JP2017074799A - Thermal printer and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal printer and a computer program which can suppress deterioration in printing quality.SOLUTION: A thermal printer includes a plurality of heating elements, a printing control part and a printing part. The heating elements generate heat by application of electric power. The printing control part applies first electric power to the heating elements which are not used for printing on an area composed of a plurality of pixels continuing in one line of printing data, of the plurality of heating elements, applies second electric power higher than the first electric power to heating elements which are used for printing, of the plurality of heating elements, and determines the first electric power and the second electric power so that total electric power indicating the total of the electric power applied to the plurality of heating elements becomes constant. The printing part performs printing using the plurality of heating elements.SELECTED DRAWING: Figure 4

Description

  Embodiments described herein relate generally to a thermal printer and a computer program.

Conventionally, in a thermal printer, printing is performed by heating a heating element by applying a voltage to a plurality of heating elements built in a thermal head and using the heat of the heated heating element. Such a printing method is called a thermal transfer method or a thermal method. Conventionally, in these printing methods, the power applied to the heating element is adjusted in accordance with changes in the environmental temperature, the pattern to be printed, the printing speed, etc., and the device has been devised to maintain as constant print quality as possible under any use conditions. .
However, depending on the use conditions, transient printing instability may be noticeable during printing, particularly at the start of printing. For this reason, there is a case where the printing quality is deteriorated due to the state where printing cannot be performed or printing failure (for example, fading) continues until printing is stabilized.

JP-A-7-81108 Japanese Patent Laid-Open No. 9-314886 Japanese Patent Laid-Open No. 10-181069 JP 2006-116952 A

  The problem to be solved by the present invention is to provide a thermal printer and a computer program that can suppress a decrease in print quality.

The thermal printer of the embodiment includes a plurality of heating elements, a print control unit, and a printing unit.
The heating element generates heat when power is applied. The printing control unit applies first power to a heating element that is not used for printing in an area composed of a plurality of continuous pixels in one line of print data among the plurality of heating elements, and among the plurality of heating elements, The second power higher than the first power is applied to the heating elements used for printing, and the first power is constant so that the total power representing the total power applied to the plurality of heating elements is constant. And determining the second power. The printing unit performs printing using the plurality of heating elements.

1 is an external view of a configuration of a thermal printer 100 according to an embodiment. FIG. 2 is a side view illustrating an example of an internal configuration of the thermal printer 100 according to the embodiment. FIG. 2 is a side view illustrating an example of an internal configuration of the thermal printer 100 according to the embodiment. FIG. 2 is a schematic block diagram illustrating a functional configuration of a control device 400. The figure which shows the specific example of S electric power value information table. The figure which shows the specific example of S temperature and S stop electric power value information table. The schematic diagram inside the thermal head 6. FIG. 5 is a flowchart showing a processing flow of the thermal printer 100 in the present embodiment. The figure showing the comparison result of the conventional method and the method in this embodiment.

Hereinafter, a thermal printer and a computer program according to an embodiment will be described with reference to the drawings.
FIG. 1 is an external view of a configuration of a thermal printer 100 according to the embodiment.
The thermal printer 100 prints a predetermined image on a sheet and issues a sheet on which the image is printed. Label roll paper is used as an example of the sheet.
As shown in FIG. 1, the thermal printer 100 includes a display unit 200, an operation unit 300, and a discharge port 350.

The display unit 200 is an image display device such as a liquid crystal display or an organic EL (Electro Luminescence) display. The display unit 200 operates as an output interface and displays characters and images. Further, the display unit 200 may operate as an input interface and receive an instruction input from the user.
The operation unit 300 is configured using an existing input device such as a button. The operation unit 300 is operated by the user when inputting a user instruction to the thermal printer 100. For example, the operation unit 300 receives an input of a print start instruction.
The discharge port 350 discharges a sheet on which an image is printed.

  2 and 3 are side views showing an example of the internal configuration of the thermal printer 100 according to the embodiment. 2 and 3 are views of the internal configuration of the thermal printer 100 as seen from different sides. As shown in FIGS. 2 and 3, the thermal printer 100 includes a first chamber S1 and a second chamber S2 in the housing. The first chamber S1 and the second chamber S2 are separated by a vertical wall a1. First, the configuration in the first chamber S1 will be described with reference to FIG.

In the first chamber S1, a sheet 1, an ink ribbon 3, a supply shaft 4 for the ink ribbon 3, a take-up shaft 5 for the ink ribbon 3, a thermal head 6, a pinch roller P, a transport roller R, and a platen roller PR are provided. .
The sheet 1 is a strip-shaped sheet. The sheet 1 forms a roll portion 2 by being wound in a roll shape. The sheet 1 is conveyed from the roll unit 2 to the conveyance path 7.

