JPH02301470A - Printing apparatus of thermal transfer printer - Google Patents

Abstract

PURPOSE:To obtain sharp printing without difference depending on printing paper, in performing lap-printing of printing lines, by changing the paper feed pitch at the time of printing at every paper by an integral multiple of the dot pitch of a thermal head corresponding to a change of the thickness of printing paper. CONSTITUTION:A proper paper feed pitch is set to standard paper corresponding to a paper thickness (s) so as not to generate a white line. When postcard paper 5 is printed, if a paper feed angle theta is same, shift is generated in the paper feed pitch by the effect of paper thickness difference (t) and the lap- quantity in one line is increased. Then, by altering a paper feed angle at the time of the printing of the postcard paper to set the same to theta1 smaller than theta, a paper feed pitch becomes same as the standard paper 4 and good printing generating no white line or printing shift is obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a printing method for a thermal transfer printer.

[Conventional technology]

In a serial type thermal transfer printer, a thermal serial head 3 with a 48-dot configuration as shown in Fig. 3(a) is used.
Taking this as an example, the No. 1 dot and the No. 48 dot exist on the upper and lower end surfaces of the thermal head row.

As a result, as shown in FIG. 3(b), the temperature rise in the heads at both ends is lower than that in the other heads.

Therefore, in the thermal serial method, color development is poor at the upper and lower ends of one print line. As shown in Figure 4, when graphic printing is performed with the print data and paper feed amount the same, the lower heat generation of the dots on both end faces causes the printed dots on the upper and lower ends to overlap with other printing. It is ejected very small compared to the dot.

Looking at the whole picture, as shown in Figure 4(a), when the printing pitch and paper feed amount are the same, a so-called hot line 7 occurs where the white of the printed paper is visible between the lines of printing. It is a known fact that

For this reason, as shown in Figure 5(a), the paper feed pitch of one printing line is made one dot shorter than the total length of the thermal head, that is, the printing pitch of one line is overlapped one dot at a time as a countermeasure against white lines. there was.

Alternatively, as shown in FIG. 5(b), there is also an example in which the paper feed pitch is overlapped by two dots at a time to take measures against white light.

When printing data for each line is overlapped in this manner, a dot pitch equivalent to 1 to 2 dots of the thermal head is appropriate.

As shown in this example, there has conventionally been a method that focuses on the heat generation characteristics of a thermal serial head and overlaps upper and lower printed dots in order to compensate for printing on the end face of the head, which has a poor heat output.

However, there have been no studies that have focused on the misalignment of printed images due to printing paper.

In addition, when multiple colors are layered, JP-A-63-12259
As shown in 5, when applying multiple colors in layers,
There is a printing method in which the dot pitch of the printing lines of each color is shifted in a stepped manner to prevent white lines.

However, in the conventional printing method as shown in Japanese Patent Laid-Open No. 63-122595, one to two dots in the printing line must be overlapped in order to obtain good printing due to the heat generation at the top and bottom ends of the head. has been proposed, but the thickness of the printing paper was not considered at all.

Furthermore, in an actual thermal serial head, the third
As shown in Figure 4(b), since the temperature rise of the head is low at the upper and lower ends of the head, as shown in Figure 4(b),
The printed dots at the upper and lower ends are smaller than other dots.

Therefore, the amount of ink peeled off from the thermal ribbon is also small.

Therefore, overlapping the upper and lower dots in one printing line means overlapping ink with a small amount of peeling, and even if multiple colors are overlapped, the printing does not take up much bulk when overlapping the upper and lower ends. This is unlikely to cause disturbances.

At the same time, the operation of shifting the paper feed pitch for each print color requires extremely complicated print data processing on both the printer side and the print data sending side.
It was extremely troublesome.

Currently, standard paper is generally established for individual printers, and appropriate pitch intervals that do not cause printing irregularities are set, so there was no problem.

However, when the printing paper is thicker than standard paper, such as postcard paper, a deviation in the printing pitch occurs.

In addition, due to the recent increase in the density of thermal heads, a high-resolution type head with a 48-dot type has appeared compared to the conventional 24-dot type, which has a coarser resolution. Although the misalignment has become more noticeable on the print data, the current situation is that the misalignment of the print on the printing paper is ignored.

[Problem to be solved by the invention]

The present invention deals with the increase in resolution of data and the change in paper feed pitch due to the increase in printer density due to the increase in the density of printers. The object of the present invention is to provide a printing method that can output a clear image without white lines very easily.

