JP2011255632A - Recording head control method and dot impact printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording head control method of in which drop in print throughput can be suppressed while preventing a head coil from burning due to heating.SOLUTION: In the control method for a recording head 18 in a dot impact printer 100 where information is printed on a recording medium S by driving a recording wire 9 while scanning a carriage 19 mounting a recording head 10 having a plurality of recording wires 9, each recording wire 9 takes charge of printing of 1 dot line in the scanning direction of the carriage 19. When the dot line is printed, a determination is made whether or not reference number N (N is 2 or more) or more of preset specific dot patterns P1 and P2 are included in a dot line to be printed before printing is performed, and drive mode of the recording head 18 for printing the dot line is determined based on the result of determination.

Description

  The present invention relates to a recording head control method for recording information by driving a recording wire to form dots on recording paper, and a dot impact printer including the recording head.

  Dot impact printers are used in various fields mainly for high reliability and overprinting on copy paper. The dot impact printer includes a recording head having a plurality of recording wires (wire pins). The recording head has an electromagnet coil (head coil) for driving the recording wire for each recording wire, and the recording wire is selectively protruded by selectively driving the electromagnet coil. A dot impact printer has a recording head mounted on a carriage, and while the carriage is scanned in the paper width direction of the recording paper, the recording wire of the recording head is selectively struck onto the recording paper via an ink ribbon, and dots are formed on the recording paper. Form and record information.

  In the dot impact printer, when the recording wire is driven continuously or frequently, the temperature of the head coil (electromagnetic coil) driving the recording wire rapidly increases. And when remarkable, there exists a possibility of burning out. Therefore, in order to prevent problems such as burning of the head coil, the temperature of the recording head is detected by a temperature detector such as a thermistor, and the amount of heat generated by the head coil is reduced when the temperature becomes a risk of burning. Control is in progress. For example, when the temperature of the recording head reaches a preset speed-down temperature, the print speed is reduced by reducing the drive frequency of the head coil. Further, when the temperature of the recording head reaches a preset stop set temperature, the printing operation by the recording head is stopped at that time. A dot impact printer that controls the head coil so as not to reach the burnout limit temperature is known (for example, see Patent Document 1).

JP 2003-127441 A

  However, when the temperature of the head coil suddenly rises, the head coil detects that the head coil has reached a preset temperature by the temperature detector and executes processing such as deceleration and stop. The burnout limit temperature may be exceeded and burnout may not be prevented. For this reason, in order to prevent such a situation, the dot impact printer described above sets in advance a specific dot pattern (specific recording pattern) that is predicted to cause a rapid temperature increase. When this specific recording pattern is detected in the print data, the printing operation is performed with the speed-down set temperature and stop set temperature set lower than normal. As a result, even when the temperature of the head coil suddenly increases, the printing operation can be decelerated or stopped before the head coil reaches the burnout limit temperature.

  The dot impact printer described above changes the speed-down set temperature and the stop set temperature to a low temperature when a specific recording pattern is detected even at one location. Therefore, for example, printing of a specific recording pattern is performed in a state where the temperature of the recording head is sufficiently low, and even if the specific recording pattern is printed and the burnout limit temperature is not reached, the printing speed is reduced or printing is performed. The operation may be stopped. That is, the above-described dot impact printer has a problem that the printing throughput may be reduced because there is a possibility that the deceleration or the stop is performed even when the deceleration or the stop is not necessary.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  (Application Example 1) A method of controlling a recording head in a dot impact printer that prints information on a recording medium by driving the recording wire while scanning a carriage on which a recording head having a plurality of recording wires is mounted. Each of the recording wires is in charge of printing one dot line in the carriage scanning direction. In the printing of the dot line, a specific dot set in advance on the dot line to be printed before printing is performed. It is determined whether or not a pattern includes a reference number of 2 or more, and based on the determination result, a driving mode of the recording head for printing the dot line is determined. Control method.

  According to this method, it is possible to set a specific dot pattern that may cause a rapid temperature increase of the recording head. Then, it is possible to determine whether or not a specific dot pattern is included in the dot line to be printed by a reference number or more, and the drive mode can be selected. That is, it is determined whether or not there is a possibility that an abrupt temperature increase of the recording head may occur in the dot line or more, and the temperature of the recording head is set to the burnout limit temperature of the head coil in the printing of the dot line. It can be determined whether or not there is a risk of exceeding. Therefore, if it is determined that there is a risk of exceeding the burnout limit temperature of the head coil, printing can be executed in a drive mode set so as not to cause burnout. On the other hand, if it is determined that there is no risk of exceeding the burnout limit temperature of the head coil, printing can be executed without changing the drive mode. As a result, it is possible to suppress the deterioration of the printing throughput more than necessary while reliably preventing burning of the head coil.

  (Application Example 2) A plurality of pattern detection areas having a predetermined width are set in advance in the area of the maximum line length of the dot lines, and in the printing of the dot lines, before the printing is performed, the dot lines to be printed Determining whether the pattern detection area is a specific area including the specific dot pattern, determining whether the number of the specific areas in the dot line is greater than or equal to the reference number, and determining them The recording head control method according to claim 1, wherein a driving mode of the recording head for printing the dot lines is determined based on a result.

