Printer, printing control method, storage medium

Abstract

One aspect of the present invention is a printer that prints on a printing medium, comprising: a thermal head having a plurality of heating elements arranged in a row; and a control unit that controls the thermal energy applied to the plurality of heating elements based on image data according to whether or not an energization pulse is applied during a plurality of periods preset for one printing cycle. Among them, during the printing cycle, the plurality of periods are set in order from a long period to a short period.

Description

Technical Field

[0001] The present invention relates to a printer, a printing control method, and a storage medium. Background Art

[0002] Generally, by causing a prescribed current to flow through a plurality of heating elements arranged in a row, the thermal head is heated, and information is printed by forming a dot pattern on a printing medium having, for example, a thermosensitive coloring layer. At this time, the coloring of a dot corresponding to the heating element is controlled according to the time during which the current flows through the heating element (i.e., the energization pulse width).

[0003] In addition, it is known that since the thermal head has a heat storage characteristic that heat accumulates in the heating element if the same heating element is continuously energized, heat history control is performed in which the energization pulse width is adjusted according to the energization history of the heating element so that the thermal energy applied to the heating element becomes constant (for example, Japanese Patent Application Laid-Open No. 2017-42936).

[0004] However, in Japanese Patent Application Laid-Open No. 2017-42936, it is described that the conduction (on) time of the heating element corresponding to the pixel of the print data of the current row is controlled according to the heat history pattern, but efficient application of thermal energy to the heating element is not considered. For example, in the case of how to set (allocate) the conduction time during the printing cycle of one row after the conduction time of the heating element is determined, the above publication does not describe it. Summary of the Invention

[0005] Therefore, an object of the present invention is to efficiently apply thermal energy to the heating elements of a thermal head.

[0006] A certain aspect of the present invention is a printer that prints on a printing medium, comprising:

[0007] a thermal head having a plurality of heating elements arranged in a row; and

[0008] a control unit that controls the thermal energy applied to the plurality of heating elements based on image data according to whether an energization pulse is applied during a plurality of periods preset in a printing cycle of one row,

[0009] in the printing cycle, the plurality of periods are set in order from a long period to a short period.

[0010] According to a certain aspect of the present invention, it is possible to efficiently apply thermal energy to the heating elements of a thermal head. Brief Description of the Drawings

[0011] Figure 1 It is a schematic cross-sectional view of a printer for explaining a printing operation performed by a printer according to one embodiment.

[0012] Figure 2 is a functional block diagram of a printer according to one embodiment.

[0013] Figure 3 is a functional block diagram focusing on the control unit and the thermal head in a printer according to one embodiment.

[0014] Figure 4 is a schematic circuit diagram of a thermal head according to one embodiment.

[0015] Figure 5 is a diagram showing the relationship between the selected voltage level and the timing at which current substantially flows through the heating element during each period when a strobe signal is applied in the thermal history control according to one embodiment.

[0016] Figure 6 is a diagram showing an example of a thermal history data table.

[0017] Figure 7 is showing Figure 6 a diagram of an example of the thermal history data table and the application pattern of the strobe signal.

[0018] Figure 8 is a timing diagram showing the transfer timing of the data signal and the application timing of the strobe signal during the printing cycle in a printer according to one embodiment.

[0019] Figure 9 is a timing diagram showing the transfer timing of the data signal and the application timing of the strobe signal during the printing cycle in a comparative example. Detailed Embodiments

[0020] In Figure 1 , a printer 1 according to one embodiment is illustrated. The printer 1 is a direct thermal type thermal printer that prints on a label having a thermal color developing layer on one side.

[0021] As Figure 1 shown, the printer 1 includes a roll paper storage chamber 9, a paper feed roller 10, a thermal head 15, a printer cover 25, a spiral spring 29, and the like. The roll paper R can be loaded into the roll paper storage chamber 9 by opening and closing the printer cover 25.

