JPS602384A - Controlling system for thermal printing - Google Patents

Abstract

PURPOSE:To print while constantly maintaining the heating temperature of a printing head at a substantially fixed value and enable to make uniform printed density, by compensating for the variation of the heating condition of the printing head generated with the progress of printing from the start of printing. CONSTITUTION:When a printing timing PT is inputted into a register 14 and a timing-generating circuit 16, predetermined printing data PD are printed in dots by the printing head 22 in a heating condition according to a heating pulse signal HT. The printing data PD are converted into heating data HD1, HD2 by weighting circuits 10a, 10b, printing progress data ND based on the printing data PD stored in the register 14 are added to the heating data by an adding circuit 11, data according to the amount of heat accumulated in the head 22 are stored into the register 14 through a multiplexer 15, and the pulse width of the signal HT is reduced in accordance with the heat accumulation. When the printing data PD are a space (blank), the pulse width is increased through a subtaracting circuit 13. Accordingly, the printed density can be made to be uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thermal printing control system used, for example, in thermal printing or thermal transfer printing.

[Technical background of the invention and its problems]

Generally, in thermal printers and thermal transfer printers (serial dot matrix type printers, etc.), one heat-generating print head (hereinafter simply referred to as print head) scans the printing paper in the row direction.
The line is printed. Heat-sensitive dots like this/
In this case, a heat generation timing pulse signal synchronized with the normal print timing signal is sent to the print head. The print head generates heat for a period according to this heat generation timing pulse signal,
It is configured to print dots on plain paper via thermal paper or thermo-separable ink ribbon.

By the way, in the above-mentioned printer, in the printing operation for one line of paper, the heat generation state of the print head differs between, for example, the start of printing and the vicinity of the end of printing due to the heat storage effect. Therefore, in the printing result for one line of paper, there are parts where the printing density differs depending on the printing progress in that one line, and there is a drawback that the printing quality as a whole deteriorates. In order to solve this problem, conventional methods have been proposed to control the heat generation state of the print head. However, in the conventional method, control is performed primarily based on the printing position, etc., and therefore it is not possible to control the heat generation state of the print head based on actual changes in heat.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to prevent the occurrence of parts with different print densities in the print result due to the printing process from the start of printing, and to improve the print quality of the print result. An object of the present invention is to provide a thermal printing control method that can increase the negative as a whole.

[Summary of the invention]

In the present invention, a thermal dot printer or the like is provided with a register that stores printing progress data from a predetermined printing start time to a current printing time in response to a print timing signal. The printing progress data output from this register is input to an arithmetic circuit that performs addition and subtraction and a timing generation circuit.

The arithmetic circuit adds or subtracts heat generation data set based on the degree of heat storage of the heat generating print head based on the number of printed dots of the print data immediately before the current printing time to the printing progress data, and uses the calculation result as a new printing progress. Output to register as data. The timing generation circuit supplies a heat generation timing pulse signal having a pulse width based on printing progress data to the heat generation print head in synchronization with the print timing signal. With this configuration, the heat generation state of the heat-generating print head is adjusted according to the progress of printing from the start of printing, and the print density of the print result can be made uniform.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a print control circuit according to an embodiment. In Figure 1, % ZOa, lOb
The first and second weight circuits respectively generate heat generation data HDt and HDz according to print data PD input from a computer (not shown). That is, the first advantage is that the circuit 10a is used to print the print head (i.e., print data Pi) when performing a print operation according to the print data Pi).

Heat generation data 1 based on the degree of heat storage of the heat generating print head)
(l) The second weighting circuit 10b outputs Z to the addition circuit 11. The second weighting circuit 10b outputs the heat generation data H1)2 corresponding to the print data PI) inverted by the inverter 12 to the subtraction circuit 13.
Output to. In this case, the heat generation data H1)2 is data based on the heat storage of the print head that has decreased due to heat radiation.

