JPH0752433A - Thermal line printer and recording method used in the printer - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a thermal printer capable of high-speed printing without being influenced by the high-low temperature discharge characteristics of a battery and capable of executing a plurality of printing modes, and a recording method thereof. To do. A thermal printer according to the present invention and a recording method used for the printer measure a surface temperature of a battery, and simultaneously determine the number of heating elements to be heated to correspond to the process of the measured battery surface temperature. Let me decide. Further, a plurality of print modes are realized by changing the number of the heating elements to be heated at the same time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal line printer driven by a rechargeable battery and a recording method used in the printer.

[0002]

2. Description of the Related Art In a conventional portable information device driven by a battery, for example, when the remaining battery power falls below a certain level, the process being executed is interrupted, and necessary data and the like are stored in a memory before the operator Has a function to notify the battery replacement (low battery processing). The detection of the remaining battery level is widely used based on the change in the battery voltage, and the outline thereof will be described with reference to FIGS. 13 and 14.

In the circuit of FIG. 12, a load circuit section 121 is a circuit in which all units to which current is supplied from a battery 122 are arranged in parallel. In this figure, a CPU unit 123, an LCD unit 124 and a printer unit 1 are shown for convenience.
Although only 25 is shown, of course, it is not limited to this. The current I flowing through the load circuit constantly changes according to the operating state of each unit. At the same time the battery output voltage V
Also fluctuates momentarily.

Where Z is the internal impedance of the battery, i
₁ is the current drawn from the battery, C is the capacitor connected in parallel, and i ₂ is the current flowing through it.

[0005]

## EQU1 ## There is a relation of I = i ₁ + i ₂ .

On the other hand, as a whole, the battery voltage draws a discharge curve shown in FIG. That is, the voltage drops according to the elapsed time and is affected by the battery temperature. In the figure, reference numeral 131 indicates the case of printing under the condition of simultaneous heating 32 dots, 132 indicates the case of simultaneous heating 20 dots, and 133 indicates the case where the printer is stopped and the other parts are driven. The battery temperatures are 0 ° C., 20 ° C. and 40 ° C., respectively. Further, the points L indicate respective low battery generation points.

The voltage for starting the low battery processing is conventionally set to the minimum guaranteed voltage of each electronic component used in the apparatus plus about 0.2 V (5.0 V in the example of FIG. 13).

In recent years, low power consumption of electronic parts has progressed, and most of these battery consumptions have been spent on driving mechanical parts such as a printer unit.

In the thermal printer unit, as shown in FIG. 14, 6 blocks (1 block = 64 dots) 384 controlled by 6 strobe signals (head energization signals).
The number of simultaneous heating dots (maximum value) = 6
Use 4 dots. The total number of black dots on the dot line 1 shown in FIGS. 15 and 16 is 60 dots (the portions corresponding to blocks 1 to 6 are 10 dots each), and the total black dots on the dot line 2 is 110 dots (block 1 = In order to obtain a print result of 40 dots, block 2 = 30 dots, block 3 = 10 dots, blocks 4 and 5 = 5 dots, block 6 = 20 dots, the circuit of FIG. 14 is shown in FIG. It is realized by controlling the timing from A to E.

A: Data to be printed at the timing of stop state B is transferred to the thermal head shift register for one line.

B: Print data output of line 1 Ba: The print data for one line transferred by A is latched (stored) in the latch register of the thermal head, and 64
Energization of the thermal head is started by a strobe signal (DST signal) with dots as one unit. As described above, the total number of heat dots is 60 dots, which is less than the above number of simultaneous heat dots, so printing is performed once.

B-b: The print data for the next one dot line is transferred to the head.

C: Paper feeding B-a, after which the motor is driven to feed one dot of paper.

D: Print data output of dot line 2 The print data for one dot line transferred at the timing of B-b is latched (stored) in the latch register of the thermal head, and a strobe signal (64 dots as one unit) ( Energization of the thermal head is started by the DST signal). As described above, the total number of heat dots is 110 dots, which is larger than the number of simultaneous heat dots described above, and therefore printing is performed twice, 60 dots and 50 dots.

E: Paper feeding After the timing of D, the motor is driven to feed one dot of paper.

As described above, in the conventional printing method, the size of the number of simultaneous heat dots is a factor that determines the printing speed. Moreover, the number of simultaneous heat dots determines the load applied to the battery so that the memory effect does not occur when the battery temperature is low (when the battery discharge efficiency is poor in the above description).