[0022] The roll paper R is a roll paper in which a strip-shaped continuous paper P is wound into a roll shape. Although not shown, in one embodiment, the continuous paper P has, for example, a strip-shaped backing paper and a plurality of labels temporarily adhered to the backing paper at predetermined intervals. On the label adhesion surface of the backing paper, it is covered with a release agent such as silicone so that the label can be easily peeled off.

[0023] In other embodiments, the continuous paper P may also be a label without a backing paper.

[0024] As shown Figure 1 in FIG. Figure 1 , the paper pressing roller 10 is supported by the printer 1 in a state where it can rotate in both forward and reverse directions. The paper pressing roller 10 is a conveying unit for conveying the continuous paper P pulled out from the roll paper R, and is formed in a state extending along the width direction of the continuous paper P. A gear (not shown) is provided at one end of the paper pressing shaft of the paper pressing roller 10, and this gear is mechanically connected to a stepping motor (not shown) for driving the roller. Corresponding to the rotation of the stepping motor that operates based on a signal sent from a circuit board (not shown), the paper pressing roller 10 rotates.

[0025] The thermal head 15 is a printing unit that prints information such as characters, symbols, graphics, or barcodes on the label on the continuous paper P. The thermal head 15 includes a plurality of heating elements (heating resistors) arranged along the width direction of the continuous paper P, and performs printing by selectively energizing the plurality of heating elements based on a signal sent from the circuit board.

[0026] When the printer cover 25 is in the closed state, the thermal head 15 is disposed opposite to the paper pressing roller 10 and clamps the continuous paper P together with the paper pressing roller 10. The spiral spring 29 is a biasing unit that biases the thermal head 15 toward the paper pressing roller 10, and generates a clamping pressure suitable for printing between the thermal head 15 and the paper pressing roller 10.

[0027] In the following description, the direction orthogonal to the conveying direction of the continuous paper P (i.e., the direction in which the heating elements are arranged) is referred to as the "main scanning direction", and the direction the same as the conveying direction of the continuous paper P is referred to as the "sub-scanning direction".

[0028] The thermal head 15 will be described in detail later.

[0029] Next, refer to Figure 2 the internal structure of the printer 1. Figure 2 is a block diagram showing the internal structure of the printer 1.

[0030] As shown Figure 2 in FIG. Figure 2 , the printer 1 includes, for example, a control unit 11, a storage unit 12, a drive circuit 13, a motor 14 mechanically connected to the paper pressing roller 10, a thermal head 15, and a communication interface (I / F) 16.

[0031] The control unit 11 includes a controller and a memory, and controls the operation of the printer 1. The processor reads and executes the firmware stored in the ROM when the printer 1 is started.

[0032] The controller includes a CPU (Central Processing Unit) as described later, and performs control by executing the firmware so that the thermal head 15 prints specified information on the label.

[0033] The storage unit 12 is a storage device such as an SSD (Solid State Drive). In the storage unit 12, files for printing obtained from a host computer via the communication interface 16 are stored, for example. The storage unit 12 may also store information on the printing format when printing information on each label.

[0034] The drive circuit 13 is a circuit that drives a motor 14 that controls the rotation of the paper feed roller 10 according to a conveyance request from the control unit 11. The motor 14 is, for example, a stepper motor. The conveyance request includes, for example, information on the conveyance direction (forward or reverse direction) and the conveyance amount (for example, the number of steps).

[0035] The control unit 11 performs a printing process by controlling the current to selectively flow through each of the plurality of heating elements included in the thermal head 15 based on the image data to be printed. The image data is data that depicts a file for printing as bitmap data. When the heating element of the thermal head 15 that is heated by the current is pressed against a label on the continuous paper P conveyed by the paper feed roller 10, the thermosensitive coloring layer of the label against which the heating element is pressed is colored, thereby printing information on the label.

[0036] The communication interface 16 includes, for example, a communication circuit for communicating with an external device such as a host computer.

[0037] Next, with reference to Figure 3 and Figure 4 the printing operation of the printer 1 will be described. Figure 3 is a functional block diagram of the control unit and the thermal head in the printer 1 focusing on one embodiment. Figure 4 is a schematic circuit diagram of the thermal head 15 in one embodiment.

