JPH05529A - Thermal printer - Google Patents

Abstract

PURPOSE:To obtain a thermal printer which can drive at a voltage as low as the order of 5V to conduct printing at a high speed while preventing a printing failure resulting from a voltage drop by an internal impedance and an in-head loss by an in-head common conductor. CONSTITUTION:A thermal printer comprises a printing head 1 provided with a plurality of heating elements 2 divided into printing blocks 3a-3e by the predetermined number and a heating means 4 for electrically heating the heating elements 2 based on predetermined data per printing block 3a-3e. The heating means 4 is so constructed as to simultaneously heat the two or more printing blocks 3a-3e to color heat-sensitive paper 7 abutting on the heating elements 2 of the printing block 3.

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, and more particularly to a line thermal printer which is suitable for use in a field such as a handy terminal and is installed in a small portable device driven by a battery.

[0002]

2. Description of the Related Art In recent years, many so-called thermal printers have been developed which print by electrically heating a print head corresponding to characters and figures on a thermal paper which develops color when heat is sensed. Among these thermal printers, battery-powered thermal printers are roughly classified into two groups, such as low-voltage (about 5 V) serial thermal printers and high-voltage (about 12 V) line thermal printers. In general, a thermal printer operating at a low voltage has a low printing speed, and a thermal printer having a high printing speed requires a high voltage.

That is, in a small portable device such as a handy terminal, it is driven at a low voltage such as a battery drive of about 4.5 to 6.5 V or a single 5 V power source, and therefore, high speed operation is possible. Cannot be printed on. Therefore, for example, a line thermal printer that operates at a low voltage of about 5V is required.

On the other hand, the thermal paper used in this thermal printer is not limited to the normally used 1ply paper, but is, for example, a color that develops by feeling heat at different temperatures, that is, by giving different printing energy. There are various types, such as red and black paper, which changes in color, and 2ply paper that does not develop color when printing energy that is much larger than the normal printing energy that heats 1ply thermal paper is applied.

Therefore, in order to obtain good print quality on various types of thermal paper, a line thermal printer capable of changing the printing energy per unit area according to the thermal paper used is required. As a conventional thermal printer of this type, for example, there is a line thermal printer as shown in FIG.

The print head 1 of this line thermal printer has eight heating elements 2 of 320 dots per dot line.
It is composed of four print blocks 3a to 3d divided every 0 dots. In the above configuration, when printing on a predetermined thermal paper, first, the heating element 2 in the print block 3a is energized with a high voltage of, for example, about 12 V for a predetermined time based on the predetermined data, and then, as shown in FIG. As shown in (3), printing is performed at the thermal paper position corresponding to the printing block 3a (hatched portion), and then the paper is slightly fed.

Hereinafter, similarly, the printing blocks 3b, 3c, 3
The heating elements 2 in d are sequentially energized, and the printing blocks 3b,
Printing is performed at the thermal paper positions corresponding to 3c and 3d (hatched portion), and printing of one dot line is completed.

[0008]

However, in such a conventional line thermal printer, since a high voltage of about 12V is applied for a predetermined time, for example, 4.8V to 5.0V. When printing line by line with a low voltage, there is a problem that good printing quality or print density cannot be obtained because the printing energy is small, and as a result, printing cannot be performed at high speed. was there. This is because a small portable device, such as a handy terminal, needs to be driven at a low voltage such as being driven by a single power supply of about 4.8V.
This is because sufficient printing energy cannot be taken out at such a low voltage.

Further, there is a problem that high-speed printing cannot be performed by driving with a low voltage. That is, in order to obtain the required amount of heat generation at a low voltage, it is necessary to lower the resistance value and increase the current value, but generally the energy required for printing is However, epsilon: Energy V per unit area: applied voltage V _S: saturation voltage R: heating element resistance value t: Pulse Width S: represented by the heating element area, in order to increase the printing energy epsilon is
Whether the saturation voltage V _S is reduced, the heating element resistance value R is reduced, or the heating element area S is reduced,
The pulse width t has to be increased.

However, the resistance value R of the heat generating element is limited in terms of the material of the print head, and when the resistance value R of the heat generating element decreases, the current i flowing through the heat generating element 2 increases. Therefore, the saturation voltage V _S increases. The saturation voltage V _S becomes reactive energy and has no effect on the color development of the print. To explain this, the current i = (V−V _S ) / R, which is the current flowing through a single heating element, and the total current flowing through the actual print head 1 is

[0011]

[Equation 1]

[0012] That is, the saturation voltage V _S is the current i
And V _S = ai + b approximately. (Note that the saturation characteristic of the switching transistor actually causes a non-linear system.) Therefore, when the current i increases, the saturation voltage V _S increases and V−V _S decreases, so the printing energy ε decreases.

When a battery is used, the applied voltage V itself is the current i because the internal impedance exists.
A new problem arises, such as a voltage drop due to fluctuations depending on the print head, a loss in the head due to a common conductor in the head, and a print failure. For this reason, the optimum range of the resistance R of the heating element is naturally determined, and accordingly, the pulse width t has to be increased inevitably.

Since increasing the pulse width t generally increases the printing cycle, the printing speed becomes slow, and the pulse width T cannot be made too large in order to realize high-speed printing. Since reducing the pulse width generally shortens the printing cycle, the printing speed is increased, but the printing energy ε is reduced.

Therefore, according to the present invention, printing is performed at a high speed by driving at a low voltage of about 4.8 to 5 V, while preventing a printing failure due to a voltage drop due to internal impedance and a head loss due to a common conductor inside the head. One purpose is to provide a thermal printer and, for example, 4.8V
Another object of the present invention is to provide a line thermal printer capable of obtaining a good printing quality on various thermal papers while preventing the printing speed from being lowered even when driven at a low voltage of about 5.0V.

