JP2000318198A - Thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermal printer good in printing efficiency and capable of shortening a printing time. SOLUTION: The feed speed of a two-color developing thermal printing medium is made variable corresponding to the developed color of the two-color developing thermal printing medium. For example, when a first color developed when first printing energy smaller in energy quantity as compared with second printing energy developing a second color is applied (S7; N), the two-color developing thermal printing medium can be fed at a speed higher than the feed speed at a time of the printing of the second color (S9) and, therefore, printing efficiency is improved and a printing time can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer, and more particularly to a thermal printer using a two-color heat-sensitive printing medium (two-color heat-sensitive thermal paper) having a characteristic of developing different colors according to applied printing energy. The present invention relates to a thermal printer for printing.

[0002]

2. Description of the Related Art Generally, a merchandise sales registration data processing device such as a POS (Point of Sales) terminal includes a receipt printer or the like for printing sales information for each transaction and issuing it as a receipt. I have. As such a receipt printer, there is a printer using a thermal printer provided with a line type thermal head excellent in silence.
Specifically, this thermal printer performs dot printing while sequentially feeding a roll-shaped receipt paper made of thermal paper in a direction orthogonal to an arrangement direction of a number of resistance heating elements constituting a line type thermal head. It is a structure to perform. In this type of thermal head, the heat generation state of the resistance heating element changes depending on the temperature of the head itself and the temperature conditions such as the heat storage (heat history) of the heat insulating layer due to the heat generated by the previous printing operation. , The print quality is degraded. Therefore, normally, an appropriate energizing pulse width (energizing time) for each temperature is preset for the thermal head, and a thermistor for constantly detecting the temperature of the thermal head is provided. The width of the energizing pulse for the resistance heating element of the thermal head is controlled based on the temperature information of the thermal head, the resistance value of the resistance heating element, and the like.

In recent years, as a thermal printing medium (thermal paper) used for a thermal printer using a thermal head, a two-color developing thermal paper that develops in two colors (for example, black and blue) has been developed and is ready for use. Have been. Such a two-color heat-sensitive paper includes an additive-type two-color heat-sensitive paper composed of two layers, a black color layer and a blue color layer, and a blue color layer, a decolorable layer, and a black color layer. There is a decoloring type two-color developing thermal paper composed of three layers. When comparing the additive-type two-color thermal paper with the decolorable two-color thermal paper, the additive two-color thermal paper has a higher storage because it does not require a decoloring layer. It is excellent in that it has properties.

[0004] Additive-type two-color heat-sensitive paper (hereinafter referred to as two-color heat-sensitive paper) has a structure in which a black color layer is laminated on a base paper and, for example, a blue color layer is further laminated thereon. Have been. The case where the two-colored thermal paper is colored and printed will be described below. Here, FIG. 11 is a graph showing the coloring characteristics of the two-colored thermal paper, in which the vertical axis indicates the recording density and the horizontal axis indicates the printing energy (mj / dot) applied by the thermal head. The dashed line A in the figure shows the color development characteristics of "blue", and the solid line B in the figure shows the color development characteristics of "black". As shown in FIG.
"Blue" develops color when a lower printing energy is applied compared to "black", and "black" overlaps "blue" when a higher printing energy is applied than that of "blue". Will develop color. In a thermal printer that prints using the two-colored thermal paper having such color-forming characteristics, for example, when printing in "blue", the printing energy E1 (about 0.20 (mj
/ dot)) to apply color, and when printing in "black", apply the printing energy E2 (approximately 0.40 (mj / dot)) to control the energization pulse width so that the color is developed. ing. That is, in the case of "black" printing, a larger printing energy is required than in "blue", so that the energizing pulse width is controlled to be longer.

[0005]

However, in this type of conventional thermal printer, for example, the printing speed during printing on one sheet of paper is constant and the printing speed is the highest when the applied energy is the highest. (When the energizing pulse width is the longest to print “black”). Therefore, even when printing "blue" having a shorter energizing pulse width than "black", the printing speed becomes the same, and there is a problem that the printing efficiency deteriorates.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal printer which has good printing efficiency and can shorten the printing time.

