JP3074575B2 - Thermal printer - Google Patents

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 suitable for use in a field such as a handy terminal and which is provided 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 in which printing is performed by electrically heating a print head corresponding to characters and figures on heat-sensitive paper that 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, small portable equipment, for example, a handy terminal or the like, is driven by a low voltage such as a battery drive of about 4.5 to 6.5 V or a single power supply of 5 V. Cannot be printed. Therefore, for example, a line thermal printer that operates at a low voltage of about 5 V is required.

On the other hand, the thermal paper used in this thermal printer is not limited to 1 ply paper which is usually used, but is, for example, a color which develops when heat of different temperatures is sensed, that is, when different printing energy is applied. There are various types of paper, such as red-black paper and 2-ply paper which does not develop color unless a printing energy larger than the normal printing energy for thermally sensing 1 ply thermal paper is applied.

Therefore, in order to obtain good printing quality on various types of thermal paper, a line thermal printer that can change the printing energy per unit area according to the type of 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 the line thermal printer has a heating element 2 of 320 dots per dot line and 8 print elements.
It is composed of four print blocks 3a to 3d divided for each 0 dot. In the above configuration, when printing on a predetermined thermal paper, first, based on the predetermined data, the heating element 2 in the print block 3a is energized at a high voltage of, for example, about 12 V for a predetermined time. As shown in (1), printing is performed at the thermal paper position corresponding to the printing block 3a (shaded area), and then the paper is slightly fed.

Hereinafter, similarly, the printing blocks 3b, 3c, 3
d are sequentially energized, and the print blocks 3b,
Printing is performed at the thermal paper position corresponding to 3c and 3d (shaded area), and printing of one dot line is completed.

[0008]

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

Further, there is a problem that high-speed printing cannot be performed by driving at a low voltage. That is, in order to obtain the required 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 Here, ε: energy per unit area V: applied voltage V _S : saturation voltage R: heating element resistance value t: pulse width S: heating element area In order to increase printing energy ε,
Whether the saturation voltage V _S is reduced, the heating element resistance value R is reduced, the heating element area S is reduced,
The pulse width t must be increased.

However, there is a limit to reducing the heating element resistance value R due to the print head material, and when the heating element resistance value R decreases, the current i flowing through the heating element 2 increases. Therefore, the saturation voltage V _S increases. The saturation voltage V _S becomes ineffective energy and has no effect on print coloring. To explain this, current i = (V−V _S ) / R, which is a current flowing through a single heating element, and the total current flowing through the actual print head 1 is

[0011]

(Equation 1)

## EQU1 ## That is, the saturation voltage V _S is equal to the current i
, And approximately V _S = ai + b. (Actually, the switching transistor becomes non-linear due to the saturation characteristics of the switching transistor.) Therefore, when the current i increases, the saturation voltage V _S increases and V−V _S decreases, so that the printing energy ε decreases.

When a battery is used, the applied voltage V itself is equal to the current i due to the presence of internal impedance.
New problems, such as a voltage drop due to fluctuations depending on the voltage and a loss in the head due to a common conductor in the head, which may cause a printing failure. Therefore, the optimum range of the heating element resistance R is naturally determined, and accordingly, the pulse width t must be necessarily increased.

Increasing the pulse width t generally increases the printing cycle, so that the printing speed is reduced, and the pulse width T cannot be made too large to realize high-speed printing. Decreasing the pulse width generally shortens the printing cycle, so that the printing speed is increased. However, there is a problem that the printing energy ε decreases.

Therefore, the present invention prints at 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 an internal impedance and a loss in the head due to a common conductor in the head. One object is to provide a thermal printer and, for example, 4.8V
It is another object of the present invention to provide a line thermal printer capable of obtaining a good printing quality on various types of thermal paper while preventing a reduction in printing speed even at a low voltage drive of about 5.0 V.