[0017]

However, in the conventional printing method, the number of simultaneous heat dots depends only on the low temperature discharge characteristic of the battery, and no consideration is given to the high temperature discharge characteristic of the battery.

Therefore, a first object of the present invention is to solve the above-mentioned problems and to provide a thermal printer and a recording method therefor that are faster than conventional ones without being affected by the high-low temperature discharge characteristics of the battery.

A second object of the present invention is to provide a thermal printer which can select a power mode which enables high speed printing of the printer in a battery driven thermal printer and an economy mode which increases the number of printing lines of the printer, and a recording method thereof. To provide.

[0020]

In order to solve the above problems, therefore, a thermal printer and a recording method therefor according to the present invention use a battery as a power source and a plurality of heating elements arranged in a line direction orthogonal to the paper feeding direction. In a recording method of a thermal line printer that performs thermal recording with a arranged thermal line head, the surface temperature of the battery is measured, and the number of heating elements to be heated at the same time corresponds to the measured surface temperature of the battery. It is characterized in that a plurality of printing modes are realized by changing the number of the heating elements to be simultaneously heated.

[0021]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a perspective view of a portable computer device for carrying out a recording method according to the present invention. Reference numeral 1 is a main body, 2 is a thermal line printer for printing information processed by the main body 1, and 3 is a thermal line printer. An input key for inputting data to the main body 1 and a liquid crystal display device 4 for displaying information.

FIG. 2 is a rear view of the portable computer device shown in FIG. 1, and reference numeral 5 is a rechargeable battery pack for driving the main body 1. In this pack 5, five CADNICA batteries having an open voltage of 1.2 V are connected in series, and the nominal voltage is 6 V and the discharge end voltage is 5.0 V. Further, a thermistor is placed inside, and a change in the battery surface temperature inside the battery pack 5 can be measured as a change in the thermistor resistance through a connection terminal (not shown).

(Basic Structure of Printer) FIG. 3 shows the basic structure of the printer indicated by reference numeral 2 shown in FIG.
Reference numeral 31 is a thermal line head unit, 32 is a cable, 33 is a head mounting plate, 34 is a mounting plate shaft, 35 is a spring, 36 is a platen roller, 37 is a stepping motor, and 38 is a gear.

The thermal line head unit 31 is fixed to the head mounting plate 33. The heating element of this thermal line head unit 31 is 0.125 mm ²
The number of such heating elements is 512 in a row, and the platen roller 36
Face to face. The mounting plate shaft 34 is combined with the head mounting plate 33, both ends of which are supported by the printer unit main body (not shown), and the head mounting plate 33 is rotatable about the shaft 34 as a fulcrum. The spring 35 has an upper end on the printer unit body,
Further, the lower end portions are attached to the head attachment plate 33, and the head 31 is brought into close contact with the platen roller 36. The platen roller 36 has both ends of its shaft supported by the printer unit main body, is rotatable about the shaft, and one end thereof is driven by a stepping motor 37 via a gear 38.

A printing method by the printer configured as described above will be described below.

When thermal paper is inserted between the head 31 and the platen roller 36 and print data is sent from the main body control unit (not shown) to the thermal line head unit 31 by a method described later, out of 512 heating elements. The heating signal is sent to the heating element to which the data of “1” is input, so that the heating element is heated, and the portion of the surface of the thermal paper facing the head that is in contact with the heated heating element is almost Discolored by the same area as the heating element. After that, the platen roller 36 is driven by the stepping motor 37, and the paper is fed by the frictional force between the platen roller 36 and the thermal paper. The feed amount is 0.063 mm which is half the length of one side of the heating element when the stepping motor 37 is moved one step.