[0007]

According to the first aspect of the present invention,
A two-color heat-sensitive printing medium having two-color developing characteristics by applying a first printing energy for forming a first color and a second printing energy larger than the first printing energy for forming a second color. And the thermal head relative to each other, selectively driving each resistance heating element of the thermal head with respect to the two-color developing thermal printing medium and applying the first or second printing energy to perform dot printing. The transport speed of the two-color heat-sensitive thermal print medium is changed according to the color of the two-color heat-sensitive thermal print medium.

Therefore, by changing the transport speed of the two-color heat-sensitive printing medium in accordance with the color of the two-color heat-sensitive printing medium, for example, the second printing energy at which the second color is formed can be changed. When printing the first color, which is colored when the first printing energy with a smaller energy amount is applied, the two-color color thermal printing medium is faster than the transport speed when printing the second color. Since the paper is transported, the printing efficiency is improved, and the printing time can be reduced.

According to a second aspect of the present invention, a first color which develops when the first printing energy is applied and a second color which develops when the second printing energy larger than the first printing energy is applied. The thermal head is moved relative to the two-color thermal printing medium having two-color developing characteristics of two colors, and each resistance heating element of the thermal head is selectively driven with respect to the two-color thermal printing medium. In the thermal printer that performs dot printing by applying the first or second printing energy, the first printing energy is applied to cause the two-color developing thermal printing medium to develop the first color. And the case where the second printing energy is applied in order to cause the two-color coloring thermal printing medium to develop the second color, the two-color coloring sensitivity depends on the amount of printing energy. The conveying speed of the print medium so as to variably.

Therefore, the first printing energy is applied to the two-color thermal printing medium to produce the first color, and the second printing energy is applied to the two-color thermal printing medium to produce the second color. When the printing energy is applied, the transport speed of the two-color developing thermal printing medium is changed according to the amount of printing energy, so that, for example, the second printing energy at which the second color develops When printing the first color, which develops color when the first printing energy, which has a smaller energy amount, is applied, the two-color thermal printing medium is transported at a speed higher than the transport speed when printing the second color. Therefore, the printing efficiency is improved and the printing time can be shortened.

[0011] The invention according to claim 3 is the invention according to claim 1 or 2.
In the thermal printer described above, the transport speed of the two-color developing thermal printing medium is made variable in accordance with an energizing pulse width that changes based on the temperature of the thermal head even when printing the same color.

Therefore, even when the transfer speed of the two-color developing thermal printing medium is the same color printing, the printing speed can be varied according to the energizing pulse width which changes based on the temperature of the thermal head. Even if is printed, if the thermal head is at a high temperature, the energization pulse width becomes short, so that the transport speed can be further increased.

The invention described in claim 4 is the first to third aspects of the present invention.
In the thermal printer according to any one of the above, when printing commands of the first color and the second color are mixed in one line, the two-color-developed thermal printing is performed at a conveying speed having a longer energizing pulse width. Set the print medium transport speed.

Therefore, when printing commands of the first color and the second color are mixed in one line, the conveying speed of the two-color developing thermal printing medium is set to the conveying speed having the longer energizing pulse width. This ensures that the two-color heat-sensitive printing medium is not conveyed at a high speed during the printing of the second color, so that the printing is reliably executed.

[0015]

FIG. 1 shows a first embodiment of the present invention.
This will be described with reference to FIG. The thermal printer according to the present embodiment is a receipt printer built in a POS terminal or an ECR, and has two colors of blue (first color) and black (second color) due to the characteristics described in FIG. This is an example of application to a thermal printer using two-color heat-sensitive paper as a two-color heat-sensitive printing medium capable of printing.

FIG. 1 is a longitudinal sectional side view schematically showing the structure of the receipt printer 1, and FIG. 2 is an external perspective view thereof. The receipt printer 1 includes a printer main body 2 having a housing structure with an open top and a printer cover 3. The printer cover 3 is openable and closable about the support shaft 4 with respect to the printer main body 2. The printer body 2 is provided with a platen 5 having a roller structure and an arc-shaped paper storage unit 6.
The paper storage section 6 stores and holds receipt paper 7 which is a roll-shaped two-color-developed thermal paper. On the other hand, on the printer cover 3 side, a line-type thermal head 9 which is in contact with the platen 5 and constitutes the printing unit 8 is provided. Thus, when the printer cover 3 is closed, the transport path 1 that leads from the paper storage unit 6 to the paper discharge side via the printing unit 8
0 is formed, and the thermal head 9 can be brought into contact with the platen 5 with a predetermined pressure through the transport path 10.