[0038] As Figure 3 shown, the control unit 11 is configured to include a CPU 111, a head controller 112, and a memory 113 (an example of a storage unit), and each unit can communicate via a bus 114.

[0039] The CPU 111 controls the overall printing operation in the control unit 11. The head controller 112 supplies various signals for printing to the thermal head 15 under the control of the CPU 111.

[0040] The signals supplied to the thermal head 15 by the head controller 112 include a clock pulse CLK, a latch pulse LATCH, a data signal DATA, and a strobe signal STB.

[0041] The memory 113 is, for example, a RAM (Random Access Memory), and includes an image buffer, a line buffer, and a thermal history data table having a FIFO (First In First Out) structure.

[0042] The CPU 111 performs thermal history control to execute printing. The thermal history control refers to the control of adjusting the energization pulse width (i.e., the width of the strobe signal STB; hereinafter, appropriately referred to as the "strobe application period") based on the data of past energization of the heating element and / or the predetermined data of energization of the heating element, so that the thermal energy for the heating element becomes constant.

[0043] To perform the thermal history control, the CPU 111 generates data obtained by changing the original image data (hereinafter referred to as "thermal history reflection data") based on the print data of the points of interest in the image data that is the original print object and the print data of the points around the points. The thermal history reflection data is stored in the image buffer.

[0044] In the following description, the "image data" refers to the original image data before being changed to the thermal history reflection data.

[0045] In the thermal history control, in one print cycle (i.e., the print cycle of one line), multiple data signals and multiple strobe signals corresponding to the respective data signals are generated. In the example described later, in one print cycle, 4 data signals and strobe signals are generated. In this case, for example, in the thermal head 15, M heating elements are arranged in a row, and when the data of one line (line data) of the image data is M bits, the data of one line (line data) of the thermal history reflection data is M×4-bit data.

[0046] In the line data of the image data, print data indicating whether to print each point (an example of information on whether to print) is included. The print data is either "print" or "non-print".

[0047] On the contrary, the data for each point in the line data of the thermal history reflection data corresponding to one line data of the image data corresponds to multiple data signals and becomes data indicating either "energization" or "non-energization".

[0048] The line data of the thermal history reflection data is sequentially stored in the line buffer.

[0049] As described above, the thermal history data table is referred to when generating the thermal history reflection data. The thermal history data table will be described in detail later.

[0050] The head controller 112 generates a data signal DATA based on the row data sequentially transferred from the line buffer, and generates a strobe signal STB at a specified timing. In addition, the transfer of the row data from the line buffer to the head controller 112 is performed, for example, by DMA (Direct Memory Access).

[0051] The thermal head 15 includes a drive circuit 2 and a heating element group 3.

[0052] The heating element group 3 is composed of a plurality of heating elements (heating resistor bodies) arranged in a row.

[0053] The drive circuit 2 selectively passes a current through each heating element of the heating element group 3 based on various signals supplied from the head controller 112 to cause the heating element to generate heat.

[0054] A detailed structural example of the drive circuit 2 and the heating element group 3 will be described later.

[0055] As Figure 4 shown, the drive circuit 2 of one embodiment includes at least a shift register (S / R) 21 for temporarily storing one row amount of the data signal DATA, a latch circuit (L) 22, a gate circuit group 23, and a transistor group 24.

[0056] The heating element group 3 includes heating elements (heating resistor bodies) 31_1 to 31_M.

[0057] The drive circuit 2 operates using the data signal DATA, a clock pulse CLK, a latch pulse LATCH, and the strobe signal STB, but these data and signals are input or transferred from the head controller 112. To shorten the transfer time, the transfer of one row amount of the data signal DATA can also be performed by dividing and transferring it using a plurality of line buffers. In this case, a divided part of one row amount of the data signal DATA is stored in each line buffer, and serial transfer is performed from each line buffer.

