Printing device, printing control method, storage medium, and computer program product

Abstract

A printing apparatus, a printing control method, and a storage medium are provided. The control device (40) of the printing apparatus (10) sets a set of adhesion countermeasure target dot groups that includes at least the second dot group when the following conditions are met: the proportion of printing areas with a first concentration or higher in the first dot group is a first threshold or higher; and the comparison result between the printing areas with a first concentration or higher in the first dot group and the printing areas with a second concentration lower than the first concentration in the subsequent second dot group is a second threshold or higher. In addition to the first power-on control period (TA) for printing on the printed medium (20), the control device sets a second power-on control period (TB) for adjusting the temperature change of the thermal head (30) without printing on the printed medium, and generates countermeasure data for energizing at least a portion of a plurality of heating elements during the second power-on control period of each dot group in the set of adhesion countermeasure target dot groups.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefits from Japanese Patent Application No. 2022-150829, filed on September 22, 2022, the entire contents of the description, claims and drawings of Japanese Patent Application No. 2022-150829 of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to printing apparatus, printing control methods, and storage media. Background Technology

[0004] In printing apparatuses (thermal printers) that print onto a substrate by applying heat to a thermal developer or ink ribbon from a thermal printhead, thermal printhead adhesion (sticking) sometimes occurs during printing. For example, in thermal printers that develop the developer contained in the substrate through heating, the thermal printhead adheres to the substrate, resulting in sticking. In thermal transfer printers that transfer ink coated on an ink ribbon to the substrate through heating, the thermal printhead adheres to the ink ribbon, also resulting in sticking. Sticking is a cause of degraded print quality.

[0005] In thermal printing, the thermal printhead experiences temperature changes depending on the printed pattern. Furthermore, the thermal printhead is prone to sticking when its temperature changes rapidly from high to low.

[0006] Japanese Patent Application Publication No. 2013-52539 describes a thermal printer that prevents sticking by using chopper control. Chopper control is a technique that frequently switches between energizing and de-energizing the thermal printhead. By performing chopper control, it is possible to prevent rapid temperature changes in the thermal printhead. Summary of the Invention

[0007] As described in Japanese Patent Application Publication No. 2013-52539, the key point of existing adhesion countermeasures is to suppress temperature changes (especially temperature drops) of the thermal printhead by preventing a decrease in the frequency of energizing the thermal printhead. However, the countermeasures described in Japanese Patent Application Publication No. 2013-52539 may not be appropriate depending on the printing performance. For example, sometimes energizing for adhesion countermeasures is performed even when the risk of adhesion is low. Energizing the thermal printhead for adhesion countermeasures when the risk of adhesion is low wastes energy. Furthermore, it is required that even when energizing the thermal printhead for adhesion countermeasures, it should not affect the printing quality. In other words, there is a challenge in recognizing situations with a high risk of adhesion and implementing adhesion countermeasures that are neither excessive nor insufficient.

[0008] The purpose of this disclosure is to provide a printing apparatus, printing control method, and storage medium that can effectively suppress the adhesion of thermal heads.

[0009] A printing apparatus according to a technical solution of this disclosure is characterized by comprising: a thermal head having a plurality of heating elements, which prints onto a printable medium in each dot group, wherein the dot group is composed of a plurality of dots corresponding to the plurality of heating elements; and a control device, wherein the control device is set to [a certain condition] when the following conditions are met: in a first dot group, the proportion of printing areas with a first concentration or higher is a first threshold or higher; and the comparison result between the printing areas with a first concentration or higher in the first dot group and the printing areas with a second concentration or higher in a second dot group is a second threshold or higher. The set of adhesion countermeasure target point groups includes the aforementioned second point group, wherein the second point group is located later than the aforementioned first point group, and the second concentration is lower than the aforementioned first concentration. In addition to the first power-on control period for printing on the aforementioned printable medium, the aforementioned control device sets a second power-on control period for adjusting the temperature change of the aforementioned thermal head instead of printing on the aforementioned printable medium, and generates countermeasure data. This countermeasure data is used to power on at least a portion of the aforementioned plurality of heating elements during the aforementioned second power-on control period of each point group in the aforementioned set of adhesion countermeasure target point groups.

[0010] A printing control method of the present disclosure, based on printing data for printing onto a printing medium by a thermal head having multiple heating elements in each dot group, sets up a set of adhesion countermeasure target dot groups that includes at least the second dot group, wherein the proportion of printing areas with a first concentration or higher in the first dot group is a first threshold or higher; and the comparison result between the printing areas with the first concentration or higher in the first dot group and the printing areas with a second concentration or higher in the second dot group is a second threshold or higher, wherein the dot group consists of multiple dots corresponding to the multiple heating elements, the second dot group is located later than the first dot group, and the second concentration is lower than the first concentration. Outside of a first power-on control period for printing onto the printing medium, a second power-on control period is set for adjusting the temperature change of the thermal head instead of printing onto the printing medium, and countermeasure data is generated. This countermeasure data is used to power on at least a portion of the multiple heating elements during the second power-on control period of each dot group in the adhesion countermeasure target dot group set.

[0011] A computer-readable, non-transitory storage medium containing a program is provided in relation to a technical solution of this disclosure. The program instructs a computer in a printing apparatus to perform the following processing: based on printing data for printing onto a printable medium by a thermal head having multiple heating elements in each dot group, and provided that the following conditions are met: in the first dot group, the proportion of printing areas with a first concentration or higher is at least a first threshold; and the comparison result between the printing areas with the first concentration or higher in the first dot group and the printing areas exceeding a second concentration in the second dot group is at least a second threshold, a setting is established that includes at least the aforementioned first... A set of two-point adhesion countermeasure target point groups, wherein the point groups consist of multiple points corresponding to the multiple heating elements, the second point group is located later than the first point group, and the second concentration is lower than the first concentration. In addition to the first power-on control period for printing on the printed medium, a second power-on control period is set for adjusting the temperature change of the thermal head instead of printing on the printed medium. Countermeasure data is generated, which is used to power on at least a portion of the multiple heating elements during the second power-on control period of each point group in the set of adhesion countermeasure target point groups.

[0012] Invention Effects

[0013] Based on the above technical solutions, the implementation of adhesion countermeasures can be minimized, effectively suppressing the occurrence of adhesions. Attached Figure Description

[0014] Figure 1 This is a front view of the printing apparatus.

[0015] Figure 2 This is a front view of the boxed items stored in the box storage section.

[0016] Figure 3 It is a block diagram representing the hardware structure of a printing apparatus.

[0017] Figure 4 This diagram illustrates an example of a one-point cycle of power-on control for a thermal head.

[0018] Figure 5 It is a block diagram representing the functional structure of a printing apparatus.

[0019] Figure 6 This diagram illustrates the method for determining the cluster of points where adhesion occurs and the method for setting patterns for countermeasure data.

[0020] Figure 7 This is a flowchart of the adhesion countermeasures process.

[0021] Figure 8 This is a flowchart for determining and processing the cluster of points where adhesion is predicted.

