JPH0574846U - Image forming device - Google Patents

Abstract

(57) [Summary] [Object] To provide an image forming apparatus capable of preventing an occurrence of wrinkles during printing on an ink sheet and obtaining an image of high printing quality. [Structure] An elastic member 17 is provided which acts in a direction perpendicular to a winding shaft 5 of a supply roll 3 of the ink sheet 1 and in a direction counteracting the tensile force of the ink sheet 1 generated during printing.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an image forming apparatus that forms an image by transferring the ink of an ink sheet to a sheet by heat generated by a thermal head.

[0002]

[Prior Art]

 FIG. 4 is a sectional side view showing a conventional image forming apparatus disclosed in, for example, Japanese Patent Laid-Open No. 59-146882, and FIG. 5 is a sectional plan view of the same. In the figure, 1 is an ink sheet, 2 is a take-up roll of the ink sheet 1, 3 is a supply roll, 4 is a take-up core axis of the take-up roll 2, 5 is a supply-side core axis of the supply roll 3, 6 Is a platen roller, 7 is a thermal head, 8 is paper, 9-12 are core bearings, 13 and 14 are bearings that rotatably support the core bearings 9-12, 15 is a pinch roller, and 16 is a casing. It is the body.

Next, the operation will be described. The ink sheet 1 and the paper 8 are pressed against each other by the platen roller 6 and the thermal head 7, the ink sheet 1 and the paper 8 are conveyed by the rotation of the platen roller 6, and the thermal head 7 performs the recording operation. At this time, an ink sheet tension of P1 is generated by the winding force F1 applied to the winding roll 2, and an ink sheet tension of P2 is similarly generated by the back tension (anti-supply force) F2 applied to the supply roll 3. To do. The core bearings 9 to 12 are rotatably supported by bearings 13 and 14, but their positions are fixed. Therefore, the winding roll 2 and the supply roll 3 are also rotated in a fixed position.

[0004]

[Problems to be solved by the device]

 The conventional image forming apparatus is configured as described above, and most of this type uses the ink sheet 1 having a width corresponding to A4 size recording paper or more recording paper. Therefore, it is difficult to keep the parallelism between the platen roller 6 and the supply roll 3 constant due to variations in the dimensions of each component. Therefore, uniform tension cannot be obtained over the entire width of the ink sheet 1, and there is a problem that wrinkles occur in the ink sheet 1 and the image is broken.

The present invention has been made to solve the above problems, and it is possible to easily adjust the parallelism of the supply roll with respect to the platen roller and to hold and fix the adjusted parallelism. The purpose is to obtain an image forming apparatus.

[0006]

[Means for Solving the Problems]

 In the image forming apparatus according to the present invention, a spring force that opposes the back tension generated in the supply roll is applied to the core shaft of the supply roll.

[0007]

[Action]

 In this invention, the spring force of the elastic member is balanced with the back tension generated in the supply roll during printing, so that the parallelism of the supply roll with respect to the platen roller is maintained.

[0008]

【Example】

 Example 1. An embodiment of the present invention will be described below with reference to FIGS. In the figure, the same or corresponding parts as those of the above-mentioned conventional one are designated by the same reference numerals, and the description thereof will be omitted. In the figure, 17 is an elastic member that applies a force against the pulling force of the ink sheet 1 to the supply-side core shaft 5 of the supply roll 3, 18 is a spindle of the thermal head 7, and 19 is an ink sheet guide roller. Is. Among the core bearings 9 to 12, the core bearings 10 and 12 that rotatably hold the supply-side core shaft 5 are rotatably supported in the platen roller 6 direction. .

Next, the operation will be described. The ink sheet 1 and the paper 8 are pressed against each other by the platen roller 6 and the thermal head 7, the ink sheet 1 and the paper 8 are conveyed by the rotation of the platen roller 6, and the thermal head 7 performs the recording operation. At this time, an ink sheet tension of P1 is generated by the winding force F1 applied to the winding roll 2, and an ink sheet tension of P2 is similarly generated by the back tension (anti-supply force) F2 applied to the supply roll 3. To do. Further, a component force P3 in the direction of the platen roller 6 is generated by the ink sheet tension P2. Since the spring force of the elastic member 17 acting in the direction opposite to this component force P3 is substantially equivalent to the component force P3, the parallelism to the platen roller 6 is reproduced by the component force P3 and the spring force of the elastic member 17 in the actual printing state. Let

Example 2. Although the elastic member 17 employs the tension spring in the above embodiment, the elastic member 17 may be provided with a compression spring as shown in FIG.

[0011]

[Effect of the device]

 As described above, according to the present invention, since the elastic member is arranged on the supply-side core shaft of the ink sheet, the parallelism with respect to the platen roller can be directly and easily reproduced, and the wrinkle on the ink sheet is generated. The effect is that high quality image can be obtained.

[Brief description of drawings]

1 is a sectional side view showing a first embodiment of the present invention.

FIG. 2 is a plan sectional view of FIG.

FIG. 3 is a sectional side view showing a second embodiment of the present invention.

FIG. 4 is a sectional side view showing a conventional image forming apparatus.

5 is a cross-sectional plan view of FIG.

[Explanation of symbols]

 1 Ink Sheet 2 Winding Roll 3 Supply Roll 4 Winding Side Core Shaft 5 Supply Side Core Shaft 6 Platen Roller 7 Thermal Head 8 Paper 17 Elastic Member

Claims (1)

[Scope of utility model registration request] 1. An ink sheet and a sheet are interposed between a platen roller and a thermal head, the thermal head heats the ink sheet to transfer the ink of the ink sheet to the sheet, and the ink sheet and the sheet are sequentially conveyed. In the image forming apparatus, the supply roll of the ink sheet is provided with an elastic member that opposes the tensile force generated in the direction perpendicular to the winding core at the time of printing and has a spring force substantially equivalent thereto. A characteristic image forming apparatus.