Here, the thermal head 9 is mounted on the platen 5
A large number of resistance heating elements are arranged in a line in a line direction (a direction orthogonal to the conveyance direction of the receipt paper 7) at a portion facing and contacting the sheet. Although the details will be described later, in such a thermal head 9, the specification of the head resistance value of these resistance heating elements can be selected according to the specification of a POS terminal or the like to which the head is applied.

Further, a cutter mechanism 11 is provided at a discharge side exit of the transport path 10. This cutter mechanism 11
Has a structure in which a fixed blade 12 and a movable blade 13 are combined, both of which are in the shape of a long flat plate. The movable blade 13 slides on the fixed blade 12 to cut the receipt paper 7 conveyed along the conveyance path 10. belongs to. Note that the fixed blade 12 is provided on the printer cover 3 side, and the movable blade 13 has a separated type structure provided on the printer main body 2 side.

Next, the electrical connection of each part built in the receipt printer 1 will be described with reference to FIG. FIG.
As shown in (1), the receipt printer 1 is provided with a CPU 14 that performs overall control. This CPU 14
The thermal head 9 is connected to the I / O port. The thermal head 9 includes a clock (CLK), data (DATA) and a strobe (S
TROBE) is driven based on each signal. A thermistor 15 is attached to a head substrate (not shown) of the thermal head 9, and a detection signal (head temperature information) from the thermistor 15 is converted into a digital value through an A / D converter 16 as an I / O signal of the CPU 14. It is connected so as to be taken into the / O port.

The CPU 14 is connected to a ROM 17 and a RAM 1 via bus lines such as a data bus and an address bus.
8 and a character generator ROM 19 are connected. The ROM 17 stores fixed data, and the RAM 18 temporarily stores rewritable variable data.

FIG. 4 is an explanatory diagram showing a storage area in the ROM 17. As shown in FIG. As shown in FIG. 4, a ROM 17 stores a program storage area 1 for storing a control program.
7a, a table for storing a head resistance rank table 20 of the thermal head 9 (see FIG. 5) and other storage areas 17b, and a head energization table 17c for each thermistor value
Is stored in the head energization table storage area 17d for each thermistor value, which stores the data for each head resistance value rank.

FIG. 5 shows a head resistance rank table 20.
FIG. As shown in FIG. 5, the head resistance value rank table 20 stored in the table or other storage area 17b prepares a range of head resistance values in 16 ranks from 1 to 16. Which head resistance value rank is used is preset by a jumper (not shown).

The thermistor-value-based head energizing table 17c of the ROM 17 indicates that the energizing pulse widths of two colors (black and blue) to the resistance heating element of the thermal head 9 corresponding to the temperature information detected by the thermistor 15 are set in advance. The tables are set and 16 levels of head resistance ranks 1 to 16 are prepared. Here, FIG.
Next, an example of the setting contents of the head energization table 17c classified by thermistor value of rank 1 is schematically exemplified. Each energization width data of the black energization pulse width and the blue energization pulse width set for each head temperature range shown in the temperature ranks 0 to F is set so as to be inversely proportional to the head temperature. With this setting, unevenness in print density due to temperature fluctuation of the thermal head 9 is less likely to occur.

Next, the RAM 18 will be described. Here, FIG. 6 is an explanatory diagram showing a storage area in the RAM 18. As shown in FIG. 6, the RAM 18 has an area 18a for developing a head energizing table 17c for each thermistor value corresponding to the head resistance value rank of the thermal head 9, a receiving buffer 18b for temporarily storing received print data, and a receiving buffer 18b. An edit buffer 18c for dot development of print data stored in the print data 18b, a pointer area 18d, a flag area 18e, and the like are secured. For example, as shown in FIG. 7, the print data transmitted from the host device or the like and temporarily stored in the reception buffer 18b includes one-line print data 21 composed of a character code or the like,
Print command 2 specifying that 1 is print data
2. Character attribute code 23 indicating color information of print data,
It is constituted by a line end code 24 indicating the end of the print data.