Moreover, the sheet | seat shown as a continuous line in FIG. 2 has shown the sheet | seat 1 in the state where the diameter of the roll part 2 is comparatively large. On the other hand, an alternate long and short dash line L1 shown in FIG. 2 indicates the position of the sheet 1 in a state where the diameter of the roll portion 2 is relatively small. An arrow 1 </ b> A shown in FIG. 2 indicates the feeding direction of the sheet 1.
The ink ribbon 3 is a tape-like ink cartridge. The ink ribbon 3 is sandwiched between the thermal head 6 and the platen roller PR together with the sheet 1. The ink on the ink ribbon 3 is transferred to the sheet 1 by heat applied from the thermal head 6.

  The supply shaft 4 of the ink ribbon 3 is a shaft that feeds out the ink ribbon 3. The supply shaft 4 is provided on the delivery side of the ink ribbon 3. A roll portion 4 a of the ink ribbon 3 is set on the supply shaft 4. Hereinafter, the roll part 4a of the ink ribbon 3 is referred to as a ribbon roll. The supply shaft 4 is rotationally driven by a rotational drive mechanism including a DC motor, a gear, a belt, and the like.

  The take-up shaft 5 of the ink ribbon 3 is a shaft that takes up the ink ribbon 3. The winding shaft 5 is provided on the winding side of the ink ribbon 3. The winding shaft 5 is rotationally driven by a rotational driving mechanism including a DC motor, a gear, a belt, and the like. As the take-up shaft 5 rotates, the ink ribbon 3 is taken up by the take-up shaft 5 and pulled out from the ribbon roll.

The pinch roller P is disposed to face the conveyance roller R.
The conveyance roller R is driven by a motor (not shown) and conveys the sheet 1.
The platen roller PR is rotationally driven by a rotation drive mechanism (not shown) including a motor (not shown) such as a stepping motor, a gear, and a belt. The platen roller PR is arranged to face the thermal head 6 provided in the print head 6-1.

The print head 6-1 prints an image on a sheet. The print head 6-1 includes a thermal head 6. The print head 6-1 desirably includes an ambient temperature measurement sensor.
The thermal head 6 is disposed opposite to the platen roller PR above the platen roller PR. The thermal head 6 performs printing by using the ink ribbon 3 on the conveyed sheet or by using thermal paper without using the ink ribbon 3. When using thermal paper without using the ink ribbon 3, the thermal printer 100 may not include the ink ribbon 3. In the following description, a case where the thermal head 6 performs printing using the ink ribbon 3 will be described as an example. The thermal head 6 presses a sheet conveyed between the thermal head 6 and the platen roller PR against the platen roller PR. The thermal head 6 has a plurality of heating elements arranged in a row. The heating element generates heat when power is applied. The thermal head 6 heats the heating elements by selectively applying electric power to the plurality of heating elements.
The thermal head 6 performs printing by transferring the ink onto the sheet by melting or sublimating the ink on the ink ribbon 3 by the heat generated by the heating element. The thermal head 6 may be provided with a temperature sensor such as a thermistor. The temperature sensor is disposed at a position near the heating element in the center of the head and measures the temperature of the thermal head 6. Hereinafter, the temperature of the thermal head 6 is referred to as a head temperature.

In the following description, a mechanism including the thermal head 6, the ink ribbon 3, the supply shaft 4, the take-up shaft 5, the rotation drive mechanism, and the platen roller PR is referred to as a printing mechanism (printing unit). In the following description, a heating element used for printing among a plurality of heating elements is referred to as a printing use element, and a heating element not used for printing is referred to as a non-printing use element. For example, the remaining heating elements excluding the printing elements among the plurality of heating elements included in the thermal head 6 are non-printing elements. Here, in the following description, the printing-use element and the non-printing-use element are simply referred to as a heating element unless particularly distinguished.
The ambient temperature measurement sensor measures the temperature inside the thermal printer 100 at a position close to the thermal head 6 within a range not affected by the head temperature. Hereinafter, the temperature inside the thermal printer 100 is referred to as ambient temperature.

Next, the configuration in the second chamber S2 will be described with reference to FIG.
As shown in FIG. 3, the second chamber S2 includes a control device 400 and a power supply unit 500.
The control device 400 controls the overall operation of the thermal printer 100. For example, the control device 400 controls the conveyance of the sheet 1 by controlling the motor of the conveyance roller R. The control device 400 controls the printing mechanism to print data to be printed (hereinafter referred to as “print data”) on the sheet 1. The control device 400 determines the power to be applied to the non-printing use element based on the print data, and applies the determined power to the non-printing use element. Here, the power applied to the non-printing element corresponds to the first power. Further, the total power applied to the non-printing use elements corresponds to the first total power. The control device 400 determines the power to be applied to the print use element based on the print data, and applies the determined power to the print use element. Here, the power applied to the printing use element corresponds to the second power. In addition, the total power applied to the printing use element corresponds to the second total power.
The power supply unit 500 supplies power to the thermal printer 100. A broken line 23 represents a path through which data passes between the display unit 200 provided in the thermal printer 100 and the control device 400. A broken line 24 represents a path through which data passes between the control device 400 and the operation unit 300.

