JP2001310494A - Line thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a difference from appearing between print densities when the heating elements in respective blocks are driven even under chopper control of a time sharing pulse. SOLUTION: A line thermal head having a large number of heating elements arranged on a line is provided, a drive control circuit for driving the heating elements selectively by conducting the heating elements divided into a plurality of blocks selectively in units of block is provided, a conduction pulse for the heating elements is time shared and chopper control is performed by further time sharing the time shared conduction pulse such that the period between blocks is changed for each line. When chopper control is performed by further time sharing the time shared conduction pulse, the period of chopper control is changed between blocks for each line, number of pulses being time shared by chopper control is made uniform, and no difference appear between print densities when the heating elements in respective blocks are driven.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line thermal printer in which a heating element arranged on a line is energized and heated to form an image.

[0002]

2. Description of the Related Art In a conventional line thermal printer, an image is generally formed by printing in a main scanning direction by a line thermal head and printing in a sub-scanning direction by conveying a sheet in a direction perpendicular to this direction. ing. In such a line thermal printer, a heating element arranged on a line in a line thermal head is energized and heated, and when an ink ribbon is used, the ink of the ink ribbon is melted or sublimated and transferred to transfer paper, When thermal paper is used as the transfer paper, dots are formed on the transfer paper by the thermal coloring of the thermal paper.

Here, in order to control the energization of the heating elements of the line thermal head, generally, a print pulse signal and a strobe pulse signal based on print data are input to an AND gate, and the print pulse signal and the strobe pulse signal are input to the AND gate. This is performed by turning on a switching circuit that controls the energization of the heating element in accordance with an output signal from the AND gate that calculates the logical sum of

FIGS. 5 to 8 are timing charts of strobe pulses for explaining various types of energization control for the heating elements of the line thermal head. The control common to FIGS. 5 to 8 is that each heating element of the line thermal head is divided into two blocks, a left block and a right block, to generate a strobe pulse. That is, when simultaneously driving all the heating elements for which the print pulse signal is generated, large power is required at one time depending on the number of heating elements to be driven. For this reason, disadvantages such as the necessity of a large-capacity power supply and an increase in the size of the apparatus occur. In the example shown in FIGS. 5 to 8, each heating element of the line thermal head is divided into a left block and a right block. The heating elements of the left block and the right block are alternately driven during the printing cycle of one line. Specifically, during a one-line printing cycle, a strobe pulse for driving the heating element of the left block and a strobe pulse for driving the heating element of the right block are alternately input to the AND gate, whereby the left gate is driven. The alternate drive of the heating element of the block and the right block is realized.

FIG. 5 is a timing chart showing strobe pulses for explaining the basic control of such divisional driving of the heating elements. In this example, the switching circuit is turned on by the logical sum of the L strobe pulse signal and the print pulse signal. This is shown in FIGS.
The same applies to the drive control of the heating element using the strobe pulse illustrated in FIG.

However, when the heating elements are driven using strobe pulses as shown in FIG. 5, the heating state of the heating elements located at the boundary between the left block and the right block differs in each block. That is, the heating temperature of the heating element that is generating heat adjacent to the heating element that is not generating heat is lower than the heating temperature of the other heating elements that are generating heat due to the influence of the adjacent heating element that is cold. For this reason, depending on the print content, there is a problem that the print density at the division boundary between the left block and the right block becomes light, and a white streak may occur at that portion.

FIG. 6 shows an example in which time-division driving is further performed within a one-line printing cycle on the assumption that the heating elements of the left block and the right block are alternately driven. That is,
The strobe pulse for the left block and the strobe pulse for the right block are each time-divided by ta time. This solves the problem that occurs when the heating element is driven using the strobe pulse as shown in FIG. 5, that is, the problem that white stripes occur at the division boundary between the left block and the right block.

However, when the line thermal head is actually driven, thermal history control is often performed to improve the printing quality. Therefore, as shown in FIG. 7, the to-be-timed ta time within the one-line printing cycle has a gradation property,
Conventionally, energization control for performing heat history control has been performed. In the example shown in FIG. 7, gradation is given to the ta time in the range from the longest t1 time to the shortest t7 time.