[0016]

In order to achieve the above object, the line thermal printer according to the present invention adopts the following basic technical constitution. That is, as a first aspect of the line thermal printer of the present invention, there is provided a line thermal printer which electrically heats a print head having a plurality of heating elements and causes the thermal paper in contact with the heating elements to develop color for printing. The line thermal printer includes a print head including a plurality of print block groups obtained by dividing the plurality of heat generating elements by a predetermined number, and electrically heating the heat generating elements based on predetermined data for each print block. A line thermal printer configured to simultaneously heat at least two print blocks selected from the print block group, and A second aspect is a line thermal printer in which a print head having a plurality of heating elements is electrically heated and a thermal paper in contact with the heating elements is colored to perform printing. The line thermal printer includes heating means for electrically heating the heating element on the print head based on predetermined data, and further, a plurality of print modes according to the type of the thermal paper and a print cycle. And an energization control unit that controls energization to the print head in a fixed state, the energization control unit determining the number of energizations to the print head based on the print mode, It is a line thermal printer configured to change printing energy per area.

The thermal printer is provided with a plurality of different printing modes, and the heating is performed based on the number of the printing blocks simultaneously heated by the heating means and the data in the printing blocks according to the printing modes. It may be configured to change the pattern of the heating element to be heated, and a printing rate determining means for determining the number of heating elements to be heated with respect to the total number of heating elements in the print block based on the data. When the number of heating elements to be heated by the heating means exceeds a predetermined number by the printing rate determination means, it is effective to configure the heating means to further divide the printing block to heat it. ..

[0018]

In the present invention, the heating means simultaneously heats the heating elements in the plurality of printing blocks, thereby printing on the thermal paper. That is, for example, printing is speeded up even when driven at a low voltage of about 4.8V to 5V. Further, when the number of heating elements in the print block to be heated by the heating means exceeds a predetermined number, the print block is further divided and heated by the heating means, so that the voltage drop due to the internal impedance and the head common Printing defects such as loss in the head due to the conductor are prevented.

Therefore, the print failure due to the voltage drop due to the internal impedance and the loss in the head due to the common conductor in the head is prevented, and printing is performed at high speed by driving at a low voltage of about 4.8V to 5V. Further, in the present invention,
The energization control means controls energization to the print head in a fixed printing cycle, and the number of energizations to the print head is determined based on a plurality of printing modes according to the type of thermal paper to print per unit area. Energy is changed.

Therefore, for example, 4.8V to 5.0V
Even when driven at a low voltage, the printing speed is prevented from lowering, and good printing quality can be obtained on various types of thermal paper.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples of the present invention will be described below with reference to the drawings. 1 to 11 are views showing an embodiment of the thermal printer according to the first aspect of the present invention. First, the configuration will be described.

As shown in FIG. 1, the print head 1 of the thermal printer of this embodiment comprises five printing blocks 3a to 3e in which a heating element 2 of 320 dots per dot line is divided into 64 dots. There is. In addition, 4 is a heating means and 5 is a printing rate determination means. Also, 6 is the second described later.
It is an energization control means used in the aspect.

The heating means 4 energizes the heating element 2 of each of the printing blocks 3a to 3e based on predetermined data, and the heating means 4 simultaneously heats according to a plurality of different printing modes described later. The number of blocks 3a to 3e,
The pattern of the heating element 2 to be heated in the print blocks 3a to 3e is changed. Each heating element used in the present invention is composed of a plurality of units U as illustrated in FIG.
1 to Un (four examples are shown in FIG. 2), and each unit heating element is individually and independently controlled to generate heat.

The printing rate measuring means 5 includes printing blocks 3a-
When the number of heating elements 2 to be heated with respect to the total number of heating elements 2 in 3e, that is, the printing rate is higher than a predetermined value,
The print blocks 3a to 3e to be heated by the heating means 4 are further divided and heated. Specifically, the number of batch print data is redacted to increase the print cycle.

Further, as described above, the energy required for printing is Therefore, in order to reduce the applied voltage V, it is necessary to reduce the resistance value R of the heating element or increase the pulse width t. Therefore, in the present embodiment, in consideration of these, in order to perform high-speed printing at a low voltage, the applied voltage V is set to 4.5 to
6.5V, heating element resistance value 45Ω ± 10%, heating element area S head resolution 6 lines / mm, 1PLY, W0.165mm × H0.165mm for label paper, W0.165mm × for 2PLY The height is set to 0.330 mm.

Further, in order to increase the pulse width t without sacrificing the printing speed, in this embodiment, the heating means 4 simultaneously heats the heating elements 2 in the plurality of printing blocks 3a to 3e. Here, the outline of the control system of the line thermal printer according to the present invention will be described with reference to FIG.

That is, the printing device of the line thermal printer according to the present invention is driven by the motor M to move the paper 7 or the like to be printed sheet in a predetermined direction at a predetermined speed and a predetermined pitch. And a print block 3a, 3b, 3c ... In which a plurality of heating elements 2 are arranged in series in parallel with the rotation axis direction of the sheet transfer means 8 in contact with the sheet transfer means 8. A print head 1 including a print block group 3 arranged in series, and a sheet transfer means control means 11 for controlling the sheet transfer means 8 and a print control for driving a print block of the print section. Block control means 12 is provided, and the sheet transfer means control means 11 and print block control means 12 store print data input instruction means 14 and predetermined print data. It is configured to be controlled by a central processing means (CPU) 13 connected to a print data memory means 10 composed of, for example, a ROM.

Next, the print data processing procedure of the line thermal printer according to the present invention will be described with reference to FIGS. 12 and 13. First, when predetermined print data to be printed is input to the print data instructing means 14, the data is received by the receiving buffer 15 in the central processing means (CPU) 13.
The data analysis means 16 analyzes the received data and separates it into a control code CD and a data D, transfers the control code CD to a flag register 17, and transfers the data D to the data block 18. To the code data buffer 18-2.