FIG. 4 is a schematic block diagram illustrating a functional configuration of the control device 400.
The control device 400 includes a CPU (Central Processing Unit), a memory, an auxiliary storage device, and the like connected by a bus, and executes a control program. By executing the control program, the control device 400 functions as a device including the storage unit 41, the acquisition unit 42, the transport control unit 43, and the print control unit 44. All or some of the functions of the control device 400 may be realized by using hardware such as an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA).
The control program may be recorded on a computer-readable recording medium. The computer-readable recording medium is, for example, a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built in the computer system. Further, the control program may be transmitted / received via a telecommunication line.

The storage unit 41 stores various information. The storage unit 41 includes an S power value information storage unit 411 and an S temperature / S stop power value information storage unit 412.
The S power value information storage unit 411 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device. The S power value information storage unit 411 stores an S power value information table. The S power value information table includes a record (hereinafter, referred to as “S power value information record”) representing information related to the S power value. The S power value is the total power applied to the print use elements when the number of print use elements is the largest among the print use elements for each print timing in the print pattern assumed at the time of printing (the number of print use elements) Represents the second total power). Hereinafter, the print use elements having the largest number of print use elements among the print use elements for each print timing in the print pattern assumed at the time of printing are collectively referred to as the maximum print use elements. The print pattern assumed at the time of printing is, for example, a print format.

FIG. 5 is a diagram illustrating a specific example of the S power value information table.
The S power value information table has a plurality of S power value information records 50. The S power value information record 50 has values of head temperature, ambient temperature, and S power value. The value of the head temperature represents the temperature of the thermal head 6. The value of the ambient temperature represents the temperature inside the thermal printer 100. The value of the S power value represents the total value of the power applied to the maximum printing use element under the head temperature and ambient temperature environment of the same S power value information record 50. In the S power value information table, S power values for each head temperature and ambient temperature at regular intervals are registered. The constant interval may be, for example, every 1 degree, every 5 degrees, or other. Note that only two values of the head temperature and the S power value may be registered in the S power value information table. In addition, only two values of the ambient temperature and the S power value may be registered in the power value information table. In the S power value information table, an approximate maximum value of printing density in a normal use form is obtained empirically or statistically, and the total power value in that case is calculated as paper feed speed, paper type, ink ribbon type, thermal The S power value calculated based on conditions such as head characteristics, head temperature, ambient temperature, and history compensation is registered. The S power value information table does not necessarily need to register all combinations of head temperature, ambient temperature, and S power value. For example, the S power value information table includes some combinations of data. It may be registered. Here, all combinations are combinations of the above-mentioned constant intervals. When some combinations of data are registered in the S power value information table, necessary data may be calculated by using a correction coefficient, an interpolation formula, or the like.

Returning to FIG. 4, the description of the control device 400 will be continued.
The S temperature / S stop power value information storage unit 412 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device. The S temperature / S stop power value information storage unit 412 stores an S temperature / S stop power value information table. The S temperature / S stop power value information table is composed of records (hereinafter referred to as “S temperature / S stop power value information record”) representing information on the S temperature and the S stop power value. The S temperature represents a temperature at which the thermal head 6 is supposed to reach when printing is continued by applying an S power value while the sheet 1 is being conveyed. The S stop power value represents a power value necessary for applying the same power to all the heating elements in a state where the sheet 1 is not conveyed and the head temperature rises to the S temperature.

FIG. 6 is a diagram illustrating a specific example of an S temperature / S stop power value information table.
The S temperature / S stop power value information table includes a plurality of S temperature / S stop power value information records 60. The S temperature / S stop power value information record 60 has each value of ambient temperature, S power value, S temperature, and S stop power value. The value of the ambient temperature represents the temperature inside the thermal printer 100. The value of the S power value represents the total value of the power applied to the maximum printing use element under the ambient temperature environment of the same S temperature / S stop power value information record 60. When the S temperature is the ambient temperature environment and the S power value of the same S temperature / S stop power value information record 60 and the S power value is applied while the sheet 1 is being conveyed and the printing is continued, the thermal head 6 represents the temperature assumed to be reached. When the S stop power value is the same S temperature / S stop power value information record 60 under the ambient temperature environment and the S power value, the same power is applied to all the heating elements without conveying the sheet 1, It represents the power value required for the temperature to rise to the S temperature. In the S temperature / S stop power value information table, the ambient temperature, S power value, S temperature, and S stop power value of all possible patterns are registered. A method for generating the S temperature / S stop power value information table will be described later. It should be noted that the S temperature / S stop power value information table does not necessarily require that all combinations of ambient temperature, S power value, S temperature, and S stop power value be registered. Some combinations of data may be registered in the power value information table. Here, all combinations are combinations of all the above patterns. When some combinations of data are registered in the S temperature / S stop power value information table, necessary data may be calculated by using a correction coefficient, an interpolation formula, or the like.

