JP2011251472A - Thermal printer and control program for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal printer capable of stabilizing printing speed and obtaining successful printing results even when electric current is supplied to a heating element in time division to print one line.SOLUTION: The thermal printer includes a printing data storage means, a printing rate detection means, a first division number detection means, a speed detection means, a speed change means and a second division number detection means. The printing rate detection means detects a printing rate of each line of printing data stored in the printing data storage means, and the first division number detection means detects a division number during printing of each line based on the detected printing rate. The speed detection means detects printing speed of each line based on the detected division number of each line, and the speed change means changes the detected time-series printing speed to smooth and stable printing speed while satisfying inclination of the change. The second division number detection means detects a division number of each line corresponding to the printing speed after the change, and printing is performed by using the division number.

Description

  Embodiments described herein relate generally to a thermal printer that performs printing on a printing medium by energizing a number of heating elements included in the thermal head, and a control program therefor.

  A large number of heating elements are arranged in a line on the thermal head. When printing with the thermal head, the line medium is printed in the sub-scanning direction (the direction in which the heating elements are arranged) by energizing the heating elements where print dots are to be formed while conveying the print medium in the main scanning direction. Go.

  Since the printing process proceeds in this way, a large amount of driving power is required when a relatively large number of printing dots are formed in one line. If the power is insufficient, there is a problem that the heat generation amount of the heating element becomes insufficient and the print pattern becomes thin.

  Therefore, conventionally, when the printing rate of one line (number of printed dots / number of heating elements) is large, each heating element is divided into a plurality of blocks, and the heating elements belonging to each block are energized in a time-sharing manner, resulting in insufficient power. It was trying not to occur.

JP 2001-191573 A

  As described above, when energizing each heating element in a time-sharing manner, as the number of divisions increases, the time required to complete printing of one line increases as compared to the case of batch printing. In addition, the conveyance speed of the print medium must be changed.

  If it does so, in printing one printing data, the conveyance speed of a printing medium will differ for every line. Therefore, if the number of divisions of one line and the number of divisions of the next line are significantly different, the print medium cannot be smoothly conveyed, and the line is displaced from its original position, and good printing results cannot be obtained. Problems arise.

  For these reasons, it is desirable to develop a thermal printer that can stabilize the printing speed and obtain good printing results even when energizing the heating elements in a time-sharing manner to print one line. It was.

  In order to solve the above problems, a thermal printer according to an embodiment includes a thermal head in which a plurality of heating elements are arranged in a line, and the heating elements are divided into a plurality of blocks, and printing is performed according to the number of divisions. A thermal printer for printing on the print medium by driving each heating element in a time-sharing manner for each block while varying the speed, wherein the print data storage means, the print rate detection means, and the first division number detection means And a speed detection means, a speed change means, and a second division number detection means. The print data storage means stores print data. The printing rate detection unit detects a printing rate of each line of the printing data stored in the printing data storage unit. The first division number detection means detects a division number for time-dividing the driving of the heating elements when printing the lines based on the printing rate detected by the printing rate detection means. The speed detection means detects a printing speed when printing each line based on the number of divisions of each line detected by the first division number detection means. The speed changing means changes the time-series printing speed detected by the speed detecting means to a smooth and stable printing speed while satisfying the gradient of the change. The second division number detecting means detects the division number of each line corresponding to the printing speed after being changed by the speed changing means. In the thermal printer having such a configuration, printing is performed using the division number detected by the second division number detection means.

  A control program according to an embodiment includes a thermal head in which a plurality of heating elements are arranged in a line, and each heating element is divided into a plurality of blocks, and the printing speed is varied according to the number of divisions. A thermal printer control program for driving each heating element in a time-sharing manner for each block and printing on the print medium, the thermal printer having a print rate detection function, a first division number detection function, a speed A detection function, a speed change function, a second division number detection function, and a print control function are realized. The print rate detection function is a function for detecting the print rate of each line of the print data stored in the print data storage unit. The first division number detection function is a function for detecting a division number for time-dividing driving of each heating element when printing each line based on the printing rate detected by the printing rate detection function. . The speed detection function is a function of detecting a printing speed at the time of printing each line based on the number of divisions of each line detected by the first division number detection function. The speed changing function is a function for changing the time-series printing speed detected by the speed detecting function to a smooth and stable printing speed while satisfying the gradient of the change. The second division number detection function is a function of detecting the division number of each line corresponding to the printing speed after being changed by the speed changing function. The print control function is a function of performing printing on the print medium based on the number of divisions of each line detected by the second division number detection function.

