JP3673264B2 - Thermal head control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention controls a thermal head that includes a resistive element electronic component, and performs energization control of a necessary amount of power on the resistive element electronic component in a preset time to use a plurality of printing elements that print one dot. The present invention relates to a thermal head control device.
[0002]
[Prior art]
A print head using a plurality of printing elements using resistors, for example, a line thermal head in which a plurality of heating elements are arranged in a row, energizes the ink element of the ink ribbon when printing using the ink ribbon. It is melted by the generated heat and transferred to the paper.
[0003]
There is a thermal head control method described in Japanese Patent Application No. 8-344174 as a thermal head control method for a recording apparatus provided with such a thermal head.
[0004]
Here, this thermal head control method will be briefly described with reference to FIGS. FIG. 5 is a block diagram including a partial circuit diagram showing a schematic configuration of a head controller 2 as a print head control apparatus to which the present invention is applied and a line thermal head 1 controlled by the head controller 2. A thermal printer using this line thermal head uses an ink ribbon of resin-based ink.
[0005]
The head controller 2 controls the line thermal head 1 and is connected to be controlled by a printer main body control unit 3 that controls the entire thermal printer, and print data is developed (drawn) into dot data. It is connected to the data memory 4 so that print data can be read.
[0006]
Although not shown, the printer main body control unit 3 controls peripheral devices via various controllers and interfaces, conveys paper, and prints desired print data on the paper by the line thermal head 1. It comes to discharge.
[0007]
The line thermal head is configured by arranging 1280 heating resistors 1-1 to 1-1280 as printing elements in a line. One end of each of these heating resistors 1-1 to 1-1280 is connected to the drive power source Vcc via the common resistor 5.
[0008]
The other ends of the heating resistors 1-1 to 1-1280 are respectively connected to collector terminals of NPN transistors 6-1 to 6-1280, and the emitters of all these transistors 6-1 to 6-1280. Both terminals are connected to the ground (0 [V]).
[0009]
The base terminals of the transistors 6-1 to 6-1280 are connected to the output terminals of the AND circuits 7-1 to 7-1280, respectively. An enable signal output from the head controller 2 is input to one input terminal of each of the AND circuits 7-1 to 7-1280, and the AND circuits 7-1 to 7-1 The other input terminal 7-1280 is connected to each channel output terminal (No. 1 to No. 1280) of the latch circuit 8.
[0010]
Each channel input terminal of the latch circuit 8 is connected to each data output terminal (No. 1 to No. 1280) of the shift register 9 and is latched by a latch signal (strobe signal) input from the head controller 2. The circuit 8 latches the data output from each data output terminal of the shift register 9 and outputs it from each channel output terminal.
[0011]
The shift register 9 sequentially shifts the serial print data (1 line = 1280 bits) supplied from the head controller 2 and outputs it from each data output terminal as described above.
[0012]
FIG. 6 is a block diagram showing a schematic configuration of the head controller 2. The head controller 2 includes a head control unit 11, a data control unit 12, an enable signal output unit 13, a counter unit 14, a temperature holding period selection unit 15, a 60% pulse generation unit 16, and a 40% pulse generation. The unit 17 and the temperature rise timer 18 are configured.
[0013]
The enable signal output unit 13, the 60% pulse generation unit 16 or the 40% pulse generation unit 17, and the temperature rise timer 18 constitute an energization control means. Further, the counter unit 14 and the temperature holding period selection unit 15 constitute an intermittent energization adjusting means.
[0014]
The head control unit 11 is connected to the printer main body control unit 3, and based on a control signal or control data from the printer main body control unit 3, first, a control signal for data reading output to the data control unit 12. Output a latch signal (strobe signal) to the latch circuit 8 at the timing when one line of print data is set in the shift register 9, and then output the enable signal in accordance with the print timing on the paper. An enable signal output control signal is output to the unit 13.