[0016]

The line thermal printer according to the present invention employs the following basic technical configuration to achieve the above object. That is, a first aspect of the line thermal printer of the present invention is a line thermal printer which electrically heats a print head having a plurality of heating elements and develops color by printing on thermal paper in contact with the heating elements to perform printing. The line thermal printer includes a print head including a plurality of print block groups obtained by dividing the plurality of heating elements into a predetermined number, and electrically connecting the heating elements based on predetermined data for each of the printing blocks. Heating means for heating at least two printing blocks selected from the printing block group, wherein the heating means is configured to simultaneously heat at least two printing blocks selected from the printing block group. The second mode is a line thermal printer that electrically heats a print head having a plurality of heating elements and develops color by printing on thermal paper in contact with the heating elements. The line thermal printer includes a heating means for electrically heating the heating element based on predetermined data in the print head, and further includes a plurality of printing modes corresponding to the type of the thermal paper, and a printing cycle. Power supply control means for controlling the power supply to the print head while the power supply is fixed, wherein the power supply control means determines the number of times of power supply to the print head based on the print mode, and This is a line thermal printer configured to vary the printing energy per area.

[0017] The thermal printer has a plurality of different printing modes, and the heating means heats based on the number of the printing blocks to be heated simultaneously and the data in the printing blocks in accordance with the printing modes. And a printing rate determining unit that determines the number of heating elements to be heated with respect to the number of all heating elements in the print block based on the data. If 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 that the heating means is configured to further divide and heat the print block. .

[0018]

According to the present invention, the heating elements in the plurality of printing blocks are simultaneously heated by the heating means, thereby printing on the thermal paper. That is, for example, printing can be speeded up even when driven at a low voltage of about 4.8 V to 5 V. 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, thereby causing a voltage drop due to internal impedance, a common voltage in the head. Printing troubles such as loss in the head due to conductors are prevented.

Therefore, a printing failure caused by a voltage drop due to the internal impedance and a loss in the head due to a common conductor in the head is prevented, and printing is performed at high speed by driving at a low voltage of about 4.8 V to 5 V. In the present invention,
The power supply to the print head is controlled with the print cycle fixed by the power supply control means, and the number of times the power is supplied to the print head is determined based on a plurality of print modes according to the type of thermal paper, and printing per unit area is performed. The energy is varied.

Therefore, for example, 4.8 V to 5.0 V
Even at a low voltage drive, a reduction in printing speed is prevented, and good printing quality can be obtained for various types of thermal paper.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 11 are views showing one embodiment of a thermal printer according to the first embodiment of the present invention. First, the configuration will be described.

As shown in FIG. 1, the print head 1 of the thermal printer according to the present embodiment is composed of five print blocks 3a to 3e obtained by dividing a heating element 2 of 320 dots per dot line into 64 dots. I have. In addition, 4 is a heating means and 5 is a printing rate determination means. 6 is the second
This is the energization control means used in the embodiment.

The heating means 4 energizes the heating elements 2 for each of the printing blocks 3a to 3e based on predetermined data, and prints the heating means 4 simultaneously heating according to a plurality of different printing modes to be described later. The number of blocks 3a to 3e,
The pattern of the heating element 2 to be heated in the printing blocks 3a to 3e is changed. Each of the heating elements used in the present invention has 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 configured to be individually and independently heat-controlled.

The printing ratio measuring means 5 includes printing blocks 3a to 3a.
3e, the number of heating elements 2 to be heated relative to the number of all heating elements 2, that is, when the so-called printing rate becomes 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 reduced to increase the printing cycle.

As described above, the energy required for printing is Therefore, in order to reduce the applied voltage V, the heating element resistance value R must be reduced or the pulse width t must be increased. Therefore, in the present embodiment, in order to perform printing at a low voltage and at a high speed in consideration of these, the applied voltage V is set to 4.5 to 4.5.
6.5V, heating element resistance R is 45Ω ± 10%, heating element area S is 6 heads / mm, 1PLY, W0.165mm × H0.165mm for label paper, W0.165mm × 2PLY H is set to be 0.330 mm.

In order to increase the pulse width t without sacrificing the printing speed, in the present embodiment, the heating means 4 heats the heating elements 2 in the plurality of printing blocks 3a to 3e at the same time. 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 a platen roller or the like driven by the motor M to move the paper 7 as a print target sheet at a predetermined speed and a predetermined pitch in a predetermined direction. 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, a sheet transfer means control means 11 for controlling the sheet transfer means 8, and a print for driving and controlling the print blocks of the printing section. Block control means 12 is provided. The sheet transfer means control means 11 and the print block control means 12 store print data input instructing 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 constituted by, for example, a ROM or the like.