  According to this method, it may be determined whether or not a specific dot pattern is included in a pattern detection region having a predetermined width, and the number of specific regions included may be determined. Therefore, the processing load can be reduced compared to the case where the entire dot line data is compared with a specific dot pattern.

  (Application Example 3) As the drive mode of the recording head, a plurality of drive modes having different calorific values are set in advance, and the drive mode and the temperature of the print head are associated with each other. The temperature of the recording head associated with the drive mode includes at least two temperatures of a first temperature and a second temperature lower than the first temperature. When the temperature of the recording head is detected and the number of the specific areas in the dot line to be printed is equal to or larger than the reference number, the second temperature is used to correspond to the detected temperature of the recording head. And when the number of the specific areas in the dot line to be printed is less than the reference number, the detected temperature is detected using the first temperature. Selecting the driving mode corresponding to the temperature of the head, by selected the drive mode, the control method of the recording head and executes the printing of the dot line.

  According to this method, a plurality of print head temperatures associated with a plurality of drive modes can be set. Therefore, it is possible to select a driving mode by using two or more types of temperatures based on the number of pattern detection areas including a specific dot pattern. As a result, it is possible to suppress the deterioration of the printing throughput more than necessary while reliably preventing burning of the head coil.

  Application Example 4 When the temperature of the recording head detected before printing is equal to or lower than a preset reference temperature, the determination result as to whether the pattern detection area is the specific area is not used. The method for controlling a recording head as described above, wherein the driving mode of the recording head is determined.

  According to this method, it is possible to know that there is a possibility that the burnout limit temperature of the head coil may not be exceeded even though a specific dot pattern is printed in a plurality of pattern detection areas, thereby reducing the print throughput. Can be suppressed.

  (Application example 5) The print quality of print data and the drive mode of the recording head are associated with each other, and in the printing of the dot line, the print quality is associated with the print quality of the print data including the dot line to be printed. The printing head control method described above, wherein the printing of the dot lines is executed in accordance with the driving mode determined from the driving modes.

  The dot impact printer has different recording head drive control depending on the print quality setting. Therefore, the degree of temperature rise differs depending on the print quality. According to this method, it is possible to set the drive mode in association with the print quality. For this reason, it is possible to achieve both prevention of burning of the head coil and suppression of reduction in printing throughput.

  (Application Example 6) The recording described above, wherein the specific dot pattern is set based on the number of the recording wires that are simultaneously driven during printing and the number of continuous driving times of the same recording wire. Head control method.

  In a dot impact printer, as the number of recording wires that are driven simultaneously increases and the number of times of continuous driving increases, that is, as the dot density increases, the temperature rises more rapidly. According to this method, it is possible to set a specific dot pattern that is assumed to cause a rapid temperature increase based on these parameters.

  Application Example 7 A recording having a carriage that is scanned in a direction substantially orthogonal to a feeding direction of a recording medium on which information is printed, and a plurality of recording wires that are mounted on the carriage and form a print dot row in a dot line A head and a control unit that controls the recording head, wherein the control unit determines a driving mode of the recording head and executes the printing of the dot lines by the control method of the recording head. A dot impact printer characterized by

  According to this configuration, the dot impact printer can set a specific dot pattern that can cause a rapid temperature rise of the recording head. Then, it is possible to determine whether or not a specific dot pattern is included in the dot line to be printed by a reference number or more, and the drive mode can be selected. That is, it is determined whether or not a rapid temperature rise of the recording head occurs in the dot line or more, and the temperature of the recording head may exceed the burnout limit temperature of the head coil in the printing of the dot line. It can be determined whether or not. Therefore, if it is determined that there is a risk of exceeding the burnout limit temperature of the head coil, printing can be executed in a drive mode set so as not to cause burnout. On the other hand, if it is determined that there is no risk of exceeding the burnout limit temperature of the head coil, printing can be executed without changing the drive mode. As a result, it is possible to provide a dot impact printer that can prevent the head coil from being burned out reliably and suppress a decrease in printing throughput more than necessary.

The perspective view which shows the printer main body of a dot impact printer. FIG. 3 is a side sectional view of a printer body of a dot impact printer. FIG. 3 is a cross-sectional view of a recording head. FIG. 3 is an exploded perspective view of a recording head. FIG. 3 is a block diagram showing a printing control system in a dot impact printer. FIG. 6 is a layout diagram of pattern detection areas in each dot line. Explanatory drawing of the special bit image (specific dot pattern) used for determination of a drive mode. A control table for determining the drive mode. 6 is a flowchart showing a flow of printing processing of each dot line using a control table.

  Hereinafter, the present embodiment will be described with reference to the drawings. In the drawings referred to in the following description, the vertical and horizontal scales of members or parts may be shown differently from the actual ones for convenience of description and illustration.