FIG. 2 is a block diagram illustrating a main configuration of the thermal printer according to the first embodiment. The figure which shows the structure of the thermal head in the embodiment. The conceptual diagram for demonstrating the division | segmentation printing in the same embodiment. 6 is a timing chart showing the relationship between signals and the like during batch printing in the embodiment. 5 is a timing chart showing the relationship between signals and the like during two-division printing in the embodiment. 6 is a flowchart of processing executed by a CPU in printing processing according to the embodiment. The figure for demonstrating the print data by which the dot expansion | deployment was carried out in the same embodiment. The figure which shows the example of a data structure of the 1st division | segmentation number table in the embodiment. The figure which shows the data structure example of the 2nd division number table in the embodiment. The figure which shows an example of the 2nd division number obtained by correct | amending the 1st division number in the embodiment. The figure which shows the example of a data structure of the control system table in the embodiment. The figure for demonstrating each control system in the embodiment. The figure which shows a part of print data after rewriting in the same embodiment. The figure which shows the example of a data structure of the latch space | interval table in 2nd Embodiment. The figure for demonstrating the electricity supply pattern in the embodiment. The figure which shows the data structure example of the control system table used at the time of batch printing in the same embodiment. FIG. 4 is a diagram showing an example of the data structure of a control method table used during two-division printing in the same embodiment. FIG. 4 is a diagram showing an example of the data structure of a control method table used during three-division printing in the same embodiment.

Each embodiment will be described below with reference to the drawings.
In the following description, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

(First embodiment)
A first embodiment will be described.
FIG. 1 is a block diagram showing a main configuration of a thermal printer 1 according to this embodiment.

  The thermal printer 1 includes a CPU 10 that functions as a control center. The CPU (Central Processing Unit) 10 includes a ROM (Read Only Memory) 11, a RAM (Random Access Memory) 12, a communication interface (I / F) 13, an I / O port 14, an input control circuit 15, a display control circuit. 16, a head drive circuit 17 and a motor drive circuit 18 are connected via a bus line 19 constituted by an address bus and a data bus.

  Further, a LAN line 20 is connected to the communication interface 13, various sensors 21 are connected to the I / O port 14, an input unit 22 is connected to the input control circuit 15, a display unit 23 is connected to the display control circuit 16, A thermal head 24 is connected to the head drive circuit 17, and a transport motor 25 is connected to the motor drive circuit 18.

  The ROM 11 stores fixed data such as various control programs executed by the CPU 10 and control information. The ROM 11 also functions as a division number information storage unit and a control information storage unit in the present embodiment. The RAM 12 forms various working storage areas according to the processing scene. In particular, in print processing described later, a print data storage area is formed. That is, the RAM 12 also functions as print data storage means in the present embodiment.

  The LAN line 20 connects an external device such as a personal computer and the thermal printer 1 so that they can communicate with each other. The communication interface 13 receives data sent from the external device via the LAN line 20 and outputs the data to the CPU 10 and sends the data sent from the CPU 10 to the LAN line 20 toward the external device. .

  The various sensors 21 are, for example, a paper sensor that detects whether or not a print medium is set at a predetermined location, an edge sensor that detects the front and rear ends of the print medium, or a thermistor that detects the temperature of the thermal head 24. Etc. Output signals from these sensors are sent to the I / O port 14. The I / O port 14 transmits output signals from the various sensors 21 to the CPU 10.

  The input unit 22 includes operation buttons for various settings operated by the user, numeric keys, a touch panel, or the like. The input control circuit 15 detects an input from the input unit 22 and transmits it to the CPU 10.

  The display unit 23 includes a display such as an LCD (Liquid Crystal Display), LEDs for informing the user of various statuses of the thermal printer 1, and the like. The display control circuit 16 controls the display of the display or the like that constitutes the display unit 23 in accordance with a command from the CPU 10.

  The thermal head 24 has a large number of heating elements arranged in a line, and controls the energization timing of these heating elements to form a print pattern on a print medium. The head drive circuit 17 drives the thermal head 24 in order to print the print data stored in the RAM 12 on a print medium. Detailed configurations of the head drive circuit 17 and the thermal head 24 will be described later with reference to FIG.

  The carry motor 25 is a pulse motor whose rotation speed is variable according to the cycle of the supplied drive pulse, and carries a print medium in the main scanning direction by rotating a carry roller (not shown). The motor drive circuit 18 adjusts the period of the drive pulse supplied to the carry motor 25 and rotates the carry motor 25 at an arbitrary speed.

[Thermal head]
As shown in FIG. 2, the thermal head 24 includes a latch circuit 30, an energization control circuit 31, and an edge head 32. The edge head 32 has a large number of heat transfer elements 321, 322, 323,... 32n for thermal transfer arranged in a line. The latch circuit 30 latches print data (DIN) supplied from the head drive circuit 17 for each line in accordance with a latch pulse (Latch) supplied from the head drive circuit 17. The energization control circuit 31 energizes each heating element 321 to 32n of the edge head 32 according to the data latched by the latch circuit 30, and the timing when the strobe signal (STB) supplied from the head drive circuit 17 is turned on. Control it.