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

On the other hand, the control code CD is information for specifying a mode type such as a high-speed print mode, a high-quality print mode, a double-density print mode, and the like.
To execute the flag and parameter setting process and transfer it to the decoration data buffer 18-1 of the data block 18. Thereafter, the information in the data buffer 18 is transferred to a code buffer 19 composed of a RAM or the like.

The code buffer 19 stores buffers (20-1, 20-2) and (21-1, 21-2) for modification data and code data for each data.
.. (2n-1, 2n-2), and the transferred data are stored in respective buffers. 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 is provided with task units 22-1, 22-2,..., 22-n which individually store a plurality of tasks (task # 1 to task #N). Such task units 22-1, 22-
2,... 22-n include functions corresponding to each of the modification data corresponding to the high-speed printing mode, the high-quality printing mode, the double-density printing mode, and the like. Any of the tasks is selected by judging the flag of the qualification data of each data transferred from.

If the flag of the modification data included in the data 1 transferred from the code buffer 19 indicates the high-speed print mode, it corresponds to a program for processing the high-speed print mode. For example, the task unit 22-2 including the task # 2 to be executed is selected, and the code data of the data 1 is simultaneously transmitted to the task unit 22-2.
-2.

Thereafter, the code data of the data 1 is read 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 font data read by the task unit 22-2 is processed in the high-speed print mode in accordance with the program of the modification flag of the task unit 22-2, and the result is stored in an image buffer. 25 and stored.

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 stores the image to be printed 1
The print data for one line before the line is stored.

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

In the present invention, print data for one line constituting one dot is stored in one image buffer. Further, in the present invention,
At the predetermined timing based on the print data stored in the image buffer, each heating element 2 of each printing block is energized to perform printing.
The line is divided into a plurality of times and energized. For example, one line is divided into five times and the energizing process is executed.

Accordingly, since 32 dots are employed in the double density mode, it is necessary to carry out energization processing 160 times with 32 lines × 5 energizations in order to print one character, and in the normal mode. Uses 16 dots, so 16
80 times of energization processing are required for 5 times of line energization. or,
When the present invention employs the double density mode and the normal mode, the configuration of the heating element 2 according to the present invention is such that four heating element units U1 to U1 as shown in FIG. 1 or FIG.
4 is preferable.

A specific example of the printing procedure according to the present invention will be described below. The line thermal printer of the present embodiment has four types of modes: a) a high-speed printing mode, b) a high-quality printing mode, c) a reduced printing mode, and d) a double-density printing mode. The mode is a so-called three-burn system in which the heating elements 2 in three consecutive printing blocks 3a to 3e are simultaneously heated by the heating means 4, and the mode is three-burn.
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 re- Becomes

Therefore, when the printing ratio becomes higher than the predetermined value by the printing ratio determining means 5, the number of batch print data is reduced, and the printing cycle is increased. The printing rate determination means 5 performs the printing in units of the printing blocks 3a to 3e so that the printing is performed without lowering the overall execution printing speed. In the high-speed printing mode, the number of printing dots in the horizontal direction is reduced by 50% in order to increase the printing speed. The relationship between the printing data and the actual printing is shown in FIG. As shown in FIG. 2, two pixels in the vertical direction in a 2 × 2 matrix are printed for one pixel data. In the image printing mode, as shown in FIG. Thus, two pixels in a diagonal direction in a 2 × 2 matrix are printed.

According to the present invention, the timing of energization is the fifth.
As shown in the figure, T (α, β)
Represents the α-th pulse, β represents the print block of the β-th group, and * represents the energization of the immediately preceding dot line. That is, in the present invention, an example is shown in which one line l is energized five times when printing processing of one dot line l is performed, and T-1 to T-5 in FIG. 1
The line 1 is divided into five times, and the number of the block to be energized at the time of the first pulse generation T-1 is designated, and the number of the block to be energized at the time of the second pulse generation T-2 is designated. The same applies to T-3 to T-5 below. As described above, in the present invention,
One specific example is to use two image buffers in combination. FIG. 5 is a block diagram showing a first image buffer 26 storing print data to be printed on line l.
And a second image buffer 27 that stores the print data that has been printed or is being printed on the line l-1 one line before that.