(About dot impact printer configuration)
A dot impact printer to which the recording head according to the present embodiment is applied will be described with reference to FIGS. FIG. 1 is a perspective view showing a printer main body of a dot impact printer, and FIG. 2 is a side sectional view of the printer main body of the dot impact printer. 1 and 2 indicates the width direction of the recording paper to be printed, that is, the moving direction of the carriage, and the Y direction indicates the protruding direction of the recording wire of the recording head mounted on the carriage. The Z direction indicates a direction orthogonal to the X direction and the Y direction.

  The dot impact printer is used in fields such as physical distribution and commercial distribution, and is mounted on a recording head while the recording head is mounted on a carriage that travels along the platen and the recording head travels in the axial direction of the platen. A plurality of recording wires are struck onto a recording sheet located on the front peripheral surface of the platen via an ink ribbon. In this way, information such as characters and images is recorded on the recording paper. The recording paper includes a passbook, an envelope, and the like in addition to a single-cut paper or continuous paper made of plain paper or copy paper.

As shown in FIGS. 1 and 2, the dot impact printer 100 includes at least a printer main body 50 having a frame unit 20, a printing mechanism unit 30, and a paper transport mechanism unit 40, a control device 80, and an unillustrated cover for these. And an exterior case.
The frame unit 20 includes at least a base frame 21 as a main body frame, a paper guide frame 22, a left side frame 23, and a right side frame 24. The printing mechanism unit 30 includes at least the recording head 18, a carriage 19 on which the recording head 18 is mounted, and a carriage moving mechanism unit 60 (see FIG. 5). The paper transport mechanism unit 40 includes a platen 41, a paper guide 42, a pinch roller 43, a push tractor unit 44, a discharge unit 45, and a paper supply guide 46.

  As shown in FIG. 1, the left side frame 23 and the right side frame 24 of the frame portion 20 are provided upright on both sides in the X direction in the figure, and between the left side frame 23 and the right side frame 24. A base frame 21 and a paper guide frame 22 (see FIG. 2) are arranged. In addition, a carriage guide shaft 32 and a platen 41 are rotatably spanned between the left side frame 23 and the right side frame 24. The paper guide 42 is disposed between the left side frame 23 and the right side frame 24 and is fitted and fixed to the paper guide frame 22. Furthermore, a tractor unit mounting portion and a discharge unit mounting portion (not shown) to which the push tractor unit 44 and the discharge unit 45 can be mounted are provided at the Y direction rear portions of the left side frame 23 and the right side frame 24.

  The push tractor unit 44 sends out continuous paper as the recording paper S to the paper transport mechanism unit 40. The paper supply guide 46 (see FIG. 2) supplies the cut paper as the recording paper S one by one (or one by one) to the paper transport mechanism unit 40. The discharge unit 45 discharges the recording paper S such as continuous paper or cut paper from the paper transport mechanism 40 to the outside of the dot impact printer 100. As shown in FIG. 2, the continuous paper is guided to the paper guide 42 of the paper transport mechanism 40 by the action of the pin 47 of the tractor belt 37 by the rotation of the tractor belt 37 of the push tractor unit 44. The continuous paper is fed forward in the Y direction of the platen 41 through a paper conveyance path 48 formed between the paper guide 42 and the platen 41, and is fed in the direction of arrow α in the figure.

  When the push tractor unit 44 is not in operation, it is possible to supply a single sheet of paper (or one by one) from the paper supply guide 46 to the front of the platen 41 via the paper transport path 48. Further, as will be described later, the continuous paper or the cut sheet on which characters and the like are recorded by the recording head 18 is rotated from the platen 41 of the paper transport mechanism unit 40 in the direction of arrow β in the drawing by the rotation of the discharge roller 49 of the discharge unit 45. Pulled out. As a result, the continuous paper or cut paper is conveyed in the Y direction (sub-scanning direction) orthogonal to the X direction (main scanning direction) of the carriage 19.

  The carriage 19 shown in FIG. 1 is slidably inserted into the carriage guide shaft 32 and has the recording head 18 mounted thereon. Since the carriage guide shaft 32 is arranged in parallel with the platen 41, the carriage 19 can move (run) in the X direction that coincides with the axial directions of the platen 41 and the carriage guide shaft 32. The carriage 19 is guided to the carriage guide shaft 32 via a timing belt 35 (see FIG. 2) by forward or reverse rotation of a carriage drive motor (not shown) and travels leftward or rightward in FIG. 1 along the X direction. .

  The recording head 18 includes a plurality of recording wires 9 (see FIG. 3), and an ink ribbon 36 (see FIG. 2) is positioned in front of the recording wires 9 in the protruding direction (Y direction). The recording head 18 causes the recording wire 9 to project while traveling in the X direction together with the carriage 19. Then, the recording wire 9 is struck against the ink ribbon 36, and the ink impregnated in the ink ribbon 36 adheres to the recording paper S (continuous paper or cut sheet paper) conveyed between the platen 41 and the ink ribbon 36. Thus, dots are formed on the recording paper S.