[0022] Figure 9 This diagram illustrates a method for determining the cluster of adhesion points in another type of printing device and a method for setting pattern data for countermeasures. Detailed Implementation

[0023] The specific embodiments described below will be described in detail with reference to the accompanying drawings. Figure 1 This is a front view of the printing apparatus 10 according to this embodiment. The printing apparatus 10 includes a thermal head 30 (see reference 30). Figure 2 A thermal printer, which serves as the printing unit, prints, for example, on a strip 20, which is a long strip of printable medium, in a single-pass manner.

[0024] The tape 20 is a heat-sensitive tape that develops color by heating. For example, the tape 20 is a structure consisting of a substrate having an adhesive layer, a color-developing layer containing a color developer, and a peelable release paper adhered to the adhesive layer of the substrate.

[0025] The printing device 10 has a device housing 11, an input section 12 on the front side of the upper surface of the device housing 11, and a display device 13 and an opening / closing cover 14 on the inner side of the upper surface of the device housing 11.

[0026] The input unit 12 is equipped with multiple input keys, etc., and by operating the input unit 12, one can input the printing content such as characters or graphics to be printed, input various actions related to the execution of printing, and select other functions or settings. In addition, the input of the printing content of the printing device 10 can also be performed using a storage medium such as a memory card or through communication with an external device.

[0027] The display device 13 is equipped with a display mechanism such as a liquid crystal display panel, and can display characters or graphics corresponding to input to the input unit 12, display selection menus for various settings, display messages related to various processes, and display the progress of printing processes. In addition, the display device 13 can be configured to accept input types (such as touch panel input), so that the display device 13 can function as an input unit 12.

[0028] The cover 14 is closable relative to the housing 11. Inside the housing 11, there is a box storage section 15 covered by the cover 14 in the closed state (see reference). Figure 2 The internal structure of the box storage section 15 will be described later. The opening and closing cover 14 can be locked when closed, and the lock can be released by pushing the release button 16 to open the opening and closing action of the cover 14.

[0029] On the side of the device housing 11, an outlet 17 leading to the box storage section 15 is formed (see reference). Figure 2The tape 20, after being printed inside the printing apparatus 10, is discharged to the outside of the printing apparatus 10 via the discharge port 17.

[0030] Figure 2 This indicates that the tape cassette 21 is stored in the cassette storage section 15 of the printing apparatus 10. The tape cassette 21 has a tape core 23 inside the box-shaped casing 22, and the rolled tape 20 is supported by the tape core 23.

[0031] A thermal head 30 is provided inside the box storage section 15. The thermal head 30 has multiple heating elements 30a (see reference) that are heated and controlled during printing on the tape 20. Figure 3 In the thermistor head 30, a thermistor 31 is embedded as a temperature measuring part for measuring temperature (see reference). Figure 3 In addition, an impression roller 32 and a core locking shaft 33 are provided inside the box storage section 15.

[0032] Inside the box storage section 15, there are also multiple box receiving parts 34 for supporting the tape box 21 at a predetermined position and a tape width detection switch 35 for detecting the width of the tape 20 contained in the tape box 21 (see reference). Figure 3 The width detection switch 35 is a detection unit that detects the width of the tape 20 based on the shape of the tape box 21.

[0033] Near the outlet 17 of the device housing 11, there are a full cutter 36 and a half cutter 37 for cutting the strip 20 along its width direction. The full cutter 36 cuts the entire thickness of the strip 20, including the release liner. The half cutter 37 cuts the strip 20 while retaining the release liner.

[0034] With the tape cassette 21 housed in the cassette storage section 15, the tape core 23 of the tape cassette 21 engages with the tape core engaging shaft 33, and the tape 20 pulled out from the tape core 23 passes between the thermal head 30 and the impression roller 32. If the opening and closing cover 14 is closed, the thermal head 30 approaches the impression roller 32, and the tape 20 is sandwiched between the thermal head 30 and the impression roller 32.

[0035] If an instruction to perform printing is input into the printing apparatus 10, the impression roller 32 is driven to rotate, and the belt 20 is fed out and conveyed from the belt core 23. Then, as the belt 20 passes between the thermal head 30 and the impression roller 32, the developing layer of the belt 20 develops color and is printed at the portion heated by the thermal head 30.

[0036] The printed tape 20 passing between the thermal head 30 and the impression roller 32 is cut by the full cutter 36 or the half cutter 37 (full cut or half cut) and discharged from the discharge port 17 to the outside of the box storage section 15.

[0037] Figure 3This is a block diagram showing the hardware structure of the printing apparatus 10. The block diagram includes the aforementioned input unit 12, display device 13, thermal head 30, thermistor 31, impression roller 32, width detection switch 35, full cutter 36, and half cutter 37. The printing apparatus 10 also includes a control device 40, ROM (Read Only Memory) 41, RAM (Random Access Memory) 42, display device drive circuit 43, head drive circuit 44, conveyor motor drive circuit 45, stepper motor 46, cutter motor drive circuit 47, cutter motor 48, and temperature sensor 49.

[0038] The control device 40 includes a processor 40a, such as a CPU (Central Processing Unit). The control device 40 controls the operation of various parts of the printing apparatus 10 by reading a program stored in ROM 41, loading it into RAM 42, and executing it. The series of controls and processes related to adhesion countermeasures, described later, are also performed based on the program stored in ROM 41. Furthermore, at least the control device 40, ROM 41, and RAM 42 constitute the computer of the printing apparatus 10.

[0039] ROM 41 stores the printing program for printing on tape 20, and various data required for executing the printing program (e.g., font, power meter, etc.). RAM 42 includes a printing data storage unit 42a for storing printing data (see reference). Figure 5 The above printing data represents the pattern (image) of the printed content.

[0040] The display device driving circuit 43 includes a display driver that drives the display device 13. Printing content, printing progress, etc., based on printing data stored in RAM 42, are displayed on the display device 13 under the control of the display device driving circuit 43.

[0041] The head drive circuit 44 is a head drive unit that drives the thermal head 30 based on a gating pulse signal, printing data, and countermeasure data supplied from the control device 40 as control signals. The head drive circuit 44 controls whether to energize or de-energize the multiple heating elements 30a.

[0042] The thermal head 30 has a scanning direction (refer to) Figure 6 The printhead has multiple heating elements 30a arranged on it. The main scanning direction is also the width direction of the strip 20. During the power-on control of the gating pulse signal supplied from the control device 40, the head drive circuit 44 selectively applies voltage to the multiple heating elements 30a of the thermal head 30 according to the printing data or countermeasure data, so that the heating elements 30a at the location specified by the printing data or countermeasure data are heated.

[0043] Belt 20 aligns the length direction with the sub-scanning direction perpendicular to the main scan direction (see reference). Figure 6 The tape 20 is conveyed to the position of the thermal head 30 by moving in the sub-scanning direction. Then, while conveying the tape 20 in the sub-scanning direction, the heating of each heating element 30a of the thermal head 30 is controlled, so that the thermal head 30 prints on the tape 20 according to each dot group consisting of multiple dots corresponding to multiple heating elements 30a. That is, by changing the relative position of the thermal head 30 and the tape 20 in the sub-scanning direction and controlling the heating of each heating element 30a of the thermal head 30, multiple dot groups on the tape 20 are printed sequentially.

