JP2001047656A - Thermal printer apparatus and its program recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize high-peed printing according to an optimum maximum simultaneous drive dot number under the present state for individual products without being affected by an unevenness on products and a power source state by determining the maximum simultaneous drive dot number of a line thermal head during printing. SOLUTION: A CPU 1 calls up an 'initial value' of the number of dots to be driven simultaneously, prints dots of an amount corresponding to the number, and judges whether or not a printer supply voltage detected by a source voltage detect part 9 during printing reduces to a printer security voltage. Unless the printer supply voltage reduces to the printer security voltage, the simultaneous drive dot number is increased and updated, and printing dots of an amount based on the updated number are repeated. When the printer supply voltage reduces to the printer security voltage, the simultaneous drive dot number at the time is set as a maximum simultaneous drive dot number, and dots of an amount based on the set maximum number are printed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer apparatus for performing a printing operation by time-divisionally driving a thermal head with the maximum number of simultaneously driven dots capable of simultaneously driving heating elements constituting a line thermal head, and a program recording thereof. Regarding the medium.

[0002]

2. Description of the Related Art Conventionally, a line thermal printer device mounted on a word processor, a PDA (Personal Digital Assistant), or the like has a configuration having a plurality of heating elements in one line, such as 256 dots per line.
When all the heating elements in one line are driven during printing,
Since the power consumption is significantly increased, the maximum number of simultaneously driven dots that can simultaneously drive the heating elements is set as, for example, 64 dots, and the thermal head is driven in four divisions according to this maximum simultaneously driven dot number of “64 dots”. ing. In this case, as the set number of simultaneously driven dots increases, high-speed printing becomes possible. FIG. 6 shows an equivalent circuit during printing in this type of line thermal printer. Here, in the figure, “Va” is the power supply voltage, “R”
“a” is the power supply internal impedance, “Ia” is the printer supply current, “Vb” is the power supply output terminal voltage (printer supply voltage), and “Rb” is the circuit resistance other than the head (wiring resistance, power supply terminal contact resistance, power supply control switch) ON resistance),
“Rph” indicates the printer head resistance, and “N” indicates the maximum number of simultaneous color dots. In this case, the power supply voltage “V
"a", the power supply internal impedance "Ra", the printer head resistance "Rph", and the circuit resistance other than the head "Rb" are all constant. In addition, the power supply output terminal voltage “V
"b" is the power supply for driving the printer head and the power supply for the system.
A voltage drop occurs due to the power supply internal impedance “Ra”, and the power supply output terminal voltage “Vb” decreases. This can be expressed by the following equation. Vb = Va * (RB + Rph / N) / (Ra + Rb + Rph / N)} Further, the minimum power supply voltage of the power supply output terminal voltage "Vb" capable of operating the printer systematically, that is, the operation guarantee voltage of the printer Is "VLBP", the operation guarantee voltage "VLBP" of this printer needs to satisfy the following equation. VLBP <Vb ‥‥

By the way, the power source internal impedance "R
a ", the printer head resistance" Rph ", and the circuit resistance other than the head" Rb "are values of" variation "and battery characteristics during manufacturing, that is, changes in internal impedance due to repeated charging and discharging of the secondary battery. As a result, the power supply output terminal voltage “Vb” changes within the range of the oblique line shown in FIG. Here, “ΔVb” is affected by manufacturing variations and the like, so that the power supply output terminal voltage “V
b ”indicates the amount of change, and its maximum value“ Vbma ”
The power supply output terminal voltage “Vb” changes between “x” and its minimum value “Vbmin”. As described above, the power supply output terminal voltage “V
b ”changes, but VLBP ≦ Vb must be satisfied in order to enable the printer to operate, and the setting of VLBP = Vp is preferable in order to operate the printer efficiently. Are set to satisfy the minimum value “Vbmin” of the power supply output terminal voltage “Vb”.

[0004]

However, as described above, in the related art, the setting of the number of simultaneously driven dots is made in consideration of the influence of manufacturing variations and the like by changing the power supply output terminal voltage "Vb".
Is fixed to the worst value (the minimum value “Vbmin”), the same setting is applied to products other than the worst combination, and the power output terminal voltage “Vb” originally possessed by the product is Printing cannot be performed with the corresponding maximum number of simultaneously driven dots, and even though higher-speed printing is possible, there is no choice but to print at a general speed. An object of the present invention is to determine the maximum number of simultaneously driven dots that can simultaneously drive the heating elements constituting a line thermal head during a printing operation, so that it is not affected by variations in a product or a power supply state. It is to realize high-speed printing according to the maximum number of simultaneously driven dots that is optimal for printing.