[0009] Further, as shown in FIG.
A chopper control for further dividing the time a may be performed. This is because, as shown in FIG. 7, when the gradation time is given to the ta time in the range from the time t1 to the time t7, the continuous energization time of the heating element at the longest time t1 becomes longer. Shorten the life of the head,
Alternatively, the control is performed in consideration of damaging the ink ribbon and generating wrinkles. In other words, by performing the chopper control, the continuous energization time of the heating element is shortened at the time t'1 which is the longest energization time in the time-division driving, thereby preventing the life of the line thermal head from being shortened and the ink ribbon from being damaged. Things.

[0010]

However, in the chopper control accompanying the heat history control as exemplified in FIG. 8, the length of the strobe pulse to be chopper-controlled is not specified.
In other words, whether the strobe pulse at time t1 is chopper-controlled, whether the strobe pulse at time t2 is chopper-controlled, or whether the strobe pulse at other times is chopper-controlled depends on the degree of thermal history control. I do. For this reason, the number of time-division pulses to be chopper-controlled is not specified, and the number of time-division pulses may differ between the left block and the right block. For this reason, there is a problem that a density difference is generated between the print density by the heat drive of the heating element of the left block and the print density by the heat drive of the heat element of the right block depending on the print content.

When driving the heating elements of the line thermal head using strobe pulses as shown in FIGS. 7 and 8, driving the heating elements using strobe pulses as shown in FIG. The same problem as described above, that is, a problem arises in that the print density at the division boundary between the left block and the right block is reduced, and white stripes are generated at that portion. This is because the time-divided longest strobe pulse (t1 in FIG. 7 and t′1 in FIG. 8) is generated as the last pulse in the time-division pulse train in each block. Such a problem is more remarkable when performing chopper control as illustrated in FIG. This is because the time t′1 of the longest pulse among the time-divided strobe pulses becomes longer than t1 when the chopper control is not performed in accordance with the chopper control.

It is an object of the present invention to prevent a density difference from occurring between print densities due to heat generation driving of heat generation elements of each block even when chopper control is performed on time-division pulses.

An object of the present invention is to prevent the density at the division boundary of each block from becoming light even when chopper control is performed on the time division pulse.

[0014]

According to a first aspect of the present invention, there is provided a line thermal printer comprising: a line thermal head having a plurality of heating elements arranged on a line; and a heating element divided into a plurality of blocks. A drive control circuit that selectively heats the heating element by selectively energizing each block unit, and a time-sharing such that an energizing pulse for energizing the heating element has an alternating cycle between the blocks. Means for performing chopper control by further time-dividing the time-divided energizing pulses so that the cycle between the blocks is switched every n lines. Therefore, when performing the chopper control by further time-dividing the time-divided energizing pulses, the cycle of the chopper control is switched between the blocks every n lines. As a result, the number of pulses that are time-divided by the chopper control is made uniform in each block, so that there is no density difference between print densities caused by the driving of the heating elements in each block.

According to a second aspect of the present invention, a line thermal head having a plurality of heating elements arranged on a line, and the heating elements divided into a plurality of blocks are selected for each block. A drive control circuit for selectively heating the heating element by energizing the heating element; a means for time-sharing an energizing pulse for energizing the heating element so as to have an alternating cycle between blocks; and Means for performing chopper control by further time-dividing the time-divided energizing pulse so that an alternating cycle is formed between them. Therefore, when performing the chopper control by further time-dividing the time-divided energizing pulse,
The energizing pulse time-divided by the chopper control has an alternating cycle between the blocks. Therefore, a decrease in the temperature of the heating element that is not generating heat during chopper control is suppressed, whereby the heating temperature of the heating element that is adjacent to the heating element that is not generating heat becomes lower than the other heating elements that are generating heat. The temperature does not decrease with respect to the heating temperature of the element. Therefore, the problem that the print density at the division boundary portion between the left block and the right block becomes low and a white streak occurs at that portion is solved.

According to a third aspect of the present invention, there is provided a line thermal printer having a plurality of heating elements arranged on a line and selecting the heating elements divided into a plurality of blocks for each block. A drive control circuit for selectively heating the heating element by energizing the heating element; a means for time-sharing an energizing pulse for energizing the heating element so as to have an alternating cycle between blocks; and Means for performing chopper control by further time-dividing the time-divided energizing pulse so that the cycle between the blocks is alternated every n lines. Therefore, when performing the chopper control by further time-dividing the time-divided energizing pulses, the cycle of the chopper control is switched between the blocks every n lines. As a result, the number of pulses that are time-divided by the chopper control is made uniform in each block, so that there is no density difference between print densities caused by the driving of the heating elements in each block. Further, when performing the chopper control by further time-dividing the time-divided energizing pulse, the energizing pulse time-divided by the chopper control has an alternating cycle between the blocks.
Therefore, a decrease in the temperature of the heating element that is not generating heat during chopper control is suppressed, whereby the heating temperature of the heating element that is adjacent to the heating element that is not generating heat becomes lower than the other heating elements that are generating heat. The temperature does not decrease with respect to the heating temperature of the element. Therefore, the problem that the print density at the division boundary portion between the left block and the right block becomes low and a white streak occurs at that portion is solved.