[0044] The conveyor motor drive circuit 45 drives the stepper motor 46, which in turn rotates the impression roller 32. The impression roller 32, powered by the stepper motor 46, rotates and conveys the belt 20 along its length (sub-scanning direction). By counting the number of pulses input to the stepper motor 46, information related to the conveying quantity of the belt 20 can be obtained.

[0045] The cutter motor drive circuit 47 drives the cutter motor 48. The full cutter 36 and the half cutter 37 are operated by the power of the cutter motor 48, which will make full or half cuts on the belt 20.

[0046] Temperature sensor 49 is an ambient temperature measuring unit that measures the temperature around the printing apparatus 10 as the ambient temperature.

[0047] When printing is performed by the printing apparatus 10, if a rapid temperature change (temperature drop) occurs in the thermal head 30 from a high temperature state to a low temperature state, the thermal head 30 may adhere to the tape 20, i.e., sticking. This rapid temperature drop in the thermal head 30 is prone to occur when printing content that suddenly switches from a high-printing-rate (numerous heating elements 30a) dot group to a low-printing-rate (few heating elements 30a) dot group. In other words, sticking is prone to occur when printing boundary portions where the printing rate drops sharply between adjacent or closely spaced dot groups in the sub-scanning direction.

[0048] Furthermore, the printing apparatus 10 performs multi-grayscale printing at different densities of three or more gray levels for each printing area (dot) corresponding to each heating element 30a of the thermal head 30. The higher the printing density in each printing area, the greater the current supplied to the heating element 30a, and the easier it is for the temperature of the thermal head 30 to rise. Therefore, in addition to the printing rate of the dot group, the printing density of each dot is also related to the occurrence of adhesion. Specifically, adhesion is more likely to occur when printing content suddenly switches from a dot group with high printing density to a dot group with low printing density.

[0049] In the printing apparatus 10, adhesion is suppressed by controlling the energization of the heating element 30a of the thermal head 30. Specifically, within a 1-point cycle corresponding to each point group, a first energization control period for printing on the tape 20 and a second energization control period for adjusting the temperature change of the thermal head 30 without printing on the tape 20 are set, and the energization and de-energization of the heating element 30a during the first and second energization control periods are controlled.

[0050] Figure 4 This diagram illustrates an example of the energizing control of a single-point period T for each heating element 30a of the thermal head 30, corresponding to multi-grayscale printing. The first energizing control period TA includes multiple energizing times P1-P7. In each energizing time P1-P7, ON means energized, and OFF means not energized. The number of energizing times corresponds to the printed grayscale; energizing for all energizing times P1-P7 results in the highest grayscale density. As the number of energizing times decreases, the printed density becomes lighter (grayscale decreases), and energizing only with the minimum number of energizing times results in the lightest density printing. Furthermore, when no energizing is applied for all energizing times P1-P7, there are unprinted areas (white dots). That is, Figure 4 The power-on control illustrates the case of printing at the maximum gray level (highest density) in the thermal head 30, which is capable of displaying eight levels of grayscale from no printing to the maximum grayscale.

[0051] The second power-on control period TB is a period used to adjust the temperature change of the thermal head 30 instead of printing on the tape 20, and is set to be a period separate from the first power-on control period TA. When TA is not energized during the first power-on control period or when the energizing time is short (few energizing cycles), by energizing (ON) the heating element 30a during the energizing time P8 in the second power-on control period TB, the temperature drop of the heating element 30a can be suppressed. Thus, the printing apparatus 10 suppresses adhesion by applying voltage to the thermal head 30 during the second power-on control period TB, as detailed below.

[0052] Figure 5 This is a block diagram illustrating the functional structure of the printing apparatus 10 related to inhibiting adhesion. Figure 5 The diagram primarily illustrates the functional structure of the control device 40 included in the printing apparatus 10. The control device 40 includes a determination unit 50, a data generation unit 60, and a head control unit 70. Furthermore, the control device 40 does not necessarily include components similar to those in the previous diagram. Figure 5 The electronic components or circuits corresponding to the functional blocks shown may also have multiple functions or be established as one functional block through the cooperation of multiple electronic components or circuits.

[0053] The determination unit 50, based on printing data including multiple dot group data corresponding to multiple dot groups printed by the thermal head 30, determines whether a second dot group (a dot period after the first dot group, a predetermined number of times relative to the first dot group) is a dot group with a high probability of adhesion (hereinafter referred to as an adhesion-predicted dot group). Dot groups with a high probability of adhesion are those where the temperature of the thermal head 30 is likely to drop sharply. The printing data used by the determination unit 50 is read from the printing data storage unit 42a of the RAM 42. In this embodiment, the case where the first and second dot groups are consecutive dot groups will be described as an example, where the first dot group is denoted as the (n-1)th dot group, and the second dot group is denoted as the nth dot group (n is an integer greater than or equal to 2).

[0054] The determination unit 50 includes a prior point group determination unit 51 and a comparison unit 52. The prior point group determination unit 51 determines whether the point group data of the (n-1)th point group preceding the nth point group meets the prescribed conditions. The comparison unit 52 compares the point group data of the (n-1)th point group with the point group data of the nth point group and determines whether the relationship between the two point groups meets the prescribed conditions. Furthermore, if both the prior point group determination unit 51 and the comparison unit 52 determine that the prescribed conditions are met, the determination unit 50 determines that the nth point group is a point group with a presumed adhesion occurrence.

[0055] More specifically, the dot group determination unit 51 determines whether the proportion of the printed area with a concentration of 1 or higher in the (n-1)th dot group is greater than or equal to a first threshold. For example, it is preferable to print multiple gray levels (e.g., by...) Figure 4 The highest gray level among the eight gray levels controlled by the power-on mechanism is set as the first concentration. Furthermore, it is preferable to set two-thirds of the entire printing area relative to the width direction (main scanning direction) of the band 20 as the first threshold. That is, when the printing area with the highest gray level (the number of points printed at the highest gray level) in the printing area (the total number of points constituting a dot group) in the width direction of the band 20 is two-thirds or more, the dot group determination unit 51 determines that the dot group data of the (n-1)th dot group meets the first condition for adhesion occurrence. Regarding the printing area in the width direction of the band 20, in addition to the dot group data, information about the band width detected by the band width detection switch 35 can also be referenced.

[0056] The first condition determined by the prior dot group determination unit 51 is related to the degree to which the temperature of the thermal head 30 increases when printing the (n-1)th dot group. If the first condition is met, the printing rate at high gray levels in the (n-1)th dot group is high, so it is inferred that the temperature of the thermal head 30 increases.

[0057] The comparison unit 52 determines whether the ratio of the printed area of ​​the (n-1)th point group with a first concentration or higher to the printed area of ​​the nth point group with a second concentration lower than the first concentration is greater than or equal to a second threshold. For example, it is preferable to set the printed area of ​​the second concentration as a non-printed area (white dot). Furthermore, it is preferable to set the second threshold to 1.5 times. That is, if the ratio of the printed area of ​​the (n-1)th point group with the maximum gray level (the number of dots printed at the maximum gray level) to the printed area of ​​the nth point group other than the non-printed area (the number of dots printed at a certain concentration from the minimum gray level to the maximum gray level) is greater than or equal to 1.5 times, the comparison unit 52 determines that the relationship between the dot group data of the (n-1)th point group and the dot group data of the nth point group meets the second condition for adhesion to occur.