(Description of Electric Block of Portable Computer) FIG. 4 is an electric block diagram of the thermal line printer having the above-mentioned configuration. The voltage value of the rechargeable battery 5 is converted by an 8-bit digital output A / D converter 42 and then input to the I / O port of the CPU 41. This A /
The D conversion is continuously performed at a constant cycle, and the internal register of the CPU 41 always writes a value corresponding to the latest battery voltage. Further, reference numeral 64 is a thermistor provided inside the battery pack 5 for detecting the battery surface temperature, and the value of the battery surface temperature after A / D conversion is written in the internal register of the CPU 41 like the battery voltage. . Reference number 4
4 is R in which programs and character fonts are stored
An OM 45 is a RAM that stores the character font and the print mode of the printer selected by the user. R
The OM 44, the RAM 45 and the CPU 41 are connected by an address bus and a data bus. Reference numeral 5
4 is a stepping motor unit for feeding the paper CP
Two excitation signals 56 and hold signal 5 from U41
It is controlled by 5. Reference numeral 50 is a 512-dot thermal line head 47 composed of 512 heating elements.
And a 512-dot latch register 4 for temporarily storing the print data currently being heated corresponding to 1 dot = 1 dot
8 and temporarily store print data for next heat 5
A thermal line head unit composed of a 12-bit shift register 49, which controls a print data transmission signal 51, a latch signal 52 for controlling data transfer from the shift register to the latch register, and heat execution of the heating element by the latch data. It is controlled by the CPU 41 by the strobe signal 53 which is generated. The strobe signal 53 is connected to the gates of all 64 × 8 blocks (512) as shown in FIG. 5, and the heat execution of all 512 heating elements can be controlled by one control signal. it can. Reference numeral 60 denotes an interrupt generation circuit that activates the interrupt signal 61 to the CPU 41 to issue an interrupt when the battery voltage becomes 5.0 V (discharge end voltage) or less. The CPU 41 executes an interrupt sequence described later, and then performs an interrupt clear signal. The interrupt signal is made inactive by 62. 63 is a thermistor for detecting the temperature of the device, which is an A / D of the device temperature similar to the battery voltage.
The converted value is written in the internal register of the CPU 41.

(Control of Thermal Printer) Regarding the flow of control of the thermal line printer having the above configuration, FIG.
A more detailed explanation will be given (in the following description, "h" is a hexadecimal display, "b" is a binary display, and a decimal display when nothing is attached).

The CPU 41 combines the character fonts stored in the ROM 44 and develops the character font of one character string on the RAM 45 as a bit image (S).
-1). For example, in a printer using a 512-dot line head as in this embodiment, when developing a font of 8 × 16 dots shown in FIG.
You can develop 4 characters (3Fh). In the expansion example of FIG. 7, 49 characters (30h-0h + 1) are expanded from H to I. In this case, 1 dot string is printed, and 010000h is set as the start pointer which is the first 1-byte address on the RAM.
Is 0100 as the end pointer indicating the final expansion character.
30h is (S-2), and the number of dot rows is 16 (S-3)
Each is set.

The CPU 41 turns on the hold signal 55 and switches the excitation signal 56 to rotate the stepping motor 54 one step. This driving force is transmitted to the above-mentioned paper feed system and the paper is fed by an amount corresponding to one step of the motor (S-4). In this embodiment, half the length of one side of the heating element is set as the paper feed amount per step.

Next, 1-dot row printing is performed by the method described later (S-5).

When one dot row printing is completed, the start pointer / end pointer is advanced by 64 and the number of dot rows is decremented by 1 to prepare for the next one dot row printing (S-6, S-7).

In the expanded example of FIG. 7, start pointer = 0
10040h, end pointer = 010070h, and dot row number = 15.

Next, the number of dot rows is determined (S-8), and if it is not 0, one-step paper feed is executed (S-4). Here, the 1-dot printing paper has been fed from the start of the previous 1-dot row printing (1-step paper feeding executed in the 1-dot row printing subroutine described later and 1-step paper feeding of S-4).

Then, the above 1 dot row printing, the start / end pointer +64, and the dot row number -1 are repeated, and when the dot row number becomes 0, that is, the last 1 dot row of the font expanded on the RAM is printed. Is completed, the printing of one character string is completed (S-9).

(Description of 1-Dot Row Printing) Next, 1-dot row printing (S-5) (including 1-step paper feeding during recording)
The method will be described with reference to FIGS. 8 and 9.

There is a time lag between the one-step paper feed control by the CPU 41 and the actual movement of the paper, and the surface of the paper vibrates for a while even after the movement. Therefore, it is necessary to wait for a fixed time of printing controlled by the timer 46. I won't. Therefore, the motor hold signal 55 is turned off after the timer 46 measures the fixed time (S-10).

Generally, the hold signal of the step motor is always turned on during the operation of the motor, but in the present embodiment, in order to suppress the power consumption as much as possible due to the nature of the portable computer, as described above, within the minute time of 1 dot printing. (~
Even if it is 10 msec), it is devised to turn it off when unnecessary.

As an initial process for printing one dot line (line), the CPU 41 performs the following process (S-11).