According to a fourth aspect of the present invention, in the line thermal printer according to the first, second, or third aspect, the means for time-dividing the energizing pulse is configured such that the energizing pulse is time-divided by changing the energizing pulse width to control the chopper. Means performs chopper control on at least the last pulse divided in time. Therefore, heat history control is possible. Further, since the chopper control is performed on at least the last pulse that is the longest pulse among the time-divided pulses, the operation of the invention according to claim 1, 2 or 3 is more effectively achieved. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. This embodiment is an example of application to a label printer.

FIG. 1 is a side view thereof. Housing 1
A paper holding unit 3 for holding the continuous paper 2 is provided outside the printer. The label printer 4 according to the present embodiment draws the continuous paper 2 held by the paper holding unit 3 into the housing 1 and prints the continuous paper 2 by the printing mechanism 5 housed inside the housing 1. Print out the specified items. In the present embodiment, as the continuous paper 2, a label paper or a tag paper in the form of a roll paper wound in a roll shape is used.

Inside the housing 1, there is formed a paper passage 8 extending from the paper supply port 6 to the paper discharge port 7, and is rotatably rolled by a pair of rotatable paper holding rollers 9 in the paper holding section 3. The held continuous paper 2 is drawn into the paper passage path 8 from the paper feed port 6 and guided to be discharged from the paper discharge port 7.

The printing mechanism 5 is provided in the paper passing path 8 for guiding the continuous paper 2 in this manner. The printing mechanism 5 includes a rotatable platen roller 11 that is rotatably driven by a stepping motor 10 (see FIG. 2), and a thermal head 12 as a line thermal head that comes into contact with the platen roller 11 via the paper passage 8. The main body is formed. The thermal head 12 is held by a head holding plate 14 rotatably supported by a support shaft 13 arranged in parallel with the platen roller 11.
Is a thermal head 12 by a spring (not shown).
Are urged in a direction pressed against the platen roller 11.

Here, the printing mechanism 5 issues the printed continuous form 2 as the label printer 4 of the present embodiment.
Then, in the paper passing path 8, a peeling issue in which the label is peeled off from the backing sheet using the label peeling plate 15 arranged immediately downstream of the printing mechanism 5, and a continuous issue in which the continuous paper 2 is issued as it is, And issue a label by cutting the backing sheet for each label using the cutter unit 16,
Alternatively, it is possible to select three types of issuance modes, namely, cut issuance in which continuous paper is cut in predetermined units and issued.
However, the description of the structure and control for that will be omitted.

FIG. 2 is a block diagram of the electrical connection of each part. The components such as the stepping motor 10 for rotating and driving the platen roller 11 and the thermal head 12
Microcomputer 1 constituted by PU17 and the like
8 is driven and controlled. That is, the CPU 17 that executes various arithmetic processes and controls each unit intensively is provided.
An RO for fixedly storing fixed data is stored in the CPU 17.
M19 and RAM 20 for rewritably storing variable data
Are connected via a system bus 21. ROM
A control program is stored in 19, and the microcomputer 18 executes various processes according to the control program stored in the ROM 19, using the RAM 20 as a work area.

In this embodiment, the motor driver 22 for controlling the driving of the stepping motor 10 for rotating and driving the platen roller 11 is a component that is driven and controlled by the microcomputer 18 for the printing operation in the printing mechanism 5. And a head driver 23 as a drive control circuit for controlling the drive of the thermal head 12. The motor driver 22 and the head driver 23 are connected to the CPU 17 via the system bus 21.
It is connected to the.