[0058] The second condition determined by the comparison unit 52 is related to the degree of temperature drop of the thermal head 30 when printing is transferred from the (n-1)th point group to the nth point group. If the second condition is met, the printing level obtained by multiplying the printing rate by the gray level in the (n-1)th point group is much greater than the printing level obtained by multiplying the printing rate by the gray level in the nth point group, which is presumably because the temperature drop of the thermal head 30 becomes significant.

[0059] If both conditions 1 and 2 are met, when printing from the (n-1)th dot group to the nth dot group, the temperature of the thermal head 30 drops sharply from a high state, suggesting that adhesion is likely to occur. Therefore, if the prior dot group determination unit 51 and the comparison unit 52 determine that conditions 1 and 2 are met, the determination unit 50 determines that the nth dot group is a dot group where adhesion is predicted to occur.

[0060] In this way, by determining the two dot group data corresponding to two adjacent printed dot groups respectively, it is possible to anticipate the rapid temperature changes that may occur between the two adjacent printed dot groups and determine the predicted dot groups where adhesion may occur. In particular, by determining not only the printing rate of each dot group but also the grayscale information of the printed area, it is possible to predict the temperature changes of the thermal head 30 with high accuracy, thereby achieving the effect of minimizing the required adhesion countermeasures.

[0061] In this embodiment, the printing area with the first concentration is set as the printing area with the highest gray level, and the printing area with the second concentration is set as the non-printing area. The determination is based on the difference in gray levels between the (n-1)th point group and the nth point group where a sharp temperature drop is most likely to occur. However, the first or second concentration can also be set to the concentration of an intermediate gray level among multiple gray levels. That is, it is sufficient to satisfy at least the relationship that the second concentration is a lower printing concentration (gray level) than the first concentration.

[0062] Furthermore, in the comparison between the (n-1)th point group and the nth point group determined by the comparison unit 52, the judgment may not be based on the absolute value of the gray level (the specified printing density), but rather on the comparison of gray level differences. That is, the second condition for adhesion to occur may be set based on the number of points with a specified or greater gray level difference between the (n-1)th point group and the nth point group. As an example, in the printing of 8 gray levels from 0 (no printing) to 7 (maximum gray level), if the nth point group has p (p is any integer) or more points with a lower gray level of m or greater than the (n-1)th point group (m is an integer less than 7), the comparison unit 52 determines that the second condition for adhesion to occur is met.

[0063] Furthermore, the first threshold (2 / 3 in this embodiment) and the second threshold (1.5 times in this embodiment) in the determination unit 50 are examples of the same value, but they can also be different values. For example, these values ​​can also be changed based on the ambient temperature measured by the temperature sensor 49. Generally, the lower the ambient temperature, the greater the temperature difference between when the heating element is heating and when it is not heating, and the more likely it is to stick together. Therefore, when changing the settings based on the ambient temperature, it is preferable to lower the first threshold and the second threshold as the ambient temperature decreases.

[0064] The determination unit 50 outputs the data of the predicted adhesion occurrence point group (hereinafter referred to as the adhesion occurrence prediction point group data) to the data generation unit 60.

[0065] The data generation unit 60 generates countermeasure data for energizing or de-energizing multiple heating elements 30a during the second power-on control period TB, based on the printing data read from the printing data storage unit 42a of RAM 42 and the adhesion occurrence prediction point group data generated by the determination unit 50.

[0066] In the printing apparatus 10, during a temperature drop period when the likelihood of adhesion is high, the heating element 30a is heated based on countermeasure data that differs from the printing data, thereby suppressing the rapid temperature drop of the thermal head 30 and inhibiting adhesion. The data generation unit 60 generates countermeasure data based on the printing data in the following manner: during the second power-on control period, TB applies voltage to at least a portion of the plurality of heating elements 30a in a set of adhesion countermeasure target point groups, including a predicted adhesion occurrence point group (nth point group).

[0067] The data generation unit 60 includes a dot group number setting unit 61. The dot group number setting unit 61 sets the number of dot groups included in the target dot group set for which voltage is applied to the heating element 30a during the second power-on control period TB, based on countermeasure data. More specifically, the dot group number setting unit 61 sets at least the adhesion occurrence prediction dot group (the nth dot group) as the adhesion countermeasure target dot group set based on printing data. More preferably, the dot group number setting unit 61 sets the adhesion occurrence prediction dot group (the nth dot group) and a predetermined number (at least one) of subsequent dot groups that are continuously printed with the adhesion occurrence prediction dot group as the countermeasure target dot group set based on printing data.

[0068] The dot group number setting unit 61 can also set the number of dot groups included in the dot group set for adhesion countermeasures based on the ambient temperature detected by the temperature sensor 49. Generally, adhesion is more likely to occur at lower ambient temperatures. Therefore, when setting based on ambient temperature, it is preferable to increase the number of dot groups included in the dot group set for adhesion countermeasures as the ambient temperature decreases, thus suppressing a sharp temperature drop caused by the decrease in ambient temperature. As a result, adhesion can be suppressed regardless of the environment in which the printing apparatus 10 is placed. On the other hand, adhesion is less likely to occur in environments with higher ambient temperatures. Therefore, when the ambient temperature is higher than a preset threshold (e.g., 40°C), only the dot group that is predicted to cause adhesion (the nth dot group) can be set as the dot group set for adhesion countermeasures.

[0069] Furthermore, the dot group number setting unit 61 can also set the number of dot groups included in the dot group set for adhesion countermeasures based on printing data. For example, if, in the subsequent dot groups following the dot group that is predicted to cause adhesion (the nth dot group), a sufficient number of heating elements 30a are applied voltage during the first power-on control period, and no temperature drop occurs in the dot groups following the dot group that is predicted to cause adhesion (the nth dot group), it can be determined that the power-on control during the second power-on control period TB can be omitted. Therefore, the dot group number setting unit 61 can also calculate, based on printing data, how many consecutive low-printing-rate dot groups are arranged after the dot group that is predicted to cause adhesion (the nth dot group), and set the number of dot groups included in the dot group set for adhesion countermeasures based on the calculated consecutive number of low-printing-rate dot groups.

[0070] The data generation unit 60 also includes a pattern setting unit 62. The pattern setting unit 62 sets the pattern for each point group of the countermeasure data included in the adhesion countermeasure object point group set.

[0071] Figure 6 This diagram is used to explain the method for determining the cluster of points where adhesion occurs and the method for setting patterns for countermeasure data. Figure 6Taking the case where points Q1-Q8 of the printing area corresponding to each heating element 30a of the thermal head 30 are printed at three gray levels: maximum gray (dark), intermediate gray (light), and no printing (white). The formal power-on data is part of the printing data, representing the printing pattern formed in the group of points to be printed during the first power-on control period TA. Figure 6 In the official power-on data, the case where the heating element 30a heats up corresponding to the maximum grayscale concentration is represented by a black circle, the case where the heating element 30a heats up corresponding to the intermediate grayscale concentration is represented by a gray circle, and the case where the heating element 30a is not heated and printing is set to not proceed is represented by a white circle. Furthermore, in the countermeasure data related to power-on during the second power-on control period TB, the case where the heating element 30a is powered on is represented by a circle with a diagonal line, and the case where the heating element 30a is not powered on is represented by a dashed white circle.