[0015]
The data control unit 12 is connected to the print data memory 4 so as to be accessible on the basis of a data read output control signal. The print data memory 4 reads the print data for each line data (1280 bits). And output to the shift register 9 together with the counter unit 14.
[0016]
The counter unit 14 counts the number of dot data (1) to be printed in one line (in 1280 bits). If the number is larger than a preset number, a switching signal (low level) indicating a high printing rate is obtained. Signal) is output to the temperature holding period selection unit 15. On the other hand, the 60% pulse generation unit 16 and the 40% pulse generation unit 17 output pulse signals having a duty ratio of 60% and 40% respectively to the temperature holding period selection unit 15 in a preset period.
[0017]
When no switching signal is input from the counter unit 14, the temperature holding period selection unit 15 supplies a pulse signal having a duty ratio of 40% from the 40% pulse generation unit 17 to the enable signal output unit 13, and the counter When the switching signal from the unit 14 is input, a pulse signal having a duty ratio of 60% from the 60% pulse generating unit 16 is supplied to the enable signal output unit 13.
[0018]
The enable signal output unit 13 outputs an enable signal to the AND circuits 7-1 to 7-1280. Based on the enable signal output control signal from the head control unit 11, first, the temperature signal is output. At the same time as the rising period timer 18 is started, the enable signal is fixed at a low level. In the temperature rise timer 18, the temperature (head temperature) of the heating resistors 1-1 to 1-1280 of the line thermal head 1 is sufficiently higher than the melting point T2 of the resin-based ink and lower than the heat resistance temperature T1 of the ink ribbon. The energization time t1 required to reach the optimum head temperature for printing is set in advance, and when the counting of the energization time t1 is completed, a temperature rise period end signal is output to the enable signal output unit 13. ing. The enable signal output unit 13 outputs the pulse signal supplied from the temperature holding period selection unit 15 based on the temperature rise end signal as an enable signal for a preset transfer time t required for printing. When the transfer time t ends, the enable signal is fixed at a high level.
[0019]
In such a configuration, as shown in FIG. 7, energization control is performed on the heating resistors 1-1 to 1-1280 that perform printing.
[0020]
When the printing rate in one line is small, it is determined that the switching signal is not output from the counter unit 14 when the printing data of one line is output from the data control unit 12 to the shift register 9. The temperature holding period selection unit 15 selects a pulse signal with a duty ratio of 40% from the 40% pulse generation unit and supplies it to the enable signal output unit 13.
[0021]
Therefore, in this one-line (one dot) printing, the heating resistors 1-1 to 1-1280 that perform printing are initially energized for the energization time t1 counted by the temperature rise timer 18, and printing is performed. As shown in the graph curve S1, the head temperature of the heating resistors 1-1 to 1-1280 to be performed is a temperature that is sufficiently higher than the melting point T2 of the resin ink and lower than the heat resistance temperature T1 of the ink ribbon. Rise. When the energization time t1 elapses, the heating resistors 1-1 to 1-1280 that perform printing are intermittently energized based on a pulse signal with a duty ratio of 40% for a preset transfer time t. The head temperatures of the heating resistors 1-1 to 1-1280 for printing are maintained at a temperature within the range between the melting point T2 of the resin-based ink and the heat-resistant temperature T1 of the ink ribbon. When the transfer time t elapses, energization to the heating resistors 1-1 to 1-1280 for performing printing is stopped, and the head temperature of the heating resistors 1-1 to 1-1280 rapidly decreases.
[0022]
Further, when the printing rate in one line is large, a switching signal is output from the counter unit 14 when the printing data of one line is output from the data control unit 12 to the shift register 9. The temperature holding period selection unit 15 selects a pulse signal with a duty ratio of 60% from the 60% pulse generation unit and supplies it to the enable signal output unit 13. Therefore, in the printing of one line (one dot), the heating resistors 1-1 to 1-1280 that perform printing are initially energized for the energization time t1 counted by the temperature rise timer 18 to perform printing. As shown by the graph curve S2, the head temperature of the heating resistors 1-1 to 1-1280 rises to the optimum head temperature for printing that is sufficiently higher than the melting point T2 of the resin-based ink and lower than the heat resistance temperature T1 of the ink ribbon. To do. However, since the printing rate is large, the number of heating resistors 1-1 to 1-1280 that perform printing increases, and therefore, from the relationship with the common resistor 5, the heating resistors 1-1 to 1-1280 that perform printing. As a result, the temperature rise curve of the heating resistors 1-1 to 1-1280 becomes gentler than the case where the printing rate is small, and the temperature reached is also lowered.