  While the carriage 19 travels leftward or rightward in the X direction, recording for one line is performed by the plurality of recording wires 9 of the recording head 18. When the recording sheet S is a continuous sheet each time one line of recording is performed, the platen 41, the push tractor unit 44, and the discharge unit 45 of the paper transport mechanism 40 shown in FIG. Transport a fixed amount (usually between lines). When the recording paper S is a cut sheet, the platen 41, the pinch roller 43, and the discharge unit 45 of the paper transport mechanism unit 40 transport the recording paper S by a predetermined amount (normal space). The recording operation by the recording head 18 is performed by repeating these operations.

  The dot impact printer 100 is formed with an opening between the base frame 21 and the paper guide frame 22, and is a bottom for supplying the recording paper S into the paper transport mechanism 40 from below in the Z direction in FIG. A paper supply port 39 is also provided.

  Note that the drive control of the paper transport mechanism unit 40, the carriage movement mechanism unit 60, and the printing mechanism unit 30 that perform the above operations is performed by the control of the control device 80. The control device 80 is mounted on a substrate or the like, and is disposed, for example, below the paper guide frame 22 in the Z direction behind the printer main body 50 in the Y direction. Details of the control device 80 will be described later.

(About the recording head)
Here, the recording head will be described with reference to FIGS. FIG. 3 is a cross-sectional view of the recording head, and FIG. 4 is an exploded perspective view of the recording head. The X direction, Y direction, and Z direction shown in FIGS. 3 and 4 are the same as the X direction, Y direction, and Z direction shown in FIGS.

  As shown in FIGS. 3 and 4, the recording head 18 is called a serial dot head, and includes a plurality of recording wires 9, a plurality of head coils (electromagnetic coils) 10, and a head that accommodates these. It has a main body 52, a nose part 53, a radiator 54, and a temperature detector (thermistor) 14. The recording head 18 is configured such that a nose portion 53 is connected to the head main body 52 in the Y direction in FIG. The recording wire 9 is formed by a wire pin having a circular cross-sectional view, and one dot is formed on the end surface of one recording wire 9. Therefore, a plurality of pins such as 9 pins, 16 pins, and 24 pins are provided according to the dot configuration (dot density) recorded by the recording head 18. In general, one head coil 10 is arranged corresponding to one recording wire 9.

  As shown in FIG. 3, the head main body 52 includes a frame 56, a wire lever 57, and a return spring 59 so as to accommodate the plurality of recording wires 9 and the head coil 10. The frame 56 is formed in a circular outer periphery, and a plurality of cores 55 around which the head coil 10 is wound are arranged at predetermined intervals in the circumferential direction. The recording lever 9 is connected to one end of the wire lever 57, and the wire lever 57 is attracted to the core 55 and driven by the energization operation to the head coil 10. The return spring 59 urges the wire lever 57 in a direction away from the core 55 with the pin 58 as a fulcrum. With such a configuration, when the wire lever 57 is attracted to the core 55, the recording wire 9 projects from the nose portion 53 in the Y direction (outward direction). The head main body 52 is stacked in two stages in the Y direction, which is the advancing / retreating direction of the recording wire 9, and arranged as a head main body combined body. However, in FIG. 3, only one head body 52 is shown.

  The nose portion 53 guides the advance / retreat operation including the protrusion operation of the recording wire 9, and includes a plurality of intermediate guides 62 arranged inside and one tip guide 63 arranged at the tip portion. The plurality of recording wires 9 are guided through the intermediate guide 62 and the tip guide 63 to advance and retreat. The plurality of recording wires 9 are arranged in a row or staggered manner along the Z direction on the tip guide 63 of the nose portion 53. FIG. 3 shows a case where one recording wire 9 passes through the intermediate guide 62 and the tip guide 63, and the other recording wires 9 are omitted.

  As shown in FIGS. 3 and 4, the radiator 54 is formed in a substantially cylindrical shape with a material having good thermal conductivity such as aluminum, and a plurality of fins 64 are integrally provided on the outside. The heat radiator 54 is disposed on the outer periphery of each head body 52 in the head body combined body described above and covers each head body 52. The head coil 10 of the head main body 52 generates heat as a heating element by printing operation, that is, energized. The heat radiator 54 has a function of cooling the head main body 52 by dissipating heat of the head main body 52 due to heat generated by the head coil 10 using the fins 64.

  As shown in FIG. 4, a temperature detector (thermistor) 14 for detecting the temperature of the frame 56 of the head body 52 is installed on the outer periphery of the frame 56 of one head body 52 of the head body combination. The temperature detector 14 is accommodated in a groove 66 formed on the inner peripheral surface 65 of the heat radiator 54 in a state where the heat radiator 54 is installed on the head main body 52 of the head main body combined body. The temperature detector 14 detects the temperature of the frame 56 of the head main body 52 and outputs it to the control device 80. Since the recording head 18 has the above-described structure, the temperature of the head coil 10 itself is higher than the temperature of the frame 56. For this reason, the temperature of the head coil 10 and the temperature of the frame 56 are correlated in advance to control the temperature of the head coil 10, in other words, the amount of heat generation.