[0058] In addition, in Figure 4 the drive circuit 2, the strobe signal STB is positive logic (current flows through the heating element at a high level to cause the heating element to generate heat). In other embodiments, the strobe signal STB can also be negative logic (current flows through the heating element at a low level to cause the heating element to generate heat).

[0059] Synchronously with the clock pulse CLK, one-line amount of data signal DATA is input and held in the shift register 21. Further, the data signal DATA (an example of a power-on pulse) is composed of bit columns that are high level when "power-on" and low level when "not power-on". The latch circuit 22 is connected in parallel with the shift register 21 and simultaneously transfers and holds the bit columns on the shift register 21 in parallel. The transfer timing of data from the shift register 21 to the latch circuit 22 is controlled by the latch pulse LATCH.

[0060] The gate circuit group 23 includes gate circuits (AND circuits) 23_1, 23_2, …, 23_M corresponding to the first to M-th points of one line respectively. The strobe signal STB is supplied to one input terminal of each gate circuit, and the other input terminal of each gate circuit is connected to the output terminal of the latch circuit 22.

[0061] Each gate circuit of the gate circuit group 23 outputs the logical product of the corresponding data signal DATA and the strobe signal STB.

[0062] The transistor group 24 includes MOS transistors 24_1 to 24_M. Each MOS transistor is turned on / off according to the output of the corresponding gate circuit.

[0063] During the period when the strobe signal STB is high level, the logical level of the output terminal of each gate circuit of the gate circuit group 23 is the same as the output level of the latch circuit 22. For example, when the output level of the latch circuit 22 is high level indicating "power-on", the output of the corresponding gate circuit becomes high level, so the corresponding MOS transistor is turned on and current flows through the heating element 31. On the contrary, when the output level of the latch circuit 22 is low level indicating "not power-on", the output of the corresponding gate circuit becomes low level, so the corresponding MOS transistor is turned off and no current flows through the heating element 31.

[0064] Further, when the strobe signal STB is of negative logic, it can be configured as follows.

[0065] That is, in Figure 4 , each gate circuit of the gate circuit group 23 is made a NAND circuit, and the inverted signal of the strobe signal STB is input to the NAND circuit. Thereby, when the strobe signal STB is low level, the NAND circuit outputs the inverted signal of the output of the latch circuit 22. The corresponding MOS transistor is configured to be turned on when the output of the NAND circuit is low level, so that current flows through the heating element.

[0066] Without performing thermal history control, for the line data of one line amount, during the printing cycle, the data signal DATA is sent once to the drive circuit 2 of the thermal head 15. In contrast, in the case of performing thermal history control, for the line data of one line amount, during the printing cycle, the data signal DATA (for example, the data signals DATA_1 to DATA_4 described later) is sent to the drive circuit 2 of the thermal head 15 during multiple periods.

[0067] In the thermal history control of one embodiment, during the printing cycle, at a specified timing synchronized with the clock pulse CLK, the head controller 112 supplies the four data signals DATA_1 to DATA_4 to the drive circuit 2.

[0068] When one line of image data is M bits, the line data corresponding to the thermal history reflection data becomes data of M×4 bits. Each M-bit of this M×4-bit data is divided into four times and supplied to the drive circuit 2 as the data signals DATA_1 to DATA_4.

[0069] The head controller 112 supplies the lock pulse LATCH and the strobe signals STB_1 to STB_4 to the drive circuit 2 of the thermal head 15 at a specified timing synchronized with the clock pulse CLK. The relationship between the transfer timing of the data signal and the application timing of the strobe signal in one printing cycle when performing thermal history control will be described later.

[0070] Next, the thermal history data table will be described in further detail.

[0071] The thermal history data table represents the applied data of the processing target points (hereinafter referred to as "concerned points") in the printing target line (hereinafter referred to as "concerned line") in the image data, the printing data of the points corresponding to the concerned points in the front and rear lines of the concerned line (that is, past printing data, future printing data), and the relationship with the strobe level for the concerned points in the printing cycle.

