JP2001293894A - Thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal printer which can execute high quality printing constantly on an arbitrary print medium having a different thermal diffusivity. SOLUTION: A thermal head 1 is abutted against a print medium 12 and moved by driving a carriage control section 4 (Step S1) and the heating section 1a of the thermal head 1 is conducted for a reference time by driving a conduction control section 2 (Step S2). An output signal is taken from a temperature detecting section 1b to a CPU 6 through an A/D converter (Step S3) and variation of the output from a thermistor is detected up to a set time (Step S4). Subsequently, difference between the output temperature of the thermistor and a reference temperature is determined and a conduction time corresponding to the temperature difference is read out from a table shown on Fig. 3 (Step S5). After a corrective conduction time read out from the table is set at the conduction control section 2 (Step 6), required printing is started by driving a print control section (Step S7).

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 method for calibrating a power-on time to a thermal head at the start of printing and always performing high-quality printing regardless of the type of printing medium. About the means.

[0002]

2. Description of the Related Art In a thermal printer, a thermal head is pressed against a print medium such as paper through an ink ribbon carrying a solid ink of a heat-soluble property on one side, and a heating element arranged on the thermal head is selectively applied. A desired mark such as a character, a symbol, or a figure is printed by transferring the solid ink that has been heated and melted to a print medium.

[0003] The density of a mark printed on a print medium is
In the case where solid inks having the same heat dissolution characteristics are used, the temperature of the heating element provided in the thermal head (in this specification, this is referred to as “thermal head temperature”) fluctuates, and the temperature of the thermal head increases. Since it fluctuates depending on the energizing time to the body and the thermal diffusivity of the print medium, in order to always perform high-quality printing regardless of the type of print medium, grasp the thermal diffusivity of the print medium used for printing. On the other hand, it is necessary to extend the energizing time to the heating element for a printing medium in which the temperature of the thermal head is unlikely to rise, and to shorten the energizing time to the heating element for a printing medium in which the temperature tends to increase.

Conventionally, as a technique for controlling the energizing time to the thermal head in accordance with the type of print medium, a thermal head having a temperature detecting unit is provided, and when printing on the print medium is performed, input means is used. While inputting the type of the print medium to be used, every time one line is printed, the data from the temperature detection unit is read, and the transport speed data of the print medium corresponding to the type of the input print medium and the detected temperature data and The energizing time data to the thermal head is
There has been proposed one that reads from the OM and sets the transport speed of the print medium and the time for energizing the thermal head.

According to the printer of this embodiment, the conveying speed of the print medium and the energizing time to the thermal head are adjusted each time one line is printed according to the type of print medium to be used. High quality printing can be performed for various types of print media.

[0006]

However, the technique according to the above-mentioned known example is designed to execute printing on a print medium.
Since it is necessary to input the type of print medium to be used, there is a disadvantage in that high-quality printing cannot be executed for unknown print media and print media other than print media registered in the ROM.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the deficiencies of the prior art, and provides a thermal printer capable of always performing high-quality printing on any print medium having a different thermal diffusivity. Is a technical issue.

[0008]

According to the present invention, there is provided a thermal printer having a thermal head provided with a heating section and a temperature detecting section.
The thermal head, an energization control unit that controls an energization time to the heating unit, a printing control unit that supplies print information to the heating unit, and a conveyance control unit that controls a relative operation of the thermal head with respect to a print medium. A main control unit that controls the control unit while taking in the output signal from the temperature detection unit to determine the thermal diffusivity of the print medium, before starting printing on the print medium, By operating the energization control unit and the conveyance control unit, the contact of the heating unit with the printing medium, the conveyance of the thermal head in a direction along the surface of the printing medium, and the energization of the heating unit for a reference time. The main control unit determines the thermal diffusivity of the print medium, and then determines the heat generation rate according to the determined thermal diffusivity of the print medium so as to perform optimal printing on the print medium. To the department Set the charging time, and the configuration of performing printing on the printing medium by operating the power supply controller and the transport controller and a print control unit.

