JP2763842B2 - Paper transport control method for thermal printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper transport control method for a thermal printer capable of automatically adjusting a color shift caused by uneven paper transport due to aging, environmental changes, and the like.

[0002]

2. Description of the Related Art The structure of a thermal printer used for implementing a conventional paper transport control method will be described with reference to FIGS. FIG. 3 and FIG. 4 are a block diagram and a side view showing a printer used for implementing a conventional paper transport control method.

In FIG. 3, a thermal printer used for implementing a conventional paper transport control method includes an MPU (microprocessor) 1 for controlling paper transport, a ROM 2 for storing program data, and the like. A RAM 3 for temporarily storing data and the like, an input buffer 4 for inputting data, a printing control circuit 5 including a dot counter and the like, an output buffer 6 for outputting data to the head, and a bus 11 connected to the MPU 1 Ink motor drive circuit 7
And an ink motor 8 connected to an ink motor drive circuit 7 for conveying an ink sheet;
, And a platen motor 10 connected to the platen motor drive circuit 9 and driving a platen via a belt.

[0004] In FIG. 4, the above-described thermal printer passes an ink sheet 13 through a lower side of a head 12.
Roller 14 and take-up roller 15 for transporting
And a mechanism such as a platen 16 for transporting the paper 21 sandwiched between the clampers 20, a pinch roller 17, rollers 18, 19, and an optical sensor 22 for detecting the clamper 20 (the leading end of the paper 21).

Next, a paper transport control method of the above-described conventional thermal printer will be described with reference to FIG. FIG.
6 is a timing chart showing the operation of a conventional paper transport control method for a thermal printer.

In FIG. 5, (a) shows the degree of printing, and the hatched portion represents the portion of printing. (B) shows the uncorrected paper transport amount, and (c) shows the transport amount correction amount. (D) is a state in which the transport amount is corrected ((b) + (c))
Represents Arrows A represent changes such as aging and environmental changes, and the one-dot chain lines and dotted lines in (b) and (d) represent the second color and third color prints, respectively. Note that the horizontal axis is the printing progress direction.

First, a correction amount for canceling the color misregistration caused by the unevenness of the paper conveyance is obtained in advance by an experiment or the like and stored in the RAM 3. Then, when actual printing is performed, the MPU 1
The correction amount, which is a constant value for canceling the color shift stored in M3, is read out, and the paper transport amount is corrected as shown in FIG.

[0008]

In the above-described conventional paper transport control method for a thermal printer, since the correction amount of the paper transport amount is a constant value, as shown by an arrow A in FIG. It is not possible to cope with a change in frictional resistance of each part due to the above-mentioned factors, and there is a problem that color shift occurs due to aging or the like.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a paper transport control method for a thermal printer which can correct a color shift due to aging, environmental change, and the like. .

[0010]

A paper transport control method for a thermal printer according to the present invention includes the following steps. [1] A first counting step of counting the first number of drive pulses required to feed the sheet to the home position by the platen after printing the first color in the simulation mode. [2] A second counting step of counting a second driving pulse number required for feeding the sheet to the home position by the platen after printing the second color in the simulation mode. [3] A first calculation step for obtaining a first difference between the first drive pulse number and the second drive pulse number. [4] A third counting step of counting the number of third drive pulses required to feed the sheet to the home position by the platen after printing the third color in the simulation mode. [5] A second calculation step for obtaining a second difference between the first drive pulse number and the third drive pulse number. [6] When printing the second color during actual printing, use the first color
A first control step of controlling paper conveyance based on the difference between the two. [7] A second control step of controlling paper conveyance based on the second difference when printing the third color during the actual printing.

[0011]

In the present invention, in the first counting step, after the first color is printed in the simulation mode, the number of first drive pulses required for feeding the sheet to the home position by the platen is counted.
In the second counting step, after the second color is printed in the simulation mode, the number of second drive pulses required to feed the sheet to the home position by the platen is counted. Further, a first difference between the first drive pulse number and the second drive pulse number is obtained by the first calculation step. After the third color is printed in the simulation mode by the third counting step, the third necessary for feeding the sheet to the home position by the platen is used.
Are counted. Further, a second difference between the first drive pulse number and the third drive pulse number is obtained by the second calculation step. Then, in the first control step, when printing the second color at the time of actual printing, paper conveyance is controlled based on the first difference. By the second control step, the third printing is performed during the actual printing.
When printing a tint, paper transport is controlled based on the second difference.

[0012]

Embodiment 1 The hardware configuration of the thermal printer used to carry out the first embodiment of the present invention is the same as that shown in FIGS.

Next, the operation of the first embodiment will be described with reference to FIGS. FIG. 1 is a flowchart showing an operation in a simulation mode according to the first embodiment of the present invention;
FIG. 2 is a timing chart showing the operation of the first embodiment of the present invention.

In FIG. 2, (a) shows the degree of printing, and the hatched portion indicates the portion of printing. (B) shows the uncorrected paper transport amount, and (c) shows the transport amount correction amount. (D) is a state in which the transport amount is corrected ((b) + (c))
Represents The alternate long and short dash line and the dotted line represent the second color and the third color, respectively. Note that the horizontal axis is the printing progress direction.

The simulation mode is activated by operating a self-printing key on the operation panel. Step 30 in FIG.
, The MPU 1 prints the first color. For example, yellow is printed. That is, the clamper 20 moves from the home position shown in FIG. 4 to the entrance of the platen 16 and the pinch roller 17 (printing end position), during which yellow is printed. Further, the number N0 of platen driving pulses during that period is counted.