[0072] Here, the strobe level represents the level (high level or low level) of each data signal during multiple strobe application periods for the heating element corresponding to the concerned point. The level of the data signal represents whether a power-on pulse is applied during each strobe application period. The strobe level represents the length of time when current substantially flows through the heating element in the printing cycle. The larger the strobe level, the longer the current flows through the heating element in the printing cycle, so more thermal energy is given to the heating element.

[0073] The CPU 111 refers to the thermal history data table and determines the levels of the respective data signals (high level indicating "power on" or low level indicating "power off") for each of the multiple strobe application periods for the points of the concerned line. Thereby, considering the print data of the current concerned point and the print data before and after it, the heat energy given to the heating element corresponding to the current concerned point is appropriately controlled.

[0074] In the thermal history data table of other embodiments, it also includes the relationship between the respective print data of the points adjacent to the concerned point and the strobe on level for the concerned point in the print cycle. By referring to the print data of the points adjacent to the left and right of the concerned point, the heat energy received by the heating element corresponding to the concerned point from the adjacent heating elements can be considered, so that the heat energy given to the heating element corresponding to the current concerned point can be controlled more appropriately.

[0075] In the following description, the past print data of the concerned point refers to the data of the points located before the concerned point in the sub-scanning direction and is appropriately referred to as "past data".

[0076] The future print data of the concerned point refers to the data of the points located after the concerned point in the sub-scanning direction and is appropriately referred to as "future data".

[0077] Figure 5 It shows the relationship between the strobe on level (STB level) in the thermal history control of one embodiment and the timing when current substantially flows through the heating element during each of the periods when the strobe signals STB_1 to STB_4 are applied in the print cycle.

[0078] In the case of a thermal head with positive logic, substantially flowing current through the heating element means that the corresponding data signals DATA_1 to DATA_4 are at a high level. That is, the data signals DATA_1 to DATA_4 correspond to the strobe on level.

[0079] For example, the data signals DATA_1 to DATA_4 corresponding to the concerned point become 4-bit data corresponding to the strobe on level. For example, the data signals DATA_1 to DATA_4 are "0000" when the strobe on level is "0", "0110" when the strobe on level is "6", and "1111" when the strobe on level is "15".

[0080] In one embodiment, when the strobe on level is 4 or more, heat energy that causes the thermosensitive coloring layer of the label to change color is given to the heating element, and when the strobe on level is less than 4, heat energy that causes the thermosensitive coloring layer of the label to change color is not given to the heating element, but a preheating effect on the heating element is exerted.

[0081] In one embodiment, as Figure 5As shown, during the printing cycle, four strobe signals STB_1 to STB_4 corresponding to four data signals are set in the order from the longest period to the shortest period. That is, if the lengths of the four strobe signals STB_1 to STB_4 are L1 to L4 respectively, then L1 > L2 > L3 > L4. The advantages of such a setting will be described later.

[0082] Preferably, the length ratio of the four strobe signals STB_1 to STB_4 is 8:4:2:1. By setting the length ratio in this way, the number of combinations of the time for supplying thermal energy to the heating element (i.e., the energization time of the heating element; referred to as "strobe length") in one printing cycle can be increased as much as possible, and a fine energy application setting can be performed. The length ratio of the four strobe signals STB_1 to STB_4 is not limited to 8:4:2:1, but by setting them to different lengths respectively, 16 (= 2 4 ) kinds of strobe length patterns with different strobe lengths can be set.

[0083] The exemplified thermal history data table is shown in Figure 6 below.

[0084] In Figure 6 , the focus points refer to each point of the row data (referred to as "focus row data") of the focus row in the image data when generating the thermal history reflection data.

[0085] Figure 6 The thermal history data table of shows the selected energization levels set for the current focus point, the past data of the previous 1 focus point, the past data of the previous 2 focus points, the future data of the next 1 focus point, and the future data of the next 2 focus points in the focus row data, corresponding to the combinations of the respective print data (●: "printed", 〇: "not printed").