In the printing operation of the present invention, when one energizing operation in one line 1 is completed, the sheet 7 to be printed is driven by the motor M based on a control signal from the sheet transfer control means 11. The seat 7 is configured to be moved by a very small distance by being rotated by a very small 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
By causing the blocks 3d and 3e to be energized, the heating elements 2 included in each block are individually heated based on the print data stored in each block.

Next, 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
Is energized with the block 3e in the image buffer 27, thereby individually heating the heating elements 2 included in each block based on the print data stored in each block.

Similarly, when the third energizing pulse T-3 is generated, the blocks 3a,
By energizing 3b and 3c, each heating element 2 included in each block is individually heated based on print data stored in each block. That is, in the high-speed printing mode in this embodiment, in the energization processing of one printing line, three printing blocks out of a plurality of printing blocks (five in this embodiment) are simultaneously energized. A three-burn system for processing is adopted, thereby realizing high-speed printing.

(B) The high-quality printing mode employs a so-called two-burn system in which the heating elements 2 in two continuous printing blocks 3a to 3e are simultaneously heated by the heating means 4, and the printing is performed in two burns. Printing blocks adjacent between the blocks 3a to 3e are energized simultaneously. In addition, since high quality printing is performed, the printing rate is doubled as compared with the high speed printing mode. That is, the number of dots to be simultaneously energized is This is about 30% higher than the high-speed print mode, and the overall print speed is lower than in the high-speed print mode.

The high quality mode corresponding to the printing of such 2PLY paper, since the mode number of print dots is not Ridakuto, the relationship between the actual printing and the print data, character printing mode, the image print mode both, Figure 4 As shown in (1), all pixels in a 2 × 2 matrix are printed for one pixel data. The energization timing is indicated by T (α, β) as shown in FIG. 5, and α of T (α, β) is α-th.
The third pulse, β, indicates a print block of the βth group, and * indicates energization of the immediately preceding dot line.

The description of FIG. 5 is the same as that of FIG. 3 except that the print block for energizing when one energizing pulse is generated is 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 that has 320 dots in one dot line and is divided into 5 blocks of 64 dots, the conventional method uses one block unit. The driving method is adopted in order. In this method, it is necessary to supply the coloring energy to the paper from the heating element by one energization. However, as shown in FIG. 17B, in contrast to the above method, in the method of the present invention, the width of the reference energization time is reduced to half, and the plurality of adjacent blocks are energized at once. In this method, printing is completed in half the time of the conventional method.

Further, since the heat generated by the energizing heating element decreases exponentially, the coloring energy tends to increase as the printing cycle becomes longer. When the speed is increased by this method, a printing cycle is shortened, so that a synergistic effect that efficient driving can be performed by utilizing the heat storage effect also appears. 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 a conventional printing method, in which one dot line is composed of 320 dots and 64 dots are included in one block.
Although the configuration is the same as that of the present invention in that it is composed of a plurality of blocks, in the conventional method shown in FIG. 15A, only one block is energized in one energizing pulse. Even if the next energizing pulse arrives in the block and the energizing process is performed, there is a problem that some gaps and gaps are generated between the print data and the print data processed when the previous energizing pulse (sixth previous pulse) is generated. There is a problem that a large amount of load is required for one energization.

The conventional example shown in FIG. 15B is an example in which three consecutive blocks are energized simultaneously by one energizing pulse, but the remaining printing blocks are energized individually by another energizing pulse. However, even in this specific example, there is a problem that a slight gap and a gap are generated between the print data processed by printing when the previous energizing pulse was generated and the data printed by the current energizing. doing.

However, in the present invention, FIG.
As shown in FIG. 16A and FIG. 16B, in both the two-burn system and the three-burn system, a plurality of print blocks surrounded by a thick line in FIG. Since the energizing process is performed simultaneously with the energizing pulse, the same print data is printed multiple times on the print sheet multiple times with slight deviations in the print data, so the print density is improved. Since the density can be reduced, it contributes to the improvement of the printing speed.