[Split printing]
The thermal printer 1 in the present embodiment forms one print dot on the print medium by energizing the corresponding one of the heat generating elements 321 to 32n four times. Furthermore, when printing one line, each heating element 321-32n is divided into a plurality of blocks, and the printing speed is varied according to the number of divisions, and each heating element 321-32n is time-divided for each block. It is equipped with a function to drive and print on a print medium. In the present embodiment, it is assumed that printing is performed in one of division (that is, batch), two divisions, and three divisions. However, this does not preclude the adoption of other division modes such as the introduction of the number of divisions of four or more divisions.

  FIG. 3 is a conceptual diagram for explaining one-line divided printing. As described above, one printing dot is formed by energizing one heating element four times. Therefore, in the case of batch printing, there are four timings T1, T2, T3, and T4 for energizing the heat generating elements 321 to 32n when printing one line.

  In the case of two-division printing, each of the heat generating elements 321 to 32n is divided into two equal parts, block A and block B. The heating elements belonging to the block A are energized at four timings Ta1, Ta2, Ta3, and Ta4, and the heating elements belonging to the block B are energized at four timings Tb1, Tb2, Tb3, and Tb4.

  In the case of three-division printing, each of the heat generating elements 321 to 32n is divided into three equal parts, block C, block D, and block E. The heating elements belonging to the block C are energized at four timings Tc1, Tc2, Tc3, Tc4, and the heating elements belonging to the block D are energized at four timings Td1, Td2, Td3, Td4, The heating elements belonging to the block E are energized at four timings Te1, Te2, Te3, and Te4.

  In this embodiment, the time width (latch interval) at which the latch circuit 30 latches data at each of the energization timings T1 to T4, Ta1 to Ta4, Tb1 to Tb4, Tc1 to Tc4, Td1 to Td4, and Te1 to Te4, It is assumed that all are t (msec).

  FIG. 4 is a timing chart showing the relationship between the latch pulse (Latch), strobe signal (STB), operation clock (CLK), and next transfer data (DIN) waiting for transfer to the latch circuit 30 in batch printing. ing. The next transfer data (DIN) means latch-waiting data held by a shift register (not shown) provided in the thermal head 24 or the head drive circuit 17, for example.

  When the strobe signal (STB) switches from the low level (on) to the high level (off), the supply of the latch pulse (Latch) is instantaneously stopped and then restarted, and the next transfer data (DIN) corresponding to the timing T1 Is latched by the latch circuit 30. Immediately thereafter, the strobe signal (STB) is switched to the low level (ON), the energization control circuit 31 energizes the one corresponding to the latched data among the heat generating elements 321-32n, and the next transfer data (DIN) is The data corresponds to the timing T2. When the latch interval t elapses after the data corresponding to the timing T1 is latched, the supply of the latch pulse (Latch) is instantaneously stopped and then restarted, and the next transfer data (DIN) corresponding to the timing T2 is latched. 30 is latched. At this time, since the strobe signal (STB) is continuously at the low level (ON), the energization control circuit 31 energizes one of the heating elements 321 to 32n corresponding to the latched data, and the next transfer data ( DIN) is data corresponding to the timing T3. Similarly, the data corresponding to the timings T3 and T4 are latched in the latch circuit 30, and the energization control circuit 31 energizes the heater elements 321 to 32n corresponding to the latched data. When the strobe signal (STB) is switched to the high level (off) again, the energization control circuit 31 stops energizing the heating elements 321-32n, and the same processing is repeated for the next line.

  In such a configuration, the printing cycle of one line coincides with the time until the strobe signal (STB) switches from the high level to the low level and then switches from the high level to the low level again. That is, in this embodiment, since the latch intervals of the respective energization timings T1 to T4 are all t, the printing cycle for one line is about 4t.

  FIG. 5 is a timing chart showing the relationship between the latch pulse (Latch), strobe signal (STB), operation clock (CLK), and next transfer data (DIN) waiting for transfer to the latch circuit 30 in the case of two-division printing. Show. As shown in the drawing, in the case of two-division printing, data latching and energization to the heating elements are performed in the order of timings Ta1, Tb1, Ta2, Tb2, Ta3, Tb3, Ta4, and Tb4. That is, when printing one line, the heating elements belonging to the block A and the heating elements belonging to the block B are alternately energized four times each. In this case, since the latch intervals of the timings Ta1 to Ta4 and Tb1 to Tb4 are all t, the printing cycle of one printing line is about twice 8t compared to the case of batch printing.

  Although not shown, in the case of three-division printing, data latch and heat generation in the order of timings Tc1, Td1, Te1, Tc2, Td2, Te2, Tc3, Td3, Te3, Tc4, Td4, and Te4. The element is energized. That is, when printing one line, the heating elements belonging to the block C, the heating elements belonging to the block D, and the heating elements belonging to the block E are energized four times in this order. In this case, since the latch intervals of the timings Tc1 to Tc4, Td1 to Td4, and Te1 to Te4 are all t, the printing cycle of one printing line is about 3 times that of the batch printing, which is about 12 times.