A) The battery surface temperature value by the A / D converter 42 is set by determining the number of simultaneous heat dots by a method described later based on the data in the internal register written by the above method.

B) Reset the byte counter that counts the bytes that have been printed.

C) The start pointer value is set in the get pointer (S-11).

Next, R of the value indicated by the get pointer
1 byte of print data is C from the address on AM45
It is read by the PU 41 (S-12).

(Data Transfer Processing for Simultaneous Heating) In a portable computer, it is sometimes difficult to heat all the heating elements at the same time due to the limited battery capacity. In this case R
Print data for 1 dot line (line) on AM45
It is divided into partial data having the number of simultaneous heat dots (for example, 24 dots), divided into several times, and printed in time series.

For this purpose, the number of "1" (that is, the number of heat dots) in the 1-byte data read from the RAM 45 is calculated by using a look-up table preset in the ROM 44 in advance.

This lookup table is 00h-FF
Bit "1" corresponding to (input value) for each byte data of h
Is a data string of 256 in which the number (output value) of is written.

The CPU 41 subtracts the determined number of heat dots from the number of simultaneous heat dots (S-13).

When it is determined that the subtraction result is larger than "0", that is, the read 1-byte data heat is possible, the CPU
41 outputs 512 bytes of this 1-byte data from the serial port.
Transfer to the bit shift register 49 (S-14, S-
15). The number of simultaneous heat dots is determined by a method described later based on the A / D converted value of the voltage of the thermistor that reacts to the battery surface temperature (measured temperature of the first invention).

In the example of FIG. 7, when the get pointer is 010000h by the processing of S-13 to S-15, the 1-byte data indicated by this pointer is 1100 in binary notation.
At 0110b, the number of remaining heat dots is 20 (24-4 = 20) because there are four "1" s in this data. That is, it is determined that this 1-byte data can be heated.

Therefore, the CPU 41 advances the get pointer and the byte counter in order to process the next 1-byte data (S-16).

In the development example of FIG. 7, get pointer = 01
Since 0001h and end pointer = 010030h, the CPU 41 confirms that reading of all print data has not been completed and printing of 1/2 line has not been completed (negative determination in S-17, S- 18), the procedure is returned to S-12, and the above-described processing for transferring the next 1-byte print data to the 512-bit shift register 49 is executed.

The loop between S-12 and S-18 is repeated, and when the number of simultaneous heat dots remains less than "0", that is, when the partial print data is stored in the shift register by the set number of heat dots. (Yes in S-14), a part of the 1-byte data (original data) currently being processed is masked from the LSB direction by the 1-byte mask data so that the number of simultaneous heat dots becomes the set number (S-20 ), The 1-byte data after the mask processing is transmitted to the shift register (S-21).

As described above, in the present embodiment, one strobe signal 53 is used to control all 512 heating elements, so that the heating elements corresponding to the unprocessed byte data do not generate heat and fill up to 512 dots. No bytes (64 bytes-
Byte counter) Space data (00h) is transmitted to the shift register (S-22).

Wait for the end of the previous heat (S-
23), the CPU 41 sends a latch pulse to the latch register 48 of the head. As a result, the 512-bit print data previously stored in the shift register 49 by the above method is transferred in parallel to the latch register 48, and the shift register becomes ready to receive the 512-bit print data for the next heat.

After that, when the CPU 41 turns on the strobe signal 53, 512 set in the latch register is set.
The heating of the heating element corresponding to the bit for which "1" is set in the print data of the bit is started (S-2
4).

The strobe signal 53 is kept on by the timer 56 for a certain period of time (about 0.8 to 0.9 msec until the heat generating element becomes hot and the heat-sensitive paper develops color), and then is turned off.

When the heat is started, the CPU 41 starts data transfer to the shift register 49 for the next heat. First, the processed space data for the byte counter (00h) is transmitted (S-25). Bits that could not be transferred in S-20 by masking the original data in S-20 with the data obtained by inverting "0" and "1" of the 1-byte mask data used in S-20. 1-byte data corresponding to
-26), set the value of the above determination (S-4 of FIG. 6) to the number of simultaneous heat dots that is "0" (S-27),
It branches to the routine of S-13.

As described above, in the present embodiment, A. Data of 1 byte is transferred to the shift register until the number of simultaneous heat dots becomes 0 (processing of S-12 to S-18).

B. Unprocessed byte space data in 64 bytes is transferred to the shift register (S-14 to S
-22 processing).

C. Heat (processing of S-23 and S-24). And D. The processed byte space data is transferred to the shift register (processing of S-25 to S-27).