[0086] In Figure 6 , the front and back point pattern 101 represents 32 (= 2 5 ) kinds of combination patterns of the print data corresponding to the past data of the previous 1 focus point (represented by "-1"), the past data of the previous 2 focus points (represented by "-2"), the future data of the next 1 focus point (represented by "+1"), and the future data of the next 2 focus points (represented by "+2") of the current focus point.

[0087] In one embodiment, when generating the thermal history reflection data, the points adjacent to the left and right of the current focus point are also considered.

[0088] In Figure 6 , the adjacent point pattern 102 represents 4 (= 2 2 ) kinds of combination patterns of the print data of the points adjacent to the left and right of the current focus point.

[0089] InFigure 6 Among them, the selected power level data 103 represents the selected power level (any value from 0 to 15) for each of the 32×4 combinations based on the front and rear point pattern 101 and the adjacent point pattern 102 for the current focus.

[0090] Figure 7 Represents for Figure 6 Among the 32×4 combinations shown, when the print data of the left and right points adjacent to the current focus are both "printed" (●), it is the timing when current substantially flows through the heating element during the application of each strobe signal. The relationship between the selected power level corresponding to each pattern determined by the selected power level data 103 and the timing when current substantially flows through the heating element is the same as that Figure 5 shown.

[0091] For each focus of the focus line data, the CPU 111 refers to the thermal history data table exemplified in Figure 6 and determines the selected power level according to the selected power level data 103. The CPU 111 generates thermal history reflection data by allocating 4-bit data corresponding to the selected power level to each focus.

[0092] For each focus of the row data of the thermal history reflection data, the head controller 112 allocates the data of the 1st bit to the 4th bit to the data signals DATA_1 to DATA_4 respectively.

[0093] Next, refer to Figure 8 and Figure 9 to illustrate the transfer timing of the data signal and the application timing of the strobe signal when performing thermal history control for printing.

[0094] Figure 8 is a timing chart showing the transfer timing of the data signal and the application timing of the strobe signal in the print cycle SLT in the printer 1 of one embodiment. Figure 9 is a timing chart showing the transfer timing of the data signal and the application timing of the strobe signal in the print cycle SLT in the comparative example.

[0095] In Figure 8 and Figure 9 a standby time WT is set between consecutive strobe application periods.

[0096] In addition, in Figure 8 and Figure 9 in each timing chart, "no correction" represents the timing chart when printing at the standard print density. In Figure 8 and Figure 9 in each timing chart, "correction (-)" and "correction (+)" respectively represent the timing charts after timing correction when printing at a print density lower than the standard and higher than the standard.

[0097] In the timing correction corresponding to the printing density, the length of each strobe signal in the standard printing density is multiplied by a prescribed proportional constant corresponding to the printing density set in the printer 1 (a positive value less than 1 in the case of correction (-) and a value greater than 1 in the case of correction (+)) to determine the length of each corrected strobe signal. In Figure 8 and Figure 9 each timing chart, the timing correction is performed in such a way that the final strobe application period converges within the period SLT.

[0098] As Figure 8 shown, in one embodiment, four strobe signals STB_1 to STB_4 corresponding to four data signals DATA_1 to DATA_4 are set in the order from the long period to the short period. In contrast, in Figure 9 the comparative example shown, three strobe signals STB_1 to STB_3 corresponding to three data signals DATA_1 to DATA_3 are set in the order from the short period to the long period.

[0099] By setting a plurality of strobe signals within the printing period SLT in the order from the long period to the short period as Figure 8 shown, the following advantageous effects can be obtained as compared with Figure 9 the comparative example shown.