[Print processing]
The printing process by the thermal printer 1 will be described.
FIG. 6 is a flowchart of processing executed by the CPU 10 in the printing processing. This process is realized by the CPU 10 executing the operation program stored in the ROM 11.

  At the beginning of this process, the CPU 10 waits for reception of print data from the host device (step S1). When the communication interface 13 receives print data from the host device via the LAN line 20 (Yes in step S1), the CPU 10 stores the received print data in the RAM 12.

  Next, the CPU 10 performs dot development on the print data stored in the RAM 12 and detects the print rates R1, R2, R3,... Rm (m: total number of lines) of each line (step S2: print rate detecting means). Specifically, first, data as shown in FIG. 7 is created by dot development. In this data, printing dots (“1”) and non-printing dots (“0”) are arranged in a matrix of n heating elements × m lines. Then, the printing ratios R1 to Rm are calculated by dividing the number of printing dots of each line in the data by the number n of heating elements.

  When detecting the respective printing ratios R1 to Rm, the CPU 10 detects the division numbers D1, D2, D3,... Dm of each line (step S3: first division number detection means). In this process, the first division number table 40 (first division number information) stored in the ROM 11 is used. FIG. 8 shows an example of the data structure of the first division number table 40. In this table 40, when the printing rate R is less than the threshold value Rs1 (R <Rs1), the number of divisions is 1 (that is, batch), and the printing rate R is greater than or equal to the threshold value Rs1 and less than the threshold value Rs2 (Rs1 ≦ R <Rs2). In some cases, the number of divisions is 2, and when the printing rate R is equal to or greater than the threshold value Rs2 (Rs2 ≦ R), the number of divisions is 3. Note that the threshold value Rs1 indicates the minimum value of the printing rate that requires power that can degrade print quality when batch printing is performed, and the threshold value Rs2 indicates printing that requires power that can degrade print quality even when divided printing is performed. The lowest rate is shown. Specific values of the threshold values Rs1 and Rs2 may be determined theoretically or empirically. From the relationship between the printing rate R and the number of divisions defined by the first division number table 40 having such a data structure, the CPU 10 determines the division numbers D1 to Dm for each line. Hereinafter, the division number determined in the process of step S3 is referred to as a first division number.

  When the first division numbers D1 to Dm for each line are determined, the CPU 10 determines the printing speeds V1, V2, V3,... Vm for printing each line based on the determined first division numbers D1 to Dm for each line. It detects (step S4: speed detection means). Specifically, the printing speeds V1 to Vm are calculated using the first division numbers D1 to Dm and a predetermined calculation formula. As described above, when printing one line, energization is performed at the timing of 4 times in the case of batch printing, energization is performed at the timing of 8 times in the case of 2-division printing, and 12 times in the case of 3-division printing. And the latch time at each timing is t. Furthermore, since the distance that the print medium should be conveyed during printing one line is constant, the print speeds V1 to Vm can be calculated by using the first division numbers D1 to Dm. Instead of detecting the printing speeds V1 to Vm by such calculation, the printing speeds V1 to Vm may be detected using a table in which the printing speed is associated with each division number.

  When the printing speeds V1 to Vm of each line are detected, the CPU 10 changes the time-series printing speeds V1 to Vm to smooth and stable printing speeds V1 ′ to Vm ′ while satisfying the inclination of the change (step S5). : Speed change means). Here, for example, the printing speeds V1 to Vm ′ are obtained by smoothing the printing speeds V1 to Vm by taking a moving average or a weighted moving average using the printing speed of each line and the printing speeds of several lines before and after that. . In addition, various methods are used to stabilize smoothly while satisfying the gradient of changes in the printing speeds V1 to Vm, such as using a table in which correction values of printing speeds are associated with combinations of printing speeds of several lines before and after. Can do.

  When the printing speeds V1 to Vm of each line are smoothed, the CPU 10 detects the division numbers D1 ′ to Dm ′ corresponding to the printing speeds V1 ′ to Vm ′ after the smoothing (step S6: second division number detection means). ). In this process, the second division number table 41 (second division number information) stored in the ROM 11 is used. FIG. 9 shows a data structure example of the second division number table 41. In this table 41, when the printing speed V ′ after smoothing is less than the threshold value Vs1 (V ′ <Vs1), the number of divisions is set to 1 (ie, batch), and the printing speed V ′ after smoothing is equal to or higher than the threshold value Vs1. The division number should be 2 when it is less than the threshold Vs2 (Vs1 ≦ V ′ <Vs2), and the division number should be 3 when the printing speed V ′ after smoothing is equal to or higher than the threshold Vs2 (Vs2 ≦ V ′). It is shown that. The threshold values Vs1 and Vs2 define ranges in which the printing speed V ′ can be regarded as the same as the printing speed at the time of batch printing, two-division printing, and three-division printing. The specific value may be determined theoretically or empirically. Hereinafter, the number of divisions determined in step S6 is referred to as a second number of divisions.

