JPH02215549A - Thermal transfer printing machine - Google Patents

Abstract

PURPOSE:To print a straight line without steps by delaying a timing to print dots of one line for every group corresponding to the specific amount of deviation in arrangement of heat generating parts and the paper feed speed. CONSTITUTION:Heat generating parts 9 of each heat generating body are aligned with right angles to a paper feed direction, with a distance P kept between the adjacent heat generating parts. A plurality of the heat generating bodies are divided into N groups. The heat generating bodies 38-44 are shifted DELTAl=P/N from the heat generating bodies 45-51 in a moving direction of a paper 1, namely, in a direction shown by an arrow C. A delay time determined corresponding to the shifting amount P/N of the heat generating bodies 45-51 and 38-44 and the paper feed speed is given to corresponding drivers 24-30 for the heat generating bodies 38-44 forming a first group by a delay circuit 8.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a thermal transfer printing device that improves printing quality by dividing the heating element of a line thermal head into a plurality of groups and supplying current in a time-sharing manner. The purpose of this is to arrange multiple heating elements in a direction perpendicular to the paper feeding direction so that the distance between adjacent heating elements is P, and to apply energy to each heating element. Using a line thermal head that prints one line of dots on paper by generating heat as it is supplied, the paper is continuously moved so that the distance to the next printed line is P. A thermal transfer printing device that prints characters, figures, etc. by feeding paper, in which the plurality of heating elements of the line thermal head are divided into N groups, and the heat generating parts of the heating elements in each group are aligned in the paper feeding direction. , the heat-generating portions are shifted by P/N, and the N
The configuration is such that the supply timing of energy supplied to print one line of dots is shifted for each group.

[Industrial application field]

The present invention relates to a thermal transfer printing device using a line thermal head, and particularly to a thermal transfer printing device that improves printing quality by dividing the heating element of the line thermal head into a plurality of groups and supplying current in a time-sharing manner. Related to printing devices.

Because line thermal heads are quiet when printing, they are used in thermal transfer printing devices such as facsimiles and line printers used in offices and the like.

This line thermal head has hundreds to thousands of heating elements lined up, and by controlling the energization of each heating element, each heating element generates heat, melting the ink on the ribbon and depositing dots on the paper. By transferring or heating the thermal paper to form dots, one line of dots is simultaneously formed on the paper, and the paper is continuously fed.
It is designed to print characters, figures, etc. on paper at high speed.

By the way, in order to print a line formed by connecting one line of dots, it is necessary to simultaneously supply current to hundreds to thousands of heating elements so that each heating element generates heat at the same time. Due to the structure of the thermal head, it is difficult to supply the same current to each heating element at the same time, and the temperature of each heating element becomes non-uniform, resulting in uneven printing density.

In order to eliminate this concentration unevenness, multiple heating elements are divided into multiple groups and current is supplied at different timings.
Efforts have been made to reduce the difference in the current values supplied to each heating element, but as a result, a step is generated in a straight line perpendicular to the paper feeding direction.

However, the occurrence of such level differences degrades printing quality and is unsightly, so it is necessary to prevent them.

[Conventional technology]

FIG. 4 is a block diagram illustrating an example of the prior art.

In the conventional line thermal head, a plurality of heating elements 2 are arranged in a line in a direction perpendicular to the paper feeding direction, that is, in the direction of arrow A-B, and a driver 6 is connected to each heating element 2 through a drawer pattern 4. There is. Further, the heating element 2 is connected to a power source 7 via a common pattern 3.

Here, when the driver 6 is turned on for a predetermined time and current is supplied from the power source 7 to the heating elements 2, each heating element 2 to which the current is supplied generates heat, forming a dot 5 shown by a dotted line on the paper l. let

That is, when using a ribbon, the heating element 2 generates heat, which melts the ink on the ribbon and creates 5 dots on the paper 1.
If the paper 1 is thermal paper, dots 5 are formed on the paper 1 as the heating element 2 generates heat.

Therefore, when the driver 6 supplies current to all the heating elements 2, the dots 5 are formed in a line in the direction of the arrow A-B as shown in the figure, and each dot overlaps, so the - line is Printed on paper 1.

Paper 1 is continuously fed in the direction of arrow C,
The driver 6 is turned on for a predetermined period of time and then turned off.
Subsequently, it is turned on at the timing of forming the next dot in accordance with the paper feed speed, and current is supplied to the heating elements 2 necessary for printing characters and figures.

The distance between the next dot to be formed and the dot formed before it is generally printed so that it is equal to the distance @P between adjacent heating elements 2, so it depends on the paper feed speed. On/off of the driver 6 is controlled.

When printing a straight line by forming a line of dots in the direction of arrow A-B as described above, the driver 6 is turned on and current is supplied to all the heating elements 2 at the same time. The supplied current value increases and common pattern 3
A voltage drop occurs. Therefore, a difference occurs in the amount of energy supplied to each heating element 2, so that the amount of heat generated is not the same, and a density difference occurs in the dots formed on the paper 1.