The first and second weighting circuits 10a, 10', and b are each a circuit as shown in FIG. 2, for example. In this case, the addition side f@tt and the subtraction circuit 13 each have 4 bits, and 1Y=A+BJ and "Y
=B-AJ calculations will be performed respectively.

The adder circuit 11 adds the heat generation data HDZ from the first weighting circuit 10a to the print progress data ND output from the register 14 and outputs the result to the multiplexer 15.

Further, the subtraction circuit 13 subtracts the heat generation data )LL)2 from the printing progress data ND of the register 14 and outputs the result to the multiplexer 15. Based on the input print data PD, the multiplexer 15 selects the output data of the adder circuit 11 and outputs it to the register 14 if the print data (Pi) is data consisting of a predetermined number of dots. Also,
When the print data FD is a space (golden white), the multiplexer 15 selects the output data of the reduction 1 circuit 13 and outputs it to the register 14. The register 14 stores the data output from the multiplexer 15 in response to the print timing signal PT as printing progress data NL)1. The timing generation circuit I6 includes a register 14, etc.
A heating timing pulse signal (hereinafter referred to as a heating pulse signal) HT having a pulse width that changes according to the printing progress data NJJ outputted from the printer, that is, data based on the number of printed dots from the time of printing start to the present time, is used as the printing timing signal. Supplied to the print head in synchronization with FT.

The operation of a thermal printer using a printing control circuit with such a configuration will be explained. Let us now assume that a sheet of paper 2 as shown in FIG.
It is assumed that in 21 of a predetermined line of 0, the print head 22 moves from the left end to the right end to perform printing. First, the print timing signal FT as shown in FIG.
4 and the timing generating circuit 16, the heating pulse signal HT is sent from the timing generating circuit 16 to the print head 22. In this case, the left end of 21 in one line is the print start position, and the print head 22 prints the predetermined print data PL) in dots in a heat generation state corresponding to the heat generation pulse signal HT. At this time, at the time of starting printing, the printing progress data Nu) is not stored in the register 14, and the timing generation circuit 16 outputs a heating pulse signal HT having a pulse width WO as shown in FIG. 3, for example. Furthermore, when the print head 22 moves to the right (in the direction of the arrow in FIG. 3) to perform the next print, the register 14 stores printing progress data NL based on the previous print data PD.
) is memorized. That is, the print data P immediately before the current printing time
The first and second weighting circuits 10a,
lOb Each heat generation data 1-11Jz, HD2 is output 0 Each heat generation data 1(L)z, ML)2 is a printing operation according to the print data PD (i.e., the number of printed dots) as described above. This data is based on the degree of heat accumulation that occurs in the print head. In the adder circuit 11, printing progress data ND (no data is stored at this point) in the register 14 is added to the heat generation data HDt, and the result is output to the multiplexer 15.

Further, the subtraction circuit 13 subtracts the heat generation data HDJ from the printing progress data ND.

The calculation result is not relevant at this point. Since the print data PD is data consisting of a predetermined number of dots, the multiplexer 15 selects the output data of the adder circuit 11 and outputs it to the register 14.As a result, the register 14 has the adder circuit 11 as described above. output data, that is, data corresponding to the amount of heat stored in the print head corresponding to the number of dots in the print data PD is stored. Therefore, from timing generation (b) @Z6, the heating pulse signal HT with the pulse width W7, which has changed from the previous pulse width W17j according to the printing progress data ND of the register 14, is printed in synchronization with the print timing signal PT. Also, when the print head 22 prints the next line IL, if the previous print data PD is a space (margin), the output data of the subtraction circuit 13 is stored in the register. That is, the subtraction circuit 13 uses the printing progress data ND in the register 14.
The heat generation data HDz is subtracted from , and the calculation result is output to the multiplexer 15 . The multiplexer 15 is
Since the print data PI) is a space, the subtraction port fI1
113 is selected and output to the register 14. As a result, the register 14 stores the output data of the subtraction circuit 13, that is, data corresponding to the amount of heat stored in the print head when the amount of heat stored in the print head decreases due to heat radiation due to the space for the print data PD. Therefore, the timing generation circuit 16
From then on, as shown in FIG. 4, a heating pulse signal HT having a pulse width W2 changed from the previous pulse width νVo is supplied to the print head 22 in synchronization with the print timing signal PT.