Further, the label printer 4 of the present embodiment
Adopts a line type printing method, so that the thermal head 12 has a large number of heating elements 24 provided on the line.
(See FIG. 3), printing in the main scanning direction is performed, and printing in the sub-scanning direction is performed by movement of the continuous paper 2 with respect to the thermal head 12 caused by conveyance of the continuous paper 2. Therefore, it is necessary to detect the transport timing of the continuous paper 2 and the like for printing in the sub-scanning direction. In this embodiment, the transmission type sensor 25 and the reflection type sensor 2 are used for such detection.
The sensor section 27 including the two types of sensors 6 and 6
Is located inside. The transmission sensor 25 and the reflection sensor 26 are connected to the system bus 21 via an I / O port 28. Here, the transmission type sensor 25
Is a sensor for detecting a mount portion between labels in the label paper used as the continuous paper 2, and the reflection type sensor 26 is a sensor for detecting a mark for position detection printed on the tag paper.

Further, the label printer 4 of the present embodiment
Then, the print data transferred from the external device is fetched via the interface 29, and this interface 2
9 is converted into image data and is developed in the image memory 30. Therefore, the interface 29 and the image memory 30 are also connected to the system bus 2.
1 is connected to the CPU 17.

FIG. 3 is a circuit diagram of the head driver 23. In the head driver 23, 24V from a power supply circuit (not shown) is supplied to a large number of thermal heads 12,
It is configured to be able to selectively apply to 560 heating elements 24. As a structure for selectively applying a voltage to the heating element 24, the head driver 23 includes:
A plurality of transistors 31 functioning as switching transistors are provided corresponding to the respective heating elements 24.
An AND gate 32 is connected to a base for controlling ON / OFF of each transistor 31, and an output signal from the AND gate 32 is input.

Here, on the input side of the AND gate 32,
The configuration is such that the strobe signal STB and the latch signal are input.

That is, a D-type flip-flop circuit (FF circuit) 33 that operates using the input clock signal CLK as a reference clock is provided.
Is configured such that print data developed in the image memory 30 is serially input for each line of the thermal head 12. The print data for one line serially input to the FF circuit 33 is configured to be output to the latch circuit 34 in parallel. Each of the latch circuits 34 is configured to input a latch signal to one input terminal of the AND gate 32 in response to the input of the latch signal LATCH.

On the other hand, a strobe signal STB input to the other input terminal of the AND gate 32 is generated by the microcomputer 18 and input to the AND gate 32 under the control of the CPU 17. Two types of such strobe signals STB, STB1 and STB2, are generated, and the strobe pulse STB is supplied to 1280 heating elements 24 in the left block LB of the thermal head 12.
1 is commonly assigned and 128 in the right block RB.
The strobe pulse STB2 is commonly assigned to the zero heating elements 24.

Next, the operation will be described. First, basic control performed by the head driver 23 for a printing operation will be described. Under the control of the CPU 17, the print data developed in the image memory 30 becomes F
The data is serially transferred to the F circuit 33. The print data serially transferred to the FF circuit 33 is transferred from the FF circuit 33 to the latch circuit 34 in parallel, and is latch-set. In this state, when the latch signal LATCH is collectively input to the latch circuit 34, the latch circuit 34 that has been latch-set based on the print data outputs the latch signal to the corresponding AND gate 32. At this time, the CPU 17 outputs a strobe pulse STB to the AND gate 32 in synchronization with the operation of the head driver 23. As a result, an output signal is generated from the AND gate 32 and output to the base of the transistor 31. Thus, the voltage is applied to the corresponding heating element 24, and the heating element 24 is driven to generate heat.

FIG. 4 is a timing chart illustrating the strobe pulse STB. In the present embodiment, the divided drive control, the thermal history control, and the chopper control are executed by the strobe pulse STB. The strobe pulse STB is indicated by L.

"Division drive control" refers to a control method in which the heating elements 24 of the thermal head 12 are divided into two blocks, and the driving cycles are shifted to drive the heating elements 24. In the case of the present embodiment, the driving control of the heating element 24 of the left block LB is performed by the strobe pulse STB1, and the driving control of the heating element 24 of the right block RB is performed by the strobe pulse STB2. And
As shown in FIG. 4, the strobe pulse STB1 and the strobe pulse STB2 are controlled by the CPU 17 so as to have an alternate cycle in which the cycle is shifted in both odd and even lines. For example, in an odd line, the left block L
B strobe pulse STB1 for heating element 24
Is a period of time t7, a pause of time t7, a period of time t6, and a strobe pulse STB being continuous. On the other hand, the strobe pulse STB1 for the heating element 24 of the right block RB
Is a pause at time t7, a pause at time t7, a pause at time t6, t6
The time and the strobe pulse STB are continuous.