Secondly, for a thermal printer having a heater block provided with a heating section and a temperature detecting section separately from the thermal head, the thermal head and the heater block and the power supply time to each heating section are controlled. Power supply control unit, a print control unit that supplies print information to a heat generation unit of the thermal head, a conveyance control unit that controls the relative operation of the thermal head and the heater block with respect to a print medium, and an output from the temperature detection unit. A main control unit that controls the control unit while taking a signal to determine the thermal diffusivity of the print medium, and before starting printing on the print medium, the power supply control unit and the transport control unit. Operating the heater block to contact the print medium, transport the heater block in a direction along the surface of the print medium, and By energizing the heat-generating portion provided in the lock for a reference time, the thermal diffusion rate of the print medium is determined by the main control, and thereafter, a determination is made so that optimal printing on the print medium can be performed. In accordance with the thermal diffusivity of the print medium, an energization time to the heat generating unit provided in the thermal head is set, and the energization control unit, the conveyance control unit, and the print control unit are operated to control the print medium. Printing was performed.

As described above, the thermal diffusivity of the print medium to be used is determined before printing on the print medium is started, and based on the result, the heat is supplied to the heat generating portion so that the optimum print can be performed on the print medium. When the time is set, optimum printing can be performed on the print medium to be used regardless of the magnitude of the thermal diffusivity, so that the types of print media that can be used can be increased without deteriorating the print quality. According to the first thermal printer, since the thermal head includes the heat generating portion and the temperature detecting portion, the printing means including the temperature detecting portion can be reduced in size and simplified, and the thermal printer can be downsized. And cost reduction can be achieved. On the other hand, according to the second thermal printer, since the heater block for detecting the temperature is provided separately from the thermal head, it is possible to use a normal type thermal head having no temperature detecting section, and to share parts. Can be achieved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a thermal printer according to the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing a configuration of a thermal printer according to the embodiment, FIG. 2 is a side view of a thermal head provided in the thermal printer according to the embodiment, and FIG. 3 is a thermal diffusivity of a print medium. FIG. 4 is a flow chart showing a printing operation of the thermal printer according to the embodiment of the present invention, and FIG. 5 is a flow chart showing a printing operation of the thermal printer according to the present embodiment with respect to a sensing result, and FIG. FIG. 6 is a graph showing the relationship between the temperature of the thermal head detected by the temperature detection unit after a predetermined time from the start of energization (this temperature is referred to as “thermistor output temperature” in this specification) and the thermal diffusivity of the print medium. FIG. 4 is a graph showing the relationship between the thermistor output temperature and print density.

As shown in FIG. 1, a thermal printer according to the present embodiment includes a thermal head 1 having a heating section 1a and a temperature detecting section (thermistor) 1b,
a control unit 2 for controlling the power supply time to the heating unit 1a, a print control unit 3 for supplying print information to the heating unit 1a, a transfer control unit 4 for the thermal head 1, and an output signal from the temperature detection unit 1b. A / D converter 5 for A / D-converting the data, and a main control unit which takes in the output signal of the A / D converter 5 to determine the thermal diffusivity of the print medium and control the control units 2, 3, and 4. (CPU) 6 and a memory (ROM) 7 in which required data and programs are stored in advance.

The thermal head 1 is mounted on a carriage (not shown), and the transfer control unit 4 controls the printing position shown in FIG. 2B where the heating unit 1a contacts the print medium 12 via the ink ribbon 11; The heat generating portion 1 a is reciprocated between the print medium 12 and the standby position shown in FIG. 2A and is reciprocated along the surface of the print medium 12 within the width of the print medium 12. Note that the configuration of the carriage is a matter belonging to the public domain and is not the gist of the present invention, and therefore, the description thereof is omitted. The heating section 1a is provided with one or more heating elements (not shown), and the energization time to the heating elements is controlled by the energization control section 2 and the print data for the heating elements is controlled. The supply is controlled by the print control unit 3.