(About control of dot impact printer)
Next, a control system of the dot impact printer will be described with reference to FIG. FIG. 5 is a block diagram illustrating a main configuration of the dot impact printer. As shown in FIG. 5, the dot impact printer 100 includes a printing mechanism unit 30 having a recording head 18, a carriage moving mechanism unit 60 having a carriage motor (not shown), a paper transport mechanism unit 40, and a temperature detector (thermistor) 14. A printer main body 50 having a detection unit 68 including a control unit 80 and a control device 80 that performs overall control thereof.

  The control device 80 includes a control unit 33 that is a main part of the control system, a head driver 82 that drives and controls the recording head 18, a motor driver 84 that drives the paper transport mechanism unit 40 and the carriage movement mechanism unit 60, and an interface unit. 85. The control unit 33 includes a CPU (Central Processing Unit) 86, an information processing unit 87, and a storage unit 88. The CPU 86 executes various processes such as an input signal process from an operation system and a detection system (not shown) and a printing process. The information processing unit 87 processes various information.

  The storage unit 88 includes a RAM (Random Access Memory), a ROM (Read Only Memory), and the like (not shown). The RAM temporarily stores various data such as print data input from the host computer 89 via the interface unit 85, and temporarily develops a program such as print processing executed by the CPU 86. Here, the print data indicates a pattern to be printed on the recording paper S by the recording head 18.

  The head driver 82 controls the recording wires 9 of the recording head 18 individually or in groups based on a command from the CPU 86. A method for controlling the recording head 18 will be described later. The motor driver 84 individually controls the motors of the paper transport mechanism unit 40 and the carriage movement mechanism unit 60 based on commands from the CPU 86. The interface unit 85 outputs the print data received from the host computer 89 to the control unit 33 and outputs various information received from the control unit 33 to the host computer 89.

(Recording head control method)
Here, a control method of the recording head will be described with reference to FIGS. FIG. 6 is a layout diagram of pattern detection areas in each dot line. FIG. 7 is an explanatory diagram of a special bit image as an example of a specific dot pattern used for determining the drive mode, and FIG. 7A is a first dot in which 50 dots are continuously formed by the same recording wire. FIG. 7B shows a second dot pattern in which 25 dots are formed every other dot in a length of 50 dots continuous by the same recording wire. FIG. 8 is a control table for determining the drive mode.

  The control unit 33 shown in FIG. 5 outputs a control signal to each head coil 10 of the recording head 18 via the head driver 82 based on print data, a control command, etc., and controls the energization state of each head coil 10. . A detection signal of the temperature detector 14 provided in the frame 56 of the recording head 18 shown in FIGS. 3 and 4 is input to the control unit 33. When performing printing, the control unit 33 determines whether the recording head 18 has exceeded a preset reference temperature based on the detection signal of the temperature detector 14. Based on the determination result, the drive mode of the recording head 18 at the time of printing, that is, the setting related to the energization control of the head coil 10 for driving each recording wire 9 is determined. The storage unit 88 of the control unit 33 stores data used for determination of such drive modes and control in each drive mode.

  As shown in FIG. 6, in this embodiment, one dot line is composed of, for example, a maximum of 136 digits (one digit is a width for one character), and within the maximum digit area of this one dot line, Five pattern detection areas 15 are set. That is, the pattern detection areas 15 are provided at the left and right ends of 136 digits, respectively, and the pattern detection areas 15 are arranged so that the remaining three pattern detection areas 15 are evenly arranged in the middle. When the width of each pattern detection area is 8 digits, the width of the non-detection area 16 between the adjacent pattern detection areas 15 is 24 digits. Note that one dot wire shown in FIG. 6 is handled by one recording wire 9 of the recording head 18.

  As shown in FIGS. 7A and 7B, the first dot pattern P1 as the special bit image is formed with, for example, 50 dots continuously by the same recording wire 9, and the second dot pattern P2 is the same. For example, 25 dots are formed every other dot in a length corresponding to 50 dots by the recording wire 9. The control unit 33 includes the first dot pattern P1 or the second dot pattern P2 in advance in the five pattern detection regions 15 in the dot line to be printed before printing each dot line. To determine whether or not Then, the number of pattern detection areas 15 (specific areas) including the first dot pattern P1 or the second dot pattern P2 in the dot line to be printed is counted, and this count number is set in advance. Whether the reference number N is equal to or greater than the reference number N or less. Based on the determination result, the drive mode of the recording head 18 when printing this dot line is determined. In this embodiment, any one of 2, 3, 4, and 5 can be set as the reference number N.

  Next, the control table for determining the drive mode shown in FIG. 8 will be described. In this embodiment, as a parameter for determining the drive mode of the recording head 18, in addition to the number of specific areas described above, a print quality setting designated for print data including a dot line to be printed is used. ing. The print quality is specified by a combination of two parameters, the print mode and the character quality. As the print mode, either “normal” or “copy” mode is designated. As the character quality, either “DRAFT” or “LQ (Letter Quality)” is designated. The DRAFT mode is specified for print data having a resolution lower than a preset reference resolution, and the LQ mode is specified for print data having a resolution equal to or higher than the reference resolution.