C) The reduced print mode is a mode in which the number of print digits in one line is larger than that in the high-speed print mode. The relationship between print data and actual printing is as shown in FIG. In this case, three pixels are printed with respect to the data of two pixels, and the relationship between the print data a, b and the data α, β, γ to be reduced and printed in FIG. It is exchanged based on.

[0052]

[Table 1]

The energization timing is set the same as in the high-quality print mode. d) Double density print mode is 3
In this mode, the number of print data is 20 dots / line. As shown in FIG. 7, the relationship between print data and actual printing is that one pixel is printed for one pixel data. This mode enables printing of bar codes and the like because high-density printing is possible.

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

Using the Multiple Burn System According to the Invention
FIG. 14 shows the principle of improving the print quality, that is, the density.
Shown in That is, the energization timing chart of FIG.
(TMG) 1st print block 3 burner
Energizing pulse F using the equation₁~ F _ThreeEnergized at
The processing is performed (see FIG. 14B). On the other hand,
For one print block N, one line
Since the energization process is performed only once, the hatched portion in FIG.
Only the print density distribution of the print data as shown in the
There is a blank part between adjacent print data because there is no
However, the present invention has a disadvantage that the concentration appears to decrease.
Then, the same print block N must be energized three times in a row.
Also, since the printing sheet moves slightly at each energization,
It is possible to obtain a print density distribution as shown in FIG.
And the density appears to be high.

Next, of the thermal head used in the present invention,
FIG. 8 shows an equivalent circuit. In the figure, R₀~ 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 the heating 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 referred to as the lead voltage
V)_cIs the voltage applied to the common conductor resistance
と い う i is the common conductor resistance R_cCurrent flowing through
(Hereinafter, referred to as a common current), and the heating lead current i₀
~ I ₆₃Total.

That is, the heating element voltage V _RO and the read voltage V
_ro, common voltage V _c is 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 part, the internal transistor Tr part, etc., and A _(i) · Σi
Correlates with the number of energized dots in the heating element 2, 64 dots of one print block 3a-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.

The effect on the energy ε is extremely large because the value of the heating element resistance R ₀ is small. this is,
If 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 total resistance is small and the influence is small. However, when the value of the heating element resistance R ₀ is small, the small value of the lead resistance r ₀ is large for the total resistance. This is because the effect becomes larger.

Now, consider the case where the heating element 2 for n dots is energized. (However, when locked with the same printing, up to 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.

[0061] Here, the applied voltage V is different from the case of the constant voltage, if the battery, the battery internal impedance, the original voltage of the actual voltage V = Battery V _D - from the battery internal impedance r _b · .SIGMA.i _{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 · T / S.

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

In this case, the number of dots to be processed is 96 dots (3 burns) in the high-speed print mode, and 128 dots (2 burns) in the high-quality print mode. When the ratio exceeds a certain ratio (for example, 75% in the case of the high-speed printing mode), the number of divisions of the heating elements 2 in the printing blocks 3a to 3e is increased, so that the number of energization is reduced.

At this time, the subdivision reduces the printing speed, and promotes the energy (heat) diffusion from the print head. That is, as shown in FIG. 9 , when the printing speed is reduced, the heat of the head is diffused.
Work to raise the temperature of the head heating element
As a result, more energy ε is required to obtain the same temperature. That is, if the printing speed is too fast,
When the pulse width T becomes small and sufficient energy cannot be obtained, on the other hand, when the printing speed is too slow, the density becomes low and
If the pulse width T is applied until the dots are 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.
By changing the setting values of the printing speed and printing rate based on the table values according to the paper quality etc. of the thermal paper used,
Stable printing quality and high speed can both be achieved. As described above, in the present embodiment, the heating elements in the plurality of printing blocks are simultaneously heated, and printing is performed on the thermal paper. That is, for example, printing can be performed at a high speed even at a low voltage of about 5 V.