Returning to FIG. 4, the description of the control device 400 will be continued.
The acquisition unit 42 acquires various types of information. For example, the acquisition unit 42 acquires information on the ambient temperature from the ambient temperature measurement sensor. The acquisition unit 42 acquires head temperature information from the temperature sensor. The acquisition unit 42 acquires S power value information based on the acquired temperature information. The acquisition unit 42 acquires S temperature information based on the acquired S power value information. The acquisition unit 42 acquires S stop power value information based on the acquired S power value information.

The conveyance control unit 43 controls the conveyance of the sheet 1. Specifically, the conveyance control unit 43 conveys the sheet 1 by controlling the conveyance roller R and the platen roller PR.
The print control unit 44 controls the printing mechanism to print the print data on the sheet 1. At this time, the print control unit 44 applies power corresponding to the number of non-printing use elements among the plurality of heating elements of the platen roller PR to the non-printing use elements. In addition, the print control unit 44 applies higher power to the printing use element than the power applied to the non-printing use element.

Next, a method for creating the S temperature / S stop power value information table will be described.
First, as the S temperature and the S stop power value, values obtained by measuring the temperature and power value reached by the thermal head 6 after actually performing test printing under the conditions when the S power value is calculated may be used. Alternatively, values obtained by numerical simulation or empirical methods may be used.
However, it is desirable to obtain in advance a variety of conditions in the development stage before the manufacture and sale of the thermal printer 100. Then, the S temperature / S stop power value information table is created by registering the S temperature and S stop power value obtained as described above and other conditions (ambient temperature and S power value). The calculation of the S temperature and the S stop power value from the S power value may be performed by the S temperature / S stop power value information table created in advance by the above method. Note that when the S temperature / S stop power value information table is created in advance, the ambient temperature is the same as when the S power value is obtained, or it is handled as a temperature difference from the ambient temperature instead of an absolute temperature. Higher accuracy can be expected if conditions other than the above are met. The S stop power value is usually lower than the S power value. However, when the quality of the ink ribbon, thermal paper, or the like is deteriorated or discolored, or the element is deteriorated or damaged, the power value at which these values do not occur. The upper limit.
This is the end of the description of the method for creating the S temperature / S stop power value information table.

FIG. 7 is a schematic diagram of the inside of the thermal head 6.
As shown in FIG. 7, a plurality of heating elements R <b> 1 to R <b> 640 and a plurality of ICs 1 to 10 are provided inside the thermal head 6. A plurality of heating elements are connected to each IC. For example, the heating elements R1 to R64 are connected to the IC10. One terminal of each heating element is connected to the IC, and the other terminal is connected to the VH line segment. The power represented by the total value of the power applied to the heat generating elements R1 to R640 flows through the VH terminal. That is, power represented by the S power value and the S stop power value flows through the VH terminal. A control signal is input to the DI terminal. The control signal includes information indicating the power applied to each heating element. Control of the power supplied to each heating element is performed by an individual switch (not shown) connected to each heating element.

FIG. 8 is a flowchart showing the flow of processing of the thermal printer 100 in this embodiment. The process of FIG. 8 is executed when an instruction to start printing is input.
The acquisition unit 42 acquires temperature information from the ambient temperature measurement sensor and the temperature sensor (step S101). Specifically, the acquisition unit 42 acquires information on the ambient temperature from the ambient temperature measurement sensor, and acquires information on the head temperature from the temperature sensor. And the acquisition part 42 acquires S electric power value with reference to the S electric power value information table based on the acquired temperature information (step S102). Specifically, the acquisition unit 42 reads the S power value information table stored in the S power value information storage unit 411. Next, the acquisition unit 42 acquires the S power value information record 50 corresponding to the acquired head temperature and ambient temperature from among the S power value information records 50 of the read S power value information table. And the acquisition part 42 acquires S electric power value registered into the item of S electric power value of the acquired S electric power value information record 50. FIG.

  Next, the acquisition unit 42 acquires S temperature information and S stop power value information with reference to the S temperature / S stop power value information table based on the acquired S power value (steps S103 and S104). Specifically, the acquisition unit 42 reads the S temperature / S stop power value information table stored in the S temperature / S stop power value information storage unit 412. Next, the acquisition unit 42 includes the S temperature / S stop corresponding to the ambient temperature and the acquired S power value in the S temperature / S stop power value information record 60 of the read S temperature / S stop power value information table. The power value information record 60 is acquired. And the acquisition part 42 is the S temperature information registered in the S temperature item of the acquired S temperature / S stop power value information record 60 and the S stop power value registered in the S stop power value item. Get information.