  As described above, in this embodiment, it is determined whether or not the recording head 18 has exceeded a preset reference temperature based on the detection signal of the temperature detector 14, and printing of each dot line is performed based on the determination result. The energization content to each head coil 10 at the time is adjusted. As this reference temperature, for example, three kinds of reference temperatures are used. In the control table of FIG. 8, the column displaying “special bit image” indicates that the number of specific areas is the number of specific areas when the number of specific areas is equal to or greater than the reference number N. Is less than the reference number N. The control table shows the number of specific areas when the number of specific areas is a reference number N or more (special bit image) for each of the four types of print quality including the combination of the above two types of print modes and character quality. In the case of less than the reference number N (except for the special bit image), three types of reference temperature set values are preset for these eight patterns.

  In the control table, the output value of the temperature detector 14 corresponding to each reference temperature, that is, the output value of the thermistor, for example, is displayed together with the set reference temperature. As shown in FIG. 8, the set values of the three types of reference temperatures are set values (second temperature) when the number of specific regions is equal to or greater than the reference number N, and when the number of specific regions is less than the reference number N. There are two types of set values (first temperature).

  The lowest reference temperature among the three reference temperatures is an interval printing condition for setting an interval time (head coil drive interval / non-printing time) from the end of energization for 1 dot formation to the start of the next energization. Yes, the output value of the temperature detector 14 corresponding to this reference temperature is Rin. The control unit 33 determines whether to use the initial interval (Tin1) or the high temperature interval (Tin2) by comparing and determining the output value of the temperature detector 14 and Rin. In this embodiment, the temperature settings of Tin1 and Tin2 are made different depending on the print quality setting, and the values of Tin1 and Tin2 corresponding to each print quality are as shown in the control table of FIG. Each is different.

  The next lowest reference temperature is bidirectional printing in which dot formation is performed in both the forward path and the backward path in the reciprocating movement of the carriage 19 in the X direction shown in FIG. 1, and unidirectional printing in which dot formation is performed only in either the forward path or the backward path. Uni-D printing conditions for setting which of the two is performed, and the output value of the temperature detector 14 corresponding to this reference temperature is Rhh. The control unit 33 determines whether to perform bidirectional printing or unidirectional printing based on a comparison determination between the output value of the temperature detector 14 and Rhh.

  The highest reference temperature is a print stop condition used for determining whether or not to stop printing, and the output value of the temperature detector 14 corresponding to this reference temperature is Rst.

(About the printing process flow)
Next, the flow of dot line printing processing will be described with reference to FIG. FIG. 9 is a flowchart showing the flow of printing processing of each dot line using the control table. In step S <b> 1 shown in FIG. 9, the control unit 33 detects the output value R of the temperature detector 14 and performs a comparison determination with an output value corresponding to a preset reference temperature. The reference temperature used here is a value lower than the interval printing condition, which is the lowest temperature among the above-described three types of reference temperatures. For example, the reference temperature is 17 ° C. (the output value of the corresponding temperature detector 14 is 71. 51KΩ). If the temperature of the recording head 18 is equal to or lower than the reference temperature, that is, if R ≧ 71.51 KΩ (step S1: Yes), it is determined that the temperature of the recording head 18 is sufficiently low and the process proceeds to step S2.

In step S2, the drive mode under the above conditions is set. The control unit 33 sets the head coil drive frequency f to 1.44 KHz, for example, and sets the head coil energization time Pw to Pwn + 10 μs in the normal mode and Pwc in the copy mode. Here, the head coil drive frequency f is the frequency of the pulse voltage applied to the head coil 10 of the recording head 18 and means the maximum number of protrusion operations per unit time in the recording wire 9. Pwn is a preset normal energization time in the normal mode, and Pwc is a preset energization time in the copy mode. For the head coil drive interval, for example, an initial interval (Tin1) corresponding to the print quality can be selected from the values in the column “other than special bit image”. Alternatively, other interval values may be set separately. Then, the process proceeds to step S3.
In step S3, printing of the dot line to be printed is executed in the drive mode having the contents set in step S2. Then, the process ends.

In step S1 shown in FIG. 9, when the temperature T of the recording head 18 is higher than the reference temperature (step S1: No), the process proceeds to step S4.
In step S4, a special bit image detection determination is performed. A special bit image (first dot pattern P1 or second dot pattern P2) detection process in the five pattern detection areas 15 shown in FIG. 6 and a comparison determination between the number of detection points and the reference number N are performed. If the number of pattern detection areas 15 (specific areas) in which the special bit image has been detected is N or more (step S4: Yes), the process proceeds to step S5.

In step S5, the control unit 33 refers to the control table of FIG. 8, and uses the temperatures in the “special bit image” column for the print quality specified for the current print data as the three types of reference temperatures. select. Then, output values Rin, Rhh, Rst corresponding to the selected reference temperature are set as determination values for determining the drive mode.
On the other hand, when the number of pattern detection areas 15 in which the special bit image is detected is less than N in step S4 (step S4: No), the process proceeds to step S6.
In step S6, referring to the control table of FIG. 8, the temperature in the column “other than special bit image” in the print quality specified for the current print data is selected as the three types of reference temperatures. Then, the output values Rin, Rhh, Rst of the temperature detector 14 corresponding to the selected reference temperature are set as determination values for determining the drive mode.