[0005] The means of the present invention are as follows. According to a first aspect of the present invention, in a thermal printer apparatus that drives a thermal head in a time-division manner based on the number of simultaneously driven dots capable of simultaneously driving a plurality of dots among the dots constituting the thermal head, the thermal printer is set as an initial value in advance. First print control means for retrieving the number of simultaneously driven dots and simultaneously printing and outputting print data for the number of dots corresponding to the number of simultaneously driven dots, and detecting a printer supply voltage from a power supply during printing. Voltage detecting means, determining means for determining whether the printer supply voltage detected by the voltage detecting means has dropped to a predetermined voltage, and until the determining means determines that the printer supply voltage has dropped to the predetermined voltage, Update processing for updating the value by increasing the number of simultaneous drive dots and updated simultaneous drive A second print control unit for repeatedly executing a print control process for simultaneously printing out print data for the number of dots based on the number of dots, and the determination unit determines that the printer supply voltage has dropped to a predetermined voltage. A third print control unit that sets the number of simultaneously driven dots at that time as a maximum number of simultaneously driven dots, and prints out print data for the number of dots simultaneously based on the set maximum number of simultaneously driven dots. It is provided with. The present invention may be as follows. (1) When the battery is used as a power source, when the first printing is started after the battery replacement / battery charging is performed, the printer supply voltage from the power supply battery side is detected during the printing, and An update process of updating the value by increasing the number of simultaneously driven dots until it is determined that the supply voltage has dropped to the predetermined voltage, and print data for the number of dots based on the updated number of simultaneously driven dots is updated. At the same time, the print control process for printing out is repeatedly executed,
When it is determined that the printer supply voltage has dropped to a predetermined voltage, the number of simultaneously driven dots at that time is set as the maximum number of simultaneously driven dots. (2) When a battery is used as a power supply, a timer means for measuring an elapsed time since the maximum simultaneous drive dot number is set, and whether or not the time measured by the timer means has exceeded a predetermined time. A determining means for determining, and when it is determined by the determining means that the counted time does not exceed a predetermined time, the previously set maximum number of simultaneously driven dots is left as it is, and the counted time is reduced to a predetermined time. If it is determined that the number is exceeded, a control means for starting the resetting process for changing the maximum number of simultaneously driven dots is provided.

According to the first aspect of the present invention, the number of simultaneously driven dots set in advance as an initial value is called, and print data for the number of dots corresponding to the number of simultaneously driven dots is simultaneously printed and output. The printer supply voltage from the power supply side is detected at step, and it is determined whether the detected printer supply voltage has dropped to the predetermined voltage. As a result, the simultaneous operation is continued until it is determined that the printer supply voltage has dropped to the predetermined voltage. An update process for updating the value by increasing the number of drive dots and a print control process for simultaneously printing out print data for the number of dots based on the updated number of simultaneous drive dots are repeatedly executed. When it is determined that the voltage has dropped to the predetermined voltage, the number of simultaneous driving dots at that time is set to the maximum Set as, simultaneously printed out the dot number of the printing data based on the maximum number of simultaneously driven dots set. Therefore, by determining the maximum number of simultaneously driven dots that can simultaneously drive the heating elements constituting the line thermal head during the printing operation, the maximum number of dots that are optimal for the current state of each product is not affected by product variations and power supply conditions. High-speed printing according to the number of simultaneously driven dots can be realized.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1A is a block diagram showing an overall configuration of a data processing device provided with a line thermal printer. The data processing device is a small electronic device (for example, a portable information terminal) driven by a battery. The line thermal printer has, for example, a configuration having a heating element of 256 dots per line.
The maximum number of simultaneously driven dots that can drive the heating elements simultaneously is
It is not fixedly set in advance, and the optimal maximum number of simultaneous drive dots is determined during printing according to product variations and power supply conditions. Time-division driving is performed.