As shown in FIG. 3, a receipt motor 25 for driving the platen 5 and transporting the receipt paper 7 is connected to the CPU 14 via a driver IC 26, and the movable blade 13 of the cutter mechanism 11 is connected to the CPU 14. A cutter motor 27 for driving and cutting the receipt paper 7 is connected via a driver IC 28.

Next, the function executed by the CPU 14 by the control program stored in the ROM 17 will be described. FIG. 8 is a flowchart schematically showing the flow of the printing process. As shown in FIG. 8, when the power is turned on (Y in step S1), the head resistance rank of the thermal head 9 set by the jumper is read to determine the head rank (step S2).
Head energization table storage area 17d for each thermistor value
Then, the head energizing table 17c according to the thermistor value of the corresponding head rank is developed and set in the thermistor value energizing table developing area 18a of the RAM 18 (step S3), and the head is moved by the thermistor 15 attached to the head substrate of the thermal head 9. Detect temperature and RA
A black and blue energizing pulse corresponding to the temperature rank including the head temperature detected by the thermistor 15 with reference to the thermistor value-specific head energizing table 17c set in the thermistor value-specific head energizing table development area 18a of M18. Read each width (Step S
4).

In this state, for example, the printer waits for transmission of a print command from the host device or the like (step S5), and when print data as shown in FIG. 7 is transmitted as the print command (Y in step S5). ), And proceed to step S6. In step S6, the transmitted print data is temporarily stored in the reception buffer 18b, and then the one-line print data 21 of the print data is dot-developed in the edit buffer 18c with reference to the character generator ROM 19.

Next, it is determined based on the character attribute code 23 in the print data whether the print color of the print data is black or blue on the receipt paper 7 which is a two-colored thermal paper (step S7). .

The dot-expanded 1 in the edit buffer 18c
If the print color of the line print data 21 is black (Y in step S7), the receipt motor 25 for transporting the receipt paper 7 is driven up to X (pulses / sec) (step S8). On the other hand, if the print color of the one-line print data 21 dot-developed in the edit buffer 18c is blue (N in step S7), the receipt motor 25 for transporting the receipt paper 7 is set to Y (pulse / second). Slow-up driving is performed until (step S9). As described with reference to FIG. 11, the printing energy E for printing in blue
1 (approximately 0.20 (mj / dot)) is about half of the printing energy E2 (approximately 0.40 (mj / dot)) when printing in black, so that the motor pulse rate set in this case is The relationship between X and Y is as follows: Y = (1.5-2.0) × X. In other words, the receipt paper 7 is conveyed at a higher speed when printing in blue than when printing in black.

Then, in conjunction with the slow-up drive of the receipt motor 25 in step S8 or S9, the black or blue energizing pulse width read in step S4 is used as the head strobe time to set the thermal head 9 corresponding to the print dot.
, The black or blue printing on the receipt paper 7 is executed (step S1).
0).

When printing of one line is completed, the editing buffer 18c is cleared, and the receipt motor 25 is driven down slowly (step S11).
The process returns to step 5 and waits for transmission of a print command again.

Here, the transfer speed of the receipt paper 7 is varied in accordance with the color of the receipt paper 7 which is a two-color heat-sensitive thermal paper having a different amount of energy required for coloring, so that, for example, black color is generated. In the case of printing a blue color that develops when the first printing energy E1 having a smaller energy amount than the second printing energy E2 is applied, the receipt paper 7 has a higher speed than the transport speed during black printing.
Can be conveyed, so that printing efficiency can be improved and printing time can be shortened.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those described in the first embodiment of the present invention are denoted by the same reference numerals, and description thereof will be omitted. This embodiment is different from the first embodiment in that the control program stored in the ROM 17 is
The function of the printing process to be executed by U14 is different.