The print controller 44 applies the S stop power indicated by the acquired S stop power value information to each heating element (step S105). Specifically, the print control unit 44 applies power obtained by dividing the S stop power by the number of all the heating elements to each heating element. Thereby, the electric power applied to each heat generating element becomes the same. The print controller 44 determines whether or not the head temperature has reached the vicinity of the S temperature (step S106). The determination as to whether or not the head temperature has reached the vicinity of the S temperature may be made based on information on the head temperature periodically acquired from the temperature sensor by the acquisition unit 42, or may be a predetermined time period set in advance. It may be made based on whether or not. If the head temperature has not reached the vicinity of the S temperature (step S106—NO), the print control unit 44 executes the processes after step S105.
On the other hand, if the head temperature has reached the vicinity of the S temperature (step S106—YES), the print control unit 44 notifies the conveyance control unit 43 that the head temperature has reached the vicinity of the S temperature.

  The conveyance control unit 43 conveys the sheet 1 by rotating the conveyance roller R and the platen roller PR (step S107). The conveyance control unit 43 determines whether or not the conveyance speed of the sheet 1 has reached the target speed (step S108). The determination as to whether or not the target speed has been reached may be made by actually measuring the linear velocity of the sheet 1 or by whether or not a predetermined time set in advance has passed. And it may be performed by measuring the rotation speed of the platen roller PR with an encoder or the like.

When the conveyance speed of the sheet 1 has not reached the target speed (NO in step S108), the conveyance control unit 43 waits until the conveyance speed reaches the target speed.
On the other hand, if the conveyance speed of the sheet 1 has reached the target speed (YES in step S108), the conveyance control unit 43 notifies the print control unit 44 that the conveyance speed has reached the target speed. When notified from the conveyance control unit 43, the print control unit 44 determines a printing use element based on the print data (step S109). Next, the printing control unit 44 determines the power to be applied to the printing use element (step S110). The power applied to the printing element is determined by dividing the S power value by the maximum number of printing elements. For example, when the S power value is 500 and the maximum number of print use elements is 50, the power applied to each print use element is 10.

  Next, the print control unit 44 determines the power to be applied to the non-printing use element (step S111). The power applied to the non-printing use elements is determined by dividing the difference between the S power indicated by the S power value and the second total power (first total power) by the number of non-printing use elements. For example, the number of heating elements of the thermal head 6 is 100, the S power value is 500, the number of printing elements used is 20, the number of non-printing elements is 80, and the power applied to the printing elements is 10. A method for determining the power applied to the non-printing element will be described as an example.

  First, the print control unit 44 calculates the second total power. In this case, the second total power is 200. Next, the print control unit 44 calculates the difference between the S power value and the second total power. In this case, the difference is 300. Then, the printing control unit 44 determines the power to be applied to each non-printing use element by dividing the calculated difference by the number of non-printing use elements. In this case, the power applied to each non-printing use element is 3.75.

The print control unit 44 applies the power determined in the processing of Step S110 and Step S111 to the printing use element and the non-printing use element, respectively (Step S112). Thereafter, the print control unit 44 controls the printing mechanism to print the print data on the sheet 1 (step S113). The print control unit 44 determines whether all printing has been completed (step S114). For example, when printing of the print data is completed, the print control unit 44 determines that all printing has been completed.
On the other hand, when printing of the print data is not completed, the print control unit 44 determines that all printing has not been completed.

When all printing is completed (step S114—YES), the thermal printer 100 ends the process.
On the other hand, if all printing has not been completed (step S114—NO), the conveyance control unit 43 conveys the sheet 1 by rotating the conveyance roller R and the platen roller PR (step S115). Thereafter, the processing after step S109 is executed.

FIG. 9 is a diagram illustrating a comparison result between the conventional method and the method according to the present embodiment.
In the description of FIG. 9, it is assumed that the total number of heating elements is 100, the S power value is 500, and the power value applied per printing use element is 10. The total number of heating elements is the number of all heating elements included in the thermal head 6.
In the example shown in FIG. 9, a comparison result between the conventional method and the method according to the present embodiment in the case where the number of printing use elements is 0, 10, 20, 30, 40, and 50 is shown. Hereinafter, this will be specifically described with reference to FIG.