[0072] The determination unit 50 determines whether the nth point group, which is the second point group, corresponds to the point group where adhesion is predicted. For example, the first condition for adhesion occurrence in the previous point group determination unit 51 is set as "the number of points with the largest gray level in the (n-1)th point group is more than two-thirds of the total number of points in the width direction of band 20". In addition, the second condition for adhesion occurrence in the comparison unit 52 is set as "the number of points with the largest gray level in the (n-1)th point group is more than 1.5 times the number of points other than the unprinted points in the nth point group".

[0073] exist Figure 6 In the example, in the formal power-on data of the (n-1)th point group, which is the first point group, the number of points with the maximum gray level is 6, and the total number of points in the width direction of band 20 is 8, so the first condition is satisfied. Furthermore, in the formal power-on data of the (n-1)th point group, the number of points with the maximum gray level is 6, and in the formal power-on data of the nth point group, the number of points other than the non-printed points is 2, so the second condition is satisfied. Therefore, the determination unit 50 determines that the nth point group is a point group for which adhesion is predicted. Next, the determination unit 50 sends the adhesion occurrence prediction point group data targeting the nth point group to the data generation unit 60.

[0074] in addition, Figure 6 This schematically illustrates that the positions of point group (n-1), point group n, point group (n+1), and point group (n+2) differ along the sub-scanning direction. The official power-on data and countermeasure data used for each point group are data for the same printing area along the sub-scanning direction. Figure 6 For convenience, the official power-on data and countermeasure data used by each point group are represented separately.

[0075] The point group number setting unit 61 of the data generation unit 60 sets the nth point group, which is determined to be a point group where adhesion is predicted, and the (n+1)th point group and the (n+2)th point group, which are two consecutive point groups after the nth point group, as the point group set for adhesion countermeasures.

[0076] For the printable area (heating element 30a) of interest, if the official power-on data in the (n-1)th point group corresponds to the maximum grayscale, and the official power-on data in each point group (n, n+1, n+2) of the adhesion countermeasure target point group set is not printed (not powered on), the pattern setting unit 62 generates countermeasure data to power on TB during the second power-on control period. That is, the countermeasure data is generated in such a way that the heating element 30a corresponding to the printable area that has a concentration of 1 or higher in the (n-1)th point group and a concentration of 2 or lower in each point group of the adhesion countermeasure target point group set is powered on TB during the second power-on control period.

[0077] For example, regarding point Q1, each point group (n, n+1, n+2) in the (n-1)th point group and the set of point groups for adhesion countermeasures are the maximum grayscale corresponding to the official power-on data. Therefore, a sharp temperature drop of the heating element 30a in the set of point groups (n, n+1, n+2) for adhesion countermeasures does not occur, so the pattern setting unit 62 does not include point Q1 in the power-on objects during the second power-on control period TB among all the point groups (n, n+1, n+2) in the set of point groups for adhesion countermeasures.

[0078] Regarding point Q2, in the (n-1)th point group and the (n+1)th point group, the formal power-on data corresponds to the maximum gray level, and in the nth point group and the (n+2)th point group, the formal power-on data corresponds to the intermediate gray level. That is, regarding point Q2, there will not be a situation where the next point group printed at the maximum gray level will not be printed. It is presumed that a sharp temperature drop of the heating element 30a will not occur. Therefore, the pattern setting unit 62 does not include point Q2 in the powered objects of the second power-on control period TB in all point groups (n, n+1, n+2) of the adhesion countermeasure object point group set.

[0079] Regarding points Q3 and Q4, in the (n-1)th point group, the actual power-on data corresponds to the maximum grayscale, while in the nth and (n+1)th point groups, the actual power-on data is not printed (no power-on). The large grayscale difference between the (n-1)th and nth point groups is presumably due to a rapid temperature drop in the heating element 30a. Therefore, the pattern setting unit 62 includes points Q3 and Q4 in the power-on objects during the second power-on control period TB for the nth and (n+1)th point groups.

[0080] Furthermore, in the (n+2)th point group, the formal power-on data for points Q3 and Q4 corresponds to the intermediate grayscale. To reduce the likelihood of adhesion during printing of the intermediate grayscale, the heating element 30a is heated. Therefore, the pattern setting unit 62 does not include points Q3 and Q4 in the power-on objects of the second power-on control period TB for the (n+2)th point group.

[0081] Regarding points Q5 and Q6, the official power-on data for the (n-1)th point group corresponds to the maximum grayscale, while the official power-on data for all point groups (n, n+1, n+2) in the adhesion countermeasure object point group set is not printed (not powered on). Therefore, this is a condition where a sharp temperature drop of the heating element 30a is likely to occur. The pattern setting unit 62 includes points Q5 and Q6 in the power-on objects of the second power-on control period TB from all point groups (n, n+1, n+2) in the adhesion countermeasure object point group set.

[0082] Regarding point Q7, the official power-on data for the (n-1)th point group corresponds to the intermediate grayscale. During the first power-on control period TA of all point groups (n, n+1, n+2) in the adhesion countermeasure target point group set, the official power-on data is not printed (no power-on). Regarding point Q7, the (n-1)th point group preceding the nth point group that is not printed is printed at the intermediate grayscale. During the printing of the (n-1)th point group, the heating element 30a does not reach a high temperature, presumably because a subsequent sharp temperature drop does not occur. Therefore, the pattern setting unit 62 does not include point Q7 in the power-on objects of the second power-on control period TB among all point groups (n, n+1, n+2) in the adhesion countermeasure target point group set.

[0083] Regarding point Q8, the official power-on data for the (n-1)th point group and all point groups (n, n+1, n+2) in the set of point groups for adhesion countermeasures is not printed (no power-on). Therefore, a sharp temperature drop in the heating element 30a does not occur, and the pattern setting unit 62 does not include point Q8 in the power-on objects during the second power-on control period TB among all point groups (n, n+1, n+2) in the set of point groups for adhesion countermeasures.

[0084] As described above, the pattern setting unit 62 generates countermeasure data for each dot group. The pattern setting of the countermeasure data performed by the pattern setting unit 62 can be summarized as follows: in each dot group (n, n+1, n+2) of the adhesion countermeasure object dot group set, for the printing area that is printed with the maximum gray level in the previous dot group and is not printed in that row, the heating element 30a is energized during the second power-on control period TB.

[0085] The pattern setting of the countermeasure data performed by the pattern setting unit 62 can be summarized in another way as follows: For printing areas where the heating element 30a is energized by TB during the second power-on control period in the nth point group, and where the density is below the second level in subsequent point groups, the heating element 30a is energized by TB during the second power-on control period in subsequent point groups. Specifically, points Q3 to Q6 of the (n+1)th point group and points Q5 and Q6 of the (n+2)th point group correspond to this. Furthermore, for printing areas where the heating element 30a is energized by TB during the second power-on control period in the nth point group, and where the density exceeds the second level in subsequent point groups, the heating element 30a is not energized by TB during the second power-on control period in subsequent point groups. Specifically, points Q3 and Q4 of the (n+2)th point group correspond to this.