[0023]
When the energization time t1 elapses, the heating resistors 1-1 to 1-1280 performing printing are intermittently energized based on a pulse signal having a duty ratio of 60% for a preset transfer time t. The head temperatures of the heating resistors 1-1 to 1-1280 for printing are maintained at a temperature within the range between the melting point T2 of the resin-based ink and the heat-resistant temperature T1 of the ink ribbon. When the transfer time t elapses, energization to the heating resistors 1-1 to 1-1280 for performing printing is stopped, and the head temperatures of the heating resistors 1-1 to 1-1280 are lowered.
[0024]
According to such a configuration, the 60% pulse generator 16 and the 40 pulse generator 17 that respectively output pulse signals having a duty ratio of 60% and a duty ratio of 40%, and printing in one line of print data (selected) The counter unit 14 that counts the number of dot data and outputs a switching signal indicating a large printing rate when the number of dots is equal to or larger than a preset number, and a duty ratio of 60% and a duty ratio of 40% based on the switching signal. The temperature holding period selection unit 15 that selects and outputs any one of the pulse signals and the head temperatures of the heating resistors 1-1 to 1-1280 are sufficiently higher than the melting point T2 of the resin-based ink, and the heat resistance of the ink ribbon A temperature rising period timer 18 for measuring the energization time t1 required to reach the optimum temperature for printing lower than the temperature T1 is provided, and the heating resistors 1-1 to 1-128 are energized. After continuous energization for t1, the energization of the heating resistors 1-1 to 1-128 is performed by intermittently energizing for a transfer time t required for printing set in advance by a pulse signal selected and output by the temperature holding period selection unit 15. The head temperature can be maintained for a transfer time t required for printing within a temperature range optimal for printing sufficiently higher than the melting point T2 of the resin-based ink and lower than the heat resistance temperature T1 of the ink ribbon.
[0025]
Further, by changing the duty ratio in intermittent energization depending on the size of the printing rate, power is appropriately adjusted with respect to fluctuations in the voltage applied to the heating resistors 1-1 to 1-1280 due to the printing rate, and the heating resistor The temperature control of the bodies 1-1 to 1-1280 can be performed.
[0026]
In the thermal head control device having such a configuration, when the amount of heat accumulated in the head is reflected in the energization power to the printing element, the temperature of the head is detected by temperature detection means such as a thermistor provided near the line thermal head. However, the energization time is determined in consideration of the information.
[0027]
[Problems to be solved by the invention]
When printing with a high printing rate (a large number of heating elements energized at the same time) continues continuously, as shown in FIG. 8, the heat storage of the head is large, and the time for exceeding the ink melting temperature T2 is lengthened and formed. Thermal energy more than necessary is printed on the dots, and the dots are formed larger and the print quality is impaired. In order to solve this problem, when a predetermined number of lines continue to have a high printing rate in one line, the low power energization mode A is set to reduce the amount of heat generated.
[0028]
On the other hand, when the printing rate in one line is small, the low power energization mode B is set.
[0029]
By the way, when the head controller 100 is in the low power energization mode B and the counter unit 14 counts a number n1 equal to or greater than n, when the mode B shifts from mode B to mode A as the state of the low power energization mode, heat is generated so far. Since the printing element in the non-heat storage area is energized, there is a problem that the energization power to the non-heat storage area is insufficient to cause printing fading.
