JPH0343019Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ink ribbon cartridge for a thermal transfer printer, and particularly relates to an improvement of an ink ribbon guide roller.

[Conventional technology]

As shown in FIG. 2, the ink ribbon cartridge of a thermal transfer printer usually has a guide roller 3 in the middle of the path to send the printed ink ribbon 1 to the take-up roller 2 in order to make the ribbon run smoothly.
However, in the conventional ink ribbon cartridge, a guide roller 3 is provided as shown in Fig. 3.
was rotatably attached to a straight shaft 5 provided in the cartridge body 4 and having a substantially constant shaft diameter.

[Problem that the invention attempts to solve]

By the way, in thermal transfer printers, tension in the width direction of the ink ribbon is caused by deviations in parallelism that occur between the thermal head and the platen, or between the thermal head and the ink ribbon cartridge, or by partial contraction of the ink ribbon due to heat generated during printing. There is a problem of printing defects due to skewed feeding of the ink ribbon due to uneven balance, etc., and the conventional ink ribbon cartridge described above does not have this correction function. The present invention aims to solve the problem of printing defects by providing a guide roller with a function of correcting the skew of the ink ribbon.

[Means for solving problems]

The ink ribbon cartridge for thermal transfer printers of the present invention, devised to solve the above-mentioned problems, has a shaft diameter approximately from the base end to approximately the center of the shaft of the cartridge body, on which the ribbon guide roller is rotatably attached. The shaft part has a constant straight shaft part and a tapered shaft part whose shaft diameter gradually decreases from the approximate center part to the tip part, and a part corresponding to the tapered shaft part is formed in the center hole of the guide roller into which the shaft of the cartridge main body is inserted. The guide roller has a straight hole with a substantially constant inner diameter, and a tapered hole whose inner diameter gradually increases toward the end at the point corresponding to the straight shaft, and both ends of the guide roller have a bulging spherical surface. It is characterized by this.

〔Example〕

In the embodiment of the present invention shown in FIG. 1, an ink ribbon cartridge main body 4 is formed of ABS resin or the like, and a shaft diameter from a lower end base end to a substantially central part is formed at a predetermined position on the bottom surface 4a of the cartridge main body 4. The shaft 5 of the cartridge body 4 is integrally provided with a straight shaft portion 5a having a substantially constant diameter and a tapered shaft portion 5a whose shaft diameter gradually decreases from the approximately center portion to the upper end tip. In the center hole 6 of the guide roller 3 which is inserted and rotatably attached, the inner diameter of the part corresponding to the tapered shaft part 5b of the upper half of the shaft 5 is approximately constant, and the inner diameter is equal to the shaft diameter of the straight shaft part 5a of the shaft 5. Straight hole 6a set slightly larger
In addition, the straight shaft portion 5a of the lower half of the shaft 5
A tapered hole portion 6b whose inner diameter gradually increases toward the lower end is formed at a portion corresponding to the lower end, and a bulging spherical surface with a radius of curvature approximately half the axial length of the guide roller 3 is formed at both ends of the guide roller 3. This is characterized by the provision of portions 3a and 3a'.

[Action and effect]

The configuration of the present invention is as described above, and the guide roller is able to swing its both ends at a slight inclination with respect to the center line of the guide roller, centering on the approximate center of the axis of the cartridge body. ,
Even if the tension of the ink ribbon is uneven in the width direction, the guide roller tilts accordingly and acts to balance the tension of the ink ribbon. This prevents the ink ribbon from running skewed and prevents printing defects. It is effective in preventing occurrence.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the main part of the embodiment of the present invention showing the fitting structure of the shaft and guide roller provided in the cartridge body, Fig. 2 is a schematic plan view of the cartridge, and Fig. 3 is a conventional example. FIG. 2 is a sectional view of a main part showing a fitting structure between a shaft provided in a cartridge body and a guide roller, similar to FIG. 1; 1... Ink ribbon, 2... Take-up roller, 3
... Guide roller, 3a, 3a' ... Spherical part, 4
...Cartridge body, 4a...Bottom surface, 5...
Shaft, 5a...Straight shaft part, 5b...Tapered shaft part, 6...Center hole, 6a...Straight hole part, 6
b...Tapered hole.

Claims (1)

[Scope of utility model registration request] The shaft of the cartridge body to which the ribbon guide roller is rotatably attached has a straight shaft with a substantially constant shaft diameter from the base end to approximately the center, and a tapered shaft whose shaft diameter gradually decreases from the approximately center to the tip. In the center hole of the guide roller into which the shaft of the cartridge body is inserted, the portion corresponding to the tapered shaft portion is a straight hole portion with an approximately constant inner diameter, and the portion corresponding to the straight shaft portion is formed as a straight hole portion toward the end. An ink ribbon cartridge for a thermal transfer printer, characterized in that it has a tapered hole whose inner diameter gradually increases, and both ends of the guide roller have bulged spherical parts.