On the other hand, the control code CD is information for designating the type of mode such as high-speed printing mode, high-quality printing mode, double-density printing mode, and the flag register 17
Then, the flag and parameter setting processing is executed and the data is transferred to the modified data buffer 18-1 of the data block 18. After that, the information in the data buffer 18 is transferred to the code buffer 19 including a RAM or the like.

The code buffer 19 is a buffer (20-1, 20-2), (21-1, 21-2) for storing modification data and code data for each data.
.. (2n-1, 2n-2), and each transferred data is stored in each buffer. Next, the predetermined data to be printed stored in the code buffer 19 is transferred to the task table 22 as shown in FIG.

The task table 22 includes task units 22-1, 22-2, ... 22-n which individually store a plurality of tasks (task # 1 to task #N). Related task units 22-1, 22
2, ... 22-n include functions corresponding to the respective modified data corresponding to the above-mentioned high-speed printing mode, high-quality printing mode, double-density printing mode, etc., and the code buffer 19 One of the tasks is selected by discriminating the flag of the modified data possessed by each data transferred from the.

If the flag of the decoration data of the data 1 transferred from the code buffer 19 indicates the high speed print mode, it corresponds to the program for processing the high speed print mode. For example, the task unit 22-2 having the task # 2 to be executed is selected, and the code data of the data 1 is also selected at the same time.
-2.

Thereafter, the code data of the data 1 is read out from the character generation (CG) font table 24 in accordance with the font address of the code data, and the font data stored in the font address is read out from the task unit. 22-2, the read font data is processed by the task unit 22-2 according to the program of the modification flag of the task unit 22-2, the high speed print mode data is processed, and the result is stored in the image buffer. 25, and stores.

The image buffer 25 according to the present invention
Includes, for example, two image buffers 26 and 27, and the first image buffer 26 stores print data for one line to be printed now.
The first image buffer 26 is about to print 1
The print data for one line before the line is stored.

The image buffer in the present invention has 2
It is needless to say that the number of image buffers is not limited to a combination of three and a plurality of image buffers of three or more may be combined. In the printing operation of the present invention, for example, in the double density mode of characters, 32 dots are used.
16 dots can be adopted in the normal mode.

In the present invention, the print data for one line forming one dot is stored in one image buffer. Furthermore, in the present invention,
According to the print data stored in the image buffer, each heating element 2 of each print block is energized for printing at a predetermined timing.
The line is divided into a plurality of times for energization, and for example, one line is divided into five times for energization processing.

Therefore, since 32 dots are adopted in the double density mode, it is necessary to carry out energization processing of 160 times with 32 lines x 5 energization for printing one character, and in the normal mode. Uses 16 dots, so 16
It is necessary to energize 80 times by energizing the line x 5. or,
In the case where the present invention adopts the double density mode and the normal mode, the configuration of the heating element 2 in the present invention is four heating element units U1 to U as shown in FIG. 1 or FIG.
Preferably, it is composed of 4.

A specific example of the print processing procedure according to the present invention will be described below. The line thermal printer of the present embodiment is provided with four types of modes: a) high speed printing mode, b) high quality printing mode, c) reduction printing mode, d) double density printing mode, and a) high speed printing. The mode is a so-called 3-burn system in which the heating elements 2 in the three continuous printing blocks 3a to 3e are simultaneously heated by the heating means 4, and is 3 burns.
The number of dots targeted for batch printing increases. That is,
For the number of dots to be energized at the same time, perform data redact, Becomes

Therefore, when the printing rate becomes higher than the predetermined value by the printing rate judging means 5, the number of batch printing data is redacted and the printing cycle is increased. The printing rate determining means 5 makes a determination in units of each of the printing blocks 3a to 3e, so that printing is performed without lowering the overall execution printing speed. Further, in the high speed print mode, the number of print dots in the horizontal direction is redacted by 50% in order to increase the print speed, and the relationship between the print data and the actual print is as shown in FIG. 2 pixels in the vertical direction in a 2 × 2 matrix are printed with respect to 1 pixel data as shown in FIG. 2, and in the image print mode, as shown in FIG. 2 pixels in the diagonal direction in the 2 × 2 matrix are printed.

The timing of energization in the present invention is the fifth.
As shown in the figure, T (α, β), T (α, β)
Of α indicates the α-th pulse, β indicates the printing block of the β-th group, and * indicates energization of the immediately preceding dot line. That is, in the present invention, an example of performing the energization process for one line 5 five times when performing the printing process for one dot line 1 is shown. T-1 to T-5 in FIG. 1
The line 1 is divided into 5 times, and the number of the block to be energized at the time of the first pulse T-1 is designated, and the number of the block to be energized at the time of the second pulse T-2 is designated. The same applies to T-3 to T-5 below. As described above, in the present invention,
As a specific example, two image buffers are used in combination, and therefore, FIG. 5 therefore corresponds to the first image buffer 26 storing the print data to be printed on the line l now.
And a second image buffer 27 storing the print data being printed or being printed on the line l-1 which is one line before.

In the print processing operation of the present invention, the sheet 7 to be printed is driven by the motor M based on the control signal from the sheet transfer control means 11 after one energization operation for one line 1 is completed. The sheet 7 is configured to be moved by a minute distance by rotating it by a minute angle. To explain the energization timing in FIG. 3, first, when the first energization pulse T-1 is generated, the block 3a of the first image buffer 26 and the second image buffer 27 are
By energizing the blocks 3d and 3e in the above, each heating element 2 included in each block is individually heated based on the print data stored in each block.

Then, after the sheet 7 is transported by a predetermined minute interval, when the second energizing pulse T-2 is generated, the first
Blocks 3a and 3b of the image buffer 26 and the second
When the block 3e in the image buffer 27 is energized, each heating element 2 included in each block is individually heated based on the print data stored in each block.