FIG. 9 is a flowchart schematically showing the flow of the printing process. As shown in FIG. 9, when the power is turned on (Y in step S21), the head resistance rank of the thermal head 9 set by the jumper is read to determine the head rank (step S2).
2) The head energizing table 17c by thermistor value of the corresponding head rank is expanded and set in the thermistor value energizing table developing area 18a of the RAM 18 from the thermistor value energizing table storage area 17d of the ROM 17 (step S23). The head temperature is detected by the thermistor 15 attached to the head substrate of the thermal head 9, and the thermistor 1 is referred to by referring to the thermistor-value-based head energization table 17 c set in the thermistor-value-based head energization table development area 18 a of the RAM 18.
The energizing pulse widths of black and blue corresponding to the temperature rank including the head temperature detected in step 5 are read (step S24).

In this state, for example, the printer waits for transmission of a print command from the host device or the like (step S25), and when print data as shown in FIG. 7 is transmitted as the print command (Y in step S25). ), And proceed to step S26. In step S26, the transmitted print data is temporarily stored in the reception buffer 18b, and then the 1-byte print data is referred to by referring to the ROM 19 for the character generator.
The line print data 21 is developed into dots in the edit buffer 18c.

Next, it is determined based on the character attribute code 23 in the print data whether the print color of the print data is black or blue on the receipt paper 7 which is a two-colored thermal paper (step S27). .

The dot-expanded 1 in the edit buffer 18c
If the print color of the line print data 21 is black (Y in step S27), the head temperature detected by the thermistor 15 is included in the temperature rank of 0-5,
Whether it is included in the temperature rank of B or in the temperature ranks of C to F is determined in steps S28 to S29. If the head temperature detected by the thermistor 15 is included in the temperature rank of 0 to 5 (Y in step S28), the receipt motor 25 for conveying the receipt paper 7 is slowed up to X (pulses / second). It is driven (step S30), and if the head temperature detected by the thermistor 15 is included in the temperature rank of 6 to B (Y in step S29), the receipt motor 25 is turned on.
(Pulse / sec) (Step S3
1) When the head temperature detected by the thermistor 15 is C
ＦF are included in the temperature rank (step S
29, N), the receipt motor 25 is slowed down to Z (pulse / second) (step S32).

On the other hand, when the print color of the one-line print data 21 dot-developed in the edit buffer 18c is blue (N in step S27), the head temperature detected by the thermistor 15 is in the temperature rank of 0-5. Whether it is included, included in the temperature rank of 6 to B, or included in the temperature rank of C to F is determined in steps S33 to S34.
Is determined. If the head temperature detected by the thermistor 15 is included in the temperature rank of 0 to 5 (Y in step S33), the receipt motor 25 for transporting the receipt paper 7 is slowed up to U (pulse / second). It is driven (step S35), and if the head temperature detected by the thermistor 15 is included in the temperature rank of 6 to B (Y in step S34), the receipt motor 25 is slowed up to V (pulse / second). Then, if the head temperature detected by the thermistor 15 is included in the temperature ranks C to F (N in step S34), the receipt motor 25 is set to W (pulses / second).
Slow-up drive is performed until (step S37). The motor pulse rates U, V, W,
The relationship among X, Y, and Z is as follows: W>V>U>Z>Y> X. In other words, the receipt paper 7 is conveyed at a higher speed when printing in blue than when printing in black, and even when printing in the same color, the receipt paper 7 is changed according to the energizing pulse width that changes based on the head temperature. The transfer speed of the receipt paper 7 is variable.

In addition to the slow-up driving of the receipt motor 25 in steps S30 to S32 or S35 to S37, the black or blue energizing pulse width read in step S14 is used as the head strobe time to set the thermal head 9 corresponding to the print dot. By driving the resistance heating element, black or blue printing is performed on the receipt paper 7 (step S38).

When printing of one line is completed, the editing buffer 18c is cleared, and the receipt motor 25 is driven down slowly (step S39).
The process returns to step 35 and waits for transmission of a print command again.

Here, even when printing the same color, the same color can be printed by changing the conveyance speed of the receipt paper 7 in accordance with the energizing pulse width which changes based on the temperature of the thermal head 9. Even in the case of printing, if the temperature of the thermal head 9 is high, the energizing pulse width becomes short, so that the transport speed of the receipt paper 7 can be further increased.