In step 31, the sheet 21 is fed to the home position, and the number N1 of platen drive pulses required to feed the sheet 21 to the home position is determined. That is, the platen driving pulse N1 from the printing end position to the time when the optical sensor 22 detects the clamper 20 is counted.

In step 32, the second color is printed. For example, magenta is printed. That is, clamper 2
0 is the platen 1 from the home position shown in FIG.
6. Move to the entrance of the pinch roller 17 (printing end position), during which magenta is printed.

In step 33, the sheet 21 is fed to the home position, and the number N2 of platen drive pulses required for feeding the sheet 21 to the home position is determined. That is, the platen drive pulse N2 from the printing end position to the time when the optical sensor 22 detects the clamper 20 is counted.

In step 34, a difference ΔN21 between the transport amounts of the first and second color papers 21 corresponding to the color shift amounts of the first and second colors is obtained. ΔN21 = N2-N1

In step 35, the third color is printed. For example, cyan is printed. That is, the clamper 20
From the home position shown in FIG.
6. Move to the entrance of the pinch roller 17 (printing end position), during which cyan is printed.

In step 36, the sheet 21 is fed to the home position, and the number N3 of platen drive pulses required for feeding the sheet 21 to the home position is determined. That is, the platen drive pulse N3 from the printing end position to the time when the optical sensor 22 detects the clamper 20 is counted.

In step 37, the difference ΔN31 between the transport amounts of the first and third color papers 21 corresponding to the color shift amounts of the first and third colors is obtained. ΔN31 = N3-N1

The above-described simulation mode printing is performed periodically (for example, every six months), and the color shift correction amounts (ΔN21, ΔN31) stored in the RAM 3 are updated. Then, when actual printing is performed, the MPU 1 corrects the transport amount based on the latest color shift correction amount as shown in FIG. That is, when printing the second color, when the printing length is short, the platen 16 is transported and driven at N0 + ΔN21. 3
Similarly, when the printing length is short, the platen 16 is transported and driven at N0 + ΔN31. The determination of the print length is based on comparison of N1, N2, and N3.

The first embodiment of the present invention, as described above,
Performs color misregistration simulation printing, detects the difference in the amount of paper movement for each color printing, and calculates the color misregistration correction amount inside the printer, so that color misregistration is automatically performed with high accuracy and without manual adjustment. The purpose is to adjust.

Conventionally, color misregistration correction has been performed with a fixed amount of correction. However, since the frictional resistance of each part changes due to aging, environmental changes, etc., color misregistration due to aging or the like occurs. Was.

Therefore, a color misregistration simulation mode is provided in the printer, and the optimal correction amount is automatically calculated inside the printer and automatically set by periodic simulation printing operation, thereby performing color misregistration correction corresponding to aging and the like. Run.

At the time of printing, the paper 21 is conveyed by the rotation of the platen 16, but a slight slippage occurs between the platen 16 and the paper 21 due to friction between the printing screen of the paper 21 and the pinch roller 17. Since the slip amount is different in the printing of each color, a color shift occurs. At the time of printing of each color, the amount of platen drive pulses required to make the paper 21 make one revolution along the belt is measured, the deviation between the colors is detected, and the correction amount is calculated.

Therefore, the color misregistration can be adjusted with high precision and automatically. Further, there is an effect that the color shift can be adjusted with a simple operation even with respect to aging, environmental change, and the like.

[0029]

According to the present invention, as described above, after printing the first color in the simulation mode, the first count for counting the first drive pulse number required to feed the paper to the home position by the platen is provided. And a second counting step of counting a second driving pulse number required for feeding the sheet to the home position by the platen after printing the second color in the simulation mode; and A first calculation step for obtaining a first difference between the number of driving pulses and the second number of driving pulses, and a step of printing the third color in the simulation mode and then feeding the sheet to the home position by the platen. A third counting step of counting the number of required third drive pulses, and the first drive pulse And a second of said third number of drive pulses
And a first control step of controlling paper transport based on the first difference when printing the second color at the time of actual printing, and a third control step of controlling the third color at the time of actual printing. Since the printing includes the second control step of controlling the paper conveyance based on the second difference, it is possible to correct color shift due to aging or the like.

[Brief description of the drawings]

FIG. 1 is a flowchart showing the operation of Embodiment 1 of the present invention.

FIG. 2 is a timing chart showing the operation of the first embodiment of the present invention.

FIG. 3 is a block diagram showing a printer used for implementing a conventional paper conveyance control method.

FIG. 4 is a diagram illustrating a side view of a printer used for implementing a conventional paper conveyance control method.

FIG. 5 is a timing chart showing the operation of a conventional paper transport control method for a thermal printer.

[Explanation of symbols]

 1 MPU 2 ROM 3 RAM 9 Platen motor drive circuit 10 Platen motor 16 Platen 20 Clamper 21 Paper 22 Optical sensor

Claims (1)

(57) [Claims] A first counting step of counting a first driving pulse number required for feeding a sheet to a home position by a platen after printing a first color in a simulation mode, and a second color in the simulation mode. After printing, a second counting step of counting a second driving pulse number required to feed the sheet to the home position by the platen, the first driving pulse number and the second driving pulse number First
A first calculation step for calculating the difference between the first and second colors, and a third count for counting a third drive pulse number required to feed the sheet to the home position by the platen after printing the third color in the simulation mode. A second calculating step for obtaining a second difference between the first driving pulse number and the third driving pulse number, and a paper based on the first difference when printing a second color during actual printing. A thermal printer, comprising: a first control step of controlling conveyance, and a second control step of controlling paper conveyance based on the second difference when a third color is printed during the actual printing. Paper transport control method.