[0030]
The present invention has been made in view of the above points, and an object of the present invention is to prevent insufficient energization of a printing element in a region that has not generated heat during printing in a recording apparatus using a line thermal head. It is to provide a thermal head control device.
[0031]
[Means for Solving the Problems]
The present invention, as the energization control to provide the required power at a predetermined time in a thermal head having a plurality of printing elements, at the same time printing element number to be printed is number number n than on that preset in one line using pulse duty ratio is large when, 1 if the print element number to be printed simultaneously during the line is less remote by preset number number n thermal head control device for the control performed using the pulse duty ratio is small in the smaller number of lines than the number n the number is set in advance of the printing elements are energized simultaneously selected during Printout, the counter is first that outputs an H level signal when the count continuously m times and signal output means, Ri by the H-level signal output from the first signal output means, and a small low-power energization mode than in the a conductible time printing of the m lines A temperature holding phase selecting unit that, the with the temperature holding phase selector is at the low power energization mode, the number of the printing elements wherein the energized simultaneously releases the low power conduction mode when it becomes more than n The thermal head control apparatus includes an energization adjusting unit that energizes the printing element with a pulse having a large duty ratio.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter , embodiments of the present invention will be described with reference to FIGS. 1 to 5 with reference to the drawings. In addition, what was demonstrated with the prior art uses the same referential mark, and abbreviate | omits the detailed description.
First, a schematic block diagram of a thermal printer will be described with reference to FIG. In the figure, 31 is a CPU (central processing unit) for comprehensively controlling the thermal printer. The CPU 31 is composed of a microprocessor and its peripheral circuits. A printing unit controller 33, a ROM (read only memory) 34, a RAM (random access memory) 35, and a communication I / F (interface) 36 are connected to the system bus 32 from the CPU 31.
[0033]
A printing unit 37 is connected to the printing unit controller 33, and a host computer 38 is connected to the communication I / F 36.
[0034]
The printing unit controller 33 corresponds to the printer main body control unit 3 in FIG. 5, and the printing unit 37 corresponds to the line thermal head 1 and the head controller 100.
[0035]
Various control programs are stored in the ROM 34, and various work areas are secured in the RAM 35.
[0036]
Next, with reference to FIG. 1, it is a block diagram which shows schematic structure of the head controller 100 as a thermal head control apparatus to which this invention is applied. The head controller 100 according to the present invention is obtained by adding a 50% pulse generator 101, a 30% pulse generator 102, an m line counter 103, and an m1 line counter 104 to the conventional head controller 2. Therefore, the same parts as those in FIG. 6 are denoted by the same reference numerals, and the description thereof is omitted.
[0037]
That is, the temperature holding period selection unit 15 is connected to the 50% pulse generation unit 101 and the 30% pulse generation unit 102 together with the 60% pulse generation unit 16 and the 40% pulse generation unit 17. The 50% pulse generation unit 101 and the 30% pulse generation unit 102 output to the temperature holding period selection unit 15 pulse signals having a duty ratio of 50% and 30%, respectively, of preset periods.
[0038]
The counter unit 14 counts the number of dot data (1) to be printed in one line (in 1280 bits). If the number is greater than a preset number, a switching signal (low level signal) indicating a high printing rate is obtained. ) Is output to the temperature holding period selection unit 15.
[0039]
Further, the count value of the number of dot data (1) counted by the counter unit 14 is output to the m line counter 103 and the m1 line counter 104.
[0040]
The m line counter 103 is a number of lines in which the number of dot data of n or more is continuous (hereinafter, the number of continuous lines having a printing rate of n or more), where n is a count value at which the counter unit 14 switches the switching signal. Or the number of lines in which the number of dot data of n or less continues (hereinafter referred to as the number of continuous lines having a printing rate of n or less).
[0041]
That is, when the m line counter 103 counts the number m (for example, 4) of continuous lines having a printing rate of n or more, the signal a (second signal output means) is set to H level and the temperature holding period selection unit 15 is set. Output.