[0008] The CPU 1 is a central processing unit that controls the overall operation of the data processing device according to an operating system and various application software in the storage device 2. The storage device 2 includes, in addition to an operating system and various application software, a database,
It has a storage medium in which character fonts and the like are stored and its drive system. The storage medium 3 is fixedly provided or removably mountable, and is composed of a magnetic / optical recording medium such as a hard disk, a floppy disk, an optical disk, and a RAM card, and a semiconductor memory. The programs and data in the recording medium 3 are loaded into a RAM (static RAM, etc.) 4 under the control of the CPU 1 as needed. Further, the CPU 1 receives a program or data transmitted from another device through a communication line or the like and stores the program or data in the recording medium 3 or a program stored in a recording medium provided in another device. And data can be accessed and used via a communication line or the like. In addition, the CPU 1 has an input / output peripheral device such as an input device 5, a display device 6, a thermal printer 7,
A power supply voltage detection unit 9 for monitoring the battery power supply unit 8 is connected via a bus line, and the CPU 1 controls those operations according to an input / output program. The input device 5 has a keyboard and a pointing device, and inputs character string data and various commands. The display device 6 is a liquid crystal, a CRT, a plasma display device, or the like.

The thermal printer 7 is a line printer for printing a print pattern line by line. Although not shown, a thermal head having a heating element of 256 dots per line and an energizing control of the heating element constituting the thermal head are provided. And a timing control unit that supplies a timing signal to the head driver. This timing control unit controls the head driver to time-divisionally drive the thermal head according to the maximum number of simultaneously driven dots that can simultaneously drive the heating elements. The power supply battery unit 8 is a secondary battery, and the power supply voltage detection unit 9 constantly monitors the printer supply voltage supplied to the thermal printer 7 and detects the voltage value. Here, when the first printing is started after the battery is exchanged or the battery is charged, the CPU 1 sets the printer supply voltage supplied from the power supply battery unit 8 to the thermal printer 7 to a predetermined voltage during the printing. When the voltage drops to (the operation guarantee voltage of the printer), the maximum number of simultaneously driven dots is set. Note that the equivalent circuit at the time of printer printing in the thermal printer device is the same as that in FIG. 6 described above, and a description thereof will be omitted.

FIG. 1B shows a work area of the RAM 4, in which various parameters are set. Here, the various work areas function as counters, registers, and timers, and the area "X" is an addition counter whose value is updated by "1".
The area “n” is an initial value register in which an initial value of the number of simultaneously driven dots is set in advance. For example, this register stores “16 dots” as the initial value of the number of simultaneously driven dots.
Is set. The area "F" is a flag register in which a flag "0" is set when the battery is replaced or the battery is charged. When the maximum number of simultaneous driving dots is set, the flag "1" is stored in the register. Set. The area "N" is an updated value register in which the number of simultaneously driven dots updated by multiplying the value of the addition counter "X" by the value of the initial value register "n" is set. The area "Vb" is a detection voltage register in which the printer supply voltage detected by the power supply voltage detector 9 is set. The area "VLBP" is a set voltage register in which the operation guarantee voltage of the printer is set in advance. The area "t" is a timer for measuring the elapsed time from when the maximum number of simultaneously driven dots is set to when the next printing is started. The area "T1" is an elapsed time determination register in which a set time set in advance to determine whether the elapsed time measured by the timer has exceeded a predetermined time is set.

Next, a printing operation according to the embodiment will be described with reference to a flowchart shown in FIG. Here, a program for realizing each function described in this flowchart is stored in the storage medium 3 in the form of a readable program code, and the CPU 1 sequentially executes operations according to the program code. .

FIG. 2 is a flowchart showing a printing operation started when printing start is instructed. First, it is checked whether or not it is "1" by referring to the flag register "F" (step A1). Here, if the start of the first printing is instructed after the battery replacement or the battery charging is performed, the flag register "F" is set to "0". Counter "X"
After setting the initial value "0" to "1", "1" is added to the value (step A3). Then, the value of the addition counter "X" is multiplied by the number of simultaneous drive dots set in the initial value register "n", and the value is set in the update value register "N". Although the update is performed (step A4), since the value of the addition counter “X” is “1”, the number of simultaneously driven dots N = n1 after the update, that is, the initial value (16 dots) remains. I have. Then, a printing operation for simultaneously printing the print data of the number of dots corresponding to the updated initial value register "n" in the update value register "N" is performed (step A).
5). During this printing, when the power supply voltage detector 9 detects the printer supply voltage, the printer supply voltage is set in the detection voltage register “Vb” (step A).
6).