Next, a third embodiment of the present invention will be described with reference to FIG.
It will be described based on. The same parts as those described in the first embodiment of the present invention are denoted by the same reference numerals, and description thereof will be omitted. This embodiment is different from the first embodiment in that the control program stored in the ROM 17 is C
The function of the printing process executed by the PU 14 is different. In the present embodiment, a case will be described in which data of two colors of blue and black are mixed in one line.

FIG. 10 is a flowchart schematically showing the flow of the printing process. As shown in FIG.
When the power is turned on (Y in step S41), the head resistance value rank of the thermal head 9 set by the jumper is read to determine the head rank (step S4).
2) The head energizing table 17c according to the thermistor value of the corresponding head rank is expanded and set in the thermistor value energizing table developing area 18a of the RAM 18 from the thermistor value energizing table storage area 17d of the ROM 17 (step S43). The head temperature is detected by the thermistor 15 attached to the head substrate of the thermal head 9, and the thermistor 1 is referred to by referring to the thermistor-value-based head energization table 17 c set in the thermistor-value-based head energization table development area 18 a of the RAM 18.
The energizing pulse widths of black and blue corresponding to the temperature rank including the head temperature detected in step 5 are read (step S44).

In this state, for example, the printer waits for transmission of a print command from the host device or the like (step S45). When print data as shown in FIG. 7 is transmitted as the print command (Y in step S45). ), And proceed to step S46. In step S46, the pulse rate of the receipt motor 25 for conveying the receipt paper 7 is set to Y (pulses / second).

Subsequently, after temporarily storing the transmitted print data in the reception buffer 18b, the one-line print data 21 of the print data is dot-developed in the edit buffer 18c with reference to the character generator ROM 19 (step S47). ).

Next, it is determined based on the character attribute code 23 in the print data whether or not the receipt paper 7, which is a two-color-developing thermal paper, exists in the print colors of the print data (step S48).

The dot-expanded 1 in the editing buffer 18c
If the print color of the line print data 21 is black (Y in step S48), the pulse rate of the receipt motor 25 for conveying the receipt paper 7 is set to X (pulse / second) (step S49). Proceed to step S50. As described with reference to FIG. 11, the printing energy E1 (about 0.20 (mj / dot)) for printing in blue is the printing energy E2 (about 0.40 (mj / do) for printing in black.
Since t) is about half, the relationship between the motor pulse rates X and Y set in this case is Y = (1.5-2.0) × X. In other words, when there is black in the receipt paper 7, which is a two-color-developed thermal paper, in the print color of the print data,
Even in the case of printing in blue, the receipt paper 7 is conveyed at the same low conveyance speed as in the case of printing in black.

On the other hand, if the print color of the one-line print data 21 dot-developed in the edit buffer 18c is not black (N in step S48), the process proceeds to step S50.

In step S50, the receipt motor 25 for transporting the receipt paper 7 is slowed up based on the set pulse rate. And
At the same time as the slow-up driving of the receipt motor 25 in step S50, the resistance heating element of the thermal head 9 corresponding to the print dot is driven by using the black or blue energizing pulse width read in step S4 as the head strobe time, thereby receiving the receipt. Black or blue printing is performed on the paper 7 (step S51).

When printing for one line is completed, the editing buffer 18c is cleared, and the process returns to step S45 to wait again for transmission of a print command.

Here, in the case where blue and black print commands are mixed in one line, the transfer speed of the receipt paper 7 is set to the transfer speed having the longer energization pulse width, so that the receipt is performed when printing in blue. Since the paper 7 is not transported at a high speed, printing can be executed reliably.

In each of the embodiments, the color developed by the two-color thermal paper is a combination of blue and black. However, the present invention is not limited to this, and a combination of red and black may be used. good.

[0053]

According to the first aspect of the present invention, the transfer speed of the two-color heat-sensitive thermal print medium is changed according to the color of the two-color heat-sensitive thermal print medium. When printing the first color that develops when the first printing energy with a smaller energy amount is applied compared to the second printing energy at which the color develops, the transport speed at the time of printing the second color Since the two-color heat-sensitive printing medium can be conveyed at high speed, printing efficiency can be improved and printing time can be shortened.

