAMA, NOBORU
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1987
Main classification: B41J32
IPC codes: B41J35, B41J32, B41J33