[0086] For points whose official power-on data is at maximum grayscale, even if the heating element 30a is powered on based on countermeasure data after printing at maximum grayscale within a 1-point cycle, the print quality of that point, which has already been printed at maximum grayscale, will not change noticeably and will not have a substantial impact on print quality. In contrast, for points whose official power-on data is at intermediate grayscale, if the heating element 30a is powered on based on countermeasure data within a 1-point cycle, the heating of the heating element 30a may cause the point to become darker than its original print grayscale, potentially affecting print quality.

[0087] In the generation of countermeasure data in the pattern setting unit 62 of this embodiment, for the points corresponding to intermediate gray levels in the formal power-on data during the first power-on control period TA, the heating element 30a is set to be de-energized during the second power-on control period TB. As a result, it is possible to prevent the power-on of the heating element 30a used for adhesion countermeasures during the second power-on control period TB from affecting the printing quality, thus balancing adhesion countermeasures and good printing quality in multi-grayscale printing.

[0088] In addition, Figure 6 In the example, the second power-on control period of TB is not performed for the (n-1)th point group, but the point group number setting unit 61 can also include the (n-1)th point group in the adhesion countermeasure object point group set, and the pattern setting unit 62 can also generate countermeasure data for the (n-1)th point group.

[0089] For example, for Figure 6Points Q3, Q4, Q5, and Q6 are idle for a period of more than one point cycle from the energization of heating element 30a in TA during the first energization control period based on formal energization data in the (n-1)th point group until the energization of heating element 30a in TB during the second energization control period based on countermeasure data in the nth point group. Therefore, by energizing heating element 30a in TB during the second energization control period based on countermeasure data in the (n-1)th point group, the sharp temperature drop of heating element 30a between the (n-1)th point group and the nth point group can be easily suppressed.

[0090] The data generation unit 60 outputs the countermeasure data generated as described above to the head control unit 70.

[0091] The head control unit 70 generates a gating pulse signal and outputs it to the head drive circuit 44. This gating pulse signal is a control signal specifying the energization and de-energization of TA during the first power-on control period and TB during the second power-on control period. More specifically, the head control unit 70 calculates the energization time of TA during the first power-on control period (e.g., based on energization time data read from the energizer stored in ROM 41 and the head temperature measured by the thermistor 31). Figure 4 The energizing times P1-P7 (each) and the energizing time of TB during the second energizing control period (e.g., Figure 4 The energizing time P8). Furthermore, the gating pulse signal (control signal) corresponding to the energizing time, the printed data, and the countermeasure data generated by the data generation unit 60 are output to the head drive circuit 44.

[0092] The printing apparatus 10, configured and controlled as described above, can suppress the rapid temperature drop of the thermal head 30 by controlling the energization of the multiple heating elements 30a in TB during the second energization control period based on countermeasure data. Therefore, adhesion can be suppressed with simple control, and the degradation of print quality caused by adhesion can be avoided.

[0093] In particular, by determining the group of points where adhesion is predicted based on the first and second conditions described above, the determination unit 50 can accurately distinguish the situation where adhesion has occurred. As a result, the implementation of adhesion prevention measures (power supply to the heating element 30a in TB during the second power-on control period) can be suppressed to the minimum required. By minimizing the implementation of adhesion prevention measures, power consumption can be suppressed.

[0094] Furthermore, in conventional control methods, power is sometimes applied to the heating element during the second power-on control period (TB) even when adhesion prevention measures are not required. Although the power application to the heating element during the second power-on control period (TB) is used for temperature adjustment of the thermal head without printing, heating the heating element may affect print quality. Therefore, it is preferable to avoid implementing unnecessary adhesion prevention measures as much as possible. In particular, in printing apparatuses capable of printing at multiple gray levels (three or more), if adhesion prevention measures are applied immediately after printing at an intermediate gray level, the print density may be higher than the original print data.

[0095] In the printing apparatus 10 of this embodiment, based on the determination in the determination unit 50, the implementation of adhesion prevention measures is minimized, and the data generation unit 60 (pattern setting unit 62) generates prevention data with settings that do not affect grayscale performance (no power is applied for adhesion prevention measures when printing at intermediate grayscale levels in the case of formal power-on data). Thus, excellent print quality is achieved by preventing adhesion prevention measures from affecting grayscale performance.

[0096] Figure 7 This is a flowchart of the adhesion countermeasures process in the printing apparatus 10. Figure 8 This is a flowchart of the process for determining the predicted adhesion occurrence point group, which is included in the adhesion countermeasures. (Refer to...) Figure 7 and Figure 8 The process of the adhesion countermeasures performed on the printing apparatus 10 will be explained.

[0097] If printing data is input into the control device 40 of the printing apparatus 10, it will begin. Figure 7 The adhesion countermeasures are shown. First, the determination process for the predicted adhesion point group is performed (step S100).

[0098] The determination and processing of the predicted adhesion point group is handled by... Figure 8 The subroutine shown is executed. The determination unit 50 counts the data "0xff" representing 8 consecutive printed dots contained in the dot group data of each dot group of the printed data, and obtains the number of dots (0xff number) of one dot group (step S200).

[0099] Next, the prior point group determination unit 51 of the determination unit 50 determines whether the proportion of points with a concentration of 1 or higher in the (n-1)th point group preceding the nth point group is greater than or equal to the first threshold (step S201). For example, the number of points with the highest gray level in the (n-1)th point group is compared with the total number of points in the (n-1)th point group, and it is determined whether the number of points in the former is more than 2 / 3 of the number of points in the latter (the first threshold).

[0100] If the determination result in step S201 is "yes" (above the first threshold), the comparison unit 52 of the determination unit 50 determines whether the ratio of the printing area with a concentration of 1 or higher in the (n-1)th point group to the printing area with a concentration of 2 or higher than the first concentration in the nth point group is above the second threshold (step S202). For example, the number of points with the highest gray level in the (n-1)th point group is compared with the number of points other than non-printing points in the nth point group, and it is determined whether the number of points of the former is 1.5 times the number of points of the latter (the second threshold).

[0101] If the determination result in step S202 is "yes" (above the second threshold), the determination unit 50 sets a flag indicating that the nth point group is a predicted adhesion point group (step S203).

[0102] Next, the control device 40 determines whether the nth dot group is the final dot group of the printing data (step S204).

[0103] If the determination result in steps S202 and S203 is "no", the process proceeds directly to step S204 without going through the flag setting in step S203. That is, in these cases, the determination result is that the nth point group is not a predicted adhesion point group.

[0104] If the determination result in step S204 is "no" (not the final point group), the control device 40 performs point group update processing by increasing the number of n by 1 (step S205) and returns to step S200.

[0105] If the determination result in step S204 is "yes" (the final destination group), the control device 40 then... Figure 8 The subroutine is detached and completed. Figure 7 Step S100. In the completion stage of step S100, the state of determining whether each dot group other than the beginning dot group of the printing data is a dot group that is suspected to be sticky.

[0106] Next, the control device 40 expands the formal power-on data of the nth point group (step S101) and determines whether there is a flag indicating the occurrence of a predicted point group after the formal power-on data is expanded (step S102).