According to the second aspect of the present invention, the case where the first printing energy is applied to develop the first color on the two-colored thermal printing medium and the case where the second color is applied to the two-colored thermal printing medium In the case where the second printing energy is applied in order to form a color, the transport speed of the two-color heat-sensitive printing medium is changed according to the amount of the printing energy, for example, the second color is formed. When printing the first color which is colored when the first printing energy having a smaller energy amount than the second printing energy is applied, the printing speed is higher than the transport speed at the time of printing the second color. Because it is possible to transport color-sensitive thermal printing media, printing efficiency is improved,
Printing time can be reduced.

According to the third aspect of the present invention, in the thermal printer according to the first or second aspect, even when printing the same color, the transport speed of the two-color thermal printing medium is determined based on the temperature of the thermal head. Because the width of the energizing pulse is variable according to the changing energizing pulse width, the energizing pulse width becomes shorter if the thermal head is at a high temperature even when printing the same color. Can be.

According to a fourth aspect of the present invention, in the thermal printer according to any one of the first to third aspects,
When the print commands of the first color and the second color are mixed in one line, the transfer speed of the two-color developing thermal printing medium is set by setting the transfer speed of the longer energization pulse width to the second transfer speed. Since the two-color heat-sensitive thermal print medium is not transported at a high speed during the printing of the color, the printing can be executed reliably.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view schematically showing the structure of a receipt printer according to a first embodiment of the present invention.

FIG. 2 is an external perspective view thereof.

FIG. 3 is a block diagram showing an electrical connection of each unit built in the receipt printer.

FIG. 4 is an explanatory diagram showing a storage area in a ROM.

FIG. 5 is an explanatory diagram showing a head resistance value rank table.

FIG. 6 is an explanatory diagram showing a storage area in a RAM.

FIG. 7 is an explanatory diagram showing a data structure of print data.

FIG. 8 is a flowchart schematically showing a flow of a printing process.

FIG. 9 is a flowchart schematically showing a flow of a printing process according to the second embodiment of the present invention.

FIG. 10 is a flowchart schematically showing a flow of a printing process according to a third embodiment of the present invention.

FIG. 11 is a graph showing the coloring characteristics of a two-colored thermal paper.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal printer 7 Two-color thermal printing medium 9 Thermal head E1 First printing energy E2 Second printing energy

Continuing on the front page (72) Inventor Katsumune Hayashi 570, Ohito, Oni-cho, Tagata-gun, Shizuoka Toshiba Tec Co., Ltd. F-term in the Ohito Plant (reference) 2C066 AA01 AA03 AB09 AD01

Claims (4)

[Claims] 1. A two-color developing property by applying a first printing energy for forming a first color and a second printing energy larger than the first printing energy for forming a second color. The thermal printing head and the thermal head are moved relative to each other, and the resistance heating elements of the thermal head are selectively driven with respect to the thermal printing medium to apply the first or second printing energy. A thermal printer which performs dot printing by performing the above-mentioned operation, wherein the transport speed of the two-color heat-sensitive thermal print medium is changed according to the color of the two-color heat-sensitive thermal print medium. 2. A first color that develops when a first printing energy is applied, and a second color that develops when a second printing energy that is larger than the first printing energy is applied. The two-color heat-sensitive thermal print medium having the color-developing characteristics and the thermal head are relatively moved to selectively drive each of the resistive heating elements of the thermal head with respect to the two-color heat-sensitive thermal print medium, and the first or the second heat-sensitive thermal print medium is selectively driven. In a thermal printer that performs dot printing by applying a second printing energy, a case where the first printing energy is applied in order to develop the first color on the two-color developing thermal printing medium, and a case where the two colors are applied. In the case where the second printing energy is applied in order to develop the second color on the coloring and thermal printing medium, the conveying speed of the two-color developing and thermal printing medium according to the amount of printing energy Thermal printer characterized in that as variable. 3. The method according to claim 2, wherein the conveying speed of the two-color-developing thermal printing medium is varied in accordance with an energizing pulse width that changes based on the temperature of the thermal head even when printing the same color. The thermal printer according to claim 1 or 2, wherein 4. The printing speed of the two-color-developing thermal printing medium is set to a feeding speed having a longer energizing pulse width when printing commands of the first color and the second color are mixed in one line. The thermal printer according to any one of claims 1 to 3, wherein