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

The above embodiment has been described by taking as an example a print head having a total of 320 dots, which has a heating element and is divided into five printing blocks of 64 dots each.
The present invention is not limited to this, and 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 depending on the given device and purpose. Next, a second embodiment of the line thermal printer according to the present invention, that is, a configuration of a line thermal printer configured to have a plurality of print 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 the line thermal printer according to the first embodiment shown in FIG. However, in this specific example, the energization control means 6 shown in FIG. 3 is utilized. The power supply control means 6 in this specific example controls the power supply to the print head 1 by the heating means 4 in a state where the printing cycle is fixed, that is, in a state where the paper feed 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, and a plurality of printing blocks 3 It is not necessary to select a block so as to energize at the same time.

As described above, the energy required for printing is As described above, the pulse width t is set to be small from various conditions, but the printing energy ε is increased by energizing a plurality of times.

In this embodiment, the applied voltage V is 4.8 V, the heating element resistance R is 45 Ω ± 10%, the heating element area S is 6 heads / mm, 1 ply, and W0 for label paper. .165mm × H0.165mm, W0.165mm × H0.165mm or W0.165 for 2ply
mm × H0.330 mm. This is substantially the same condition as in the first embodiment.

Further, in order to avoid sacrificing the printing speed, in the present embodiment, the heating means 4 uses the plurality of printing blocks 3a to 3a.
Of course, it is also possible to heat the heating elements 2 in 3e at the same time. Next, the operation will be described. The line thermal printer of this embodiment is provided with two types of modes such as a) 1 ply print mode and b) 2 ply print mode, and the energization timing is as shown in FIG.

[0072] It should be noted that, in the figure, a of G _a ^b group, b
Indicates the energization timing, and the portion surrounded by the thick line frame indicates the 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,
Fifth energization of group 1, fourth energization of group 2, third energization of group 3, second energization of group 4
This means that the second energization is performed simultaneously.

The number of times b is determined according to the capacity of the power supply. A) In the 1 ply print mode, when a single print energy ε is required, as in the case of 1 ply thermal paper, for example, as shown in FIG.
The number of times of energization is determined and controlled. In the figure, 0
Means a non-energized state.

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

B) In the 2 ply printing mode, when a higher printing energy ε is required as compared with 1 ply thermal paper, such as 2 ply thermal paper, the speed is increased by using two dot lines as one heating line. . When two dot lines are used as one heating line, the resolution of the thermal paper in the paper feeding direction is reduced as compared with the 1 ply print mode, that is, a gap is generated between the previous dot line and the next dot line. Since the printing energy ε is large, the dots to be actually printed are large as compared with the 1 ply printing mode and are 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, in the 2 ply print mode, 1
Since a higher printing energy ε is required as compared with the ply printing mode, an energization pattern as shown in FIG. 20 is obtained. 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, by performing the energization control as shown in FIG. 20, Although the printing pulse width t in the equation (2) is doubled, the printing energy ε is doubled while a decrease in printing speed is suppressed.

That is, in the specific example of the present case, for example, when printing two sheets of thermal paper in a superimposed manner as compared with a case where only one thermal paper is used, the printing energy is required accordingly, and therefore each heating element is required. Because it is necessary to increase the energy given to 2,
This problem is solved by increasing the number of times of energization. Specifically, as shown in FIG. 20, the additional energization is performed at the normal energization pulse generation time T-11, and the energization pulse generation time is set to T-1.
It is 2.

Similarly, additional energization is performed at the energization pulse generation time T-n2 with respect to each energization pulse generation time T-n1. The energization time in such additional energization is not particularly limited, but the type, number,
It is appropriately determined according to the printing speed and the like. For example, when the number of thermal papers is two, if the normal energizing time is 1, the ratio of the additional energizing time can be set to 0.5.

As described above, in the specific example in FIG. 20, the print data to the heating element 2 that is energized by the normal energizing pulse and the print data to the heating element 2 that is energized by the additional energizing pulse are: Preferably, 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 causes a reduction in resolution.

For this reason, in this specific example, when performing the normal energizing process or when applying the additional energizing, the printing rate determining means 6 is used in combination with each heating element 2 in one printing block. 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, one line is 16
This is possible when the bit configuration is used.