Similarly, when the second energizing pulse T-3 is generated, the blocks 3a of the first image buffer 26,
By energizing 3b and 3c, each heating element 2 included in each block is individually heated based on the print data stored in each block. That is, in the high-speed printing mode in this example, in the energization process for one print line, three printing blocks among a plurality of printing blocks (five in this example) are energized at the same time. Since the three-burn system for processing is adopted, high speed printing is realized.

(B) In the high-quality printing mode, the heating element 2 in the two continuous printing blocks 3a to 3e is simultaneously heated by the heating means 4, that is, the so-called 2-burn method is adopted, and printing is performed with 2 burns. Simultaneous energization is performed in the adjacent print blocks between the blocks 3a to 3e. Further, since the high quality printing is performed, the printing rate is doubled as compared with the high speed printing mode. That is, the number of dots for simultaneous energization is That is, about 30% higher than that of the high-speed printing mode, and the overall printing speed is lower than that of the high-speed printing mode.

Since the high-quality mode corresponds to printing on 2PLY paper or the like and the number of print dots is not redacted, the relationship between the print data and the actual print is shown in FIG. 6 for both the character print mode and the image print mode. As shown in, all pixels in the 2 × 2 matrix are printed for one pixel of data. The timing of energization is shown by T (α, β) as shown in FIG. 5, and α of T (α, β) is the αth
The second pulse, β, indicates the printing block of the β-th group, and * indicates energization of the immediately preceding dot line.

The description of FIG. 5 is the same as that of FIG. 6 except that the print blocks that are energized when one energization pulse is generated are two adjacent print blocks.
Detailed description is omitted. The reason why the printing speed is increased by adopting the multiple burn method as in the present invention is as follows. That is, as shown in FIG. 17A, for example, assuming a head having 320 dots in one dot line and divided into 5 blocks of 64 dots, in the conventional method, in units of 1 block. The method of driving in sequence is adopted. In this method, the coloring energy for the paper must be supplied from the heating element by one energization. However, as shown in FIG. 17B, in the method of the present invention, the width of the reference energization time is halved with respect to the above method, and a plurality of adjacent blocks are energized at once. In this method, printing is completed in half the time compared with the conventional method.

Further, since the heat generated by the electric heating element decreases exponentially, the coloring energy tends to increase as the printing cycle increases. When the speed is increased by this method, the printing cycle is shortened, so that there is a synergistic effect that the heat storage effect is used to enable efficient driving. Next, the difference between the printing method according to the present invention and the conventional printing method is shown in FIG.
5 and FIG.

FIGS. 15A and 15B show an example of the conventional printing method. One dot line is composed of 320 dots, and 64 dots are included in one block. 5
Although it is the same as the configuration of the present invention in that it is composed of individual blocks, the conventional method of FIG. 15A is the same because only one block is energized in one energizing pulse. Even if the next energization pulse arrives in the block and energization processing is performed, there is a problem that a gap or gap is generated between the previous energization pulse (6th previous pulse) and the print data printed. However, there is a problem that a large amount of load is required for one energization.

In the conventional example shown in FIG. 15 (B), one energizing pulse simultaneously energizes three consecutive blocks, but the other energizing pulses energize the remaining printing blocks individually. As shown, even in such a specific example, there occurs a problem that a gap or a gap occurs between the print data printed at the time of the previous energization pulse generation and the data printed by the current energization. is doing.

However, in the present invention, FIG.
As shown in (A) and FIG. 16 (B), in both the 2-burn system and the 3-burn system, a plurality of print blocks surrounded by thick lines in the drawing are one. Since the energization pulse is energized at the same time, the same print data is printed multiple times on the printing sheet, with some deviations in the print data. Since the density can be reduced, it contributes to the improvement of the printing speed.

C) The reduced print mode is a mode for increasing the number of print digits in one line as compared with the high speed print mode. The relationship between print data and actual print is as shown in FIG. 3 pixels are printed for 2 pixel data, and the relationship between the print data a, b and the reduced print data α, β, γ in FIG. 6 is based on the principle shown in Table 1. It will be exchanged based on the original.

[0052]

[Table 1]

The timing of energization is set to be the same as that in the high quality print mode. d) Double density printing mode is 3
This is a mode in which the number of print data is 20 dots / line, and the relationship between print data and actual print is that one pixel is printed for one pixel data as shown in FIG. This is a mode in which it is possible to print barcodes and the like because high-density printing is possible.

The timing of energization is set to be the same as that in the high-quality print mode as in the reduction print mode. As described above, optimum printing is performed according to each application by the four operation modes, and the print rate determination means 5 reduces the influence of the voltage drop due to the internal impedance of the battery, thereby stabilizing the print quality.

Using the multiple burn method according to the present invention
FIG. 14 shows the principle that the print quality, that is, the density is improved by the
Shown in. That is, the energization timing chart of FIG.
(TMG) 3rd burn for the first print block
Energization pulse F using the formula₁~ F ₃Energized at
Processing is performed (see FIG. 14B). On the other hand, the conventional method smells
For one print block N, one line corresponds to 1
Since the energization process is performed only once, the shaded area in FIG.
Only the print density distribution of print data as shown in the part can be obtained.
There is a blank area between adjacent print data because there is no
Therefore, the present invention has the drawback that the concentration may decrease.
Then, the same print block N should be energized three times in a row.
Also, since the printing sheet moves slightly at each energization
The print density distribution as shown in FIG. 14 (D) can be obtained.
And the density will appear darker.

Next, the thermal head used in the present invention
The equivalent circuit is shown in FIG. R in the figure₀~ R₆₃Is a heating element
Anti, r₀~ R₆₃Is the lead resistance, R_cIs the common conductor resistance, i
₀~ I₆₃Is the current flowing through the heating element resistance and lead resistance
(Hereinafter referred to as heat generation lead current), V_R0~ V_R63Is fever
Voltage applied to body resistance (hereinafter referred to as heating element voltage), V_r0
~ V_r63Is the voltage applied to the lead resistance (hereinafter, read voltage
Say), V_cIs the voltage across the common conductor resistance (hereinafter
Common voltage), Σi is the common conductor resistance R_cCurrent flowing through
(Hereinafter referred to as common current), and the heat generation lead current i₀
~ I ₆₃Is the total.