  In the conventional method, when the number of elements used for printing is zero, the total power value of the power applied to all the heating elements is zero. In this case, since the heating element does not generate heat at all, the head temperature decreases. Further, in the conventional method, when the number of printing use elements is 20, the total power value of the power applied to all the heating elements is 200. In this case, the heating element generates heat and the head temperature rises. Further, in the conventional method, when the number of printing use elements is 50, the total power value of the power applied to all the heating elements is 500. In this case, the heating element generates heat and the head temperature rises. Thus, in the conventional method, the head temperature fluctuates according to the number of printing use elements. That is, the head temperature varies depending on the print data.

  On the other hand, in the method according to the present embodiment, when the number of printing use elements is zero, the total power value of the power applied to all the heating elements is 500. More specifically, the total power (second total power) applied to the number of printing use elements is 10 × 0 = 0, and the total power applied to non-printing use elements (first total power) is 500. Here, the power applied to each non-printing element is determined so that the total power value of the power applied to all the heat generating elements becomes the S power value (500 in the case of FIG. 8). When the number of printing use elements is 0, the number of non-printing use elements is 100. That is, since the second total power is 0, the first total power is 500. Then, 500 ÷ 100 = 5, and the power applied to each non-printing use element is 5. As a result, the heat generating elements generate heat with a power value of 500 in total.

  In the method according to the present embodiment, when the number of printing use elements is 20, the total power value of the power applied to all the heating elements is 500. More specifically, the total power (second total power) applied to the number of printing use elements is 10 × 20 = 200, and the total power applied to non-printing use elements (first total power) is 300. Here, the power applied to each non-printing element is determined so that the total power value of the power applied to all the heat generating elements becomes the S power value (500 in the case of FIG. 9). When the number of printing use elements is 20, the number of non-printing use elements is 80. That is, since the second total power is 10 × 20 = 200, the first total power is 300. Then, 300 ÷ 80 = 3.75, and the power applied to each non-printing use element is 3.75. As a result, the heat generating elements generate heat with a power value of 500 in total.

Further, in the method according to the present embodiment, when the number of printing use elements is 50, the total power value of the power applied to all the heating elements is 500. More specifically, the total power (second total power) applied to the number of printing use elements is 10 × 50 = 500, and the total power applied to non-printing use elements (first total power) is 0. Here, the power applied to each non-printing element is determined so that the total power value of the power applied to all the heat generating elements becomes the S power value (500 in the case of FIG. 9). When the number of printing use elements is 50, the number of non-printing use elements is zero. That is, since the second total power is 10 × 50 = 500, the first total power is zero. Then, 0 ÷ 50 = 0, and the power applied to each non-printing use element is zero. As a result, the heat generating elements generate heat with a power value of 500 in total.
As described above, in the method according to the present embodiment, heat is generated so that the total power value of all the heating elements becomes the S power value even when the number of non-printing elements is other than the above. Therefore, the head temperature can be maintained at a constant value (S temperature) regardless of the print data.

According to the thermal printer 100 configured as described above, it is possible to suppress a decrease in print quality. Hereinafter, this effect will be described in detail.
The thermal printer 100 applies power corresponding to the number of non-printing heating elements that are not used for printing among the plurality of heating elements included in the thermal head 6 to the non-printing heating elements. Thereby, electric power is also applied to the heating elements that are not used for printing. Further, power corresponding to the number of non-printing heat generating elements is applied to the non-printing heat generating elements. That is, equal power is applied to each non-printing heat generating element. Therefore, the thermal printer 100 can increase the temperature of the entire thermal head 6 before printing. Therefore, it is possible to suppress a decrease in print quality.

Further, the thermal printer 100 applies power higher than power applied to each non-printing heat generating element to each printing heat generating element. As a result, the thermal printer 100 can print the print data using only the print heating elements even when power is applied to all the heating elements.
Further, the thermal printer 100 determines the power to be applied to the non-printing element based on the difference between the S power value and the total power value of the power applied to the printing element and the number of non-printing heating elements. For example, the thermal printer 100 determines the power applied to each non-printing use element by dividing the difference by the number of non-printing heating elements. Therefore, the total value of the power applied to all the heat generating elements is constant regardless of the number of non-printing heat generating elements. Therefore, the head temperature can be kept constant.

Hereinafter, modified examples of the thermal printer 100 will be described.
In the present embodiment, the label roll paper 1 has been described as an example, but the thermal printer 100 can also be applied to cut paper.
In the present embodiment, the configuration in which power is applied to all the heat generating elements included in the thermal head 6 has been described. However, the application of power is not necessarily limited to this. For example, the thermal printer 100 applies power to all the heat generating elements of the thermal head 6 except for the heat generating elements that are not used for printing among all the heat generating elements of the thermal head 6. May be configured.
The application of power in the above description may be performed by any method of DC application, pulse application, and AC application. However, pulse application is usually used, and means for adjusting the power value by adjusting the pulse width with a constant voltage value is used. This is because the adjustment of the pulse width is easier than the adjustment of the voltage value.