  An example of the second division numbers D1 ′ to Dm ′ obtained based on the first division numbers D1 to Dm is shown in FIG. This figure is a graph in which the horizontal axis is the line number (1 to m) of each line and the vertical axis is the number of divisions. The solid line in the figure indicates the first division number, and the broken line indicates the second division number obtained by correcting the first division number. In this example, the first division numbers D1 to Dm increase toward the second line, decrease at the third line, increase at the fourth line, decrease at the fifth line, increase at the sixth and seventh lines, and at the eighth line. The increase and decrease are repeated like decrease. In this case, the printing speeds V1 to Vm calculated in step S4 are also repeatedly increased and decreased. However, the printing speed is smoothed by the process of step S5, and the second division numbers D1 ′ to Dm ′ calculated based on the printing speeds V1 ′ to Vm ′ after the smoothing by the process of step S6 are the first The same number of divisions is maintained from the line to the fifth line, and the number of divisions increases in the sixth line, but the same number of divisions is maintained in the seventh and eighth lines. In this way, the number of increases / decreases in the second division numbers D1 ′ to Dm ′ is less than that in the first division numbers D1 to Dm. In other words, the degree of smoothing of the printing speeds V1 to Vm in the process of step S5 is determined so that the increase / decrease in the first division numbers D1 to Dm is alleviated, and the second division number table used in the process of step S6. The threshold values Vs1 and Vs2 in 41 may be determined.

  When the second division numbers D1 ′ to Dm ′ for each line are determined, the CPU 10 determines the strobe times S1, S2, S3,... Sm (strobes) for each line based on the second division numbers D1 ′ to Dm ′ for each line. The interval for turning on the signal is determined (step S7). As described above, when printing one line, energization is performed at the timing of 4 times in the case of batch printing, energization is performed at the timing of 8 times in the case of 2-division printing, and 12 is performed in the case of 3-division printing. Since the energization is performed at the number of times and the latch time at each timing is t, the printing period of each line is determined by using the second division numbers D1 ′ to Dm ′, and the strobe times S1 to Sm are determined.

  Usually, the higher the printing speed, the more the residual heat at the time of printing the previous line affects the printing of the next line. In view of this, in the present embodiment, the print data of the next line is rewritten in consideration of the residual heat. Hereinafter, the rewriting method is referred to as a print control method.

  After determining the strobe times S1 to Sm, the CPU 10 determines the print control method for each line based on the second division numbers D1 ′ to Dm ′ (step S8). In this process, the control method table 42 (drive control information) stored in the ROM 11 is used. FIG. 11 shows an example of the data structure of the control method table 42. In this table 42, the print control method is X1 when the second division number is 1 (that is, batch), the print control method is X2 when the second division number is 2, and the second division number is 3. This indicates that the stamp control method should be X3 in some cases.

  Each control method will be described with reference to FIG. In the control method X1, the first two of the four energization timings of the energization location (“1” location) in the print data as shown in FIG. 7 are set to “0” (no energization), and the rest are set to “1”. This is a method of “with energization”. The control method X2 is a method in which the first one among the four energization timings at the energization location is set to “0” and the rest is set to “1”. The control method X3 is a method in which all four energization timings at the energization location are set to “1”. Thus, the smaller the second number of divisions, the smaller the number of energizations for forming one print dot.

  If the print control method for each line is determined in the process of step S8, the CPU 10 rewrites the print data based on the print control method for each line (step S9). Specifically, the print data for one line is divided into four energization timings, and the distinction between “0” and “1” of the print data at each energization timing is rewritten based on the print control method for the same line. Then, as shown in FIG. 13, in the batch printing line, all the data corresponding to the energization timings T1 and T2 become “0”, and the data corresponding to the energization timings T3 and T4 is equivalent to the original print data. Become. In the two-divided printing line, all the data corresponding to the energization timings Ta1 and Tb1 are “0”, and the data corresponding to the energization timings Ta2, Tb2, Ta3, Tb3, Ta4, and Tb4 are the original prints. Equivalent to data. In the three-divided printing line, the data corresponding to the energization timings Tc1, Td1, Te1, Tc2, Td2, Te2, Tc3, Td3, Te3, and Tc4, Td4, Te4 are all equivalent to the original print data. Become.

  When the print data is rewritten in this way, the CPU 10 outputs the rewritten print data, the latch interval (t in this embodiment), and the strobe times S1 to Sm to the head drive circuit 17 to start the print operation ( Step S10). When the chopper control for further time-sharing the energization time width determined by the strobe signal (STB) is performed in the printing operation, a control signal indicating that the same control is performed together with the print data and the strobe times S1 to Sm. Is output.