[0042]
Further, when the m line counter 103 counts the number m (for example, 4) of continuous lines having a printing rate of n or less, the signal b (first signal output means) is set to H level and the temperature holding period selection unit 15 is set. Output.
[0043]
Further, when the m1 line counter 104 counts the number of continuous lines with a printing rate of n2 or less smaller than n, the signal c is set to H level and output to the temperature holding period selection unit 15.
[0044]
Here, the m line counter 103, the m1 line counter 104, the 50% pulse generating unit 101, the 30% pulse generating unit 102, the 60% pulse generating unit 16, the 40% pulse generating unit 17, and the temperature rising period timer 18 are used to adjust the energization. Is configured.
[0045]
Next, an embodiment of the present invention configured as described above will be described. First, a data read / output control signal is output to the data control unit 12, and a latch signal (strobe signal) is output to the latch circuit 8 at the timing when the print data of the shift register 91 line is set. An enable signal output control signal is output to the enable signal output unit 13 in accordance with the print timing.
[0046]
The data control unit 12 is connected to the print data memory 4 so as to be accessible on the basis of a data read output control signal. The print data memory 4 reads the print data for each line data (1280 bits). And output to the shift register 9 together with the counter unit 14.
[0047]
The counter unit 14 counts the number of dot data (1) to be printed in one line (in 1280 bits). If the number is larger than a preset number, a switching signal (low level) indicating a high printing rate is obtained. Signal) is output to the temperature holding period selection unit 15. In the subsequent operation, when the number of dots printed in one line is greater than or equal to the preset number, a switching signal is output to the temperature holding period selecting unit 15, and the temperature holding period selecting unit 15 outputs 60%. Description will be made assuming that a pulse is selected. Incidentally, when the number of dot data to be printed in one line is equal to or less than a preset number, the temperature holding period selection unit 15 selects 40% pulses.
[0048]
As described above, the counter unit 14 counts the number of dots printed in one line. Further, the number of continuous lines having a printing rate of n or more is counted by the m line counter 103. When four lines having a printing rate of n or more simultaneously energized printing elements are consecutive, the m line counter 103 sets the signal a to the H level.
[0049]
As a result, the temperature holding period selection unit 15 outputs a 50% pulse to the enable signal output unit 13 instead of the 60% pulse that has been output so far. That is, the low power energization mode A is set.
[0050]
Therefore, as shown in FIG. 2, until the fourth line, the temperature of the heating resistors 1-1 to 1280 of the line thermal head 1 rises between the melting point T2 of the resin-based ink and the heat resistance temperature T1 of the ink ribbon. However, since the low-power energization mode A starts from the fifth line, the temperature of the heating resistors 1-1 to 1280 of the line thermal head 1 is between the melting point T2 of the resin-based ink and the heat resistance temperature T1 of the ink ribbon. It goes down between.
[0051]
As described above, when four or more lines of the number of printing elements that are simultaneously energized and selected at the time of printing are continuously formed, the power consumption time is smaller than that of the four lines. Since the energization mode is set, it is possible to prevent the heat accumulation in the head from increasing even when four or more lines having a predetermined number n of printing elements are continuously formed. .
[0052]
In addition, when four lines having the number of printing elements simultaneously energized smaller than n continue for four lines, the signal b is output from the m line counter 103 to the temperature holding period selection unit 15 as H level.
[0053]
In response to this signal b, the temperature holding period selection unit 15 outputs a 40% pulse to the enable signal output unit 13 because the number of printing elements is n or less up to the fourth line. The% pulse is output to the enable signal output unit 13. That is, the low power energization mode B is set.
[0054]
As described above, since the energized power in the low power energization mode is made different depending on the number n, the power control can be accurately performed based on the number n.
[0055]
By the way, when the head controller 100 is in the low power energization mode B and the counter unit 14 counts a number n1 equal to or greater than n, the mode B is shifted from mode B to mode A as the state of the low power energization mode.