The power-on time control table shown in FIG. 3 is stored in the ROM 7. This table shows that the ambient temperature is 0
℃, 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃
In each of the cases (1) to (2), a heat is applied to the heat-generating portion 1a necessary for performing printing at an optimum density on a print medium having a reference thermal diffusivity (in this specification, this is referred to as a "reference medium"). Energizing time (this is referred to as “reference time” in this specification) T (0), T (10), T (2
0), T (30), T (40), T (50), T (6
0) ... and the environmental temperature is 0 ° C, 10 ° C, 20 ° C, 30
.., 40 ° C., 50 ° C., 60 ° C...., The heating unit 1a is energized for the reference time, and the thermistor output temperature measured for the reference medium is set as a reference value. The difference is + 1 ° C, + 2 ° C, ...,-
An energizing time to the heat generating portion 1a required to print an optimal density on a print medium at 1 ° C., −2 ° C.,... (This is referred to as “corrected energizing time”) T ( −
1), T (−2),..., T (+1), T (+2) ·
・ ・ Is displayed. The correction energization time is longer on the left side of the table in FIG. 3 and on the upper side. In the example of FIG. 3, the environmental temperatures are 0 ° C., 10 ° C., 20 ° C., 30 ° C.,
Although only the reference time and the correction energizing time at 0 ° C., 50 ° C., 60 ° C.... Are listed, the environmental temperature is set at a finer temperature interval, for example, every 1 ° C. Of course, it is also possible to raise the reference time and the correction energizing time.

The ink ribbon 11 has a heat-soluble solid ink carried on one surface of a base film, and is disposed between the thermal head 1 and the print medium 12 with the solid ink carrying surface facing the print medium 12. Is done. In the case where the ink ribbon 11 carrying the solid ink having the same heat melting property is used and the power supply time to the heat generating portion 1a is fixed, as shown in FIG. The density (print density) OD increases as the thermistor output temperature increases. The thermistor output temperature is
As shown in FIG. 5, the temperature varies depending on the thermal diffusivity of the print medium 12, and increases as the thermal diffusivity of the print medium 12 decreases.

The operation of the thermal printer according to this embodiment will be described below with reference to the flowchart of FIG. This program is stored in the ROM 7.

First, the transport controller 4 is driven to bring the thermal head 1 into contact with the print medium 12 via the ink ribbon 11 and to transport the thermal head 1 at a predetermined speed along the surface of the print medium 12 (procedure). S1). Next, the energization control unit 2 is driven to energize the heating unit 1a of the thermal head 1 for a reference time (step S2). Simultaneously with the start of energization, an output signal from the temperature detector 1b is taken into the CPU 6 via the A / D converter 5 (step S3), and a change in the thermistor output until a set time is detected (step S4).
Thereby, the data of FIG. 5 is obtained. Then, CP
U6 finds the difference between the thermistor output temperature and the reference temperature, and reads the energization time corresponding to the temperature difference from the table of FIG. 3 (step S5). For example, when the ambient temperature is 20 ° C. and the thermistor output temperature is 2 ° C. lower than the reference temperature, the correction energization time T (22) longer than the reference value energization time T (20) is read from the table of FIG. When the output temperature is higher than the reference temperature by 2 ° C., a corrected energization time T (18) shorter than the energization time T (20) of the reference value is read from the table of FIG. Next, after setting the corrected energization time read from the table in the energization control unit 2 (procedure S
6) The print controller 3 is driven to start required printing (step S7). These operations are performed based on a command from the CPU 6.

As shown in FIG. 6, when the thermal diffusivity of the printing medium is higher than the reference value, when the heating section 1a is energized for the reference time, the output temperature of the thermistor becomes lower than the reference value and the printing density becomes lower. Conversely, when the heat diffusion rate of the print medium is lower than the reference value and the heating unit 1a is energized for the reference time, the thermistor output temperature becomes higher than the reference value and the print density increases. descend. Like,
When the power supply time to the heat generating portion 1a is fixed, the print quality varies depending on the thermal diffusivity of the print medium. On the contrary,
The thermal printer according to the present embodiment determines the thermal diffusivity of the print medium 12 prior to the start of printing, and changes the energization time to the heating unit 1a so as to perform optimal printing. , You can always perform high quality printing. In addition, since the thermal diffusivity of the print medium 12 is determined for each print, it is not necessary to specify the type of print medium to be used in advance, which is convenient to use and can increase the types of print media that can be used. . Further, since the heat generating portion 1a and the temperature detecting portion 1b are provided in the thermal head 1, the configuration around the head can be reduced and simplified, and the size and cost of the thermal printer can be reduced.

In the above-described embodiment, the thermal head 1 having the temperature detecting portion 1b is used. However, instead of such a configuration, a thermal head having no thermistor, a heater 21 and a thermistor 22 shown in FIG. Before starting the printing operation using the thermal head by setting the heater block 23 having
By using the heater block 23, the thermal diffusivity of the print medium can be determined. In this case, the same effects as those of the thermal printer according to the embodiment can be achieved, and since a heater block for temperature detection is provided separately from the thermal head, a normal type thermal head without a temperature detection unit can be used. It can be used and parts can be shared.