  When the print data, the latch interval, and the strobe times S1 to Sm are received, the head driving circuit 17 stores the received print data in a print buffer (not shown). Further, when printing each line, the motor driving circuit 18 drives the transport motor 25 so that the print medium is transported in the line width of each line in the same time as the strobe time of each line. Then, while supplying a latch pulse (Latch) of the latch interval t to the latch circuit 30, the print data stored in the print buffer is supplied as the next print data (DIN) in order from the first line, and the strobe time is further supplied to the energization control circuit 31. The strobe signals (STB) of S1 to Sm are sequentially supplied, and the printing operation proceeds. When the control signal for performing the chopper control is received, the strobe signal supplied at the time of printing each line is further time-divided.

  When the printing operation proceeding in this way is completed, the CPU 10 returns to the process of step S1 and waits for the reception of the next print data.

  As described above, the thermal printer 1 according to the present embodiment detects the first division numbers D1 to Dm based on the printing rates R1 to Rm of each line, and further detects each line based on the first division numbers D1 to Dm. The printing speeds V1 to Vm are detected, the printing speeds V1 to Vm are smoothed to obtain the printing speeds V1 ′ to Vm ′, and the second division numbers D1 ′ to Dm ′ corresponding to the printing speeds V1 ′ to Vm ′ are detected. The printing operation is performed using the second division numbers D1 ′ to Dm ′. By doing in this way, the rapid change of the printing speed which may arise when printing each line is eliminated. Therefore, the printing speed can be switched smoothly when each line is printed, and a good printing result can be obtained.

  Further, the thermal printer 1 according to the present embodiment is configured to reduce the number of times each of the heating elements 321 to 32n is driven as the second division number of the line is smaller when printing one line on the print medium. Yes. By doing in this way, generation | occurrence | production of the printing nonuniformity by the residual heat of each heat generating element 321-32n at the time of front line printing can be suppressed, and a more favorable printing result can be obtained. Furthermore, it is possible to reduce power consumption when printing a line with a small number of divisions.

(Second Embodiment)
Next, a second embodiment will be described.
In this embodiment, in the process of step S8 in the flowchart shown in FIG. 6, the print control method is determined by referring to the print data of the previous line and the previous line, and the latch interval is changed depending on the number of divisions. Thus, it is different from the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The latch interval for each division number is determined by a latch interval table 43 stored in the ROM 11. FIG. 14 is a schematic diagram illustrating a data structure example of the latch interval table 43. In the illustrated table 43, four energization timings for forming one printing dot are t11, t12, t13, and t14, respectively, in the case of batch, and t21, t22, t23, and t24 in the case of two divisions, respectively. In the case of three divisions, t31, t32, t33, and t34 are to be indicated, respectively.

  In the processing of step S4 and step S7 of the flowchart shown in FIG. 6, the CPU 10 detects the printing speeds V1 to Vm and the strobe times S1 to Sm of each line using the latch interval table 43. That is, the sum of t11, t12, t13, and t14 is calculated in the case of batch printing, and the sum of t21, t22, t23, and t24 is calculated in the case of two-split printing, and the sum of three-split printing is calculated. In this case, a value obtained by multiplying the sum of t31, t32, t33, and t34 by three is calculated, and the printing speeds V1 to Vm and the strobe times S1 to Sm are calculated based on these values.

  Next, the print control method will be described. In the present embodiment, the print control method is determined for each print dot (for each heating element), not for each line. At that time, the number of divisions of the line to which the print dot belongs and the presence / absence of energization at the time of printing the previous line and the previous line to the heating element corresponding to the dot are considered.

  As shown in FIG. 15, the presence / absence of energization at the time of printing the previous line and the previous line is divided into four patterns of a first pattern, a second pattern, a third pattern, and a fourth pattern. The first pattern is a case where the target heating element is not energized at the time of printing the previous line and the previous line, and the second pattern is not energized at the time of printing the previous line, but at the time of printing the previous line The third pattern is a case where the same heating element is energized at the time of printing the previous line, but is not energized at the time of printing the previous line, and the fourth pattern is the case where the same heating element is previously turned on. This is a case where power is supplied during printing of the line and the previous line.

  The ROM 11 has a control method table 51 that defines a print control method to be set for the first to fourth patterns in the case of batch printing, and is set for the first to fourth patterns in the case of two-division printing. A control method table 52 that defines the print control method to be controlled and a control method table 53 that defines the print control method to be set for the first to fourth patterns in the case of three-division printing are stored.

  FIG. 16 shows a data structure example of the control method table 51. In this table 51, for printing dots belonging to a batch printing line, the control method is X11 for the first pattern, the control method is X12 for the second pattern, and the control method is X13 for the third pattern. This indicates that the control method should be X14 in the case of the fourth pattern.

  FIG. 17 shows a data structure example of the control method table 52. In this table 52, for the printing dots belonging to the two-division printing line, the control method is X21 for the first pattern, the control method is X22 for the second pattern, and the control method is X23 for the third pattern. This indicates that the control method should be X24 in the case of the fourth pattern.