That is, since hundreds to thousands of heating elements are lined up in the negative column and current is supplied to them at the same time, the current flowing through the common pattern 3 becomes a large value. Therefore, as in this example, the dots formed by the heating element 2 on the arrow B side, which is most affected by the voltage drop in the common pattern 3, are the thinnest, and the dots formed by the heating element 2 on the arrow A side, which is least affected by the voltage drop in the common pattern 3, are the thinnest. The dots formed by the heating element 2 are the darkest.

To avoid such effects, conventionally multiple heating elements were
By dividing the power into groups of 1 and staggering the timing of turning on the driver 6 for each group, the current value flowing through the common pattern 3 is reduced, the voltage drop is reduced, and the current is supplied to each heating element 2. The difference in energy amount is reduced.

[Problem to be solved by the invention]

FIG. 5 is a diagram illustrating the problems of the prior art.

As described above, if the timing at which the driver 6 is turned on is shifted to create a difference in the start time of the current supply to the heating element 2, the paper feed amount corresponds to this time difference, since the paper 1 is continuously moved. , a step occurs in a straight line perpendicular to the paper feeding direction.

That is, as shown in FIG. 5, if the paper feed amount is taken in the direction of the arrow, if a plurality of heating elements are divided into two groups, the first
The center line (■) of the dot row formed by the heating elements of the group and the center line (■) of the dot row formed by the heating elements of the second group correspond to the difference in the start time of current supply to the heating elements of the second group. There is a problem in that the printing quality deteriorates and is unsightly due to the amount of deviation and the occurrence of a step difference.

In view of these problems, the present invention makes it possible to print straight lines without steps when dividing the heating element of a line thermal head into a plurality of groups and setting different start times of current supply to each group. The purpose is to improve print quality and prevent it from becoming unsightly.

[Means to solve the problem]

FIG. 1 is a diagram illustrating the present invention in detail.

As shown in FIG. 1(a), the heat generating parts 9 of each heat generating element of the line thermal head are arranged in a direction perpendicular to the paper feeding direction shown by arrow C so that the distance between the heat generating parts of adjacent heat generating elements is P. are placed side by side. The plurality of heat generating elements are divided into N groups, and the heat generating portions 9 of each group are shifted by Δff1=P/N with respect to the paper feeding direction. In FIG. 1(a), N=2 and the case is shown where the lens is divided into a first group and a second group.

When current is simultaneously supplied to each heating element of the line thermal head configured in this way, dots are formed on the paper at the positions shown in ■ and ■ in Figure 1 (b), and a step is formed. A straight line with is printed.

In order to eliminate this level difference, the amount of deviation Δ in the arrangement of the heat generating parts 9 is
Corresponding to f=P/N and the paper feed speed, the energy supplied to print one line of dots for each group of N, that is, the supply timing of the current, is shifted and supplied.

In other words, the center line ■ of the dot row ■ printed by the first group of heating elements
Current is supplied to the second group of heating elements at the timing when the position reaches the position of the center line (2) of the dot row (2) to be printed by the second group of heating elements by paper feeding in the direction shown by arrow C.

By doing this, a straight line with no steps is printed, like the row of dots lined up on the center line ■ in Figure 1 (with), and when the paper is fed by the printing pitch P, the next row of dots is printed. .

This printing pitch P is the same as the distance P between the heat generating parts of adjacent heat generating elements as described above.

[Effect]

With the above configuration, the heating elements of the line thermal head divided into a plurality of groups have timings determined for each group in accordance with the displacement amount P/N of the heat generating portion 9 and the paper feeding speed. Since a current is supplied by this, it is possible to perform high-quality printing without causing density unevenness or unevenness.

〔Example〕

FIG. 2 is a block diagram illustrating an embodiment of the present invention.

FIG. 2(a) shows an example of a line printer, in which the processor 11 operates by reading out a program stored in the ROM 12, and upon receiving print data sent from the host device via the interface circuit 14, stores it in the RAM 13. ,
The print data stored in the RAM 13 is read out, and based on instructions included in the print data, the drawing circuit 15 is instructed to draw data such as characters and figures in the print data in one page on the bitmap memory 16. Let it unfold.

When the data for one page is developed on the bitmap memory 16, the processor 11 controls the readout circuit 17 via a control line (not shown) to scan the bitmap memory 16 by raster, and the data for 1,547 pages is expanded. The data is read out from the line thermal head 1 via the head control circuit 18.
9 to print one line of data in synchronization with rask scanning.

At this time, the processor 11 drives the line feed motor 21 via the line feed control circuit 20 to perform sheet feeding that continuously moves sheets (not shown) at a constant speed.

Further, when the processor 11 completes printing one page,
After controlling the approach/escape control circuit 22 to drive the motor 23 to perform an escape operation to move the line thermal head 19 off the paper, the line feed control circuit 2
0, the line feed motor 21 is driven to eject the paper.

Then, when the next paper to be printed is transported and the next paper is set at the printing position, the approach/escape control circuit 22 is controlled again to drive the motor 23 and bring the line thermal head 19 tightly onto the paper. Have the child perform the approach motion.