Then, the CPU 1 sets the detection voltage register “V
b "and the setting voltage register" VLB "
P ”and the printer operation assurance voltage in V, Vb> VL
It is checked whether it is a BP (step A7). As a result, if the printer supply voltage is higher than the printer operation guarantee voltage, the process returns to step A3, and the value of the addition counter “X” is updated.
In this case, X = 2, and the number of simultaneously driven dots in the update value register “N” is updated accordingly, so that the number of simultaneously driven dots N = n2 (32 dots) (step A4). Then, when a printing operation for simultaneously printing and outputting print data for the number of dots corresponding to the updated number of simultaneously driven dots is performed (step A5), the printer supply voltage is lower than that at the time of the previous detection. For this reason, the printer supply voltage and the printer operation guarantee voltage are compared again (step A7), and the printer supply voltage decreases until Vb> VLBP becomes unsatisfied, that is, with the update of the number of simultaneously driven dots. The above operation is repeated until the voltage reaches the printer operation guarantee voltage.

FIG. 3 is a diagram showing a voltage change when the printer supply voltage is reduced in accordance with the update of the number of simultaneously driven dots. When the value of the addition counter "X" is "3", FIG.
That is, when the number of simultaneously driven dots N = n3 after the update, Vb
> VLBP is detected. Note that the printer supply voltage Vb is equal to the power supply voltage Va during printing stop because no load is applied. However, when printing is started, when the number of simultaneously driven dots N = n1, the printer head resistance "Rph" ( Rph / n1)
As a result, a voltage drop occurs in the printer supply voltage Vb with respect to the power supply voltage Va according to the above equation.
b1 ”, but the printer supply voltage Vb1 is Vb1
Since> VLBP, this is detected in step A7, and the process returns to step A3. As a result, the number of simultaneously driven dots N = n2 (n1 <n2), and printing is performed with this number of simultaneously driven dots, but the printer supply voltage at this time is "Vb2". Since this voltage also satisfies Vb2> VLBP, the process returns to step A3 as described above.

As a result, the number of simultaneously driven dots N = n3 (n2 <n3), and printing is performed with this number of simultaneously driven dots (step A5). The printer supply voltage at this time is “Vb3”, and this voltage Vb3 is
Since 3 = VLBP, this is detected in step A7. Then, the process proceeds to step A8, where the number of simultaneously driven dots at that time is determined as the maximum number of simultaneously driven dots, the setting is performed, and "1" is set in the flag register "F" (step A9). Then, a printing operation for simultaneously printing and outputting print data for the number of dots corresponding to the set maximum number of simultaneously driven dots is performed (step A).
10). After that, the timer “t” is cleared and started,
The timer operation is started (step A11).

After the setting of the maximum number of simultaneous drive dots is performed, if the next printing start is designated, the flow chart of FIG. 2 is started again. Since "1" is set in the register "F", the fact is detected in step A1 and the process proceeds to step A12 to call the set maximum simultaneous drive dot number. Then, the elapsed time obtained by the time counting operation of the timer “t” is called (step A13), compared with the set time in the time determination register “T1”, and t <T
It is checked whether it is 1 (step A14). That is, in this embodiment, since the battery is used as the power supply, the power supply voltage Va decreases with the passage of time due to the heavy load of printer printing, battery self-consumption, and the like. The change state of the power supply voltage Va is checked according to the elapsed time until the start of printing this time.

FIG. 4 shows an example of a discharge curve of the power supply voltage Va. In FIG. First, after the previous printing end timing, if the time difference t12 from the current printing start timing is small, the power supply voltage Va at the printing end timing is set.
1 and the power supply voltage Va2 at the print start timing are substantially the same, and their voltage difference (ΔVa12) is negligible. Therefore, in this printing, printing is performed using the maximum number of simultaneously driven dots in the previous printing as it is. May be performed.
On the other hand, when the current print start timing is after the previous print end timing, the time difference t13 is large,
It is considered that the power supply voltage Va changes considerably according to the elapsed time. In this case, the voltage difference (ΔVa13) between the power supply voltage Va1 at the previous printing end timing and the power supply voltage Va3 at the current printing start timing is large, and the maximum simultaneous drive dot number at the previous printing is used as it is at the current printing. If printing is performed by the printer, the printer supply voltage greatly interrupts the printer operation guarantee voltage and the system may be down. Therefore, the maximum number of simultaneously driven dots is reset.