[0100] (i) For example, in Figure 8 , the long-period strobe signals STB_1 and / or STB_2 are set for the purpose of printing, and the short-period strobe signals of the strobe signals STB_3 and / or STB_4 are set for the purpose of preheating. By arranging the strobe signals set for the purpose of preheating near the end of the printing period SLT, the time until the strobe signal for printing in the next printing period SLT becomes short, and the preheating efficiency can be improved. If the period until the strobe signal for printing in the next printing period SLT is long for the strobe signal set for the purpose of preheating, the heating element to which the preheating is applied during that period will cool, and thus the preheating effect cannot be fully exerted. In contrast, in Figure 8 , since the period until the strobe signal for printing in the next printing period SLT is relatively short for the strobe signal set for the purpose of preheating, it is possible to prevent the heating element to which the preheating is applied during that period from cooling, and the preheating effect can be exerted. That is, the preheating efficiency can be improved.

[0101] (ii) By arranging them in order starting from the long-period strobe signal within the printing period SLT, the standby time WT is short and the data transfer efficiency is good.

[0102] Refer to Figure 9, since the length of the initial strobe signal STB_1 in the print cycle SLT is shorter than the data transfer time of the data signal DATA_2, in order to make the next strobe signal STB_2 high level, a relatively long standby time WT is generated to standby during the data transfer time of the data signal DATA_2. Similarly, since the length of the strobe signal STB_2 is shorter than the data transfer time of the data signal DATA_3, in order to make the next strobe signal STB_3 high level, a relatively long standby time WT is generated to standby during the data transfer time of the data signal DATA_3. In Figure 9 In the comparative example shown, the data signal is transmitted three times, but in the case of transmitting the data signal four times Figure 8 similarly, more standby time WT is generated.

[0103] In contrast, as Figure 8 shown, if the long-duration strobe signals are sequentially arranged within the print cycle SLT, multiple strobe application periods can be concentratedly arranged, and the standby time WT can be shortened. In other words, the time from the start time of the initial strobe application period to the end time of the last strobe application period in multiple strobe application periods can be shortened, thereby reducing the ratio of this time to the print cycle SLT. Additionally, from another perspective, the ratio of the time occupied by the strobe application period in the time from the start time of the initial strobe application period to the end time of the last strobe application period in multiple strobe application periods can be increased.

[0104] (iii) By sequentially arranging from the long-duration strobe signal within the print cycle SLT, the standby time WT becomes shorter and the thermal energy control is stable.

[0105] During the standby time WT, the heating element is cooled, but when the standby time WT is long, it is difficult to predict to what extent the heating element is cooled. Therefore, there are cases where the expected effect of the strobe signal for preheating cannot be obtained.

[0106] In addition, in the Figure 8 timing diagram, the change in the standby time WT with respect to the concentration correction is relatively small. In contrast, in the Figure 9 timing diagram, the change in the standby time WT with respect to the concentration correction is relatively large. This is because in the Figure 9 timing diagram, the lengths of the initially arranged strobe signals STB_1 and STB_2 in the print cycle SLT are shorter than the data transfer time of the data signal. That is, as Figure 9 shown, when sequentially arranging from the short-duration strobe signal within the print cycle SLT, the deviation of the standby time WT becomes larger, and there is a problem of unstable thermal energy control of the heating element.

[0107] Conversely, as Figure 8 shown, by sequentially arranging starting from the long-period strobe signal within the print cycle SLT, it has the advantages of being easy to predict the preheating effect and having stable thermal energy control for the heating elements.

[0108] The print control method of one embodiment is executed in the control unit 11 and includes the following steps (a) and (b).

[0109] Step (a): Sequentially transfer the line data of the image data; and

[0110] Step (b): Based on the print data of the points of interest in the print object line and the print data of the points corresponding to the above-mentioned points of interest in the lines before and after the line of interest, determine whether to apply the respective DATA signals (energization pulses) of the multiple strobe application periods for each point of the line of interest.

[0111] Here, in step (b), within the print cycle, the multiple strobe application periods are set in the order from long period to short period.

[0112] The program of one embodiment is a program that causes a computer to execute the above-mentioned print control method. For example, the above-mentioned print control method is executed by the CPU 111 included in the control unit 11 of the printer 1 by executing the program.

[0113] In one embodiment, this program can also be recorded on a non-temporary computer-readable recording medium.