  When the process proceeds to step S5 in the determination in step S4 shown in FIG. 9, in subsequent steps S7 to S12, the output value R of the temperature detector 14 is compared with Rin, Rhh, Rst, and the result is determined. To set the drive mode. In step S5, the three types of reference temperatures (second temperatures) in this case are 65 ° C., 75 ° C., and 107 ° C., respectively.

  First, in step S7, a comparison is made with the output value Rin corresponding to the interval printing condition (65 ° C.), which is the lowest reference temperature. Here, if R> Rin (the temperature T <65 ° C. of the recording head 18) (step S7: No), the process proceeds to step S8, and the values of the head coil drive frequency f and the head coil energization time Pw are set as follows. Set to the value associated with the current print quality. Further, the head coil driving interval at this time is set to Tin1. Then, the process proceeds to step S3, the printing of the dot line to be printed is executed in the drive mode having the contents set in step S8, and the process ends.

  On the other hand, if R ≦ Rin (temperature T ≧ 65 ° C. of the recording head 18) in step S7 (step S7: Yes), the process proceeds to step S9 and corresponds to the Uni-D printing condition (75 ° C.). Comparison with the output value Rhh to be performed is performed. If R> Rhh (the temperature T <75 ° C. of the recording head 18) (step S9: No), the process proceeds to step S10, and the values of the head coil drive frequency f and the head coil energization time Pw are obtained this time. Is set to a value associated with the print quality. Further, the head coil driving interval at this time is set to Tin2. Then, the process proceeds to step S3, the printing of the dot line to be printed is executed in the drive mode having the contents set in step S10, and the process ends.

  Next, when R ≦ Rhh (temperature T ≧ 75 ° C. of the recording head 18) in step S9 (step S9: Yes), the process proceeds to step S11 to correspond to the print stop condition (107 ° C.). Comparison with the output value Rst is performed. If R> Rst (the temperature T <107 ° C. of the recording head 18) (step S11: No), the process proceeds to step S12, and the values of the head coil drive frequency f and the head coil energization time Pw are obtained this time. Is set to a value associated with the print quality. Further, the head coil driving interval at this time is set to Tin2. Then, the process proceeds to step S3, the printing of the dot line to be printed is executed in the drive mode having the contents set in step S12, and the process ends. On the other hand, if R ≦ Rst (107 ° C.) in step S11 (step S11: Yes), the process proceeds to step S13, and during a preset delay time (time for radiating the recording head 18). Stop printing. Then, it returns to step S1 and restarts processing.

  When the process proceeds to step S6 in the determination of step S4 shown in FIG. 9, in subsequent steps S14 to S19, the temperature R of the recording head 18 is compared with the reference temperatures Rin, Rhh, Rst, and the results are determined. To set the drive mode. In step S6, the reference temperatures Rin, Rhh, and Rst (first temperatures) in this case are 102 ° C., 107 ° C., and 110 ° C., respectively. Steps S14 to S19 are performed in the same manner as steps S7 to S12 except that the three types of reference temperatures are set higher than when the processes of steps S7 to S12 are performed.

  Here, the drive mode setting contents in steps S8, S10, and S12 are the same as the setting contents in steps S15, S17, and S19, respectively. That is, in this embodiment, as shown in FIGS. 8 and 9, when the reference temperature of the recording head 18 for changing the drive mode to each setting content of steps S8, S10, and S12 is “special bit image”. Is lower than in the case of “non-special bit image”, and in the case of “special bit image”, even if the temperature of the recording head 18 is the same, the drive mode with less heat generation is set. .

The effects of this example will be described below.
As described above, in this embodiment, when the pattern detection area 15 and the special bit image in the dot line to be printed are collated, and the number of pattern detection areas 15 including the special bit image is equal to or more than the reference number N, The reference value of the temperature of the recording head 18 for switching to the driving mode in which the heat generation amount is small and the printing speed is slow is set to a low temperature (second temperature). On the other hand, when the number is less than the reference number N, the reference value of the temperature of the recording head 18 for switching to the drive mode in which the heat generation amount is small and the printing speed is slow is set to a temperature (first temperature) higher than the second temperature. ing. For this reason, the drive mode of the recording head 18 is used until the number of pattern detection areas 15 including a special bit image is 1 or less and the temperature of the recording head 18 is assumed not to exceed the burnout limit temperature of the head coil 10. However, there is no need to switch to a drive mode in which the amount of heat generation is small and the printing speed is slow. Therefore, it is possible to suppress a decrease in print throughput more than necessary while preventing the head coil 10 from being burned out.

  As mentioned above, although the Example of this invention was described, various deformation | transformation can be added with respect to the said Example in the range which does not deviate from the meaning of this invention. For example, modifications other than the above embodiment are as follows.