That is, as a result of the comparison judgment in step A14, if the elapsed time from the end of the previous printing to the start of the current printing does not exceed the set time, the process proceeds to step A10. Printing is performed using the maximum number of simultaneous drive dots during the previous printing as it is, but if the time from the end of the previous printing to the start of the current printing has exceeded the set time, the power supply voltage Va will be significantly increased. Since a drop is expected, the process returns to step A2, and the above operation is repeated to newly calculate the maximum simultaneous drive dot number (steps A3 to A7), and based on the maximum simultaneous drive dot number obtained thereby. To print this time.

As described above, in this embodiment,
The simultaneous drive dot number “initial value” is called, printing is performed for the number of dots corresponding to the simultaneous drive dot number, and it is determined whether the printer supply voltage has decreased to the printer security voltage during printing. Until the supply voltage drops to the printer security voltage, the number of simultaneously driven dots is increased, and the value is updated and printing for the number of dots is repeatedly executed based on the updated number of simultaneously driven dots. When the voltage drops to the printer guarantee voltage, the number of simultaneously driven dots at that time is set as the maximum number of simultaneously driven dots, and printing is performed for that number of dots based on the set maximum number of simultaneously driven dots. The number of simultaneously driven dots can be determined during the printing operation, so that the product Status quo to optimum maximum simultaneous high-speed printing in accordance with the drive number of dots can be realized of.

Further, when the first printing is started after the battery replacement / battery replacement, the maximum number of simultaneous driving dots is set during the printing. Since the printing operation can be performed using the maximum number of simultaneous drive dots set at the first printing,
There is no need to set the maximum number of simultaneous drive dots for each print,
This is more advantageous in realizing high-speed printing. In this case, the elapsed time from when the maximum number of simultaneous driving dots is set is measured, and it is determined whether or not the time has exceeded a predetermined time, and it is determined that the time has exceeded the predetermined time. In order to change the maximum number of simultaneous drive dots, the optimal number of simultaneous drive dots is determined so that it is not affected even if the voltage is greatly reduced when using a battery as a power supply. Can be reset.

In the above-described embodiment, if it is determined that the time measured from the previous printing to the current printing exceeds a predetermined time, the time is counted again to change the maximum number of simultaneously driven dots. The setting was made, but FIG.
As shown in (1), the maximum number of simultaneously driven dots may be reset to a value smaller than the currently set maximum number of simultaneously driven dots. That is, FIG. 5 is a flowchart schematically showing the resetting in this case, and the execution is started when the value of the flag register “F” is “1”. First, the elapsed time from the end of the previous printing to the start of the current printing is obtained from the timer "t" (step B1), and this elapsed time is compared with the set time in the time determination register "T1" (step B2). ,
If the elapsed time does not exceed the set time, the current printing is performed using the maximum number of simultaneously driven dots of the previous printing as it is (steps B3 and B4), but from the end of the previous printing to the start of the current printing. If the time exceeds the set time, the maximum number of simultaneous drive dots at the time of previous printing is smaller than the maximum number of simultaneous drive dots, and it is reset. The current printing is performed according to the maximum number of simultaneously driven dots (steps B5 and B4).

In the above-described embodiment, the number of simultaneously driven dots is updated by multiplying the number of simultaneously driven dots as the preset initial value by an integer. The number of simultaneously driven dots may be updated while adding (for example, 8 dots). In this way, by updating while adding a predetermined value to the initial value, it is possible to finely set the maximum number of simultaneously driven dots.

[0023]

According to the present invention, the maximum number of simultaneously driven dots capable of simultaneously driving the heating elements constituting the line thermal head is determined during the printing operation, so that variations in products and power supply conditions are affected. Instead, it is possible to realize high-speed printing according to the maximum number of simultaneous driving dots that is optimal for the current state of each product.

[Brief description of the drawings]

FIG. 1A is a block diagram showing the overall configuration of a data processing apparatus provided with a line thermal printer, and FIG.
The figure which showed the work area in AM4.