[0114] In one embodiment, the printer may not be a direct thermal type thermal printer that prints on a label having a thermosensitive color developing layer, but a thermal transfer printer that transfers the ink coated on the ink ribbon to the label by the heat of the thermal head. That is, the above-mentioned method for controlling the thermal energy of the multiple heating elements of the thermal head can also be applied to a thermal transfer printer.

[0115] The above has described in detail the embodiments of the printer, print control method, and program of the present invention, but the scope of the present invention is not limited to the above embodiments. In addition, the above embodiments can be variously improved or changed without departing from the gist of the present invention.

[0116] In the above embodiment, an example in which the strobe application period is set 4 times during the print cycle is described, but it is not limited thereto, and it can also be 5 times or more. By increasing the number of strobe application periods, more strobe levels can be set, and more precise control can be performed.

[0117] The present invention relates to the patent application of Japanese Patent Application No. 2021-21445 filed with the Japan Patent Office on February 15, 2021, and the entire content of this application is incorporated into this specification by reference.

Claims

1. A printer that prints on a printing medium, wherein the printer is characterized by comprising: a thermal head having a plurality of heating elements arranged in a row; and a control unit that controls the thermal energy applied to the plurality of heating elements based on image data according to whether or not an energization pulse is applied during a plurality of periods preset for one line printing cycle, in the printing cycle, the plurality of periods are set in the order from a long period to a short period, the plurality of periods have 4 periods with a length ratio of 8:4:2:

1.

2. The printer according to claim 1, wherein the length of the shortest period among the plurality of periods is the length at which the printing medium does not develop color when an energization pulse is applied during this period.

3. The printer according to claim 1, wherein the length of the shortest period among the plurality of periods is shorter than the time for transferring the image data for one line amount.

4. The printer according to any one of claims 1 to 3, wherein when the control unit adjusts the printing density, within one line printing cycle, the length of each period of the plurality of periods is a value obtained by multiplying the corresponding length without adjusting the printing density by the same proportional constant.

5. The printer according to any one of claims 1 to 3, wherein the printer has a storage unit that stores information on whether or not there is printing at a focus point in a printing target line, information on whether or not there is printing at points corresponding to the focus point in the lines before and after the printing target line, and pulse application information corresponding to whether or not an energization pulse of each period of the plurality of periods is applied to the heating element corresponding to the focus point, the control unit refers to the pulse application information and determines whether or not to apply an energization pulse of each period of the plurality of periods to each point of the printing target line.

6. The printer according to claim 5, wherein in the pulse application information, further corresponding information on whether or not there is printing at each point adjacent to the focus point and whether or not an energization pulse of each period of the plurality of periods is applied to the heating element corresponding to the focus point is established.

7. A printing control method for a printer that prints on a printing medium by a thermal head having a plurality of heating elements arranged in a row, wherein the printing control method is characterized in that in one line printing cycle, a plurality of periods are preset, the printing control method includes the following steps, namely: sequentially transferring the data of each line of the image data; and determining whether or not to apply an energization pulse of each period of the plurality of periods to each point of the printing target line based on information on whether or not there is printing at a focus point in the printing target line and information on whether or not there is printing at points corresponding to the focus point in the lines before and after the printing target line, in the printing cycle, the plurality of periods are set in the order from a long period to a short period, the plurality of periods have 4 periods with a length ratio of 8:4:2:

1.

8. A storage medium stores a program that causes a computer to execute a prescribed method for printing on a print medium using a thermal head having a plurality of heating elements arranged in a line shape. The storage medium is characterized in that in a print cycle of one line, a plurality of periods are preset. The method includes the following steps, namely: successively transferring data of each line of image data; and determining whether to apply energization pulses of each of the plurality of periods to each point of the print target line based on information on whether there is printing at a point of interest in the print target line and information on whether there is printing at a point corresponding to the point of interest in the lines before and after the print target line. In the print cycle, the plurality of periods are set in the order from a long period to a short period. The plurality of periods have four periods with a length ratio of 8:4:2:1.

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