JPH04209154A - Printer - Google Patents

Abstract

PURPOSE:To prevent wrinkles by setting the contact width of a pinch roller and a capstan roller smaller than the width of paper to be fed. CONSTITUTION:A head for printing at least on a paper 1, a platen roller arranged opposite to this head, and a capstan roller 4 and a pinch roller 5 for carrying the paper 1 are provided. At this time, the contact width of the pinch roller 5 and the capstan roller 4 is set smaller than the width of the paper 1 to be fed so as to reduce a difference between an internal and an external paper feeding amounts generated by deflection of the pinch roller 5 and the capstan roller 4 and to prevent generation of wrinkles.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a printer.

Conventional technology In recent years, with the development of personal computers and workstations, the printers that are peripheral devices for them are also becoming more color-based.In order to improve image quality and expand applications, not only smooth paper but also OHP sheets, coated paper, and plastics are being used. Printing on paper, cloth transfer sheets, etc. is also an essential element. However, these special papers often have a higher coefficient of friction than smooth paper, and are more likely to wrinkle during transportation.

A conventional thermal transfer color printer will be described below.

In the thermal transfer printer, as shown in FIG. 4(a), when the paper is first advanced, the paper 1 is advanced by the platen roller 2 and the paper feed roller 3.

Next, during printing, the paper 1 is gripped by the capstan roller 4 and the pinch roller 5 and rotated in the direction of the arrow, as shown in FIG. 2(b). At this time, the head 6 is pressed by the platen roller 2, and the platen roller 2 is idle clockwise due to the one-way clutch, and is rotated by the paper 1 by the feed amount of the capstan roller 4. In addition, 7
8 is a paper supply side roller, 8 is an ink film, 9 is a supply side roller of the ink film 8, and 10 is a winding side roller of the ink film 8.

Next, when the paper is fed forward, the capstan roller 4 and the pinch roller 5 rotate in the direction of the arrow while being gripped, as shown in FIG. At this time, the head 6 is located away from the platen roller 2, and the paper 1 is gripped by the platen roller 2 and the paper feed roller 3, and the platen roller 2, which is connected to the capstan roller 4 by a gear, moves counterclockwise. is driven by a one-sided clutch. In order to prevent the paper from sagging between the capstan roller 4 and the platen roller 2, the outer diameter of the platen roller 2 is slightly larger than the theoretical value, and the paper is fed several times more than the feed amount by the capstan roller 4. There is.

In the case of color printing, the operations shown in FIGS. 4(b) and 4(c) are performed for ink films of three colors, yellow, magenta, and cyan, thereby performing seven-color and full-color printing. Further, as for paper feeding, as shown in FIG. 5, the contact width Wl between the capstan roller 4 and the pinch roller 5 and the width W2 of the paper 1 to be transported are approximately the same width.

Problem to be Solved by the Invention However, with the above configuration, when the capstan roller 4 and the pinch roller 5 are brought into strong pressure contact, a deflection as shown in FIG. 6 occurs, and the pressure at parts A and B is and the difference in paper feed amount caused by the difference in the amount of rubber deformation.
Depending on the type of paper being transported, paper wrinkles 1a as shown in FIG. 7 may occur. To prevent deflection, make the rollers thicker (if the rigidity is increased, the gears, levers, etc. will hit them, and the load on the bearings will increase, so there are restrictions, and machining the rollers into a tassel shape may also be considered as a countermeasure) However, it was difficult to process, leading to increased costs.

The present invention solves the above problems.

Means for Solving the Problems In order to solve the above problems, the present invention makes the contact width between the pinch roller and the capstan roller smaller than the width of the paper being conveyed.

Effect: With the above structure, it is possible to reduce the difference in the amount of paper feed between the inside and outside caused by the deflection of the pinch roller and the capstan roller, and to prevent the occurrence of paper wrinkles.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a paper feed portion of a printer in which the pinch roller width is set relative to the paper width according to an embodiment of the present invention.

The paper 1 is sandwiched between the capstan roller 4 and the pinch rollers 11 whose contact width W3 with the capstan roller 4 is smaller than the transport paper width W4.
By printing in a reciprocating direction corresponding to yellow, magenta, and cyan of the ink film, the difference in paper feed amount between the pinch roller center E and both edges is reduced compared to the conventional method, and the image quality is improved without paper wrinkles. Excellent 7-color and full-color printing is possible.

The present invention basically enables high-quality printing without wrinkles on paper that has a higher coefficient of friction than normal smooth paper, such as coated paper 2 synthetic paper, plastic paper, and special paper such as cloth transfer sheets. .

FIG. 2 shows the optimal pinch roller width for the friction coefficient of paper, and it can be seen that the higher the friction coefficient is, the more susceptible the roller is to deflection, and the pinch roller width must be made smaller. In an actual experiment using a cloth transfer sheet, by setting the contact width between 60 and 70% of the paper width, it was possible to obtain printing without paper wrinkles or printing misalignment.

Further, as another embodiment of the present invention, even if the capstan 12 side is made smaller as shown in FIG. 3(a), or as shown in FIG.
) as in capstan roller 13. pinch roller 14
A similar effect can be obtained even if both widths are narrowed.

Effects of the Invention As described above, the present invention has the effect of preventing paper wrinkles by reducing the contact width of the pinch roller with the paper.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a paper feeding portion of a printer according to an embodiment of the present invention, FIG. 2 is a relationship diagram showing the relationship between paper mass coefficient and optimum pinch roller width, and FIGS. FIG. 4 is an explanatory diagram of the operation of a thermal transfer printer. FIG. 5 is a perspective view of a paper feeding section of a conventional printer. FIG. 6 is an explanatory diagram showing the principle of paper wrinkle generation. , FIG. 7 is a plan view showing the area where paper wrinkles occur. 1... Paper, 2... Platen roller,
4.12゜13・・・Capstan roller, 5,
11.14...Pinch roller, 6...
head. Name of agent: Patent attorney Haruaki Koebi and two others Figure 1
/-M paper 4-1 size χ Tan roller Figure 2 Optimum pinch roller width Figure 3 Figure 5 Figure 7

Claims (1)

[Claims] It has at least a head for printing on paper, a platen roller disposed opposite to this head, and a capstan roller and a pinch roller for conveying the paper, and the pinch roller and the capstan roller are connected to each other. A printer characterized in that the contact width is smaller than the width of the paper being conveyed.