That is, the heating element voltage V _RO and the lead voltage V
_{The ro} and the common voltage V _c are represented by V _RO = i ₀ · R ₀ V _r0 = i ₀ · r ₀ V _c = A _(i) · Σi.

A _(i) is a variable due to the influence of the non-linear portion, the internal transistor Tr portion, etc., and A _(i) · Σi
Is correlated with the number of energized dots in 64 dots of the heating element 2 of one printing block 3a to 3e. Therefore, V _c also becomes non-linear. As shown in FIG. 8, the common conductor resistance R _c is non-linear, the value of the common conductor resistance R _c is changed by energization heater number in one printing block 3 a to 3 e.

Further, the influence on the energy ε is extremely large because the heating element resistance R ₀ is small. this is,
When the value of the heating element resistance R ₀ is sufficiently large, the lead resistance r
_Since the value of ₀ is extremely small, the ratio to the whole resistance is small and the influence is small. However, when the value of the heating element resistance R ₀ is small, the ratio of even a small value of the lead resistance r _{0 to} the whole resistance is large. This is because it will become a problem and the impact will increase.

Now, let us consider a case where the heating elements 2 for n dots are energized. (However, when the same print is locked, the maximum 64
Since it is a dot, 0 <n ≦ 64) From i ₀ · R ₀ + i ₀ · r ₀ + V _c = V, the voltage applied to the heating element 2 is i ₀ · R ₀ = V−V _c −i ₀ · r ₀ Therefore, ε = i ₀ · R ₀ ² · T / S = (V−V _c −i ₀ · r ₀ ) R ₀ · T / S.

Here, unlike the case where the applied voltage V is a constant voltage, in the case of battery driving, the actual voltage V is the original voltage V _{D of the} battery−the internal battery impedance r _b · Σi due to the battery internal impedance. ε = (V _D −i ₀ · r ₀ −V _c −r _b · Σi) R ₀ · T / S = [V _D −i ₀ · r ₀ − (A _(i) + r _b ) Σi] R ₀ · It becomes T / S.

Since i ₀ · r ₀ is considered to be sufficiently small with respect to other values, the influence of the term of (A _(i) + r _b ) Σi is sufficiently large. In order to correct this, it is necessary to subdivide according to the printing rate to reduce the energy fluctuation. This automatic printing rate determination is performed by the printing rate determination means 5 in the high speed printing mode and the high quality printing mode.

In this case, the target number of dots is 96 dots (3 burns) in the high-speed printing mode, and 128 dots (2 burns) in the high-quality printing mode. When a certain ratio (for example, 75% in the high speed printing mode) is exceeded, the number of divisions of the heating element 2 in the printing blocks 3a to 3e is increased, so that the number of energized powers is reduced.

At this time, the subdivision reduces the printing speed and promotes energy (heat) diffusion from the print head. That is, as shown in FIG. 11, when the printing speed becomes slower, an excessive energy ε is required to obtain the same temperature. That is, if the printing speed is too fast, the pulse width T becomes small and sufficient energy cannot be obtained, while if the printing speed is too slow,
If the pulse width T is applied until the density becomes low and one dot is completely colored, a practical printing speed cannot be obtained.

Therefore, the relationship between the printing rate and the printing speed is tabulated as shown in FIG.
And by changing the setting values of printing speed and printing rate based on the table value according to the quality of the thermal paper used, etc.
Both stable printing quality and high speed can be achieved. As described above, in this embodiment, the heating elements in the plurality of printing blocks simultaneously heat and print on the thermal paper. That is, for example, printing can be speeded up even by driving at a low voltage of about 5V.

Further, when the number of heating elements in the print block to be heated by the heating means exceeds a predetermined number, the print block is further divided and heated by the heating means, so that the voltage drop due to the internal impedance and the head internal It is possible to prevent printing problems such as loss in the head due to the common conductor. Therefore, it is possible to prevent the print failure due to the voltage drop due to the internal impedance and the loss in the head due to the common conductor in the head, and it is possible to perform the printing at a high speed even by driving the low voltage around 5V.

In the above embodiment, a print head having a heating element and divided into five printing blocks of 64 dots and having a total of 320 dots is described as an example.
Not limited to this, it goes without saying that the total number of heating elements included in the print head, the number of divisions into print blocks, and the like are arbitrary according to the given device and purpose. Next, the configuration of the line thermal printer according to the second aspect of the present invention, which is configured to have a plurality of printing modes according to the type of thermal paper, will be described.

The basic configuration of this example is almost the same as the configuration of FIG. 1 for the line thermal printer according to the first aspect. However, in this example, the energization control means 6 shown in FIG. 3 is utilized. The energization control unit 6 in the present specific example controls energization of the heating unit 4 to the print head 1 in a state in which the printing cycle is fixed, that is, in a state in which the feeding of the thermal paper is stopped. The number of energizations to the print head 1 is determined based on a plurality of print modes according to the type. However, in this specific example, as shown in FIG. 3, the print head 1 is composed of a plurality of printing blocks 3a to 3e in which a predetermined number of heating elements 2 are collected and formed into blocks. The block does not have to be configured to be energized at the same time.

As described above, the energy required for printing is As described above, the pulse width t is set small under various conditions as described above, but the printing energy ε is set large by energizing the power a plurality of times.

By the way, in this embodiment, the applied voltage V is 4.8 V, the resistance value R of the heating element is 45 Ω ± 10%, the area S of the heating element is 6 head resolution / mm, 1 ply, W0 for label paper. 165mm × H0.165mm, 2ply W0.165mm × H0.165mm, or W0.165
mm × H 0.330 mm is set. This is substantially the same condition as that of the first aspect.