One dot line is printed by repeating the sequence from A to D above. That is, 64 bytes (512 bits) of data is always transferred before one heat.

(Control for Stick of Thermal Printer) The stick here means that the chemical applied to the surface of the thermal paper discolors and solidifies when cooled, so that the force for adhering the head to the paper is This is a phenomenon that occurs and becomes a resistance to the paper feeding force. This is a phenomenon that hinders smooth paper feeding and may cause uneven printing.

Next, the control for the stick countermeasure will be described.

When the byte counter reaches 32 after repeating the above sequences A to D (S-19 positive determination),
In other words, if processing up to 31 bytes corresponding to half of 512 dots up to 256 dots is completed, 3
2-byte space data transmission (S-28 in FIG. 9), waiting for the end of the previous heat (S-29), heat (S-30)
After that, the paper is fed by one step (S-31).

In this embodiment, 1 step = 0.5 dots is used, and the first half 25
The difference in level between the 6 dots and the latter half of the 256 dots is designed to be as inconspicuous as possible. After that, a flag indicating execution of intermediate paper feed is set (S-32), an initial value is set for the number of simultaneous heat dots (S-33), and control is performed before the transition, that is, branching to S-12 in FIG. (S-3
4) Then, the above sequence A to D is repeated again.

When the 1-byte transmission of I (S-15 in FIG. 8) is completed and the get pointer / byte counter is advanced (S-16) in the expanded example of FIG. 7, get pointer = 010031h.
Becomes At this point, the get pointer> the end pointer (affirmative determination in S-17), the CPU 41 determines that the characters are not expanded thereafter, and the final heat treatment A in one dot row (S-35 in FIG. 9). ).

The CPU 41 transmits space data of (64-byte counter) bytes (S-35 in FIG. 9) and waits for the end of the previous heat (S-36), as in the case of B.
The final heat in the 1-dot row is executed (S-37).
In the printing of the character font expansion example of FIG. 7, the one-step paper feed is already executed at the intermediate point of the one-dot row and the intermediate paper feed flag is set as described above. Therefore, the flag is cleared (S-41), and the one dot row printing subroutine is completed (S-42).

On the other hand, for example, when only 5 characters are font-developed, the paper feeding at the intermediate position is not executed, and the process branches to the final heat processing in this 1-dot row. Therefore, waiting for the end of the final heat (S-39), the paper feed of one step is executed (S-40). After this, the 1-dot string printing subroutine is ended, and the execution procedure is returned to S-6 in FIG.

(Method of determining the number of simultaneous heat dots) FIG.
Is a graph showing the magnitude of the voltage drop from the battery terminal open voltage with respect to the battery surface temperature when the number of simultaneous heat dots of the thermal printer is constant, and the voltage drop Va of the battery voltage is the internal impedance Z of the battery. It is the product of the current I flowing through the thermal printer. Further, the mark a is a voltage drop value (0.4 V in this embodiment) at which the battery 5 does not cause a memory effect in this system. The operating temperature range of the portable computer device equipped with the present thermal printer is 0 to 40 ° C. From FIG. 9, in order to use the battery without causing the memory effect, for example, the temperature is lower than the point b (10 ° C.). On the other hand, the maximum number of simultaneous heat dots is 20 dots. For example, if the value of the number of simultaneous heat dots is 24 dots, Va = 0.6 V at 2.5 ° C., and the battery will have a memory effect. From this, the maximum number of heat dots is 24 dots at a temperature lower than the point c (18 ° C), and the maximum number of heat dots is 36 dots at a temperature lower than the point d (26 ° C). Become.

FIG. 11 is a diagram showing the value of the number of simultaneous heat dots with respect to the surface temperature of the battery in this embodiment. The number of simultaneous heat dots is determined from the value of FIG. 10 described above so that the memory effect does not occur. is there. In addition, there is a high-speed mode that sets the number of simultaneous heat dots to increase from a low temperature, and an economy mode that reduces the number of simultaneous heat dots to suppress rapid battery consumption. It can be selected depending on the status.