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

For this reason, depending on the load, even if the same energizing time is applied, the coloring energy for each dot varies, and a situation occurs that affects the printing quality. 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 the specific method is, as described above, a method of dividing a print block in a block to be energized. Is calculated, and the print block is divided according to the calculated number of dots.
4 division is determined.

When the divided 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 the split energization differs depending on the current capacity of the power supply (battery) used. When the printing rate is low, data in one printing block can be printed at a time without being divided.

When the printing rate is rather high, the dots in one printing block are divided softly in the printing block,
A method of printing with a time lag may be used. When the printing ratio is very high, the total dots of one printing block are printed by dividing them into quarters from one end by software. Thus, in this specific example, by changing the print data division ratio according to the print ratio and printing, the current load on the battery can be controlled, and stable print quality can be obtained. Becomes

As described above, the optimum printing is performed according to each application by the two operation modes, and the printing rate determination means 5 reduces the influence of the voltage drop due to the internal impedance of the battery, thereby stabilizing the printing quality. Can be As described above, in the present embodiment, the power supply to the print head can be controlled in a state where the printing cycle is fixed by the power supply control means, and the number of times of power supply to the print head is determined based on a plurality of print modes according to the type of thermal paper. Thus, the printing energy per unit area can be changed.

Therefore, even at a low voltage drive of, for example, about 4.8 V, a reduction in printing speed can be prevented, and good printing quality can be obtained for various types of thermal paper. In general, since the thermal density of the thermal paper increases in accordance with the printing energy, by controlling the number of times of energization as in the present embodiment, it is possible to print with a gradation of light and shade.

In the above embodiment, a print head having a total of 320 dots, which has a heat generating element and is divided into five print blocks of 64 dots each, is described as an example.
The present invention is not limited to this, and 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 depending on the given device and purpose. Further, the number of times of energization is not limited to the present embodiment, and can be freely determined.

The line thermal printer according to the present invention
Print data including a predetermined character code or the like input from an appropriate input means is received by a computer 13 serving as a central processing means, and font data corresponding to the character stored in the computer 13 is printed on a print sheet. With regard to printing, high-resolution printing has become possible in recent years with the improvement of the manufacturing technology of the thermal line head.

For this reason, the size of characters such as reduced characters and double-width characters can be easily changed. In the present invention, as described above, the standard character size is programmed so that one dot is enlarged twice in length and twice in width. Under such circumstances, in the high quality print mode (HQ), after the above-described enlargement conversion is performed, printing is performed without performing reduction processing. In this case, the printing rate is increased. It will be higher than before conversion.

On the other hand, in the high-speed printing mode (HS), after the above-described enlargement conversion, reduction processing (decimation of printing dots) is performed in the vertical or horizontal direction 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 in the printing block is lower than the threshold for the printing rate determination as compared with the high-quality printing mode (HQ). As a result, the printing speed is considerably increased.

However, as for the print density, the number of print dots is reduced, so that the tendency that the overall print density becomes inevitable is inevitable. Finally, a method for 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), one line of predetermined print data to be printed is input from a suitable input means 14 to a receiving means of a computer 13 which is a central processing means. 15 (step (2)).

Next, 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 stored in the flag register 17 or the like. The information such as the print mode is determined through the modification data processing means (step (4)), and the modification data is converted into the modification data corresponding to each of the input data of the code buffer 19 through the data block 18. Buffer (20-1 to 2
0-N) (step (6)).

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

According to the step (6), one to be printed is
The code buffer for the print data for the line is completed.
Next, the modification data is read out first for each data in the code buffer 19, and a determination process is performed as to which print mode code is present (step (7)).

Based on the result, the task table 22
From a predetermined task unit (for example, task unit #
1) 22-1 is selected. After that, the modification 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 is built therein. Using the print data read means 81 and the CG font data search means 82, predetermined print data is read from the CG font table 24 in accordance with the code address of the code data, the print mode is determined, and finally the print data conversion is performed. Using the printing mode program based on the modification 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 stored in the image buffer 25.
The print data converted for each print data is stored in a predetermined buffer position. In step (10), the number of heating elements 2 to be energized is calculated based on the print data in the image buffer 25, and the print rate is calculated for each print block.