In this way, when the print head 22 prints on a predetermined row 21 of the paper 20, the pulse width of the heating pulse signal HT decreases as shown in FIG. change as it does. This is because, as described above, the printing progress data NIJ is increased and stored in the register 14 in accordance with the number of printed dots every time printing is performed, and the timing generation circuit 16 is generated based on this printing progress data ND.
This is also because the pulse width of the output heating pulse signal HT changes to decrease. Therefore, by reducing the pulse width of the heat generation pulse signal H'r, a situation in which heat is accumulated and the heat generation temperature increases each time the print head 22 prints can be prevented. That is, when the print head 22 continuously performs printing operations, the heat generation energy of the print head 22 can be reduced in accordance with the amount of heat stored by changing the pulse width of the heat generation pulse signal HT. Thereby, in the printing operation for one line 21 of the paper 20, the heat generation state of the print head 22 can be made almost uniform regardless of the printing position, and the print density of the printing result can be made constant. Further, when the print head 22 performs a printing operation, if a space (margin) is provided instead of the print data PD consisting of a predetermined number of print dots, the output data of the subtraction circuit 13 is stored in the register 14. Therefore, as described above, the heating pulse signal HT
Since the pulse width increases, it is possible to prevent the temperature of the print head 22 from decreasing due to the space. That is, especially when the print head 22 operates so as to provide a continuous space, the heat generation energy of the print head 22 can be increased in accordance with the amount of heat storage that decreases due to heat radiation. This allows the print head 2 to not print.
Even if the print head 220 radiates heat and the heat storage decreases, the heat generation state of the print head 220 can be made uniform as a whole.

In the above embodiment, the printing control circuit shown in FIG. 1 may be constructed by so-called firmware using a microcomputer. In this case, the entire circuit can be miniaturized and the overall cost of the thermal printer can be reduced.Furthermore, the weighting circuits 10a and 10b shown in Figure A1 are each ROM (read only memory). Consists of etc.
A circuit that stores heat generation data in a table in advance may be used. In this case, applications such as being able to detect the ambient temperature of the print head and change the value to be added or subtracted (corresponding to A in FIG. 2) based on that value are possible.

[Effects of the Invention] As detailed above, according to the present invention, in a thermal printer or the like, changes in the heat generation state of the print head caused by printing from the time of printing start are corrected, and the heat generation temperature of the print head is always maintained. The dragon can perform printing operations almost constantly. Therefore, the print density of the print result can be made uniform regardless of the print position on the paper. As a result, printing quality can be improved as a whole. Furthermore, when the print head performs continuous printing operations, the heat generation energy of the print head can be reduced, so the heat dissipation time of the print head can be shortened. Therefore, by reducing the operation time of the print head based on the heat generation pulse signal, it is possible to obtain the effect that the printing speed can be reduced as a result.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a print control circuit according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing the specific configuration of the circuit for each weighting shown in FIG. 1, and FIG. 3 is a print head FIGS. 4 and 5 are timing charts relating to the operation of the print control circuit shown in FIG. 1. FIGS. roa, 1ob...Electrical circuit, 11...Addition circuit%13...Subtraction circuit, 14...Register, 16.
...Timing generation circuit.

Claims (1)

[Claims] a register that stores printing progress data from a predetermined printing start point to a current printing point in accordance with a print timing signal;
In response to the input of the print data immediately before the current printing time, the heat generation data set according to the degree of heat storage of the heat generation print head based on the number of print dots of the print data is added to the print progress data output from the above register. calculation means for outputting the subtracted calculation result to the register as new printing progress data; and a heating timing pulse signal having a pulse width based on the printing progress data output from the register in synchronization with the printing timing signal. A thermal printing control method characterized by comprising a timing generating means for supplying a heat-generating print head.