Here, a method of determining the number of simultaneous heat dots in the high speed mode will be described. When the battery surface temperature read by the CPU 41 is 11 ° C., FIG.
The number of simultaneous heat dots is set to 1 to 20 dots.
Then, when printing is repeated, the battery temperature gradually rises, and when the temperature exceeds 12 ° C., the number of simultaneous heat dots is changed to 24 dots. Next, if the battery temperature becomes low due to some phenomenon, the number of heat dots is changed to 20 dots, but when the number of dots is reduced to prevent the heat dots from changing line by line due to a slight change in the battery temperature, 2 is set when the number of dots is reduced.
It has a hysteresis of ° C, and it is changed to 20 dots when the battery temperature falls below 10 ° C. (24 to 36
The same hysteresis is given when changing to dots. (Other Embodiments) In the present embodiment, the number of simultaneous heat dots is changed so as to switch the load current value to the printer according to the battery surface temperature, but the load current is also applied when driving a floppy disk unit, a hard disk unit, or the like. The present invention can be applied by controlling the value to be variable.

[0073]

As described above, according to the present invention, the number of heat-generating pairs driven at the same time can be varied according to the surface temperature of the battery, so that the memory effect of the battery does not occur and the operating environment of the device is reduced. Thus, it is possible to provide a high-speed thermal printer and a recording method for the printer, which prevent rapid battery consumption as compared with the related art. Further, according to the present invention, in the battery-driven thermal printer, it is possible to select the power mode which enables high speed printing of the printer and the economy mode which lengthens the number of printing lines of the printer.

[Brief description of drawings]

FIG. 1 is a perspective view of a portable computer device for carrying out a recording method according to the present invention.

2 is a rear view of the device shown in FIG. 1. FIG.

FIG. 3 is a diagram for explaining a basic structure of a printer included in the device shown in FIG.

FIG. 4 is an electrical block diagram of a thermal line printer.

FIG. 5 is an electrical block diagram of a thermal line printer.

FIG. 6 is a flowchart for explaining a control flow of the thermal line printer.

FIG. 7 is a diagram for explaining font expansion.

FIG. 8 is a flowchart illustrating a method of 1-dot row printing.

FIG. 9 is a flowchart following FIG. 8 for explaining the method of 1-dot row printing.

FIG. 10 is a graph showing the magnitude of the voltage drop of the battery voltage with respect to the battery surface temperature.

FIG. 11 is a graph showing the number of simultaneous heat dots with respect to the battery surface temperature.

FIG. 12 is a diagram for explaining a decrease in battery voltage of a conventional recording apparatus.

FIG. 13 is a diagram for explaining a battery discharge curve of a conventional recording device.

FIG. 14 is a block diagram for explaining a driving method of a conventional thermal line printer.

FIG. 15 is a block diagram for explaining a conventional method of driving a thermal printer unit.

16 is a partially enlarged view of an XV portion of FIG.

FIG. 17 is a diagram for explaining drive timing of a conventional thermal line printer.

[Explanation of symbols]

 1 Portable Computer Main Body 2 Thermal Line Printer Main Body 3 Input Key 4 Liquid Crystal Display 5 Rechargeable Battery 31 Thermal Line Head Unit 32 Cable 33 Head Mounting Plate 34 Mounting Plate Shaft 35 Spring 36 Platen Roller 37 Stepping Motor 38 Gear 41 CPU 42 A / D converter 44 ROM 45 RAM 46 timer 47 512 dot line head 48 512 bit latch register 49 512 bit shift register 50 thermal line head unit 51 print data transmission signal line 52 latch signal line 53 strobe signal line 54 stepping motor unit 55 hold signal Line 56 Excitation signal line 60 Low battery interrupt generation circuit 61 Low battery interrupt signal line 62 Low battery interrupt Clear signal line 63 Thermistor 64 Thermistor with built-in battery 5

Claims (4)

[Claims] 1. A surface temperature of a battery is measured in a recording method of a thermal line printer, which uses a battery as a power source and performs thermal recording by a thermal line head having a plurality of heating elements arranged in a line direction orthogonal to a paper feeding direction. Then, the number of the heating elements to be heated at the same time is determined in correspondence with the measured level of the battery surface temperature. 2. The recording method for a thermal line printer according to claim 1, wherein a plurality of print modes are realized by changing the number of the heating elements to be simultaneously heated. 3. A thermal line printer for performing thermal recording using a battery as a power source, and a thermal line head having a plurality of heating elements arranged in a line direction orthogonal to the paper feed direction, and means for measuring the surface temperature of the battery. And a means for determining the number of the heating elements to be simultaneously heated in correspondence with the measured high or low of the battery surface temperature. 4. The thermal line printer according to claim 3, wherein a plurality of print modes are executed by changing the number of the heating elements to be heated at the same time.