As for the S power value, when the maximum number of printing elements simultaneously used for printing is large and occupies a considerable proportion (for example, 80%) of the total number of heating elements included in the thermal head 6, the S power value is large. It becomes too much. Since such a case is assumed, a threshold value of the S power value may be set. For example, consider a case where the S power value is 1000 under the preconditions used in the description of FIG. If there is a printing pattern in which all the heating elements print simultaneously, for example, a horizontal line pattern with a full width in the direction along the thermal head 6, the S power value is 1000.
In such a case, if there is print data with 0 print-use elements, it is necessary to add 10 power values to each non-print-use element. Then, since it becomes equal to the electric power value 10 applied per printing use element, the case where it results in printing despite a non-printing use element is assumed. That is, as the S power value approaches the maximum value 1000 that can be assumed, the difference between the power values of the printing use element and the non-printing use element becomes small, and the margin becomes small. Therefore, in order to prevent such a case, the S power value is decreased by providing a threshold value of the S power value. Thereby, by allowing a short-term temperature rise of the thermal head 6 in a local print pattern that exceeds the S power value, it is possible to increase the margin and minimize the adverse effect on the print quality. is there.

  Further, the thermal printer 100 may be configured to change the S power value during printing when the ambient temperature varies greatly during printing. For example, when the room temperature largely fluctuates during long-term continuous printing, the ambient temperature is affected and fluctuates. In that case, the print temperature may be adversely affected by the head temperature. In such a case, the thermal printer 100 temporarily changes the S power value based on the ambient temperature so that the head temperature is kept constant. For example, the acquisition unit 42 acquires S power value information based on the ambient temperature from the S power value information table. Then, the print control unit 44 changes the S power value from the acquired information to the newly acquired S power.

  In the process of step S106 in FIG. 8, it is desirable to apply only for a period in which there is no excess or deficiency until the head temperature reaches the vicinity of the S temperature, which is appropriate in terms of saving time until starting printing and power consumption. However, after the power is supplied to the thermal printer 100, the thermal printer 100 may always apply power regardless of the start of printing. If the influence on the print quality is within an allowable range, the thermal printer 100 is close to the S temperature. It is also possible to apply power for a period shorter than the period until it reaches. For example, the thermal printer 100 assumes a two-stage state in which idling and immediate printing are possible, and switches the power value in accordance with this and applies it to the heating element, and generates heat lower than the S stop power value during idling. In the state where it is applied to the element and immediate printing is possible, adjustments such as applying the S stop power value to the heating element may be performed to achieve both reduction of power consumption and time to start printing. Absent.

Further, the print head 6-1 may be configured to include a head temperature heating unit or cooling unit, or an ambient temperature heating unit or cooling unit.
Further, the thermal printer 100 is configured such that the length of the pulse and the voltage value are set so that the temperature of the heating element does not excessively increase when printing by the same printing element continues, or when the heating element adjacent to the printing element is simultaneously printed. So-called history compensation may be performed.

  The thermal printer 100 may be configured to apply power corrected based on the head temperature to the heating element. For example, the thermal printer 100 applies the power applied to the non-printing use element, corrected based on the head temperature, to the non-printing use element. Further, the thermal printer 100 applies the power applied to the printing use element, corrected based on the head temperature, to the printing use element. The thermal printer 100 performs a process of applying the power corrected based on the head temperature to the heating element during a period during which printing is performed or a period in which sheet conveyance is stopped without performing printing. Hereinafter, the process of applying the power corrected based on the head temperature to the heating element during the printing period will be specifically described.

When the head temperature is excessively high, for example, when the head temperature is excessively high due to continuous printing, the temperature of the heating element also increases. Therefore, when the head temperature is excessively high, the print control unit 44 corrects the power applied to each printing use element determined in the process of step S110 in FIG. For example, the print control unit 44 determines, as the power applied to each print use element, a power lower than the power applied to each print use element determined in the process of step S110 of FIG. Thereafter, the print control unit 44 determines the power to be applied to the non-printing use element. As described above, the power applied to the non-printing use element is obtained by dividing the difference between the S power indicated by the S power value and the second total power (first total power) by the number of non-printing use elements. It is determined. In this way, the print control unit 44 applies the power corrected based on the head temperature to the heating element. Note that, when the head temperature is excessively high, the power applied to each printing element may be set in advance using a table or the like.
This is the end of the description of the process of applying the power corrected based on the head temperature to the heating element during the printing period.