[0107] If the determination result in step S102 is "yes" (the nth point group is the predicted adhesion occurrence point group), the data generation unit 60 generates countermeasure data for the adhesion countermeasure target point group set including the nth point group based on the formal power-on data developed in step S101 (step S103).

[0108] In step S103, the number of dot groups included in the dot group set of adhesion countermeasure target dot groups is set by the dot group number setting unit 61. Furthermore, the pattern setting unit 62 generates countermeasure data for each dot group in the adhesion countermeasure target dot group set. Specifically, the pattern setting unit 62 generates the countermeasure data as follows: for dots that are printed at the maximum grayscale in the previous dot group and are not printed in that dot group, the heating element 30a is energized by TB during the second power-on control period.

[0109] If the determination result in step S102 is "No" (the nth point group is not a predicted adhesion occurrence point group), no new countermeasure data is created for the nth point group, and the existing countermeasure data is applied (step S104). That is, if the nth point group is included in the set of adhesion countermeasure target point groups related to the previous point group, the countermeasure data for the nth row that has already been created is applied as is, and combined with the formal power-on data to determine the final point group data for the nth point group. Furthermore, if the nth point group is not included in the set of adhesion countermeasure target point groups related to the previous point group, since there is no countermeasure data related to the nth point group (in other words, countermeasure data where TB does not energize any heating element 30a during the second power-on control period), the formal power-on data is determined as the final point group data for the nth point group.

[0110] After step S103 or step S104, the control device 40 determines whether the nth dot group is the final dot group of the printing data (step S105).

[0111] If the determination result in step S105 is "No" (not the final point group), perform point group update processing by increasing the number of n by 1 (step S106), and return to step S101.

[0112] If the determination result in step S105 is "yes" (the most endpoint group), then the process is complete. Figure 7 The processing. In Figure 7 The processing has been completed, and the data is now in a state where the point groups of printed data have been determined, including countermeasure data.

[0113] By performing the processing along the above flowchart, the implementation of adhesion prevention measures can be minimized, suppressing the impact of adhesion prevention measures on print quality. Furthermore, the power consumption required for adhesion prevention measures can be reduced.

[0114] The printing apparatus 10 of the above embodiment can perform printing of more than three gray levels, but this disclosure can also be applied to printing apparatuses of the type that print with two gray levels.

[0115] Reference Figure 9The method for determining the cluster of adhesion occurrences and the method for setting the pattern of countermeasure data in other types of printing apparatuses that print at two gray levels will be described. These other types of printing apparatuses have the same structure as the printing apparatus 10 of the above embodiment; detailed descriptions of the structure of each part are omitted, and they are indicated by the same reference numerals as those used for the printing apparatus 10.

[0116] exist Figure 9 In the official power-on data, a black circle indicates that the printing will occur when the heating element 30a heats up, while a white circle indicates that the printing will not occur when the heating element 30a does not heat up. Furthermore, in the countermeasure data, a circle with a diagonal line indicates that the heating element 30a is powered on, while a dashed white circle indicates that the heating element 30a is not powered on.

[0117] In the case of printing at two gray levels, the determination unit 50 treats the printed areas in the official power-on data as the printing area of ​​the first density and the unprinted areas as the printing area of ​​the second density. Therefore, the determination unit 50 sets the first condition for adhesion occurrence in the dot group determination unit 51 as "the number of printed dots in the (n-1)th dot group is more than two-thirds of the total number of dots in the width direction of the band 20". In addition, the second condition for adhesion occurrence in the comparison unit 52 is set as "the number of printed dots in the (n-1)th dot group is more than 1.5 times the number of dots other than the unprinted dots in the nth dot group".

[0118] exist Figure 9 In the example, in the formal power-on data of the (n-1)th point group, the number of printed points is 6, and the total number of points in the width direction of 20 is 8, so the first condition is satisfied. Furthermore, in the formal power-on data of the (n-1)th point group, the number of printed points is 6, and in the formal power-on data of the nth point group, the number of points other than those not printed is 2, so the second condition is satisfied. Therefore, the determination unit 50 determines that the nth point group is a point group where adhesion is predicted.

[0119] As described above, by determining the group of points where adhesion is predicted by the determination unit 50, the effect of implementing the adhesion prevention measures can be achieved to the minimum required extent.

[0120] The point group number setting unit 61 of the data generation unit 60 sets the nth point group, which is determined to be a point group where adhesion is predicted, and the (n+1)th point group and the (n+2)th point group, which are two consecutive point groups after the nth point group, as the point group set for adhesion countermeasures.

[0121] Regarding the printable area (heating element 30a) of interest, if the official power-on data in the (n-1)th point group is printing and the official power-on data in the nth point group is no printing (no power-on), the pattern setting unit 62 generates countermeasure data in the nth point group so that TB is powered on during the second power-on control period.

[0122] Furthermore, the pattern setting unit 62 applies the same countermeasure data as the countermeasure data for the (n+1)th point group and the (n+2)th point group, which are subsequent point groups of the nth point group.

[0123] The formal power-on data for the (n+2)th point group differs from that of the nth and (n+1)th point groups, and printing also occurs at points Q3 and Q4 in addition to points Q1 and Q2. Therefore, in the (n+2)th point group, at points Q3 and Q4, after the formal power-on during the first power-on control period TA, power-on for countermeasures is performed during the second power-on control period TB. In the case of two-grayscale printing, for points where the formal power-on data is printed, even if the heating element 30a is powered on based on the countermeasure data within the same 1-point cycle, the printing performance of the already printed point will not change noticeably. Therefore, even if the countermeasure data for the (n+2)th point group is set to be the same as that for the nth and (n+1)th point groups, it will not have a substantial impact on print quality. Furthermore, by sharing the countermeasure data for each point group in the set of sticky countermeasure object point groups, the processing burden for generating the countermeasure data can be reduced.

[0124] The above embodiments are specific examples provided to facilitate understanding of the invention. This disclosure is not limited to these embodiments, and various modifications and alterations can be made without departing from the spirit of the invention.

[0125] For example, in the above embodiment, it is applied to a heat-sensitive printing apparatus 10 that uses a tape 20 containing a color developing layer as the printing medium, but it can also be applied to a heat transfer printing apparatus that heats an ink tape that is transported overlapping with the tape, causing the ink on the tape to adhere to the tape. The heat transfer printing apparatus is described in reference to... Figure 9 This is commonly used in two-grayscale printing devices.

[0126] The printing apparatus 10 of the above embodiment can print on tapes 20 with various widths, but this disclosure can also be applied to printing apparatuses that print only tapes with a fixed width. In this case, the number of heating elements of the thermal head is uniquely determined corresponding to the tape width. Therefore, the second condition for determining the adhesion occurrence prediction point group by the determination unit may not be based on the ratio of the printing area with a first concentration or higher in the (n-1)th point group to the printing area with a second concentration or higher in the nth point group, but rather on the difference in the number of heating elements corresponding to each of these printing areas. Therefore, the comparison result related to the second threshold in this disclosure can be obtained as either the ratio of the printing areas of the two point groups or the difference in the number of heating elements corresponding to the printing areas of the two point groups.