Since the printing speed is not sacrificed, in this embodiment, the heating means 4 is used to print a plurality of printing blocks 3a ...
Of course, the heating element 2 in 3e can be simultaneously heated. Next, the operation will be described. The line thermal printer of this embodiment is provided with two types of modes such as a) 1ply print mode and b) 2ply print mode, and the energization timings thereof are as shown in FIG.

In the figure, a of G _a ^b is a group and b is
Indicates energization timing, and a portion surrounded by a thick line frame indicates energization timing of the previous dot line. That is, for example, in the group of (G ₀ ⁰ , G ₁ ⁴ , G ₂ ³ , G ₃ ² , G ₄ ¹ ), the first energization of the group 0 of the current line,
5th energization of group 1, 4th energization of group 2, 3rd energization of group 3, 2nd energization of group 4
This means that the second energization is performed at the same time.

The number of times b is determined according to the capacity of the power supply. That is, a) In the 1ply printing mode, when the printing energy ε for one time is small as in 1ply thermal paper, for example, as shown in FIG.
The number of times of energization twice is determined and controlled. In addition, 0 in the figure
Means a non-energized state.

As shown in FIG. 19, when simultaneous energization is performed in two groups (two printing blocks), the number of dots to be energized increases depending on the data to be printed.
The print rate may increase. At that time, when the printing rate becomes higher than a predetermined value, the printing rate determining means 5 redacts the number of batch printing data, and increases the printing cycle t. However, in the printing rate determination means 5,
Since the determination is performed in units of the print blocks 3a to 3e, printing is performed without lowering the overall execution print speed.

B) In the 2ply printing mode, when higher printing energy ε is required as compared with 1ply thermal paper like 2ply thermal paper, the speed is increased by using 2 dot lines as one heating line. .. When two dot lines are used as one heat generating line, the resolution in the paper feeding direction of the thermal paper is lower than that in the 1ply printing mode, that is, a gap is generated between the previous dot line and the next dot line. Since the printing energy ε becomes large, the dots actually printed become large as compared with the 1ply printing mode, which is sufficiently practical. Therefore, in this embodiment, the printing speed is prioritized. In this case, if high quality printing quality is required, it can be dealt with by reducing the speed.

As described above, 1 is set in the 2ply print mode.
Since a higher printing energy ε is required as compared with the ply printing mode, the energization pattern is as shown in FIG. In FIG, a of ^c G _a ^b group, b is conduction timing, c is shows the timing when the double the energization timing indicates the energization timing before the portion surrounded by a thick line frame dot line ..

Therefore, the energization control as shown in FIG. The print pulse width t in the equation (2) is doubled, but the printing energy ε is doubled while suppressing the decrease in printing speed.

That is, in the present specific example, for example, when two sheets of heat-sensitive paper are printed in an overlapping manner as compared with the case of one sheet, printing energy is required accordingly, and therefore each heating element is printed. Because it is necessary to increase the energy given to 2,
The problem is solved by increasing the number of times of energization. Then, specifically, as shown in FIG. 20, the additional energization is performed at the normal energizing pulse generation time point T-11, and the energizing pulse generation time point is T-1.
2

Similarly, additional energization is performed at each energizing pulse generation time T-n1 at the energizing pulse generation time T-n2. The energizing time in the additional energizing is not particularly limited, but the type of thermal paper, the number of sheets,
It is appropriately determined depending on the printing speed and the like. For example, in the case of two thermal papers, if the normal energizing time is 1, the ratio of the additional energizing time can be 0.5.

As described above, in the specific example shown in FIG. 20, the print data for the heating element 2 that is energized by the normal energizing pulse and the print data for the heating element 2 that is energized by the additional energizing pulse are It is preferable that they are the same.
On the other hand, if the printing energy for the printing block is simply increased, the area of color development on the printing sheet is enlarged, and the probability of overlapping with other printing data is increased, which is also a cause of lowering the resolution.

Therefore, in this example, the printing rate determining means 6 is used together when the normal energization process is performed or when the additional energization is performed. When the printing rate exceeds a predetermined value, for example, 50%, the energizing time for each block in one line can be further divided. In this case, 1 line is 16
This is possible when used in bit configuration.

That is, the energized dots of one print line are energized separately for each dot in the double density mode. In other words, the print coloring energy is proportional to the square of the applied voltage as described above. Further, since a power source such as a battery has an internal resistance, a voltage drop occurs when an excessive current is applied.

Therefore, depending on the load, even if the same energization time is applied, the coloring energy for each dot fluctuates, and a situation occurs in which the printing quality is affected. The line thermal printer according to the present invention employs a method of dividing a print block in order to avoid such a problem, and a specific method thereof is, as shown above, in a block to be energized. The number of energized dots is calculated, and the print block is divided according to the calculated number of dots, and divided into 1/2 or 1 /
Determine 4 divisions.

When the divisional energization in the target print block is completed, the target print block is moved to the next print block and the same operation is performed. In this case, the threshold value of the number of dots that determines divided energization depends on the current capacity of the power supply (battery) used. When the print rate is low, the data in one print block can be printed at one time without being divided.

When the print ratio is slightly high, the dots in one print block are divided by software in the print block,
It is also possible to use a method in which printing is performed with a time lag in order. When the printing rate is very high, the total dots of one print block are divided into 1/4 by software from one end and the dots are sequentially printed. In this way, in this specific example, the current load on the battery can be controlled by changing the print data division ratio according to the print ratio for printing, and stable print quality can be obtained. Becomes

As described above, the two operation modes enable optimum printing according to each application, and the printing rate determination means 5 reduces the influence of the voltage drop due to the internal impedance of the battery to stabilize the printing quality. Be done. As described above, in this embodiment, the energization control unit can control the energization of the print head in a state where the printing cycle is fixed, and the number of energizations to the print head is determined based on a plurality of print modes according to the type of thermal paper. The printing energy per unit area can be changed.