(First modification)
In the above embodiment, as the special bit image, the first dot pattern P1 in which 50 dots are continuously formed by the same recording wire 9 and every other dot in the length of 50 dots continuous by the same recording wire 9 are used. Although two types of the second dot pattern P2 for forming 25 dots are shown, other dot patterns can be used as the special bit image. For example, when the special bit image is a continuous dot, the number of continuous dots formed (that is, the number of times the corresponding head coil 10 is continuously driven) is set to the width of each pattern detection region 15, the interval between adjacent pattern detection regions 15, dots It can be set according to the maximum line length (maximum digit) of the line. Further, a dot pattern in which dots of a predetermined ratio or more out of the number of dots corresponding to the width of each pattern detection area 15 can be used as a special bit image. Alternatively, a special bit image in which a predetermined number or more of the plurality of recording wires 9 mounted on the recording head 18 simultaneously form the first dot pattern P1 or the second dot pattern P2 can be used.

(Second modification)
In the above embodiment, a plurality of pattern detection areas 15 are set in the dot line range and the special bit image is detected only in the pattern detection area 15. However, the pattern detection area 15 is not set and one dot line is detected. It is also possible to determine how many special bit images are detected in the entire range of the maximum digit, and to determine the drive mode based on the number of detected locations. Alternatively, the number of pattern detection areas 15 can be increased, and the width of the non-detection areas between the adjacent pattern detection areas 15 can be made shorter.

(Third Modification)
In the above embodiment, the processing is not different depending on the content of the detected special bit image (whether the first dot pattern P1 or the second dot pattern P2 is detected). Accordingly, the drive mode may be set differently. In addition, the interval between the plurality of pattern detection areas 15 including the special bit image, the dot density in the area near the special bit image, or the print contents (print history) performed before printing the dot line to be printed are You may use as a parameter for setting a drive mode.

  DESCRIPTION OF SYMBOLS 9 ... Recording wire, 10 ... Head coil, 14 ... Temperature detector, 15 ... Pattern detection area | region, 16 ... Non-detection area | region, 18 ... Recording head, 30 ... Printing mechanism part, 33 ... Control part, 40 ... Paper conveyance mechanism part 48 ... paper transport path, 50 ... printer main body, 52 ... head main body, 53 ... nose, 54 ... radiator, 60 ... carriage moving mechanism, 68 ... detection unit, 80 ... control device, 82 ... head driver, 88 ... Storage unit, 100 ... Dot impact printer.

Claims (7)

A method for controlling a recording head in a dot impact printer that prints information on a recording medium by driving the recording wire while scanning a carriage on which a recording head having a plurality of recording wires is mounted,
Each recording wire is in charge of printing one dot line in the scanning direction of the carriage,
In printing the dot line,
Before execution of printing, it is determined whether or not a specific dot pattern set in advance is included in the dot line to be printed more than a reference number of 2 or more,
A recording head control method, comprising: determining a driving mode of the recording head for printing the dot line based on the determination result. In the area of the maximum line length of the dot line, a plurality of pattern detection areas of a predetermined width are set in advance,
In printing the dot line,
Before performing printing, it is determined whether the pattern detection area in the dot line to be printed is a specific area including the specific dot pattern,
Determining whether the number of the specific areas in the dot line is equal to or greater than the reference number;
2. The recording head control method according to claim 1, wherein a driving mode of the recording head for printing the dot lines is determined based on the determination results. As the drive mode of the recording head, a plurality of the drive modes with different calorific values are set in advance, and each drive mode and the temperature of the print head are associated with each other,
The temperature of the recording head associated with each of the drive modes includes at least two temperatures of a first temperature and a second temperature lower than the first temperature,
In printing the dot line,
Detect the temperature of the recording head before printing,
When the number of the specific areas in the dot line to be printed is equal to or more than the reference number, the driving mode corresponding to the detected temperature of the recording head is selected using the second temperature,
When the number of the specific areas in the dot line to be printed is less than the reference number, the drive mode corresponding to the detected temperature of the recording head is selected using the first temperature,
3. The recording head control method according to claim 1, wherein printing of the dot lines is executed according to the selected driving mode. When the temperature of the recording head detected before printing is below a preset reference temperature,
4. The recording head according to claim 1, wherein the driving mode of the recording head is determined without using a determination result of whether or not the pattern detection area is the specific area. 5. Control method. Associating the print quality of the print data with the drive mode of the recording head,
In printing the dot line,
The dot line is printed in the drive mode determined from the drive modes associated with the print quality of the print data including the dot line to be printed. 5. A method for controlling a recording head according to any one of 4 above.   6. The specific dot pattern is set based on the number of the recording wires that are simultaneously driven during printing and the number of continuous drivings of the same recording wire. The recording head control method according to one item. A carriage that is scanned in a direction substantially perpendicular to the feeding direction of the recording medium on which information is printed;
A recording head mounted on the carriage and having a plurality of recording wires forming a print dot row in a dot line;
A control unit for controlling the recording head,
7. The dot according to claim 1, wherein the control unit determines a driving mode of the recording head and executes printing of the dot line by the recording head control method according to claim 1. Impact printer.

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