[0056]
When the mode B is shifted to the mode A in this way, the fact that the printing rate increases means that the printing elements in the non-heat storage area that has not generated heat until now are energized, as shown in FIG. There is a problem in that the energization power to the X2 region is insufficient to cause blurring of printing.
[0057]
Therefore, the head controller 100 does not shift from the low power energization mode B to the low power energization mode A, but when the counter unit 14 counts a number n1 of n or more in the low power energization mode B, The power energization mode is canceled and a 60% pulse is generated from the temperature holding period selection unit 15 to the enable signal output unit 13.
[0058]
As described above, when the number n of printing elements becomes n1 larger than n, the low power energization mode is canceled. Insufficient printing can be prevented.
[0059]
Further, when the counter unit 14 counts a number n2 equal to or less than n, for example, “0” in the low power energization mode, and the line continues for m1 lines, the thermal storage amount of the thermal head decreases. Therefore, for the energization occurring thereafter, the low power energization mode is canceled and normal energization control is performed.
[0060]
Thus, when in the low power conduction mode, when the number of the printing elements to be energized is preset line number m1 lines continuously simultaneously was n2 or less, so as to release the low-power energization mode As a result, when the number of printing elements becomes n2 or less, the heat storage amount of the head is attenuated, and it is possible to prevent printing from fading due to insufficient energizing power.
[0061]
In the above-described embodiment, the temperature holding period selection unit 15 includes 30% output from the 30% pulse generation unit 102, 40% pulse generation unit 17, 50% pulse generation unit 101, and 60% pulse generation unit 16. Although four pulses are input as a pulse, 40% pulse, 50% pulse, and 60% pulse, the present invention is not limited to this, and five or more pulses may be input.
[0062]
Further, although the energization adjusting means is performed in hardware, it may be performed in software.
[0063]
【The invention's effect】
According to the present invention, when the number of printing elements selected at the time of printing that is simultaneously energized is not more than n lines, the energization time is longer than that of m lines. As the small low-power energization mode, the low-power energization mode is canceled when the number n1 (> n) of printing elements is reached in the low-power energization mode. can do.
[0064]
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a heat generation state according to the embodiment of the present invention.
FIG. 3 is an explanatory diagram of an embodiment of the present invention.
FIG. 4 is a schematic block diagram of a thermal printer.
FIG. 5 is a diagram showing a configuration of a conventional form.
FIG. 6 is a diagram showing a configuration of a conventional head controller.
FIG. 7 is a timing chart.
FIG. 8 is an explanatory diagram of a heat generation state of a conventional form.
[Explanation of symbols]
2 Controller 13 Enable signal output unit 14 Counter unit 15 Temperature holding period selection unit 16 60% pulse generation unit 17 40% pulse generation unit 101 50% pulse generation unit 102 30% pulse generation unit 103 m line counter 104 m1 line counter signal a Second signal output means signal b First signal output means

Claims (2)

As energization control to provide the required power at a predetermined time in a thermal head having a plurality of printing elements, the duty ratio in the case of the number the number n other than the printing element number to be printed is set in advance at the same time in one line in the use of a large pulse, the thermal head control device for the control performed using the simultaneous pulse when the print element number is small preset number than the number n remote duty ratio is small to be printed in one line,
Fewer number of lines than the number n of the number of the printing elements to be simultaneously energized is selected when Printout is preset, the counter is a first signal output for outputting an H-level signal when it counts consecutively m times Means,
Ri by the H-level signal output from the first signal output means, and the temperature holding phase selector which the conductible time and low power energization mode printing is smaller than the time of the m lines,
When the temperature holding phase selecting unit of low power energization mode, the printing in the pulse duty ratio is large with the number of the printing elements wherein the energized simultaneously releases the low power conduction mode when it becomes more than n A thermal head control device comprising an energization adjusting means for energizing the element.   2. The thermal head control device according to claim 1, wherein the energization adjusting means has different energization power in the low power energization mode depending on the number of the printing elements energized simultaneously in one line.

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