Therefore, it is possible to prevent a decrease in the printing speed even when driven at a low voltage of, for example, about 4.8 V, and it is possible to obtain good printing quality on various types of thermal paper. Further, since the thermal paper generally has a higher print density according to the print energy, it is possible to print with a gray scale by controlling the number of times of energization as in the present embodiment.

In the above embodiment, a print head having a heating element and divided into five printing blocks of 64 dots and having a total of 320 dots has been described as an example.
Not limited to this, it goes without saying that the total number of heating elements included in the print head, the number of divisions into print blocks, and the like are arbitrary according to the given device and purpose. Further, the number of times of energization is not limited to this embodiment, and can be freely determined.

The line thermal printer according to the present invention is
The print data including a predetermined character code or the like input from an appropriate input means is received by the computer 13 which is the central processing means, and the font data corresponding to the character stored in the computer 13 is used as a print sheet. Although printing is performed, high resolution printing has become possible in recent years as the manufacturing technology of the thermal line head has improved.

Therefore, it is becoming easier to change the character size of reduced characters, double-width characters, and the like. In the present invention, as described above, the standard character size is programmed so that one dot is printed twice as vertically and twice as horizontally. In such a situation, in the high quality print mode (HQ), printing is performed without performing reduction processing after the enlargement conversion described above. In this case, the print rate is enlarged. It will be higher than the one before conversion.

On the other hand, in the high speed printing mode (HS), reduction processing (thinning of printing dots) is performed in the vertical direction or the horizontal direction after the enlargement conversion to reduce the actual printing rate. .. Since the printing rate does not increase in the high speed printing mode (HS), the printing rate in each divided block of the printing block is lower than the threshold value for the printing rate determination as compared with the high quality printing mode (HQ). As a result of the large number of states, the printing speed is considerably increased.

However, with respect to the print density, the number of print dots decreases, and therefore the tendency that the print density becomes thin is inevitable. Finally, a method of controlling the printing operation of the line thermal printer according to the present invention will be described with reference to the block diagrams of FIGS. In step (1), first, the data for one line of the predetermined print data to be printed is input from the appropriate input means 14 to the receiving means of the computer 13 which is the central processing means, and the print data is received in the receiving buffer. It is taken in by 15 (step (2)).

Then, in step (3), the data analysis means 16 analyzes each of the plurality of input data of the input print data, and the control code of the print data is the flag register 17 or the like. Information such as the print mode is determined through the modified data processing means (step (4)), and the modified data corresponding to each of the input data of the code buffer 19 is passed through the data block 18. Buffer (20-1 ~ 2
0-N) (step (6)).

On the other hand, in step (3), the print data possessed by the print data is separated, and the print data management means executes appropriate processing (step (5)). The data is stored in the code data buffers (21-1 to 21-N) corresponding to the respective input data of the code buffer 19 via 18 (step (6)).

1 to be printed by the step (6)
A code buffer of print data for lines is completed.
Next, with respect to each data in the code buffer 19, first, the modification data is read out and a determination process as to what print mode code is carried out is performed (step (7)).

Based on the result, the task table 22
From a given task unit (eg task unit #
1) 22-1 is selected. After that, the modified data and the code data of the predetermined data stored in the code buffer 19 are transferred to the selected task unit # 1 (step (8), and the task unit # 1 has a built-in function. The print data reading means 81 and the CG font data searching means 82 are used to read predetermined print data from the CG font table 24 according to the code address of the code data, determine the print mode, and finally convert the print data. Using the print mode program based on the modified data search using the means 83, the searched print data is converted into a predetermined format.

In step (9), the print data converted by the task unit # 1 is transferred to the image buffer 25.
The print data that has been transferred to the print data and converted for each print data is stored in a predetermined buffer position. In step (10), the number of energized heating elements 2 is calculated based on the print data in the image buffer 25, and the print rate is calculated for each print block.

If the print ratio is larger than the predetermined threshold value, the process proceeds to step (11) to further divide the print data in the print block. If the printing ratio is smaller than the predetermined threshold value in step (10), the process proceeds to step (12) without passing through step (11). In step (12), the number of energization times is determined according to the print mode determined by the type and number of thermal papers.

In step (13), in step (12)
The print data processed in (1) is transferred to the print head 1 via the print head data transfer means included in the print block control means 12. The print head 1 includes latch circuits 201 to 20n connected to a plurality of heating elements 2 and flip-flops 101 to 10n connected to the latch circuit.
n, and the heating element 2 is driven by the heating means included in the printing block control means 12 via the driving circuits 301 to 30n, respectively.

In step (13), the latch control signal of the print data is supplied to the latch circuit, and the serial data transfer signal is supplied to the flip-prop circuit. In step (14), the print speed, print voltage, print temperature, print rate, print mode, type of thermal paper, number of sheets, etc. are judged from the above print data, and based on the result, energization is carried out in step (15). The driving condition of the time control means is calculated, and in step (16),
Based on the output of step (15), the heating means included in the print block control means 12 is driven to individually drive each of the predetermined heating elements 2.

Further, in step (17), based on the print data, predetermined data is output from the print sheet transfer means 11 and the print sheet transfer motor is driven to drive the print sheet. The platen roller 8 that is a transfer unit is rotated by a predetermined angle to move the print sheet by a predetermined minute distance.

[0102]

According to the present invention, the heating elements in the plurality of printing blocks simultaneously heat and print on the thermal paper. That is, for example, printing can be speeded up even by driving at a low voltage of about 5V. When the number of heating elements in the print block to be heated by the heating means exceeds a predetermined number, the print block is further divided and heated by the heating means, so that the voltage drop due to the internal impedance and the common conductor in the head Printing defects such as head loss can be prevented.