"Heat history control" refers to each heating element 2
4 is a control for defining the current energization pulse width with reference to the past heating drive. In the case of the present embodiment, the width of the energizing pulse, that is, the width of the strobe pulse STB
The thermal history control is performed by variably controlling the width of the strobe pulse STB which is divided and driven. In the example shown in FIG.
Although the pulse width of the strobe pulse STB at the time of 6 hours and t7 is illustrated, according to the thermal history control, such a pulse width of the strobe pulse STB is appropriately combined with another pulse width.

"Chopper control" is a time-divided energizing pulse, that is, strobe pulses STB1 and STB1.
This means control for further time-sharing TB2. In the example shown in FIG. 4, the strobe pulse STB at time t′1 is 16 μm.
The pulse width is further divided by a period of s to 8 μs. This is chopper control.

The split drive control, heat history control,
The operation and effect of the chopper control are as described in the section of the related art, and the description thereof will be omitted.

Here, the label printer 4 of the present embodiment
The microcomputer 18 includes a control for optimizing the number of strobe pulses STB and a chopper-controlled strobe pulse S in connection with chopper control.
And control for optimizing the relationship between TB1 and STB2.

That is, the CPU 17 executes a process of further time-dividing the strobe pulse STB related to the chopper control so that the cycle between the blocks LB and RB is switched for each line composed of the odd line and the even line. Therefore, the time-divided strobe pulse STB
Is further time-divided to perform the chopper control, the cycle of the chopper control is switched between the blocks LB and RB for each line. In the example shown in FIG. 4, in the odd-numbered line shown in FIG.
Is controlled so that the strobe pulse STB rises, while the strobe pulse STB of 8 μs in the order of the right block RB to the left block LB during the time t′1 which is the chopper control section in the even line shown in FIG. ST
B is controlled to rise. As a result, when viewed in units of a plurality of lines, the number of pulses time-divided by the chopper control is made uniform in each block LB, RB, and the density between print densities of the heating elements 24 in each block LB, RB is driven by heat generation. No difference is made.

Further, the CPU 17 determines that the strobe pulses STB1 and STB1, which are energization pulses time-divided so as to have an alternate period between the left block LB and the right block RB, are provided.
2 is further time-divided. That is, the CPU 17 generates the strobe pulse STB of the left and right blocks LB and RB within the time t′1. As a result, a decrease in the temperature of the heating element 24 that is not generating heat during chopper control is suppressed, and the heating temperature of the heating element 24 that is heating adjacent to the heating element 24 that is not generating heat is different from the other heating elements that are generating heat. The temperature does not decrease with respect to the heating temperature of the element 24. Therefore, the left block LB
This solves the problem that the print density at the division boundary between the image and the right block RB is reduced, and white stripes are generated at that portion.

In addition, in the present embodiment, the chopper control of the strobe pulse STB is performed in the time-divided final pulse portion having the longest pulse width. For this reason, it is executed by the CPU 17 in association with the chopper control.
Control for optimizing the number of strobe pulses STB, and chopper-controlled strobe pulses STB1 and STB1
The effect of control for optimizing the relationship with TB2 appears more remarkably.

In this embodiment, a strobe pulse STB for driving the heating element 24 is supplied to the left block L
Although the strobe pulse STB1 for B and the strobe pulse STB2 for right block RB are divided into two, the number of division may be three or more for division drive control.

The cycle of the chopper control is changed
The present invention is not limited to the odd-numbered line and the even-numbered line as in this embodiment, but may be two or more lines.

Further, in the present embodiment, an example is shown in which the energizing pulse is a strobe pulse STB, but the present invention is not limited to this. Moreover, the strobe pulse S
The pulse width control and cycle control of the TB may be performed not by software control using the CPU 17 but by hardware control of a digital circuit or the like, or may be hybrid control of software control and hardware control.

[0044]

According to the first aspect of the present invention, there is provided a line thermal printer including a line thermal head having a plurality of heating elements arranged on a line, and a plurality of heating elements divided into a plurality of blocks. A drive control circuit that selectively heats the heating element by selectively energizing the heating element, and a time-sharing means for energizing pulses for energizing the heating element so as to have an alternating cycle between blocks, means for performing chopper control by further time-dividing the time-divided energizing pulses so that the cycle between the blocks is switched every n lines. Therefore, it is possible to prevent a density difference from occurring between print densities due to the heat driving of the heat generating elements of each block, Thereby improving the character quality.