[Means to solve the problem]

In a thermal transfer printer, the present invention adjusts the paper feed pitch during printing by an integral multiple of the dot pitch of the thermal head in response to changes in the paper thickness of the printing paper when printing overlapping print lines. This is a printing method for thermal transfer printers that is characterized by the ability to change

[For production]

According to the above method of the present invention, in a thermal transfer printer,
Regardless of the printing paper, it is possible to relatively easily obtain clear printing that is compatible with high-density, mono-color and full-color printing, and has no difference depending on the printing paper.

〔Example〕

This method will be explained based on an example. FIG. 1(a) is a sectional view of the printer when printing on standard paper. 1 is a paper feed roller, 2 is a paper press roller, 3 is a thermal head, and 4 is a standard printing paper. The paper thickness of the standard paper at this time is S
shall be.

At this time, the paper feed amount for one print line is determined by the paper feed angle θ.

FIG. 1(b) shows the case where postcard paper 5 is printed.

The paper feed angle at this time is also θ. If the paper thickness of the postcard paper 5 is thicker than the standard paper 4 as t, then t+s is obtained.

The printing results at this time are shown in FIG. 2(a) and FIG. 2(b), respectively.

As shown in FIG. 2(a), for the standard paper 4, an appropriate paper feeding pitch is set corresponding to the paper thickness S so as not to generate a white line.

However, when printing on the postcard paper 5, if the paper feed angle θ is the same, the paper feed pitch will be misaligned due to the influence of the paper thickness difference t, resulting in one line as shown in FIG. 2(b). The amount of overlap inside increases.

FIG. 1(C) shows an example in which the paper feed angle is changed when printing postcard paper, and in this case, the paper feed angle is set to θ1, which is smaller than θ. As a result, as shown in FIG. 2(C),
As with the standard paper 4, the paper feed pitch allows good printing without white lines or printing misalignment.

Also, in order to match the paper feed pitch for printing, please refer to Figure 1 (
As shown in d), contrary to the case in Fig. 1(c), the paper feed angle is set to θ2, which is larger than θ, and the paper feed pitch is shifted further than the increase due to the increase in paper thickness, and when using standard paper 4. There is also a method of shifting the set pitch by an integral multiple of the dot pitch of the thermal head. An enlarged view of the printing result in this case is shown in FIG. 2(d).

〔Effect of the invention〕

According to the present invention, even when the thickness of the printing paper changes, the roller diameter of the paper feed roller R1 the difference in thickness from the standard paper 4 t1 the dot pitch value of the thermal head R-θ , paper feed pitch R・θ when paper thickness S changes
It is only necessary to set the amount of change so that it is an integer multiple of the dot pitch of the thermal head, and the printer side and the side that supplies data to the printer have to set the conditions to obtain a clear image print without dot pitch deviation. It has the advantage of being easy to obtain.

In addition, even when multiple colors of ink are overcoated, such as in full-color printing, this method eliminates the problems that actually occur mechanically.
Since it handles printing pitch deviations, if the paper thickness is properly managed, complex data operations such as shifting the printing pitch hierarchically for each ink, as shown in Japanese Patent Application Laid-Open No. 63-122595, can be performed. It is possible to easily obtain clear prints even if the paper thickness changes.

In addition, the resolution of thermal heads has recently increased, from the conventional 24 dots at 180 dpi or 160 dpi pitch to 4 dots at 300 dpi or 360 dpi pitch.
As the mainstream resolution has shifted to 8 dots, a situation has arisen in which printing pitch deviations, which were previously unnoticeable, are noticeable depending on the printing paper. This method has the advantage of being able to easily deal with such printing disturbances.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1(a) to 1(d) are sectional views in the paper feeding direction showing an embodiment of a thermal transfer printer according to the present invention. 2(a) to 2(d) are detailed views of printed dots when printed in the state shown in FIG. 1. FIG. 3(a) is an external view of a 300 dpt, 48 dot thermal printer head. FIG. 3(b) is a diagram showing the temperature distribution of each dot. FIG. 4 is a diagram showing a printing state when printed dots are not overlapped. FIG. 4(a) is a diagram showing how white lines are generated. FIG. 4(b) is an enlarged view showing the white line generation state. Further, FIGS. 5(a) to 5(c) are diagrams of overlapping printing set on standard paper 4 to suppress the occurrence of white lines. 1...Paper feed roller 2...Paper pusher roller 3...Thermal head 4...Standard paper 5...Postcard paper 6...Print dot 7...White line 7: Paulownia roller Figure 1Figure 1 (Q) (b) (d) Figure 2 (Q) (b) Figure 5

Claims (1)

[Claims] In thermal transfer printers, when printing overlapping print lines, the paper feed pitch during printing is changed for each paper by an integral multiple of the dot pitch of the thermal head in response to changes in paper thickness. A printing method for thermal transfer printers that is characterized by: