JPH051666B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field The present invention relates to a method for color printing using a thermal head and a transfer ribbon, and particularly to a method for color printing using a thermal head and a transfer ribbon. This invention relates to a method of correcting the amount of deviation.

(b) Summary of the Invention This invention applies a constant voltage to a heating resistor when starting thermal transfer to one ink layer, and changes the resistance value of the heating resistor at least near the side edge of the recording paper at that time. The position of the recording paper side end is determined from the magnitude of the resistance value, and the drive control of the heating resistor is performed.

(c) Prior art and its drawbacks In the color printing method using a thermal head,
A recording paper is stacked on a transfer ribbon on which a plurality of ink layers of different colors are formed, and after thermal transfer for one ink layer is completed, the recording paper is returned to its original position to perform thermal transfer for the next ink layer. The ink layer usually has Y (yellow), M (magenta), and C (cyan) colors.
Three colors or four colors plus B (black) are used, and these ink layers are sequentially applied to a transfer ribbon as a set and wound up one after another by a roller. When thermal transfer for one ink layer is completed, the recording paper is returned to its original position by being pulled back in the opposite direction. That is, the positional relationship is such that the recording paper that has been thermally transferred by the ink layer of the previous color is thermally transferred by the ink layer of the next color. This operation is repeated for all color ink layers to obtain color printing on the recording paper.

However, in this method, the recording paper must be moved back and forth multiple times. Generally, this reciprocating motion is performed using rollers, etc., but during this reciprocating motion, the recording paper may shift in the lateral direction, that is, in the direction parallel to the heating resistor. There was an inconvenience that the ink caused dot positions to shift and the quality of the printed image deteriorated.

(d) Purpose of the Invention The purpose of the present invention is to detect the amount of deviation of the recording paper from the reference position by determining the position of the side edge of the recording paper when starting thermal transfer for one ink layer. , by setting the amount of deviation as the amount of correction shift of the heating resistor to be driven,
An object of the present invention is to provide a color printing method using a thermal head that can perform accurate positioning.

(e) Configuration of the Invention FIG. 2 is a schematic configuration diagram of the main parts of a color printer that implements the color printing method according to the present invention.
A thermal head 2 is arranged so that a heat generating resistor faces a rubber roller 1 which is driven and controlled in either a clockwise or counterclockwise direction, and a recording paper 3 is placed between the thermal head 2
And the transfer ribbon 4 is conveyed. The recording paper 3 can be conveyed upward or downward by the roller 1. As shown in FIG. 3, ink layers of Y, M, and C colors are sequentially formed on the base of the transfer ribbon 4, and are wound upward by rollers 5 and 6. Heat generating resistor of thermal head 2 (not shown)
The recording paper 3 and the transfer ribbon 4 are superimposed on each other at positions facing the rubber roller 1.

FIG. 4 shows the positional relationship between the heating resistor of the thermal head and the recording paper. 20 is a heating resistor which constitutes several hundred to several thousand heating dots. Point A in the figure is the right side coal end of the recording paper 3 and the heating resistor 20.
This is the intersection of the two.

FIG. 1 is a diagram explaining the principle of this invention,
Figure A is a schematic enlarged view of section A in Figure 4 above, figure B shows the resistance value of the heating resistor around section A, and figure C shows the resistance value of the heating resistor in the vicinity of section A, and figure C shows the resistance value of the heating resistor in the vicinity of section A. FIG. 4 is a diagram showing temperature changes, that is, resistance value changes, when the two contacts are in contact with each other and when they are not in contact with each other. The N heating resistors are driven and controlled by a shift register driver SRD. The shift register driver SRD receives print data from a control section (not shown) and shifts it by a predetermined number of bits using a clock pulse. The heat generating resistors R1 to RN are respectively connected to respective terminals of the parallel output stage of the shift register driver SRD, and current is supplied to the heat generating resistors corresponding to print data "1". Assume now that the right end of the recording paper 3 is located at the heating resistor R3 as shown in FIG. 1A. If all heating resistors R1 to R6 are driven in this state, R
Since heat is absorbed by the recording paper 3 in each of the heat generating resistors 4 to R6, the temperature thereof is lower than that of the heat generating resistors R1 and R2. That is, the resistance value decreases. The heating resistor R3 has a resistance value intermediate between these values. Figure 1C
shows the pulse applied to each heating resistor and the change in resistance value when the pulse is applied.
The heating resistors R1 and R2 show the change in a in the figure,
Each heating resistor R4 to R6 shows a change in b. Therefore, the maximum resistance values of R1 and R2 ΔR1 and R
The position of the side edge of the recording paper is determined by determining the maximum value ΔR2 of the resistance values of 4 to R6, that is, by examining the change in resistance value when the recording paper contacts and when it does not contact. can do.
Therefore, by determining this position, even if the recording paper 3 deviates to the left or right when it is pulled back to its original position to carry out thermal transfer to the next ink layer, the amount of deviation from the reference position can be known. By controlling the amount of deviation in the control section as a correction amount in the shift register driver SRD, it is possible to completely eliminate dot deviation when changing the ink layer.

(f) Effect of the Invention According to this invention, the position of the side edge of the recording paper is determined by utilizing the fact that the resistance value changes when the heating resistor is in contact with the recording paper and when it is not in contact with the recording paper. However, since the drive control of the heating resistor is performed using the amount of deviation of that position from the reference position as a correction value, when the recording paper is pulled back to its original position when changing the ink layer, the recording paper will shift left and right. However, thermal transfer control can be performed to maintain the same positional relationship as in the previous transfer to the ink layer, and color shift can be completely eliminated. In addition, changes in resistance can be detected electrically, and there is no need to move the recording paper or the print head itself to perform drive control using the amount of deviation as a correction shift amount, making the entire device smaller and more reliable. It has the advantage of increasing sex.

(g) Embodiment <Description of Configuration> FIG. 5 is a schematic block diagram of a color printer that implements the color printing method according to the present invention. Shift register driver SRD is a shift register,
Including latch circuit and driver, heating resistor R1
~RN is divided into multiple groups in advance and drive control is performed for each block. Print data from control unit CONT,
Clock pulses, latch pulses, and strobe pulses are respectively supplied to terminals D.IN, CP, LA, and STRn of shift register driver SRD. The clock pulse shifts the print data input from the control section to the data input terminal D.IN of the shift register driver SRD and sets it in the shift register. The latch pulse causes the latch circuit to latch the data set in the shift register. The strobe pulse serves as a synchronization signal for driving and controlling the heat generating resistors divided into a plurality of blocks in advance for each block.

The constant current source I ₀ and the constant voltage source P ₀ are each connected in parallel to the heating resistor Ri, and the constant current source I ₀ or the constant voltage source E ₀ is selected by the switch SW. The constant voltage source E ₀ is selected in the print mode, and the constant current source I ₀ is selected in the position determination mode for determining the position of the recording paper side edge. When the constant current source _I0 is selected, the AD converter A/D converts both single voltages of the heating resistor Ri into AD converters and outputs the AD converter to the control unit CONT. As will be described later, in the position determination mode, the heating resistors are switched one by one from R1 to Rn, and the amount of electricity corresponding to the resistance value of each heating resistor is checked. At this time, the AD conversion switch A/D converts the voltage across each end of each anti-fever antibody to the control unit.
It will be output to CONT.

<Description of Operation> FIGS. 6 and 7 are flowcharts showing the operation of the control section of the color printer.

First, at step n1 (hereinafter step ni is simply referred to as ni), print data is input from the control unit CONT to the input terminal D.IN of the shift register driver SRD, and the print data is shifted into the shift register driver SRD by a clock pulse. Register is set. Next, a latch pulse is supplied at n2, and the data set in the shift register is latched into the latch circuit. At this time, the recording paper is at the reference position. In n3, strobe pulse is SR1
The heating resistors for one row are sequentially driven block by block. Since the ink layer of the transfer ribbon 4 is initially of Y color, the recording paper 3 is fed line by line at n5 and steps n1 to n3 are repeated until the Y color is completed. When the Y color transfer is completed, the recording paper 3 is sent in the opposite direction and returned to its original position at n6. next
At n7, the mode is switched to the above-mentioned position determination mode, and when pulled back at n6, the positions of both ends of the recording paper are determined. As will be described later, in this both end position determination operation, the amount of deviation of the recording paper from the reference position is determined as the corrected shift amount. Subsequently, at n8, the same printing control as above n1 to n5 is performed, and the transfer for M color is completed. Next, at n9, the recording paper 3 is pulled back and returned to its original position in the same manner as at n6 above, and at n10, the positions of both ends are determined in the same manner as at n7 above. Furthermore, n11 to n5 above
The following operations are performed to transfer the C color. By the above-described operation, thermal transfer to the ink layers of each color of YMC is completed for the length of each ink layer.

FIG. 7 is a detailed flowchart of the operation for determining the positions of both ends checked in steps n7 and n101.

In n20, counter i is initialized to 1, and in n21,
Ri on data shift register driver SRD
send to At n22, a latch pulse is sent to the shift register driver SRD to latch the data in the shift register. Next, a strobe pulse is sent at n23 to supply a low current to the heating resistor Ri. next
The AD converter A/D is operated to AD convert the terminal voltage of Ri at that time, and the data Di is stored in the memory M at n25. These operations are repeated until i>N at n26 and n27, and when i>N, the process proceeds to n28. In this n28, memory M (M1~
Based on the data stored in MN), that is, the magnitude of the voltage across each heating resistor Ri to RN, the heating resistor at which both ends of the recording paper 3 are located is determined as shown in FIG. That is, the positions of both ends of the recording paper are determined, and the amount of deviation of that position from the reference position is determined as the corrected shift amount. By adding this correction shift amount to the previous print data shift amount as a correction amount when inputting print data when performing thermal transfer for the current ink layer, thermal transfer for the current ink layer can be performed without causing color shift. can.

In this embodiment, in the position determination mode, the constant current source _I0 supplies a constant current to each heating resistor, but the constant voltage source in the color printing mode
E ₀ may be used as is and the current may be detected in the position determination mode. In addition, as shown in Fig. 7, in the position determination mode, the amount of electricity corresponding to the resistance value of each heating resistor is determined for each heating resistor, and this amount of electricity is detected near both ends of the recording paper. The process may be performed only for heating resistors that exist in the area. Furthermore, once the position of one side edge of the recording paper is determined, the position of the other side edge can also be determined. Therefore, the above-mentioned amount of electricity is detected by detecting the heating resistor located near the left or right edge of the recording paper. It is also possible to perform only

[Brief explanation of the drawing]

FIGS. 1A to 1C are diagrams illustrating the principle of the color printing method according to the present invention. FIG. 2 is a schematic diagram of the main parts of a color printer that implements the color printing method of the present invention, FIG. 3 is a diagram of the configuration of a transfer ribbon used in the color printer, and FIG. 4 is a diagram of the arrangement of recording paper and a thermal head. FIG. 5 is a block diagram of an example of a color printer that implements the method of the present invention, and FIGS. 6 and 7 are flowcharts showing the operation of the color printer. 2...Thermal head, 20 (R1~RN)...
...heating resistor.

Claims (1)

[Claims] 1. Recording paper is stacked on a transfer ribbon on which a plurality of ink layers of different colors are formed, and after thermal transfer for one ink layer is completed, the recording paper is returned to its original position to perform thermal transfer for the next ink layer. In a color printing method using a thermal head, when thermal transfer is started for one ink layer, a voltage is applied to the heating resistors located at least near the side edges of the recording paper, and the voltage of each heating resistor at that time is determined. The feature is that the amount of electricity corresponding to the resistance value is measured, the position of the edge of the recording paper is measured from the magnitude, and the drive control of the heating resistor is performed using the amount of deviation of that position from the reference position as a correction shift amount. A color printing method using a thermal head.