According to a second aspect of the present invention, there is provided a line thermal printer having a plurality of heating elements arranged on a line and selecting the heating elements divided into a plurality of blocks for each block. A drive control circuit for selectively heating the heating element by energizing the heating element; a means for time-sharing an energizing pulse for energizing the heating element so as to have an alternating cycle between blocks; and Means for further performing time division on the time-divided energizing pulse so as to form an alternating cycle between the blocks, so that the heating temperature of the heating element under chopper control is made uniform among the blocks. This solves the problem that the print density at the division boundary between the left block and the right block becomes low, and white streaks occur at that part. It can be, thereby improving the printing quality.

According to a third aspect of the present invention, a line thermal head having a plurality of heating elements arranged on a line, and the heating elements divided into a plurality of blocks are selected for each block. A drive control circuit for selectively heating the heating element by energizing the heating element; a means for time-sharing an energizing pulse for energizing the heating element so as to have an alternating cycle between blocks; and Means for performing chopper control by further time-sharing the time-divided energizing pulse so that the cycle between each block is switched every n lines. The number of pulses for each block can be made uniform in each block. It can ensure that no, this makes it possible to improve the printing quality. In addition, the heating temperature of the heating element during chopper control can be made uniform between the blocks, so that the print density at the division boundary between the left block and the right block becomes thin, and white streaks occur in that portion. Problem can be solved, and this can also improve the print quality.

According to a fourth aspect of the present invention, in the line thermal printer according to the first, second, or third aspect, the means for time-dividing the energizing pulse is configured such that the energizing pulse is time-divided by varying the energizing pulse width to control the chopper. Means performs chopper control on at least the last pulse that is time-divided, so that the chopper control can be performed on at least the longest pulse of the time-divided pulse. And therefore claim 1,
The effect of the invention described in 2 or 3 can be more effectively produced.

[Brief description of the drawings]

FIG. 1 is a side view of a line thermal printer showing one embodiment of the present invention.

FIG. 2 is a block diagram of electrical connection of each unit.

FIG. 3 is a circuit diagram of a drive control circuit (head driver).

FIG. 4 is a timing chart illustrating a strobe pulse.

FIG. 5 is a timing chart showing an example of a conventional strobe pulse for block division driving.

FIG. 6 is a timing chart showing an example of a conventional strobe pulse for time division driving.

FIG. 7 is a timing chart showing an example of a conventional strobe pulse for thermal history control.

FIG. 8 is a timing chart showing an example of a conventional strobe pulse for chopper control.

[Explanation of symbols]

 12 line thermal head (thermal head) 23 drive control circuit (head driver) 24 heating element STB energizing pulse (strobe pulse)

Claims (4)

[Claims] 1. A line thermal head having a number of heating elements arranged on a line, and selectively applying a current to the heating elements divided into a plurality of blocks in units of blocks, thereby energizing the heating elements. A drive control circuit for selectively generating heat, a means for time-sharing an energizing pulse for energizing the heat-generating element so as to have an alternating cycle between the blocks, and a cycle between the blocks is switched every n lines. To
Means for performing chopper control by further time-dividing the time-divided energizing pulses. 2. A line thermal head having a large number of heating elements arranged on a line, and said heating elements are selectively energized to each of said heating elements divided into a plurality of blocks in units of blocks. A drive control circuit for selectively generating heat; a means for time-sharing an energizing pulse for energizing the heating element so as to have an alternating cycle between the blocks; Means for performing chopper control by further time-dividing the divided energizing pulses. 3. A line thermal head having a large number of heating elements arranged on a line, and selectively applying power to each of the heating elements divided into a plurality of blocks in units of blocks. A drive control circuit for selectively generating heat, a means for time-sharing an energizing pulse for energizing the heating element so as to have an alternating cycle between the blocks, an alternating cycle between the blocks, and an n-line Means for performing a chopper control by further time-dividing the time-divided energizing pulse so that the cycle between the blocks is switched. 4. The time-division means for energizing pulses is time-divided by varying energizing pulse widths, and the means for performing chopper control performs chopper control on at least the time-divided final pulse. Item 4. The line thermal printer according to item 1, 2 or 3.