Further, in the above-described embodiment, a change in the thermistor output up to the set time is detected (step S4 in FIG. 4). Can also be determined.

[0021]

According to the first aspect of the present invention, prior to the start of printing, the thermal diffusivity of the print medium is determined, and the energization time for the heat generating portion is changed so that optimum printing can be performed. Regardless of this, high quality printing can always be performed. In addition, since the thermal diffusivity of the print medium is determined for each print, it is not necessary to specify the type of print medium to be used in advance, so that the use is convenient and the types of print media that can be used can be increased. Further, since the heat generating section and the temperature detecting section are provided in the thermal head, the configuration around the head can be reduced and simplified, and the thermal printer can be reduced in size and cost.

According to the second aspect of the present invention, prior to the start of printing, the thermal diffusivity of the print medium is determined, and the energization time for the heat generating portion is changed so that optimum printing can be performed. And high quality printing can always be performed. In addition, since the thermal diffusivity of the print medium is determined for each print, it is not necessary to specify the type of print medium to be used in advance, so that the use is convenient and the types of print media that can be used can be increased. Further, since the heater block for detecting the temperature is provided separately from the thermal head, a normal-type thermal head having no temperature detecting section can be used, and the components can be shared.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a thermal printer according to an embodiment.

FIG. 2 is a side view of a thermal head provided in the thermal printer according to the embodiment in a use state.

FIG. 3 is a table illustrating an energization time control table according to a thermal dissolution characteristic of an ink ribbon with respect to a thermal diffusivity sensing result of a print medium.

FIG. 4 is a flowchart illustrating a printing operation of the thermal printer according to the embodiment.

FIG. 5 is a graph showing a relationship between the thermistor output temperature and the thermal diffusivity of a print medium when the power supply time to the heating element is constant.

FIG. 6 is a graph showing the relationship between the thermistor output temperature and print density.

FIG. 7 is a configuration diagram of a heater block.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal head 1a Heat generation part 1b Temperature detection part (thermistor) 2 Current supply control part 3 Print control part 4 Transport control part 5 A / D converter 6 Main control part (CPU) 7 Memory (ROM) 11 Ink ribbon 12 Print medium 21 Heater 22 Thermistor 23 Heater block

Claims (2)

[Claims] A thermal head having a heating unit and a temperature detection unit; an energization control unit for controlling an energization time to the heating unit; a printing control unit for supplying print information to the heating unit;
A transport control unit that controls the relative operation of the thermal head with respect to a print medium, and a main control unit that controls the control units while taking in an output signal from the temperature detection unit to determine a thermal diffusivity of the print medium. Before starting printing on the print medium, operating the energization control unit and the conveyance control unit to contact the heating unit to the print medium and the direction along the surface of the print medium. The main control unit determines the thermal diffusivity of the print medium by carrying the thermal head and energizing the heat generating unit for a reference time, and then performing optimal printing on the print medium. According to the determined thermal diffusivity of the print medium, setting the energization time to the heating unit, operating the energization control unit, the transport control unit, and the print control unit to perform printing on the print medium. Special Thermal printer to be. 2. A thermal head having a heat generating section, a heater block having a heat generating section and a temperature detecting section, an energizing control section for controlling an energizing time to each of the heat generating sections, and a heat generating section of the thermal head. A print control unit that supplies print information;
A transport control unit that controls the relative operation of the thermal head and the heater block with respect to a print medium, and a main control unit that fetches an output signal from the temperature detection unit to determine a thermal diffusivity of the print medium and controls each of the control units. A control unit, before starting printing on the print medium, operating the energization control unit and the conveyance control unit to contact the heater block with the print medium and a direction along the surface of the print medium. The main control unit determines the thermal diffusivity of the print medium by carrying the heater block to the heater block and energizing the heating unit provided in the heater block for a reference time. In accordance with the determined thermal diffusivity of the print medium, an energizing time to the heat generating portion provided in the thermal head is set so that an optimal print can be performed on the medium. Thermal printer and performing printing on the printing medium part and the conveyance control unit and by operating the print control unit.