If the printing rate is larger than the predetermined threshold value, the process proceeds to step (11), and the printing data is further divided in a printing block. If the printing rate 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, number of sheets, etc. of the thermal paper.

In step (13), step (12)
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 a plurality of latches 201 to 20n connected to each of the plurality of heating elements 2 and flip props 101 to 10 connected to the latch circuit.
n, and the heating elements 2 are driven by heating means included in the print block control means 12 via drive 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 printing speed, printing voltage, printing temperature, printing rate, printing mode, type of thermal paper, number of sheets, etc. are determined from the printing data, and based on the result, power is turned on in step (15). The driving condition of the time control means is calculated, and in step (16),
On the basis of the output of the step (15), the heating means included in the printing block control means 12 is driven to individually drive each predetermined heating element 2.

Further, in step (17), predetermined data is output from the printing paper transfer means 11 based on the printing data, and the motor for transferring the printing sheet is driven to drive the printing sheet. The printing sheet is moved by a predetermined minute distance by rotating the platen roller 8 as a transfer means by a predetermined angle.

[0102]

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

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

Therefore, even at a low voltage drive of, for example, about 4.8 V, a reduction in printing speed can be prevented, and good printing quality can be obtained for various types of thermal paper.

[Brief description of the 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 diagrams showing a relationship between print data and an actual print in a high-speed print 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 in a high-quality print mode and actual printing.

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 in a reduced print mode and actual printing.

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

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

FIG. 9 is a diagram illustrating a relationship between a printing cycle and a printing density.

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

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

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

FIG. 13 is a diagram illustrating an example of the same data processing.

FIG. 14 is a diagram illustrating the 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 the line thermal printer according to the method of the present invention.

FIG. 17 is a diagram for explaining a comparison between a multiple burn system and a conventional system according to the present invention.

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

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

FIG. 20 is a diagram showing energization timing in a 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 judgment means 6 ... Electricity 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 ... Reception buffer 22 ... Task table 25 ... Image buffer 26 ... First image Buffer 27 Second image buffer 101-10n Philip flop 201-20n Latch circuit ε Energy per unit area V Applied voltage 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 Heat lead current V _{R0 to} V _R63 ... heating element voltage V _{r0 to} V _r63 ... lead voltage V _c ... common voltage Σi ... common current

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-240276 (JP, A) JP-A-66-18063 (JP, A) JP-A-2-38067 (JP, A) JP-A 61-240 89771 (JP, A) JP-A-63-207273 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/35-2/375

Claims (2)

(57) [Claims] 1. A electrically heated print head having a plurality of heating elements, a line thermal printer for printing by coloring the thermal paper in contact with the heat generating member, the line thermal printer, of the plurality A print head comprising a plurality of print block groups obtained by dividing a heating element into a predetermined number, and electrically heating the heating element based on predetermined data for each of the printing blocks ;
At least two selected from the print block group
With respect to the print blocks, and a heating means for heating at the same time, the further the line thermal printer, a plurality of different indicia
A heating mode according to the printing mode.
Heat at the same time the selected at least two printing
Based on the number of locks and the data in the print block
A line thermal printer characterized by changing a pattern of a heating element to be heated by heating . 2. A print head having a plurality of heating elements is electrically driven.
Heating, heat-sensitive paper in contact with the heating element is colored to print
A line thermal printer that includes the plurality of heating elements.
Printing consisting of multiple printing block groups divided for each constant
A head and, based on predetermined data for each printing block,
To electrically heat the heating element, and upon heating,
At least two selected from the print block group
Heating means for heating the printing block simultaneously
In addition, the line thermal printer has a plurality of different marks.
A heating mode according to the printing mode.
Heat at the same time the selected at least two printing
Based on the number of locks and the data in the print block
Change the pattern of the heating element to be heated Te, further, the line thermal printer, the data
At least two printing blocks selected based on the
Of the total number of heating elements in one print block
A printing rate determining means for determining the number of heating elements to be heated is provided.
The printing means should be heated by the heating means.
If the number of heating elements exceeds a predetermined number, the heating means is turned on by the mark.
A line thermal printer characterized in that the character block is further divided and heated .