FIG. 2(b) shows an example of the head control circuit 1B and the line thermal head 19, and the common pattern 3 includes heating elements 38 to 38.
51 is connected, and each of the heating elements 38 to 51 is connected to the drivers 24 to 37 through the drawer pattern 4, respectively.
The line thermal head 19 is composed of heating elements 38 to 44.
constitute a first group, and heating elements 45 to 51 constitute a second group, facing the paper 1.

The heating elements 38 to 44 and the heating elements 45 to 51 are mutually Δl with respect to the moving direction of the paper 1, that is, the direction of arrow C.
- They are arranged with a P/N shift.

Data read out by the readout circuit 17 through raster scanning is inputted via the terminal. That is, the line thermal head 19
In order to supply current to the heating elements 38 to 51 of
Drivers 24 to 37 provided corresponding to drivers 8 to 51, respectively.
A signal instructing on/off is given to the switch.

This means that when a bit on the bitmap memory 16 is "1'", the readout circuit 17 causes a driver to supply current to a heating element that prints a dot corresponding to the "l" bit for a predetermined period of time. A driver that supplies current from the reading circuit 17 to a heating element that prints a dot corresponding to the "0" bit when a signal to turn it on is sent and a bit on the bit map memory 16 is "0". A signal is sent to keep the switch off.

Therefore, the drivers 24 to 30 are the bitmap memory 1
Corresponding to the data on one line of 6, only those necessary to form dots are turned on, and current is supplied via power supply 7 to the heating element corresponding to the driver turned on.

Data similar to the above sent to the delay circuit 8 is transmitted to the drivers 24 to 3 corresponding to the heating elements 38 to 44 forming the first group.
0, the delay circuit 8 gives a delay time determined in accordance with the displacement amount P/N of the heating elements 45 to 51 and 38 to 44 and the paper feeding speed, and in the drivers 31 to 37, Corresponding to the data on one line of the bitmap memory 16, only those necessary to form dots are turned on, and current is supplied via the power supply 7 to the heating element corresponding to the driver turned on.

For example, when printing a straight line for one line, the drivers 24 to 30 are turned on at the same time, causing the heating elements 38 to 44 to generate heat at the same time, thereby forming dots on the paper 1. At the same time, the signal to turn on the drivers 31 to 37 sent to the delay circuit 8 is delayed by the delay circuit 8, and
~37 is turned on, paper 1 is turned on during that delay time.
When the paper is fed a distance of /N, current is supplied to the heating elements 45 to 51.

Therefore, since the heating elements 45 to 51 form dot rows on the same line as the dot rows formed on the paper 1 by the heating elements 38 to 44, it is possible to print straight lines without steps.

FIG. 3 is a diagram illustrating another embodiment of the line thermal head.

Common pattern 3 includes heating elements 52 and 54 with different heating parts.
is provided. That is, for example, a cut is made in a part of the heating element 52, and the resistance of the cut portion 53 is increased to cause the cut portion 53 to mainly generate heat.

Furthermore, if the cut portion 55 of the heating element 54 is shifted from the cut portion 53 of the heating element 52 by Δf=P/N, the same result as in the case of FIG. 2(b) can be obtained.

In this example, the resistance is increased by the incision, but the material may be changed and the material is not limited to this example.

〔Effect of the invention〕

As explained above, the present invention is aimed at preventing the occurrence of printing unevenness and printing of straight lines with steps in a thermal transfer printing device that prints using a line thermal head, so that high-quality printing can be achieved. It is possible to

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the present invention in detail, FIG. 2 is a block diagram explaining one embodiment of the present invention, and FIG.
4 is a block diagram illustrating an example of the prior art, and FIG. 5 is a diagram illustrating problems of the prior art. In the figure, 1 is paper, 2.38 to 52.54 are heating elements,
3 is a common pattern, 4 is a drawer pattern, 5 is a dot, 6, 24 to 37 are drivers, 7 is a power supply, 8 is a delay circuit, 9 is a heating position, 1
1 is a processor, 12 is a ROM, 13 is an R
A.M. 14 is an interface circuit, 15 is a drawing circuit, 16 is a bitmap memory, 1
7 is a readout circuit, 18 is a head control circuit, 19 is a line thermal head, 20 is a line feed control circuit, 21 is a line feed motor, 22 is an approach/escape control circuit, 23 is a motor,
53.55 is the notch. (1φ-1110 beak) (-1111

Claims (1)

[Claims] A plurality of heating elements are arranged in a direction perpendicular to the paper feeding direction so that the distance between adjacent heating elements is P, and each heating element generates heat by being supplied with energy. A line thermal head that prints one line of dots on paper is used to feed the paper continuously so that the distance to the next printed line is P, thereby printing characters, figures, etc. A thermal transfer printing device for printing, wherein the plurality of heat generating elements of the line thermal head are divided into N groups, and the heat generating portion (9) of the heat generating element of each group is set at P with respect to the paper feeding direction. /N, and print one line of dots for each of the N groups in accordance with the amount of deviation P/N in the placement of the heat generating parts (9) and the paper feed speed. A thermal transfer printing device characterized in that the timing of supplying energy is shifted.