Therefore, it is possible to prevent a print failure due to a voltage drop due to the internal impedance and a loss in the head due to the common conductor in the head, and it is possible to perform printing at high speed even when driving at a low voltage of about 5V. Further, in the present invention,
The energization control unit can control the energization of the print head with the print cycle fixed, and the number of energizations to the print head is determined based on a plurality of printing modes according to the type of thermal paper to determine the printing energy per unit area. Can be changed.

Therefore, it is possible to prevent a decrease in printing speed even when driving at a low voltage of, for example, about 4.8 V, and it is possible to obtain good printing quality on various thermal papers.

[Brief description of drawings]

FIG. 1 is a schematic view of a print head of a line thermal printer according to the present invention.

FIGS. 2A and 2B are views showing the relationship between print data and actual printing in a high-speed printing mode.

FIG. 3 is a diagram showing energization timing in a high-speed printing mode.

FIG. 4 is a diagram showing a relationship between print data and actual printing in a high quality printing mode.

FIG. 5 is a diagram showing energization timing in a high-quality print mode.

FIG. 6 is a diagram showing a relationship between print data and actual printing in the reduced print mode.

FIG. 7 is a diagram showing a relationship between print data and actual printing in a double-density printing mode.

FIG. 8 is an equivalent circuit diagram of a print head.

FIG. 9 is a diagram showing a relationship between a print cycle and print density.

FIG. 10 is a table showing the relationship between the printing rate and the printing speed.

FIG. 11 is a diagram illustrating an outline of a drive control system of a line thermal printer according to the present invention.

FIG. 12 is a diagram showing an example of data processing used for drive control of a line thermal printer according to the present invention.

FIG. 13 is a diagram showing an example of similar data processing.

FIG. 14 is a diagram illustrating a principle of improving print quality according to the present invention.

FIG. 15 is a diagram illustrating a printing method of a conventional line thermal printer.

FIG. 16 is a diagram illustrating a printing method of a line thermal printer according to the method of the present invention.

FIG. 17 is a diagram for explaining a comparison between the multiple burn method of the present invention and the conventional method.

FIG. 18 is a diagram showing a normal energization timing in the second aspect of the present invention.

FIG. 19 is a diagram showing energization timing in the 1ply print mode according to the present invention.

FIG. 20 is a diagram showing energization timing in the 2ply print mode according to the present invention.

FIG. 21 is a diagram showing a part of the entire control system of the line thermal printer according to the present invention.

FIG. 22 is a diagram showing a part of the entire control system of the line thermal printer according to the present invention.

FIG. 23 is a schematic view of a conventional print head.

FIG. 24 is a diagram showing energization timing in a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Print head 2, 21-2n ... Heating element 3a-3e ... Printing block 4 ... Heating means 5 ... Printing rate determination means 6 ... Energization control means 7 ... Sheet 8 ... Platen roller, sheet transfer means 10 ... Print data memory means (ROM) 11 ... Sheet transfer means control means 12 ... Print block control means 13 ... Central processing means (CPU) 14 ... Print data instruction (input) means 15 ... Receive buffer 22 ... Task table 25 ... Image buffer 26 ... First image buffer 27 ... second image buffer 101 to 10n ... flip-flop 201 to 20n ... latch circuit epsilon ... energy V ... applied voltage per unit area V _S ... saturation voltage R ... heating element resistance t ... pulse width S ... heating element area R ₀ to R ₆₃ ... heating element resistor r ₀ ~r ₆₃ ... lead resistance R _c ... common conductor resistance i ₀ through i ₆₃ ... originating Thermal lead current V _{R0 to} V _R63 ... Heating element voltage V _{r0 to} V _r63 ... Lead voltage V _c ... Common voltage Σi ... Common current

Claims (1)

Claim: What is claimed is: 1. A line thermal printer which electrically heats a print head having a plurality of heating elements to develop a color on a thermal paper in contact with the heating elements for printing. The printer includes a print head including a plurality of print block groups obtained by dividing the plurality of heat generating elements into a predetermined number, and heating for electrically heating the heat generating elements based on predetermined data for each print block. And a heating means configured to simultaneously heat at least two printing blocks selected from the printing block group. 2. The thermal printer is provided with a plurality of different print modes, and the number of the selected at least two print blocks simultaneously heated by the heating means according to the print modes, and the number of print blocks in the print blocks. 2. The thermal printer according to claim 1, wherein the pattern of the heating element to be heated is changed based on the data of 1. 3. A print ratio determining means for determining the number of heating elements to be heated with respect to the total number of heating elements in one printing block among the at least two printing blocks selected based on the data. The heating means further divides the printing block and heats the printing block when the number of heating elements to be heated by the heating means exceeds a predetermined number by the printing rate determining means. Or the thermal printer according to 2. 4. A line thermal printer that electrically heats a print head having a plurality of heating elements to develop color on a thermal paper in contact with the heating elements and prints the line. Is provided with a heating means for electrically heating the heating element based on predetermined data, and further, a plurality of print modes according to the type of the thermal paper and a print head with a fixed print cycle are provided. An energization control unit for controlling energization is provided, and the energization control unit determines the number of energizations to the print head based on the print mode, and changes the printing energy per unit area. A line thermal printer characterized by being configured. 5. The line thermal printer further has a plurality of print modes according to the type of the thermal paper, and an energization control means for controlling energization to the print head in a fixed printing cycle. 4. The energization control means is configured to determine the number of energizations to the print head based on the print mode and vary the printing energy per unit area. Line thermal printer described. 6. A printing rate determining means for determining the number of heating elements to be heated with respect to the number of pre-heating elements in the printing block based on the data is provided, and the printing rate determining means heats the heating means. 5. The line thermal printer according to claim 4, wherein when the number of heating elements to be heated exceeds a predetermined number, the heating means is configured to further divide the printing block to heat it.