[0127] In the above embodiments, the adhesion countermeasure control was described based on the case where the first point group and the subsequent second point group are continuous. However, this disclosure can also be applied when the first point group and the second point group are not continuous, that is, when the second point group is a point period that is more than two times after the first point group. For example, when the second point group is set as a point period that is two times after the first point group, it can be applied by replacing the (n-1)th point group in the above embodiments with the (n-2)th point group.

[0128] Furthermore, the printing apparatus and printing method disclosed herein are not limited to the above-described embodiments and variations, as long as adhesion is possible.

Claims

1. A printing apparatus, wherein, have: The thermal head has multiple heating elements and prints onto the printing medium in groups of dots, each group of dots consisting of multiple dots corresponding to the multiple heating elements, and is printed based on set printing data. as well as Control device, The above-mentioned control device meets the following conditions: In the first point group, the proportion of the printed area with a specified concentration of 1 or higher is above the first threshold; and If the comparison result between the printed area in the first group of points mentioned above, printed at a printing concentration of the first concentration or higher, and the printed area in the second group, printed at a concentration exceeding the specified second concentration, is a second threshold or higher, The set of dot groups that includes at least the second dot group is designated as the dot group set for which adhesion countermeasures are highly likely to occur. Here, the second dot group refers to a dot group printed later in the time sequence than the first dot group, the second concentration refers to a printing concentration lower than the first concentration, and adhesion is the phenomenon of the thermal head adhering to the printing medium. In addition to the first power-on control period for printing on the printed medium, the control device sets a second power-on control period for preventing adhesion by not printing on the printed medium, and performs power-on control on the thermal head based on countermeasure data. The countermeasure data is used to power on at least a portion of the plurality of heating elements during the second power-on control period for each of the point groups of the adhesion countermeasure target point group set.

2. The printing apparatus as claimed in claim 1, wherein, The aforementioned thermal printhead can print at more than three gray levels. The printing area with the first concentration mentioned above is the printing area with the highest grayscale, while the printing area with the second concentration mentioned above is the non-printing area. The control device generates the countermeasure data in the following manner: in each point group of the set of point groups of the adhesion countermeasure targets, for the printing area that is printed with the maximum gray level in the previous point group and is not printed in the point group, the heating element is energized during the second power-on control.

3. The printing apparatus as claimed in claim 1 or 2, wherein, The first threshold mentioned above is two-thirds of the total printed area of ​​the first point group mentioned above.

4. The printing apparatus as claimed in claim 1 or 2, wherein, The second threshold mentioned above is 1.5 times.

5. The printing apparatus as claimed in claim 1 or 2, wherein, The control device generates the countermeasure data in the following manner: it energizes the heating element that corresponds to the printing area in the first point group that has a concentration of the first concentration or higher and in each point group of the adhesion countermeasure target point group set during the second power-on control.

6. The printing apparatus as claimed in claim 1 or 2, wherein, The control device sets the second dot group and a predetermined number of subsequent dot groups printed continuously from the second dot group as the set of dot groups targeted by the adhesion countermeasure. The control device generates the countermeasure data in the following manner: For the printing area in the second point group above where the heating element is energized during the second power-on control period above, and which is below the second concentration in the subsequent point group above, the heating element is energized during the second power-on control period in the subsequent point group above. For the printing area in the second point group where the heating element is energized during the second power-on control period, and in the subsequent point group where the printing area exceeds the second concentration, the heating element is not energized during the second power-on control period in the subsequent point group.

7. A printing control method for controlling a thermal head having multiple heating elements, printing onto a printable medium in groups of dots, each group of dots consisting of multiple dots corresponding to the multiple heating elements, and printing based on preset printing data, wherein... Under the following conditions: In the first point group, the proportion of the printed area with a specified concentration of 1 or higher is above the first threshold; and If the comparison result between the printed area in the first group of points mentioned above, printed at a printing concentration of the first concentration or higher, and the printed area in the second group, printed at a concentration exceeding the specified second concentration, is a second threshold or higher, The set of dot groups that includes at least the second dot group is designated as the dot group set for which adhesion countermeasures are highly likely to occur. Here, the second dot group refers to a dot group printed later in the time sequence than the first dot group, the second concentration refers to a printing concentration lower than the first concentration, and adhesion is the phenomenon of the thermal head adhering to the printing medium. Outside of the first power-on control period for printing on the aforementioned printable medium, a second power-on control period is set to prevent printing on the aforementioned printable medium in order to prevent adhesion. Power-on control of the aforementioned thermal head is performed based on countermeasure data, which is used to power on at least a portion of the aforementioned plurality of heating elements during the aforementioned second power-on control of each point group in the aforementioned set of adhesion countermeasure target point groups.

8. A computer-readable, non-transitory storage medium, wherein, A program is stored that causes a computer mounted on a printing apparatus equipped with a thermal head to perform the following processing: the thermal head has multiple heating elements, and printing is performed on the printing medium in groups of dots, each group of dots consisting of multiple dots corresponding to the multiple heating elements, and printing is performed based on set printing data. The processing is as follows: Under the following conditions: In the first point group, the proportion of the printed area with a specified concentration of 1 or higher is above the first threshold; and If the comparison result between the printed area in the first group of points mentioned above, printed at a printing concentration of the first concentration or higher, and the printed area in the second group, printed at a concentration exceeding the specified second concentration, is a second threshold or higher, The set of dot groups that includes at least the second dot group is designated as the dot group set for which adhesion countermeasures are highly likely to occur. Here, the second dot group refers to a dot group printed later in the time sequence than the first dot group, the second concentration refers to a printing concentration lower than the first concentration, and adhesion is the phenomenon of the thermal head adhering to the printing medium. Outside of the first power-on control period for printing on the aforementioned printable medium, a second power-on control period is set to prevent printing on the aforementioned printable medium in order to prevent adhesion. Power-on control of the aforementioned thermal head is performed based on countermeasure data, which is used to power on at least a portion of the aforementioned plurality of heating elements during the aforementioned second power-on control of each point group in the aforementioned set of adhesion countermeasure target point groups.

9. A computer program product, wherein, A computer mounted on a printing apparatus equipped with a thermal head performs the following processing, wherein the thermal head has multiple heating elements, and printing is performed on the printing medium in groups of dots, each group of dots consisting of multiple dots corresponding to the multiple heating elements, and printing is performed based on set printing data. The processing is as follows: Under the following conditions: In the first point group, the proportion of the printed area with a specified concentration of 1 or higher is above the first threshold; and If the comparison result between the printed area in the first group of points mentioned above, printed at a printing concentration of the first concentration or higher, and the printed area in the second group, printed at a concentration exceeding the specified second concentration, is a second threshold or higher, The set of dot groups that includes at least the second dot group is designated as the dot group set for which adhesion countermeasures are highly likely to occur. Here, the second dot group refers to a dot group printed later in the time sequence than the first dot group, the second concentration refers to a printing concentration lower than the first concentration, and adhesion is the phenomenon of the thermal head adhering to the printing medium. Outside of the first power-on control period for printing on the aforementioned printable medium, a second power-on control period is set to prevent printing on the aforementioned printable medium in order to prevent adhesion. Power-on control of the aforementioned thermal head is performed based on countermeasure data, which is used to power on at least a portion of the aforementioned plurality of heating elements during the aforementioned second power-on control of each point group in the aforementioned set of adhesion countermeasure target point groups.

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