  FIG. 18 shows a data structure example of the control method table 53. In this table 53, for the printing dots belonging to the three-division printing line, the control method is X31 for the first pattern, the control method is X32 for the second pattern, and the control method is X33 for the third pattern. This indicates that the control method should be X34 in the case of the fourth pattern.

  Each of the control methods X11 to X14, X21 to X24, and X31 to X34 takes into account the influence of the residual heat of the heating element at the time of printing the previous line and the previous line, and at the four energization timings for forming one print dot. The energization permission / denial of the heating element is varied.

  From this point of view, in the present embodiment, the four energization timings in the case of batch printing are all set to “1” in the control method X11, and the first two energization timings in the control method X12 in consideration of the remaining heat at the time of previous line printing. Is set to “0”, the remaining is set to “1”, and in the control method X13, the first energization timing is set to “0” and the remaining is set to “1” in consideration of the remaining heat at the time of line printing, and the remaining control method X14. The first three energization timings are set to “0” and the rest are set to “1” in consideration of the remaining heat at the time of the previous line and the previous line printing.

  In the case of two-division printing, the printing speed is slower than in the case of batch printing, so that it is less likely to be affected by the residual heat at the time of the previous line and previous line printing. Therefore, the control methods X21, X22, and X23 have the same control mode as the control methods X11, X12, and X13, respectively, but the control method X24 sets the third energization timing that is “0” in the control method X14 to “1”. Increasing the number of energizations.

  In the case of three-division printing, the printing speed is further slowed down, so that it is less susceptible to the influence of the remaining heat at the time of the previous line and the previous line printing than in the case of two-division printing. Therefore, although the control methods X31 and X34 have the same control mode as the control methods X21 and X24, respectively, the control method X32 sets the second energization timing which is “0” in the control method X22 to “1”, and the control method X33. In the control method X23, the first energization timing which is “0” is set to “1” to increase the number of energizations.

  In the process of step S8 in the flowchart shown in FIG. 6, the CPU 10 determines which of the first to fourth patterns belongs to each print dot of the print data as shown in FIG. The print control method is determined with reference to the second division numbers D1 ′ to Dm ′ of the line to which the print dot belongs. In the process of step S9, one line of print data is divided into four energization timings, and each of the print dots at each energization timing is distinguished from “0” and “1” based on the print control method for each print dot. I will rewrite it.

  In the process of step S 10, the CPU 10 outputs the print data rewritten as described above, the latch interval data in which the latch intervals for each energization timing are arranged, and the strobe times S 1 to Sm to the head drive circuit 17. The latch interval data is configured, for example, by arranging data corresponding to each line among the latch times t11 to t14, t21 to t24, and t31 to t34 in order from the first line of the rewritten print data.

  When the print data, the latch interval data, and the strobe times S1 to Sm are received, the head drive circuit 17 stores the received print data in a print buffer (not shown). Further, when printing each line, the motor driving circuit 18 drives the transport motor 25 so that the print medium is transported in the line width of each line in the same time as the strobe time of each line. Then, a latch pulse (Latch) of the latch interval indicated by the latch interval data is supplied to the latch circuit 30 in order from the one corresponding to the first line, while the print data stored in the print buffer is sequentially supplied from the first line to the next print data ( DIN) and a strobe signal (STB) of strobe times S1 to Sm are sequentially supplied to the energization control circuit 31 to advance the printing operation. When the control signal for performing the chopper control is received, the strobe signal supplied at the time of printing each line is further time-divided.

  As described above, when the thermal printer 1 according to the present embodiment prints one line on the printing medium, the thermal element 321 to 32n that is driven at the time of printing the previous line and the previous line of the heat generating elements 321 to 32n is driven. It is configured to reduce the number of times. By doing in this way, each line can be printed by using the remaining heat at the time of the previous line and the previous line printing more appropriately.

  In addition, by appropriately changing the latch times t11 to t14, t21 to t24, t31 to t34 determined by the latch interval table 43, and the contents of the control method determined by the control method tables 51 to 53, the thermal printer 1 The optimum setting desired by the user can be realized.

(Modification)
Note that the configuration disclosed in each of the embodiments can be embodied by appropriately modifying each component in the implementation stage. Specific examples of modifications are as follows.

(1) In the above embodiments, the second division numbers D1 to Dm are detected based on the printing speeds V1 to Vm of the respective lines. However, the second division numbers D1 to Dm may be detected not using the printing speed itself but using a parameter having the same meaning as the printing speed. As an example, a method using a printing cycle can be adopted. That is, the second division number table 41 is changed to one in which the division number corresponds to the printing cycle, and in the process of step S4, the printing cycle of each line is detected based on the first division number D1 to Dm. In the processing, the detected printing cycle is smoothed, and in the processing of step S6, the second division number corresponding to the smoothed printing cycle is detected from the second division number table 41. Thus, even when a series of processing is realized using a printing cycle that is a parameter synonymous with printing speed, the same effects as those of the above-described embodiments can be obtained.