The process of applying the power corrected based on the head temperature to the heating element during the period when the sheet conveyance is stopped without printing is performed as follows.
When the head temperature is excessively high, for example, when the head temperature is excessively high due to continuous printing, the temperature of the heating element also increases. Therefore, when the head temperature is excessively high, the print control unit 44 corrects the S stop power applied to all the heating elements in the process of step S105 in FIG. For example, the print control unit 44 determines a power lower than the S stop power applied to all the heat generating elements in the process of step S105 of FIG. 8 as the S stop power applied to all the heat generating elements. In this way, the print control unit 44 applies the power corrected based on the head temperature to the heating element. When the head temperature is excessively high, the S stop power applied to all the heat generating elements may be set in advance using a table or the like.
This is the end of the description of the process of applying the power corrected based on the head temperature to the heating element during the period in which the sheet conveyance is stopped without printing.

The thermal printer 100 may be configured to apply power corrected based on the ambient temperature to the heating element. Since this process is the same as the process of applying the power corrected based on the head temperature to the heating element, a description thereof will be omitted.
The thermal printer 100 may be configured to include a setting unit that sets a temperature (for example, an ambient temperature) input by a user. When configured in this way, the thermal printer 100 applies power corrected by the temperature set by the setting unit to the heating element. In the thermal printer 100, the process of applying the power corrected based on the temperature set by the setting unit to the heating element is performed during a period during which printing is performed or a period in which sheet conveyance is stopped without performing printing. Do. The actual process is the same as the process of applying the power corrected based on the head temperature or the ambient temperature to the heating element, and the description thereof will be omitted.

  According to at least one embodiment described above, a plurality of heating elements that generate heat upon application of power, and a non-printing use element in a region composed of a plurality of continuous pixels in one line of print data among the plurality of heating elements The first power is applied to the print element, the second power higher than the first power is applied to the printing use element among the plurality of heating elements, and the total power indicating the total power applied to the plurality of heating elements is constant. By having the print control unit 44 that determines the first power and the second power and the printing unit that performs printing using a plurality of heating elements, it is possible to suppress a decrease in print quality. .

  Some functions of the thermal printer 100 in the above-described embodiment may be realized by a computer. In that case, a program for realizing this function is recorded on a computer-readable recording medium. And you may implement | achieve by making a computer system read the program recorded on the recording medium which recorded the program mentioned above, and executing it. Here, the “computer system” includes hardware such as an operating system and peripheral devices. The “computer-readable recording medium” refers to a portable medium, a storage device, and the like. The portable medium is a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or the like. The storage device is a hard disk or the like built in the computer system. Further, the “computer-readable recording medium” is a program that dynamically holds a program for a short time like a communication line in the case of transmitting a program via a communication line. The communication line is a network such as the Internet or a telephone line. Further, the “computer-readable recording medium” may be a volatile memory inside a computer system serving as a server or a client. Volatile memory holds a program for a certain period of time. The program may be for realizing a part of the functions described above. Further, the program may be a program that can realize the above-described functions in combination with a program already recorded in the computer system.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Sheet | seat, 2 ... Roll part, 3 ... Ink ribbon, 4 ... Supply axis | shaft, 5 ... Winding axis | shaft, 6 ... Thermal head, 6-1 ... Print head, 7 ... Conveyance path, 100 ... Thermal printer, 200 ... Display Unit, 300 ... operation unit, 400 ... control device, 41 ... storage unit, 411 ... S power value information storage unit, 412 ... S temperature / S stop power value information storage unit, 42 ... acquisition unit, 43 ... transport control unit, 44 ... Print control unit, 500 ... Power supply unit

Claims (6)

A plurality of heating elements that generate heat upon application of power;
A first electric power is applied to a heating element that is not used for printing a region composed of a plurality of continuous pixels in one line of print data among the plurality of heating elements, and the first heating power is used for printing among the plurality of heating elements. A second power higher than the first power is applied to the heating element, and the first power and the second power are set such that a total power representing a total of power applied to the plurality of heating elements is constant. A print control unit for determining power;
A printing unit that performs printing using the plurality of heating elements;
Thermal printer equipped with.   2. The thermal printer according to claim 1, wherein the print control unit determines the second power so as to have the same power for each of the heating elements used for the printing. The second total power representing the total of the second power is predetermined,
The thermal printer according to claim 1, wherein the print control unit determines the first power based on the second total power.   The thermal printer according to claim 3, wherein the total power is the same as the second total power when the number of heat generating elements used for the printing is the largest in the print data. It further includes a sensor that measures the head temperature of the thermal head or the ambient temperature, or a setting unit that sets the temperature.
The thermal printer according to claim 3 or 4, wherein the second total power is determined by a measured or set temperature. A first power is applied to a heating element that is not used for printing in a region composed of a plurality of continuous pixels in one line of print data among a plurality of heating elements that generate heat upon application of power, and among the plurality of heating elements Applying the second power higher than the first power to the heating element used for printing, the first power and the total power representing the sum of the power applied to the plurality of heating elements are constant. A printing control step for determining the second power;
A printing step for performing printing using the plurality of heating elements;
A computer program for causing a computer to execute.

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