FIG. 2 is a flowchart illustrating an operation when a print start is designated.

FIG. 3 is a diagram illustrating a change in a printer supply voltage when a maximum simultaneous drive dot number is set during a printing operation.

FIG. 4 is a diagram illustrating a state in which a power supply voltage is reduced in accordance with a printing operation and the like.

FIG. 5 is a flowchart for explaining a modified application example of the present invention.

FIG. 6 is a block diagram showing an equivalent circuit at the time of printing in a general thermal printer device.

FIG. 7 is a diagram showing a change in a printer supply voltage according to a variation in a product or a power supply state in the related art.

[Explanation of symbols]

 Reference Signs List 1 CPU 2 storage device 3 storage medium 5 input device 6 display device 7 thermal printer 7 8 power supply battery unit 8 9 power supply voltage detection unit 9 “X” addition counter “n” initial value register “N” update value register “Vb” detection Voltage register “F” Flag register “VLBP” Set voltage register “t” Timer “T1” Time judgment register

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C061 AQ04 HK18 2C066 AA03 AA08 AB03 AB07 CB01 CB03 CB06 CB09 CF03 CF08 5B021 MM00 MM03

Claims (4)

[Claims] 1. A thermal printer in which a thermal head is driven in a time-division manner based on the number of simultaneously driven dots capable of simultaneously driving a plurality of dots out of the dots constituting the thermal head, a simultaneous printer which is preset as an initial value. First print control means for calling the number of drive dots and simultaneously printing and outputting print data for the number of dots corresponding to the number of simultaneous drive dots; voltage detection means for detecting a printer supply voltage from a power supply during printing; Determining means for determining whether the printer supply voltage detected by the voltage detection means has decreased to a predetermined voltage; and determining whether the printer supply voltage has decreased to the predetermined voltage by the determination means. The update process that updates the value by increasing the number and the updated number of simultaneous driving dots A second print control means for repeatedly executing print control processing for simultaneously printing out print data for the number of dots, and when the determination means determines that the printer supply voltage has dropped to a predetermined voltage, A third print control unit that sets the number of simultaneously driven dots at that time as a maximum number of simultaneously driven dots, and simultaneously prints and outputs print data for the number of dots based on the set maximum number of simultaneously driven dots. A thermal printer device characterized by the above-mentioned. 2. When using a battery as a power source, when the first printing is started after the battery replacement / battery charging is performed, the printer supply voltage from the power supply battery side is detected during the printing. An update process of updating the value by increasing the number of simultaneously driven dots until it is determined that the printer supply voltage has dropped to a predetermined voltage, and printing the number of dots based on the updated number of simultaneously driven dots. Print control processing for simultaneously printing out data is repeatedly executed, and when it is determined that the printer supply voltage has dropped to a predetermined voltage, the simultaneous drive dot number at that time is set as the maximum simultaneous drive dot number. 2. The thermal printer according to claim 1, wherein: 3. When a battery is used as a power supply, a timer means for measuring an elapsed time after the maximum simultaneous drive dot number is set, and whether or not the time measured by the timer means exceeds a predetermined time. Determining means for determining whether or not the time counting time does not exceed a predetermined time, leaving the already set maximum number of simultaneous driving dots as it is, and 2. The thermal printer device according to claim 1, further comprising control means for starting a resetting process for changing the maximum simultaneous drive dot number when it is determined that the time has elapsed. . 4. A recording medium having a program code which can be read by a computer, the method comprising calling a simultaneous drive dot number set as an initial value in advance, and printing print data for the number of dots corresponding to the simultaneous drive dot number. A computer readable program code that prints simultaneously and a computer readable program that determines whether the detected printer supply voltage has dropped to a predetermined voltage when the printer supply voltage from the power supply is detected during printing Until it is determined that the printer supply voltage has dropped to a predetermined voltage, an update process of updating the value by increasing the number of simultaneously driven dots and the updated number of simultaneously driven dots are performed based on the updated program code. A print control process that prints out the print data for the number of dots simultaneously A computer readable program code to be repeatedly executed, and when it is determined that the printer supply voltage has dropped to a predetermined voltage, the simultaneous driving dot number at that time is set as a maximum simultaneous driving dot number and set. And a computer-readable program code for simultaneously printing and outputting print data for the number of dots based on the maximum number of simultaneously driven dots.