(2) In each of the above embodiments, printing is performed by any one of batch printing, two-division printing, and three-division printing. However, division modes of four or more divisions may be added, and printing may be performed in two division modes, such as batch printing and two divisions, or batch printing and three divisions. When changing the division mode, the configuration of each table or the like may be changed as appropriate.
Further, in the case of two-division printing, the heating elements 321 to 32n are not divided into two at the center of the arrangement order, but the odd-numbered heating elements 321, 323, 325. The elements 322, 324, 326... May be the block B. Similarly, in the case of three-division printing, the heating elements belonging to the blocks C, D, and E may be alternately arranged from one end.

(3) In the second embodiment, it is assumed that the print control method for each heating element is determined by looking at the energization state of the previous line and the previous line. However, the print control method may be determined in consideration of the energization status of more lines, such as by checking the energization status of the previous three lines. It may be determined.

  In addition, some constituent elements may be deleted from all the constituent elements shown in the respective embodiments, or constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 1 ... Thermal printer, 10 ... CPU, 11 ... ROM, 12 ... RAM, 17 ... Head drive circuit, 18 ... Motor drive circuit, 24 ... Thermal head, 25 ... Conveyance motor, 30 ... Latch circuit, 31 ... Current supply control circuit, 32 ... Edge head, 40 ... First division number table, 41 ... Second division number table, 43 ... Latch interval table, 42, 51 to 53 ... Control method table

Claims (6)

A thermal head having a plurality of heating elements arranged in a line is formed, and each heating element is divided into a plurality of blocks, and the printing speed is varied according to the number of divisions, and the heating elements are arranged for each block. A thermal printer that prints on a print medium by driving in divisions,
Print data storage means for storing print data;
A print rate detecting means for detecting a print rate of each line of the print data stored in the print data storage means;
First division number detection means for detecting a division number for time-dividing driving of each heating element when printing each line based on the printing rate detected by the printing rate detection means;
Speed detecting means for detecting a printing speed when printing each line based on the number of divisions of each line detected by the first division number detecting means;
A speed changing means for changing the time-series printing speed detected by the speed detecting means to a smooth and stable printing speed while satisfying the gradient of the change;
Second division number detecting means for detecting the division number of each line corresponding to the printing speed after being changed by the speed changing means;
And performing printing using the number of divisions detected by the second division number detecting means. When the same line is printed with respect to the printing rate of one line, the first division number information that defines the number of divisions for time-dividing the driving of each heating element, and the same line is printed at the printing speed of one line. A division number information storage means for storing second division number information that defines the number of divisions for time division of driving of each of the heating elements.
The first division number detection means detects a division number for time-dividing the driving of the heating elements when printing the lines based on the first division number information, and the second division number detection means 2. The thermal printer according to claim 1, wherein the number of divisions for time-dividing the driving of the heating elements is detected when the lines are printed based on the second division number information. The thermal head forms one print dot on the print medium by driving the heating element a plurality of times,
3. The thermal printer according to claim 1, wherein, when printing one line on the print medium, the number of times the heating element is driven is reduced as the second division number of the line is smaller. The thermal head forms one print dot on the print medium by driving the heating element a plurality of times,
3. The thermal printer according to claim 1, wherein when one line is printed on the print medium, the number of times of driving of the heat generating element driven when printing a line immediately before the line or a plurality of lines immediately before the line is reduced. . Control information storage means for storing drive control information that defines the number of times the heating element is driven with respect to the combination of the presence or absence of driving of the heating element at the time of printing a plurality of lines immediately before,
5. The number of times of driving the heating element driven when printing a plurality of lines immediately before the line is reduced when printing one line on the print medium according to the drive control information. Thermal printer. A thermal head having a plurality of heating elements arranged in a line is formed, and each heating element is divided into a plurality of blocks, and the printing speed is varied according to the number of divisions, and the heating elements are arranged for each block. A control program for a thermal printer that is driven by division and prints on a print medium,
In the thermal printer,
A print rate detection function for detecting the print rate of each line of the print data stored in the print data storage unit;
A first division number detection function for detecting a division number for time-dividing the driving of each heating element when printing each line based on the printing rate detected by the printing rate detection function;
A speed detection function for detecting a printing speed when printing each line based on the number of divisions of each line detected by the first division number detection function;
A speed changing function for changing the time-series printing speed detected by the speed detecting function to a smooth and stable printing speed while satisfying the gradient of the change;
A second division number detection function for detecting the division number of each line corresponding to the printing speed after being changed by the speed change function;
A print control function for performing printing on the print medium based on the division number of each line detected by the second division number detection function;
Control program to realize.

Images